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Title: Micrographia

Author: Robert Hooke

Release date: March 29, 2005 [eBook #15491]
Most recently updated: May 24, 2021

Language: English

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*** START OF THE PROJECT GUTENBERG EBOOK
MICROGRAPHIA ***

By the Council of the ROYAL SOCIETY of
London
for Improving of Natural Knowledge.
Ordered, That the Book written by Robert Hooke, M.A. Fellow of this
Society, Entituled, Micrographia, or some Physiological Descriptions of
Minute Bodies, made by Magnifying Glasses, with Observations and
Inquiries thereupon, Be printed by John Martyn, and James Allestry,
Printers to the said Society.
Novem. 23. 1664.
BROUNCKER. P.R.S.

MICROGRAPHIA:
OR SOME

Physiological Descriptions

OF

MINUTE BODIES
MADE BY

MAGNIFYING GLASSES

WITH

OBSERVATIONS and INQUIRIES thereupon.

By R. HOOKE, Fellow of the ROYAL SOCIETY.

Non possis oculo quantum contendere
Linceus,
Non tamen idcirco contemnas Lippus inungi.
Horat. Ep. lib. 1.

LONDON, Printed by Jo. Martyn, and Ja. Allestry, Printers to the
ROYAL SOCIETY, and are to be sold at their Shop at the Bell in S. Paul’s
Church-yard. M DC LX V.

TO THE

KING.

SIR,

Do here most humbly lay this small Present at Your
Majesties Royal feet. And though it comes accompany’d with two
disadvantages, the meanness of the Author, and of the Subject; yet in both I
am incouraged by the greatness of your Mercy and your Knowledge. By the
one I am taught, that you can forgive the most presumptuous Offendors:
And by the other, that you will not esteem the least work of Nature, or Art,
unworthy your Observation. Amidst the many felicities that have
accompani’d your Majesties happy Restauration and Government, it is none
of the least considerable that Philosophy and Experimental Learning have
prosper’d under your Royal Patronage. And as the calm prosperity of your
Reign has given us the leisure to follow these Studies of quiet and
retirement, so it is just, that the Fruits of them should, by way of
acknowledgement, be return’d to your Majesty. There are, Sir, several other
of your Subjects, of your Royal Society, now busie about Nobler matters:
The Improvement of Manufactures and Agriculture, the Increase of
Commerce, the Advantage of Navigation: In all which they are assisted by
your Majesties Incouragement and Example. Amidst all those greater
Designs, I here presume to bring in that which is more proportionable to the
smalness of my Abilities, and to offer some of the least of all visible things,
to that Mighty King, that has establisht an Empire over the best of all
Invisible things of this World, the Minds of Men.
Your Majesties most humble
and most obedient
Subject and Servant,

ROBERT HOOKE.

TO THE

ROYAL SOCIETY.

fter my Address to our Great Founder and Patron, I
could not but think my self oblig’d, in consideration of those many
Ingagements you have laid upon me, to offer these my poor Labours to this
MOST ILLUSTRIOUS ASSEMBLY. YOU have been pleas’d formerly to
accept of these rude Draughts. I have since added to them some
Descriptions, and some Conjectures of my own. And therefore, together
with YOUR Acceptance, I must also beg YOUR pardon. The Rules YOU
have prescrib’d YOUR selves in YOUR Philosophical Progress do seem the
best that have ever yet been practis’d. And particularly that of avoiding
Dogmatizing, and the espousal of any Hypothesis not sufficiently grounded
and confirm’d by Experiments. This way seems the most excellent, and may
preserve both Philosophy and Natural History from its former Corruptions.
In saying which, I may seem to condemn my own Course in this Treatise; in
which there may perhaps be some Expressions, which may seem more
positive then YOUR Prescriptions will permit: And though I desire to have
them understood only as Conjectures and Quæries (which YOUR Method
does not altogether disallow) yet if even in those I have exceeded, ’tis fit
that I should declare, that it was not done by YOUR Directions. For it is
most unreasonable, that YOU should undergo the imputation of the faults of
my Conjectures, seeing YOU can receive so small advantage of reputation
by the sleight Observations of
YOUR most humble and
most faithful Servant

ROBERT HOOKE.

THE
PREFACE.

t is the great prerogative of Mankind above other
Creatures, that we are not only able to behold the works of Nature, or
barely to sustein our lives by them, but we have also the power of
considering, comparing, altering, assisting, and improving them to various
uses. And as this is the peculiar priviledge of humane Nature in general, so
is it capable of being so far advanced by the helps of Art, and Experience,
as to make some Men excel others in their Observations, and Deductions,
almost as much as they do Beasts. By the addition of such artificial
Instruments and methods, there may be, in some manner, a reparation made
for the mischiefs, and imperfection, mankind has drawn upon it self, by
negligence, and intemperance, and a wilful and superstitious deserting the
Prescripts and Rules of Nature, whereby every man, both from a deriv’d
corruption, innate and born with him, and from his breeding and converse
with men, is very subject to slip into all sorts of errors.
The only way which now remains for us to recover some degree of those
former perfections, seems to be, by rectifying the operations of the Sense,
the Memory, and Reason, since upon the evidence, the strength, the
integrity, and the right correspondence of all these, all the light, by which
our actions are to be guided is to be renewed, and all our command over
things is to be establisht.
It is therefore most worthy of our consideration, to recollect their several
defects, that so we may the better understand how to supply them, and by
what assistances we may inlarge their power, and secure them in performing
their particular duties.

As for the actions of our Senses, we cannot but observe them to be in
many particulars much outdone by those of other Creatures, and when at
best, to be far short of the perfection they seem capable of: And these
infirmities of the Senses arise from a double cause, either from the
disproportion of the Object to the Organ, whereby an infinite number of
things can never enter into them, or else from error in the Perception, that
many things, which come within their reach, are not received in a right
manner.
The like frailties are to be found in the Memory; we often let many things
slip away from us, which deserve to be retain’d, and of those which we
treasure up, a great part is either frivolous or false; and if good, and
substantial, either in tract of time obliterated, or at best so overwhelmed
and buried under more frothy notions, that when there is need of them, they
are in vain sought for.
The two main foundations being so deceivable, it is no wonder, that all
the succeeding works which we build upon them, of arguing, concluding,
defining, judging, and all the other degrees of Reason, are lyable to the
same imperfection, being, at best, either vain, or uncertain: So that the
errors of the understanding are answerable to the two other, being defective
both in the quantity and goodness of its knowledge; for the limits, to which
our thoughts are confin’d, are small in respect of the vast extent of Nature it
self; some parts of it are too large to be comprehended, and some too little
to be perceived. And from thence it must follow, that not having a full
sensation of the Object, we must be very lame and imperfect in our
conceptions about it, and in all the proportions which we build upon it;
hence, we often take the shadow of things for the substance, small
appearances for good similitudes, similitudes for definitions; and even
many of those, which we think, to be the most solid definitions, are rather
expressions of our own misguided apprehensions then of the true nature of
the things themselves.
The effects of these imperfections are manifested in different ways,
according to the temper and disposition of the several minds of men, some
they incline to gross ignorance and stupidity, and others to a presumptuous
imposing on other mens Opinions, and a confident dogmatizing on matters,
whereof there is no assurance to be given.

Thus all the uncertainty, and mistakes of humane actions, proceed either
from the narrowness and wandring of our Senses, from the slipperiness or
delusion of our Memory, from the confinement or rashness of our
Understanding, so that ’tis no wonder, that our power over natural causes
and effects is so slowly improv’d, seeing we are not only to contend with the
obscurity and difficulty of the things whereon we work and think, but even
the forces of our own minds conspire to betray us.
These being the dangers in the process of humane Reason, the remedies
of them all can only proceed from the real, the mechanical, the experimental
Philosophy, which has this advantage over the Philosophy of discourse and
disputation, that whereas that chiefly aims at the subtilty of its Deductions
and Conclusions, without much regard to the first ground-work, which
ought to be well laid on the Sense and Memory; so this intends the right
ordering of them all, and the making them serviceable to each other.
The first thing to be undertaken in this weighty work, is a watchfulness
over the failings and an inlargement of the dominion, of the Senses.
To which end it is requisite, first, That there should be a scrupulous
choice, and a strict examination, of the reality, constancy, and certainty of
the Particulars that we admit: This is the first rise whereon truth is to
begin, and here the most severe, and most impartial diligence, must be
imployed; the storing up of all, without any regard to evidence or use, will
only tend to darkness and confusion. We must not therefore esteem the
riches of our Philosophical treasure by the number only, but chiefly by the
weight; the most vulgar Instances are not to be neglected, but above all, the
most instructive are to be entertain’d; the footsteps of Nature are to be
trac’d, not only in her ordinary course, but when she seems to be put to her
shifts, to make many doublings and turnings, and to use some kind of art in
indeavouring to avoid our discovery.
The next care to be taken, in respect of the Senses, is a supplying of their
infirmities with Instruments, and, as it were, the adding of artificial Organs
to the natural; this in one of them has been of late years accomplisht with
prodigious benefit to all sorts of useful knowledge, by the invention of
Optical Glasses. By the means of Telescopes, there is nothing so far distant
but may be represented to our view; and by the help of Microscopes, there

is nothing so small, as to escape our inquiry; hence there is a new visible
World discovered to the understanding. By this means the Heavens are
open’d, and a vast number of new Stars, and new Motions, and new
Productions appear in them, to which all the antient Astronomers were
utterly Strangers. By this the Earth it self, which lyes so neer us, under our
feet, shews quite a new thing to us, and in every little particle of its matter;
we now behold almost as great a variety of Creatures, as we were able
before to reckon up in the whole Universe it self.
It seems not improbable, but that by these helps the subtilty of the
composition of Bodies, the structure of their parts, the various texture of
their matter, the instruments and manner of their inward motions, and all
the other possible appearances of things, may come to be more fully
discovered; all which the antient Peripateticks were content to comprehend
in two general and (unless further explain’d) useless words of Matter and
Form. From whence there may arise many admirable advantages, towards
the increase of the Operative, and the Mechanick Knowledge, to which this
Age seems so much inclined, because we may perhaps be inabled to discern
all the secret workings of Nature, almost in the same manner as we do those
that are the productions of Art, and are manag’d by Wheels, and Engines,
and Springs, that were devised by humane Wit.
In this kind I here present to the World my imperfect Indeavours; which
though they shall prove no other way considerable, yet, I hope, they may be
in some measure useful to the main Design of a reformation in Philosophy,
if it be only by shewing, that there it not so much requir’d towards it, any
strength of Imagination, or exactness of Method, or depth of Contemplation
(though the addition of these, where they can be had, must needs produce a
much more perfect composure) as a sincere Hand, and a faithful Eye, to
examine, and to record, the things themselves as they appear.
And I beg my Reader, to let me take the boldness to assure him, that in
this present condition of knowledge, a man so qualified, as I have
indeavoured to be, only with resolution, and integrity, and plain intentions
of imploying his Senses aright, may venture to compare the reality and the
usefulness of his services, towards the true Philosophy, with those of other
men, that are of much stronger, and more acute speculations, that shall not
make use of the same method by the Senses.

The truth is, the Science of Nature has been already too long made only a
work of the Brain and the Fancy: It is now high time that it should return to
the plainness and soundness of Observations on material and obvious
things. It is said of great Empires, That the best way to preserve them from
decay, is to bring them back to the first Principles, and Arts, on which they
did begin. The same is undoubtedly true in Philosophy, that by wandring far
away into invisible Notions, has almost quite destroy’d it self, and it can
never be recovered, or continued, but by returning into the same sensible
paths, in which it did at first proceed.
If therefore the Reader expects from me any infallible Deductions, or
certainty of Axioms, I am to say for my self, that those stronger Works of
Wit and Imagination are above my weak Abilities; or if they had not been
so, I would not have made use of them in this present Subject before me:
Whenever he finds that I have ventur’d at any small Conjectures, at the
causes of the things that I have observed, I beseech him to look upon them
only as doubtful Problems, and uncertain ghesses, and not as
unquestionable Conclusions, or matters of unconfutable Science; I have
produced nothing here, with intent to bind his understanding to an implicit
consent; I am so far from that, that I desire him, not absolutely to rely upon
these Observations of my eyes, if he finds them contradicted by the future
Ocular Experiments of sober and impartial Discoverers.
As for my part, I have obtained my end, if these my small Labours shall
be thought fit to take up some place in the large stock of natural
Observations, which so many hands are busie in providing. If I have
contributed the meanest foundations whereon others may raise nobler
Superstructures, I am abundantly satisfied; and all my ambition is, that I
may serve to the great Philosophers of this Age, as the makers and the
grinders of my Glasses did to me; that I may prepare and furnish them with
some Materials, which they may afterwards order and manage with better
skill, and to far greater advantage.
The next remedies in this universal cure of the Mind are to be applied to
the Memory, and they are to consist of such Directions as may inform us,
what things are best to be stor’d up for our purpose, and which is the best
way of so disposing them, that they may not only be kept in safety, but
ready and convenient, to be at any time produc’d for use, as occasion shall

require. But I will not here prevent my self in what I may say in another
Discourse, wherein I shall make an attempt to propose some Considerations
of the manner of compiling a Natural and Artificial History, and of so
ranging and registring its Particulars into Philosophical Tables, as may
make them most useful for the raising of Axioms and Theories.
The last indeed is the most hazardous Enterprize, and yet the most
necessary; and that is, to take such care that the Judgment and the Reason
of Man (which is the third Faculty to be repair’d and improv’d) should
receive such assistance, as to avoid the dangers to which it is by nature
most subject. The Imperfections, which I have already mention’d, to which
it is lyable, do either belong to the extent, or the goodness of its knowledge;
and here the difficulty is the greater, least that which may be thought a
remedy for the one should prove destructive to the other, least by seeking to
inlarge our Knowledge, we should render it weak and uncertain; and least
by being too scrupulous and exact about every Circumstance of it, we
should confine and streighten it too much.
In both these the middle wayes are to be taken, nothing is to be omitted,
and yet every thing to pass a mature deliberation: No Intelligence from Men
of all Professions, and quarters of the World, to be slighted, and yet all to
be so severely examin’d, that there remain no room for doubt or instability;
much rigour in admitting, much strictness in comparing, and above all,
much slowness in debating, and shyness in determining, is to be practised.
The Understanding is to order all the inferiour services of the lower
Faculties; but yet it is to do this only as a lawful Master, and not as a
Tyrant. It must not incroach upon their Offices, nor take upon it self the
employments which belong to either of them. It must watch the
irregularities of the Senses, but it must not go before them, or prevent their
information. It must examine, range, and dispose of the bank which is laid
up in the Memory: but it must be sure to make distinction between the sober
and well collected heap, and the extravagant Ideas, and mistaken Images,
which there it may sometimes light upon. So many are the links, upon which
the true Philosophy depends, of which, if any one be loose, or weak, the
whole chain is in danger of being dissolv’d; it is to begin with the Hands
and Eyes, and to proceed on through the Memory, to be continued by the
Reason; nor is it to stop there, but to come about to the Hands and Eyes
again, and so, by a continual passage round from one Faculty to another, it

is to be maintained in life and strength, as much as the body of man is by
the circulation of the blood through the several parts of the body, the Arms,
the Feet, the Lungs, the Heart, and the Head.
If once this method were followed with diligence and attention, there is
nothing that lyes within the power of human Wit (or which is far more
effectual) of human Industry, which we might not compass; we might not
only hope for Inventions to equalize those of Copernicus, Galileo, Gilbert,
Harvy, and of others, whose Names are almost lost, that were the Inventors
of Gun-powder, the Seamans Compass, Printing, Etching, Graving,
Microscopes, &c. but multitudes that may far exceed them: for even those
discoveries seem to have been the products of some such method, though
but imperfect; What may not be therefore expected from it if thoroughly
prosecuted? Talking and contention of Arguments would soon be turn’d
into labours; all the fine dreams of Opinions, and universal metaphysical
natures, which the luxury of subtil Brains has devis’d, would quickly vanish,
and give place to solid Histories, Experiments and Works. And as at first,
mankind fell by tasting of the forbidden Tree of Knowledge, so we, their
Posterity, may be in part restor’d by the same way, not only by beholding
and contemplating, but by tasting too those fruits of Natural knowledge,
that were never yet forbidden.
From hence the World may be assisted with variety of Inventions, new
matter for Sciences may be collected, the old improv’d, and their rust
rubb’d away; and as it is by the benefit of Senses that we receive all our
Skill in the works of Nature, so they also may be wonderfully benefited by it,
and may be guided to an easier and more exact performance of their
Offices; ’tis not unlikely, but that we may find out wherein our Senses are
deficient, and as easily find wayes of repairing them.
The Indeavours of Skilful men have been most conversant about the
assistance of the Eye, and many noble Productions have followed upon it;
and from hence we may conclude, that there is a way open’d for advancing
the operations, not only of all the other Senses, but even of the Eye it self;
that which has been already done ought not to content us, but rather to
incourage us to proceed further, and to attempt greater things in the same
and different wayes.

’Tis not unlikely, but that there may be yet invented several other helps
for the eye, at much exceeding those already found, as those do the bare
eye, such as by which we may perhaps be able to discover living Creatures
in the Moon, or other Planets, the figures of the compounding Particles of
matter, and the particular Schematisms and Textures of Bodies.
And as Glasses have highly promoted our seeing, so ’tis not improbable,
but that there may be found many Mechanical Inventions to improve our
other Senses, of hearing, smelling, tasting, touching. ’Tis not impossible to
hear a whisper a furlongs distance, it having been already done; and
perhaps the nature of the thing would not make it more impossible, though
that furlong should be ten times multiply’d. And though some famous
Authors have affirm’d it impossible to hear through the thinnest plate of
Muscovy-glass; yet I know a way, by which ’tis easie enough to hear one
speak through a wall a yard thick. It has not been yet thoroughly examin’d,
how far Otocousticons may be improv’d, nor what other wayes there may
be of quickning our hearing, or conveying sound through other bodies then
the Air: for that that is not the only medium, I can assure the Reader, that I
have, by the help of a distended wire, propagated the sound to a very
considerable distance in an instant, or with as seemingly quick a motion as
that of light, at least, incomparably swifter then that, which at the same
time was propagated through the Air; and this not only in a straight line, or
direct, but in one bended in many angles.
Nor are the other three so perfect, but that diligence, attention, and many
mechanical contrivances, may also highly improve them. For since the
sense of smelling seems to be made by the swift passage of the Air
(impregnated with the steams and effluvia of several odorous Bodies)
through the grisly meanders of the Nose whose surfaces are cover’d with a
very sensible nerve, and moistned by a transudation from the processus
mamillares of the Brain, and some adjoyning glandules, and by the moist
steam of the Lungs, with a Liquor convenient for the reception of those
effluvia and by the adhesion and mixing of those steams with that liquor,
and thereby affecting the nerve, or perhaps by insinuating themselves into
the juices of the brain, after the same manner, as I have in the following
Observations intimated, the parts of Salt to pass through the skins of Effs,
and Frogs. Since, I say, smelling seems to be made by some such way, ’tis
not improbable, but that some contrivance, for making a great quantity of

Air pass quick through the Nose, might as much promote the sense of
smelling, as the any wayes hindring that passage does dull and destroy it.
Several tryals I have made, both of hindring and promoting this sense, and
have succeeded in some according to expectation; and indeed to me it
seems capable of being improv’d, for the judging of the constitutions of
many Bodies. Perhaps we may thereby also judge (as other Creatures seem
to do) what is wholsome, what poyson; and in a word, what are the
specifick properties of Bodies.
There may be also some other mechanical wayes found out, of sensibly
perceiving the effluvia of Bodies; several Instances of which, were it here
proper, I could give of Mineral steams and exhalations; and it seems not
impossible, but that by some such wayes improved, may be discovered, what
Minerals lye buried under the Earth, without the trouble to dig for them;
some things to confirm this Conjecture may be found in Agricola, and other
Writers of Minerals, speaking of the Vegetables that are apt to thrive, or
pine, in those steams.
Whether also those steams, which seem to issue out of the Earth, and mix
with the Air (and so to precipitate some aqueous Exhalations, wherewith ’tis
impregnated) may not be by some way detected before they produce the
effect, seems hard to determine; yet something of this kind I am able to
discover, by an Instrument I contriv’d to shew all the minute variations in
the pressure of the Air; by which I constantly find, that before, and during
the time of rainy weather, the pressure of the Air is less, and in dry weather,
but especially when an Eastern Wind (which having past over vast tracts of
Land is heavy with Earthy Particles) blows, it is much more, though these
changes are varied according to very odd Laws.

The Instrument is this. I prepare a pretty capacious Bolt-head
AB, with a small stem about two foot and a half long DC; upon
the end of this D I put on a small bended Glass, or brazen syphon
DEF (open at D, E and F, but to be closed with cement at F and E,
as occasion serves) whose stem F should be about six or eight
inches long, but the bore of it not above half an inch diameter, and
very even; these I fix very strongly together by the help of very
hard Cement, and then fit the whole Glass ABCDEF into a long
Board, or Frame, in such manner, that almost half the head AB

may lye buried in a concave Hemisphere cut into the Board RS;
Schem. 1.
Fig. 1. then I place it so on the Board RS, as is exprest in the first
figure of the first Scheme; and fix it very firm and steady in that
posture, so as that the weight of the Mercury that is afterwards to
be put into it, may not in the least shake or stir it; then drawing a
line XY on the Frame RT, so that it may divide the ball into two
equal parts, or that it may pass, as ’twere, through the center of
the ball. I begin from that, and divide all the rest of the Board
towards UT into inches, and the inches between the 25 and the
end E (which need not be above two or three and thirty inches
distant from the line XY) I subdivide into Decimals; then
stopping the end F with soft Cement, or soft Wax, I invert the
Frame, placing the head downwards, and the Orifice E upwards;
and by it, with a small Funnel, I fill the whole Glass with
Quicksilver; then by stopping the small Orifice E with my finger,
I oftentimes erect and invert the whole Glass and Frame, and
thereby free the Quicksilver and Glass from all the bubbles or
parcels of lurking Air; then inverting it as before, I fill it top full
with clear and well strain’d Quicksilver, and having made ready a
small ball of pretty hard Cement, by heat made very soft, I press it
into the hole E, and thereby stop it very fast; and to secure this
Cement from flying out afterward, I bind over it a piece of
Leather, that is spread over in the inside with Cement, and wound
about it while the Cement is hot: Having thus fastned it, I gently
erect again the Glass after this manner: I first let the Frame down
edge-wayes, till the edge RV touch the Floor, or ly horizontal; and
then in that edging posture raise the end RS; this I do, that if there
chance to be any Air hidden in the small Pipe E, it may ascend
into the Pipe F, and not into the Pipe DC: Having thus erected it,
and hung it by the hole Q, or fixt it perpendicularly by any other
means, I open the end F, and by a small Syphon I draw out the
Mercury so long, till I find the surface of it AB in the head to
touch exactly the line XY; at which time I immediately take away
the Syphon, and if by chance it be run somewhat below the line
XY, by pouring in gently a little Mercury at F, I raise it again to its
desired height, by this contrivance I make all the sensible rising

and falling of the Mercury to be visible in the surface of the
Mercury in the Pipe F, and scarce any in the head AB. But
because there really is some small change of the upper surface
also, I find by several Observations how much it rises in the Ball,
and falls in the Pipe F, to make the distance between the two
surfaces an inch greater then it was before; and the measure that it
falls in the Pipe is the length of the inch by which I am to mark
the parts of the Tube F, or the Board on which it lyes, into inches
and Decimals: Having thus justned and divided it, I have a large
Wheel MNOP, whose outmost limb is divided into two hundred
equal parts; this by certain small Pillars is fixt on the Frame RT, in
the manner exprest in the Figure. In the middle of this, on the
back side, in a convenient frame, is placed a small Cylinder,
whose circumference is equal to twice the length of one of those
divisions, which I find answer to an inch of ascent, or descent, of
Mercury: This Cylinder I, is movable on a very small Needle, on
the end of which is fixt a very light Index KL, all which are so
pois’d on the Axis, or Needle, that no part is heavier then another:
Then about this Cylinder is wound a small Clew of Silk, with two
small steel Bullets at each end of it GH; one of these, which is
somewhat the heavier, ought to be so big, as freely to move to and
fro in the Pipe F; by means of which contrivance, every the least
variation of the height of the Mercury will be made exceeding
visible by the motion to and fro of the small Index KL.

But this is but one way of discovering the effluvia of the Earth mixt with
the Air; there may be perhaps many others, witness the Hygroscope, an
Instrument whereby the watery steams volatile in the Air are discerned,
which the Nose it self is not able to find. This I have describ’d in the
following Tract in the Description of the Beard of a wild Oat. Others there
are, may be discovered both by the Nose, and by other wayes also. Thus the
smoak of burning Wood is smelt, seen, and sufficiently felt by the eyes: The
fumes of burning Brimstone are smelt and discovered also by the
destroying the Colours of Bodies, as by the whitening of a red Rose: And
who knows, but that the Industry of man, following this method, may find
out wayes of improving this sense to as great a degree of perfection at it is
in any Animal, and perhaps yet higher.

’Tis not improbable also, but that our taste may be very much improv’d,
either by preparing our taste for the Body, as, after eating bitter things,
Wine, or other Vinous liquors, are more sensibly tasted; or else by
preparing Bodies for our tast; as the dissolving of Metals with acid Liquors,
make them tastable, which were before altogether insipid; thus Lead
becomes sweeter then Sugar, and Silver more bitter then Gall, Copper and
Iron of most loathsome tasts. And indeed the business of this sense being to
discover the presence of dissolved Bodies in Liquors put on the Tongue, or
in general to discover that a fluid body has some solid body dissolv’d in it,
and what they are; whatever contrivance makes this discovery improves this
sense. In this kind the mixtures of Chymical Liquors afford many Instances;
as the sweet Vinegar that is impregnated with Lead may be discovered to be
so by the affusion of a little of an Alcalizate solution: The bitter liquor of
Aqua fortis and Silver may be discover’d to be charg’d with that Metal, by
laying in it some plates of Copper: ’Tis not improbable also, but there may
be multitudes of other wayes of discovering the parts dissolv’d, or
dissoluble in liquors; and what is this discovery but a kind of secundary
tasting.
’Tis not improbable also, but that the sense of feeling may be highly
improv’d, for that being a sense that judges of the more gross and robust
motions of the Particles of Bodies, seems capable of being improv’d and
assisted very many wayes. Thus for the distinguishing of Heat and Cold, the
Weather-glass and Thermometer, which I have describ’d in this following
Treatise, do exceedingly perfect it; by each of which the least variations of
heat or cold, which the most Acute sense is not able to distinguish, are
manifested. This is oftentimes further promoted also by the help of Burning-
glasses, and the like, which collect and unite the radiating heat. Thus the
roughness and smoothness of a Body is made much more sensible by the
help of a Microscope, then by the most tender and delicate Hand. Perhaps,
a Physitian might, by several other tangible proprieties, discover the
constitution of a Body as well as by the Pulse. I do but instance in these, to
shew what possibility there may be of many others, and what probability
and hopes there were of finding them, if this method were followed; for the
Offices of the five Senses being to detect either the subtil and curious
Motions propagated through all pellucid or perfectly homogeneous Bodies;
Or the more gross and vibrative Pulse communicated through the Air and

all other convenient mediums, whether fluid or solid: Or the effluvia of
Bodies dissolv’d in the Air; Or the particles of bodies dissolv’d or
dissoluble in Liquors, or the more quick and violent shaking motion of heat
in all or any of these: whatsoever does any wayes promote any of these
kinds of criteria, does afford a way of improving some one sense. And what
a multitude of these would a diligent Man meet with in his inquiries? And
this for the helping and promoting the sensitive faculty only.
Next, as for the Memory, or retentive faculty, we may be sufficiently
instructed from the written Histories of civil actions, what great assistance
may be afforded the Memory, in the committing to writing things observable
in natural operations. If a Physitian be therefore accounted the more able in
his Faculty, because he has had long experience and practice, the
remembrance of which, though perhaps very imperfect, does regulate all his
after actions: What ought to be thought of that man, that has not only a
perfect register of his own experience, but is grown old with the experience
of many hundreds of years, and many thousands of men.
And though of late, men, beginning to be sensible of this convenience,
have here and there registred and printed some few Centuries, yet for the
most part they are set down very lamely and imperfectly, and, I fear, many
times not so truly, they seeming, several of them, to be design’d more for
Ostentation then publique use: For, not to instance, that they do, for the
most part, omit those Experiences they have made, wherein their Patients
have miscarried, it is very easie to be perceiv’d, that they do all along
hyperbolically extol their own Prescriptions, and vilifie those of others.
Notwithstanding all which, these kinds of Histories are generally esteem’d
useful, even to the ablest Physitian.
What may not be expected from the rational or deductive Faculty that is
furnisht with such Materials, and those so readily adapted, and rang’d for
use, that in a moment, as ’twere, thousands of Instances, serving for the
illustration, determination, or invention, of almost any inquiry, may be
represented even to the sight? How neer the nature of Axioms must all
those Propositions be which are examin’d before so many Witnesses? And
how difficult will it be for any, though never so subtil an error in
Philosophy, to scape from being discover’d, after it has indur’d the touch,
and so many other tryals?

What kind of mechanical way, and physical invention also is there
requir’d that might not this way be found out? The Invention of a way to
find the Longitude of places is easily perform’d, and that to as great
perfection as is desir’d, or to at great an accurateness as the Latitude of
places can be found at Sea; and perhaps yet also to a greater certainty then
that has been hitherto found, as I shall very speedily freely manifest to the
world. The way of flying in the Air seems principally unpracticable, by
reason of the want of strength in humane muscles; if therefore that could be
suppli’d, it were, I think, easie to make twenty contrivances to perform the
office of Wings: What Attempts also I have made for the supplying that
Defect, and my successes therein, which, I think, are wholly new, and not
inconsiderable, I shall in another place relate.
’Tis not unlikely also, but that Chymists, if they followed this method,
might find out their so much sought for Alkahest. What an universal
Menstruum, which dissolves all sorts of Sulphureous Bodies, I have
discover’d (which has not been before taken notice of as such) I have shewn
in the sixteenth Observation.
What a prodigious variety of Inventions in Anatomy has this latter Age
afforded, even in our own Bodies in the very Heart, by which we live, and
the Brain, which is the seat of our knowledge of other things? witness all
the excellent Works of Pecquet, Bartholinus, Billius, and many others; and
at home, of Doctor Harvy, Doctor Ent, Doctor Willis, Doctor Glisson. In
Celestial Observations we have far exceeded all the Antients, even the
Chaldeans and Egyptians themselves, whose vast Plains, high Towers, and
clear Air, did not give them so great advantages over us, as have over them
by our Glasses. By the help of which, they have been very much outdone by
the famous Galileo, Hevelius, Zulichem; and our own Countrymen, Mr.
Rook, Doctor Wren, and the great Ornament of our Church and Nation, the
Lord Bishop of Exeter. And to say no more in Aerial Discoveries, there has
been a wonderful progress made by the Noble Engine of the most Illustrious
Mr. Boyle, whom it becomes me to mention with all honour, not only as my
particular Patron, but as the Patron of Philosophy it self; which he every
day increases by his Labours, and adorns by his Example.
The good success of all these great Men, and many others, and the now
seemingly great obviousness of most of their and divers other Inventions,

which from the beginning of the world have been, as ’twere, trod on, and yet
not minded till these last inquisitive Ages (an Argument that there may be
yet behind multitudes of the like) puts me in mind to recommend such
Studies, and the prosecution of them by such methods, to the Gentlemen of
our Nation, whose leisure makes them fit to undertake, and the plenty of
their fortunes to accomplish, extraordinary things in this way. And I do not
only propose this kind of Experimental Philosophy as a matter of high
rapture and delight of the mind, but even as a material and sensible
Pleasure. So vast it the variety of Objects which will come under their
Inspections, so many different wayes there are of handling them, so great is
the satisfaction of finding out new things, that I dare compare the
contentment which they will injoy, not only to that of contemplation, but
even to that which most men prefer of the very Senses themselves.
And if they will please to take any incouragement from so mean and so
imperfect endeavours as mine, upon my own experience, I can assure them,
without arrogance, That there has not been any inquiry or Problem in
Mechanicks, that I have hitherto propounded to my self, but by a certain
method (which I may on some other opportunity explain) I have been able
presently to examine the possibility of it; and if so, as easily to excogitate
divers wayes of performing it: And indeed it is possible to do as much by
this method in Mechanicks, as by Algebra can be perform’d in Geometry.
Nor can I at all doubt, but that the same method is as applicable to Physical
Enquiries, and as likely to find and reap thence as plentiful a crop of
Inventions; and indeed there seems to be no subject so barren, but may with
this good husbandry be highly improv’d.
Toward the prosecution of this method in Physical Inquiries, I have here
and there gleaned up an handful of Observations, in the collection of most
of which I made use of Microscopes, and some other Glasses and
Instruments that improve the sense; which way I have herein taken, not that
there are not multitudes of useful and pleasant Observables, yet
uncollected, obvious enough without the helps of Art, but only to promote
the use of Mechanical helps for the Senses, both in the surveying the
already visible World, and for the discovery of many others hitherto
unknown, and to make us, with the great Conqueror, to be affected that we
have not yet overcome one World when there are so many others to be

discovered, every considerable improvement of Telescopes or Microscopes
producing new Worlds and Terra-Incognita’s to our view.
The Glasses I used were of our English make, but though very good of
the kind, yet far short of what might be expected, could we once find a way
of making Glasses Elliptical, or of some more true shape; for though both
Microscopes, and Telescopes, as they now are, will magnifie an Object
about a thousand thousand times bigger then it appears to the naked eye;
yet the Apertures of the Object-glasses are so very small, that very few Rays
are admitted, and even of those few there are so many false, that the Object
appears dark and indistinct: And indeed these inconveniences are such, as
seem inseparable from Spherical Glasses, even when most exactly made;
but the way we have hitherto made use of for that purpose is so imperfect,
that there may be perhaps ten wrought before one be made tolerably good,
and most of those ten perhaps every one differing in goodness one from
another, which is an Argument, that the way hitherto used is, at least, very
uncertain. So that these Glasses have a double defect; the one, that very few
of them are exactly true wrought; the other, that even of those that are best
among them, none will admit a sufficient number of Rayes to magnifie the
Object beyond a determinate bigness. Against which Inconveniences the
only Remedies I have hitherto met with are these.

First, for Microscopes (where the Object we view is near and
within our power) the best way of making it appear bright in the
Glass, is to cast a great quantity of light on it by means of convex
glasses, for thereby, though the aperture be very small, yet there
will throng in through it such multitudes, that an Object will by
this means indure to be magnifi’d as much again as it would be
without it. The way for doing which is this. I make choice of
some Room that has only one window open to the South, and at
about three or four foot distance from this Window, on a Table, I
place my Microscope, and then so place either a round Globe of
Water, or a very deep clear plano convex Glass (whose convex
side is turn’d towards the Window) that there is a great quantity
of Rayes collected and thrown upon the Object: Or if the Sun
shine, I place a small piece of oyly Paper very near the Object,
between that and the light; then with a good large Burning-Glass I
so collect and throw the Rayes on the Paper, that there may be a

very great quantity of light pass through it to the Object; yet I so
proportion that light, that it may not singe or burn the Paper.
Instead of which Paper there may be made use of a small piece of
Looking-glass plate, one of whose sides is made rough by being
rubb’d on a flat Tool with very fine sand, this will, if the heat be
leisurely cast on it, indure a much greater degree of heat, and
consequently very much augment a convenient light. By all which
means the light of the Sun, or of a Window, may be so cast on an
Object, as to make it twice as light as it would otherwise be
without it, and that without any inconvenience of glaring, which
the immediate light of the Sun is very apt to create in most
Objects; for by this means the light is so equally diffused, that all
parts are alike inlightned; but when the immediate light of the Sun
falls on it, the reflexions from some few parts are so vivid, that
they drown the appearance of all the other, and are themselves
also, by reason of the inequality of light, indistinct, and appear
only radiant spots.
But because the light of the Sun, and also that of a Window, is
in a continual variation, and so many Objects cannot be view’d
long enough by them to be throughly examin’d; besides that,
oftentimes the Weather is so dark and cloudy, that for many dayes
together nothing can be view’d: And because also there are many
Objects to be met with in the night, which cannot so conveniently
be kept perhaps till the day, therefore to procure and cast a
sufficient quantity of light on an Object in the night, I thought of,
and often used this, Expedient.
Schem. 1.
Fig. 5.

I procur’d me a small Pedestal, such as is describ’d in the fifth
Figure of the first Scheme on the small Pillar AB, of which were
two movable Armes CD, which by means of the Screws EF, I
could fix in any part of the Pillar; on the undermost of these I
plac’d a pretty large Globe of Glass G, fill’d with exceeding clear
Brine, stopt, inverted, and fixt in the manner visible in the Figure;
out of the side of which Arm proceeded another Arm H, with
many joynts; to the end of which was fastned a deep plain Convex

glass I, which by means of this Arm could be moved to and fro,
and fixt in any posture. On the upper Arm was placed a small
Lamp K, which could be so mov’d upon the end of the Arm, as to
be set in a fit posture to give light through the Ball: By means of
this Instrument duly plac’d, as is exprest in the Figure, with the
small flame of a Lamp may be cast as great and convenient a light
on the Object as it will well indure; and being always constant,
and to be had at any time, I found most proper for drawing the
representations of those small Objects I had occasion to observe.
None of all which ways (though much beyond any other
hitherto made use of by any I know) do afford a sufficient help,
but after a certain degree of magnifying, they leave us again in the
lurch. Hence it were very desirable, that some way were thought
of for making the Object-glass of such a Figure as would
conveniently bear a large Aperture.

As for Telescopes, the only improvement they seem capable of, is the
increasing of their length; for the Object being remote, there is no thought
of giving it a greater light then it has; and therefore to augment the
Aperture, the Glass must be ground of a very large sphere; for, by that
means, the longer the Glass be, the bigger aperture will it bear, if the
Glasses be of an equal goodness in their kind. Therefore a six will indure a
much larger Aperture then a three foot Glass, and a sixty foot Glass will
proportionably bear a greater Aperture then a thirty, and will as much excel
it also as a six foot does a three foot, as I have experimentally observ’d in
one of that length made by Mr. Richard Reives here at London, which will
bear an Aperture above three inches over, and yet make the Object
proportionably big and distinct; whereas there are very few thirty foot
Glasses that will indure an Aperture of more then two inches over. So that
for Telescopes, supposing we had a very ready way of making their Object
Glasses of exactly spherical Surfaces, we might, by increasing the length of
the Glass, magnifie the Object to any assignable bigness. And for
performing both these, I cannot imagine any way more easie, and more
exact, then by this following Engine, by means of which, any Glasses, of
what length soever, may be speedily made. It seems the most easie, because
with one and the same Tool may be with care ground an Object Glass, of
any length or breadth requisite, and that with very little or no trouble in

fitting the Engine, and without much skill in the Grinder. It seems to be the
most exact, for to the very last stroke the Glass does regulate and rectifie
the Tool to its exact Figure; and the longer or more the Tool and Glass are
wrought together, the more exact will both of them be of the desir’d Figure.
Further, the motions of the Glass and Tool do so cross each other, that there
is not one point of eithers Surface, but has thousands of cross motions
thwarting it, so that there can be no kind of Rings or Gutters made either in
the Tool or Glass.

The contrivance of the Engine is, only to make the ends of two
large Mandrils so to move, that the Centers of them may be at any
convenient distance asunder, and that the Axis of the Mandrils
lying both in the same plain produc’d, may meet each other in any
assignable Angle; both which requisites may be very well Schem. 1.
Fig. 3. perform’d by the Engine describ’d in the third Figure of the
first Scheme: where AB signifies the Beam of a Lath fixt
perpendicularly or Horizontally, CD the two Poppet heads, fixt at
about two foot distance, EF an Iron Mandril, whose tapering neck
F runs in an adapted tapering brass Collar; the other end E runs on
the point of a Screw G; in a convenient place of this is fastned H a
pully Wheel, and into the end of it, that comes through the Poppet
head C, is screwed a Ring of a hollow Cylinder K, or some other
conveniently shap’d Tool, of what wideness shall be thought most
proper for the cize of Glasses, about which it is to be imploy’d:
As, for Object glasses, between twelve foot and an hundred foot
long, the Ring may be about six inches over, or indeed somewhat
more for those longer Glasses. It would be convenient also, and
not very chargeable, to have four or five several Tools; as one for
all Glasses between an inch and a foot, one for all Glasses
between a foot and ten foot long, another for all between ten and
an hundred, a fourth for all between a hundred and a thousand
foot long; and if Curiosity shall ever proceed so far, one for all
lengths between a thousand and ten thousand foot long; for
indeed the principle is such, that supposing the Mandrils well
made, and of a good length, and supposing great care be used in
working and polishing them, I see no reason, but that a Glass of a
thousand, nay of ten thousand foot long, may be as well made as

one of ten; for the reason is the same, supposing the Mandrils and
Tools be made sufficiently strong, so that they cannot bend; and
supposing the Glass, out of which they are wrought, be capable of
so great a regularity in its parts as to refraction: this hollow
Cylinder K is to contain the Sand, and by being drove round very
quick to and fro by means of a small Wheel, which may be mov’d
with ones foot, serves to grind the Glass: The other Mandril is
shap’d like this, but it has an even neck instead of a taper one, and
runs in a Collar, that by the help of a Screw and a joynt made like
M in the Figure, it can be still adjustned to the wearing or wasting
neck: into the end of this Mandril is screwed a Chock N on which
with Cement or Glew is fastned the piece of Glass Q that is to be
form’d; the middle of which Glass is to be plac’d just on the edge
of the Ring, and the Lath OP is to be set and fixt (by means of
certain pieces and screws, the manner whereof will be sufficiently
evidenc’d by the Figure) in such an Angle as is requisite to the
forming of such a Sphere as the Glass is design’d to be of; the
geometrical ground of which being sufficiently plain, though not
heeded before, I shall, for brevities sake, pass over. This last
Mandril to be made (by means of the former, or some other
Wheel) to run round very swift also, by which two cross motions
the Glass cannot chuse (if care be us’d) but be wrought into a
most exactly spherical Surface.

But because we are certain, from the Laws of refraction (which I I have
experimentally found to be so, by an Instrument I shall presently describe)
that the lines of the angles of Incidence are proportionate to the lines of the
angles of Refraction, therefore if Glasses could be made of those kind of
Figures, or some other, such as the most incomparable Des Cartes has
invented, and demonstrated in his Philosophical and Mathematical Works,
we might hope for a much greater perfection of Opticks then can be
rationally expected from spherical ones; for though, cæteris paribus, we
find, that the larger the Telescope Object Glasses are, and the shorter those
of the Microscope, the better they magnifie, yet both of them, beside such
determinate dimensions, are by certain inconveniences rendred unuseful;
for it will be exceeding difficult to make and manage a Tube above an

hundred foot long, and it will be as difficult to inlighten an Object less then
an hundred part of an inch distant from the Object Glass.
I have not as yet made any attempts of that kind, though I know two or
three wayes, which, as far as I have yet considered, seem very probable,
and may invite me to make a tryal as soon as I have an opportunity, of
which I may hereafter perhaps acquaint the world. In the Interim, I shall
describe the Instrument I even now mention’d, by which the refraction of all
kinds of Liquors may be most exactly measur’d, thereby to give the curious
an opportunity of making what further tryals of that kind they shall think
requisite to any of their intended tryals; and to let them see that the laws of
Refraction are not only notional.
Schem. 1.
Fig. 2.

The Instrument consisted of five Rulers, or long pieces placed
together, after the manner exprest in the second Figure of the first
Scheme, where AB denotes a straight piece of wood about six foot
and two inches long, about three inches over, and an inch and half
thick, on the back side of which was hung a small plummet by a
line stretcht from top to bottom, by which this piece was set
exactly upright, and so very firmly fixt; in the middle of this was
made a hole or center, into which one end of a hollow cylindrical
brass Box CC, fashion’d as I shall by and by describe, was plac’d,
and could very easily and truly be mov’d to and fro; the other end
of this Box being put into, and moving in, a hole made in a small
arm DD; into this box was fastned the long Ruler EF, about three
foot and three or four inches long, and at three foot from the
above mention’d Centers PP was a hole E, cut through, and
cross’d with two small threads, and at the end of it was fixt a
small sight G, and on the back side of it was fixt a small Arm H,
with a Screw to fix it in any place on the Ruler LM; this Ruler
LM was mov’d on the Center B (which was exactly three foot
distance from the middle Center P) and a line drawn through the
middle of it LM, was divided by a Line of cords into some sixty
degrees, and each degree was subdivided into minutes, so that
putting the cross of the threads in E upon any part of this divided

line, I presently knew what Angle the two Rules AB and EF made
with each other, and by turning the Screw in H, I could fix them
in any position. The other Ruler also RS was made much after the
same manner, only it was not fixt to the hollow cylindrical Box,
but, by means of two small brass Armes or Ears, it mov’d on the
Centers of it; this also, by means of the cross threads in the hole
S, and by a Screw in K, could be fastned on any division of
another line of cords of the same radius drawn on NO. And so by
that means, the Angle made by the two Rulers, AB and RS, was
also known. The Brass box CC in the middle was shap’d very
much like the Figure X, that is, it was a cylindrical Box stopp’d
close at either end, off of which a part both of the sides and
bottomes was cut out, so that the Box, when the Pipe and that was
joyned to it, would contain the Water when fill’d half full, and
would likewise, without running over, indure to be inclin’d to an
Angle, equal to that of the greatest refraction of Water, and no
more, without running over. The Ruler EF was fixt very fast to the
Pipe V, so that the Pipe V directed the length of the Ruler EF, and
the Box and Ruler were mov’d on the Pin TT, so as to make any
desirable Angle with the Ruler AB. The bottom of this Pipe V was
stop’d with a small piece of exactly plain Glass, which was plac’d
exactly perpendicular to the Line of direction, or Axis of the Ruler
EF. The Pins also TT were drill’d with small holes through the
Axis, and through those holes was stretcht and fastned a small
Wire. There was likewise a small Pipe of Tin loosly put on upon
the end of V, and reaching down to the sight G; the use of which
was only to keep any false Rayes of light from passing through
the bottom of V, and only admitting such to pass as pierced
through the sight G: All things being placed together in the
manner describ’d in the Figure; that is, the Ruler AB being fixt
perpendicular, I fill’d the Box CC with Water, or any other
Liquor, whose refraction I intended to try, till the Wire passing
through the middle of it were just covered: then I moved and fixt
the Ruler FE at any assignable Angle, and placed the flame of a
Candle just against the sight G; and looking through the sight I, I
moved the Ruler RS to and fro, till I perceived the light passing
through G to be covered, as ’twere, or divided by the dark Wire

passing through PP: then turning the Screw in K, I fixt it in that
posture: And through the hole S, I observed what degree and part
of it was cut by the cross threads in S. And this gave me the Angle
of Inclination, APS answering to the Angle of Refraction BPE: for
the surface of the Liquor in the Box will be alwayes horizontal,
and consequently AB will be a perpendicular to it; the Angle
therefore APS will measure, or be the Angle of Inclination in the
Liquor; next EPB must be the Angle of Refraction, for the Ray
that passes through the sight G, passes also perpendicularly
through the Glass Diaphragme at F, and consequently also
perpendicularly through the lower surface of the Liquor
contiguous to the Glass, and therefore suffers no refraction till it
meet with the horizontal surface of the Liquor in CC, which is
determined by the two Angles.

By means of this Instrument I can with little trouble, and a very small
quantity of any Liquor, examine, most accurately, the refraction of it not
only for one inclination, but for all; and thereby am inabled to make very
accurate Tables; several of which I have also experimentally made, and
find, that Oyl of Turpentine has a much greater Refraction then Spirit of
Wine, though it be lighter; and that Spirit of Wine has a greater Refraction
then Water, though it be lighter also; but that salt Water also has a greater
Refraction then fresh, though it be heavier: but Alum water has a less
refraction then common Water, though heavier also. So that it seems, as to
the refraction made in a Liquor, the specifick gravity is of no efficacy. By
this I have also found that look what proportion the Sine of the Angle of one
Inclination has to the Sine of the Angle of Refraction, correspondent to it,
the same proportion have all the Sines of other Inclinations to the Sines of
their appropriate Refractions.

My way for measuring how much a Glass magnifies an Object,
plac’d at a convenient distance from my eye, is this. Having
rectifi’d the Microscope, to see the desir’d Object through it very
distinctly, at the same time that I look upon the Object through the
Glass with one eye, I look upon other Objects at the same
distance with my other bare eye; by which means I am able, by
the help of a Ruler divided into inches and small parts, and laid

on the Pedestal of the Microscope, to cast, as it were, the
magnifi’d appearance of the Object upon the Ruler, and thereby
exactly to measure the Diameter it appears of through the Glass,
which being compar’d with the Diameter it appears of to the
naked eye, will easily afford the quantity of its magnifying.
Schem. 1.
Fig. 3.

The Microscope, which for the most part I made use of, was
shap’d much like that in the sixth Figure of the first Scheme, the
Tube being for the most part not above six or seven inches long,
though, by reason it had four Drawers, it could very much be
lengthened, as occasion required; this was contriv’d with three
Glasses; a small Object Glass at A, a thinner Eye Glass about B,
and a very deep one about C: this I made use of only when I had
occasion to see much of an Object at once; the middle Glass
conveying a very great company of radiating Pencils, which
would go another way, and throwing them upon the deep Eye
Glass. But when ever I had occasion to examine the small parts of
a Body more accurately, I took out the middle Glass, and only
made use of one Eye Glass with the Object Glass, for always the
fewer the Refractions are, the more bright and clear the Object
appears. And therefore ’tis not to be doubted, but could we make
a Microscope to have one only refraction, it would, cæteris
paribus, far excel any other that had a greater number. And hence
it is, that if you take a very clear piece of a broken Venice Glass,
and in a Lamp draw it out into very small hairs or threads, then
holding the ends of these threads in the flame, till they melt and
run into a small round Globul, or drop, which will hang at the end
of the thread; and if further you stick several of these upon the
end of a stick with a little sealing Wax, so as that the threads stand
upwards, and then on a Whetstone first grind off a good part of
them, and afterward on a smooth Metal plate, with a little Tripoly,
rub them till they come to be very smooth; if one of these be fixt
with a little soft Wax against a small needle hole, prick’d through
a thin Plate of Brass, Lead, Pewter, or any other Metal, and an
Object, plac’d very near, be look’d at through it, it will both

magnifie and make some Objects more distinct then any of the
great Microscopes. But because these, though exceeding easily
made, are yet very troublesome to be us’d, because of their
smalness, and the nearness of the Object; therefore to prevent
both these, and yet have only two Refractions, I Schem. 1.
Fig. 4. provided me a Tube of Brass, shap’d much like that in the
fourth Figure of the first Scheme; into the smaller end of this I fixt
with Wax a good plano convex Object Glass, with the convex side
towards the Object, and into the bigger end I fixt also with wax a
pretty large plano Convex Glass, with the convex side towards my
eye, then by means of the small hole by the side, I fill’d the
intermediate space between these two Glasses with very clear
Water, and with a Screw stopp’d it in; then putting on a Cell for
the Eye, I could perceive an Object more bright then I could when
the intermediate space was only fill’d with Air, but this, for other
inconveniences, I made but little use of.
Schem. 1.
Fig. 3.

My way for fixing both the Glass and Object to the Pedestal
most conveniently was thus: Upon one side of a round Pedestal
AB, in the sixth Figure of the first Scheme, was fixt a small Pillar
CC, on this was fitted a small Iron Arm D, which could be mov’d
up and down, and fixt in any part of the Pillar, by means of a
small Screw E; on the end of this Arm was a small Ball fitted into
a kind of socket F, made in the side of the Brass Ring G, through
which the small end of the Tube was screw’d; by means of which
contrivance I could place and fix the Tube in what posture I
desir’d (which for many Observations was exceeding necessary)
and adjusten it most exactly to any Object.
For placing the Object, I made this contrivance; upon the end
of a small brass Link or Staple HH, I so fastned a round Plate II,
that it might be turn’d round upon its Center K, and going pretty
stiff, would stand fixt in any posture it was set; on the side of this
was fixt a small Pillar P, about three quarters of an inch high, and
through the top of this was thrust a small Iron pin M, whose top
just stood over the Center of the Plate; on this top I fixt a small

Object, and by means of these contrivances I was able to turn it
into all kind of positions, both to my Eye and the Light; for by
moving round the small Plate on its center, could move it one
way, and by turning the Pin M, I could move it another way, and
this without stirring the Glass at all, or at least but very little; the
Plate likewise I could move to and fro to any part of the Pedestal
(which in many cases was very convenient) and fix it also in any
Position, by means of a Nut N, which was screw’d on upon the
lower part of the Pillar CC. All the other Contrivances are
obvious enough from the draught, and will need no description.

Now though this were the Instrument I made most use of, yet I have made
several other Tryals with other kinds of Microscopes, which both for matter
and form were very different from common spherical Glasses. I have made
a Microscope with one piece of Glass, both whose surfaces were plains. I
have made another only with a plano concave, without any kind of
reflection, divers also by means of reflection. I have made others of Waters,
Gums, Resins, Salts, Arsenick, Oyls, and with divers other mixtures of
watery and oyly Liquors. And indeed the subject is capable of a great
variety; but I find generally none more useful then that which is made with
two Glasses, such as I have already describ’d.
What the things are I observ’d, the following descriptions will manifest;
in brief, they were either exceeding small Bodies, or exceeding small Pores,
or exceeding small Motions, some of each of which the Reader will find in
the following Notes, and such, as I presume, (many of them at least) will be
new, and perhaps not less strange: Some specimen of each of which Heads
the Reader will find in the subsequent delineations, and indeed of some
more then I was willing there should be; which was occasioned by my first
Intentions to print a much greater number then I have since found time to
compleat. Of such therefore as I had, I selected only some few of every
Head, which for some particulars seem’d most observable, rejecting the rest
as superfluous to the present Design.
What each of the delineated Subjects are, the following descriptions
annext to each will inform, of which I shall here, only once for all, add,
That in divers of them the Gravers have pretty well follow’d my directions
and draughts; and that in making of them, I indeavoured (as far as I was

able) first to discover the true appearance, and next to make a plain
representation of it. This I mention the rather, because of these kind of
Objects there is much more difficulty to discover the true shape, then of
those visible to the naked eye, the same Object seeming quite differing, in
one position to the Light, from what it really is, and may be discover’d in
another. And therefore I never began to make any draught before by many
examinations in several lights, and in several positions to those lights, I had
discover’d the true form. For it is exceeding difficult in some Objects, to
distinguish between a prominency and a depression, between a shadow and
a black stain, or a reflection and a whiteness in the colour. Besides, the
transparency of most Objects renders them yet much more difficult then if
they were opacous. The Eyes of a Fly in one kind of light appear almost like
a Lattice, drill’d through with abundance of small holes; which probably
may be the Reason, why the Ingenious Dr. Power seems to suppose them
such. In the Sunshine they look like a Surface cover’d with golden Nails; in
another posture, like a Surface cover’d with Pyramids; in another with
Cones; and in other postures of quite other shapes; but that which exhibits
the best, is the Light collected on the Object, by those means I have already
describ’d.
And this was undertaken in prosecution of the Design which the ROYAL
SOCIETY has propos’d to it self. For the Members of the Assembly having
before their eys so many fatal Instances of the errors and falshoods, in
which the greatest part of mankind has so long wandred, because they
rely’d upon the strength of humane Reason alone, have begun anew to
correct all Hypotheses by sense, as Seamen do their dead Reckonings by
Cœlestial Observations; and to this purpose it has been their principal
indeavour to enlarge & strengthen the Senses by Medicine, and by such
outward Instruments as are proper for their particular works. By this means
they find some reason to suspect, that those effects of Bodies, which have
been commonly attributed to Qualities, and those confess’d to be occult, are
perform’d by the small Machines of Nature, which are not to be discern’d
without these helps, seeming the meer products of Motion, Figure, and
Magnitude; and that the Natural Textures, which some call the Plastick
faculty, may be made in Looms, which a greater perfection of Opticks may
make discernable by these Glasses; so as now they are no more puzzled
about them, then the vulgar are to conceive, how Tapestry or flowred Stuffs

are woven. And the ends of all these Inquiries they intend to be the Pleasure
of Contemplative minds, but above all, the ease and dispatch of the labours
of mens hands. They do indeed neglect no opportunity to bring all the rare
things of Remote Countries within the compass of their knowledge and
practice. But they still acknowledg their most useful Informations to arise
from common things, and from diversifying their most ordinary operations
upon them. They do not wholly reject Experiments of meer light and theory;
but they principally aim at such, whose Applications will improve and
facilitate the present way of Manual Arts. And though some men, who are
perhaps taken up about less honourable Employments, are pleas’d to
censure their proceedings, yet they can shew more fruits of their first three
years, wherein they have assembled, then any other Society in Europe can
for a much larger space of time. ’Tis true, such undertakings as theirs do
commonly meet with small incouragement, because men are generally
rather taken with the plausible and discursive, then the real and the solid
part of Philosophy; yet by the good fortune of their institution, in an Age of
all others the most inquisitive, they have been assisted by the contribution
and presence of very many of the chief Nobility and Gentry, and others who
are some of the most considerable in their several Professions. But that that
yet farther convinces me of the Real esteem that the more serious part of
men have of this Society, is, that several Merchants, men who act in earnest
(whose Object is meum & tuum, that great Rudder of humane affairs) have
adventur’d considerable sums of Money, to put in practice what some of
our Members have contrived, and have continued stedfast in their good
opinions of such Indeavours, when not one of a hundred of the vulgar have
believed their undertakings feasable. And it is also fit to be added, that they
have one advantage peculiar to themselves, that very many of their number
are men of Converse and Traffick; which is a good Omen, that their
attempts will bring Philosophy from words to action, seeing the men of
Business have had so great a share in their first foundation.
And of this kind I ought not to conceal one particular Generosity, which
more nearly concerns my self. It is the munificence of Sir John Cutler, in
endowing a Lecture for the promotion of Mechanick Arts, to be governed
and directed by This Society.This Bounty I mention for the Honourableness
of the thing it self, and for the expectation which I have of the efficacy of
the Example; for it cannot now be objected to them, that their Designs will

be esteemed frivolous and vain, when they have such a real Testimony of
the Approbation of a Man that is such an eminent Ornament of this
renowned City, and one, who, by the Variety, and the happy Success, of his
negotiations, has given evident proofs, that he is not easie to be deceiv’d.
This Gentleman has well observ’d, that the Arts of life have been too long
imprison’d in the dark shops of Mechanicks themselves, & there hindred
from growth, either by ignorance, or self-interest: and he has bravely freed
them from these inconveniences: He hath not only obliged Tradesmen, but
Trade it self: He has done a work that is worthy of London, and has taught
the chief City of Commerce in the world the right way how Commerce is to
be improv’d. We have already seen many other great signs of Liberality and
a large mind, from the same hand: For by his diligence about the
Corporation for the Poor; by his honorable Subscriptions for the rebuilding
of St. Paul’s; by his chearful Disbursment for the replanting of Ireland, and
by many other such publick works, he has shewn by what means he
indeavours to establish his Memory; and now by this last gift he has done
that, which became one of the wisest Citizens of our Nation to accomplish,
seeing one of the wisest of our Statesmen, the Lord Verulam, first
propounded it.
But to return to my Subject, from a digression, which, I hope, my Reader
will pardon me, seeing the Example is so rare that I can make no more such
digressions. If these my first Labours shall be any wayes useful to inquiring
men, I must attribute the incouragement and promotion of them to a very
Reverend and Learned Person, of whom this ought in justice to be said,
That there is scarce any one Invention, which this Nation has produc’d in
our Age, but it has some way or other been set forward by his assistance.
My Reader, I believe, will quickly ghess, that it is Dr. Wilkins that I mean.
He is indeed a man born for the good of mankind, and for the honour of his
Country. In the sweetness of whose behaviour, in the calmness of his mind,
in the unbounded goodness of his heart, we have an evident Instance, what
the true and the primitive unpassionate Religion was, before it was sowred
by particular Factions. In a word, his Zeal has been so constant and
effectual in advancing all good and profitable Arts, that as one of the
Antient Romans said of Scipio, That he thanked God that he was a Roman;
because whereever Scipio had been born, there had been the seat of the
Empire of the world: So may I thank God, that Dr. Wilkins was an

Englishman, for whereever he had lived, there had been the chief Seat of
generous Knowledge and true Philosophy. To the truth of this, there are so
many worthy men living that will subscribe, that I am confident, what I have
here said, will not be looked upon, by any ingenious Reader, as a
Panegyrick, but only as a real testimony.
By the Advice of this Excellent man I first set upon this Enterprise, yet
still came to it with much Reluctancy, because I was to follow the footsteps
of so eminent a Person as Dr. Wren, who was the first that attempted any
thing of this nature; whose original draughts do now make one of the
Ornaments of that great Collection of Rarities in the Kings Closet. This
Honor, which his first beginnings of this kind have receiv’d, to be admitted
into the most famous place of the world, did not so much incourage, as the
hazard of coming after Dr. Wren did affright me; for of him I must affirm,
that, since the time of Archimedes, there scarce ever met in one man, in so
great a perfection, such a Mechanical Hand, and so Philosophical a Mind.
But at last, being assured both by Dr. Wilkins, and Dr. Wren himself, that
he had given over his intentions of prosecuting it, and not finding that there
was any else design’d the pursuing of it, I set upon this undertaking, and
was not a little incourag’d to proceed in it, by the Honour the Royal
Society was pleas’d to favour me with, in approving of those draughts
(which from time to time as I had an opportunity of describing) I presented
to them. And particularly by the Incitements of divers of those Noble and
excellent Persons of it, which were my more especial Friends, who were not
less urgent with me for the publishing, then for the prosecution of them.
After I had almost compleated these Pictures and Observations (having
had divers of them engraven, and was ready to send them to the Press) I
was inform’d, that the Ingenious Physitian Dr. Henry Power had made
several Microscopical Observations, which had I not afterwards, upon our
interchangably viewing each others Papers, found that they were for the
most part differing from mine, either in the Subject it self, or in the
particulars taken notice of; and that his design was only to print
Observations without Pictures, I had even then suppressed what I had so far
proceeded in. But being further excited by several of my Friends, in
compliance with their opinions, that it would not be unacceptable to several
inquisitive Men, and hoping also, that I should thereby discover something

New to the World, I have at length cast in my Mite, into the vast Treasury of
A Philosophical History. And it is my hope, as well as belief, that these my
Labours will be no more comparable to the Productions of many other
Natural Philosophers, who are now every where busie about greater things;
then my little Objects are to be compar’d to the greater and more beautiful
Works of Nature, A Flea, a Mite, a Gnat, to an Horse, an Elephant, or a
Lyon.

MICROGRAPHIA,
OR SOME

Physiological Descriptions

OF

MINUTE BODIES,
MADE BY

MAGNIFYING GLASSES;

WITH

OBSERVATIONS and INQUIRIES thereupon.

Observ. I. Of the Point of a sharp small Needle.

s in Geometry, the most natural way of beginning is
from a Mathematical point; so is the same method in Observations and
Natural history the most genuine, simple, and instructive. We must first
endevour to make letters, and draw single strokes true, before we venture to
write whole Sentences, or to draw large Pictures. And in Physical
Enquiries, we must endevour to follow Nature in the more plain and easie
ways she treads in the most simple and uncompounded bodies, to trace her
steps, and be acquainted with her manner of walking there, before we
venture our selves into the multitude of meanders she has in bodies of a
more complicated nature; lest, being unable to distinguish and judge of our
way, we quickly lose both Nature our Guide, and our selves too, and are left
to wander in the labyrinth of groundless opinions; wanting both judgment,
that light, and experience, that clew, which should direct our proceedings.
We will begin these our Inquiries therefore with the Observations of
Bodies of the most simple nature first, and so gradually proceed to those of
a more compounded one. In prosecution of which method, we shall begin
with a Physical point; of which kind the Point of a Needle is commonly
reckon’d for one; and is indeed, for the most part, made so sharp, that the
naked eye cannot distinguish any parts of it: It very easily pierces, and
makes its way through all kind of bodies softer then it self: But if view’d
with a very good Microscope, we may find that the top of a Needle (though
as to the sense very sharp) appears a broad, blunt, and very irregular end;
not resembling a Cone, as is imagin’d, but onely a piece of a tapering body,
with a great part of the top remov’d, or deficient. The Points of Pins are yet
more blunt, and the Points of the most curious Mathematical Instruments do
very seldome arrive at so great a sharpness; how much therefore can be
built upon demonstrations made onely by the productions of the Ruler and

Compasses, he will be better able to consider that shall but view those
points and lines with a Microscope.
Now though this point be commonly accounted the sharpest (whence
when we would express the sharpness of a point the most superlatively, we
say, As sharp as a Needle) yet the Microscope can afford us hundreds of
Instances of Points many thousand times sharper: such as those of the hairs,
and bristles, and claws of multitudes of Insects; the thorns, or crooks, or
hairs of leaves, and other small vegetables; nay, the ends of the stiriæ or
small parallelipipeds of Amianthus, and alumen plumosum; of many of
which, though the Points are so sharp as not to be visible, though view’d
with a Microscope (which magnifies the Object, in bulk, above a million of
times) yet I doubt not, but were we able practically to make Microscopes
according to the theory of them, we might find hills, and dales, and pores,
and a sufficient bredth, or expansion, to give all those parts elbow-room,
even in the blunt top of the very Point of any of these so very sharp bodies.
For certainly the quantity or extension of any body may be Divisible in
infinitum, though perhaps not the matter.
Schem. 2.
Fig. 1.

But to proceed: The Image we have here exhibited in the first Figure, was
the top of a small and very sharp Needle, whose point aa nevertheless
appear’d through the Microscope above a quarter of an inch broad, not
round nor flat, but irregular and uneven; so that it seem’d to have been big
enough to have afforded a hundred armed Mites room enough to be rang’d
by each other without endangering the breaking one anothers necks, by
being thrust off on either side. The surface of which, though appearing to
the naked eye very smooth, could not nevertheless hide a multitude of holes
and scratches and ruggednesses from being discover’d by the Microscope to
invest it, several of which inequalities (as A, B, C, seem’d holes made by
some small specks of Rust; and D some adventitious body, that stuck very
close to it) were casual. All the rest that roughen the surface, were onely so
many marks of the rudeness and bungling of Art. So unaccurate is it, in all
its productions, even in those which seem most neat, that if examin’d with
an organ more acute then that by which they were made, the more we see of
their shape, the less appearance will there be of their beauty: whereas in the
works of Nature, the deepest Discoveries shew us the greatest Excellencies.

An evident Argument, that he that was the Author of all these things, was no
other then Omnipotent; being able to include as great a variety of parts and
contrivances in the yet smallest Discernable Point, as in those vaster bodies
(which comparatively are called also Points) such as the Earth, Sun, or
Planets. Nor need it seem strange that the Earth it self may be by an
Analogie call’d a Physical Point: For as its body, though now so near us as
to fill our eys and fancies with a sense of the vastness of it, may by a little
Distance, and some convenient Diminishing Glasses, be made vanish into a
scarce visible Speck, or Point (as I have often try’d on the Moon, and (when
not too bright) on the Sun it self.) So, could a Mechanical contrivance
succesfully answer our Theory, we might see the least spot as big as the
Earth it self; and Discover, as Des Cartes also conjectures (Diop. ch. 10. §
9.), as great a variety of bodies in the Moon, or Planets, as in the Earth.
But leaving these Discoveries to future Industries, we shall proceed to
add one Observation more of a point commonly so call’d, that is, the mark
of a full stop, or period. And for this purpose I observed many both printed
ones and written; and among multitudes I found few of them more round or
Schem. 2.
Fig. 3. regular then this which I have delineated in the third figure of the
second Scheme, but very many abundantly more disfigur’d; and for the
most part if they seem’d equally round to the eye, I found those points that
had been made by a Copper-plate, and Roll-press, to be as misshapen as
those which had been made with Types, the most curious and smothly
engraven strokes and points, looking but as so many furrows and holes, and
their printed impressions, but like smutty daubings on a matt or uneven
floor with a blunt extinguisht brand or stick’s end. And as for points made
with a pen they were much more ragged and deformed. Nay, having view’d
certain pieces of exceeding curious writing of the kind (one of which in the
bredth of a two-pence compris’d the Lords prayer, the Apostles Creed, the
ten Commandments, and about half a dozen verses besides of the Bible,
whose lines were so small and near together, that I was unable to number
them with my naked eye,) a very ordinary Microscope, I had then about me,
inabled me to see that what the Writer of it had asserted was true, but
withall discover’d of what pitifull bungling scribbles and scrawls it was
compos’d, Arabian and China characters being almost as well shap’d, yet
thus much I must say for the Man, that it was for the most part legible

enough, though in some places there wanted a good fantsy well preposest to
help one through. If this manner of small writing were made easie and
practicable (and I think I know such a one, but have never yet made tryal of
it, whereby one might be inabled to write a great deale with much ease, and
accurately enough in a very little roome) it might be of very good use to
convey secret Intelligence without any danger of Discovery or mistrusting.
But to come again to the point. The Irregularities of it are caused by three
or four coadjutors, one of which is, the uneven surface of the paper, which
at best appears no smother then a very course piece of shag’d cloth, next the
irregularity of the Type or Ingraving, and a third is the rough Daubing of
the Printing-Ink that lies upon the instrument that makes the impression, to
all which, add the variation made by the Different lights and shadows, and
you may have sufficient reason to ghess that a point may appear much more
ugly then this, which I have here presented, which though it appear’d
through the Microscope gray, like a great splatch of London dirt, about
three inches over; yet to the naked eye it was black and no bigger then that
in the midst of the Circle A. And could I have found Room in this Plate to
have inserted an O you should have seen that the letters were not more
distinct then the points of Distinction, nor a drawn circle more exactly so,
then we have now shown a point to be a point.

Observ. II. Of the Edge of a Razor.
The sharpest Edge hath the same kind of affinity to the sharpest Point in
Physicks, as a line hath to a point in Mathematicks; and therefore the Treaty
concerning this, may very properly be annexed to the former. A Razor doth
appear to be a Body of a very neat and curious aspect, till more closely
viewed by the Microscope, and there we may observe its very Edge to be of
all kind of shapes, except what it should be. For examining that of a very
sharp one, I could not find that any part of it had any thing of sharpness in
it; but it appeared a rough surface of a very considerable bredth from side to
side, the narrowest part not seeming thinner then the back of a pretty thick
Knife. Nor is’t likely that it should appear any otherwise, since as we just
now shew’d that a point appear’d a circle, ’tis rational a line should be a
parallelogram.
Schem. 2.
Fig. 2.

Now for the drawing this second Figure (which represents a part of the
Edge about half a quarter of an inch long of a Razor well set) I so plac’d it
between the Object-glass & the light, that there appear’d a reflection from
the very Edge, represented by the white line abcdef. In which you may
perceive it to be somewhat sharper then elsewhere about d, to be indented
or pitted about b, to be broader and thicker about c, and unequal and rugged
about e, and pretty even between ab and ef. Nor was that part of the Edge
ghik so smooth as one would imagine so smooth bodies as a Hone and Oyl
should leave it; for besides those multitudes of scratches, which appear to
have raz’d the surface ghik, and to cross each other every way which are not
half of them exprest in the Figure, there were several great and deep
scratches, or furrows, such as gh and ik, which made the surface yet more
rugged, caus’d perhaps by some small Dust casually falling on the Hone, or
some harder or more flinty part of the Hone it self. The other part of the
Razor ll, which is polish’d on a grinding-stone, appear’d much rougher then
the other, looking almost like a plow’d field, with many parallels, ridges,
and furrows, and a cloddy, as ’twere, or an uneven surface: nor shall we
wonder at the roughnesses of those surfaces, since even in the most curious

wrought Glasses for Microscopes, and other Optical uses, I have, when the
Sun has shone well on them, discover’d their surface to be variously raz’d
or scratched, and to consist of an infinite of small broken surfaces, which
reflect the light of very various and differing colours. And indeed it seems
impossible by Art to cut the surface of any hard and brittle body smooth,
since Putte, or even the most curious Powder that can be made use of, to
polish such a body, must consist of little hard rough particles, and each of
them must cut its way, and consequently leave some kind of gutter or
furrow behind it. And though Nature does seem to do it very readily in all
kinds of fluid bodies, yet perhaps future observators may discover even
these also rugged; it being very probable, as I elsewhere shew, that fluid
bodies are made up of small solid particles variously and strongly mov’d,
and may find reason to think there is scarce a surface in rerum naturâ
perfectly smooth. The black spot mn, I ghess to be some small speck of rust,
for that I have oft observ’d to be the manner of the working of Corrosive
Juyces. To conclude, this Edge and piece of a Razor, if it had been really
such as it appear’d through the Microscope, would scarcely have serv’d to
cleave wood, much less to have cut off the hair of beards, unless it were
after the manner that Lucian merrily relates Charon to have made use of,
when with a Carpenters Axe he chop’d off the beard of a sage Philosopher,
whose gravity he very cautiously fear’d would indanger the oversetting of
his Wherry.

Observ. III. Of fine Lawn, or Linnen Cloth.
This is another product of Art, A piece of the finest Lawn I was able to
get, so curious that the threads were scarce discernable by the naked eye,
and yet through an ordinary Microscope you may perceive what a goodly
piece of coarse Matting it is; what proportionable cords each of its threads
are, being not unlike, both in shape and size, the bigger and coarser kind of
single Rope-yarn, wherewith they usually make Cables. That which makes
the Lawn so transparent, is by the Microscope, nay by the naked eye, if
attentively viewed, plainly enough evidenced to be the multitude of square
holes which are left between the threads, appearing to have much more hole
in respect of the intercurrent parts then is for the most part left in a lattice-
window, which it does a little resemble, onely the crossing parts are round
and not flat.
These threads that compose this fine contexture, though they are as small
as those that constitute the finer sorts of Silks, have notwithstanding
nothing of their glossie, pleasant, and lively reflection. Nay, I have been
informed both by the Inventor himself, and several other eye-witnesses, that
though the flax, out of which it is made, has been (by a singular art, of that
excellent Person, and Noble Virtuoso, M. Charls Howard, brother to the
Duke of Norfolk) so curiously dress’d and prepar’d, as to appear both to the
eye and the touch, full as fine and as glossie, and to receive all kinds of
colours, as well as Sleave-Silk; yet when this Silken Flax is twisted into
threads, it quite loseth its former luster, and becomes as plain and base a
thread to look on, as one of the same bigness, made of common Flax.
The reason of which odd Phenomenon seems no other then this; that
though the curiously drest Flax has its parts so exceedingly small, as to
equallize, if not to be much smaller then the clew of the Silk-worm,
especially in thinness, yet the differences between the figures of the
constituting filaments are so great, and their substances so various, that
whereas those of the Silk are small, round, hard, transparent, and to their
bigness proportionably stiff, so as each filament preserves its proper Figure,
and consequently its vivid reflection intire, though twisted into a thread, if

not too hard; those of Flax are flat, limber, softer, and less transparent, and
in twisting into a thread they joyn, and lie so close together, as to lose their
own, and destroy each others particular reflections. There seems therefore
three Particulars very requisite to make the so drest Flax appear Silk also
when spun into threads. First, that the substance of it should be made more
clear and transparent, Flax retaining in it a kind of opacating brown, or
yellow; and the parts of the whitest kind I have yet observ’d with the
Microscope appearing white, like flaw’d Horn or Glass, rather then clear,
like clear Horn or Glass. Next that, the filaments should each of them be
rounded, if that could be done, which yet is not so very necessary, if the
first be perform’d, and this third, which is, that each of the small filaments
be stifned; for though they be square, or flat, provided they be transparent
and stiff, much the same appearances must necessarily follow. Now, though
I have not yet made trial, yet I doubt not, but that both these proprieties may
be also induc’d upon the Flax, and perhaps too by one and the same
Expedient, which some trials may quickly inform any ingenious attempter
of, who from the use and profit of such an Invention, may find sufficient
argument to be prompted to such Inquiries. As for the tenacity of the
substance of Flax, out of which the thread is made, it seems much inferiour
to that of Silk, the one being a vegetable, the other an animal substance.
And whether it proceed from the better concoction, or the more
homogeneous constitution of animal substances above those of vegetables,
I do not here determine; yet since I generally find, that vegetable substances
do not equalize the tenacity of animal, nor these the tenacity of some
purified mineral substances; I am very apt to think, that the tenacity of
bodies does not proceed from the hamous, or hooked particles, as the
Epicureans and some modern Philosophers have imagin’d; but from the
more exact congruity of the constituent parts, which are contiguous to each
other, and so bulky, as not to be easily separated, or shatter’d, by any small
pulls or concussion of heat.

Observ. IV. Of fine waled Silk, or Taffety.
Schem. 3.
Fig. 1.

This is the appearance of a piece of very fine Taffety-riband in the bigger
magnifying Glass, which you see exhibits it like a very convenient
substance to make Bed-matts, or Door-matts of, or to serve for Beehives,
Corn-scuttles, Chairs, or Corn-tubs, it being not unlike that kind of work,
wherewith in many parts in England, they make such Utensils of Straw, a
little wreathed, and bound together with thongs of Brambles. For in this
Contexture, each little filament, fiber, or clew of the Silk-worm, seem’d
about the bigness of an ordinary Straw, as appears by the little irregular
pieces, ab, cd, and ef; The Warp, or the thread that ran crossing the Riband,
appear’d like a single Rope of an Inch Diameter; but the Woof, or the thread
that ran the length of the Riband, appear’d not half so big. Each Inch of six-
peny-broad Riband appearing no less then a piece of Matting Inch and half
thick, and twelve foot square, a few yards of this, would be enough to floor
the long Gallery of the Loure at Paris. But to return to our piece of Riband:
It affords us a not unpleasant object, appearing like a bundle, or wreath, of
very clear and transparent Cylinders, if the Silk be white, and curiously
ting’d; if it be colour’d, each of those small horney Cylinders affording in
some place or other of them, as vivid a reflection, as if it had been sent from
a Cylinder of Glass or Horn. Insomuch, that the reflections of Red, appear’d
as if coming from so many Granates, or Rubies. The loveliness of the
colours of Silks above those of hairy Stuffs, or Linnen, consisting, as I else-
where intimate, chiefly in the transparency, and vivid reflections from the
Concave, or inner surface of the transparent Cylinder, as are also the
colours of Precious Stones; for most of the reflections from each of these
Cylinders, come from the Concave surface of the air, which is as ’twere the
foil that incompasses the Cylinder. The colours with which each of these
Cylinders are ting’d, seem partly to be superficial, and sticking to the out-
sides of them; and partly, to be imbib’d, or sunck into the substance of
them: for Silk, seeming to be little else then a dried thread of Glew, may be
suppos’d to be very easily relaxt, and softened, by being steeped in warm,

nay in cold, if penetrant, juyces or liquors. And thereby those tinctures,
though they tinge perhaps but a small part of the substance, yet being so
highly impregnated with the colour, as to be almost black with it, may leave
an impression strong enough to exhibite the desir’d colour. A pretty kinde
of artificial Stuff I have seen, looking almost like transparent Parchment,
Horn, or Ising-glass, and perhaps some such thing it may be made of, which
being transparent, and of a glutinous nature, and easily mollified by keeping
in water, as I found upon trial, had imbib’d, and did remain ting’d with a
great variety of very vivid colours, and to the naked eye, it look’d very like
the substance of the Silk. And I have often thought, that probably there
might be a way found out, to make an artificial glutinous composition,
much resembling, if not full as good, nay better, then that Excrement, or
whatever other substance it be out of which, the Silk-worm wire-draws his
clew. If such a composition were found, it were certainly an easie matter to
find very quick ways of drawing it out into small wires for use. I need not
mention the use of such an Invention, nor the benefit that is likely to accrue
to the finder, they being sufficiently obvious. This hint therefore, may, I
hope, give some Ingenious inquisitive Person an occasion of making some
trials, which if successfull, I have my aim, and I suppose he will have no
occasion to be displeas’d.

Observ. V. Of watered Silks, or Stuffs.
There are but few Artificial things that are worth observing with a
Microscope, and therefore I shall speak but briefly concerning them. For the
Productions of art are such rude mis-shapen things, that when view’d with a
Microscope, is little else observable, but their deformity. The most curious
Carvings appearing no better then those rude Russian Images we find
mention’d in Purchas, where three notches at the end of a Stick, stood for a
face. And the most smooth and burnish’d surfaces appear most rough and
unpolisht: So that my first Reason why I shall add but a few observations of
them, is, their mis-shapen form; and the next, is their uselessness. For why
should we trouble our selves in the examination of that form or shape
(which is all we are able to reach with a Microscope) which we know was
design’d for no higher a use, then what we were able to view with our
naked eye? Why should we endeavour to discover mysteries in that which
has no such thing in it? And like Rabbins find out Caballisms, and ænigmâs
in the Figure, and placing of Letters, where no such thing lies hid: whereas
in natural forms there are some so small, and so curious, and their design’d
business so far remov’d beyond the reach of our sight, that the more we
magnify the object, the more excellencies and mysteries do appear; And the
more we discover the imperfections of our senses; and the Omnipotency
and Infinite perfections of the great Creatour. I shall therefore onely add one
or two Observations more artificial things, and then come to the Treaty
concerning such matters as are the Productions of a more curious Workman.
One of these, shall be that of a piece of water’d Silk, Schem. 3.
Fig. 2. represented in the second Figure of the third Scheme, as it appear’d
through the least magnifying Glass. AB signifying the long way of the Stuff,
and CD the broad way. This Stuff, if the right side of it be looked upon,
appears to the naked eye, all over so waved, undulated, or grain’d, with a
curious, though irregular variety of brighter and darker parts, that it adds no
small gracefulness to the Gloss of it. It is so known a propriety, that it needs
but little explication, but it is observable, which perhaps everyone has not
considered, that those parts which appear the darker part of the wave, in one
position to the light, in another appears the lighter, and the contrary; and by

this means the undulations become transient, and in a continual change,
according as the position of the parts in respect of the incident beams of
light is varied. The reason of which odd phænomena, to one that has but
diligently examin’d it even with his naked eye, will be obvious enough. But
he that observes it with a Microscope, may more easily perceive what this
Proteus is, and how it comes to change its shape. He may very easily
perceive, that it proceeds onely from the variety of the Reflections of light,
which is caus’d by the various shape of the Particles, or little protuberant
parts of the thread that compose the surface; and that those parts of the
waves that appear the brighter, throw towards the eye a multitude of small
reflections of light, whereas the darker scarce afford any. The reason of
which reflection, the Microscope plainly discovers, as appears by the
Figure. In which you may perceive, that the brighter parts of the surface
consist of an abundance of large and strong reflections, denoted by a, a, a,
a, a, &c. for the surfaces of those threads that run the long way, are by the
Mechanical process of watering, creas’d or angled in another kind of
posture then they were by the weaving: for by the weaving they are onely
bent round the warping threads; but by the watering, they are bent with an
angle, or elbow, that is in stead of lying, or being bent round the threads, as
in the third Figure, a, a, a, a, a, are about b, b, b (b, b, b representing the
ends, as ’twere, of the cross threads, they are bent about) they are creas’d on
the top of those threads, with an angle, as in the fourth Figure, and that with
all imaginable variety; so that, whereas before they reflected the light onely
from one point of the round surface, as about c, c, c, they now when
water’d, reflect the beams from more then half the whole surface, as de, de,
de, and in other postures they return no reflections at all from those
surfaces. Hence in one posture they compose the brighter parts of the
waves, in another the darker. And these reflections are also varied,
according as the particular parts are variously bent. The reason of which
creasing we shall next examine; and here we must fetch our information
from the Mechanism or manner of proceeding in this operation; which, as I
have been inform’d, is no other then this.
They double all the Stuff that is to be water’d, that is, they crease it just
through the middle of it, the whole length of the piece, leaving the right side
of the Stuff inward, and placing the two edges, or silvages just upon one
another, and, as near as they can, place the wale so in the doubling of it, that

the wale of the one side may lie very near parallel, or even with the wale of
the other; for the nearer that posture they lie, the greater will the watering
appear; and the more obliquely, or across to each other they lie, the smaller
are the waves. Their way for folding it for a great wale is thus: they take a
Pin, and begin at one side of the piece in any wale, and so moving it
towards the other side, thereby direct their hands to the opposite ends of the
wale, and then, as near as they can, place the two opposite ends of the same
wale together, and so double, or fold the whole piece, repeating this enquiry
with a Pin at every yard or two’s distance through the whole length; then
they sprinkle it with water, and fold it the long-ways, placing between every
fold a piece of Pastboard, by which means all the wrong side of the water’d
Stuff becomes flat, and with little wales, and the wales on the other side
become the more protuberant; whence the creasings or angular bendings of
the wales become the more perspicuous. Having folded it in this manner,
they place it with an interjacent Pastboard into an hot Press, where it is kept
very violently prest, till it be dry and stiff; by which means, the wales of
either contiguous sides leave their own impressions upon each other, as is
very manifest by the second Figure, where ’tis obvious enough, that the
wale of the piece ABCD runs parallel between the pricked lines ef, ef, ef,
and as manifest to discern the impressions upon these wales, left by those
that were prest upon them, which lying not exactly parallel with them, but a
little athwart them, as is denoted by the lines of, oooo, gh, gh, gh, between
which the other wales did lie parallel; they are so variously, and irregularly
creas’d that being put into that shape when wet, and kept so till they be drie,
they so let each others threads, that the Moldings remain almost as long as
the Stuff lasts.
Hence it may appear to any one that attentively considers the Figure, why
the parts of the wale a, a, a, a, a, a, should appear bright; and why the parts
b, b, b, b, b, b, b, should appear shadowed, or dark; why some, as d, d, d, d,
d, d, should appear partly light, and partly dark: the varieties of which
reflections and shadows are the only cause of the appearance of watering in
Silks, or any other kind of Stuffs.
From the variety of reflection, may also be deduc’d the cause why a
small breez or gale of wind ruffling the surface of a smooth water, makes it
appear black; as also, on the other side, why the smoothing or burnishing
the surface of whitened Silver makes it look black; and multitudes of other

phænomena might hereby be solv’d, which are too many to be here insisted
on.

Observ. VI. Of Small Glass Canes.
That I might be satisfi’d, whether it were not possible to make an
Artificial pore as small as any Natural I had yet found, I made several
attempts with small glass pipes, melted in the flame of a Lamp, and then
very suddenly drawn out into a great length. And, by that means, without
much difficulty, I was able to draw some almost as small as a Cobweb,
which yet, with the Schem. 4. Microscope, I could plainly perceive to be
perforated, both by looking on the ends of it, and by looking on it against
the light which was much the easier way to determine whether it were solid
or perforated; for, taking a small pipe of glass, and closing one end of it,
then filling it half full of water, and holding it against the light, I could, by
this means, very easily find what was the differing aspect of a solid and a
perforated piece of glass; and so easily distinguish, without seeing either
end, whether any Cylinder of glass I look’d on, were a solid stick, or a
hollow cane. And by this means, I could also presently judge of any small
filament of glass, whether it were hollow or not, which would have been
exceeding tedious to examine by looking on the end. And many such like
ways I was fain to make use of, in the examining of divers other particulars
related in this Book, which would have been no easie task to have
determined meerly by the more common way of looking on, or viewing the
Object. For, if we consider first, the very faint light wherewith the object is
enlightened, whence many particles appear opacous, which when more
enlightned, appear very transparent, so that I was fain to determine its
transparency by one glass, and its texture by another. Next, the
unmanageableness of most Objects, by reason of their smalness, 3. The
difficulty of finding the desired point, and of placing it so, as to reflect the
light conveniently for the Inquiry. Lastly, ones being able to view it but with
one eye at once, they will appear no small obstructions, nor are they easily
remov’d without many contrivances. But to proceed, I could not find that
water, or some deeply ting’d liquors would in small ones rise so high as one
would expect; and the highest I have found it yet rise in any of the pipes I
have try’d, was to 21 inches above the level of the water in the vessel: for
though I found that in the small pipes it would nimbly enter at first, and run

about 6 or 7 inches upwards; yet I found it then to move upwards so slow,
that I have not yet had the patience to observe it above that height of 21
inches (and that was in a pretty large Pipe, in comparison of those I
formerly mentioned; for I could observe the progress of a very deep ting’d
liquor in it with my naked eye, without much trouble; whereas many of the
other pipes were so very small, that unless in a convenient posture to the
light, I could not perceive them:) But ’tis very probable, that a greater
patience and assiduity may discover the liquors to rise, at least to remain
suspended, at heights that I should be loath now even to ghess at, if at least
there be any proportion kept between the height of the ascending liquor,
and the bigness of the holes of the pipes.
An Attempt for the Explication of this Experiment.
My Conjecture, That the unequal height of the surfaces of the water,
proceeded from the greater pressure made upon the water by the Air Schem. 4.
Fig. 1. without the Pipes ABC, then by that within them; I shall endeavour to
confirm from the truth of the two following Propositions:
The first of which is, That an unequal pressure of the incumbent Air, will
cause an unequal height in the water’s Surfaces.
And the second is, That in this experiment there is such an unequal
pressure.
That the first is true, the following Experiment will evince. For if you
take any Vessel so contrived, as that you can at pleasure either increase or
diminish the pressure of the Air upon this or that part of the Superficies of
the water, the equality of the height of those parts will presently be lost; and
that part of the Superficies that sustains the greater pressure, will be inferior
to that which undergoes the less. A fit Vessel for this purpose, will be an
inverted Glass Syphon, such an one as is described in the Sixth Figure. For
if into it you put Water enough to fill it as high as AB, and gently blow in at
D, you shall depress the Superficies B, and thereby raise the opposite
Superficies A to a considerable height, and by gently sucking you may
produce clean contrary effects.
Next, That there is such an unequal pressure, I shall prove from this, That
there is a much greater incongruity of Air to Glass, and some other Bodies,

then there is of Water to the same.
By Congruity, I mean a property of a fluid Body, whereby any part of it is
readily united with any other part, either of itself, or of any other Similar,
fluid, or solid body: And by Incongruity a property of a fluid, by which it is
hindred from uniting with any dissimilar, fluid, or solid Body.
This last property, any one that hath been observingly conversant about
fluid Bodies, cannot be ignorant of. For (not now to mention several
Chymical Spirits and Oyls, which will very hardly, if at all, be brought to
mix with one another; insomuch that there may be found some 8 or 9, or
more, several distinct Liquors, which swimming one upon another, will not
presently mix) we need seek no further for Examples of this kind in fluids,
then to observe the drops of rain falling through the air and the bubbles of
air which are by any means conveyed under the surface of the water; or a
drop of common Sallet Oyl swimming upon water. In all which, and many
more examples of this kind that might be enumerated, the incongruity of
two fluids is easily discernable. And as for the Congruity or Incongruity of
Liquids, with several kinds of firm Bodies, they have long since been taken
notice of, and called by the Names of Driness and Moisture (though these
two names are not comprehensive enough, being commonly used to signifie
only the adhering or not adhering of water to some other solid Bodies) of
this kind we may observe that water will more readily wet some woods then
others; and that water, let fall upon a Feather, the whiter side of a Colwort,
and some other leaves, or upon almost any dusty, unctuous, or resinous
superficies, will not at all adhere to them, but easily tumble off from them,
like a solid Bowl; whereas, if dropt upon Linnen, Paper, Clay, green Wood,
&c. it will not be taken off, without leaving some part of it behind adhering
to them. So Quick-silver, which will very hardly be brought to stick to any
vegetable body, will readily adhere to, and mingle with, several clean
metalline bodies.
And that we may the better finde what the cause of Congruity and
Incongruity in bodies is, it will be requisite to consider, First, what is the
cause of fluidness; And this, I conceive, to be nothing else but a certain
pulse or shake of heat; for Heat being nothing else but a very brisk and
vehement agitation of the parts of a body (as I have elswhere made
probable) the parts of a body are thereby made so loose from one another,

that they easily move any way, and become fluid. That I may explain this a
little by a gross Similitude, let us suppose a dish of sand set upon some
body that is very much agitated, and shaken with some quick and strong
vibrating motion, as on a Milstone turn’d round upon the under stone very
violently whilst it is empty; or on a very stiff Drum-head, which is
vehemently or very nimbly beaten with the Drumsticks. By this means, the
sand in the dish, which before lay like a dull and unactive body, becomes a
perfect fluid; and ye can no sooner make a hole in it with your finger, but it
is immediately filled up again, and the upper surface of it levell’d. Nor can
you bury a light body, as a piece of Cork under it, but it presently emerges
or swims as ’twere on the top; nor can you lay a heavier on the top of it, as a
piece of Lead, but it is immediately buried in Sand, and (as ’twere) sinks to
the bottom. Nor can you make a hole in the side of the Dish, but the sand
shall run out of it to a level, not an obvious property of a fluid body, as
such, but this dos imitate; and all this meerly caused by the vehement
agitation of the conteining vessel; for by this means, each sand becomes to
have a vibrative or dancing motion, so as no other heavier body can rest on
it, unless sustein’d by some other on either side: Nor will it suffer any Body
to be beneath it, unless it be a heavier then it self. Another Instance of the
strange loosening nature of a violent jarring Motion, or a strong and nimble
vibrative one, we may have from a piece of iron grated on very strongly
with a file: for if into that a pin screw’d so firm and hard, that though it has
a convenient head to it, yet it can by no means be unscrew’d by the fingers;
if, I say, you attempt to unscrew this whilst grated on by the file, it will be
found to undoe and turn very easily. The first of these Examples manifests,
how a body actually divided into small parts, becomes a fluid. And the latter
manifests by what means the agitation of heat so easily loosens and unties
the parts of solid and firm bodies. Nor need we suppose heat to be any thing
else, besides such a motion; for supposing we could Mechanically produce
such a one quick and strong enough, we need not spend fuel to melt a body.
Now, that I do not speak this altogether groundless, I must refer the Reader
to the Observations I have made upon the shining sparks of Steel, for there
he shall find that the same effects are produced upon small chips or parcels
of Steel by the flame, and by a quick and violent motion; and if the body of
steel may be thus melted (as I there shew it may) I think we have little
reason to doubt that almost any other may not also. Every Smith can inform
one how quickly both his File and the Iron grows hot with filing, and if you

rub almost any two hard bodies together, they will do the same: And we
know, that a sufficient degree of heat causes fluidity, in some bodies much
sooner, and in others later; that is, the parts of the body of some are so loose
from one another, and so unapt to cohere, and so minute and little, that a
very small degree of agitation keeps them always in the state of fluidity. Of
this kind, I suppose, the Æther, that is the medium or fluid body, in which
all other bodies do as it were swim and move; and particularly, the Air,
which seems nothing else but a kind of tincture or solution of terrestrial and
aqueous particles dissolv’d into it, and agitated by it, just as the tincture of
Cocheneel is nothing but some finer dissoluble parts of that Concrete lick’d
up or dissolv’d by the fluid water. And from this Notion of it, we may easily
give a more Intelligible reason how the Air becomes so capable of
Rarefaction and Condensation. For, as in tinctures, one grain of some
strongly tinging substance may sensibly colour some hundred thousand
grains of appropriated Liquors, so as every drop of it has its proportionate
share, and be sensibly ting’d, as I have try’d both with Logwood and
Cocheneel: And as some few grains of Salt is able to infect as great a
quantity, as may be found by præcipitations, though not so easily by the
sight or taste; so the Air, which seems to be but as ’twere a tincture or
saline substance, dissolv’d and agitated by the fluid and agil Æther, may
disperse and expand it self into a vast space, if it have room enough, and
infect, as it were, every part of that space. But, as on the other side, if there
be but some few grains of the liquor, it may extract all the colour of the
tinging substance, and may dissolve all the Salt, and thereby become much
more impregnated with those substances, so may all the air that sufficed in
a rarify’d state to fill some hundred thousand spaces of Æther, be
compris’d in only one, but in a position proportionable dense. And though
we have not yet found out such strainers for Tinctures and Salts as we have
for the Air, being yet unable to separate them from their dissolving liquors
by any kind of filtre, without præcipitation, as we are able to separate the
Air from the Æther by Glass, and several other bodies. And though we are
yet unable and ignorant of the ways of præcipitating Air out of the Æther as
we can Tinctures, and Salts out of several dissolvents; yet neither of these
seeming impossible from the nature of the things, nor so improbable but
that some happy future industry may find out ways to effect them; nay,
further, since we find that Nature does really perform (though by what
means we are not certain) both these actions, namely, by præcipitating the

Air in Rain and Dews, and by supplying the Streams and Rivers of the
World with fresh water, strain’d through secret subterraneous Caverns: And
since, that in very many other proprieties they do so exactly seem of the
same nature; till further observations or tryals do inform us of the contrary,
we may safely enough conclude them of the same kind. For it seldom
happens that any two natures have so many properties coincident or the
same, as I have observ’d Solutions and Air to have, and to be different in
the rest. And therefore I think it neither impossible, irrational, nay nor
difficult to be able to predict what is likely to happen in other particulars
also, besides those which Observation or Experiment have declared thus or
thus; especially, if the circumstances that do often very much conduce to the
variation of the effects be duly weigh’d and consider’d. And indeed, were
there not a probability of this, our inquiries would be endless, our tryals
vain, and our greatest inventions would be nothing but the meer products of
chance, and not of Reason; and, like Mariners in an Ocean, destitute both
of a Compass and the sight of the Celestial guides, we might indeed, by
chance, Steer directly towards our desired Port, but ’tis a thousand to one
but we miss our aim. But to proceed, we may hence also give a plain
reason, how the Air comes to be darkned by clouds, &c. which are nothing
but a kind of precipitation, and how those precipitations fall down in
Showrs. Hence also could I very easily, and I think truly, deduce the cause
of the curious sixangular figures of Snow, and the appearances of Haloes,
&c. and the sudden thickning of the Sky with Clouds, and the vanishing and
disappearing of those Clouds again; for all these things may be very easily
imitated in a glass of liquor, with some slight Chymical preparations as I
have often try’d, and may somewhere else more largely relate, but have not
now time to set them down. But to proceed, there are other bodies that
consist of particles more Gross, and of a more apt figure for cohesion, and
this requires somewhat greater agitation; such, I suppose , fermented
vinous Spirits, several Chymical Oils, which are much of kin to those
Spirits, &c. Others yet require a greater, as water, and so others much
greater, for almost infinite degrees: For, I suppose there are very few bodies
in the world that may not be made aliquatenus fluid, by some or other
degree of agitation or heat.
Having therefore in short set down my Notion of a Fluid body, I come in
the next place to consider what Congruity is; and this, as I said before,

being a Relative property of a fluid, whereby it may be said to be like or
unlike to this or that other body, whereby it does or does not mix with this or
that body. We will again have recourse to our former Experiment, though
but a rude one; and here if we mix in the dish several kinds of sands, some
of bigger, others of less and finer bulks, we shall find that by the agitation
the fine sand will eject and throw out of it self all those bigger bulks of
small stones and the like, and those will be gathered together all into one
place; and if there be other bodies in it of other natures, those also will be
separated into a place by themselves, and united or tumbled up together.
And though this do not come up to the highest property of Congruity, which
is a Cohæsion of the parts of the fluid together, or a kind of attraction and
tenacity, yet this does as ’twere shadow it out, and somewhat resemble it;
for just after the same manner, I suppose the pulse of heat to agitate the
small parcels of matter, and those that are of a like bigness, and figure, and
matter, will hold, or dance together, and those which are of a differing kind
will be thrust or shov’d out from between them; for particles that are
similar, will, like so many equal musical strings equally stretcht, vibrate
together in a kind of Harmony or unison; whereas others that are dissimilar,
upon what account soever, unless the disproportion be otherwise counter-
ballanc’d, will, like so many strings out of tune to those unisons, though
they have the same agitating pulse, yet make quite differing kinds of
vibrations and repercussions, so that though they may be both mov’d, yet
are their vibrations so different, and so untun’d, as ’twere to each other, that
they cross and jar against each other, and consequently, cannot agree
together, but fly back from each other to their similar particles. Now, to give
you an instance how the disproportion of some bodies in one respect, may
be counter-ballanc’d by a contrary disproportion of the same body in
another respect, whence we find that the subtil vinous spirit is congruous,
or does readily mix with water, which in many properties is of a very
differing nature, we may consider that a unison may be made either by two
strings of the same bigness, length, and tension, or by two strings of the
same bigness, but of differing length, and a contrary differing tension, or
3ly. by two strings of unequal length and bigness, and of a differing tension,
or of equal length, and differing bigness and tension, and several other such
varieties. To which three properties in strings, will correspond three
proprieties also in sand, or the particles of bodies, their Matter or
Substance, their Figure or Shape, and their Body or Bulk. And from the

varieties of these three, may arise infinite varieties in fluid bodies, though
all agitated by the same pulse or vibrative motion. And there may be as
many ways of making Harmonies and Discords with these, as there may be
with musical strings. Having therefore seen what is the cause of Congruity
or Incongruity, those relative properties of fluids, we may, from what has
been said, very easily collect, what is the reason of those Relative
proprieties also between fluid bodies and solid; for since all bodies consist
of particles of such a Substance, Figure, and Bulk; but in some they are
united together more firmly then to be loosened from each other by every
vibrative motion (though I imagine that there is no body in the world, but
that some degree of agitation may, as I hinted before, agitate and loosen the
particles so as to make them fluid) those cohering particles may vibrate in
the same manner almost as those that are loose and become unisons or
discords, as I may so speak, to them. Now that the parts of all bodies,
though never so solid, do yet vibrate, I think we need go no further for
proof, then that all bodies have some degrees of heat in them, and that there
has not been yet found any thing perfectly cold: Nor can I believe indeed
that there is any such thing in Nature, as a body whose particles are at rest,
or lazy and unactive in the great Theatre of the World, it being quite
contrary to the grand Oeconomy of the Universe. We see therefore what is
the reason of the sympathy or uniting of some bodies together, and of the
antipathy or flight of others from each other: For Congruity seems nothing
else but a Sympathy, and Incongruity an Antipathy of bodies, hence similar
bodies once united will not easily part, and dissimilar bodies once disjoyn’d
will not easily unite again; from hence may be very easily deduc’d the
reason of the suspension of water and Quick-silver above their usual
station, as I shall more at large anon shew.
These properties therefore (alwayes the concomitants of fluid bodies)
produce these following visible Effects:
First, They unite the parts of a fluid to its similar Solid, or keep them
separate from its dissimilar. Hence Quick-silver will (as we noted before)
stick to Gold, Silver, Tin, Lead, &c. and unite with them: but roul off from
Wood, Stone, Glass, &c. if never so little scituated out of its horizontal
level; and water that will wet salt and dissolve it, will slip off from Tallow,
or the like, without at all adhering; as it may likewise be observed to do
upon a dusty superficies. And next they cause the parts of homogeneal fluid

bodies readily to adhere together and mix, and of heterogeneal, to be
exceeding averse thereunto. Hence we find, that two small drops of water,
on any superficies they can roul on, will, if they chance to touch each other,
readily unite and mix into one 3d drop: The like may be observed with two
small Bowls of Quick-silver upon a Table or Glass, provided their surfaces
be not dusty; and with two drops of Oyl upon fair water, &c. And further,
water put unto wine, salt water, vinegar, spirit of wine, or the like, does
immediately (especially if they be shaken together) disperse it self all over
them. Hence, on the contrary, we also find, that Oyl of Tartar poured upon
Quick-silver, and Spirit of Wine on that Oyl, and Oyl of Turpentine on that
Spirit, and Air upon that Oyl, though they be stopt closely up into a Bottle,
and shaken never so much, they will by no means long suffer any of their
bigger parts to be united or included within any of the other Liquors (by
which recited Liquors, may be plainly enough represented the four
Peripatetical Elements, and the more subtil Æther above all.) From this
property ’tis, that a drop of water does not mingle with, or vanish into Air,
but is driven (by that Fluid equally protruding it on every side) and forc’t
into as little a space as it can possibly be contained in, namely, into a Round
Globule. So likewise a little Air blown under the water, is united or thrust
into a Bubble by the ambient water. And a parcel of Quick-silver enclosed
with Air, Water, or almost any other Liquor, is formed into a round Ball.
Now the cause why all these included Fluids, newly mentioned, or as
many others as are wholly included within a heterogeneous fluid, are not
exactly of a Spherical Figure (seeing that if caused by these Principles only,
it could be of no other) must proceed from some other kind of pressure
against the two opposite flatted sides. This adventitious or accidental
pressure may proceed from divers causes, and accordingly must diversifie
the Figure of the included heterogeneous fluid: For seeing that a body may
be included either with a fluid only, or only with a solid, or partly with a
fluid, and partly with a solid, or partly with one fluid, and partly with
another; there will be found a very great variety of the terminating surfaces,
much differing from a Spherical, according to the various resistance or
pressure that belongs to each of these encompassing bodies.
Which Properties may in general be deduced from two heads, viz.
Motion, and Rest. For, either this Globular Figure is altered by a natural
Motion, such as is Gravity, or a violent, such as is any accidental motion of

the fluids, as we see in the wind ruffling up the water, and the purlings of
Streams, and foaming of Catarracts, and the like. Or thirdly, By the Rest,
Firmness and Stability of the ambient Solid. For if the including Solid be of
an angular or any other irregular Form, the included fluid will be near of
the like, as a Pint-Pot full of water, or a Bladder full of Air. And next, if the
including or included fluid have a greater gravity one than another, then will
the globular Form be deprest into an Elliptico-spherical: As if, for example,
we suppose the Circle ABCD, in the fourth Figure, to represent a drop of
water, Quick-silver, or the like, included with the Air or the like, which
supposing there were no gravity at all in either of the fluids, or that the
contained and containing were of the same weight, would be equally
comprest into an exactly spherical body (the ambient fluid forcing equally
against every side of it.) But supposing either a greater gravity in the
included, by reason whereof the parts of it being prest from A towards B,
and thereby the whole put into motion, and that motion being hindred by the
resistance of the subjacent parts of the ambient, the globular Figure ADBC
will be deprest into the Elliptico-spherical, EGFH. For the side A is
detruded to E by the Gravity, and B to F by the resistance of the subjacent
medium: and therefore C must necessarily be thrust to G; and D to H. Or
else, supposing a greater gravity in the ambient, by whose more then
ordinary pressure against the under side of the included globule; B will be
forced to F, and by its resistance of the motion upwards, the side A will be
deprest to E, and therefore C being thrust to G and D to H; the globular
Figure by this means also will be made an Elliptico-spherical. Next if a
fluid be included partly with one, and partly with another fluid, it will be
found to be shaped diversly, according to the proportion of the gravity and
incongruity of the 3 fluids one to another: As in the second Figure, let the
upper MMM be Air, the middle LMNO be common Oyl, the lower OOO be
Water, the Oyl will be form’d, not into a spherical Figure, such as is
represented by the pricked Line, but into such a Figure as LMNO, whose
side LMN will be of a flatter Elliptical Figure, by reason of the great
disproportion between the Gravity of Oyl and Air, and the side LOM of a
rounder, because of the smaller difference between the weight of Oyl and
Water. Lastly, The globular Figure will be changed, if the ambient be partly
fluid and partly solid. And here the termination of the incompassed fluid
towards the incompassing is shap’d according to the proportion of the
congruity or incongruity of the fluids to the solids, and of the gravity and

incongruity of the fluids one to another. As suppose the subjacent medium
that hinders an included fluids descent, be a solid, as let KI, in the fourth
Figure, represent the smooth superficies of a Table; EGFH, a parcel of
running Mercury; the side GFH will be more flatted, according to the
proportion of the incongruity of the Mercury and Air to the Wood, and of
the gravity of Mercury and Air one to another; The side GEH will likewise
be a little more deprest by reason the subjacent parts are now at rest, which
were before in motion.
Or further in the third figure, let AILD represent an including solid
medium of a cylindrical shape (as suppose a small Glass Jar) Let FGEMM
represent a contain’d fluid, as water; this towards the bottom and sides, is
figured according to the concavity of the Glass: But its upper Surface,
(which by reason of its gravity, (not considering at all the Air above it, and
so neither the congruity or incongruity of either of them to the Glass)
should be terminated by part of a Sphere whose diameter should be the
same with that of the earth, which to our sense would appear a straight Line,
as FGE, Or which by reason of its having a greater congruity to Glass than
Air has, (not considering its Gravity) would be thrust into a concave Sphere,
as CHB, whose diameter would be the same with that of the concavity of
the Vessel:) Its upper Surface, I say, by reason of its having a greater gravity
then the Air, and having likewise a greater congruity to Glass then the Air
has, is terminated, by a concave Elliptico-spherical Figure, as CKB. For by
its congruity it easily conforms it self, and adheres to the Glass, and
constitutes as it were one containing body with it, and therefore should
thrust the contained Air on that side it touches it, into a spherical Figure, as
BHC, but the motion of Gravity depressing a little the Corners B and C,
reduces it into the aforesaid Figure CKB. Now that it is the greater
congruity of one of the two contiguous fluids, then of the other, to the
containing solid, that causes the separating surfaces to be thus or thus
figured: And that it is not because this or that figurated surface is more
proper, natural, or peculiar to one of these fluid bodies, then to the other,
will appear from this; that the same fluids will by being put into differing
solids, change their surfaces. For the same water, which in a Glass or
wooden Vessel will have a concave surface upwards, and will rise higher in
a smaller then a greater Pipe, the same water, I say, in the same Pipes
greased over or oyled, will produce quite contrary effects; for it will have a

protuberant and convex surface upwards, and will not rise so high in small,
as in bigger Pipes: Nay, in the very same solid Vessel, you may make the
very same two contiguous Liquids to alter their Surfaces; for taking a small
Wine-glass, or such like Vessel, and pouring water gently into it, you shall
perceive the surface of the water all the way concave, till it rise even with
the top, when you shall find it (if you gently and carefully pour in more) to
grow very protuberant and convex; the reason of which is plain, for that the
solid sides of the containing body are no longer extended, to which the
water does more readily adhere then the air; but it is henceforth to be
included with air, which would reduce it into a hemisphere, but by reason of
its gravity, it is flatted into an Oval. Quicksilver also which to Glass is more
incongruous then Air (and thereby being put into a Glass-pipe, will not
adhere to it, but by the more congruous air will be forced to have a very
protuberant surface, and to rise higher in a greater then a lesser Pipe) this
Quicksilver to clean Metal, especially to Gold, Silver, Tin, Lead, &c. Iron
excepted, is more congruous then Air, and will not only stick to it, but have
a concave Surface like water, and rise higher in a less, then in a greater
Pipe.
In all these Examples it is evident, that there is an extraordinary and
adventitious force, by which the globular Figure of the contained
heterogeneous fluid is altered; neither can it be imagined, how it should
otherwise be of any other Figure then Globular: For being by the
heterogeneous fluid equally protruded every way, whatsoever part is
protuberant, will be thereby deprest. From this cause it is, that in its effects
it does very much resemble a round Spring (such as a Hoop.) For as in a
round Spring there is required an additional pressure against two opposite
sides, to reduce it into an Oval Form, or to force it in between the sides of a
Hole, whose Diameter is less then that of the Spring, there must be a
considerable force or protrusion against the concave or inner side of the
Spring; So to alter this spherical constitution of an included fluid body,
there is required more pressure against opposite sides to reduce it into an
Oval; and, to press it into an Hole less in Diameter then it self, it requires a
greater protrusion against all the other sides, What degrees of force are
requisite to reduce them into longer and longer Ovals, or to press them into
less and less holes, I have not yet experimentally calculated; but thus much
by experiment I find in general, that there is alwayes required a greater

pressure to close them into longer Ovals, or protrude them into smaller
holes. The necessity and reason of this, were it requisite, I could easily
explain: but being not so necessary, and requiring more room and time then
I have for it at present, I shall here omit it; and proceed to shew, that this
may be presently found true, if Experiment be made with a round Spring
(the way of making which trials is obvious enough.) And with the fluid
bodies of Mercury, Air, &c. the way of trying which, will be somewhat
more difficult; and therefore I shall in brief describe it. He therefore that
would try with Air, must first be provided of a Glass-pipe, made of the
shape of that in the fifth Figure, whereof the side AB, represents a straight
Tube of about three foot long, C, represents another part of it, which
consists of a round Bubble; so ordered, that there is left a passage or hole at
the top, into which may be fastened with cement several small Pipes of
determinate cylindrical cavities: as let the hollow of

F. ¼
G. ⅙
H. ⅛
I. be ¹⁄₁₂ of an inch.
K. ¹⁄₁₆
L. ¹⁄₂₄
M. ¹⁄₃₂
&c.——

There may be added as many more, as the Experimenter shall think fit,
with holes continually decreasing by known quantities, so far as his senses
are able to help him; I say, so far, because there may be made Pipes so
small that it will be impossible to perceive the perforation with ones naked
eye, though by the help of a Microscope, it may easily enough be perceived:
Nay, I have made a Pipe perforated from end to end, so small, that with my
naked eye I could very hardly see the body of it, insomuch that I have been
able to knit it up into a knot without breaking: And more accurately
examining one with my Microscope, I found it not so big as a sixteenth part
of one of the smaller hairs of my head which was of the smaller and finer
sort of hair, so that sixteen of these Pipes bound faggot-wise together,
would but have equalized one single hair; how small therefore must its

perforation be? It appearing to me through the Microscope to be a
proportionably thick-sided Pipe.
To proceed then, for the trial of the Experiment, the Experimenter must
place the Tube AB, perpendicular, and fill the Pipe F (cemented into the
hole E) with water, but leave the bubble C full of Air, and then gently
pouring in water into the Pipe AB, he must observe diligently how high the
water will rise in it before it protrude the bubble of Air C, through the
narrow passage of F, and denote exactly the height of the Cylinder of water,
then cementing in a second Pipe as G, and filling it with water; he may
proceed as with the former, denoting likewise the height of the Cylinder of
water, able to protrude the bubble C through the passage of G, the like may
he do with the next Pipe, and the next, &c. as far as he is able: then
comparing the several heights of the Cylinders, with the several holes
through which each Cylinder did force the air (having due regard to the
Cylinders of water in the small Tubes) it will be very easie to determine,
what force is requisite to press the Air into such and such a hole, or (to
apply it to our present experiment) how much of the pressure of the Air is
taken off by its ingress into smaller and smaller holes. From the application
of which to the entring of the Air into the bigger hole of the Vessel, and into
the smaller hole of the Pipe, we shall clearly find, that there is a greater
pressure of the air upon the water in the Vessel or greater pipe, then there is
upon that in the lesser pipe: For since the pressure of the air every way is
found to be equal, that is, as much as is able to press up and sustain a
Cylinder of Quicksilver of two foot and a half high, or thereabouts; And
since of this pressure so many more degrees are required to force the Air
into a smaller then into a greater hole that is full of a more congruous fluid.
And lastly, since those degrees that are requisite to press it in, are thereby
taken off from the Air within, and the Air within left with so many degrees
of pressure less then the Air without; it will follow, that the Air in the less
Tube or pipe, will have less pressure against the superficies of the water
therein, then the Air in the bigger: which was the minor Proposition to be
proved.
The Conclusion therefore will necessarily follow, viz. That this unequal
pressure of the Air caused by its ingress into unequal holes, is a cause
sufficient to produce this effect, without the help of any other concurrent;

and therefore is probably the principal (if not the only) cause of these
Phænomena.
This therefore being thus explained, there will be divers Phænomena
explicable thereby, as, the rising of Liquors in a Filtre, the rising of Spirit of
Wine, Oyl, melted Tallow, &c. in the Week of a Lamp, (though made of
small Wire, Threeds of Asbestus, Strings of Glass, or the like) the rising of
Liquors in a Spunge, piece of Bread, Sand, &c. perhaps also the ascending
of the Sap in Trees and Plants, through their small, and some of them
imperceptible pores, (of which I have said more, on another occasion) at
least the passing of it out of the earth into their roots. And indeed upon the
consideration of this Principle, multitudes of other uses of it occurr’d to me,
which I have not yet so well examined and digested as to propound for
Axioms, but only as Queries and Conjectures which may serve as hints
toward some further discoveries.
As first, Upon the consideration of the congruity and incongruity of
Bodies, as to touch, I found also the like congruity and incongruity (if I may
so speak) as to the Transmitting of the Rates of Light: For as in this regard,
water (not now to mention other Liquors) seems nearer of affinity to Glass
then Air, and Air then Quicksilver: whence an oblique Ray out of Glass,
will pass into water with very little refraction from the perpendicular, but
none out of Glass into Air, excepting a direct, will pass without a very great
refraction from the perpendicular, nay any oblique Ray under thirty degrees,
will not be admitted into the Air at all. And Quicksilver will neither admit
oblique or direct, but reflects all; seeming, as to the transmitting of the
Raies of Light, to be of a quite differing constitution, from that of Air,
Water, Glass, &c. and to resemble most those opacous and strong reflecting
bodies of Metals: So also as to the property of cohesion or congruity, Water
seems to keep the same order, being more congruous to Glass then Air, and
Air then Quicksilver.
A Second thing (which was hinted to me, by the consideration of the
included fluids globular form, caused by the protrusion of the ambient
heterogeneous fluid) was, whether the Phænomena of gravity might not by
this means be explained, by supposing the Globe of Earth, Water, and Air to
be included with a fluid, heterogeneous to all and each of them, so subtil, as
not only to be every where interspersed through the Air, (or rather the air

through it) but to pervade the bodies of Glass, and even the closest Metals,
by which means it may endeavour to detrude all earthly bodies as far from
it as it can; and partly thereby, and partly by other of its properties may
move them towards the Center of the Earth. Now that there is some such
fluid, I could produce many Experiments and Reasons, that do seem to
prove it: But because it would ask some time and room to set them down
and explain them, and to consider and answer all the Objections (many
whereof I foresee) that may be alledged against it; I shall at present proceed
to other Queries, contenting my self to have here only given a hint of what I
may say more elswhere.
A Third Query then was, Whether the heterogeneity of the ambient fluid
may not be accounted a secondary cause of the roundness or globular form
of the greater bodies of the world, such as are those of the Sun, Stars, and
Planets, the substance of each of which seems altogether heterogeneous to
the circumambient fluid æther? And of this I shall say more in the
Observation of the Moon.
A Fourth was, Whether the globular form of the smaller parcels of matter
here upon the Earth, as that of Fruits, Pebbles, or Flints, &c. (which seem
to have been a Liquor at first) may not be caused by the heterogeneous
ambient fluid. For thus we see that melted Glass will be naturally formed
into a round Figure; so likewise any small Parcel of any fusible body, if it
be perfectly enclosed by the Air, will be driven into a globular Form; and,
when cold, will be found a solid Ball. This is plainly enough manifested to
us by their way of making shot with the drops of Lead; which being a very
pretty curiosity, and known but to a very few, and having the liberty of
publishing it granted me, by that Eminent Virtuoso Sir Robert Moray, who
brought in this Account of it to the Royal Society, I have here transcribed
and inserted.

To make small shot of different sizes; Communicated by his
Highness P.R.

Take Lead out of the Pig what quantity you please, melt it down, stir and
clear it with an iron Ladle, gathering together the blackish parts that swim
at top like scum, and when you see the colour of the clear Lead to be

greenish, but no sooner, strew upon it Auripigmentum powdered according
to the quantity of Lead, about as much as will lye upon a half Crown piece
will serve for eighteen or twenty pound weight of some sorts of Lead; others
will require more, or less. After the Auripigmentum is put in, stir the Lead
well, and the Auripigmentum will flame: when the flame is over, take out
some of the Lead in a Ladle having a lip or notch in the brim for convenient
pouring out of the Lead, and being well warmed amongst the melted Lead,
and with a stick make some single drops of Lead trickle out of the Ladle
into water in a Glass, which if they fall to be round and without tails, there
is Auripigmentum enough put in, and the temper of the heat is right,
otherwise put in more. Then lay two bars of Iron (or some more proper
Iron-tool made on purpose) upon a Pail of water, and place upon them a
round Plate of Copper, of the size and figure of an ordinary large Pewter or
Silver Trencher, the hollow whereof is to be about three inches over, the
bottom lower then the brims about half an inch, pierced with thirty, forty, or
more small holes; the smaller the holes are, the smaller the shot will be;
and the brim is to be thicker then the bottom, to conserve the heat the better.
The bottom of the Trencher being some four inches distant from the water
in the Pail, lay upon it some burning Coles, to keep the Lead melted upon it.
Then with the hot Ladle take Lead off the Pot where it stands melted, and
pour it softly upon the burning Coles over the bottom of the Trencher, and it
will immediately run through the holes into the water in small round drops.
Thus pour on new Lead still as fast as it runs through the Trencher till all
be done; blowing now and then the Coles with hand-Bellows, when the
Lead in the Trencher cools so as to stop from running.
Whilst one pours on the Lead, another must, with another Ladle, thrusted
four or five inches under water in the Pail, catch from time to time some of
the shot, as it drops down, to see the size of it, and whether there be any
faults in it. The greatest care is to keep the Lead upon the Trencher in the
right degree of heat; if it be too cool, it will not run through the Trencher,
though it stand melted upon it; and this is to be helped by blowing the Coals
a little, or pouring on new Lead that is hotter: but the cooler the Lead, the
larger the Shot; and the hotter, the smaller; when it is too hot, the drops will
crack and fly; then you must stop pouring on new Lead, and let it cool; and
so long as you observe the right temper of the heat, the Lead will constantly

drop into very round Shot, without so much as one with a tail in many
pounds.
When all is done, take your Shot out of the Pail of water, and put it in a
Frying-pan over the fire to dry them, which must be done warily, still
shaking them that they melt not; and when they are dry you may separate
the small from the great, in Pearl Sives made of Copper or Lattin let into
one another, into as many sizes at you please. But if you would have your
Shot larger then the Trencher makes them, you may do it with a Stick,
making them trickle out of the Ladle, as hath been said.
If the Trencher be but toucht a very little when the Lead stops from going
through it, and be not too cool, it will drop again, but it is better not to
touch it at all. At the melting of the Lead take care that there be no kind of
Oyl, Grease, or the like, upon the Pots, or Ladles, or Trencher.
The Chief cause of this Globular Figure of the Shot, seems to be the
Auripigmentum; for, as soon as it is put in among the melted Lead, it loses
its shining brightness, contracting instantly a grayish film or skin upon it,
when you scum it to make it clean with the Ladle. So that when the Air
comes at the falling drop of the melted Lead, that skin constricts them every
where equally: but upon what account, and whether this be the true cause,
is left to further disquisition.
Much after this same manner, when the Air is exceeding cold through
which it passes; do we find the drops of Rain, falling from the Clouds,
congealed into round Hail-stones by the freezing Ambient.
To which may be added this other known Experiment, That if you gently
let fall a drop of water upon small sand or dust, you shall find, as it were,
an artificial round stone quickly generated. I cannot upon this occasion omit
the mentioning of the strange kind of Grain, which I have observed in a
stone brought from Kettering in Northamptonshire, and therefore called by
Masons Kettering-Stone, of which see the Description. Which brings into
my mind what I long since observed in the fiery Sparks that are struck out
of a Steel. For having a great desire to see what was left behind, after the
Spark was gone out, I purposely struck fire over a very white piece of
Paper, and observing diligently where some conspicuous sparks went out, I
found a very little black spot no bigger then the point of a Pin, which

through a Microscope appeared to be a perfectly round Ball, looking much
like a polisht ball of Steel, insomuch that I was able to see the Image of the
window reflected from it. I cannot here stay (having done it more fully in
another place) to examine the particular Reasons of it, but shall only hint,
that I imagine it to be some small parcel of the Steel, which by the violence
of the motion of the stroke (most of which seems to be imprest upon those
small parcels) is made so glowing hot, that it is melted into a Vitrum, which
by the ambient Air is thrust into the form of a Ball.
A Fifth thing which I thought worth Examination was, Whether the
motion of all kind of Springs, might not be reduced to the Principle
whereby the included heterogeneous fluid seems to be moved; or to that
whereby two Solids, as Marbles, or the like, are thrust and kept together by
the ambient fluid.
A Sixth thing was, Whether the Rising and Ebullition of the Water out of
Springs and Fountains (which lie much higher from the Center of the Earth
then the Superficies of the Sea, from whence it seems to be derived) may
not be explicated by the rising of Water in a smaller Pipe: For the Sea-water
being strained through the Pores or Crannies of the Earth, is, as it were,
included in little Pipes, where the pressure of the Air has not so great a
power to resist its rising: But examining this way, and finding in it several
difficulties almost irremovable, I thought upon a way that would much
more naturally and conceivably explain it, which was by this following
Experiment: I took a Glass-Tube, of the form of that described in the sixth
Figure, and chusing two heterogeneous fluids, such as Water and Oyl, I
poured in as much Water as filled up the Pipes as high as AB, then putting
in some Oyl into the Tube AC, I deprest the superficies A of the Water to F,
and B I raised to G, which was not so high perpendicularly as the
superficies of the Oyl F, by the space FI, wherefore the proportion of the
gravity of these two Liquors was as GH to FE.
This Experiment I tried with several other Liquors, and particularly with
fresh Water and Salt (which I made by dissolving Salt in warm Water)
which two though they are nothing heterogeneous, yet before they would
perfectly mix one with another, I made trial of the Experiment: Nay, letting
the Tube wherein I tried the Experiment remain for many dayes, I observed
them not to mix; but the superficies of the fresh was rather more then less

elevated above that of the Salt. Now the proportion of the gravity of Sea-
water, to that of River-water, according to Stevinus and Varenius, and as I
have since found pretty true by making trial my self, is as 46. to 45. that is,
46. Ounces of the salt Water will take up no more room then 45. of the
fresh. Or reciprocally 45 pints of salt-water weigh as much as 46 of fresh.
But I found the proportion of Brine to fresh Water to be near 13 to 12:
Supposing therefore GHM to represent the Sea, and FI the height of the
Mountain above the Superficies of the Sea, FM a Cavern in the Earth,
beginning at the bottom of the Sea, and terminated at the top of the
Mountain, LM the Sand at the bottom, through which the Water is as it were
strained, so as that the fresher parts are only permitted to transude, and the
saline kept back; if therefore the proportion of G M to FM be as 45 to 46,
then may the Cylinder of Salt-water GM make the Cylinder of Fresh-water
to rise as high as E, and to run over at N. I cannot here stand to examine or
confute their Opinion, who make the depth of the Sea, below its
Superficies, to be no more perpendicularly measured then the height of the
Mountains above it: ’Tis enough for me to say, there is no one of those that
have asserted it, have experimentally known the perpendicular of either; nor
shall I here determine, whether there may not be many other causes of the
separation of the fresh water from the salt, as perhaps some parts of the
Earth through which it is to pass, may contain a Salt, that mixing and
uniting with the Sea-salt, may precipitate it; much after the same manner as
the Alcalizate and Acid Salts mix and precipitate each other in the
preparation of Tartarum Vitriolatum. I know not also whether the exceeding
cold (that must necessarily be) at the bottom of the Water, may not help
towards this separation, for we find, that warm Water is able to dissolve and
contain more Salt, then the same cold; insomuch that Brines strongly
impregnated by heat, if let cool, do suffer much of their Salt to subside and
crystallize about the bottom and sides. I know not also whether the
exceeding pressure of the parts of the Water one against another, may not
keep the Salt from descending to the very bottom, as finding little or no
room to insert it self between those parts, protruded so violently together, or
else squeeze it upwards into the superiour parts of the Sea, where it may
more easily obtain room for it self, amongst the parts of the Water, by
reason that there is more heat and less pressure. To this Opinion I was
somewhat the more induced by the relations I have met with in

Geographical Writers, of drawing fresh Water from the bottom of the Sea,
which is salt above. I cannot now stand to examine, whether this natural
perpetual motion may not artificially be imitated: Nor can I stand to answer
the Objections which may be made against this my Supposition: As, First,
How it comes to pass, that there are sometimes salt Springs much higher
then the Superficies of the Water? And, Secondly, Why Springs do not run
faster and slower, according to the varying height made of the Cylinder of
Sea-water, by the ebbing and flowing of the Sea?
As to the First, In short, I say, the fresh Water may receive again a saline
Tincture near the Superficies of the Earth, by passing through some salt
Mines, or else many of the saline parts of the Sea may be kept back, though
not all.
And as to the Second, The same Spring may be fed and supplyed by
divers Caverns, coming from very far distant parts of the Sea, so as that it
may in one place be high, in another low water; and so by that means the
Spring may be equally supply’d at all times. Or else the Cavern may be so
straight and narrow, that the water not having so ready and free passage
through it, cannot upon so short and quick mutations of pressure, be able to
produce any sensible effect at such a distance. Besides that, to confirm this
hypothesis, there are many Examples found in Natural Historians, of
Springs that do ebb and flow like the Sea: As particularly, those recorded by
the Learned Camden, and after him by Speed, to be found in this Island:
One of which, they relate to be on the Top of a Mountain, by the small
Village Kilken in Flintshire, Maris æmulus qui statis temporibus suas
evomit & resorbet Aquas; Which at certain times riseth and falleth after the
manner of the Sea. A Second in Caermardenshire, near Caermarden, at a
place called Cantred Bichan; Qui (ut scribit Giraldus) naturali die bis undis
deficiens, & toties exuberans, marinas imitatur instabilitates; That twice in
four and twenty hours ebbing and flowing; resembleth the unstable motions
of the Sea. The Phænomena of which two may be easily made out, by
supposing the Cavern, by which they are fed, to arise from the bottom of
the next Sea. A Third, is a Well upon the River Ogmore in Glamorganshire,
and near unto Newton, of which Camden relates himself to be certified, by a
Letter from a Learned Friend of his that observed it, Fons abest hinc, &c.
The Letter is a little too long to be inserted, but the substance is this; That
this Well ebbs and flows quite contrary to the flowing and ebbing of the Sea

in those parts: for ’tis almost empty at Full Sea, but full at Low water. This
may happen from the Channel by which it is supplied, which may come
from the bottom of a Sea very remote from those parts, and where the Tides
are much differing from those of the approximate shores. A Fourth, lies in
Westmorland, near the River Leder; Qui instar Euripi sæpius in die
reciprocantibus undis fluit & refluit, which ebbs and flows many times a
day. This may proceed from its being supplyed from many Channels,
coming from several parts of the Sea, lying sufficiently distant asunder to
have the times of High water differing enough one from the other; so as that
whensoever it shall be High water over any of those places, where these
Channels begin, it shall likewise be so in the Well; but this is but a
supposition.
A Seventh Query was, Whether the dissolution or mixing of several
bodies, whether fluid or solid, with saline or other Liquors, might not partly
be attributed to this Principle of the congruity of those bodies and their
dissolvents? As of Salt in Water, Metals in several Menstruums, Unctuous
Gums in Oyls, the mixing of Wine and Water, &c. And whether
precipitation be not partly made from the same Principle of Incongruity? I
say partly, because there are in some Dissolutions, some other Causes
concurrent.
I shall lastly make a much more seemingly strange and unlikely Query;
and that is, Whether this Principle, well examined and explained, may not
be found a coefficient in the most considerable Operations of Nature? As in
those of Heat, and Light, and consequently of Rarefaction and
Condensation, Hardness, and Fluidness, Perspicuity and Opacousness,
Refractions and Colours. &c. Nay, I know not whether there may be many
things done in Nature, in which this may not (be said to) have a Finger?
This I have in some other passages of this Treatise further enquired into and
shewn, that as well Light as Heat may be caused by corrosion, which is
applicable to congruity, and consequently all the rest will be but
subsequents: In the mean time I would not willingly be guilty of that Error,
which the thrice Noble and Learned Verulam justly takes notice of, as such,
and calls Philosophiæ Genus Empiricum, quod in paucorum
Experimentorum Angustiis & Obscuritate fundatum est. For I neither
conclude from one single Experiment, nor are the Experiments I make use
of all made upon one Subject: Nor wrest I any Experiment to make it

quadrare with any preconceiv’d Notion. But on the contrary, I endeavour to
be conversant in divers kinds of Experiments, and all and every one of
those Trials, I make the Standards or Touchstones, by which I try all my
former Notions, whether they hold out in weight, and measure, and touch,
&c. For as that Body is no other then a Counterfeit Gold, which wants any
one of the Proprieties of Gold, (such as are the Malleableness, Weight,
Colour, Fixtness in the Fire, Indissolubleness in Aqua fortis, and the like)
though it has all the other; so will all those Notions be found to be false and
deceitful, that will not undergo all the Trials and Tests made of them by
Experiments. And therefore such as will not come up to the desired Apex of
Perfection, I rather wholly reject and take new, then by piecing and
patching, endeavour to retain the old, as knowing such things at best to be
but lame and imperfect. And this course I learned from Nature; whom we
find neglectful of the old Body, and suffering its Decaies and Infirmities to
remain without repair, and altogether sollicitous and careful of perpetuating
the Species by new Individuals. And it is certainly the most likely way to
erect a glorious Structure and Temple to Nature, such as she will be found
(by any zealous Votary) to reside in; to begin to build a new upon a sure
Foundation of Experiments.
But to digress no further from the consideration of the Phænomena, more
immediately explicable by this Experiment, we shall proceed to shew, That,
as to the rising of Water in a Filtre, the reason of it will be manifest to him,
that does take notice, that a Filtre is constituted of a great number of small
long solid bodies, which lie so close together, that the Air in its getting in
between them, doth lose of its pressure that it has against the Fluid without
them, by which means the Water or Liquor not finding so strong a
resistance between them as is able to counter-ballance the pressure on its
superficies without, is raised upward, till it meet with a pressure of the Air
which is able to hinder it. And as to the Rising of Oyl, melted Tallow, Spirit
of Wine, &c. in the Week of a Candle or Lamp, it is evident, that it differs in
nothing from the former, save only in this, that in a Filtre the Liquor
descends and runs away by another part; and in the Week the Liquor is
dispersed and carried away by the Flame; something there is ascribable to
the Heat, for that it may rarifie the more volatil and spirituous parts of those
combustible Liquors, and so being made lighter then the Air, it may be
protruded upwards by that more ponderous fluid body in the Form of

Vapours; but this can be ascribed to the ascension of but a very little, and
most likely of that only which ascends without the Week. As for the Rising
of it in a Spunge, Bread, Cotton, &c. above the superficies of the subjacent
Liquor, what has been said about the Filtre (if considered) will easily
suggest a reason, considering that all these bodies abound with small holes
or pores.
From this same Principle also (viz. the unequal pressure of the Air
against the unequal superficies of the water) proceeds the cause of the
accession or incursion of any floating body against the sides of the
containing Vessel; or the appropinquation of two floating bodies, as
Bubbles, Corks, Sticks, Straws, &c. one towards another. As for instance,
Take a Glass jar, such as AB in the seventh Figure, and filling it pretty near
the top with water, throw into it a small round piece of Cork, as C, and
plunge it all over in water, that it be wet, so as that the water may rise up by
the sides of it, then placing it any where upon the superficies, about an inch,
or one inch and a quarter from any side, and you shall perceive it by
degrees to make perpendicularly toward the nearest part of the side, and the
nearer it approaches, the faster to be moved, the reason of which
Phænomenon will be found no other then this, that the Air has a greater
pressure against the middle of the superficies, then it has against those parts
that approach nearer, and are contiguous to the sides. Now that the pressure
is greater, may (as I shewed before in the explication of the third Figure) be
evinced from the flatting of the water in the middle, which arises from the
gravity of the under fluid: for since, as I shewed before, if there were no
gravity in the under fluid, or that it were equal to that of the upper, the
terminating Surface would be Spherical, and since it is the additional
pressure of the gravity of water that makes it so flat, it follows, that the
pressure upon the middle must be greater then towards the sides. Hence the
Ball having a stronger pressure against that side of it which respects the
middle of the superficies, then against that which respects the approximate
side, must necessarily move towards that part, from whence it finds least
resistance, and so be accelerated, as the resistance decrease. Hence the
more the water is raised under that part of its way it is passing above the
middle, the faster it is moved: And therefore you will find it to move faster
in E then in D, and in D then in C. Neither could I find the floating
substance to be moved at all, until it were placed upon some part of the

Superficies that was sensibly elevated above the height of the middle part.
Now that this may be the true cause, you may try with a blown Bladder, and
an exactly round Ball upon a very smooth side of some pliable body, as
Horn or Quicksilver. For if the Ball be placed under a part of the Bladder
which is upon one side of the middle of its pressure, and you press strongly
against the Bladder, you shall find the Ball moved from the middle towards
the sides.
Having therefore shewn the reason of the motion of any float towards the
sides, the reason of the incursion of any two floating bodies will easily
appear: For the rising of the water against the sides of either of them, is an
Argument sufficient, to shew the pressure of the Air to be there less, then it
is further from it, where it is not so much elevated; and therefore the reason
of the motion of the other toward it, will be the same as towards the side of
the Glass, only here from the same reason, they are mutually moved toward
each other, whereas the side of the Glass in the former remains fixt. If also
you gently fill the Jar so full with water, that the water is protuberant above
the sides, the same piece of Cork that before did hasten towards the sides,
does now fly from it as fast towards the middle of the Superficies; the
reason of which will be found no other then this, that the pressure of the Air
is stronger against the sides of the Superficies G and H, then against the
middle I; for since, as I shewed before, the Principle of congruity would
make the terminating Surface Spherical, and that the flatting of the Surface
in the middle is from the abatement of the waters pressure outwards, by the
contrary indeavour of its gravity; it follows that the pressure in the middle
must be less then on the sides; and therefore the consecution will be the
same as in the former. It is very odd to one that considers not the reason of
it, to see two floating bodies of wood to approach each other, as though they
were indued with some magnetical vigour; which brings into my mind what
I formerly tried with a piece of Cork or such like body, which I so ordered,
that by putting a little stick into the same water, one part of the said Cork
would approach and make toward the stick, whereas another would discede
and fly away, nay it would have a kind of verticity, so as that if the Æquator
(as I may so speak) of the Cork were placed towards the stick, if let alone, it
would instantly turn its appropriate Pole toward it, and then run a-tilt at it:
and this was done only by taking a dry Cork, and wetting one side of it with
one small stroak; for by this means gently putting it upon the water, it

would depress the superficies on every side of it that was dry, and therefore
the greatest pressure of the Air, being near those sides, caused it either to
chase away, or else to fly off from any other floating body, whereas that
side only, against which the water ascended, was thereby able to attract.
It remains only, that I should determine how high the Water or other
Liquor may by this means be raised in a smaller Pipe above the Superficies
of that without it, and at what height it may be sustained: But to determine
this, will be exceeding difficult, unless I could certainly know how much of
the Airs pressure is taken off by the smalness of such and such a Pipe, and
whether it may be wholly taken off, that is, whether there can be a hole or
pore so small, into which Air could not at all enter, though water might with
its whole force, for were there such, ’tis manifest, that the water might rise
in it to some five or six and thirty English Foot high. I know not whether
the capillary Pipes in the bodies of small Trees, which we call their
Microscopical pores, may not be such; and whether the congruity of the
sides of the Pore may not yet draw the juyce even higher then the Air was
able by its bare pressure to raise it: For, Congruity is a principle that not
only unites and holds a body joyned to it, but, which is more, attracts and
draws a body that is very near it, and holds it above its usual height.
And this is obvious even in a drop of water suspended under any Similar
or Congruous body: For, besides the ambient pressure that helps to keep it
sustein’d, there is the Congruity of the bodies that are contiguous. This is
yet more evident in Tenacious and Glutinous bodies; such as Gummous
Liquors, Syrups, Pitch, and Rosin melted, &c. Tar, Turpentine, Balsom,
Birdlime, &c. for there it is evident, that the Parts of the tenacious body, as I
may so call it, do stick and adhere so closely together, that though drawn
out into long and very slender Cylinders, yet they will not easily relinquish
one another; and this, though the bodies be aliquatenus fluid, and in motion
by one another, which, to such as consider a fluid body only as its parts are
in a confused irregular motion, without taking in also the congruity of the
parts one among another, and incongruity to some other bodies, does appear
not a little strange. So that besides the incongruity of the ambient fluid to it,
we are to consider also the congruity of the parts of the contein’d fluid one
with another.

And this Congruity (that I may here a little further explain it) is both a
Tenacious and an Attractive power; for the Congruity, in the Vibrative
motions, may be the cause of all kind of attraction, not only Electrical, but
Magnetical also, and therefore it may be also of Tenacity and
Glutinousness. For, from a perfect congruity of the motions of two distant
bodies, the intermediate fluid particles are separated and droven away from
between them, and thereby those congruous bodies are, by the
incompassing mediums, compell’d and forced neerer together; wherefore
that attractiveness must needs be stronger, when, by an immediate contact,
they are forc’d to be exactly the same: As I shew more at large in my
Theory of the Magnet. And this hints to me the reason of the suspension of
the Mercury many inches, nay many feet, above the usual station of 30
inches. For the parts of Quick-Silver, being so very similar and congruous
to each other, if once united, will not easily suffer a divulsion: And the parts
of water, that were any wayes heterogeneous, being by exantlation or
rarefaction exhausted, the remaining parts being also very similar, will not
easily part neither. And the parts of the Glass being solid, are more
difficultly disjoyn’d; and the water, being somewhat similar to both, is, as it
were, a medium to unite both the Glass and the Mercury together. So that
all three being united, and not very dissimilar, by means of this contact, if
care be taken that the Tube in erecting be not shogged, the Quicksilver will
remain suspended, notwithstanding its contrary indeavour of Gravity, a
great height above its ordinary Station; but if this immediate Contact be
removed, either by a meer separation of them one from another by the force
of a shog, whereby the other becomes imbodied between them, and licks up
from the surface some agil parts, and so hurling them makes them air, or
else by some small heterogeneous agil part of the Water, or Air, or
Quicksilver, which appears like a bubble, and by its jumbling to and fro
there is made way for the heterogeneous Æther to obtrude it self between
the Glass and either of the other Fluids, the Gravity of Mercury precipitates
it downward with very great violence; and if the Vessel that holds the
restagnating Mercury be convenient, the Mercury will for a time vibrate to
and fro with very large reciprocations, and at last will remain kept up by the
pressure of the external Air at the height of neer thirty inches. And whereas
it may be objected, that it cannot be, that the meer imbodying of the Æther
between these bodies can be the cause, since the Æther having a free
passage alwayes, both through the Pores of the Glass, and through those of

the Fluids, there is no reason why it should not make a separation at all
times whilst it remains suspended, as when it is violently disjoyned by a
shog. To this I answer, That though the Æther passes between the Particles,
that is, through the Pores of bodies, so as that any chasm or separation
being made, it has infinite passages to admit its entry into it, yet such is the
tenacity or attractive virtue of Congruity, that till it be overcome by the
meer strength of Gravity, or by a shog assisting that Conatus of Gravity, or
by an agil Particle, that is like a leaver agitated by the Æther; and thereby
the parts of the congruous substances are separated so far asunder, that the
strength of congruity is so far weakened, as not to be able to reunite them,
the parts to be taken hold of being removed out of the attractive Sphere, as I
may so speak, of the congruity; such, I say, is the tenacity of congruity, that
it retains and holds the almost contiguous Particles of the Fluid, and suffers
them not to be separated, till by meer force that attractive or retentive
faculty be overcome: But the separation being once made beyond the
Sphere of the attractive activity of congruity, that virtue becomes of no
effect at all, but the Mercury freely falls downwards till it meet with a
resistance from the pressure of the ambient Air, able to resist its gravity, and
keep it forced up in the Pipe to the height of about thirty inches.
Thus have I gently raised a Steel pendulum by a Loadstone to a great
Angle, till by the shaking of my hand I have chanced to make a separation
between them, which is no sooner made, but as if the Loadstone had
retained no attractive virtue, the Pendulum moves freely from it towards the
other side. So vast a difference is there between the attractive virtue of the
Magnet when it acts upon a contiguous and upon a disjoyned body: and
much more must there be between the attractive virtues of congruity upon a
contiguous and disjoyned body; and in truth the attractive virtue is so little
upon a body disjoyned, that though I have with a Microscope observed very
diligently, whether there were any extraordinary protuberance on the side of
a drop of water that was exceeding neer to the end of a green stick, but did
not touch it, I could not perceive the least; though I found, that as soon as
ever it toucht it the whole drop would presently unite it self with it; so that
it seems an absolute contact is requisite to the exercising of the tenacious
faculty of congruity.

Observ. VII. Of some Phænomena of Glass drops.
These Glass Drops are small parcels of coarse green Glass taken out of
the Pots that contain the Metal (as they call it) in fusion, upon the end of an
Iron Pipe; and being exceeding hot, and thereby of a kind of sluggish fluid
Consistence, are suffered to drop from thence into a Bucket of cold Water,
and in it to lye till they be grown sensibly cold.
Some of these I broke in the open air, by snapping off a little of the small
stem with my fingers, others by crushing it with a small pair of Plyers;
which I had no sooner done, then the whole bulk of the drop flew violently,
with a very brisk noise, into multitudes of small pieces, some of which were
as small as dust, though in some there were remaining pieces pretty large,
without any flaw at all, and others very much flaw’d, which by rubbing
between ones fingers was easily reduced to dust; these dispersed every way
so violently, that some of them pierced my skin. I could not find, either with
my naked Eye, or a Microscope, that any of the broken pieces were of a
regular figure, nor any one like another, but for the most part those that
flaw’d off in large pieces were prettily branched.
The ends of others of these drops I nipt off whilst all the bodies and ends
of them lay buried under the water, which, like the former, flew all to pieces
with as brisk a noise, and as strong a motion.
Others of these I tried to break, by grinding away the blunt end, and
though I took a seemingly good one, and had ground away neer two thirds
of the Ball, yet would it not fly to pieces, but now and then some small
rings of it would snap and fly off, not without a brisk noise and quick
motion, leaving the Surface of the drop whence it flew very prettily
branched or creased, which was easily discoverable by the Microscope.
This drop, after I had thus ground it, without at all impairing the remnant
that was not ground away, I caused to fly immediately all into sand upon the
nipping off the very tip of its slender end.
Another of these drops I began to grind away at the smaller end, but had
not worn away on the stone above a quarter of an inch before the whole

drop flew with a brisk crack into sand or small dust; nor would it have held
so long, had there not been a little flaw in the piece that I ground away, as I
afterwards found.
Several others of these drops I covered over with a thin but very tuff skin
of Icthyocolla, which being very tough and very transparent, was the most
convenient substance for these tryals that I could imagine, having dipt, I
say, several of these drops in this transparent Glue whilst hot, and suffering
them to hang by a string tied about the end of them till they were cold, and
the skin pretty tough; then wrapping all the body of the drop (leaving out
only the very tip) in fine supple Kids-leather very closely, I nipped off the
small top, and found, as I expected, that notwithstanding this skin of Glue,
and the close wrapping up in Leather, upon the breaking of the top, the drop
gave a crack like the rest, and gave my hand a pretty brisk impulse: but yet
the skin and leather was so strong as to keep the parts from flying out of
their former posture; and, the skin being transparent, I found that the drop
retained exactly its former figure and polish, but was grown perfectly
opacous and all over flaw’d, all those flaws lying in the manner of rings,
from the bottom or blunt end, to the very top or small point. And by several
examinations with a Microscope, of several thus broken, I found the flaws,
both within the body of the drop, and on the outward surface, to lye much in
this order.
Schem. 4.
Fig. X.

Let AB in the Figure X of the fourth Scheme represent the drop cased
over with Icthyocolla or Isinglass, (by being ordered as is before
prescribed) crazed or flawed into pieces, but by the skin or case kept in its
former figure, and each of its flawed parts preserved exactly in its due
posture; the outward appearance of it somewhat plainly to the naked eye,
but much more conspicuous if viewed with a small lens appeared much
after this shape. That is, the blunt end B for a pretty breadth, namely, as far
as the Ring CCC seemed irregularly flawed with divers clefts, which all
seemed to tend towards the Center of it, being, as I afterwards found, and
shall anon shew in the description of the figure Y, the Basis, as it were, of a
Cone, which was terminated a little above the middle of the drop, all the
rest of the Surface from CCC to A was flawed with an infinite number of
small and parallel Rings, which as they were for the most part very round,

so were they very thick and close together, but were not so exactly flaw’d as
to make a perfect Ring, but each circular part was by irregular cracks
flawed likewise into multitudes of irregular flakes or tiles; and this order
was observed likewise the whole length of the neck.
Now though I could not so exactly cut this conical Body through the
Axis, as is represented by the figure Y; yet by anatomizing, as it were, of
several, and taking notice of divers particular circumstances, I was
informed, that could I have artificially divided a flaw’d drop through the
Axis or Center, I should with a Microscope have found it to appear much of
this form, where A signifies the Apex, and B the blunt end, CC the Cone of
the Basis, which is terminated at T the top or end of it, which seems to be
the very middle of the blunt end in which, not only the conical body of the
Basis CC is terminated, but as many of the parts of the drop as reach as high
as DD.
And it seemed to be the head or beginning of a Pith, as it were, or a part
of the body which seemed more spungy then the rest, and much more
irregularly flawed, which from T ascended by EE, though less visible, into
the small neck towards A. The Grain, as it were, of all the flaws, that
proceeds from all the outward Surface ADCCDA, was much the same, as is
represented by the black strokes that meet in the middle DT, DT, DE, DE,
&c.
Nor is this kind of Grain, as I may call it, peculiar to Glass drops thus
quenched; for (not to mention Coperas-stones, and divers other Marchasites
and Minerals, which I have often taken notice of to be in the very same
manner flaked or grained, with a kind of Pith in the middle) I have observed
the same in all manner of cast Iron, especially the coarser sort, such as
Stoves, and Furnaces, and Backs, and Pots are made of: For upon the
breaking of any of those Substances it is obvious to observe, how from the
out-sides towards the middle, there is a kind of Radiation or Grain much
resembling this of the Glass-drop; but this Grain is most conspicuous in
Iron-bullets, if they be broken: the same Phænomena may be produced by
casting regulus of Antimony into a Bullet-mold, as also with Glass of
Antimony, or with almost any such kind of Vitrified substance, either cast
into a cold Mold or poured into Water.

Others of these Drops I heat red hot in the fire, and then suffered them to
cool by degrees. And these I found to have quite lost all their fulminating or
flying quality, as also their hard, brittle and springy texture; and to emerge
of a much softer temper, and much easier to be broken or snapt with ones
finger; but its strong and brittle quality was quite destroyed, and it seemed
much of the same consistence with other green Glass well nealed in the
Oven.
The Figure and bigness of these for the most part was the same with that
of the Figure Z; that is, all the surface of them was very smooth and polisht,
and for the most part round, but very rugged or knobbed about D, and all
the length of the stem was here and there pitted or flatted. About D, which
is at the upper part of the drop under that side of the stem which is concave,
there usually was made some one or more little Hillocks or Prominences.
The drop it self, before it be broken, appears very transparent, and towards
the middle of it, to be very full of small Bubbles, of some kind of aerial
substance, which by the refraction of the outward surface appear much
bigger then really they are; and this may be in good part removed, by
putting the drop under the surface of clear Water, for by that means most
part of the refraction of the convex Surface of the drop is destroyed, and the
bubbles will appear much smaller. And this, by the by, minds me of the
appearing magnitude of the aperture of the iris, or pupil of the eye, which
though it appear, and be therefore judged very large, is yet not above a
quarter of the bigness it appears of, by the lenticular refraction of the
Cornea.
The cause of all which Phænomena I imagine to be no other then this,
That the Parts of the Glass being by the excessive heat of the fire kept off
and separated one from another, and thereby put into a kind of sluggish
fluid Consistence, are suffered to drop off with that heat or agitation
remaining in them, into cold Water; by which means the outsides of the
drop are presently cool’d and crusted, and are thereby made of a loose
texture, because the parts of it have not time to settle themselves leisurely
together, and so to lie very close together: And the innermost parts of the
drop, retaining still much of their former heat and agitations, remain of a
loose texture also, and, according as the cold strikes inwards from the
bottom and sides, are quenched, as it were, and made rigid in that very
posture wherein the cold finds them. For the parts of the crust being already

hardened, will not suffer the parts to shrink any more from the outward
Surface inward; and though it shrink a little by reason of the small parcels
of some Aerial substances dispersed through the matter of the Glass, yet
that is not neer so much as it appears (as I just now hinted;) nor if it were,
would it be sufficient for to consolidate and condense the body of Glass into
a tuff and close texture, after it had been so excessively rarified by the heat
of the glass-Furnace.
But that there may be such an expansion of the aerial substance contained
in those little blebbs or bubbles in the body of the drop, this following
Experiment will make more evident.

Take a small Glass-Cane about a foot long, seal up one end of it
hermetically, then put in a very small bubble of Glass, almost of the shape
of an Essence-viol with the open mouth towards the sealed end, then draw
out the other end of the Pipe very small, and fill the whole Cylinder with
water, then set this Tube by the Fire till the Water begin to boyl, and the Air
in the bubble be in good part rarified and driven out, then by sucking at the
smalling Pipe, more of the Air or vapours in the bubble may be suck’d out,
so that it may sink to the bottom; when it is sunk to the bottom, in the flame
of a Candle, or Lamp, nip up the slender Pipe and let it cool: whereupon it
is obvious to observe, first, that the Water by degrees will subside and
shrink into much less room: Next, that the Air or vapours in the Glass will
expand themselves so, as to buoy up the little Glass: Thirdly, that all about
the inside of the Glass-pipe there will appear an infinite number of small
bubbles, which as the Water grows colder and colder will swell bigger and
bigger, and many of them buoy themselves up and break at the top.
From this Disceding of the heat in Glass drops, that is, by the quenching
or cooling Irradiations propagated from the Surface upwards and inwards,
by the lines CT, CT, DT, DE, &c. the bubbles in the drop have room to
expand themselves a little, and the parts of the Glass contract themselves;
but this operation being too quick for the sluggish parts of the Glass, the
contraction is performed very unequally and irregularly, and thereby the
Particles of the Glass are bent, some one way, and some another, yet so as
that most of them draw towards the Pith or middle TEEE, or rather from
that outward: so that they cannot extricate or unbend themselves, till some

part of TEEE be broken and loosened, for all the parts about that are placed
in the manner of an Arch, and so till their hold at TEEE be loosened they
cannot fly asunder, but uphold, and shelter, and fix each other much like the
stones in a Vault, where each stone does concurre to the stability of the
whole Fabrick, and no one stone can be taken away but the whole Arch
falls. And wheresoever any of those radiating wedges DTD, &c. are
removed, which are the component parts of this Arch, the whole Fabrick
presently falls to pieces; for all the Springs of the several parts are set at
liberty, which immediately extricate themselves and fly asunder every way;
each part by its spring contributing to the darting of it self and some other
contiguous part. But if this drop be heat so hot as that the parts by degrees
can unbend themselves, and be settled and annealed in that posture, and be
then suffered gently to subside and cool; The parts by this nealing losing
their springiness, constitute a drop of a more soft but less brittle texture, and
the parts being not at all under a flexure, though any part of the middle or
Pith TEEE be broken, yet will not the drop at all fly to pieces as before.
This Conjecture of mine I shall indeavour to make out by explaining each
particular Assertion with analogous Experiments: The Assertions are these.

First, That the parts of the Glass, whilst in a fluid Consistence
and hot, are more rarified, or take up more room, then when hard
and cold.
Secondly, That the parts of the drop do suffer a two-fold
contraction.
Thirdly, That the dropping or quenching the glowing metal in
the Water makes it of a hard, springing, and rarified texture.
Fourthly, That there is a flexion or force remaining upon the
parts of the Glass thus quenched, from which they indeavour to
extricate themselves.
Fifthly, That the Fabrick of the drop, that is able to hinder the
parts from extricating themselves, is analogus to that of an Arch.
Sixthly, That the sudden flying asunder of the parts proceeds
from their springiness.

Seventhly, That a gradual heating and cooling does anneal or
reduce the parts of Glass to a texture that is more loose, and
easilier to be broken, but not so brittle.

That the first of these is true may be gathered from this, That Heat is a
property of a body arising from the motion or agitation of its parts; and
therefore whatever body is thereby toucht must necessarily receive some
part of that motion, whereby its parts will be shaken and agitated, and so by
degrees free and extricate themselves from one another, and each part so
moved does by that motion exert a conatus of protruding and displacing all
the adjacent Particles. Thus Air included in a vessel, by being heated will
burst it to pieces. Thus have I broke a Bladder held over the fire in my hand,
with such a violence and noise, that it almost made me deaf for the present,
and much surpassed the noise of a Musket: The like have I done by
throwing into the fire small glass Bubbles hermetically sealed, with a little
drop of Water included in them. Thus Water also, or any other Liquor,
included in a convenient vessel, by being warmed, manifestly expands it
self with a very great violence, so as to break the strongest vessel, if when
heated it be narrowly imprisoned in it. This is very manifest by the Sealed
Thermometers, which I have, by several tryals, at last brought to a great
certainty and tenderness: for I have made some with stems above four foot
long, in which the expanding Liquor would so far vary, as to be very neer
the very top in the heat of Summer, and prety neer the bottom at the coldest
time of the Winter. The Stems I use for them are very thick, straight, and
even Pipes of Glass, with a very small perforation, and both the head and
body I have made on purpose at the Glass-house, of the same metal whereof
the Pipes are drawn: these I can easily in the flame of a Lamp, urged with
the blast of a pair of Bellows, seal and close together, so as to remain very
firm, close and even; by this means I joyn on the body first, and then fill
both it and a part of the stem, proportionate to the length of the stem and the
warmth of the season I fill it in with the best rectified Spirit of Wine highly
ting’d with the lovely colour of Cocheneel, which I deepen the more by
pouring some drops of common Spirit of Urine, which must not be too well
rectified, because it will be apt to make the Liquor to curdle and stick in the
small perforation of the stem. This Liquor I have upon tryal found the most
tender of any spirituous Liquor, and those are much more sensibly affected
with the variations of heat and cold then other more flegmatick and

ponderous Liquors, and as capable of receiving a deep tincture, and keeping
it, as any Liquor whatsoever; and (which makes it yet more acceptable) is
not subject to be frozen by any cold yet known. When I have thus filled it, I
can very easily in the forementioned flame of a Lamp seal and joyn on the
head of it.
Then, for graduating the stem, I fix that for the beginning of my division
where the surface of the liquor in the stem remains when the ball is placed
in common distilled water, that is so cold that it just begins to freeze and
shoot into flakes; and that mark I fix at a convenient place of the stem, to
make it capable of exhibiting very many degrees of cold, below that which
is requisite to freeze water: the rest of my divisions, both above and below
this (which I mark with a [0] or nought) I place according to the Degrees of
Expansion, or Contraction of the Liquor in proportion to the bulk it had
when it indur’d the newly mention’d freezing cold. And this may be very
easily and accurately enough done by this following way; Prepare a
Cylindrical vessel of very thin plate Brass or Silver, ABCD of the figure Z;
the Diameter AB of whose cavity let be about two inches, and the depth BC
the same; let each end be cover’d with a flat and smooth plate of the same
substance, closely soder’d on, and in the midst of the upper cover make a
pretty large hole EF, about the bigness of a fifth part of the Diameter of the
other; into this fasten very well with cement a straight and even Cylindrical
pipe of Glass, EFGH, the Diameter of whose cavity let be exactly one tenth
of the Diameter of the greater Cylinder. Let this pipe be mark’d at GH with
a Diamant, so that G from E may be distant just two inches, or the same
height with that of the cavity of the greater Cylinder, then divide the length
EG exactly into 10 parts, so the capacity of the hollow of each of these
divisions will be ¹⁄₁₀₀₀ part of the capacity of the greater Cylinder. This
vessel being thus prepared, the way of marking and graduating the
Thermometers may be very easily thus performed:
Fill this Cylindrical vessel with the same liquor wherewith the
Thermometers are fill’d, then place both it and the Thermometer you are to
graduate, in water that is ready to be frozen, and bring the surface of the
liquor in the Thermometer to the first marke or [0]; then so proportion the
liquor in the Cylindrical vessel, that the surface of it may just be at the
lower end of the small glass-Cylinder; then very gently and gradually warm
the water in which both the Thermometer and this Cylindrical vessel stand,

and as you perceive the ting’d liquor to rise in both stems, with the point of
a Diamond give several marks on the stem of the Thermometer at those
places, which by comparing the expansion in both Stems, are found to
correspond to the divisions of the cylindrical vessel, and having by this
means marked some few of these divisions on the Stem, it will be very easie
by these to mark all the rest of the Stem, and accordingly to assign to every
division a proper character.
A Thermometer, thus marked and prepared, will be the fittest Instrument
to make a Standard of heat and cold that can be imagined. For being sealed
up, it is not at all subject to variation or wasting, nor is it liable to be
changed by the varying pressure of the Air, which all other kind of
Thermometers that are open to the Air are liable to. But to proceed.
This property of Expansion with Heat, and Contraction with Cold, is not
peculiar to Liquors only, but to all kind of solid Bodies also, especially
Metals, which will more manifestly appear by this Experiment.
Take the Barrel of a Stopcock of Brass, and let the Key, which is well
fitted to it, be riveted into it, so that it may slip, and be easily turned round,
then heat this Cock in the fire, and you will find the Key so swollen, that
you will not be able to turn it round in the Barrel; but if it be suffered to
cool again, as soon as it is cold it will be as movable, and as easie to be
turned as before.
This Quality is also very observable in Lead, Tin, Silver, Antimony, Pitch,
Rosin, Bees-wax, Butter, and the like; all which, if after they be melted you
suffer gently to cool, you shall find the parts of the upper Surface to subside
and fall inwards, losing that plumpness and smoothness it had whilst in
fusion. The like I have also observed in the cooling of Glass of Antimony,
which does very neer approach the nature of Glass,
But because these are all Examples taken from other materials then
Glass, and argue only, that possibly there may be the like property also in
Glass, not that really there is; we shall by three or four Experiments
indeavour to manifest that also.
And the First is an Observation that is very obvious even in these very
drops, to wit, that they are all of them terminated with an unequal or

irregular Surface, especially about the smaller part of the drop, and the
whole length of the stem; as about D, and from thence to A, the whole
Surface, which would have been round if the drop had cool’d leisurely, is,
by being quenched hastily, very irregularly flatted and pitted; which I
suppose proceeds partly from the Waters unequally cooling and pressing the
parts of the drop, and partly from the self-contracting or subsiding quality
of the substance of the Glass: For the vehemency of the heat of the drop
causes such hidden motions and bubbles in the cold Water, that some parts
of the Water bear more forcibly against one part then against another, and
consequently do more suddenly cool those parts to which they are
contiguous.
A Second Argument may be drawn from the Experiment of cutting
Glasses with a hot Iron. For in that Experiment the top of the Iron heats, and
thereby rarifies the parts of the Glass that lie just before the crack, whence
each of those agitated parts indeavouring to expand its self and get elbow-
room, thrusts off all the rest of the contiguous parts, and consequently
promotes the crack that was before begun.
A Third Argument may be drawn from the way of producing a crack in a
sound piece or plate of Glass, which is done two wayes, either First, by
suddenly heating a piece of Glass in one place more then in another. And by
this means chymists usually cut off the necks of Glass-bodies, by two kinds
of Instruments, either by a glowing hot round Iron-Ring, which just
incompasses the place that is to be cut, or else by a Sulphur’d Threed,
which is often wound about the place where the separation is to be made,
and then fired. Or Secondly, A Glass may be cracked by cooling it suddenly
in any place with Water, or the like, after it has been all leisurely and
gradually heated very hot. Both which Phænomena seem manifestly to
proceed from the expansion and contraction of the parts of the Glass, which
is also made more probable by this circumstance which I have observed,
that a piece of common window-glass being heated in the middle very
suddenly with a live Coal or hot Iron, does usually at the first crack fall into
pieces, whereas if the Plate has been gradually heated very hot, and a drop
of cold Water and the like be put on the middle of it, it only flaws it, but
does not break it asunder immediately.

A Fourth Argument may be drawn from this Experiment; Take a Glass-
pipe, and fit into a solid stick of Glass, so as it will but just be moved in it.
Then by degrees heat them whilst they are one within another, and they will
grow stiffer, but when they are again cold, they will be as easie to be turned
as before. This Expansion of Glass is more manifest in this Experiment.
Take a stick of Glass of a considerable length, and fit it so between the
two ends or screws of a Lath, that it may but just easily turn, and that the
very ends of it may be just toucht and susteined thereby; then applying the
flame of the Candle to the middle of it, and heating it hot, you will presently
find the Glass to stick very fast on those points, and not without much
difficulty to be convertible on them, before that by removing the flame for a
while from it, it be suffered to cool, and when you will find it as easie to be
turned round as at the first.
From all which Experiments it is very evident, that all those Bodies, and
particularly Glass, suffers an Expansion by Heat, and that a very
considerable one, whilst they are in a state of Fusion. For Fluidity, as I
elsewhere mention, being nothing but an effect of very strong and quick
shaking motion, whereby the parts are, as it were, loosened from each other,
and consequently leave an interjacent space or vacuity; it follows, that all
those shaken Particles must necessarily take up much more room then when
they were at rest, and lay quietly upon each other. And this is further
confirmed by a Pot of boyling Alabaster, which will manifestly rise a sixth
or eighth part higher in the Pot, whilst it is boyling, then it will remain at,
both before and after it be boyled. The reason of which odd Phænomenon
(to hint it here only by the way) is this, that there is in the curious powder of
Alabaster, and other calcining Stones, a certain watery substance, which is
so fixt and included with the solid Particles, that till the heat be very
considerable they will not fly away; but after the heat is increased to such a
degree, they break out every way in vapours, and thereby so shake and
loosen the small corpuscles of the Powder from each other, that they
become perfectly of the nature of a fluid body, and one may move a stick to
and fro through it, and stir it as easily as water, and the vapours burst and
break out in bubbles just as in boyling water, and the like; whereas, both
before those watery parts are flying away, and after they are quite gone; that
is, before and after it have done boyling, all those effects cease, and a stick

is as difficultly moved to and fro in it as in sand, or the like. Which
Explication I could easily prove, had I time; but this is not a fit place for it.
To proceed therefore, I say, that the dropping of this expanded Body into
cold Water, does make the parts of the Glass suffer a double contraction:
The first is, of those parts which are neer the Surface of the Drop. For Cold,
as I said before, contracting Bodies, that is, by the abatement of the
agitating faculty the parts falling neerer together; the parts next adjoyning
to the Water must needs lose much of their motion, and impart it to the
Ambient water (which the Ebullition and commotion of it manifests) and
thereby become a solid and hard crust, whilst the innermost parts remain yet
fluid and expanded; whence, as they grow cold also by degrees, their parts
must necessarily be left at liberty to be condensed, but because of the
hardness of the outward crust, the contraction cannot be admitted that way;
but there being many very small, and before inconspicuous, bubbles in the
substance of the Glass, upon the subsiding of the parts of the Glass, the agil
substance contained in them has liberty of expanding it self a little, and
thereby those bubbles grow much bigger, which is the second Contraction.
And both these are confirmed from the appearance of the Drop it self: for as
for the outward parts, we see, first, that it is irregular and shrunk, as it were,
which is caused by the yielding a little of the hardened Skin to a
Contraction, after the very outmost Surface is settled; and as for the internal
parts, one may with ones naked Eye perceive abundance of very
conspicuous bubbles, and with the Microscope many more.
The Consideration of which Particulars will easily make the Third
Position probable, that is, that the parts of the drop will be of a very hard,
though of a rarified Texture; for if the outward parts of the Drop, by reason
of its hard crust, will indure very little Contraction, and the agil Particles,
included in those bubbles, by the losing of their agitation, by the decrease of
the Heat, lose also most part of their Spring and Expansive power; it
follows (the withdrawing of the heat being very sudden) that the parts must
be left in a very loose Texture, and by reason of the implication of the parts
one about another, which from their sluggishnes and glutinousness I
suppose to be much after the manner of the sticks in a Thorn-bush, or a
Lock of Wool; it will follow, I say, that the parts will hold each other very
strongly together, and indeavour to draw each other neerer together, and

consequently their Texture must be very hard and stiff, but very much
rarified.
And this will make probable my next Position, That the parts of the
Glass are under a kind of tension or flexure, out of which they indeavour to
extricate and free themselves, and thereby all the parts draw towards the
Center or middle, and would, if the outward parts would give way, as they
do when the outward parts cool leisurely (as in baking of Glasses) contract
the bulk of the drop into a much less compass. For since, as I proved before,
the Internal parts of the drop, when fluid, were of a very rarified Texture,
and, as it were, tos’d open like a Lock of Wool, and if they were suffered
leisurely to cool, would be again prest, as it were, close together: And since
that the heat, which kept them bended and open, is removed, and yet the
parts not suffered to get as neer together as they naturally would; It follows,
that the Particles remain under a kind of tension and flexure, and
consequently have an indeavour to free themselves from that bending and
distension, which they do, as soon as either the tip be broken, or as soon as
by a leisurely heating and cooling, the parts are nealed into another posture.
And this will make my next Position probable, that the parts of the Glass
drops are contignated together in the form of an Arch, cannot any where
yield or be drawn inwards, till by the removing of some one part of it (as it
happens in the removing one of the stones of an Arch) the whole Fabrick is
shatter’d, and falls to pieces, and each of the Springs is left at liberty,
suddenly to extricate it self: for since I have made it probable, that the
internal parts of the Glass have a contractive power inwards, and the
external parts are incapable of such a Contraction, and the figure of it being
spherical; it follows, that the superficial parts must bear against each other,
and keep one another from being condens’d into a less room, in the same
manner as the stones of an Arch conduce to the upholding each other in that
Figure. And this is made more probable by another Experiment which was
communicated to me by an excellent Person, whose extraordinary Abilities
in all kind of Knowledg, especially in that of Natural things, and his
generous Disposition in communicating, incouraged me to have recourse to
him on many occasions. The Experiment was this: Small Glass-balls (about
the bigness of that represented in the Figure &.) would, upon rubbing or
scratching the inward Surface, fly all insunder, with a pretty brisk noise;
whereas neither before nor after the inner Surface had been thus scratcht,

did there appear any flaw or crack. And putting the pieces of one of those
broken ones together again, the flaws appeared much after the manner of
the black lines on the Figure, &. These Balls were small, but exceeding
thick bubbles of Glass, which being crack’d off from the Puntilion whilst
very hot, and so suffered to cool without nealing them in the Oven over the
Furnace, do thereby (being made of white Glass, which cools much quicker
then green Glass, and is thereby made much brittler) acquire a very porous
and very brittle texture: so that if with the point of a Needle or Bodkin, the
inside of any of them be rubbed prety hard, and then laid on a Table, it will,
within a very little while, break into many pieces with a brisk noise, and
throw the parts above a span asunder on the Table: Now though the pieces
are not so small as those of a fulminating drop, yet they as plainly shew, that
the outward parts of the Glass have a great Conatus to fly asunder, were
they not held together by the tenacity of the parts of the inward Surface: for
we see as soon as those parts are crazed by hard rubbing, and thereby their
tenacity spoiled, the springiness of the more outward parts quickly makes a
divulsion, and the broken pieces will, if the concave Surface of them be
further scratcht with a Diamond, fly again into smaller pieces.
From which preceding considerations it will follow Sixthly, That the
sudden flying asunder of the parts as soon as this Arch is any where
disordered or broken, proceeds from the springing of the parts; which,
indeavouring to extricate themselves as soon as they get the liberty, they
perform it with such a quickness, that they throw one another away with
very great violence: for the Particles that compose the Crust have a Conatus
to lye further from one another, and therefore as soon as the external parts
are loosened they dart themselves outward with great violence, just as so
many Springs would do, if they were detained and fastened to the body, as
soon as they should be suddenly loosened; and the internal parts drawing
inward, they contract so violently; that they rebound back again and fly into
multitude of small shivers or sands. Now though they appear not, either to
the naked Eye, or the Microscope, yet I am very apt to think there may be
abundance of small flaws or cracks, which, by reason the strong reflecting
Air is not got between the contiguous parts, appear not. And that this may
be so, I argue from this, that I have very often been able to make a crack or
flaw, in some convenient pieces of Glass, to appear and disappear at
pleasure, according as by pressing together, or pulling asunder the

contiguous parts, I excluded or admitted the strong reflecting Air between
the parts: And it is very probable, that there may be some Body, that is
either very rarified Air, or something analogous to it, which fills the
bubbles of these drops; which I argue, first, from the roundness of them,
and next, from the vivid reflection of Light which they exhibite: Now
though I doubt not, but that the Air in them is very much rarified, yet that
there is some in them, to such as well consider this Experiment of the
disappearing of a crack upon the extruding of the Air, I suppose it will seem
more then probable.
The Seventh and last therefore that I shall prove, is, That the gradual
heating and cooling of these so extended bodies does reduce the parts of the
Glass to a looser and softer temper. And this I found by heating them, and
keeping them for a prety while very red hot in a fire; for thereby I found
them to grow a little lighter, and the small Stems to be very easily broken
and snapt any where, without at all making the drop fly; whereas before
they were so exceeding hard, that they could not be broken without much
difficulty; and upon their breaking the whole drop would fly in pieces with
very great violence. The Reason of which last seems to be, that the leisurely
heating and cooling of the parts does not only wast some part of the Glass it
self, but ranges all the parts into a better order, and gives each Particle an
opportunity of relaxing its self, and consequently neither will the parts hold
so strongly together as before, nor be so difficult to be broken: The parts
now more easily yielding, nor will the other parts fly in pieces, because the
parts have no bended Springs. The relaxation also in the temper of hardned
Steel, and hammered Metals, by nealing them in the fire, seems to proceed
from much the same cause. For both by quenching suddenly such Metals as
have vitrified parts interspers’d, as Steel has, and by hammering of other
kinds that do not so much abound with them, as Silver, Brass, &c. the parts
are put into and detained in a bended posture, which by the agitation of
Heat are shaken, and loosened, and suffered to unbend themselves.

Observ. VIII. Of the fiery Sparks struck from a
Flint or Steel.
It is a very common Experiment, by striking with a Flint against a Steel,
to make certain fiery and shining Sparks to fly out from between those two
compressing Bodies. About eight years since, upon casually reading the
Explication of this odd Phænomenon, by the most Ingenious Des Cartes, I
had a great desire to be satisfied, what that Substance was that gave such a
shining and bright Light: And to that end I spread a sheet of white Paper,
and on it, observing the place where several of these Sparks seemed to
vanish, I found certain very small, black, but glistering Spots of a movable
Substance, each of which Schem. 5.
Fig. 1. examining with my Microscope, I found to be a small round Globule;
some of which, as they looked prety small, so did they from their Surface
yield a very bright and strong reflection on that side which was next the
Light; and each look’d almost like a prety bright Iron-Ball, whose Surface
was prety regular, such as is represented by the Figure A. In this I could
perceive the Image of the Window prety well, or of a Stick, which I moved
up and down between the Light and it. Others I found, which were, as to the
bulk of the Ball, prety regularly round, but the Surface of them, as it was
not very smooth, but rough, and more irregular, so was the reflection from it
more faint and confused. Such were the Surfaces of B. C. D. and E. Some
of these I found cleft or cracked, as C, others quite broken in two and
hollow, as D. which seemed to be half the hollow shell of a Granado,
broken irregularly in pieces. Several others I found of other shapes; but that
which is represented by E, I observed to be a very big Spark of fire, which
went out upon one side of the Flint that I struck fire withall, to which it
stuck by the root F, at the end of which small Stem was fastened-on a
Hemisphere, or half a hollow Ball, with the mouth of it open from the
stemwards, so that it looked much like a Funnel, or an old fashioned Bowl
without a foot. This night, making many tryals and observations of this
Experiment, I met, among a multitude of the Globular ones which I had
observed, a couple of Instances, which are very remarkable to the
confirmation of my Hypothesis.

And the First was of a pretty big Ball fastened on to the end of a small
sliver of Iron, which Compositum seemed to be nothing else but a long thin
chip of Iron, one of whose ends was melted into a small round Globul; the
other end remaining unmelted and irregular, and perfectly Iron.
The Second Instance was not less remarkable then the First; for I found,
when a Spark went out, nothing but a very small thin long sliver of Iron or
Steel, unmelted at either end. So that it seems, that some of these Sparks are
the slivers or chips of the Iron vitrified, Others are only the slivers melted
into Balls without vitrification, And the third kind are only small slivers of
the Iron, made red-hot with the violence of the stroke given on the Steel by
the Flint.
He that shall diligently examine the Phænomena of this Experiment, will,
I doubt not, find cause to believe, that the reason I have heretofore given of
it, is the true and genuine cause of it, namely, That the Spark, appearing so
bright in the falling, is nothing else but a small piece of the Steel or Flint,
but most commonly of the Steel, which by the violence of the stroke is at the
same time sever’d and heat red-hot, and that sometimes to such a degree,
as to make it melt together into a small Globule of Steel; and sometimes
also is that heat so very intense, as further to melt it and vitrifie it; but many
times the heat is so gentle, as to be able to make the sliver only red hot,
which notwithstanding falling upon the tinder (that is only a very curious
small Coal made of the small threads of Linnen burnt to coals and char’d) it
easily sets it on fire. Nor will any part of this Hypothesis seem strange to
him that considers, First, that either hammering, or filing or otherwise
violently rubbing of Steel, will presently make it so hot as to be able to burn
ones fingers. Next, that the whole force of the stroke is exerted upon that
small part where the Flint and Steel first touch: For the Bodies being each
of them so very hard, the puls cannot be far communicated, that is, the parts
of each can yield but very little, and therefore the violence of the
concussion will be exerted on that piece of Steel which is cut off by the
Flint. Thirdly, that the filings or small parts of Steel are very apt, as it were,
to take fire, and are presently red hot, that is, there seems to be a very
combustible sulphureous Body in Iron or Steel, which the Air very readily
preys upon, as soon as the body is a little violently heated.

And this is obvious in the filings of Steel or Iron cast through the flame
of a Candle; for even by that sudden transitus of the small chips of Iron,
they are heat red hot, and that combustible sulphureous Body is presently
prey’d upon and devoured by the aereal incompassing Menstruum, whose
office in this Particular I have shewn in the Explication of Charcole.
And in prosecution of this Experiment, having taken the filings of Iron
and Steel, and with the point of a Knife cast them through the flame of a
Candle, I observed where some conspicuous shining Particles fell, and
looking on them with my Microscope, I found them to be nothing else but
such round Globules, as I formerly found the Sparks struck from the Steel
by a stroke to be, only a little bigger; and shaking together all the filings
that had fallen upon the sheet of Paper underneath and observing them with
the Microscope, I found a great number of small Globules, such as the
former, though there were also many of the parts that had remained
untoucht and rough filings or chips of Iron. So that, it seems, Iron does
contain a very combustible sulphureous Body, which is, in all likelihood,
one of the causes of this Phænomenon, and which may be perhaps very
much concerned in the business of its hardening and tempering: of which
somewhat is said in the Description of Muscovy-glass.
So that, these things considered, we need not trouble our selves to find
out what kind of Pores they are, both in the Flint and Steel, that contain the
Atoms of fire, nor how those Atoms come to be hindred from running all
out, when a dore or passage in their Pores is made by the concussion: nor
need we trouble our selves to examine by what Prometheus the Element of
Fire comes to be fetcht down from above the Regions of the Air, in what
Cells or Boxes it is kept, and what Epimetheus lets it go: Nor to consider
what it is that causes so great a conflux of the atomical Particles of Fire,
which are said to fly to a flaming Body, like Vultures or Eagles to a
putrifying Carcass, and there to make a very great pudder. Since we have
nothing more difficult in this Hypothesis to conceive, first, as to the
kindling of Tinder, then how a large Iron-bullet, let fall red or glowing hot
upon a heap of Small-coal, should set fire to those that are next to it first:
Nor secondly, is this last more difficult to be explicated, then that a Body, as
Silver for Instance, put into a weak Menstruum, as unrectified Aqua fortis
should, when it is put in a great heat, be there dissolved by it, and not
before; which Hypothesis is more largely explicated in the Description of

Charcoal. To conclude, we see by this Instance, how much Experiments
may conduce to the regulating of Philosophical notions. For if the most
Acute Des Cartes had applied himself experimentally to have examined
what substance it was that caused that shining of the falling Sparks struck
from a Flint and a Steel, he would certainly have a little altered his
Hypothesis, and we should have found, that his Ingenious Principles would
have admitted a very plausible Explication of this Phænomenon; whereas
by not examining so far as he might, he has set down an Explication which
Experiment do’s contradict.
But before I leave this Description, I must not forget to take notice of the
Globular form into which each of these is most curiously formed. And this
Phænomenon, as I have elsewhere more largely shewn, proceeds from a
propriety which belongs to all kinds of fluid Bodies more or less, and is
caused by the Incongruity of the Ambient and included Fluid, which so acts
and modulates each other, that they acquire, as neer as is possible, a
spherical or globular form, which propriety and several of the Phænomena
that proceed from it, I have more fully explicated in the sixth Observation.
One Experiment, which does very much illustrate my present
Explication, and is in it self exceeding pretty, I must not pass by: And that is
a way of making small Globules or Balls of Lead, or Tin, as small almost as
these of Iron or Steel, and that exceeding easily and quickly, by turning the
filings or chips of those Metals also into perfectly round Globules. The way,
in short, as I received it from the Learned Physitian Doctor I.G. is this;
Reduce the Metal you would thus shape, into exceeding fine filings, the
finer the filings are, the finer will the Balls be: Stratifie these filings with
the fine and well dryed powder of quick Lime in a Crucible proportioned to
the quantity you intend to make: When you have thus filled your Crucible,
by continual stratifications of the filings and powder, so that, as neer as
may be, no one of the filings may touch another, place the Crucible in a
gradual fire, and by degrees let it be brought to a heat big enough to make
all the filings, that are mixt with the quick Lime, to melt, and no more; for if
the fire be too hot, many of these filings will joyn and run together; whereas
if the heat be proportioned, upon washing the Lime-dust in fair Water, all
those small filings of the Metal will subside to the bottom in a most curious

powder, consisting all of exactly round Globules, which, if it be very fine, is
very excellent to make Hour-glasses of.
Now though quick Lime be the powder that this direction makes choice
of, yet I doubt not, but that there may be much more convenient ones found
out, one of which I have made tryal of, and found very effectual; and were
it not for discovering, by the mentioning of it, another Secret, which I am
not free to impart, I should have here inserted it.

Observ. IX. Of the Colours observable in Muscovy-
Glass, and other thin Bodies.
Moscovy-glass, or Lapis specularis, is a Body that seems to have as
many Curiosities in its Fabrick as any common Mineral I have met with: for
first, It is transparent to a great thickness: Next, it is compounded of an
infinite number of thin flakes joyned or generated one upon another so
close & smooth, as with many hundreds of them to make one smooth and
thin Plate of a transparent flexible substance, which with care and diligence
may be slit into pieces so exceedingly thin as to be hardly perceivable by
the eye, and yet even those, which I have thought the thinnest, I have with a
good Microscope found to be made up of many other Plates, yet thinner;
and it is probable, that, were our Microscopes much better, we might much
further discover its divisibility. Nor are these flakes only regular as to the
smoothness of their Surfaces, but thirdly, In many Plates they may be
perceived to be terminated naturally with edges of the figure of a
Rhomboeid. This Figure is much more conspicuous in our English talk,
much whereof is found in the Lead Mines, and is commonly called Spar,
and Kauck, which is of the same kind of substance with the Selenitis, but is
seldom found in so large flakes as that is, nor is it altogether so tuff, but is
much more clear and transparent, and much more curiously shaped, and yet
may be cleft and flak’d like the other Selenitis. But fourthly, this stone has a
property, which in respect of the Microscope, is more notable, and that is,
that it exhibits several appearances of Colours, both to the naked Eye, but
much more conspicuously to the Microscope; for the exhibiting of which, I
took a piece of Muscovy-glass, and splitting or cleaving it into thin Plates, I
found that up and down in several parts of them I could plainly perceive
several white specks or flaws, and others diversly coloured with all the
Colours of the Rainbow; and with the Microscope I could perceive, that
these Colours were ranged in rings that incompassed the white speck or
flaw, and were round or irregular, according to the shape of the spot which
they terminated; and the position of Colours, in respect of one another, was
the very same as in the Rainbow. The consecution of those Colours from the
middle of the spot outward being Blew, Purple, Scarlet, Yellow, Green;

Blew, Purple, Scarlet, and so onwards, sometimes half a score times
repeated, that is, there appeared six, seven, eight, nine or ten several
coloured rings or lines, each incircling the other, in the same manner as I
have often seen a very vivid Rainbow to have four or five several Rings of
Colours, that is, accounting all the Gradations between Red and Blew for
one: But the order of the Colours in these Rings was quite contrary to the
primary or innermost Rainbow, and the same with those of the secondary or
outermost Rainbow; these coloured Lines or Irises, as I may so call them,
were some of them much brighter then others, and some of them also very
much broader, they being some of them ten, twenty, nay, I believe, neer a
hundred times broader then others; and those usually were broadest which
were neerest the center or middle of the flaw. And oftentimes I found, that
these Colours reacht to the very middle of the flaw, and then there appeared
in the middle a very large spot, for the most part, all of one colour, which
was very vivid, and all the other Colours incompassing it, gradually
ascending, and growing narrower towards the edges, keeping the same
order, as in the secundary Rainbow, that is, if the middle were Blew, the
next incompassing it would be a Purple, the third a Red, the fourth a
Yellow, &c. as above; if the middle were a Red, the next without it would
be a Yellow, the third a Green, the fourth a Blew, and so onward. And this
order it alwayes kept whatsoever were the middle Colour.
There was further observable in several other parts of this Body, many
Lines or Threads, each of them of some one peculiar Colour, and those so
exceedingly bright and vivid, that it afforded a very pleasant object through
the Microscope. Some of these threads I have observed also to be pieced or
made up of several short lengths of differently coloured ends (as I may so
call them) as a line appearing about two inches long through the
Microscope, has been compounded of about half an inch of a Peach colour,
⅛ of a lovely Grass-green, ¾ of an inch more of a bright Scarlet, and the
rest of the line of a Watchet blew. Others of them were much otherwise
coloured; the variety being almost infinite. Another thing which is very
observable, is, that if you find any place where the colours are very broad
and conspicuous to the naked eye, you may, by pressing that place with
your finger, make the colours change places, and go from one part to
another.

There is one Phænomenon more, which may, if care be used, exhibit to
the beholder, as it has divers times to me, an exceeding pleasant, and not
less instructive Spectacle; And that is, if curiosity and diligence be used,
you may so split this admirable Substance, that you may have pretty large
Plates (in companion of those smaller ones which you may observe in the
Rings) that are perhaps an ⅛ or a ⅙ part of an inch over, each of them
appearing through the Microscope most curiously, intirely, and uniformly
adorned with some one vivid colour: this, if examined with the Microscope,
may be plainly perceived to be in all parts of it equally thick. Two, three, or
more of these lying one upon another, exhibit oftentimes curious
compounded colours, which produce such a Compositum, as one would
scarce imagine should be the result of such ingredients: As perhaps a faint
yellow and a blew may produce a very deep purple. But when anon we
come to the more strict examination of these Phænomena, and to inquire
into the causes and reasons of these productions, we shall, I hope, make it
more conceivable how they are produced, and shew them to be no other
then the natural and necessary effects arising from the peculiar union of
concurrent causes.
These Phænomena, being so various, and so truly admirable, it will
certainly be very well worth our inquiry, to examine the causes and reasons
of them, and to consider, whether from these causes demonstratively
evidenced, may not be deduced the true causes of the production of all kind
of Colours. And I the rather now do it, instead of an Appendix or Digression
to this History, then upon the occasion of examining the Colours in
Peacocks, or other Feathers, because this Subject, as it does afford more
variety of particular Colours, so does it afford much better wayes of
examining each circumstance. And this will be made manifest to him that
considers, first, that this laminated body is more simple and regular then the
parts of Peacocks feathers, this consisting only of an indefinite number of
plain and smooth Plates, heaped up, or incumbent on each other. Next, that
the parts of this body are much more manageable, to be divided or joyned,
then the parts of a Peacocks feather, or any other substance that I know. And
thirdly, because that in this we are able from a colourless body to produce
several coloured bodies, affording all the variety of Colours imaginable:
And several others, which the subsequent Inquiry will make manifest.

To begin therefore, it is manifest from several circumstances, that the
material cause of the apparition of these several Colours, is some Lamina
or Plate of a transparent or pellucid body of a thickness very determinate
and proportioned according to the greater or less refractive power of the
pellucid body. And that this is so, abundance of Instances and particular
Circumstances will make manifest.
As first, if you take any small piece of the Muscovy-glass, and with a
Needle, or some other convenient Instrument, cleave it oftentimes into
thinner and thinner Laminæ, you shall find, that till you come to a
determinate thinness of them, they shall all appear transparent and
colourless, but if you continue to split and divide them further, you shall
find at last, that each Plate, after it comes to such a determinate thickness,
shall appear most lovely ting’d or imbued with a determinate colour. If
further, by any means you so flaw a pretty thick piece, that one part does
begin to cleave a little from the other, and between those two there be by
any means gotten some pellucid medium, those laminated pellucid bodies
that fill that space, shall exhibit several Rainbows or coloured Lines, the
colours of which will be disposed and ranged according to the various
thicknesses of the several parts of that Plate. That this is so, is yet further
confirmed by this Experiment.
Take two small pieces of ground and polisht Looking-glass-plate, each
about the bigness of a shilling, take these two dry, and with your fore-
fingers and thumbs press them very hard and close together, and you shall
find, that when they approach each other very near, there will appear
several Irises or coloured Lines, in the same manner almost as in the
Muscovy-glass; and you may very easily change any of the Colours of any
part of the interposed body, by pressing the Plates closer and harder
together, or leaving them more lax; that is, a part which appeared coloured
with a red, may be presently ting’d with a yellow, blew, green, purple, or
the like, by altering the appropinquation of the terminating Plates. Now that
air is not necessary to be the interposed body, but that any other transparent
fluid will do much the same, may be tryed by wetting those approximated
Surfaces with Water, or any other transparent Liquor, and proceeding with it
in the same manner as you did with the Air; and you will find much the like
effect, only with this difference, that those comprest bodies, which differ
most, in their refractive quality, from the compressing bodies, exhibit the

most strong and vivid tinctures. Nor is it necessary, that this laminated and
ting’d body should be of a fluid substance, any other substance, provided it
be thin enough and transparent, doing the same thing: this the Laminæ of
our Muscovy-glass hint; but it may be confirm’d by multitudes of other
Instances.
And first, we shall find, that even Glass it self may, by the help of a
Lamp, be blown thin enough to produce these Phænomena of Colours:
which Phænomena accidentally happening, as I have been attempting to
frame small Glasses with a Lamp, did not a little surprize me at first, having
never heard or seen any thing of it before; though afterwards comparing it
with the Phænomena, I had often observed in those Bubbles which Children
use to make with Soap-water, I did the less wonder; especially when upon
Experiment I found, I was able to produce the same Phænomena in thin
Bubbles made with any other transparent Substance. Thus have I produced
them with Bubbles of Pitch, Rosin, Colophony, Turpentine, Solutions of
several Gums, as Gum-Arabick in water; any glutinous Liquor, as Wort,
Wine, Spirit of Wine, Oyl of Turpentine, Glare of Snails, &c.
It would be needless to enumerate the several Instances, these being
enough to shew the generality or universality of this propriety. Only I must
not omit, that we have instances also of this kind even in metalline Bodies
and animal; for those several Colours which are observed to follow each
other upon the polisht surface of hardned Steel, when it is by a sufficient
degree of heat gradually tempered or softened, are produced, from nothing
else but a certain thin Lamina of a vitrum or vitrified part of the Metal,
which by that degree of heat, and the concurring action of the ambient Air,
is driven out and fixed on the surface of the Steel.
And this hints to me a very probable (at least, if not the true) cause of the
hardning and tempering of Steel, which has not, I think, been yet given, nor,
that I know of been so much as thought of by any. And that is this, that the
hardness of it arises from a greater proportion of a vitrified Substance
interspersed through the pores of the Steel. And that the tempering or
softning of it arises from the proportionate or smaller parcels of it left
within those pores. This will seem the more probable, if we consider these
Particulars.

First, That the pure parts of Metals are of themselves very flexible and
tuff; that is, will indure bending and hammering, and yet retain their
continuity.
Next, That the Parts of all vitrified Substances, as all kinds of Glass, the
Scoria of Metals, &c. are very hard, and also very brittle, being neither
flexible nor malleable, but may by hammering or beating be broken into
small parts or powders.
Thirdly, That all Metals (excepting Gold and Silver, which do not so
much with the bare fire, unless assisted by other saline Bodies) do more or
less vitrifie by the strength of fire, that is, are corroded by a Saline
Substance, which I elsewhere shew to be the true cause of fire; and are
thereby, as by several other Menstruums converted into Scoria; And this is
called, calcining of them, by Chimists. Thus Iron and Copper by heating
and quenching do turn all of them by degrees into Scoria, which are
evidently vitrified Substances, and unite with Glass, and are easily fusible;
and when cold, very hard, and very brittle.
Fourthly, That most kind of Vitrifications or Calcinations are made by
Salts, uniting and incorporating with the metalline Particles. Nor do I know
any one calcination wherein a Saline body may not, with very great
probability, be said to be an agent or coadjutor.
Fifthly, That Iron is converted into Steel by means of the incorporation of
certain salts, with which it is kept a certain time in the fire.
Sixthly, That any Iron may, in a very little time, be case hardned, as the
Tradesmen call it, by casing the iron to be hardned with clay, and putting
between the clay and iron a good quantity of a mixture of Urine, Soot, Sea-
salt, and Horses hoofs (all which contein great quantities of Saline bodies)
and then putting the case into a good strong fire, and keeping it in a
considerable degree of heat for a good while, and afterwards heating, and
quenching or cooling it suddenly in cold water.
Seventhly, That all kind of vitrify’d substances, by being suddenly
cool’d, become very hard and brittle. And thence arises the pretty
Phænomena of the Glass Drops, which I have already further explained in
its own place.

Eighthly, That those metals which are not so apt to vitrifie, do not acquire
any hardness by quenching in water, as Silver, Gold, &c.
These considerations premis’d, will, I suppose, make way for the more
easie reception of this following Explication of the Phænomena of hardned
and temper’d Steel. That Steel is a substance made out of Iron, by means of
a certain proportionate Vitrification of several parts, which are so curiously
and proportionately mixt with the more tough and unalter’d parts of the
Iron, that when by the great heat of the fire this vitrify’d substance is
melted, and consequently rarify’d, and thereby the pores of the Iron are
more open, if then by means of dipping it in cold water it be suddenly cold,
and the parts hardned, that is, stay’d in that same degree of Expansion they
were in when hot, the parts become very hard and brittle, and that upon the
same account almost as small parcels of glass quenched in water grow
brittle, which we have already explicated. If after this the piece of Steel be
held in some convenient heat, till by degrees certain colours appear upon
the surface of the brightned metal, the very hard and brittle tone of the
metal, by degrees relaxes and becomes much more tough and soft; namely,
the action of the heat does by degrees loosen the parts of the Steel that were
before streached or set atilt as it were, and stayed open by each other,
whereby they become relaxed and set at liberty, whence some of the more
brittle interjacent parts are thrust out and melted into a thin skin on the
surface of the Steel, which from no colour increases to a deep Purple, and
so onward by these gradations or consecutions, White, Yellow, Orange,
Minium, Scarlet, Purple, Blew, Watchet, &c. and the parts within are more
conveniently, and proportionately mixt; and so they gradually subside into a
texture which is much better proportion’d and closer joyn’d, whence that
rigidness of parts ceases, and the parts begin to acquire their former
ductilness.
Now, that ’tis nothing but the vitrify’d metal that sticks upon the surface
of the colour’d body, is evident from this, that if by any means it be scraped
and rubb’d off, the metal underneath it is white and clear; and if it be kept
longer in the fire, so as to increase to a considerable thickness, it may, by
blows, be beaten off in flakes. This is further confirm’d by this observable,
that that Iron or Steel will keep longer from rusting which is covered with
this vitrify’d case: Thus also Lead will, by degrees, be all turn’d into a

litharge; for that colour which covers the top being scum’d or shov’d aside,
appears to be nothing else but a litharge or vitrify’d Lead.
This is observable also in some sort, on Brass, Copper, Silver, Gold, Tin,
but is most conspicuous in Lead: all those Colours that cover the surface of
the Metal being nothing else, but a very thin vitrifi’d part of the heated
Metal.
The other Instance we have, is in Animal bodies, as in Pearls, Mother of
Pearl-shels, Oyster-shels, and almost all other kinds of stony shels
whatsoever. This have I also sometimes with pleasure observ’d even in
Muscles and Tendons. Further, if you take any glutinous substance and run
it exceedingly thin upon the surface of a smooth glass or a polisht metaline
body, you shall find the like effects produced: and in general, wheresoever
you meet with a transparent body thin enough, that is terminated by
reflecting bodies of differing refractions from it, there will be a production
of these pleasing and lovely colours.
Nor is it necessary, that the two terminating Bodies should be both of the
same kind, as may appear by the vitrified Laminæ on Steel, Lead, and other
Metals, one surface of which Laminæ is contiguous to the surface of the
Metal, the other to that of the Air.
Nor is it necessary, that these colour’d Laminæ should be of an even
thickness, that is, should have their edges and middles of equal thickness, as
in a Looking-glass-plate, which circumstance is only requisite to make the
Plate appear all of the same colour; but they may resemble a Lens, that is,
have their middles thicker then their edges; or else a double concave, that is,
be thinner in the middle then at the edges; in both which cases there will be
various coloured rings or lines, with differing consecutions or orders of
Colours; the order of the first from the middle outwards being Red, Yellow,
Green, Blew, &c. And the latter quite contrary.
But further, it is altogether necessary, that the Plate, in the places where
the Colours appear, should be of a determinate thickness: First, It must not
be more then such a thickness, for when the Plate is increased to such a
thickness, the Colours cease; and besides, I have seen in a thin piece of
Muscovy-glass, where the two ends of two Plates, which appearing both
single, exhibited two distinct and differing Colours; but in that place where

they were united, and constituted one double Plate (as I may call it) they
appeared transparent and colourless. Nor, Secondly, may the Plates be
thinner then such a determinate cize; for we alwayes find, that the very
outmost Rim of these flaws is terminated in a white and colourless Ring.
Further, in this Production of Colours there is no need of a determinate
Light of such a bigness and no more, nor of a determinate position of that
Light, that it should be on this side, and not on that side; nor of a
terminating shadow, as in the Prisme, and Rainbow, or Water-ball: for we
find, that the Light in the open Air, either in or out of the Sun-beams, and
within a Room, either from one or many Windows, produces much the
same effect: only where the Light is brightest, there the Colours are most
vivid. So does the light of a Candle, collected by a Glass-ball. And further, it
is all one whatever side of the coloured Rings be towards the light; for the
whole Ring keeps its proper Colours from the middle outwards in the same
order as I before related, without varying at all, upon changing the position
of the light.
But above all it is most observable, that here are all kind of Colours
generated in a pellucid body, where there is properly no such refraction as
Des Cartes supposes his Globules to acquire a verticity by: For in the plain
and even Plates it is manifest, that the second refraction (according to Des
Cartes his Principles in the fifth Section of the eighth Chapter of his
Meteors) does regulate and restore the supposed turbinated Globules unto
their former uniform motion. This Experiment therefore will prove such a
one as our thrice excellent Verulam calls Experimentum Crucis, serving as a
Guide or Land-mark, by which to direct our course in the search after the
true cause of Colours. Affording us this particular negative Information, that
for the production of Colours there is not necessary either a great refraction,
as in the Prisme; nor Secondly, a determination of Light and shadow, such
as is both in the Prisme and Glass-ball. Now that we may see likewise what
affirmative and positive Instruction it yields, it will be necessary, to
examine it a little more particularly and strictly; which that we may the
better do, it will be requisite to premise somewhat in general concerning the
nature of Light and Refraction.
And first for Light it seems very manifest, that there is no luminous Body
but has the parts of it in motion more or less.

First, That all kind of fiery burning Bodies have their parts in motion, I
think, will be very easily granted me. That the spark struck from a Flint and
Steel is in a rapid agitation, I have elsewhere made probable. And that the
Parts of rotten Wood, rotten Fish and the like, are also in motion, I think,
will as easily be conceded by those, who consider, that those parts never
begin to shine till the Bodies be in a state of putrefaction; and that is now
generally granted by all, to be caused by the motion of the parts of
putrifying bodies. That the Bononian stone shines no longer then it is either
warmed by the Sun-beams, or by the flame of a Fire or of a Candle, is the
general report of those that write of it, and of others that have seen it. And
that heat argues a motion of the internal parts is (as I said before) generally
granted.
But there is one Instance more, which was first shewn to the Royal
Society by Mr. Clayton a worthy Member thereof, which does make this
Assertion more evident then all the rest: And that is, That a Diamond being
rub’d, struck or heated in the dark, shines for a pretty while after, so long as
that motion, which is imparted by any of those Agents, remains (in the same
manner as a Glass, rubb’d, struck, or (by a means which I shall elsewhere
mention) heated, yields a sound which lasts as long as the vibrating motion
of that sonorous body) several Experiments made on which Stone, are since
published in a Discourse of Colours, by the truly honourable Mr. Boyle.
What may be said of those Ignes fatui that appear in the night, I cannot so
well affirm, having never had the opportunity to examine them my self, nor
to be inform’d by any others that had observ’d them: And the relations of
them in Authors are so imperfect, that nothing can be built on them. But I
hope I shall be able in another place to make it at least very probable, that
there is even in those also a Motion which causes this effect. That the
shining of Sea-water proceeds from the same cause, may be argued from
this, That it shines not till either it be beaten against a Rock, or be some
other wayes broken or agitated by Storms, or Oars, or other percussing
bodies. And that the Animal Energies or Spirituous agil parts are very
active in Cats eyes when they shine, seems evident enough, because their
eyes never shine but when they look very intensly either to find their prey,
or being hunted in a dark room, when they seek after their adversary, or to
find a way to escape. And the like may be said of the shining Bellies of

Gloworms; since ’tis evident they can at pleasure either increase or
extinguish that Radiation.
It would be somewhat too long a work for this place Zetetically to
examine, and positively to prove, what particular kind of motion it is that
must be the efficient of Light; for though it be a motion, yet ’tis not every
motion that produces it, since we find there are many bodies very violently
mov’d, which yet afford not such an effect; and there are other bodies,
which to our other senses, seem not mov’d so much, which yet shine. Thus
Water and quick-silver, and most other liquors heated, shine not; and
several hard bodies, as Iron, Silver, Brass, Copper, Wood, &c. though very
often struck with a hammer, shine not presently, though they will all of
them grow exceeding hot; whereas rotten Wood, rotten Fish, Sea-water,
Gloworms, &c. have nothing of tangible heat in them, and yet (where there
is no stronger light to affect the Sensory) they shine some of them so
Vividly, that one may make a shift to read by them.
It would be too long, I say, here to insert the discursive progress by
which I inquir’d after the proprieties of the motion of Light, and therefore I
shall only add the result.
And, First, I found it ought to be exceeding quick, such as those motions
of fermentation and putrefaction, whereby, certainly, the parts are exceeding
nimbly and violently mov’d; and that, because we find those motions are
able more minutely to shatter and divide the body, then the most violent
heats or menstruums we yet know. And that fire is nothing else but such a
dissolution of the Burning body, made by the most universal menstruum of
all sulphureous bodies, namely, the Air, we shall in an other place of this
Tractate endeavour to make probable. And that, in all extreamly hot shining
bodies, there is a very quick motion that causes Light, as well as a more
robust that causes Heat, may be argued from the celerity wherewith the
bodyes are dissolv’d.
Next, it must be a Vibrative motion. And for this the newly mention’d
Diamond affords us a good argument; since if the motion of the parts did
not return, the Diamond must after many rubbings decay and be wasted: but
we have no reason to suspect the latter, especially if we consider the
exceeding difficulty that is found in cutting or wearing away a Diamond.

And a Circular motion of the parts is much more improbable, since, if that
were granted, and they be suppos’d irregular and Angular parts, I see not
how the parts of the Diamond should hold so firmly together, or remain in
the same sensible dimensions, which yet they do. Next, if they be Globular,
and mov’d only with a turbinated motion, I know not any cause that can
impress that motion upon the pellucid medium, which yet is done. Thirdly,
any other irregular motion of the parts one amongst another, must
necessarily make the body of a fluid consistence, from which it is far
enough. It must therefore be a Vibrating motion.
And Thirdly, That it is a very short-vibrating motion, I think the instances
drawn from the shining of Diamonds will also make probable. For a
Diamond being the hardest body we yet know in the World, and
consequently the least apt to yield or bend, must consequently also have its
vibrations exceeding short.
And these, I think, are the three principal proprieties of a motion,
requisite to produce the effect call’d Light in the Object.
The next thing we are to consider, is the way or manner of the trajection
of this motion through the interpos’d pellucid body to the eye: And here it
will be easily granted,
First, That it must be a body susceptible and impartible of this motion
that will deserve the name of a Transparent. And next, that the parts of such
a body must be Homogeneous, or of the same kind. Thirdly, that the
constitution and motion of the parts must be such, that the appulse of the
luminous body may be communicated or propagated through it to the
greatest imaginable distance in the least imaginable time, though I see no
reason to affirm, that it must be in an instant: For I know not any one
Experiment or observation that does prove it. And, whereas it may be
objected, That we see the Sun risen at the very instant when it is above the
sensible Horizon, and that we see a Star hidden by the body of the Moon at
the same instant, when the Star, the Moon, and our Eye are all in the same
line; and the like Observations, or rather suppositions, may be urg’d. I have
this to answer, That I can as easily deny as they affirm; for I would fain
know by what means any one can be assured any more of the Affirmative,
then I of the Negative. If indeed the propagation were very slow, ’tis

possible something might be discovered by Eclypses of the Moon; but
though we should grant the progress of the light from the Earth to the
Moon, and from the Moon back to the Earth again to be full two Minutes in
performing, I know not any possible means to discover it; nay, there may be
some instances perhaps of Horizontal Eclypses that may seem very much to
favour this supposition of the slower progression of Light then most
imagine. And the like may be said of the Eclypses of the Sun, &c. But of
this only by the by. Fourthly, That the motion is propagated every way
through an Homogeneous medium by direct or straight lines extended every
way like Rays from the center of a Sphere. Fifthly, in an Homogeneous
medium this motion is propagated every way with equal velocity, whence
necessarily every pulse or vibration of the luminous body will generate a
Sphere, which will continually increase, and grow bigger, just after the
same manner (though indefinitely swifter) as the waves or rings on the
surface of the water do swell into bigger and bigger circles about a point of
it, where, by the sinking of a Stone the motion was begun, whence it
necessarily follows, that all the parts of these Spheres undulated through an
Homogeneous medium cut the Rays at right angles.
But because all transparent mediums are not Homogeneous to one
another, therefore we will next examine how this pulse or motion will be
propagated through differingly transparent mediums. And here, according to
the most acute and excellent Philosopher Des Cartes, I suppose the sign of
the angle of inclination in the first medium to be to the sign of refraction in
the second, As the density of the first, to the density of the second. By
density, I mean not the density in respect of gravity (with which the
refractions or transparency of mediums hold no proportion) but in respect
onely to the trajection of the Rays of light, in which respect they only differ
in this; that the one propagates the pulse more easily and weakly, the other
more slowly, but more strongly. But as for the pulses themselves, they will
by the refraction acquire another propriety, which we shall now endeavour
to explicate.
Schem. 6.
Fig. 1.

We will suppose therefore in the first Figure ACFD to be a physical Ray,
or ABC and DEF to be two Mathematical Rays, trajected from a very
remote point of a luminous body through an Homogeneous transparent

medium LLL, and DA, EB, FC, to be small portions of the orbicular
impulses which must therefore cut the Rays at right angles; these Rays
meeting with the plain surface NO of a medium that yields an easier
transitus to the propagation of light, and falling obliquely on it, they will in
the medium MMM be refracted towards the perpendicular of the surface.
And because this medium is more easily trajected then the former by a
third, therefore the point C of the orbicular pulse FC will be mov’d to H
four spaces in the same time that F the other end of it is mov’d to G three
spaces, therefore the whole refracted pulse GH shall be oblique to the
refracted Rays CHK and GI; and the angle GHC shall be an acute, and so
much the more acute by how much the greater the refraction be, then which
nothing is more evident, for the sign of the inclination is to the sign of
refraction as GF to TC the distance between the point C and the
perpendicular from G on CK, which being as four to three, HC being longer
then GF is longer also then TC, therefore the angle GHC is less than GTC.
So that henceforth the parts of the pulses GH and IK are mov’d ascew, or
cut the Rays at oblique angles.
It is not my business in this place to set down the reasons why this or that
body should impede the Rays more, others less: as why Water should
transmit the Rays more easily, though more weakly than air. Onely thus
much in general I shall hint, that I suppose the medium MMM to have less
of the transparent undulating subtile matter, and that matter to be less
implicated by it, whereas LLL I suppose to contain a greater quantity of the
fluid undulating substance, and this to be more implicated with the particles
of that medium.
But to proceed, the same kind of obliquity of the Pulses and Rays will
happen also when the refraction is made out of a more easie into a more
difficult mediu; as by the calculations of GQ & CSR which are refracted
from the perpendicular. In both which calculations ’tis obvious to observe,
that always that part of the Ray towards which the refraction is made has
the end of the orbicular pulse precedent to that of the other side. And
always, the oftner the refraction is made the same way, Or the greater the
single refraction is, the more is this unequal progress. So that having found
this odd propriety to be an inseparable concomitant of a refracted Ray, not
streightned by a contrary refraction, we will next examine the refractions of

the Sun-beams, as they are suffer’d onely to pass through a small passage,
obliquely out of a more difficult, into a more easie medium.
Schem. 6.
Fig. 2.

Let us suppose therefore ABC in the second Figure to represent a large
Chemical Glass-body about two foot long, filled with very fair Water as
high as AB, and inclin’d in a convenient posture with B towards the Sun:
Let us further suppose the top of it to be cover’d with an opacous body, all
but the hole ab, through which the Sun-beams are suffer’d to pass into the
Water, and are thereby refracted to cdef, against which part, if a Paper be
expanded on the outside, there will appear all the colours of the Rainbow,
that is, there will be generated the two principal colours, Scarlet and Blue,
and all the intermediate ones which arise from the composition and
dilutings of these two, that is, cd shall exhibit a Scarlet, which toward d is
diluted into a Yellow; this is the refraction of the Ray, ik, which comes from
the underside of the Sun; and the Ray ef shall appear of a deep Blue, which
is gradually towards e diluted into a pale Watchet-blue. Between d and e the
two diluted colours. Blue and Yellow are mixt and compounded into a
Green; and this I imagine to be the reason why Green is so acceptable a
colour to the eye, and that either of the two extremes are, if intense, rather a
little offensive, namely, the being plac’d in the middle between the two
extremes, and compounded out of both those, diluted also, or somewhat
qualifi’d, for the composition, arising from the mixture of the two extremes
undiluted, makes a Purple, which though it be a lovely colour, and pretty
acceptable to the eye, yet is it nothing comparable to the ravishing pleasure
with which a curious and well tempered Green affects the eye. If removing
the Paper, the eye be plac’d against cd, it will perceive the lower side of the
Sun (or a Candle at night which is much better, because it offends not the
eye, and is more easily manageable) to be of a deep Red, and if against ef it
will perceive the upper part of the luminous body to be of a deep Blue; and
these colours will appear deeper and deeper, according as the Rays from the
luminous body fall more obliquely on the surface of the Water, and thereby
suffer a greater refraction, and the more distinct, the further cdef is removed
from the trajecting hole.
So that upon the whole, we shall find that the reason of the Phænomena
seems to depend upon the obliquity of the orbicular pulse, to the Lines of

Radiation, and in particular, that the Ray cd which constitutes the Scarlet
has its inner parts, namely those which are next to the middle of the
luminous body, precedent to the outermost which are contiguous to the dark
and unradiating skie. And that the Ray ef which gives a Blue, has its
outward part, namely, that which is contiguous to the dark skie precedent to
the pulse from the innermost, which borders on the bright area of the
luminous body.
We may observe further, that the cause of the diluting of the colours
towards the middle, proceeds partly from the wideness of the hole through
which the Rays pass, whereby the Rays from several parts of the luminous
body, fall upon many of the same parts between c and f as is more manifest
by the Figure: And partly also from the nature of the refraction it self, for
the vividness or strength of the two terminating colours, arising chiefly as
we have seen, from the very great difference that is betwixt the outsides of
those oblique undulations & the dark Rays circumambient, and that
disparity betwixt the approximate Rays, decaying gradually: the further
inward toward the middle of the luminous body they are remov’d, the more
must the colour approach to a white or an undisturbed light.
Upon the calculation of the refraction and reflection from a Ball of Water
or Glass, we have much the same Phænomena, namely, an obliquity of the
undulation in the same manner as we have found it here. Which, because it
is very much to our present purpose, and affords such an Instancia crucis,
as no one that I know has hitherto taken notice of, I shall further examine.
For it does very plainly and positively distinguish, and shew, which of the
two Hypotheses, either the Cartesian or this is to be followed, by affording
a generation of all the colors in the Rainbow, where according to the
Cartesian Principles there should be none at all generated. And secondly,
by affording an instance that does more closely confine the cause of these
Phænomena of colours to this present Hypothesis.
And first, for the Cartesian, we have this to object against it, That
whereas he says (Meteorum Cap. 8. Sect. 5.) Sed judicabam unicam
(refractione scilicet) ad minimum requiri, & quidem talem ut ejus effectus
aliâ contrariâ (refractione) non destruatur: Nam experientia docet si
superficies NM & NP (nempe refringentes) Parallelæ forent, radios
tantundem per alteram iterum erectos quantum per unam frangerentur,

nullos colores depicturos; This Principle of his holds true indeed in a prisme
where the refracting surfaces are plain, but is contradicted by the Ball or
Cylinder, whether of Water or Glass, where the refracting surfaces are
Orbicular or Cylindrical. For if we examine the passage of any Globule or
Ray of the primary Iris, we shall find it to pass out of the Ball or Cylinder
again, with the same inclination and refraction that it enter’d in withall, and
that that last refraction by means of the intermediate reflection shall be the
same as if without any reflection at all the Ray had been twice refracted by
two Parallel surfaces.
And that this is true, not onely in one, but in every Ray that goes to the
constitution of the Primary Iris; nay, in every Ray, that suffers only two
refractions, and one reflection, by the surface of the round body, we shall
presently see most evident, if we repeat the Cartesian Scheme, mentioned in
the tenth Section of the eighth Schem. 6.
Fig. 3. Chapter of his Meteors, where EFKNP in the third Figure is one of the
Rays of the Primary Iris, twice refracted at F and N, and once reflected at K
by the surface of the Water-ball. For, first it is evident, that KF and KN are
equal, because KN being the reflected part of KF they have both the same
inclination on the surface K that is the angles FKT, and NKV made by the
two Rays and the Tangent of K are equal, which is evident by the Laws of
reflection; whence it will follow also, that KN has the same inclination on
the surface N, or the Tangent of it XN that the Ray KF has to the surface F,
or the Tangent of it FY, whence it must necessarily follow, that the
refractions at F and N are equal, that is, KFE and KNP are equal. Now, that
the surface N is by the reflection at K made parallel to the surface at F, is
evident from the principles of reflection; for reflection being nothing but an
inverting of the Rays, if we re-invert the Ray KNP, and make the same
inclinations below the line TKV that it has above, it will be most evident,
that KH the inverse of KN will be the continuation of the line FK, and that
LHI the inverse of OX is parallel to FY. And HM the inverse of NP is
Parallel to EF for the angle KHI is equal to KNO which is equal to KFY,
and the angle KHM is equal to KNP which is equal to KFE which was to be
prov’d.
So that according to the above mentioned Cartesian principles there
should be generated no colour at all in a Ball of Water or Glass by two
refractions and one reflection, which does hold most true indeed, if the

surfaces be plain, as may be experimented with any kind of prisme where
the two refracting surfaces are equally inclin’d to the reflecting; but in this
the Phænomena are quite otherwise.
The cause therefore of the generation of colour must not be what Des
Cartes assigns, namely, a certain rotation of the Globuli ætherei, which are
the particles which he supposes to constitute the Pellucid medium, But
somewhat else, perhaps what we have lately supposed, and shall by and by
further prosecute and explain.
But, First I shall crave leave to propound some other difficulties of his,
notwithstanding exceedingly ingenious Hypothesis, which I plainly confess
to me seem such; and those are,
First, if that light be (as is affirmed, Diopt. cap. 1. §. 8.) not so properly a
motion, as an action or propension to motion, I cannot conceive how the
eye can come to be sensible of the verticity of a Globule, which is generated
in a drop of Rain, perhaps a mile off from it. For that Globule is not carry’d
to the eye according to his formerly recited Principle; and if not so, I cannot
conceive how it can communicate its rotation, or circular motion to the line
of the Globules between the drop and the eye. It cannot be by means of
every ones turning the next before him; for if so, then onely all the Globules
that are in the odd places must be turned the same way with the first,
namely, the 3. 5. 7. 9. 11, &c. but all the Globules interposited between
them in the even places; namely, the 2. 4. 6. 8. 10. &c. must be the quite
contrary, whence, according to the Cartesian Hypothesis, there must be no
distinct colour generated, but a confusion. Next, since the Cartesian Globuli
are suppos’d (Principiorum Philosoph. Part. 3. §. 86.) to be each of them
continually in motion about their centers, I cannot conceive how the eye is
able to distinguish this new generated motion from their former inherent
one, if I may so call that other wherewith they are mov’d or turbinated,
from some other cause than refraction. And thirdly, I cannot conceive how
these motions should not happen sometimes to oppose each other, and then,
in stead of a rotation, there would be nothing but a direct motion generated,
and consequently no colour. And fourthly, I cannot conceive, how by the
Cartesian Hypothesis it is possible to give any plausible reason of the
nature of the Colours generated in the thin laminæ of these our
Microscopical Observations; for in many of these, the refracting and

reflecting surfaces are parallel to each other, and consequently no rotation
can be generated, nor is there any necessity of a shadow or termination of
the bright Rays, such as is suppos’d (Chap. 8. §. 5. Et præterea observavi
umbram quoque, aut limitationem luminis requiri: and Chap. 8. §. 9.) to be
necessary to the generation of any distinct colours; Besides that, here is
oftentimes one colour generated without any of the other appendant ones,
which cannot be by the Cartesian Hypothesis.
There must be therefore some other propriety of refraction that causes
colour. And upon the examination of the thing, I cannot conceive any one
more general, inseparable, and sufficient, than that which I have before
assign’d. That we may therefore see how exactly our Hypothesis agrees also
with the Phænomena of the refracting round body, whether Globe or
Cylinder, we shall next subjoyn our Calculation or Examen of it.
Schem. 6.
Fig. 3.

And to this end, we will calculate any two Rays: as for instance; let EF
be a Ray cutting the Radius CD (divided into 20. parts) in G 16. parts
distant from C, and ef another Ray, which cuts the same Radius in g 17.
parts distant, these will be refracted to K and k, and from thence reflected to
N and n, and from thence refracted toward P and p; therefore the Arch Ff
will be 5.d 5′. The Arch FK 106.d 30′. the Arch fk 101.d 2′. The line FG
6000. and fg 5267. therefore hf. 733. therefore Fc 980, almost. The line FK
16024. and fk 15436. therefore Nd 196. and no 147 almost, the line Nn
1019 the Arch Nn 5.d 51′. therefore the Angle Nno is 34.d 43′. therefore the
Angle Non is 139.d 56′. which is almost 50.d more than a right Angle.
It is evident therefore by this Hypothesis, that at the same time that ef
touches f. EF is arrived at c. And by that time efkn is got to n, EFKN is got
to d and when it touches N, the pulse of the other Ray is got to o. and no
farther, which is very short of the place it should have arriv’d to, to make
the Ray np to cut the orbicular pulse No at right Angles: therefore the
Angle Nop is an acute Angle, but the quite contrary of this will happen, if
17. and 18. be calculated in stead of 16. and 17. both which does most
exactly agree with the Phænomena: For if the Sun, or a Candle (which is
better) be placed about Ee, and the eye about Pp, the Rays EFef at 16. and
17. will paint the side of the luminous object toward np Blue, and towards

NP Red. But the quite contrary will happen when EF is 17. and ef 18. for
then towards NP shall be a Blue, and towards np a Red, exactly according to
the calculation. And there appears the Blue of the Rainbow, where the two
Blue sides of the two Images unite, and there the Red where the two Red
sides unite, that is, where the two Images are just disappearing; which is,
when the Rays EF and NP produc’d till they meet, make an Angle of about
41. and an half; the like union is there of the two Images in the Production
of the Secundary Iris, and the same causes, as upon calculation may appear;
onely with this difference, that it is somewhat more faint, by reason of the
duplicate reflection, which does always weaken the impulse the oftner it is
repeated.
Now, though the second refraction made at Nn be convenient, that is, do
make the Rays glance the more, yet is it not altogether requisite; for it is
plain from the calculation, that the pulse dn is sufficiently oblique to the
Rays KN and kn, as wel as the pulse fc is oblique to the Rays FK & fk. And
therefore if a piece of very fine Paper be held close against Nn and the eye
look on it either through the Ball as from D, or from the other side, as from
B. there shall appear a Rainbow, or colour’d line painted on it with the part
toward X appearing Red, towards O, Blue; the same also shall happen, if the
Paper be placed about Kk, for towards T shall appear a Red, and towards V
a Blue, which does exactly agree with this my Hypothesis, as upon the
calculation of the progress of the pulse will most easily appear.
Nor do these two observations of the colours appearing to the eye about p
differing from what they appear on the Paper at N contradict each other; but
rather confirm and exactly agree with one another, as will be evident to him
that examines the reasons set down by the ingenious. Des Cartes in the 12.
Sect. of the 8. Chapter of his Meteors, where he gives the true reason why
the colours appear of a quite contrary order to the eye, to what they
appear’d on the Paper if the eye be plac’d in steed of the Paper: And as in
the Prisme, so also in the Water-drop, or Globe the Phænomena, and reason
are much the same.
Having therefore shewn that there is such a propriety in the prisme and
water Globule whereby the pulse is made oblique to the progressive, and
that so much the more, by how much greater the refraction is, I shall in the
next place consider, how this conduces to the production of colours, and

what kind of impression it makes upon the bottom of the eye; and to this
end it will be requisite to examine this Hypothesis a little more particularly.
First therefore, if we consider the manner of the progress of the pulse, it
will seem rational to conclude, that that part or end of the pulse which
precedes the other, must necessarily be somwhat more obtunded, or
impeded by the resistance of the transparent medium, than the other part or
end of it which is subsequent, whose way is, as it were, prepared by the
other; especially if the adjacent medium be not in the same manner Schem. 6.
Fig. 4. enlightned or agitated. And therefore (in the fourth Figure of the sixth
Iconism) the Ray AAAHB will have its side HH more deadened by the
resistance of the dark or quiet medium PPP, Whence there will be a kind of
deadness superinduc’d on the side HHH, which will continually increase
from B, and strike deeper and deeper into the Ray by the line BR; Whence
all the parts of the triangle, RBHO will be of a dead Blue colour, and so
much the deeper, by how much the nearer they lie to the line BHH, which is
most deaded or impeded, and so much the more dilute, by how much the
nearer it approaches the line BR. Next on the other side of the Ray AAN,
the end A of the pulse AH will be promoted, or made stronger, having its
passage already prepar’d as ’twere by the other parts preceding, and so its
impression wil be stronger; And because of its obliquity to the Ray, there
will be propagated a kind of faint motion into QQ the adjacent dark or quiet
medium, which faint motion will spread further and further into QQ as the
Ray is propagated further and further from A, namely, as far as the line MA,
whence all the triangle MAN will be ting’d with a Red, and that Red will be
the deeper the nearer it approaches the line MA, and the paler or yellower
the nearer it is the line NA. And if the Ray be continued, so that the lines
AN and BR (which are the bounds of the Red and Blue diluted) do meet and
cross each other, there will be beyond that intersection generated all kinds
of Greens.
Now, these being the proprieties of every single refracted Ray of light, it
will be easie enough to consider what must be the result of very many such
Rays collateral: As if we suppose infinite such Rays interjacent between
AKSB and ANOB, which are the terminating: For in this case the Ray
AKSB will have its Red triangle intire, as lying next to the dark or quiet
medium, but the other side of it BS will have no Blue, because the medium
adjacent to it SBO, is mov’d or enlightned, and consequently that light does

destroy the colour. So likewise will the Ray ANOB lose its Red, because the
adjacent medium is mov’d or enlightned, but the other side of the Ray that
is adjacent to the dark, namely, AHO will preserve its Blue entire, and these
Rays must be so far produc’d as till AN and BR cut each other, before there
will be any Green produc’d. From these Proprieties well consider’d, may be
deduc’d the reasons of all the Phænomena of the prisme, and of the
Globules or drops of Water which conduce to the production of the
Rainbow.
Schem. 6.
Fig. 5.

Next for the impression they make on the Retina, we will further examine
this Hypothesis: Suppose therefore ABCDEF, in the fifth Figure, to
represent the Ball of the eye: on the Cornea of which ABC two Rays
GACH and KCAI (which are the terminating Rays of a luminous body)
falling, are by the refraction thereof collected or converg’d into two points
at the bottom of the eye. Now, because these terminating Rays, and all the
intermediate ones which come from any part of the luminous body, are
suppos’d by some sufficient refraction before they enter the eye, to have
their pulses made oblique to their progression, and consequently each Ray
to have potentially superinduc’d two proprieties, or colours, viz. a Red on
the one side, and a Blue on the other, which notwithstanding are never
actually manifest, but when this or that Ray has the one or the other side of
it bordering on a dark or unmov’d medium, therefore as soon as these Rays
are entred into the eye and so have one side of each of them bordering on a
dark part of the humours of the eye, they will each of them actually exhibit
some colour; therefore ADC the production of GACH will exhibit a Blue,
because the side CD is adjacent to the dark medium CQDC, but nothing of
a Red, because its side AD is adjacent to the enlightned medium ADFA:
And all the Rays that from the points of the luminous body are collected on
the parts of the Retina between D and F shall have their Blue so much the
more diluted by how much the farther these points of collection are distant
from D towards F; and the Ray AFC the production of KCAI, will exhibit a
Red, because the side AF is adjacent to the dark or quiet medium of the eye
APFA, but nothing of a Blue, because its side CF is adjacent to the
enlightned medium CFDC, and all the Rays from the intermediate parts of
the luminous body that are collected between F and D shall have their Red

so much the more diluted, by how much the farther they are distant from F
towards D.
Now, because by the refraction in the Cornea, and some other parts of the
eye, the sides of each Ray, which before were almost parallel, are made to
converge and meet in a point at the bottom of the eye, therefore that side of
the pulse which preceded before these refractions, shall first touch the
Retina, and the other side last. And therefore according as this or that side,
or end of the pulse shall be impeded, accordingly will the impressions on
the Retina be varied; therefore by the Ray GACH refracted by the Cornea
to D there shall be on that point a stroke or impression confus’d, whose
weakest end, namely, that by the line CD shall precede, and the stronger,
namely, that by the line AD shall follow. And by the Ray KCAI refracted to
F, there shall be on that part a confus’d stroke or impression, whose
strongest part, namely, that by the line CF shal precede, and whose weakest
or impeded, namely, that by the line AF shall follow, and all the
intermediate points between F and D will receive impressions from the
converg’d Rays so much the more like the impressions on F and D by how
much the nearer they approach that or this.
From the consideration of the proprieties of which impressions, we may
collect these short definitions of Colours: That Blue is an impression on the
Retina of an oblique and confus’d pulse of light, whose weakest part
precedes, and whose strongest follows. And, that Red is an impression on
the Retina of an oblique and confus’d pulse of light, whose strongest part
precedes, and whose weakest follows.
Which proprieties, as they have been already manifested, in the Prisme
and falling drops of Rain, to be the causes of the colours there generated,
may be easily found to be the efficients also of the colours appearing in thin
laminated transparent bodies; for the explication of which, all this has been
premised.
And that this is so, a little closer examination of the Phænomena and the
Figure of the body, by this Hypothesis will make evident.
For first (as we have already observed) the laminated body must be of a
determinate thickness, that is, it must not be thinner then such a determinate
quantity; for I have always observ’d, that neer the edges of those which are

exceeding thin, the colours disappear, and the part grows white; nor must it
be thicker then another determinate quantity; for I have likewise observ’d,
that beyond such a thickness, no colours appear’d, but the Plate looked
white, between which two determinate thicknesses were all the colour’d
Rings; of which in some substances I have found ten or twelve, in others
not half so many, which I suppose depends much upon the transparency of
the laminated body. Thus though the consecutions are the same in the scum
or the skin on the top of metals; yet in those consecutions in the same
colour is not so often repeated as in the consecutions in thin Glass, or in
Sope-water, or any other more transparent and glutinous liquor; for in these
I have observ’d, Red, Yellow, Green, Blue, Purple; Red, Yellow, Green,
Blue, Purple; Red, Yellow, Green, Blue, Purple; Red, Yellow, &c. to succeed
each other, ten or twelve times, but in the other more opacous bodies the
consecutions will not be half so many.
And therefore secondly, the laminated body must be transparent, and this
I argue from this, that I have not been able to produce any colour at all with
an opacous body, though never so thin. And this I have often try’d, by
pressing small Globule of Mercury between two smooth Plates of Glass,
whereby I have reduc’d that body to a much greater thinness then was
requisite to exhibit the colours with a transparent body.
Thirdly, there must be a considerable reflecting body adjacent to the
under or further side of the lamina or plate: for this I always found, that the
greater that reflection was, the more vivid were the appearing colours.
From which Observations, is most evident, that the reflection from the
under or further side of the body is the principal cause of the production of
these colours; which, that it is so, and how it conduces to that effect, I shall
further explain in the following Figure, which is here described of a very
great thickness, as if it had been view’d through the Microscope; and ’tis
indeed much thicker than any Microscope (I have yet us’d) has been able to
shew me those colour’d plates of Glass, or Muscovie-glass, which I have
not without much trouble view’d with it, for though I have endeavoured to
magnifie them as much as the Glasses were capable of, yet are they so
exceeding thin, that I have not hitherto been able positively to determine
their thickness. This Figure therefore I here represent, is wholy
Hypothetical.

Schem. 6.
Fig. 6.

Let ABCDHFE in the sixth Figure be a frustum of Muscovy-glass,
thinner toward the end AE, and thicker towards DF. Let us first suppose the
Ray aghb coming from the Sun, of some remote luminous object to fall
obliquely on the thinner plate BAE, part therefore is reflected back by cghd,
the first Superficies; whereby the perpendicular pulse ab is after reflexion
propagated by cd, cd, equally remote from each other with ab, ab, so that
ag + gc, or bh + hd are either of them equal to aa, as is also cc, but the body
BAE being transparent, a part of the light of this Ray is refracted in the
surface AB, and propagated by gikh to the surface EF, whence it is reflected
and refracted again by the surface AB. So that after two refractions and one
reflection, there is propagated a kind of fainter Ray emnf, whose pulse is not
only weaker by reason of the two refractions in the surface AB, but by
reason of the time spent in passing and repassing between the two surfaces
AB and EF, ef which is this fainter or weaker pulse comes behind the pulse
cd; so that hereby (the surfaces AB, and EF being so neer together, that the
eye cannot discriminate them from one) this confus’d or duplicated pulse,
whose strongest part precedes, and whose weakest follows, does produce on
the Retina, (or the optick nerve that covers the bottom of the eye) the
sensation of a Yellow.
And secondly, this Yellow will appear so much the deeper, by how much
the further back towards the middle between cd and cd the spurious pulse ef
is remov’d, as in 2 where the surface BC being further remov’d from EF,
the weaker pulse ef will be nearer to the middle, and will make an
impression on the eye of a Red.
But thirdly, if the two reflecting surfaces be yet further remov’d asunder
(as in 3 CD and EF are) then will the weaker pulse be so farr behind, that it
will be more then half the distance between cd and cd. And in this case it
will rather seem to precede the following stronger pulse, then to follow the
preceding one, and consequently a Blue will be generated. And when the
weaker pulse is just in the middle between two strong ones, then is a deep
and lovely Purple generated; but when the weaker pulse ef is very neer to
cd, then is there generated a Green, which will be bluer, or yellower,
according as the approximate weak pulse does precede or follow the
stronger.

Now fourthly, if the thicker Plate chance to be cleft into two thinner
Plates, as CDFE is divided into two Plates by the surface GH then from the
composition arising from the three reflections in the surfaces CD, GH, and
EF, there will be generated several compounded or mixt colours, which will
be very differing, according as the proportion between the thicknesses of
those two divided Plates CDHG, and GHFE are varied.
And fifthly, if these surfaces CD and FE are further remov’d asunder, the
weaker pulse will yet lagg behind much further, and not onely be coincident
with the second, cd, but lagg behind that also, and that so much the more,
by how much the thicker the Plate be; so that by degrees it will be
coincident with the third cd backward also, and by degrees, as the Plate
grows thicker with a fourth, and so onward to a fifth, sixth, seventh, or
eighth; so that if there be a thin transparent body, that from the greatest
thinness requisite to produce colours, does, in the manner of a Wedge, by
degrees grow to the greatest thickness that a Plate can be of, to exhibit a
colour by the reflection of Light from such a body, there shall be generated
several consecutions of colours, whose order from the thin end towards the
thick, shall be Yellow, Red, Purple, Blue, Green; Yellow, Red, Purple, Blue,
Green; Yellow, Red, Purple, Blue, Green; Yellow, &c. and these so often
repeated, as the weaker pulse does lose paces with its Primary, or first
pulse, and is coincident with a second, third, fourth, fifth, sixth, &c. pulse
behind the first. And this, as it is coincident, or follows from the first
Hypothesis I took of colours, so upon experiment have I found it in
multitudes of instances that seem to prove it. One thing which seems of the
greatest concern in this Hypothesis, is to determine the greatest or least
thickness requisite for these effects, which, though I have not been wanting
in attempting, yet so exceeding thin are these coloured Plates, and so
imperfect our Microscope, that I have not been hitherto successfull, though
if my endeavours shall answer my expectations, I shall hope to gratifie the
curious Reader with some things more remov’d beyond our reach hitherto.
Thus have I, with as much brevity as I was able, endeavoured to explicate
(Hypothetically at least) the causes of the Phænomena I formerly recited, on
the consideration of which I have been the more particular.
First, because I think these I have newly given are capable of explicating
all the Phænomena of colours, not onely of those appearing in the Prisme,

Water-drop, or Rainbow, and in laminated or plated bodies, but of all that
are in the world, whether they be fluid or solid bodies, whether in thick or
thin, whether transparent, or seemingly opacous, as I shall in the next
Observation further endeavour to shew. And secondly, because this being
one of the two ornaments of all bodies discoverable by the sight, whether
looked on with, or without a Microscope, it seem’d to deserve (somewhere
in this Tract, which contains a description of the Figure and Colour of some
minute bodies) to be somewhat the more intimately enquir’d into.

Observ. X. Of Metalline, and other real Colours.
Having in the former Discourse, from the Fundamental cause of Colour,
made it probable, that there are but two Colours, and shewn, that the
Phantasm of Colour is caus’d by the sensation of the oblique or uneven
pulse of Light which is capable of no more varieties than two that arise
from the two sides of the oblique pulse, though each of those be capable of
infinite gradations or degrees (each of them beginning from White, and
ending the one in the deepest Scarlet or Yellow, the other in the deepest
Blue) I shall in this Section set down some Observations which I have made
of other colours, such as Metalline powders tinging or colour’d bodies and
several kinds of tinctures or ting’d liquors, all which, together with those I
treated of in the former Observation will, I suppose, comprise the several
subjects in which colour is observ’d to be inherent, and the several manners
by which it inheres, or is apparent in them. And here I shall endeavour to
shew by what composition all kind of compound colours are made, and how
there is no colour in the world but may be made from the various degrees of
these two colours, together with the intermixtures of Black and White.
And this being so, as I shall anon shew, it seems an evident argument to
me, that all colours whatsoever, whether in fluid or solid, whether in very
transparent or seemingly opacous, have the same efficient cause, to wit,
some kind of refraction whereby the Rays that proceed from such bodies,
have their pulse obliquated or confus’d in the manner I explicated in the
former Section; that is, a Red is caus’d by a duplicated or confus’d pulse,
whose strongest pulse precedes, and a weaker follows: and a Blue is caus’d
by a confus’d pulse, where the weaker pulse precedes, and the stronger
follows. And according as these are, more or less, or variously mixt and
compounded, so are the sensations, and consequently the phantasms of
colours diversified.
To proceed therefore; I suppose, that all transparent colour’d bodies,
whether fluid or solid, do consist at least of two parts, or two kinds of
substances, the one of a substance of a somewhat differing refraction from
the other. That one of these substances which may be call’d the tinging

substance, does consist of distinct parts, or particles of a determinate
bigness which are disseminated, or dispers’d all over the other: That these
particles, if the body be equally and uniformly colour’d, are evenly rang’d
and dispers’d over the other contiguous body; That where the body is
deepest ting’d, there these particles are rang’d thickest, and where ’tis but
faintly ting’d, they are rang’d much thinner, but uniformly. That by the
mixture of another body that unites with either of these, which has a
differing refraction from either of the other, quite differing effects will be
produc’d, that is, the consecutions of the confus’d pulses will be much of
another kind, and consequently produce other sensations and phantasms of
colours, and from a Red may turn to a Blue, or from a Blue to a Red, &c.
Now, that this may be the better understood, I shall endeavour to Schem. 6.
Fig. 7. explain my meaning a little more sensible by a Scheme: Suppose we
therefore in the seventh Figure of the sixth Scheme, that ABCD represents a
Vessel holding a ting’d liquor, let IIIII, &c. be the clear liquor, and let the
tinging body that is mixt with it be EE, &c. FF, &c. GG, &c. HH, &c.
whose particles (whether round, or some other determinate Figure is little to
our purpose) are first of a determinate and equal bulk. Next, they are rang’d
into the form of Quincunx, or Equilaterotriangular order, which that
probably they are so, and why they are so, I shall elsewhere endeavour to
shew. Thirdly, they are of such a nature, as does either more easily or more
difficultly transmit the Rays of light then the liquor; if more easily, a Blue is
generated, and if more difficultly, a Red or Scarlet.
And first, let us suppose the tinging particles to be of a substance that
does more impede the Rays of light, we shall find that the pulse or wave of
light mov’d from AD to BC, will proceed on, through the containing
medium by the pulses or waves KK, LL, MM, NN, OO; but because several
of these Rays that go to the constitution of these pulses will be slugged or
stopped by the tinging particles E, F, G, H; therefore there shall be
secundary and weak pulse that shall follow the Ray, namely PP which will
be the weaker: first, because it has suffer’d many refractions in the
impeding body; next, for that the Rays will be a little dispers’d or confus’d
by reason of the refraction in each of the particles, whether round or
angular; and this will be more evident, if we a little more closely examine
any one particular tinging Globule.

Schem. 6.
Fig. 8.

Suppose we therefore AB in the eighth Figure of the sixth Scheme, to
represent a tinging Globule or particle which has a greater refraction than
the liquor in which it is contain’d: Let CD be a part of the pulse of light
which is propagated through the containing medium; this pulse will be a
little stopt or impeded by the Globule, and so by that time the pulse is past
to EF that part of it which has been impeded by passing through the
Globule, will get but to LM, and so that pulse which has been propagated
through the Globule, to wit, LM, NO, PQ, will always come behind the
pulses EF, GH, IK, &c.
Next, by reason of the greater impediment in AB, and its Globular
Figure, the Rays that pass through it will be dispers’d, and very much
scatter’d. Whence CA and DB which before went direct and parallel, will
after the refraction in AB, diverge and spread by AP, and BQ; so that as the
Rays do meet with more and more of these tinging particles in their way, by
so much the more will the pulse of light further lagg behind the clearer
pulse, or that which has fewer refractions, and thence the deeper will the
colour be, and the fainter the light that is trajected through it; for not onely
many Rays are reflected from the surfaces of AB, but those Rays that get
through it are very much disordered.
By this Hypothesis there is no one experiment of colour that I have yet
met with, but may be, I conceive, very rationably solv’d, and perhaps, had I
time to examine several particulars requisite to the demonstration of it, I
might prove it more than probable, for all the experiments about the
changes and mixings of colours related in the Treatise of Colours, published
by the Incomparable Mr. Boyle, and multitudes of others which I have
observ’d, do so easily and naturally flow from those principles, that I am
very apt to think it probable, that they own their production to no other
secundary cause: As to instance in two or three experiments. In the
twentieth Experiment, this Noble Authour has shewn that the deep bluish
purple-colour of Violets, may be turn’d into a Green, by Alcalizate Salts,
and to a Red by acid; that is, a Purple consists of two colours, a deep Red,
and a deep Blue; when the Blue is diluted, or altered, or destroy’d by acid
Salts, the Red becomes predominant, but when the Red is diluted by

Alcalizate, and the Blue heightned, there is generated a Green; for of a Red
diluted, is made a Yellow, and Yellow and Blue make a Green.
Now, because the spurious pulses which cause a Red and a Blue, do the
one follow the clear pulse, and the other precede it, it usually follows, that
those Saline refracting bodies which do dilute the colour of the one, do
deepen that of the other. And this will be made manifest by almost all kinds
of Purples, and many sorts of Greens, both these colours consisting of mixt
colours; for if we suppose A and A in the ninth Figure, to represent two
pulses of clear light, which follow each other at a convenient distance, AA,
each of which has a spurious pulse preceding it, as BB, which makes a
Blue, and another following it, as CC, which makes a Red, the one caus’d
by tinging particles that have a greater refraction, the other by others that
have a less refracting quality then the liquor or Menstruum in which these
are dissolv’d, whatsoever liquor does so alter the refraction of the one,
without altering that of the other part of the ting’d liquor, must needs very
much alter the colour of the liquor; for if the refraction of the dissolvent be
increas’d, and the refraction of the tinging particles not altered, then will the
preceding spurious pulse be shortned or stopt, and not out-run the clear
pulse so much; so that BB will become EE, and the Blue be diluted,
whereas the other spurious pulse which follows will be made to lagg much
more, and be further behind AA than before, and CC will become ff, and so
the Yellow or Red will be heightned.
A Saline liquor therefore, mixt with another ting’d liquor, may alter the
colour of it several ways, either by altering the refraction of the liquor in
which the colour swims: or secondly by varying the refraction of the
coloured particles, by uniting more intimately either with some particular
corpuscles of the tinging body, or with all of them, according as it has a
congruity to some more especially, or to all alike: or thirdly, by uniting and
interweaving it self with some other body that is already joyn’d with the
tinging particles, with which substance it may have a congruity, though it
have very little with the particles themselves: or fourthly, it may alter the
colour of a ting’d liquor by dis-joyning certain particles which were before
united with the tinging particles, which though they were somewhat
congruous to these particles, have yet a greater congruity with the newly
infus’d Saline menstruum. It may likewise alter the colour by further
dissolving the tinging substance into smaller and smaller particles, and so

diluting the colour; or by uniting several particles together as in
precipitations, and so deepning it, and some such other ways, which many
experiments and comparisons of differing trials together, might easily
inform one of.
From these Principles applied, may be made out all the varieties of
colours observable, either in liquors, or any other ting’d bodies, with great
ease, and I hope intelligible enough, there being nothing in the notion of
colour, or in the suppos’d production, but is very conceivable, and may be
possible.
The greatest difficulty that I find against this Hypothesis, is, that there
seem to be more distinct colours then two, that is, then Yellow and Blue.
This Objection is grounded on this reason, that there are several Reds,
which diluted, make not a Saffron or pale Yellow, and therefore Red, or
Scarlet seems to be a third colour distinct from a deep degree of Yellow.
To which I answer, that Saffron affords us a deep Scarlet tincture, which
may be diluted into as pale a Yellow as any, either by making a weak
solution of the Saffron, by infusing a small parcel of it into a great quantity
of liquor, as in spirit of Wine, or else by looking through a very thin
quantity of the tincture, and which may be heightn’d into the loveliest
Scarlet, by looking through a very thick body of this tincture, or through a
thinner parcel of it, which is highly impregnated with the tinging body, by
having had a greater quantity of the Saffron dissolv’d in a smaller parcel of
the liquor.
Now, though there may be some particles of other tinging bodies that
give a lovely Scarlet also, which though diluted never so much with liquor,
or looked on through never so thin a parcel of ting’d liquor, will not yet
afford a pale Yellow, but onely a kind of faint Red; yet this is no argument
but that those ting’d particles may have in them the faintest degree of
Yellow, though we may be unable to make them exhibit it; For that power
of being diluted depending upon the divisibility of the ting’d body, if I am
unable to make the tinging particles so thin as to exhibit that colour, it does
not therefore follow, that the thing is impossible to be done; now, the
tinging particles of some bodies are of such a nature, that unless there be
found some way of comminuting them into less bulks then the liquor does

dissolve them into, all the Rays that pass through them must necessarily
receive a tincture so deep, as their appropriate refractions and bulks
compar’d with the proprieties of the dissolving liquor must necessarily
dispose them to empress, which may perhaps be a pretty deep Yellow, or
pale Red.
And that this is not gratis dictum, I shall add one instance of this kind,
wherein the thing is most manifest.
If you take Blue Smalt, you shall find, that to afford the deepest Blue,
which cæteris paribus has the greatest particles or sands; and if you further
divide, or grind those particles on a Grindstone, or porphyry stone, you may
by comminuting the sands of it, dilute the Blue into as pale a one as you
please, which you cannot do by laying the colour thin; for wheresoever any
single particle is, it exhibits as deep a Blue as the whole mass. Now, there
are other Blues, which though never so much ground, will not be diluted by
grinding, because consisting of very small particles, very deeply ting’d,
they cannot by grinding be actually separated into smaller particles then the
operation of the fire, or some other dissolving menstruum, reduc’d them to
already.
Thus all kind of Metalline colours, whether precipitated, sublim’d,
calcin’d, or otherwise prepar’d, are hardly chang’d by grinding, as ultra
marine is not more diluted; nor is Vermilion or Red-lead made of a more
faint colour by grinding; for the smallest particles of these which I have
view’d with my greatest Magnifying-Glass, if they be well enlightned,
appear very deeply ting’d with their peculiar colours; nor, though I have
magnified and enlightned the particles exceedingly, could I in many of
them, perceive them to be transparent, or to be whole particles, but the
smallest specks that I could find among well ground Vermilion and Red-
lead, seem’d to be a Red mass, compounded of a multitude of less and less
motes, which sticking together, compos’d a bulk, not one thousand
thousandth part of the smallest visible sand or mote.
And this I find generally in most Metalline colours, that though they
consist of parts so exceedingly small, yet are they very deeply ting’d, they
being so ponderous, and having such a multitude of terrestrial particles
throng’d into a little room; so that ’tis difficult to find any particle

transparent or resembling a pretious stone, though not impossible; for I
have observ’d divers such shining and resplendent colours intermixt with
the particles of Cinnaber, both natural and artificial, before it hath been
ground and broken or flaw’d into Vermilion: As I have also in Orpiment,
Red-lead, and Bise, which makes me suppose, that those metalline colours
are by grinding, not onely broken and separated actually into smaller pieces,
but that they are also flaw’d and brused, whence they, for the most part,
become opacous, like flaw’d Crystal or Glass, &c. But for Smalts and
verditures, I have been able with a Microscope to perceive their particles
very many of them transparent.
Now, that the others also may be transparent, though they do not appear
so to the Microscope, may be made probable by this Experiment: that if you
take ammel that is almost opacous, and grind it very well on a Porphyry, or
Serpentine, the small particles will by reason of their flaws, appear perfectly
opacous; and that ’tis the flaws that produce this opacousness, may be
argued from this, that particles of the same Ammel much thicker if unflaw’d
will appear somewhat transparent even to the eye; and from this also, that
the most transparent and clear Crystal, if heated in the fire, and then
suddenly quenched, so that it be all over flaw’d, will appear opacous and
white.
And that the particles of Metalline colours are transparent, may be argued
yet further from this, that the Crystals, or Vitriols of all Metals, are
transparent, which since they consist of metalline as well as saline particles,
those metalline ones must be transparent, which is yet further confirm’d
from this, that they have for the most part, appropriate colours; so the
vitriol of Gold is Yellow; of Copper, Blue, and sometimes Green; of Iron,
green; of Tinn and Lead, a pale White; of Silver, a pale Blue, &.
And next, the Solution of all Metals into menstruums are much the same
with the Vitriols, or Crystals. It seems therefore very probable, that those
colours which are made by the precipitation of those particles out of the
menstruums by transparent precipitating liquors should be transparent also.
Thus Gold precipitates with oyl of Tartar, or spirit of Urine into a brown
Yellow, Copper with spirit of Urine into a Mucous blue, which retains its
transparency. A solution of sublimate (as the same Illustrious Authour I
lately mention’d shews in his 40. Experiment) precipitates with oyl of

Tartar per deliquium, into an Orange colour’d precipitate; nor is it less
probable, that the calcination of those Vitriols by the fire, should have their
particles transparent: Thus Saccarum Saturni, or the Vitriol of Lead by
calcination becomes a deep Orange-colour’d minium, which is a kind of
precipitation by some Salt which proceeds from the fire; common Vitriol
calcin’d, yields a deep Brown Red, &c.
A third Argument, that the particles of Metals are transparent, is, that
being calcin’d, and melted with Glass, they tinge the Glass with transparent
colours. Thus the Calx of Silver tinges the Glass on which it is anneal’d
with a lovely Yellow, or Gold colour, &c.
And that the parts of Metals are transparent, may be farther argued from
the transparency of Leaf-gold, which held against the light, both to the
naked eye, and the Microscope, exhibits a deep Green. And though I have
never seen the other Metals laminated so thin, that I was able to perceive
them transparent, yet, for Copper and Brass, if we had the same
conveniency for laminating them, as we have for Gold, we might, perhaps,
through such plates or leaves, find very differing degrees of Blue, or Green;
for it seems very probable, that those Rays that rebound from them ting’d,
with a deep Yellow, or pale Red, as from Copper, or with a pale Yellow, as
from Brass, have past through them; for I cannot conceive how by
reflection alone those Rays can receive a tincture, taking any Hypothesis
extant.
So that we see there may a sufficient reason be drawn from these
instances, why those colours which we are unable to dilute to the palest
Yellow, or Blue, or Green, are not therefore to be concluded not to be a
deeper degree of them; for supposing we had a great company of small
Globular essence Bottles, or round Glass bubbles, about the bigness of a
Walnut, fill’d each of them with a very deep mixture of Saffron, and that
every one of them did appear of a deep Scarlet colour, and all of them
together did exhibit at a distance, a deep dy’d Scarlet body. It does not
follow, because after we have come nearer to this congeries, or mass, and
divided it into its parts, and examining each of its parts severally or apart,
we find them to have much the same colour with the whole mats; it does
not, I say, therefore follow, that if we could break those Globules smaller, or
any other ways come to see a smaller or thinner parcel of the ting’d liquor

that fill’d those bubbles, that that ting’d liquor must always appear Red, or
of a Scarlet hue, since if Experiment be made, the quite contrary will ensue;
for it is capable of being diluted into the palest Yellow.
Now, that I might avoid all the Objections of this kind, by exhibiting an
Experiment that might by ocular proof convince those whom other reasons
would not prevail with, I provided me a Prismatical Glass, Schem. 6.
Fig. 10. made hollow, just in the form of a Wedge, such as is represented in
the tenth Figure of the sixth Scheme. The two parallelogram sides ABCD,
ABEF, which met at a point, were made of the clearest Looking-glass plates
well ground and polish’d that I could get; these were joyn’d with hard
cement to the triangular sides, BCE, ADF, which were of Wood; the
Parallelogram base BCEF, likewise was of Wood joyn’d on to the rest with
hard cement, and the whole Prismatical Box was exactly stopt every where,
but onely a little hole near the base was left, whereby the Vessel could be
fill’d with any liquor, or emptied again at pleasure.
One of these Boxes (for I had two of them) I fill’d with a pretty deep
tincture of Aloes, drawn onely with fair Water, and then stopt the hole with
a piece of Wax, then, by holding this Wedge against the Light, and looking
through it, it was obvious enough to see the tincture of the liquor near the
edge of the Wedge where it was but very thin, to be a pale but well colour’d
Yellow, and further and further from the edge, as the liquor grew thicker
and thicker, this tincture appear’d deeper and deeper, so that near the blunt
end, which was seven Inches from the edge and three Inches and an half
thick; it was of a deep and well colour’d Red. Now, the clearer and purer
this tincture be, the more lovely will the deep Scarlet be, and the fouler the
tincture be, the more dirty will the Red appear; so that some dirty tinctures
have afforded their deepest Red much of the colour of burnt Oker or
Spanish brown; others as lovely a colour as Vermilion, and some much
brighter; but several others, according as the tinctures were worse or more
foul, exhibited various kinds of Reds, of very differing degrees.
The other of these Wedges, I fill’d with a most lovely tincture of Copper,
drawn from the filings of it, with spirit of Urine, and this Wedge held as the
former against the Light, afforded all manner of Blues, from the faintest to
the deepest, so that I was in good hope by these two, to have produc’d all
the varieties of colours imaginable; for I thought by this means to have been

able by placing the two Parallelogram sides together, and the edges
contrary ways, to have so mov’d them to and fro one by another, as by
looking through them in several places, and through several thicknesses, I
should have compounded, and consequently have seen all those colours,
which by other like compositions of colours would have ensued.
But insteed of meeting with what I look’d for, I met with somewhat more
admirable; and that was, that I found my self utterly unable to see through
them when placed both together, though they were transparent enough when
asunder; and though I could see through twice the thickness, when both of
them were fill’d with the same colour’d liquors, whether both with the
Yellow, or both with the Blue, yet when one was fill’d with the Yellow, the
other with the Blue, and both looked through, they both appear’d dark,
onely when the parts near the tops were look’d through, they exhibited
Greens, and those of very great variety, as I expected, but the Purples and
other colours, I could not by any means make, whether I endeavour’d to
look through them both against the Sun, or whether I plac’d them against
the hole of a darkned room.
But notwithstanding this mis-ghessing, I proceeded on with my trial in a
dark room, and having two holes near one another, I was able, by placing
my Wedges against them, to mix the ting’d Rays that past through them,
and fell on a sheet of white Paper held at a convenient distance from them
as I pleas’d; so that I could make the Paper appear of what colour I would,
by varying the thicknesses of the Wedges, and consequently the tincture of
the Rays that past through the two holes, and sometimes also by varying the
Paper, that is, insteed of a white Paper, holding a gray, or a black piece of
Paper.
Whence I experimentally found what I had before imagin’d, that all the
varieties of colours imaginable are produc’d from several degrees of these
two colours, namely, Yellow and Blue, or the mixture of them with light and
darkness, that is, white and black. And all those almost infinite varieties
which Limners and Painters are able to make by compounding those several
colours they lay on their Shels or Palads, are nothing else, but some
compositum, made up of some one or more, or all of these four.

Now, whereas it may here again be objected, that neither can the Reds be
made out of the Yellows, added together, or laid on in greater or less
quantity, nor can the Yellows be made out of the Reds though laid never so
thin; and as for the addition of White or Black, they do nothing but either
whiten or darken the colours to which they are added, and not at all make
them of any other kind of colour: as for instance, Vermilion, by being
temper’d with White Lead, does not at all grow more Yellow, but onely
there is made a whiter kind of Red. Nor does Yellow Oker, though laid
never so thick, produce the colour of Vermilion, nor though it be temper’d
with Black, does it at all make a Red; nay, though it be temper’d with
White, it will not afford a fainter kind of Yellow, such as masticut, but onely
a whiten’d Yellow; nor will the Blues be diluted or deepned after the
manner I speak of, as Indico will never afford so fine a Blue as Ultramarine
or Bise; nor will it, temper’d with Vermilion, ever afford a Green, though
each of them be never so much temper’d with white.
To which I answer, that there is a great difference between diluting a
colour and whitening of it; for diluting a colour, is to make the colour’d
parts more thin, so that the ting’d light, which is made by trajecting those
ting’d bodies, does not receive so deep a tincture; but whitening a colour is
onely an intermixing of many clear reflections of light among the same
ting’d parts; deepning also, and darkning or blacking a colour, are very
different; for deepning a colour, is to make the light pass through a greater
quantity of the same tinging body; and darkning or blacking a colour, is
onely interposing a multitude of dark or black spots among the same ting’d
parts, or placing the colour in a more faint light.
First therefore, as to the former of these operations, that is, diluting and
deepning, most of the colours us’d by the Limners and Painters are
incapable of, to wit, Vermilion and Red-lead, and Oker, because the ting’d
parts are so exceeding small, that the most curious Grindstones we have, are
not able to separate them into parts actually divided so small as the ting’d
particles are; for looking on the most curiously ground Vermilion, and Oker,
and Red-lead, I could perceive that even those small corpuscles of the
bodies they left were compounded of many pieces, that is, they seem’d to
be small pieces compounded of a multitude of lesser ting’d parts: each
piece seeming almost like a piece of Red Glass, or ting’d Crystal all flaw’d;
so that unless the Grindstone could actually divide them into smaller pieces

then those flaw’d particles were, which compounded that ting’d mote I
could see with my Microscope, it would be impossible to dilute the colour
by grinding, which, because the finest we have will not reach to do in
Vermilion or Oker, therefore they cannot at all, or very hardly be diluted.
Other colours indeed, whose ting’d particles are such as may be made
smaller, by grinding their colour, may be diluted. Thus several of the Blues
may be diluted, as Smalt and Bise; and Masticut, which is Yellow, may be
made more faint: And even Vermilion it self may, by too much grinding, be
brought to the colour of Red-lead, which is but an Orange colour, which is
confest by all to be very much upon the Yellow. Now, though perhaps
somewhat of this diluting of Vermilion by overmuch grinding may be
attributed to the Grindstone, or muller, for that some of their parts may be
worn off and mixt with the colour, yet there seems not very much, for I
have done it on a Serpentine-stone with a muller made of a Pebble, and yet
observ’d the same effect follow.
And secondly, as to the other of these operations on colours, that is, the
deepning of them, Limners and Painters colours are for the most part also
uncapable. For they being for the most part opacous; and that opacousness,
as I said before, proceeding from the particles, being very much flaw’d,
unless we were able to joyn and reunite those flaw’d particles again into
one piece, we shall not be able to deepen the colour, which since we are
unable to do with most of the colours which are by Painters accounted
opacous, we are therefore unable to deepen them by adding more of the
same kind.
But because all those opacous colours have two kinds of beams or Rays
reflected from them, that is, Rays unting’d, which are onely reflected from
the outward surface, without at all penetrating of the body, and ting’d Rays
which are reflected from the inward surfaces or flaws after they have
suffer’d a two-fold refraction; and because that transparent liquors mixt
with such corpuscles, do, for the most part, take off the former kind of
reflection; therefore these colours mixt with Water or Oyl, appear much
deeper than when dry, for most part of that white reflection from the
outward surface is remov’d. Nay, some of these colours are very much
deepned by the mixture with some transparent liquor, and that because they

may perhaps get between those two flaws, and so consequently joyn two or
more of those flaw’d pieces together; but this happens but in a very few.
Now, to shew that all this is not gratis dictum, I shall set down some
Experiments which do manifest these things to be probable and likely,
which I have here deliver’d.
For, first, if you take any ting’d liquor whatsoever, especially if it be
pretty deeply ting’d, and by any means work it into a froth, the congeries of
that froth shall seem an opacous body, and appear of the same colour, but
much whiter than that of the liquor out of which it is made. For the
abundance of reflections of the Rays against those surfaces of the bubbles
of which the froth consists, does so often rebound the Rays backwards, that
little or no light can pass through, and consequently the froth appears
opacous.
Again, if to any of these ting’d liquors that will endure the boiling there
be added a small quantity of fine flower (the parts of which through the
Microscope are plainly enough to be perceiv’d to consist of transparent
corpuscles) and suffer’d to boyl till it thicken the liquor, the mass of the
liquor will appear opacous, and ting’d with the same colour, but very much
whiten’d.
Thus, if you take a piece of transparent Glass that is well colour’d, and
by heating it, and then quenching it in Water, you flaw it all over, it will
become opacous, and will exhibit the same colour with which the piece is
ting’d, but fainter and whiter.
Or, if you take a Pipe of this transparent Glass, and in the flame of a
Lamp melt it, and then blow it into very thin bubbles, then break those
bubbles, and collect a good parcel of those laminæ together in a Paper, you
shall find that a small thickness of those Plates will constitute an opacous
body, and that you may see through the mass of Glass before it be thus
laminated, above four times the thickness: And besides, they will now
afford a colour by reflection as other opacous (as they are call’d) colours
will, but much fainter and whiter than that of the Lump or Pipe out of which
they were made.

Thus also, if you take Putty, and melt it with any transparent colour’d
Glass, it will make it become an opacous colour’d lump, and to yield a
paler and whiter colour than the lump by reflection.
The same thing may be done by a preparation of Antimony, as has been
shewn by the Learned Physician, Dr. C.M. in his Excellent Observations
and Notes on Nery’s Art of Glass; and by this means all transparent colours
become opacous, or ammels. And though by being ground they lose very
much of their colour, growing much whiter by reason of the multitude of
single reflections from their outward surface, as I shew’d afore, yet the fire
that in the nealing or melting re-unites them, and so renews those spurious
reflections, removes also those whitenings of the colour that proceed from
them.
As for the other colours which Painters use, which are transparent, and
us’d to varnish over all other paintings, ’tis well enough known that the
laying on of them thinner or thicker, does very much dilute or deepen their
colour.
Painters Colours therefore consisting most of them of solid particles, so
small that they cannot be either re-united into thicker particles by any Art
yet known, and consequently cannot be deepned; or divided into particles
so small as the flaw’d particles that exhibit that colour, much less into
smaller, and consequently cannot be diluted; It is necessary that they which
are to imitate all kinds of colours, should have as many degrees of each
colour as can be procur’d.
And to this purpose, both Limners and Painters have a very great variety
both of Yellows and Blues, besides several other colour’d bodies that
exhibit very compounded colours, such as Greens and Purples; and others
that are compounded of several degrees of Yellow, or several degrees of
Blue, sometimes unmixt, and sometimes compounded with several other
colour’d bodies.
The Yellows, from the palest to the deepest Red or Scarlet, which has no
intermixture of Blue, are pale and deep Masticut, Orpament, English Oker,
brown Oker, Red-Lead, and Vermilion, burnt English Oker, and burnt brown
Oker, which last have a mixture of dark or dirty parts with them, &c.

Their Blues are several kinds of Smalts, and Verditures, and Bise, and
Ultramarine, and Indico, which last has many dirty or dark parts intermixt
with it.
Their compounded colour’d bodies, as Pink, and Verdigrese, which are
Greens, the one a Popingay, the other a Sea-green; then Lac, which is a
very lovely Purple.
To which may be added their Black and White, which they also usually
call Colours, of each of which they have several kinds, such as Bone Black,
made of Ivory burnt in a close Vessel, and Blue Black, made of the small
coal of Willow, or some other Wood; and Cullens earth, which is a kind of
brown Black, &c. Their usual Whites are either artificial or natural White
Lead, the last of which is the best they yet have, and with the mixing and
tempering these colours together, are they able to make an imitation of any
colour whatsoever: Their Reds or deep Yellows, they can dilute by mixing
pale Yellows with them, and deepen their pale by mixing deeper with them;
for it is not with Opacous colours as it is with transparent, where by adding
more Yellow to yellow, it is deepned, but in opacous diluted. They can
whiten any colour by mixing White with it, and darken any colour by
mixing Black, or some dark and dirty colour. And in a word, most of the
colours, or colour’d bodies they use in Limning and Painting, are such, as
though mixt with any other of their colours, they preserve their own hue,
and by being in such very smal parts dispers’d through the other colour’d
bodies, they both, or altogether represent to the eye a compositum of all; the
eye being unable, by reason of their smalness, to distinguish the peculiarly
colour’d particles, but receives them as one intire compositum: whereas in
many of these, the Microscope very easily distinguishes each of the
compounding colours distinct, and exhibiting its own colour.
Thus have I by gently mixing Vermilion and Bise dry, produc’d a very
fine Purple, or mixt colour, but looking on it with the Microscope, I could
easily distinguish both the Red and the Blue particles, which did not at all
produce the Phantasm of Purple.
To summ up all therefore in a word, I have not yet found any solid
colour’d body, that I have yet examin’d, perfectly opacous; but those that
are least transparent are Metalline and Mineral bodies, whose particles

generally, seeming either to be very small, or very much flaw’d, appear for
the most part opacous, though there are very few of them that I have look’d
on with a Microscope, that have not very plainly or circumstantially
manifested themselves transparent.
And indeed, there seem to be so few bodies in the world that are in
minimis opacous, that I think one may make it a rational Query, Whether
there be any body absolutely thus opacous? For I doubt not at all (and I
have taken notice of very many circumstances that make me of this mind)
that could we very much improve the Microscope, we might be able to see
all those bodies very plainly transparent, which we now are fain onely to
ghess at by circumstances. Nay, the Object Glasses we yet make use of are
such, that they make many transparent bodies to the eye, seem opacous
through them, which if we widen the Aperture a little, and cast more light
on the objects, and not charge the Glasses so deep, will again disclose their
transparency.
Now, as for all kinds of colours that are dissolvable in Water, or other
liquors, there is nothing so manifest, as that all those ting’d liquors are
transparent; and many of them are capable of being diluted and
compounded or mixt with other colours, and divers of them are capable of
being very much chang’d and heightned, and fixt with several kinds of
Saline menstruums. Others of them upon compounding, destroy or vitiate
each others colours, and precipitate, or otherwise very much alter each
others tincture. In the true ordering and diluting, and deepning, and mixing,
and fixing of each of which, consists one of the greatest mysteries of the
Dyers; of which particulars, because our Microscope affords us very little
information, I shall add nothing more at present; but onely that with a very
few tinctures order’d and mixt after certain ways, too long to be here set
down, I have been able to make an appearance of all the various colours
imaginable, without at all using the help of Salts, or Saline menstruums to
vary them.
As for the mutation of Colours by Saline menstruums, they have already
been so fully and excellently handled by the lately mention’d Incomparable
Authour, that I can add nothing, but that of a multitude of trials that I made,
I have found them exactly to agree with his Rules and Theories; and though
there may be infinite instances, yet may they be reduc’d under a few Heads,

and compris’d within a very few Rules. And generally I find, that Saline
menstruums are most operative upon those colours that are Purple, or have
some degree of Purple in them, and upon the other colours much less. The
spurious pulses that compose which, being (as I formerly noted) so very
neer the middle between the true ones, that a small variation throws them
both to one side, or both to the other, and so consequently must make a vast
mutation in the formerly appearing Colour.

Observ. XI. Of Figures observ’d in small Sand.
Sand generally seems to be nothing else but exceeding small Pebbles, or
at least some very small parcels of a bigger stone; the whiter kind seems
through the Microscope to consist of small transparent pieces of some
pellucid body, each of them looking much like a piece of Alum, or Salt
Gem; and this kind of Sand is angled for the most part irregularly, without
any certain shape, and the granules of it are for the most part flaw’d,
through amongst many of them it is not difficult to find some that are
perfectly pellucid, like a piece of clear Crystal, and divers likewise most
curiously shap’d, much after the manner of the bigger Stiriæ of Crystal, or
like the small Diamants I observ’d in certain Flints, of which I shall by and
by relate; which last particular seems to argue, that this kind of Sand is not
made by the comminution of greater transparent Crystaline bodies, but by
the concretion or coagulation of Water, or some other fluid body.
There are other kinds of courser Sands, which are browner, and have
their particles much bigger; these, view’d with a Microscope, seem much
courser and more opacous substances, and most of them are of some
irregularly rounded Figures; and though they seem not so opacous as to the
naked eye, yet they seem very foul and cloudy, but neither do these want
curiously transparent, no more than they do regularly figur’d and well
colour’d particles, as I have often found.
There are multitudes of other kinds of Sands, which in many particulars,
plainly enough discoverable by the Microscope, differ both from these last
mention’d kinds of Sands, and from one another: there seeming to be as
great variety of Sands, as there is of Stones. And as amongst Stones some
are call’d precious from their excellency, so also are there Sands which
deserve the same Epithite for their beauty; for viewing a small parcel of
East-India Sand (which was given me by my highly honoured friend, Mr.
Daniel Colwall) and, since that, another parcel, much of the same kind, I
found several of them, both very transparent like precious Stones, and
regularly figur’d like Crystal, Cornish Diamants, some Rubies, &c. and also
ting’d with very lively and deep colours, like Rubys, Saphyrs, Emeralds,

&c. These kinds of granules I have often found also in English Sand. And
’tis easie to make such a counterfeit Sand with deeply ting’d Glass,
Enamels and Painters colours.
It were endless to describe the multitudes of Figures I have met with in
these kind of minute bodies, such as Spherical, Oval, Pyramidal, Conical,
Prismatical, of each of which kinds I have taken notice.
But amongst many others, I met with none more observable than this
Schem. 5.
Fig. X. pretty Shell (described in the Figure X. of the fifth Scheme) which,
though as it was light on by chance, deserv’d to have been omitted (I being
unable to direct any one to find the like) yet for its rarity was it not
inconsiderable, especially upon the account of the information it may afford
us. For by it we have a very good instance of the curiosity of Nature in
another kind of Animals which are remov’d, by reason of their minuteness,
beyond the reach of our eyes, so that as there are several sorts of Insects, as
Mites, and others, so small as not yet to have had any names; (some of
which I shall afterwards describe) and small Fishes, as Leeches in Vinegar;
and smal vegetables, as Moss, and Rose-Leave-plants; and small
Mushroms, as mould: so are there, it seems, small Shel-fish likewise,
Nature shewing her curiosity in every Tribe of Animals, Vegetables, and
Minerals.
I was trying several small and single Magnifying Glasses, and casually
viewing a parcel of white Sand, when I perceiv’d one of the grains exactly
shap’d and wreath’d like a Shell, but endeavouring to distinguish it with my
naked eye, it was so very small, that I was fain again to make use of the
Glass to find it; then, whilest I thus look’d on it, with a Pin I separated all
the rest of the granules of Sand, and found it afterwards to appear to the
naked eye an exceeding small white spot, no bigger than the point of a Pin.
Afterwards I view’d it every way with a better Microscope and found it on
both sides, and edge-ways, to resemble the Shell of a small Water-Snail
with a flat spiral Shell: it had twelve wreathings, a, b, c, d, e, &c. all very
proportionably growing one less than another toward the middle or center
of the Shell, where there was a very small round white spot. I could not
certainly discover whether the Shell were hollow or not, but it seem’d fill’d

with somewhat, and ’tis probable that it might be petrify’d as other larger
Shels often are, such as are mention’d in the seventeenth Observation.

Observ. XII. Of Gravel in Urine.
I Have often observ’d the Sand or Gravel of Urine, which seems to be a
tartareous substance, generated out of a saline and a terrestrial substance
crystalliz’d together, in the form of Tartar, sometimes sticking to the sides
of the Urinal, but for the most part sinking to the bottom, and there lying in
the form of coorse common Sand; these, through the Microscope, appear to
be a company of small bodies, partly transparent and partly opacous, some
White, some Yellow, some Red, others of more brown and duskie colours.
The Figure of them is for the most part flat, in the manner of Slats or
such like plated Stones, that is, each of them seem to be made up of several
other thinner Plates, much like Muscovie Glass, or English Sparr to the last
of which, the white plated Gravel seems most likely; for they seem not
onely plated like that, but their sides shap’d also into Rhombs, Rhomboeids,
and sometimes into Rectangles and Squares. Their bigness and Figure may
be Schem. 7.
Fig. 2. seen in the second Figure of the seventh Plate, which represents about
a dozen of them lying upon a plate ABCD, some of which, as a, b, c, d
seem’d more regular than the rest, and e, which was a small one, sticking on
the top of another, was a perfect Rhomboeid on the top, and had four
Rectangular sides.
The line E which was the measure of the Microscope, is ¹⁄₃₂ part of an
English Inch, so that the greatest bredth of any of them, exceeded not ¹⁄₁₂₈
part of an Inch.
Putting these into several liquors, I found oyl of Vitriol, Spirit of Urine,
and several other Saline menstruums to dissolve them; and the first of these
in less than a minute without Ebullition, Water, and several other liquors,
had no sudden operation upon them. This I mention, because those liquors
that dissolve them, first make them very white, not vitiating, but rather
rectifying their Figure, and thereby make them afford a very pretty object
for the Microscope.

How great an advantage it would be to such as are troubled with the
Stone, to find some menstruum might dissolve them without hurting the
Bladder, is easily imagin’d, since some injections made of such bodies
might likewise dissolve the stone, which seems much of the same nature.
It may therefore, perhaps, be worthy some Physicians enquiry, whether
there may not be something mixt with the Urine in which the Gravel or
Stone lies, which may again make it dissolve it, the first of which seems by
it’s regular Figures to have been sometimes Crystalliz’d out of it. For
whether this Crystallization be made in the manner as Alum, Peter, &c. are
crystallized out of a cooling liquor, in which, by boyling they have been
dissolv’d; or whether it be made in the manner of Tartarum Vitriolatum, that
is, by the Coalition of an acid and a Sulphureous substance, it seems not
impossible, but that the liquor it lies in, may be again made a dissolvent of
it. But leaving these inquiries to Physicians or Chymists, to whom it does
more properly belong, I shall proceed.

Observ. XIII. Of the small Diamants, or Sparks in
Flints.
Chancing to break a Flint stone in pieces, I found within it a certain
cavity all crusted over with a very pretty candied substance, some of the
parts of which, upon changing the posture of the Stone, in respect of the
Incident light, exhibited a number of small, but very vivid reflections; and
having made use of my Microscope, I could perceive the whole surface of
that cavity to be all beset with a multitude of little Crystaline or Adamantine
bodies, so curiously shap’d, that it afforded a not unpleasing object.
Having considered those vivid repercussions of light, I found them to be
made partly from the plain external surface of these regularly figured bodies
(which afforded the vivid reflections) and partly to be made from within the
somewhat pellucid body, that is, from some surface of the body, opposite to
that superficies of it which was next the eye.
And because these bodies were so small, that I could not well come to
make Experiments and Examinations of them, I provided me several small
stiriæ of Crystals or Diamants, found in great quantities in Cornwall and are
therefore commonly called Cornish Diamants: these being very pellucid,
and growing in a hollow cavity of a Rock (as I have been several times
informed by those that have observ’d them) much after the same manner as
these do in the Flint, and having besides their outward surface very
regularly shap’d, retaining very near the same Figures with some of those I
observ’d in the other, became a convenient help to me for the Examination
of the proprieties of those kinds of bodies.
And first for the Reflections, in these I found it very observable, That the
brightest reflections of light proceeded from within the pellucid body; that
is, that the Rays admitted through the pellucid substance in their getting out
on the opposite side, were by the contiguous and strong reflecting surface of
the Air very vividly reflected, so that more Rays were reflected to the eye
by this surface, though the Ray in entring and getting out of the Crystal had

suffer’d a double refraction, than there were from the outward surface of the
Glass where the Ray had suffer’d no refraction at all.
And that this was the surface of the Air that gave so vivid a re-percussion
I try’d by this means I sunk half of a stiria in Water, so that only Water was
contiguous to the under surface, and then the internal reflection was so
exceedingly faint, that it was scarce discernable. Again, I try’d to alter this
vivid reflection by keeping off the Air, with a body not fluid, and that was
by rubbing and holding my finger very hard against the under surface, so as
in many places the pulp of my finger did touch the Glass, without any
interjacent air between, then observing the reflection, I found, that
wheresoever my finger or skin toucht the surface, from that part there was
no reflection, but in the little furrows or creases of my skin, where there
remain’d little small lines of air, from them was return’d a very vivid
reflection as before. I try’d further, by making the surface of very pure
Quicksilver to be contiguous to the under surface of this pellucid body, and
then the reflection from that was so exceedingly more vivid than from the
air, as the reflection from air was than the reflection from the Water; from
all which trials I plainly saw, that the strong reflecting air was the cause of
this Phænomenon.
And this agrees very well with the Hypothesis of light and Pellucid
bodies which I have mention’d in the description of Muscovy-glass; for we
there suppose Glass to be a medium, which does less resist the pulse of
light, and consequently, that most of the Rays incident on it enter into it,
and are refracted towards the perpendicular; whereas the air I suppose to be
a body that does more resist it, and consequently more are re-percuss’d then
do enter it: the same kind of trials have I made, with Crystalline Glass, with
drops of fluid bodies, and several other ways, which do all seem to agree
very exactly with this Theory. So that from this Principle well establish’d,
we may deduce severall Corollaries not unworthy observation.
And the first is; that it plainly appears by this, that the production of the
Rainbow is as much to be ascribed to the reflection of the concave surface
of the air, as to the refraction of the Globular drops: this will be evidently
manifest by these Experiments, if you foliate that part of a Glass-ball that is
to reflect an Iris, as in the Cartesian Experiment, above mention’d, the
reflections will be abundantly more strong, and the colours more vivid: and

if that part of the surface be touch’d with Water, scarce affords any sensible
colour at all.
Next we learn, that the great reason why pellucid bodies beaten small are
white, is from the multitude of reflections, not from the particles of the
body, but from the contiguous surface of the air. And this is evidently
manifested, by filling the Interstitia of those powder’d bodies with Water,
whereby their whiteness presently disappears. From the same reason
proceeds the whiteness of many kinds of Sands, which in the Microscope
appear to be made up of a multitude of little pellucid bodies, whose
brightest reflections may by the Microscope be plainly perceiv’d to come
from their internal surfaces; and much of the whiteness of it may be
destroy’d by the affusion of fair Water to be contiguous to those surfaces.
The whiteness also of froth, is for the most part to be ascribed to the
reflection of the light from the surface of the air within the Bubbles, and
very little to the reflection from the surface of the Water it self: for this last
reflection does not return a quarter so many Rays, as that which is made
from the surface of the air, as I have certainly found by a multitude of
Observations and Experiments.
The whiteness of Linnen, Paper, Silk, &c. proceeds much from the same
reason, as the Microscope will easily discover; for the Paper is made up of
an abundance of pellucid bodies, which afford a very plentifull reflection
from within, that is, from the concave surface of the air contiguous to its
component particles; wherefore by the affusion of Water, Oyl, Tallow,
Turpentine, &c. all those reflections are made more faint, and the beams of
light are suffer’d to traject & run through the Paper more freely.
Hence further we may learn the reason of the whiteness of many bodies,
and by what means they may be in part made pellucid: As white Marble for
instance, for this body is composed of a pellucid body exceedingly flaw’d,
that is, there are abundance of thin, and very fine cracks or chinks amongst
the multitude of particles of the body, that contain in them small parcels of
air, which do so re-percuss and drive back the penetrating beams, that they
cannot enter very deep within that body; which the Microscope does plainly
inform us to be made up of a Congeries of pellucid particles. And I further
found it somewhat more evidently by some attempts I made towards the

making transparent Marble, for by heating the Stone a little, and soaking it
in Oyl, Turpentine, Oyl of Turpentine, &c., I found that I was able to see
much deeper into the body of Marble than before; and one trial, which was
not with an unctuous substance, succeeded better than the rest, of which,
when I have a better opportunity, I shall make further trial.
This also gives us a probable reason of the so much admired
Phænomena, of the Oculus Mundi, an Oval stone, which commonly looks
like white Alabaster, but being laid a certain time in Water, it grows
pellucid, and transparent, and being suffer’d to lie again dry, it by degrees
loses that transparency, and becomes white as before. For the Stone being
of a hollow spongie nature, has in the first and last of these appearances, all
those pores fill’d with the obtunding and reflecting air; whereas in the
second, all those pores are fill’d with a medium that has much the same
refraction with the particles of the Stone, and therefore those two being
contiguous, make, as ’twere, one continued medium, of which more is said
in the 15. Observation.
There are a multitude of other Phænomena, that are produc’d from this
same Principle, which as it has not been taken notice of by any yet that I
know, so I think, upon more diligent observation, will it not be found the
least considerable. But I have here onely time to hint Hypotheses, and not to
prosecute them so fully as I could wish; many of them having a vast extent
in the production of a multitude of Phænomena, which have been by others,
either not attempted to be explain’d, or else attributed to some other cause
than what I have assign’d, and perhaps than the right; and therefore I shall
leave this to the prosecution of such as have more leisure: onely before I
leave it, I must not pretermit to hint, that by this Principle, multitudes of the
Phænomena of the air, as about Mists, Clouds, Meteors, Haloes, &c. are
most plainly and (perhaps) truly explicable; multitudes also of the
Phænomena in colour’d bodies, as liquors, &c. are deducible from it.
And from this I shall proceed to a second considerable Phænomenon
which these Diamants exhibit, and that is the regularity of their Figure,
which is a propriety not less general than the former, It comprising within
its extent, all kinds of Metals, all kinds of Minerals, most Precious stones,
all kinds of Salts, multitudes of Earths, and almost all kinds of fluid bodies.
And this is another propiety, which, though a little superficially taken notice

of by some, has not, that I know, been so much as attempted to be
explicated by any.
This propriety of bodies, as I think it the most worthy, and next in order
to be consider’d after the contemplation of the Globular Figure, so have I
long had a desire as wel as a determination to have prosecuted it if I had
had an opportunity, having long since propos’d to my self the method of my
enquiry therein, it containing all the allurements that I think any enquiry is
capable of: For, first I take it to proceed from the most simple principle that
any kind of form can come from, next the Globular, which was therefore
the first I set upon, and what I have therein perform’d, I leave the Judicious
Reader to determine. For as that form proceeded from a propiety of fluid
bodies, which I have call’d Congruity, or Incongruity; so I think, had I time
and opportunity, I could make probable, that all these regular Figures that
are so conspicuously various and curious, and do so adorn and beautifie
such multitudes of bodies, as I have above hinted, arise onely from three or
four several positions or postures of Globular particles, and those the most
plain, obvious, and necessary conjunctions of such figur’d particles that are
possible, so that supposing such and such plain and obvious causes
concurring the coagulating particles must necessarily compose a body of
such a determinate regular Figure, and no other, and this with as much
necessity and obviousness as a fluid body encompast with a Heterogeneous
fluid must be protruded into a Spherule or Globe. And this I have ad oculum
demonstrated with a company of bullets, and some few other very simple
bodies; so that there was not any regular Figure, which I have hitherto met
withall, of any of those bodies that I have above named, that I could not
with the composition of bullets or globules, and one or two other bodies,
imitate, even almost by shaking them together. And thus for instance may
we find that the Globular bullets will of themselves, if put on an inclining
plain, so that they may run together, naturally run into a triangular order,
composing all the variety of figures that can be imagin’d to be made out of
æquilateral triangles; and such will you find, upon trial, all the Surfaces of
Alum to be compos’d of: For three bullets lying on a plain, as close to one
another as they can compose an Schem. 7.
Fig. A. &c. æquilatero-triangular form, as in A in the 7. Scheme. If a fourth be
joyn’d to them on either side as closely as it can, they four compose the
most regular Rhombus consisting of two æquilateral triangles, as B. If a

fifth be joyn’d to them on either side in as close a position as it can, which
is the propriety of the Texture, it makes a Trapezium, or four-sided Figure,
two of whose angles are 120. and two 60. degrees, as C. If a sixth be added,
as before, either it makes an æquilateral triangle, as D, or a Rhomboeid, as
E, or an Hexangular Figure, as F, which is compos’d of two primary
Rhombs. If a seventh be added, it makes either an æquilatero-hexagonal
Figure, as G, or some kind of six-sided Figure, as H, or I. And though there
be never so many placed together, they may be rang’d into some of these
lately mentioned Figures, all the angles of which will be either 60. degrees,
or 120. as the figure K. which is an æquiangular hexagonal Figure is
compounded of 12. Globules, or may be of 25, or 27, or 36, or 42, &c. and
by these kinds of texture, or position of globular bodies, may you find out
all the variety of regular shapes, into which the smooth surfaces of Alum are
form’d, as upon examination any one may easily find; nor does it hold only
in superficies, but in solidity also, for it’s obvious that a fourth Globule laid
upon the third in this texture, composes a regular Tetrahedron, which is a
very usual Figure of the Crystals of Alum. And (to hasten) there is no one
Figure into which Alum is observ’d to be crystallized, but may by this
texture of Globules be imitated, and by no other.
I could instance also in the Figure of Sea-salt, and Sal-gem, that it is
compos’d of a texture of Globules, placed in a cubical form, as L, and that
all the Figures of those Salts may be imitated by this texture of Globules
and by no other whatsoever. And that the forms of Vitriol and of Salt-Peter,
as also of Crystal, Hore-frost, &c. are compounded of these two textures,
but modulated by certain proprieties: But I have not here time to insist
upon, as I have not neither to shew by what means Globules come to be
thus context, and what those Globules are, and many other particulars
requisite to a full and intelligible explication of this propriety of bodies. Nor
have I hitherto found indeed an opportunity of prosecuting the inquiry so
farr as I design’d; nor do I know when I may, it requiring abundance of
time, and a great deal of assistance to go through with what I design’d; the
model of which was this:
First, to get as exact and full a collection as I could, of all the differing
kinds of Geometrical figur’d bodies, some three or four several bodies of
each kind.

Secondly, with them to get as exact a History as possibly I could learn of
their places of Generation or finding, and to enquire after as many
circumstances that tended to the Illustrating of this Enquiry, as possibly I
could observe.
Thirdly, to make as many trials as upon experience I could find requisite,
in Dissolutions and Coagulations of several crystallizing Salts; for the
needfull instruction and information in this Enquiry.
Fourthly, to make several trials on divers other bodies, as Metals,
Minerals, and Stones, by dissolving them in several Menstruums, and
crystalizing them, to see what Figures would arise from those several
Compositums.
Fifthly, to make Compositions and Coagulations of several Salts together
into the same mass, to observe of what Figure the product of them would
be; and in all, to note as many circumstances as I should judge conducive to
my Enquiry.
Sixthly, to enquire the closeness or rarity of the texture of these bodies,
by examining their gravity, and their refraction, &c.
Seventhly, to enquire particularly what operations the fire has upon
several kinds of Salts, what changes it causes in their Figures, Textures, or
Energies.
Eighthly, to examine their manner of dissolution, or acting upon those
bodies dissoluble in them; The texture of those bodies before and after the
process. And this for the History.
Next for the Solution, To have examin’d by what, and how many means,
such and such Figures, actions and effects could be produc’d possibly.
And lastly, from all circumstances well weigh’d, I should have
endeavoured to have shewn which of them was most likely, and (if the
informations by these Enquiries would have born it) to have demonstrated
which of them it must be, and was.
But to proceed, As I believe it next to the Globular the most simple; so do
I, in the second place, judge it not less pleasant; for that which makes an

Enquiry pleasant, are, first a noble Inventum that promises to crown the
successfull endeavour; and such must certainly the knowledge of the
efficient and concurrent causes of all these curious Geometrical Figures be,
which has made the Philosophers hitherto to conclude nature in these things
to play the Geometrician, according to that saying of Plato, Ὁ Θεὸς
γεομετρεῖ. Or next, a great variety of matter in the Enquiry; and here we
meet with nothing less than the Mathematicks of nature, having every day a
new Figure to contemplate, or a variation of the same in another body,
Which do afford us a third thing, which will yet more sweeten the
Enquiry, and that is, a multitude of information; we are not so much to
grope in the dark, as in most other Enquiries, where the Inventum is great;
for having such a multitude of instances to compare, and such easie ways of
generating, or compounding and of destroying the form, as in the Solution
and Crystallization of Salts, we cannot but learn plentifull information to
proceed by. And this will further appear from the universality of the
Principle which Nature has made use of almost in all inanimate bodies. And
therefore, as the contemplation of them all conduces to the knowledg of any
one; so from a Scientifical knowledge of any one does follow the fame of
all, and every one.
And fourthly, for the usefulness of this knowledge, when acquir’d;
certainly none can doubt, that considers that it caries us a step forward into
the Labyrinth of Nature, in the right way towards the end we propose our
selves in all Philosophical Enquiries. So that knowing what is the form of
Inanimate or Mineral bodies, we shall be the better able to proceed in our
next Enquiry after the forms of Vegetative bodies; and last of all, of
Animate ones, that seeming to be the highest step of natural knowledge that
the mind of man is capable of.

Observ. XIV. Of several kindes of frozen Figures.
I have very often in a Morning, when there has been a great hoar-frost,
with an indifferently magnifying Microscope, observ’d the small Stiriæ, or
Crystalline beard, which then usually covers the face of most bodies that lie
open to the cold air, and found them to be generally Hexangular prismatical
bodies, much like the long Crystals of Salt-peter, save onely that the ends of
them were differing: for whereas those of Nitre are for the most part
pyramidal, being terminated either in a point or edge; these of Frost were
hollow, and the cavity in some seem’d pretty deep, and this cavity was the
more plainly to be seen, because usually one or other of the six
parallelogram sides was wanting, or at least much shorter then the rest.
But this was onely the Figure of the Bearded hoar-frost; and as for the
particles of other kinds of hoar-frosts, they seem’d for the most part
irregular, or of no certain Figure. Nay, the parts of those curious branchings,
or vortices, that usually in cold weather tarnish the surface of Glass, appear
through the Microscope very rude and unshapen, as do most other kinds of
frozen Figures, which to the naked eye seem exceeding neat and curious,
such as the Figures of Snow, frozen Urine, Hail, several Figures frozen in
common Water, &c. Some Observations of each of which I shall hereunto
annex, because if well consider’d and examin’d, they may, perhaps, prove
very instructive for the finding out of what I have endeavoured in the
preceding Observation to shew, to be (next the Globular Figure which is
caus’d by congruity, as I hope I have made probable in the sixth
Observation) the most simple and plain operation of Nature, of which,
notwithstanding we are yet ignorant.

I.

Several Observables in the six-branched Figures form’d on the
surface of Urine by freezing.
Schem. 8.
Fig. 1.

1 The Figures were all frozen almost even with the surface of the Urine
in the Vessel; but the bigger stems were a little prominent above that
surface, and the parts of those stems which were nearest the center (a) were
biggest above the surface.
2 I have observ’d several kinds of these Figures, some smaller, no bigger
then a Two-pence, others so bigg, that I have by measure found one of its
stems or branches above four foot long; and of these, some were pretty
round, having all their branches pretty neer alike; other of them were more
extended towards one side, as usually those very large ones were, which I
have observ’d in Ditches which have been full of foul water.
3 None of all these Figures I have yet taken notice of, had any regular
position in respect of one another, or of the sides of the Vessel; nor did I
find any of them equally to exactness extended every way from the center
a.
4 Where ever there was a center, the branchings from it, ab, ac, ad, ae,
af, ag, were never fewer, or more then six, which usually concurr’d, or met
one another very neer in the same point or center, a; though oftentimes not
exactly; and were enclin’d to each other by an angle, of very near sixty
degrees, I say, very neer, because, though having endeavoured to measure
them the most accurately I was able, with the largest Compasses I had, I
could not find any sensible variation from that measure, yet the whole six-
branched Figure seeming to compose a solid angle, they must necessarily
be somewhat less.
5 The middle lines or stems of these branches, ab, ac, ad, ae, af, ag,
seem’d somewhat whiter, and a little higher then any of the intermediate
branchings of these Figures; and the center a, was the most prominent part
of the whole Figure, seeming the apex of a solid angle or pyramid, each of
the six plains being a little enclin’d below the surface of the Urin.
6 The lateral branchings issuing out of the great ones, such as op, mq, &c.
were each of them inclin’d to the great ones, by the same angle of about
sixty degrees, as the great ones were one to another, and always the bigger
branchings were prominent above the less, and the less above the least, by
proportionate gradations.

7 The lateral branches shooting out of the great ones, went all of them
from the center, and each of them was parallel to that great branch, next to
which it lay; so that as all the branches on one side were parallel to one
another, so were they all of them to the approximate great branch, as po, qr,
as they were parallel to each other, and shot from the center, so were they
parallel also to the great branch ab.
8 Some of the stems of the six branches proceeded straight, and of a
thickness that gradually grew sharper towards the end, as ag.
9 Others of the stems of those branches grew bigger and knotty towards
the middle, and the branches also as well as stems, from Cylinders grew
into Plates, in a most admirable and curious order, so exceeding regular and
delicate, as nothing could be more, as is visible in ab, ac, ad, ae, af, but
towards the end of some of these stems, they began again to grow smaller
and to recover their former branchings, as about k and n.
10 Many of the lateral branches had collateral branches (if I may so call
them) as qm had many such as st, and most of those again subcollateral, as
vw, and these again had others less, which one may call laterosubcollateral,
and these again others, and they others, &c. in greater Figures.
11 The branchings of the main Stems joyn’d not together by any regular
line, nor did one side of the one lie over the other side of the other, but the
small collateral and subcollateral branches did lie at top of one another
according to a certain order or method, which I always observ’d to be this.
12 That side of a collateral or subcollateral, &c. branch, lay over the side
of the approximate (as the feathers in the wing of a Bird) whose branchings
proceeded parallel to the last biggest stem from which it sprung, and not to
the biggest stem of all, unless that were a second stem backwards.
13 This rule that held in the branchings of the Sexangular Figure held
also in the branchings of any other great or small stem, though it did not
proceed from a center.
14 The exactness and curiosity of the figuration of these branches, was in
every particular so transcendent, that I judge it almost impossible for
humane art to imitate.

15 Tasting several cleer pieces of this Ice, I could not find any Urinous
taste in them, but those few I tasted, seem’d as insipid as water.
16 A figuration somewhat like this, though indeed in some particulars
much more curious, I have several times observ’d in regulus martis
stellatus, but with this difference, that all the stems and branchings are
bended in a most excellent and regular order, whereas in Ice the stems and
branchings are streight, but in all other particulars it agrees with this, and
seems indeed nothing but one of these stars, or branched Figures frozen on
Urine, distorted, or wreathed a little, with a certain proportion: Lead also
that has Arsenick and some other things mixt with it, I have found to have
its surface, when suffer’d to cool, figured somewhat like the branchings of
Urine, but much smaller.
17 But there is a Vegetable which does exceedingly imitate these
branches, and that is, Fearn, where the main stem may be observ’d to shoot
out branches, and the stems of each of these lateral branches, to send forth
collateral, and those subcollateral and those laterosubcollateral, &c. and
all those much after the same order with the branchings, divisions, and
subdivisions in the branchings of these Figures in frozen Urine; so that if
the Figures of both be well consider’d, one would ghess that there were not
much greater need of a seminal principle for the production of Fearn, then
for the production of the branches of Urine, or the Stella martis, there
seeming to be as much form and beauty in the one as in the other.
And indeed, this Plant of Fearn, if all particulars be well consider’d, will
seem of as simple, and uncompounded a form as any Vegetable, next to
Mould or Mushromes, and would next after the invention of the forms of
those, deserve to be enquir’d into; for notwithstanding several have
affirm’d it to have seed, and to be propagated thereby; yet, though I have
made very diligent enquiry after that particular, I cannot find that there is
any part of it that can be imagin’d to be more seminal then another: But this
onely here by the by:
For the freezing Figures in Urine, I found it requisite,
First, that the Superficies be not disturbed with any wind, or other
commotion of the air, or the like.

Secondly, that it be not too long exposed, so as that the whole bulk be
frozen, for oftentimes, in such cases, by reason of the swelling the of Ice, or
from some other cause, the curious branched Figures disappear.
Thirdly, an artificial freezing with Snow and Salt, apply’d to the outside
of the containing Vessel, succeeds not well, unless there be a very little
quantity in the Vessel.
Fourthly, If you take any cleer and smooth Glass, and wetting all the
inside of it with Urine, you expose it to a very sharp freezing, you will find
it cover’d with a very regular and curious Figure.

II.

Observables in figur’d Snow.

Exposing a piece of black Cloth, or a black Hatt to the falling Snow, I
have often with great pleasure, observ’d such an infinite variety of
curiously figur’d Snow, that it would be as impossible to draw the Figure
and shape of every one of them, as to imitate exactly the curious and
Geometrical Mechanisme of Nature in any one. Some coorse draughts, such
as the coldness of the weather, and the ill provisions, I had by me for such a
purpose, would permit me to make, I Schem. 8.
Fig. 2. have here added in the Second Figure of the Eighth Scheme.

In all which I observ’d, that if they were of any regular Figures, they
were always branched out with six principal branches, all of equal length,
shape and make, from the center, being each of them inclin’d to either of
the next branches on either side of it, by an angle of sixty degrees.
Now, as all these stems were for the most part in one flake exactly of the
same make, so were they in differing Figures of very differing ones; so that
in a very little time I have observ’d above an hundred several cizes and
shapes of these starry flakes.
The branches also out of each stem of any one of these flakes, were
exactly alike in the same flake; so that of whatever Figure one of the
branches were, the other five were sure to be of the same, very exactly, that
is, if the branchings of the one were small Perallelipipeds or Plates, the

branchings of the other five were of the same; and generally, the branchings
were very conformable to the rules and method observ’d before, in the
Figures on Urine, that is, the branchings from each side of the stems were
parallel to the next stem on that side, and if the stems were plated, the
branches also were the same; if the stems were very long, the branches also
were so, &c.
Observing some of these figur’d flakes with a Microscope, I found them
not to appear so curious and exactly figur’d as one would have imagin’d,
but like Artificial Figures, the bigger they were magnify’d, the more
irregularities appear’d in them; but this irregularity seem’d ascribable to the
thawing and breaking of the flake by the fall, and not at all to the defect of
the plastick virtue of Nature, whose curiosity in the formation of most of
these kind of regular Figures, such as those of Salt, Minerals, &c. appears
by the help of the Microscope, to be very many degrees smaller then the
most acute eye is able to perceive without it. And though one of these six-
branched Stars appear’d here below much of the shape described Schem. 8.
Fig. 3. in the Third Figure of the Eighth Scheme; yet I am very apt to think,
that could we have a sight of one of them through a Microscope as they are
generated in the Clouds before their Figures are vitiated by external
accidents, they would exhibit abundance of curiosity and neatness there
also, though never so much magnify’d: For since I have observ’d the
Figures of Salts and Minerals to be some of them so exceeding small, that I
have scarcely been able to perceive them with the Microscope, and yet have
they been regular, and since (as far as I have yet examin’d it) there seems to
be but one and the same cause that produces both these effects, I think it not
irrational to suppose that these pretty figur’d Stars of Snow, when at first
generated might be also very regular and exact.

III.

Several kinds of Figures in Water frozen.

Putting fair Water into a large capacious Vessel of Glass, and exposing it
to the cold, I observ’d after a little time, several broad, flat, and thin
laminæ, or plates of Ice, crossing the bulk of the water and one another very
irregularly, onely most of them seem’d to turn one of their edges towards

that side of the Glass which was next it, and seem’d to grow, as ’twere from
the inside of the Vessel inwards towards the middle, almost like so many
blades of Fern. Having taken several of these plates out of water on the
blade of a Knife, I observ’d them figur’d much after the manner of Herring
bones, or Fern blades, that is, there was one bigger stem in the middle like
the back-bone, and out of it, on either side, were a multitude of small stiriæ,
or icicles, like the smaller bones, or the smaller branches in Fern, each of
these branches on the one side, were parallel to all the rest on the same side,
and all of them seem’d to make an angle with the stem, towards the top, of
sixty degrees, and towards the bottom or root of this stem, of 120. See the
fourth Figure of the 8. Plate.
I observ’d likewise several very pretty Varieties of Figures in Water,
frozen on the top of a broad flat Marble-stone, expos’d to the cold with a
little Water on it, some like feathers, some of other shapes, many of Schem. 8.
Fig. 5. them were very much of the shape exprest in the fifth Figure of the 8.
Scheme, which is extremely differing from any of the other Figures.
I observ’d likewise, that the shootings of Ice on the top of Water,
beginning to freeze, were in streight prismatical bodies much like those of
roch-peter, that they crost each other usually without any kind of order or
rule, that they were always a little higher then the surface of the Water that
lay between them; that by degrees those interjacent spaces would be fill’d
with Ice also, which usually would be as high as the surface of the rest.
In flakes of Ice that had been frozen on the top of Water to any
considerable thickness, I observ’d that both the upper and the under sides of
it were curiously quill’d, furrow’d, or grain’d, as it were, which when the
Sun shone on the Plate, was exceeding easily to be Schem. 8.
Fig. 6. perceiv’d to be much after the shape of the lines in the 6. Figure of the
8. Scheme, that is, they consisted of several streight ends of parallel Plates,
which were of divers lengths and angles to one another without any certain
order.
The cause of all which regular Figures (and of hundreds of others,
namely of Salts, Minerals, Metals, &c. which I could have here inserted,
would it not have been too long) seems to be deducible from the same
Principles, which I have (in the 13. Observation) hinted only, having not yet

had time to compleat a Theory of them. But indeed (which I there also
hinted) I judge it the second step by which the Pyramid of natural
knowledge (which is the knowledge of the form of bodies) is to be
ascended: And whosoever will climb it, must be well furnish’d with that
which the Noble Verulam calls Scalam Intellectus; he must have scaling
Ladders, otherwise the steps are so large and high, there will be no getting
up them, and consequently little hopes of attaining any higher station, such
as to the knowledge of the most simple principle of Vegetation manifested
in Mould and Mushromes, which, as I elsewhere endeavoured to shew,
seems to be the third step; for it seems to me, that the Intellect of man is
like his body, destitute of wings, and cannot move from a lower to a higher
and more sublime station of knowledg, otherwise then step by step, nay
even there where the way is prepar’d and already made passible; as in the
Elements of Geometry, or the like, where it is fain to climb a whole series of
Propositions by degrees, before it attains the knowledge of one Probleme.
But if the ascent be high, difficult and above its reach, it must have recourse
to a novum organum, some new engine and contrivance, some new kind of
Algebra, or Analytick Art before it can surmount it.

Observ. XV. Of Kettering-stone, and of the pores
of Inanimate bodies.
Schem. 9.
Fig. 1.

This Stone which is brought from Kettering in Northampton-Shire, and
digg’d out of a Quarry, as I am inform’d, has a grain altogether admirable,
nor have I ever seen or heard of any other stone that has the like. It is made
up of an innumerable company of small bodies, not all of the same cize or
shape, but for the most part, not much differing from a Globular form, nor
exceed they one another in Diameter above three or four times; they appear
to the eye, like the Cobb or Ovary of a Herring, or some smaller fishes, but
for the most part, the particles seem somewhat less, and not so uniform; but
their variation from a perfect globular ball, seems to be only by the pressure
of the contiguous bals which have a little deprest and protruded those toucht
sides inward, and forc’d the other sides as much outwards beyond the limits
of a Globe; just as it would happen, if a heap of exactly round Balls of soft
Clay were heaped upon one another; or, as I have often seen a heap of small
Globules of Quicksilver, reduc’d to that form by rubbing it much in a glaz’d
Vessel, with some slimy or sluggish liquor, such as Spittle, when though the
top of the upper Globules be very neer spherical, yet those that are prest
upon by others, exactly imitate the forms of these lately mention’d grains.
Where these grains touch each other, they are so firmly united or settled
together, that they seldom part without breaking a hole in one or th’other of
them, such as a, a, a, b, c, c, &c. Some of which fractions, as a, a, a, a,
where the touch has been but light, break no more then the outward crust, or
first shell of the stone, which is of a white colour, a little dash’d with a
brownish Yellow, and is very thin, like the shell of an Egg: and I have seen
some of those grains perfectly resemble some kind of Eggs, both in colour
and shape: But where the union of the contiguous granules has been more
firm, there the divulsion has made a greater Chasm, as at b, b, b, in so much
that I have observ’d some of them quite broken in two, as at c, c, c, which
has discovered to me a further resemblance they have to Eggs, they having

an appearance of a white and yelk, by two differing substances that
envelope and encompass each other.
That which we may call the white was pretty whitish neer the yelk, but
more duskie towards the shell; some of them I could plainly perceive to be
shot or radiated like a Pyrites or fire-stone; the yelk in some I saw hollow,
in others fill’d with a duskie brown and porous substance like a kind of pith.
The small pores, or interstitia eeee betwixt the Globules, I plainly saw,
and found by other trials to be every way pervious to air and water, for I
could blow through a piece of this stone of a considerable thickness, as
easily as I have blown through a Cane, which minded me of the pores
which Des Cartes allow his materia subtilis between the æthereal globules.
The object, through the Microscope, appears like a Congeries or heap of
Pibbles, such as I have often seen cast up on the shore, by the working of
the Sea after a great storm, or like (in shape, though not colour) a company
of small Globules of Quicksilver, look’d on with a Microscope, when
reduc’d into that form by the way lately mentioned. And perhaps, this last
may give some hint at the manner of the formation of the former: For
supposing some Lapidescent substance to be generated, or some way
brought (either by some commixture of bodies in the Sea it self, or
protruded in, perhaps, out of some subterraneous caverns) to the bottom of
the Sea, and there remaining in the form of a liquor like Quicksilver,
heterogeneous to the ambient Saline fluid, it may by the working and
tumblings of the Sea to and fro be jumbled and comminuted into such
Globules as may afterwards be hardned into Flints, the lying of which one
upon another, when in the Sea, being not very hard, by reason of the weight
of the incompassing fluid, may cause the undermost to be a little, though
not much, varied from a globular Figure. But this only by the by.
After what manner this Kettering-stone should be generated I cannot
learn, having never been there to view the place, and observe the
circumstances; but it seems to me from the structure of it to be generated
from some substance once more fluid, and afterwards by degrees growing
harder, almost after the same manner as I supposed the generation of Flints
to be made.

But whatever were the cause of its curious texture, we may learn this
information from it; that even in those things which we account vile, rude,
and coorse, Nature has not been wanting to shew abundance of curiosity
and excellent Mechanisme.
We may here find a Stone by help of a Microscope, to be made up of
abundance of small Balls, which do but just touch each other, and yet there
being so many contacts, they make a firm hard mass, or a Stone much
harder then Free-stone.
Next, though we can by a Microscope discern so curious a shape in the
particles, yet to the naked eye there scarce appears any such thing; which
may afford us a good argument to think, that even in those bodies also,
whose texture we are not able to discern, though help’d with Microscopes,
there may be yet latent so curious a Schematisme, that it may abundantly
satisfie the curious searcher, who shall be so happy as to find some way to
discover it.
Next, we here find a Stone, though to the naked eye a very close one, yet
every way perforated with innumerable pores, which are nothing else but
the interstitia, between those multitudes of minute globular particles, that
compose the bulk it self, and these pores are not only discover’d by the
Microscope, but by this contrivance.
I took a pretty large piece of this stone, and covering it all over with
cement, save only at two opposite parts, I found my self able, by blowing in
at one end that was left open, to blow my spittle, with which I had wet the
other end, into abundance of bubbles, which argued these pores to be open
and pervious through the whole stone, which affords us a very pretty
instance of the porousness of some seemingly close bodies, of which kind I
shall anon have occasion to subjoyn many more, tending to prove the same
thing.
I must not here omit to take notice, that in this body there is not a
vegetative faculty that should so contrive this structure for any peculiar use
of Vegetation or growth, whereas in the other instances of vegetable porous
bodies, there is an anima or forma informans, that does contrive all the
Structures and Mechanisms of the constituting body, to make them
subservient and usefull to the great Work or Function they are to perform.

And so I ghess the pores in Wood, and other vegetables, in bones, and other
Animal substances, to be as so many channels, provided by the Great and
Alwise Creator, for the conveyance of appropriated juyces to particular
parts. And therefore, that this may tend, or be pervious all towards one part,
and may have impediments, as valves or the like, to any other; but in this
body we have very little reason so suspect there should be any such design,
for it is equally pervious every way, not onely forward, but backwards, and
side-ways, and seems indeed much rather to be Homogeneous or similar to
those pores, which we may with great probability believe to be the channels
of pellucid bodies, not directed, or more open any one way, then any other,
being equally pervious every way. And, according as these pores are more
or greater in respect of the interstitial bodies, the more transparent are the
so constituted concretes; and the smaller those pores are, the weaker is the
Impulse of light communicated through them, though the more quick be the
progress.
Upon this Occasion, I hope it will not be altogether unseasonable, if I
propound my conjectures and Hypothesis about the medium and
conveyance of light.
I suppose then, that the greatest part of the Interstitia of the world, that
lies between the bodies of the Sun and Starrs, and the Planets, and the
Earth, to be an exceeding fluid body, very apt and ready to be mov’d, and to
communicate the motion of any one part to any other part, though never so
far distant: Nor do I much concern my self, to determine what the Figure of
the particles of this exceedingly subtile fluid medium must be, nor whether
it have any interstitiated pores or vacuities, it being sufficient to solve all
the Phænomena to suppose it an exceedingly fluid, or the most fluid body
in the world, and as yet impossible to determine the other difficulties.
That being so exceeding fluid a body, it easily gives passage to all other
bodies to move to and fro in it.
That it neither receives from any of its parts, or from other bodies; nor
communicates to any of its parts, or to any other body, any impulse, or
motion in a direct line, that is not of a determinate quickness. And that
when the motion is of such determinate swiftness, it both receives, and

communicates, or propagates an impulse or motion to any imaginable
distance in streight lines, with an unimaginable celerity and vigour.
That all kind of solid bodies consist of pretty massie particles in respect
of the particles of this fluid medium, which in many places do so touch each
other, that none of this fluid medium interposes much after the same manner
(to use a gross similitude) as a heap of great stones compose one great
congeries or mass in the midst of the water.
That all fluid bodies which we may call tangible, are nothing but some
more subtile parts of those particles, that serve to constitute all tangible
bodies.
That the water, and such other fluid bodies, are nothing but a congeries
of particles agitated or made fluid by it in the same manner as the particles
of Salt are agitated or made fluid by a parcel of water, in which they are
dissolv’d, and subsiding to the bottom of it, constitute a fluid body, much
more massie and dense, and less fluid then the pure water it self.
That the air on the other side is a certain company of particles of quite
another kind, that is, such as are very much smaller, and more easily
moveable by the motion of this fluid medium; much like those very subtile
parts of Cochenel, other very deep tinging bodies, where by a very small
parcel of matter is able to tinge and diffuse it self over a very great quantity
of the fluid dissolvent; or somewhat after that manner, as smoak, and such
like minute bodies, or steams, are observ’d to tinge a very great quantity of
air; onely this last similitude is deficient in one propriety, and that is a
perpetuity or continuance in that state of commixture with the air, but the
former does more nearly approach to the nature and manner of the air’s
being dissolv’d by this fluid or Æther. And this Similitude will further hold
in these proprieties; that as those tinctures may be increased by certain
bodies, so may they be precipitated by others, as I shall afterwards shew it
to be very probable, that the like accidents happen even to the Air it self.
Further, as these solutions and tinctures do alter the nature of these fluid
bodies, as to their aptness to propagate a motion or impulse through them,
even so does the particles of the Air, Water, and other fluid bodies, and of
Glass, Crystal, &c. which are commixt with this bulk of the Æther alter the
motion of the propagated pulse of light; that is, where these more bulkie

particles are more plentifull, and consequently a lesser quantity of the
Æther between them to be mov’d, there the motion must necessarily be the
swifter, though not so robust, which will produce those effects, which I
have (I hope) with some probability, ascribed to it in the digression about
Colours, at the end of the Observations on Muscovy-glass.
Now, that other Stones, and those which have the closest and hardest
textures, and seem (as far as we are able to discover with our eyes, though
help’d with the best Microscopes) freest from pores, are yet
notwithstanding replenish’d with them, an Instance or two will, I suppose,
make more probable.
A very solid and unflaw’d piece of cleer white Marble, if it be well
polish’d and glaz’d, has so curiously smooth a surface, that the best and
most polish’d surface of any wrought-glass, seems not to the naked eye, nor
through a Microscope, to be more smooth, and less porous. And yet, that
this hard close body is replenish’d with abundance of pores, I think these
following Experiments will sufficiently prove.
The first is, That if you take such a piece, and for a pretty while boyl it in
Turpentine and Oyl of Turpentine, you shall find that the stone will be all
imbu’d with it; and whereas before it look’d more white, but more opacous,
now it will look more greasie, but be much more transparent, and if you let
it lie but a little while, and then break off a part of it, you shall find the
unctuous body to have penetrated it to such a determinate depth every way
within the surface. This may be yet easier try’d with a piece of the same
Marble, a little warm’d in the fire, and then a little Pitch or Tarr melted on
the top of it; for these black bodies, by their insinuating themselves into the
invisible pores of the stone, ting it with so black a hue, that there can be no
further doubt of the truth of this assertion, that it abounds with small
imperceptible pores.
Now, that other bodies will also sink into the pores of Marble, besides
unctuous, I have try’d, and found, that a very Blue tincture made in spirit of
Urine would very readily and easily sink into it, as would also several
tinctures drawn with spirit of Wine.
Nor is Marble the only seemingly close stone, which by other kinds of
Experiments may be found porous; for I have by this kind of Experiment on

divers other stones found much the same effect, and in some, indeed much
more notable. Other stones I have found so porous, that with the
Microscope I could perceive several small winding holes, much like Worm-
holes, as I have noted in some kind of Purbeck-stone, by looking on the
surface of a piece newly flaw’d off, for if otherwise, the surface has been
long expos’d to the Air, or has been scraped with any tool, those small
caverns are fill’d with dust, and disappear.
And to confirm this Conjecture, yet further, I shall here insert an
excellent account, given into the Royal Society by that Eminently Learned
Physician, Doctor Goddard, of an Experiment, not less instructive then
curious and accurate, made by himself on a very hard and seemingly close
stone call’d Oculus Mundi, as I find it preserv’d in the Records of that
Honourable Society.

A small stone of the kind, call’d by some Authours, Oculus
Mundi, being dry and cloudy, weigh’d 5²⁰⁹⁄₂₅₆ Grains.
The same put under water for a night, and somewhat more,
became transparent, and the superficies being wiped dry, weighed
6³⁄₂₅₆ Grains.

The difference between these two weights, 0⁵⁰⁄₂₅₆ of a Grain.
The same Stone kept out of water one Day and becoming
cloudy again weighed, 5²²⁵⁄₂₅₆ Graines.
Which was more then the first weight, 0¹⁶⁄₂₅₆ of a Grain.

The same being kept two Days longer weighed, 5²⁰²⁄₂₅₆
Graines.
Which was less then at first, 0⁷⁄₂₅₆ a Grain.
Being kept dry something longer it did not grow sensibly
lighter.
Being put under water for a night and becoming again
transparent and wiped dry, the weight was, 6³⁄₂₅₆ Grains, the same

with the first after putting in water, and more then the last weight
after keeping of it dry, 0⁵⁷⁄₂₅₆ of a Grain.
Another Stone of the same kind being variegated with milky
white and gray like some sorts of Agates, while it lay under water,
was alwaies invironed with little Bubbles, such as appear in water
a little before boyling, next the sides of the Vessel.
There were also some the like Bubbles on the Surface of the
water just over it, as if either some exhalations came out of it, or
that it did excite some fermentation in the parts of the water
contiguous to it.
There was little sensible difference in the transparency of this
Stone, before the putting under water, and after: To be sure the
milky-white parts continued as before, but more difference in
weight then in the former. For whereas before the putting into the
water the weight was 18⁹⁷⁄₁₂₈ Graines. After it had lyen in about
four and twenty hours the weight was 20²⁷⁄₁₂₈ Graines, so the
difference was, 1⁵⁸⁄₁₂₈ Graines.
The same Stone was infused in the water scalding hot, and so
continued for a while after it was cold, but got no more weight
then upon infusing in the cold, neither was there any sensible
Difference in the weight both times.

In which Experiment, there are three Observables that seem very
manifestly to prove the porousness of these seemingly close bodies: the first
is their acquiring a transparency, and losing their whiteness after steeping in
water, which will seem the more strongly to argue it, if what I have already
said about the making transparent, or clarifying of some bodies, as the
white powder of beaten Glass, and the froth of some glutinous transparent
liquor be well consider’d; for thereby it will seem rational to think that this
transparency arises from the insinuation of the water (which has much the
same refraction with such stony particles, as may be discover’d by Sand
view’d with a Microscope) into those pores which were formerly repleat
with air (that has a very differing refraction, and consequently is very
reflective) which seems to be confirm’d by the second Observable, namely,
the increase of weight after keeping, and decrease upon drying. And thirdly,

seem’d yet more sensibly confirm’d by the multitude of bubbles in the last
Experiment.
We find also most Acid Salts very readily to dissolve and separate the
parts of this body one from another; which is yet a further Argument to
confirm the porousness of bodies, and will serve as such, to shew that even
Glass also has an abundance of pores in it, since there are several liquors,
that with long staying in a Glass, will so Corrode and eat into it, as at last,
to make it pervious to the liquor it contain’d, of which I have seen very
many Instances.
Since therefore we find by other proofs, that many of those bodies which
we think the most solid ones, and appear so to our sight, have
notwithstanding abundance of those grosser kind of pores, which will admit
several kinds of liquors into them, why should we not believe that Glass,
and all other transparent bodies abound with them, since we have many
other arguments, besides the propagation of light, which seem to argue for
it?
And whereas it may be objected, that the propagation of light is no
argument that there are those atomical pores in glass, since there are
Hypotheses plausible enough to solve those Phænomena, by supposing the
pulse onely to be communicated through the transparent body.
To this I answer, that that Hypothesis which the industrious Mersennus
has publish’d about the slower motion of the end of a Ray in a denser
medium, then in a more rare and thin, seems altogether unsufficient to solve
abundance of Phænomena, of which this is not the least considerable, that it
is impossible from that supposition, that any colours should be generated
from the refraction of the Rays; for since by that Hypothesis the undulating
pulse is always carried perpendicular, or at right angles with the Ray or
Line of direction, it follows, that the stroke of the pulse of light, after it has
been once or twice refracted (through a Prisme, for example) must affect
the eye with the same kind of stroke as if it had not been refracted at all.
Nor will it be enough for a Defendant of that Hypothesis, to say, that
perhaps it is because the refractions have made the Rays more weak, for if
so, then two refractions in the two parallel sides of a Quadrangular Prisme
would produce colours, but we have no such Phænomena produc’d.

There are several Arguments that I could bring to evince that there are in
all transparent bodies such atomical pores. And that there is such a fluid
body as I am arguing for, which is the medium, or Instrument, by which the
pulse of Light is convey’d from the lucid body to the enlightn’d. But that it
being a digression from the Observations I was recording, about the Pores
of Kettering Stone, it would be too much such, if I should protract it too
long; and therefore I shall proceed to the next Observation.

Observ. XVI. Of Charcoal, or burnt Vegetables.
Charcoal, or a Vegetable burnt black, affords an object no less pleasant
than instructive, for if you take a small round Charcoal, and break it short
with your fingers, you may perceive it to break with a very smooth and
sleek surface, almost like the surface of black sealing Wax; this surface, if it
be look’d on with an ordinary Microscope, does manifest abundance of
those pores which are also visible to the eye in many kinds of Wood, rang’d
round the pith, both a in kind of circular order, and a radiant one. Of these
there are a multitude in the substance of the Coal, every where almost
perforating and drilling it from end to end; by means of which, be the Coal
never so long, you may easily blow through it; and this you may presently
find, by wetting one end of it with Spittle, and blowing at the other.
But this is not all, for besides those many great and conspicuous irregular
spots or pores, if a better Microscope be made use of, there will appear an
infinite company of exceedingly small, and very regular pores, so thick and
so orderly set, and so close to one another, that they leave very little room
or space between them to be fill’d with a solid body, for the apparent
interstitia or separating sides of these pores seem so thin in some places,
that the texture of a Honey-comb cannot be more porous. Though this be
not every where so, the intercurrent partitions in some places being very
much thicker in proportion to the holes.
Most of these small pores seem’d to be pretty round, and were rang’d in
rows that radiated from the pith to the bark; they all of them seem’d to be
continued open pores, running the whole length of the Stick; and that they
were all perforated, I try’d by breaking off a very thin sliver of the Coal
cross-ways, and then with my Microscope, diligently surveying them
against the light, for by that means I was able to see quite through them.
These pores were so exceeding small and thick, that in a line of them, ¹⁄₁₈
part of an Inch long, I found by numbering them no less then 150. small
pores; and therefore in a line of them an Inch long, must be no less then
2700. pores, and in a circular area of an Inch diameter, must be about

5725350. of the like pores; so that a Stick of an Inch Diameter, may contain
no less then seven hundred and twenty five thousand, besides 5 Millions of
pores, which would, I doubt not, seem even incredible, were not every one
left to believe his own eyes. Nay, having since examin’d Cocus, black and
green Ebony, Lignum Vitæ, &c. I found, that all these Woods have their
pores, abundantly smaller then those of soft light Wood; in so much, that
those of Guajacum seem’d not above an eighth part of the bigness of the
pores of Beech, but then the Interstitia were thicker; so prodigiously
curious are the contrivances, pipes, or sluces by which the Succus nutritius,
or Juyce of a Vegetable is convey’d from place to place.
This Observation seems to afford us the true reason of several
Phænomena of Coals; as
First, why they look black; and for this we need go no further then the
Scheme, for certainly, a body that has so many pores in it as this is
discover’d to have, from each of which no light is reflected, must
necessarily look black, especially, when the pores are somewhat bigger in
proportion to the intervals then they are cut in the Scheme, black being
nothing else but a privation of Light, or a want of reflection; and
wheresoever this reflecting quality is deficient, there does that part look
black, whether it be from a porousness of the body, as in this Instance, or in
a deadning and dulling quality, such as I have observ’d in the Scoria of
Lead, Tin, Silver, Copper, &c.
Next, we may also as plainly see the reason of its shining quality, and
that is from the even breaking off of the stick, the solid interstitia having a
regular termination or surface, and having a pretty strong reflecting quality,
the many small reflections become united to the naked eye, and make a
very pretty shining surface.
Thirdly, the reason of its hardness and brittleness seems evident, for since
all the watery or liquid substance that moistn’d and toughn’d those
Interstitia of the more solid parts, are evaporated and remov’d, that which is
left behind becomes of the nature almost of a stone, which will not at all, or
very little, bend without a divulsion or solution of its continuity.
It is not my design at present, to examine the use and Mechanisme of
these parts of Wood, that being more proper to another Enquiry; but rather

to hint, that from this Experiment we may learn,
First, what is the cause of the blackness of many burnt bodies, which we
may find to be nothing else but this; that the heat of the fire agitating and
rarifying the waterish, transparent, and volatile water that is contain’d in
them, by the continuation of that action, does so totally expel and drive
away all that which before fill’d the pores, and was dispers’d also through
the solid mass of it, and thereby caus’d an universal kind of transparency,
that it not onely leaves all the pores empty, but all the Interstitia also so dry
and opacous, and perhaps also yet further perforated, that that light onely is
reflected back which falls upon the very outward edges of the pores, all
they that enter into the pores of the body, never returning, but being lost in
it.
Now, that the Charring or coaling of a body is nothing else, may be easily
believ’d by one that shall consider the means of its production, which may
be done after this, or any such manner. The body to be charr’d or coal’d,
may be put into a Crucible, Pot, or any other Vessel that will endure to be
made red-hot in the fire without breaking, and then cover’d over with Sand,
so as no part of it be suffer’d to be open to the Air, then set into a good fire,
and there kept till the Sand has continu’d red hot for a quarter, half, an hour
or two, or more, according to the nature and bigness of the body to be
coal’d or charr’d, then taking it out of the fire, and letting it stand till it be
quite cold, the body may be taken out of the Sand well charr’d and cleans’d
of its waterish parts; but in the taking of it out, care must be had that the
Sand be very neer cold, for else, when it comes into the free air, it will take
fire, and readily burn away.
This maybe done also in any close Vessel of Glass, as a Retort, or the
like, and the several fluid substances that come over may be receiv’d in a fit
Recipient, which will yet further countenance this Hypothesis: And their
manner of charring Wood in great quantity comes much to the same thing,
namely, an application of a great heat to the body, and preserving it from the
free access of the devouring air; this may be easily learn’d from the History
of Charring of Coal, most excellently describ’d and publish’d by that most
accomplish’d Gentleman, Mr. John Evelin, in the 100, 101, 103, pages of
his Sylva, to which I shall therefore refer the curious Reader that desires a
full information of it.

Next, we may learn what part of the Wood it is that is the combustible
matter, for since we shall find that none, or very little of those fluid
substances that are driven over into the Receiver are combustible, and that
most of that which is left behind is so, it follows, that the solid interstitia of
the Wood are the combustible matter. Further, the reason why uncharr’d
Wood burns with a greater flame then that which is charr’d, is as evident,
because those waterish or volatil parts issuing out of the fired Wood, every
way, not onely shatter and open the body, the better for the fire to enter, but
issuing out in vapours or wind, they become like so many little æolipiles, or
Bellows, whereby they blow and agitate the fir’d part, and conduce to the
more speedy and violent consumption or dissolution of the body.
Thirdly, from the Experiment of charring of Coals (whereby we see that
notwithstanding the great heat, and the duration of it, the solid parts of the
Wood remain, whilest they are preserv’d from the free access of the air
undissipated) we may learn, that which has not, that I know of, been
publish’d or hinted, nay, not so much as thought of, by any; and that in
short is this.
First, that the Air in which we live, move, and breath, and which
encompasses very many, and cherishes most bodies it encompasses, that
this Air is the menstruum, or universal dissolvent of all Sulphureous bodies.
Secondly, that this action it performs not, till the body be first sufficiently
heated, as we find requisite also to the dissolution of many other bodies by
several other menstruums.
Thirdly, that this action of dissolution, produces or generates a very great
heat, and that which we call Fire; and this is common also to many
dissolutions of other bodies, made by menstruums, of which I could give
multitudes of Instances.
Fourthly, that this action is perform’d with so great a violence, and does
so minutely act, and rapidly agitate the smallest parts of the combustible
matter, that it produces in the diaphanous medium of the Air, the action or
pulse of light, which what it is, I have else-where already shewn.
Fifthly, that the dissolution of sulphureous bodies is made by a substance
inherent, and mixt with the Air, that is like, if not the very same, with that

which is fixt in Salt-peter, which by multitudes of Experiments that may be
made with Salt-peter, will, I think, most evidently be demonstrated.
Sixthly, that in this dissolution of bodies by the Air, a certain part is
united and mixt, or dissolv’d and turn’d into the Air, and made to fly up and
down with it in the same manner as a metalline or other body dissolved into
any menstruums, does follow the motions and progresses of that menstruum
till it be precipitated.
Seventhly, That as there is one part that is dissoluble by the Air, so are
there other parts with which the parts of the Air mixing and uniting, do
make a Coagulum, or precipitation, as one may call it, which causes it to be
separated from the Air, but this precipitate is so light, and in so small and
rarify’d or porous clusters, that it is very volatil, and is easily carry’d up by
the motion of the Air, though afterwards, when the heat and agitation that
kept it rarify’d ceases, it easily condenses, and commixt with other
indissoluble parts, it sticks and adheres to the next bodies it meets withall;
and this is a certain Salt that may be extracted out of Soot.
Eighthly, that many indissoluble parts being very apt and prompt to be
rarify’d, and so, whilest they continue in that heat and agitation, are lighter
then the Ambient Air, are thereby thrust and carry’d upwards with great
violence, and by that means carry along with them, not onely that Saline
concrete I mention’d before, but many terrestrial, or indissoluble and
irrarefiable parts, nay, many parts also which are dissoluble, but are not
suffer’d to stay long enough in a sufficient heat to make them prompt and
apt for that action. And therefore we find in Soot, not onely a part, that
being continued longer in a competent heat, will be dissolv’d by the Air, or
take fire and burn; but a part also which is fixt, terrestrial, and irrarefiable.
Ninthly, that as there are these several parts that will rarifie and fly, or be
driven up by the heat, so are there many others, that as they are indissoluble
by the aerial menstruum, so are they of such sluggish and gross parts, that
they are not easily rarify’d by heat, and therefore cannot be rais’d by it; the
volatility or fixtness of a body seeming to consist only in this, that the one
is of a texture, or has component parts that will be easily rarify’d into the
form of Air, and the other, that it has such as will not, without much ado, be
brought to such a constitution; and this is that part which remains behind in

a white body call’d Ashes, which contains a substance, or Salt, which
Chymists call Alkali: what the particular natures of each of these bodies are,
I shall not here examine, intending it in another place, but shall rather add
that this Hypothesis does so exactly agree with all Phænomena, of Fire, and
so genuinely explicate each particular circumstance that I have hitherto
observ’d, that it is more then probable, that this cause which I have assign’d
is the true adequate, real, and onely cause of those Phænomena; And
therefore I shall proceed a little further, to shew the nature and use of the
Air.
Tenthly, therefore the dissolving parts of the Air are but few, that is, it
seems of the nature of those Saline menstruums, or spirits, that have very
much flegme mixt with the spirits, and therefore a small parcel of it is
quickly glutted, and will dissolve no more; and therefore unless some fresh
part of this menstruum be apply’d to the body to be dissolv’d, the action
ceases, and the body leaves to be dissolv’d and to shine, which is the
Indication of it, though plac’d or kept in the greatest heat; whereas Salt-
peter is a menstruum, when melted and red-hot, that abounds more with
those Dissolvent particles, and therefore as a small quantity of it will
dissolve a great sulphureous body, so will the dissolution be very quick and
violent.
Therefore in the Eleventh place, it is observable, that, as in other
solutions, if a copious and quick supply of fresh menstruum, though but
weak, be poured on, or applied to the dissoluble body, it quickly consumes
it: So this menstruum of the Air, if by Bellows, or any other such
contrivance, it be copiously apply’d to the shining body, is found to
dissolve it as soon, and as violently as the more strong menstruum of melted
Nitre.
Therefore twelfthly, it seems reasonable to think that there is no such
thing as an Element of Fire that should attract or draw up the flame, or
towards which the flame should endeavour to ascend out of a desire or
appetite of uniting with that as its Homogeneal primitive and generating
Element; but that that shining transient body which we call Flame, is
nothing else but a mixture of Air, and volatil sulphureous parts of dissoluble
or combustible bodies, which are acting upon each other whilst they ascend,
that is, flame seems to be a mixture of Air, and the combustible volatil parts

of any body, which parts the encompassing Air does dissolve or work upon,
which action, as it does intend the heat of the aerial parts of the dissolvent,
so does it thereby further rarifie those parts that are acting, or that are very
neer them, whereby they growing much lighter then the heavie parts of that
Menstruum that are more remote, are thereby protruded and driven upward;
and this may be easily observ’d also in dissolutions made by any other
menstruum, especially such as either create heat or bubbles. Now, this
action of the Menstruum, or Air, on the dissoluble parts, is made with such
violence, or is such, that it imparts such a motion or pulse to the diaphanous
parts of the Air, as I have elsewhere shewn is requisite to produce light.
This Hypothesis I have endeavoured to raise from an Infinite of
Observations and Experiments, the process of which would be much too
long to be here inserted, and will perhaps another time afford matter
copious enough for a much larger Discourse, the Air being a Subject which
(though all the world has hitherto liv’d and breath’d in, and been
unconversant about) has yet been so little truly examin’d or explain’d, that a
diligent enquirer will be able to find but very little information from what
has been (till of late) written of it: But being once well understood, it will, I
doubt not, inable a man to render an intelligible, nay probable, if not the
true reason of all the Phænomena of Fire, which, as it has been found by
Writers and Philosophers of all Ages a matter of no small difficulty, as may
be sufficiently understood by their strange Hypotheses, and unintelligible
Solutions of some few Phænomena of it; so will it prove a matter of no
small concern and use in humane affairs, as I shall elsewhere endeavour to
manifest when I come to shew the use of the Air in respiration, and for the
preservation of the life, nay, for the conservation and restauration of the
health and natural constitution of mankind as well as all other aereal
animals, as also the uses of this principle or propriety of the Air in
chymical, mechanical, and other operations. In this place I have onely time
to hint an Hypothesis, which, if God permit me life and opportunity, I may
elsewhere prosecute, improve and publish. In the mean time, before I finish
this Discourse, I must not forget to acquaint the Reader, that having had the
liberty granted me of making some trials on a piece of Lignum fossile
shewn to the Royal Society, by the eminently Ingenious and Learned
Physician, Doctor Ent, who receiv’d it for a Present from the famous
Ingenioso Cavalliero de Pozzi, it being one of the fairest and best pieces of

Lignum fossile he had seen; Having (I say) taken a small piece of this
Wood, and examin’d it, I found it to burn in the open Air almost like other
Wood, and insteed of a resinous smoak or fume, it yielded a very
bituminous one, smelling much of that kind of sent: But that which I chiefly
took notice of, was, that cutting off a small piece of it, about the bigness of
my Thumb, and charring it in a Crucible with Sand, after the manner I
above prescrib’d, I found it infinitely to abound with the smaller sort of
pores, so extreamly thick, and so regularly perforating the substance of it
long-ways, that breaking it off across, I found it to look very like an Honey-
comb; but as for any of the second, or bigger kind of pores, I could not find
that it had any; so that it seems, whatever were the cause of its production,
it was not without those small kind of pores which we have onely hitherto
found in Vegetable bodies: and comparing them with the pores which I have
found in the Charcoals that I by this means made of several other kinds of
Wood, I find it resemble none so much as those of Firr, to which it is not
much unlike in grain also, and several other proprieties.
And therefore, what ever is by some, who have written of it, and
particularly by Francisco Stelluto, wrote a Treatise in Italian of that
Subject, which was Printed at Rome, 1637, affirm’d that it is a certain kind
of Clay or Earth, which in tract of time is turn’d into Wood; I rather suspect
the quite contrary, that it was at first certain great Trees of Fir or Pine,
which by some Earthquake, or other casualty, came to be buried under the
Earth, and was there, after a long time’s residence (according to the several
natures of the encompassing adjacent parts) either rotted and turn’d into a
kind of Clay, or petrify’d and turn’d into a kind of Stone, or else had its
pores fill’d with certain Mineral juices, which being stay’d in them, and in
tract of time coagulated, appear’d, upon cleaving out, like small Metalline
Wires, or else from some flames or scorching forms that are the occasion
oftentimes, and usually accompany Earthquakes, might be blasted and
turn’d into Coal, or else from certain subterraneous fires which are affirm’d
by that Authour to abound much about those parts (namely, in a Province of
Italy, call’d Umbria, now the Dutchie of Spoletto, in the Territory of Todi,
anciently call’d Tudor; and between the two Villages of Collesecco and
Rosaro not far distant from the high-way leading to Rome, where it is found
in greater quantity then elsewhere) are by reason of their being
encompassed with Earth, and so kept close from the dissolving Air, charr’d

and converted into Coal. It would be too long a work to describe the several
kinds of pores which I met withall, and by this means discovered in several
other Vegetable bodies; nor is it my present design to expatiate upon
Instances of the same kind, but rather to give a Specimen of as many kinds
as I have had opportunity as yet of observing, reserving the prosecution and
enlarging on particulars till a more fit opportunity; and in prosecution of
this design, I shall here add:

Observ. XVII. Of Petrify’d wood, and other
Petrify’d bodies.
Of this sort of substance, I observ’d several pieces of very differing
kinds, both for their outward shape, colour, grain, texture, hardness, &c.
some being brown and reddish; others gray, like a Hone; others black, and
Flint-like: some soft, like a Slate or Whetstone, others as hard as a Flint,
and as brittle. That which I more particular examin’d, was a piece about the
bigness of a mans hand, which seem’d to have been a part of some large
tree, that by rottenness had been broken off from it before it began to be
petrify’d.
And indeed, all that I have yet seen, seem to have been rotten Wood
before the petrifaction was begun; and not long since, examining and
viewing a huge great Oak, that seem’d with meer age to be rotten as it
stood, I was very much confirm’d in this opinion; for I found, that the grain,
colour, and shape of the Wood, was exactly like this petrify’d substance;
and with a Microscope, I found, that all those Microscopical pores, which in
sappy or firm and sound Wood are fill’d with the natural or innate juices of
those Vegetables, in this they were all empty, like those of Vegetables
charr’d; but with this difference, that they seem’d much larger then I have
seen any in Charcoals; nay, even then those of Coals made of great blocks
of Timber, which are commonly call’d Old-coals.
The reason of which difference may probably be, that the charring of
Vegetables, being an operation quickly perform’d, and whilest the Wood is
sappy, the more solid parts may more easily shrink together, and contract
the pores or interstitia between them, then in the rotten Wood, where that
natural juice seems onely to be wash’d away by adventitious or unnatural
moisture; and so though the natural juice be wasted from between the firm
parts, yet those parts are kept asunder by the adventitious moystures, and so
by degrees settled in those postures.
And this I likewise found in the petrify’d Wood, that the pores were
somewhat bigger then those of Charcoal, each pore being neer upon half as

bigg again, but they did not bear that disproportion which Schem. 10.
Fig. 1, 2. is exprest in the tenth Scheme, between the small specks or pores in
the first Figure (which representeth the pores of Coal or Wood charr’d) and
the black spots of the second Figure (which represent the like
Microscopical pores in the petrify’d Wood) for these last were drawn by a
Microscope that magnify’d the object above six times more in Diameter
then the Microscope by which those pores of Coal were observ’d.
Now, though they were a little bigger, yet did they keep the exact figure
and order of the pores of Coals and of rotten Wood, which last also were
much of the same cize.
The other Observations on this petrify’d substance, that a while since, by
the appointment of the Royal Society, I made, and presented to them an
account of, were these that follow, which had the honour done them by the
most accomplish’d Mr. Evelin, my highly honoured friend, to be inserted
and published among those excellent Observations wherewith his Sylva is
replenish’d, and would therefore have been here omitted, had not the Figure
of them, as they appear’d through the Microscope been before that
engraven.
This Petrify’d substance resembled Wood, in that
First, all the parts of it seem’d not at all dislocated, or alter’d from their
natural Position, whil’st they were Wood, but the whole piece retain’d the
exact shape of Wood, having many of the conspicuous pores of wood still
remaining pores, and shewing a manifest difference visible enough between
the grain of the Wood and that of the bark, especially when any side of it
was cut smooth and polite; for then it appear’d to have a very lovely grain,
like that of some curious close Wood.
Next (it resembled Wood) in that all the smaller and (if I may so call
those which are onely visible with a good magnifying Glass) Microscopical
pores of it appear (both when the substance is cut and polish’d transversly
and parallel to the pores of it) perfectly like the Microscopical pores of
several kinds of Wood, especially like and equal to those of several sorts of
rotten Wood which I have since observ’d, retaining both the shape, position
and magnitude of such pores. It was differing from Wood:

First; in weight, being to common water as 3¼ to 1. whereas there are
few of our English Woods, that when very dry are found to be full as heavie
as water.
Secondly, in hardness, being very neer as hard as a Flint; and in some
places of it also resembling the grain of a Flint: and, like it, it would very
readily cut Glass, and would not without difficulty, especially in some parts
of it, be scratch’d by a black hard Flint: It would also as readily strike fire
against a Steel, or against a Flint, as any common Flint.
Thirdly, in the closeness of it, for though all the Microscopical pores of
this petrify’d substance were very conspicuous in one position, yet by
altering that position of the polish’d surface to the light, it was also
manifest, that those pores appear’d darker then the rest of the body, onely
because they were fill’d up with a more duskie substance, and not because
they were hollow.
Fourthly, in its incombustibleness, in that it would not burn in the fire;
nay, though I kept it a good while red-hot in the flame of a Lamp, made
very intense by the blast of a small Pipe, and a large Charcoal, yet it seem’d
not at all to have diminish’d its extension; but only I found it to have
chang’d its colour, and to appear of a more dark and duskie brown colour;
nor could I perceive that those parts which seem’d to have been Wood at
first, were any thing wasted, but the parts appear’d as solid and close as
before. It was further observable also, that as it did not consume like Wood,
so neither did it crack and flie like a Flint, or such like hard Stone, nor was
it long before it appear’d red-hot.
Fifthly, in its dissolubleness; for putting some drops of distill’d Vinegar
upon the Stone, I found it presently to yield very many Bubbles, just like
those which may be observ’d in spirit of Vinegar when it corrodes corals,
though perhaps many of those small Bubbles might proceed from some
small parcels of Air which were driven out of the pores of this petrify’d
substance by the insinuating liquid menstruum.
Sixthly, in its rigidness, and friability, being not at all flexible but brittle
like a Flint, insomuch that I could with one knock of a Hammer break off a
piece of it, and with a few more, reduce that into a pretty fine powder.

Seventhly, it seem’d also very differing from Wood to the touch, feeling
more cold then Wood usually does, and much like other close stones and
Minerals.
The Reasons of all which Phænomena seem to be,
That petrify’d Wood having lain in some place where it was well soak’d
with petrifying water (that is, such a water as is well impregnated with
stony and earthy particles) did by degrees separate, either by straining and
filtration, or perhaps, by precipitation, cohesion or coagulation, abundance
of stony particles from the permeating water, which stony particles, being
by means of the fluid vehicle convey’d, not onely into the Microscopical
pores, and so perfectly stopping them up, but also into the pores or
interstitia, which may, perhaps, be even in the texture or Schematisme of
that part of the Wood, which, through the Microscope, appears most solid,
do thereby so augment the weight of the Wood, as to make it above three
times heavier then water, and perhaps, six times as heavie as it was when
Wood.
Next, they thereby so lock up and fetter the parts of the Wood, that the
fire cannot easily make them flie away, but the action of the fire upon them
is onely able to Char those parts, as it were, like a piece of Wood, if it be
clos’d very fast up in Clay, and kept a good while red-hot in the fire, will by
the heat of the fire be charr’d and not consum’d, which may, perhaps, also
be somewhat of the cause, why the petrify’d substance appear’d of a dark
brown colour after it had been burnt.
By this intrusion of the petrifying particles, this substance also becomes
hard and friable; for the smaller pores of the Wood being perfectly wedg’d,
and stuft up with those stony particles, the small parts of the Wood have no
places or pores into which they may slide upon bending, and consequently
little or no flexion or yielding at all can be caus’d in such a substance.
The remaining particles likewise of the Wood among the stony particles,
may keep them from cracking and flying when put into the fire, as they are
very apt to do in a Flint.
Nor is Wood the onely substance that may by this kind of transmutation
be chang’d into stone; for I my self have seen and examin’d very many

kinds of substances, and among very credible Authours, we may meet with
Histories of such Metamorphoses wrought almost on all kind of substances,
both Vegetable and Animal, which Histories, it is not my business at
present, either to relate, or epitomise, but only to set down some
Observation I lately made on several kind of petrify’d Shels, found about
Keinsham, which lies within four or five miles of Bristol, which are
commonly call’d Serpentine-stones.
Examining several of these very curiously figur’d bodies (which are
commonly thought to be Stones form’d by some extraordinary Plastick
virtue latent in the Earth it self) I took notice of these particulars:
First, that these figured bodies, or stones, were of very differing
substances, as to hardness: some of Clay, some Marle, some soft Stone,
almost of the hardness of those soft stones which Masons call Fire-stone,
others as hard as Portland stone, others as hard as Marble, and some as hard
as a Flint or Crystal.
Next, they were of very differing substances as to transparency and
colour; some white, some almost black, some brown, some Metalline, or
like Marchasites; some transparent like white Marble, others like flaw’d
Crystal, some gray, some of divers colours; some radiated like those long
petrify’d drops, which are commonly found at the Peak, and in other
subterraneous caverns, which have a kind of pith in the middle.
Thirdly, that they were very different as to the manner of their outward
figuration; for some of them seem’d to have been the substance that had
fill’d the Shell of some kind of Shel-fish; others, to have been the substance
that had contain’d or enwrapp’d one of those Shels, on both which, the
perfect impression either of the inside or outside of such Shells seem’d to
be left, but for the most part, those impressions seem’d to be made by an
imperfect or broken Shell, the great end or mouth of the Shell being always
wanting, and oftentimes the little end, and sometimes half, and in some
there were impressions, just as if there had been holes broken in the
figurating, imprinting or moulding Shell; some of them seem’d to be made
by such a Shell very much brused or flaw’d, insomuch that one would
verily have thought that very figur’d stone had been broken or brused whilst
a gelly, as ’twere, and so hardned, but within in the grain of the stone, there

appear’d not the least sign of any such bruse or breaking, but onely on the
very uttermost superficies.
Fourthly, they were very different, as to their outward covering, some
having the perfect Shell, both in figure, colour, and substance, sticking on
upon its surface, and adhering to it, but might very easily be separated from
it, and like other common Cockle or Scolop-shels, which some of them
most accurately resembled, were very dissoluble in common Vinegar,
others of them, especially those Serpentine, or Helical stones were cover’d
or retained the shining or Pearl-colour’d substance of the inside of a Shel,
which substance, on some parts of them, was exceeding thin, and might
very easily be rubbed off; on other parts it was pretty thick, and retained a
white coat, or flaky substance on the top, just like the outsides of such
Shells; some of them had very large pieces of the Shell very plainly sticking
on to them, which were easily to be broken or flaked off by degrees: they
likewise, some of them retain’d all along the surface of them very pretty
kind of sutures, such as are observ’d in the skulls of several kinds of living
creatures, which sutures were most curiously shap’d in the manner of
leaves, and every one of them in the same Shell, exactly one like another,
which I was able to discover plainly enough with my naked eye, but more
perfectly and distinctly with my Microscope; all these sutures, by breaking
some of these stones, I found to be the termini, or boundings of certain
diaphragms, or partitions, which seem’d to divide the cavity of the Shell
into a multitude of very proportionate and regular cells or caverns, these
Diaphragms, in many of them, I found very perfect and compleat, of a very
distinct substance from that which fill’d the cavities, and exactly of the
same kind with that which covered the outside, being for the most part
whitish, or mother of pearl colour’d.
As for the cavities between those Diaphragms, I found some of them
fill’d with Marle, and others with several kinds of stones, others, for the
most part hollow, onely the whole cavity was usually covered over with a
kind of tartareous petrify’d substance, which stuck about the sides, and was
there shot into very curious regular Figures, just as Tartar, or other
dissolv’d Salts are observ’d to stick and crystallize about the sides of the
containing Vessels; or like those little Diamants which I before observed to
have covered the vaulted cavity of a Flint; others had these cavities all lin’d
with a kind of metalline or marchasite-like substance, which with a

Microscope I could as plainly see most curiously and regularly figured, as I
had done those in a Flint.
From all which, and several other particulars which I observ’d, I cannot
but think, that all these, and most other kinds of stony bodies which are
found thus strangely figured, do owe their formation and figuration, not to
any kind of Plastick virtue inherent in the earth, but to the Shells of certain
Shel-fishes, which, either by some Deluge, Inundation, Earthquake, or some
such other means, came to be thrown to that place, and there to be fill’d
with some kind of Mudd or Clay, or petrifying Water, or some other
substance, which in tract of time has been settled together and hardned in
those shelly moulds into those shaped substances we now find them; that
the great and thin end of these Shells by that Earthquake, or what ever other
extraordinary cause it was that brought them thither, was broken off; and
that many others were otherwise broken, bruised and disfigured; that these
Shells which are thus spirallied and separated with Diaphragmes, were
some kind of Nautili or Porcelane shells; and that others were shells of
Cockles, Muscles, Periwincles, Scolops, &c. of various sorts; that these
Shells in many, from the particular nature of the containing or enclos’d
Earth, or some other cause, have in tract of time rotted and mouldred away,
and onely left their impressions, both on the containing and contained
substances; and so left them pretty loose one within another, so that they
may be easily separated by a knock or two of a Hammer. That others of
these Shells, according to the nature of the substances adjacent to them,
have, by a long continuance in that posture, been petrify’d and turn’d into
the nature of stone, just as I even now observ’d several sorts of Wood to be.
That oftentimes the Shell may be found with one kind of substance within,
and quite another without; having, perhaps, been fill’d in one place, and
afterwards translated to another, which I have very frequently observ’d in
Cockle, Muscle, Periwincle, and other shells, which I have found by the Sea
side. Nay, further, that some parts of the same Shell may be fill’d in one
place, and some other caverns in another, and others in a third, or a fourth,
or a fifth place, for so many differing substances have I found in one of
these petrify’d Shells, and perhaps all these differing from the
encompassing earth or stone; the means how all which varieties may be
caus’d, I think, will not be difficult to conceive, to any one that has taken
notice of those Shells, which are commonly found on the Sea shore: And he

that shall throughly examine several kinds of such curiously form’d stones,
will (I am very apt to think) find reason to suppose their generation or
formation to be ascribable to some such accidents as I have mention’d, and
not to any Plastick virtue: For it seems to me quite contrary to the infinite
prudence of Nature, which is observable in all its works and productions, to
design every thing to a determinate end, and for the attaining of that end,
makes use of such ways as are (as farr as the knowledge of man has yet
been able to reach) altogether consonant, and most agreeable to man’s
reason, and of no way or means that does contradict, or is contrary to
humane Ratiocination; whence it has a long time been a general observation
and maxime, that Nature does nothing in vain; It seems, I say, contrary to
that great Wisdom of Nature, that these prettily shap’d bodies should have
all those curious Figures and contrivances (which many of them are adorn’d
and contriv’d with) generated or wrought by a Plastick virtue, for no higher
end, then onely to exhibite such a form; which he that shall throughly
consider all the circumstances of such kind of Figur’d bodies, will, I think,
have great reason to believe, though, I confess, one cannot presently be able
to find out what Nature’s designs are. It were therefore very desirable, that a
good collection of such kind of figur’d stones were collected; and as many
particulars, circumstances, and informations collected with them as could
be obtained, that from such a History of Observations well rang’d,
examin’d and digested, the true original or production of all those kinds of
stones might be perfectly and surely known; such as are Thunder-stones,
Lapides Stellares, Lapides Judaici, and multitudes of other, whereof
mention is made in Aldonandus, Wormius, and other Writers of Minerals.

Observ. XVIII. Of the Schematisme or Texture of
Cork, and of the Cells and Pores of some other
such frothy Bodies.
I took a good clear piece of Cork, and with a Pen-knife sharpen’d as keen
as a Razor, I cut a piece of it off, and thereby left the surface of it exceeding
smooth, then examining it very diligently with a Microscope, me thought I
could perceive it to appear a little porous; but I could not so plainly
distinguish them, as to be sure that they were pores, much less what Figure
they were of: But judging from the lightness and yielding quality of the
Cork, that certainly the texture could not be so curious, but that possibly, if I
could use some further diligence, I might find it to be discernable with a
Microscope, I with the same sharp Penknife, cut off from the former smooth
surface an exceeding thin piece of it, and placing it on a black object Plate,
because it was it self a white body, and casting the light on it with a deep
plano convex Glass, I could exceeding plainly perceive it to be all
perforated and porous, much like a Honey-comb, but that the pores of it
were not regular; yet it was not unlike a Honey-comb in these particulars.
First, in that it had a very little solid substance, in comparison of the
empty cavity that was contain’d between, as does more manifestly Schem. 11.
Fig. 1. appear by the Figure A and B of the XI. Scheme, for the Interstitia, or
walls (as I may so call them) or partitions of those pores were neer as thin
in proportion to their pores, as those thin films of Wax in a Honey-comb
(which enclose and constitute the sexangular celts) are to theirs.
Next, in that these pores, or cells, were not very deep, but consisted of a
great many little Boxes, separated out of one continued long pore, by
certain Diaphragms, as is visible by the Figure B, which represents a sight
of those pores split the long-ways.
I no sooner discern’d these (which were indeed the first microscopical
pores I ever saw, and perhaps, that were ever seen, for I had not met with
any Writer or Person, that had made any mention of them before this) but

me thought I had with the discovery of them, presently hinted to me the true
and intelligible reason of all the Phænomena of Cork; As,
First, if I enquir’d why it was so exceeding light a body? my Microscope
could presently inform me that here was the same reason evident that there
is found for the lightness of froth, an empty Honey-comb, Wool, a Spunge,
a Pumice-stone, or the like; namely, a very small quantity of a solid body,
extended into exceeding large dimensions.
Next, it seem’d nothing more difficult to give an intelligible reason, why
Cork is a body so very unapt to suck and drink in Water, and consequently
preserves it self, floating on the top of Water, though left on it never so
long: and why it is able to stop and hold air in a Bottle, though it be there
very much condens’d and consequently presses very strongly to get a
passage out, without suffering the least bubble to pass through its substance.
For, as to the first, since our Microscope informs us that the substance of
Cork is altogether fill’d with Air, and that that Air is perfectly enclosed in
little Boxes or Cells distinct from one another. It seems very plain, why
neither the Water, nor any other Air can easily insinuate it self into them,
since there is already within them an intus existens, and consequently, why
the pieces of Cork become so good floats for Nets, and stopples for Viols,
or other close Vessels.
And thirdly, if we enquire why Cork has such a springiness and swelling
nature when compress’d? and how it comes to suffer so great a
compression, or seeming penetration of dimensions, so as to be made a
substance as heavie again and more, bulk for bulk, as it was before
compression, and yet suffer’d to return, is found to extend it self again into
the same space? Our Microscope will easily inform us, that the whole mass
consists of an infinite company of small Boxes or Bladders of Air, which is
a substance of a springy nature, and that will suffer a considerable
condensation (as I have several times found by divers trials, by which I
have most evidently condens’d it into less then a twentieth part of its usual
dimensions neer the Earth, and that with no other strength then that of my
hands without any kind of forcing Engine, such as Racks, Leavers, Wheels,
Pullies, or the like, but this onely by and by) and besides, it seems very
probable that those very films or sides of the pores, have in them a

springing quality, as almost all other kind of Vegetable substances have, so
as to help to restore themselves to their former position.
And could we so easily and certainly discover the Schematisme and
Texture even of these films, and of several other bodies, as we can these of
Cork; there seems no probable reason to the contrary, but that we might as
readily render the true reason of all their Phænomena; as namely, what were
the cause of the springiness, and toughness of some, both as to their
flexibility and restitution. What, of the friability or brittleness of some
others, and the like; but till such time as our Microscope, or some other
means, enable us to discover the true Schematism and Texture of all kinds of
bodies, we must grope, as it were, in the dark, and onely ghess at the true
reasons of things by similitudes and comparisons.
But, to return to our Observation. I told several lines of these pores, and
found that there were usually about threescore of these small Cells placed
end-ways in the eighteenth part of an Inch in length, whence I concluded
there must be neer eleven hundred of them, or somewhat more then a
thousand in the length of an Inch, and therefore in a square Inch above a
Million, or 1166400. and in a Cubick Inch, above twelve hundred Millions,
or 1259712000. a thing almost incredible, did not our Microscope assure us
of it by ocular demonstration; nay, did it not discover to us the pores of a
body, which were they diaphragm’d, like those of Cork, would afford us in
one Cubick Inch, more then ten times as many little Cells, as is evident in
several charr’d Vegetables; so prodigiously curious are the works of Nature,
that even these conspicuous pores of bodies, which seem to be the channels
or pipes through which the Succus nutritius, or natural juices of Vegetables
are convey’d, and seem to correspond to the veins, arteries and other
Vessels in sensible creatures, that these pores I say, which seem to be the
Vessels of nutrition to the vastest body in the World, are yet so exceeding
small, that the Atoms which Epicurus fancy’d would go neer to prove too
bigg to enter them, much more to constitute a fluid body in them. And how
infinitely smaller then must be the Vessels of a Mite, or the pores of one of
those little Vegetables I have discovered to grow on the back side of a Rose-
leaf, and shall anon more fully describe, whose bulk is many millions of
times less then the bulk of the small shrub it grows on; and even that shrub,
many millions of times less in bulk then several trees (that have heretofore
grown in England, and are this day flourishing in other hotter Climates, as

we are very credibly inform’d) if at least the pores of this small Vegetable
should keep any such proportion to the body of it, as we have found these
pores of other Vegetables to do to their bulk. But of these pores I have said
more elsewhere.
To proceed then, Cork seems to be by the transverse constitution of the
pores, a kind of Fungus or Mushrome, for the pores lie like so many Rays
tending from the center, or pith of the tree, outwards; so that if you cut off a
piece from a board of Cork transversly, to the flat of it, you will, as it were,
split the pores, and they will appear just as they are express’d in the Figure
B of the XI. Scheme. But if you shave off a very thin piece from this board,
parallel to the plain of it, you will cut all the pores transversly, and they will
appear almost as they are express’d in the Figure A, save onely the solid
Interstitia will not appear so thick as they are there represented.
So that Cork seems to suck its nourishment from the subjacent bark of
the Tree immediately, and to be a kind of excrescence, or a substance
distinct from the substances of the entire Tree, something analogus to the
Mushrome, or Moss on other Trees, or to the hairs on Animals. And having
enquir’d into the History of Cork, I find it reckoned as an excrescency of
the bark of a certain Tree, which is distinct from the two barks that lie
within it, which are common also to other trees; That ’tis some time before
the Cork that covers the young and tender sprouts comes to be discernable;
That it cracks, flaws, and cleaves into many great chaps, the bark
underneath remaining entire; That it may be separated and remov’d from
the Tree, and yet the two under-barks (such as are also common to that with
other Trees) not at all injur’d, but rather helped and freed from an external
injury. Thus Jonstonus in Dendrologia, speaking de Subere, says, Arbor est
procera, Lignum est robustum, dempto cortice in aquis non fluitat, Cortice
in orbem detracto juvatur, crascescens enim præstringit & strangulat, intra
triennium iterum repletur: Caudex ubi adolescit crassus, cortex superior
densus carnosus, duos digitos crassus, scaber, rimosus, & qui nisi
detrahatur dehiscit, alioque subnascente expellitur, interior qui subest
novellus ita rubet ut arbor minio picta videatur. Which Histories, if well
consider’d, and the tree, substance, and manner of growing, if well
examin’d, would, I am very apt to believe, much confirm this my conjecture
about the origination of Cork.

Nor is this kind of Texture peculiar to Cork onely; for upon examination
with my Microscope, I have found that the pith of an Elder, or almost any
other Tree, the inner pulp or pith of the Cany hollow stalks of several other
Vegetables: as of Fennel, Carrets, Daucus, Bur-docks, Teasels, Fearn, some
kinds of Reeds, &c. have much such a kind of Schematisme, as I have lately
shewn that of Cork, save onely that here the pores are rang’d the long-ways,
or the same ways with the length of the Cane, whereas in Cork they are
transverse.
The pith also that fills that part of the stalk of a Feather that is above the
Quil, has much such a kind of texture, save onely that which way soever I
set this light substance, the pores seem’d to be cut transversly; so that I
ghess this pith which fills the Feather, not to consist of abundance of long
pores separated with Diaphragms, as Cork does, but to be a kind of solid or
hardned froth, or a congeries of very small bubbles consolidated in that
form, into a pretty stiff as well as tough concrete, and that each Cavern,
Bubble, or Cell, is distinctly separate from any of the rest, without any kind
of hole in the encompassing films, so that I could no more blow through a
piece of this kinde of substance, then I could through a piece of Cork, or the
sound pith of an Elder.
But though I could not with my Microscope, nor with my breath, nor any
other way I have yet try’d, discover a passage out of one of those cavities
into another, yet I cannot thence conclude, that therefore there are none
such, by which the Succus nutritius, or appropriate juices of Vegetables,
may pass through them; for, in several of those Vegetables, whil’st green, I
have with my Microscope, plainly enough discover’d these Cells or Poles
fill’d with juices, and by degrees sweating them out; as I have also observed
in green Wood all those long Microscopical pores which appear in Charcoal
perfectly empty of any thing but Air.
Now, though I have with great diligence endeavoured to find whether
there be any such thing in those Microscopical pores of Wood or Piths, as
the Valves in the heart, veins, and other passages of Animals, that open and
give passage to the contain’d fluid juices one way, and shut themselves, and
impede the passage of such liquors back again, yet have I not hitherto been
able to say any thing positive in it; though, me thinks, it seems very
probable, that Nature has in these passages, as well as in those of Animal

bodies, very many appropriated Instruments and contrivances, whereby to
bring her designs and end to pass, which ’tis not improbable, but that some
diligent Observer, if help’d with better Microscopes, may in time detect.
And that this may be so, seems with great probability to be argued from
the strange Phænomena of sensitive Plants, wherein Nature seems to
perform several Animal actions with the same Schematism or Orginization
that is common to all Vegetables, as may appear by some no less instructive
then curious Observations that were made by divers Eminent Members of
the Royal Society on some of these kind of Plants, whereof an account was
delivered in to them by the most Ingenious and Excellent Physician, Doctor
Clark, which, having that liberty granted me by that most Illustrious
Society, I have hereunto adjoyn’d.

Observations on the Humble and Sensible Plants in M Chiffin’s
Garden in Saint James’s Park, made August the 9th, 1661.
Present, the Lord Brouncker, Sr. Robert Moray, Dr. Wilkins, Mr.
Evelin, Dr. Henshaw, and Dr. Clark.

There are four Plants, two of which are little shrub Plants, with
a little short stock, about an Inch above the ground, from whence
are spread several sticky branches, round, streight, and smooth in
the distances between the Sprouts, but just under the Sprouts there
are two sharp thorny prickles, broad in the letting on, as in the
Bramble, one just under the Sprout, the other on the opposite side
of the branch.
Schem. 11.
Fig. 2.

The distances betwixt the Sprouts are usually something more
then an Inch, and many upon a Branch, according to its length,
and they grew so, that if the lower Sprout be on the left side of the
Branch, the next above is on the right, and so to the end, not
sprouting by pairs.
At the end of each Sprout are generally four sprigs, two at the
Extremity, and one on each side, just under it. At the first

sprouting of these from the Branch to the Sprig where the leaves
grow, they are full of little short white hairs, which wear off as the
leaves grow, and then they are smooth as the Branch.
Upon each of these sprigs, are, for the most part, eleven pair of
leaves, neatly set into the uppermost part of the little sprig,
exactly one against another, as it were in little articulations, such
as Anatomists call Enarthrosis, where the round head of a Bone is
received into another fitted for its motion; and standing very fitly
to shut themselves and touch, the pairs just above them closing
somewhat upon them, as in the shut sprig; so is the little round
Pedunculus of this leaf fitted into a little cavity of the sprig,
visible to the eye in a sprig new pluck’d, or in a sprig withered on
the Branch, from which the leaves easily fall by touching.
The leaf being almost an oblong square, and set into the
Pedunculus, at one of the lower corners, receiveth from that not
onely a Spine, as I may call it, which, passing through the leaf,
divides it so length-ways that the outer-side is broader then the
inner next the sprig, but little fibres passing obliquely towards the
opposite broader side, seem to make it here a little muscular, and
fitted to move the whole leaf, which, together with the whole
sprig, are set full with little short whitish hairs.
One of these Plants, whose branch seem’d to be older and more
grown then the other, onely the tender Sprouts of it, after the
leaves are shut, fall and hang down; of the other, the whole
branches fall to the ground, if the Sun shine very warm, upon the
first taking off the Glass, which I therefore call the humble Plant.
The other two, which do never fall, nor do any of their
branches flag and hang down, shut not their leaves, but upon
somewhat a hard stroke; the stalks seem to grow up from a root,
and appear more herbaceous, they are round and smooth, without
any prickle, the Sprouts from them have several pairs of sprigs,
with much less leaves then the other on them, and have on each
sprig generally seventeen pair.

Upon touching any of the sprigs with leaves on, all the leaves
on that sprig contracting themselves by pairs, joyned their upper
superficies close together.
Upon the dropping a drop of Aqua fortis on the sprig betwixt
the leaves, ff all the leaves above shut presently, those below by
pairs successively after, and by the lower leaves of the other
branches, ll, kk, &c. and so every pair successively, with some
little distance of time betwixt, to the top of each sprig, and so they
continu’d shut all the time we were there. But I returning the next
day, and several days since, found all the leaves dilated again on
two of the sprigs; but from ff, where the Aqua fortis had dropped
upwards, dead and withered; but those below on the same sprig,
green, and closing upon the touch, and are so to this day, August
14.
With a pair of Scissers, as suddenly as it could be done, one of
the leaves bb was clipped off in the middle, upon which that pair,
and the pair above, closed presently, after a little interval, dd, then
ee, and so the rest of the pairs, to the bottom of the sprig, and then
the motion began in the lower pairs, ll, on the other sprigs, and so
shut them by pairs upwards, though not with such distinct
distances.
Under a pretty large branch with its sprigs on, there lying a
large Shell betwixt two and three Inches below it, there was
rubbed on a strong scented oyl, after a little time all the leaves on
that sprig were shut, and so they continued all the time of our stay
there, but at my returne the next day, I found the position of the
Shell alter’d, and the leaves expanded as before, and closing upon
the touch.
Upon the application of the Sun-beams by a Burning-glass, the
more humble Plant fell, the other shut their leaves.
We could not so apply the smoak of Sulpher, as to have any
visible effect from that, at two or three times trial; but on another
trial, the smoak touching the leaves, it succeeded.

The humble Plant fell upon taking off the Glass wherewith it
was covered.
Cutting off one of the little Sprouts, two or three drops of
liquor were thrust out of the part from whence that was cut, very
cleer, and pellucid, of a bright greenish colour, tasting at first a
little bitterish, but after leaving a licorish-like taste in my mouth.
Since, going two or three times when it was cold, I took the
Glasses from the more humble Plant, and it did not fall as
formerly, but shut its leaves onely. But coming afterwards, when
the Sun shone very warm, as soon as it was taken off, it fell as
before.
Since I pluck’d off another sprig, whose leaves were all shut,
and had been so some time, thinking to observe the liquor should
come from that I had broken off, but finding none, though with
pressing, to come, I, as dexterously as I could, pull’d off one
whose leaves were expanded, and then had upon the shutting of
the leaves, a little of the mention’d liquor, from the end of the
sprig I had broken from the Plant. And this twice successively, as
often almost as I durst rob the Plant.
But my curiosity carrying me yet further, I cut off one of the
harder branches of the stronger Plant, and there came of the
liquor, both from that I had cut, and that I had cut it from, without
pressure.
Which made me think, that the motion of this Plant upon
touching, might be from this, that there being a constant
intercourse betwixt every part of this Plant and its root, either by
a circulation of this liquor, or a constant pressing of the subtiler
parts of it to every extremity of the Plant. Upon every pressure,
from whatsoever it proceeds, greater then that which keeps it up,
the subtile parts of this liquor are thrust downwards, towards its
articulations of the leaves, where, not having room presently to
get into the sprig, the little round pedunculus, from whence the
Spine and those oblique Fibres I mentioned rise, being dilated, the
Spine and Fibres (being continued from it) must be contracted

and shortned, and so draw the leaf upwards to joyn with its fellow
in the same condition with it self, where, being closed, they are
held together by the implications of the little whitish hair, as well
as by the still retreating liquor, which distending the Fibres that
are continued lower to the branch and root, shorten them above;
and when the liquor is so much forced from the Sprout, whose
Fibres are yet tender, and not able to support themselves, but by
that tensness which the liquor filling their interstices gives them,
the Sprout hangs and flags.
But, perhaps, he that had the ability and leisure to give you the
exact Anatomy of this pretty Plant, to shew you its Fibres, and
visible Canales, through which this fine liquor circulateth, or is
moved, and had the faculty of better and more copiously
expressing his Observations and conceptions, such a one would
easily from the motion of this liquor, solve all the Phænomena,
and would not fear to affirm, that it is no obscure sensation this
Plant hath. But I have said too much, I humbly submit, and am
ready to stand corrected.

I have not yet made so full and satisfactory Observations as I desire on
this Plant, which seems to be a Subject that will afford abundance of
information. But as farr as I have had opportunity to examine it, I have
discovered with my Microscope very curious structures and contrivances;
but designing much more accurate examinations and trials, both with my
Microscope, and otherwise, as soon as the season will permit, I shall not till
then add any thing of what I have already taken notice of; but as farr as I
have yet observ’d, I judge the motion of it to proceed from causes very
differing from those by which Gut-strings, or Lute-strings, the beard of a
wilde Oat, or the beard of the Seeds of Geranium, Moscatum, or Musk-
grass and other kinds of Cranes-bill, move themselves. Of which I shall
add more in the subsequent Observations on those bodies.

Observ. XIX. Of a Plant growing in the blighted or
yellow specks of Damask-rose-leaves, Bramble-
leaves, and some other kind of leaves.
I have for several years together, in the Moneths of June, July, August,
and September (when any of the green leaves of Roses begin to dry and
grow yellow) observ’d many of them, especially the leaves of the old
shrubs of Damask Roses, all bespecked with yellow stains; and the
undersides just against them, to have little yellow hillocks of a gummous
substance, and several of them to have small black spots in the midst of
those yellow ones, which, to the naked eye, appear’d no bigger then the
point of a Pin, or the smallest black spot or tittle of Ink one is able to make
with a very sharp pointed Pen.
Schem. 12.
Fig. 2.

Examining these with a Microscope, I was able plainly to distinguish, up
and down the surface, several small yellow knobs, of a kind of yellowish
red gummy substance, out of which I perceiv’d there sprung multitudes of
little cases or black bodies like Seed-cods, and those of them that were quite
without the hillock of Gumm, disclos’d themselves to grow out of it with a
small Straw-colour’d and transparent stem, the which seed and stem
appear’d very like those of common Moss (which I elsewhere describe) but
that they were abundantly less, many hundreds of them being not able to
equalize one single seed Cod of Moss.
I have often doubted whether they were the seed Cods of some little
Plant, or some kind of small Buds, or the Eggs of some very small Insect,
they appear’d of a dark brownish red, some almost quite black, and of a
Figure much resembling the seed-cod of Moss, but their stalks on which
they grew were of a very fine transparent substance, almost like the stalk of
mould, but that they seem’d somewhat more yellow.

That which makes me to suppose them to be Vegetables, is for that I
perceiv’d many of those hillocks bare or destitute, as if those bodies lay yet
conceal’d, as G. In others of them, they were just springing out of their
gummy hillocks, which all seem’d to shoot directly outwards, as at A. In
others, as at B, I found them just gotten out, with very little or no stalk, and
the Cods of an indifferent cize; but in others, as C, I found them begin to
have little short stalks, or stems; in others, as D, those stems were grown
bigger, and larger; and in others, as at E, F, H, I, K, L, &c. those stems and
Cods were grown a great deal bigger, and the stalks were more bulky about
the root, and very much taper’d towards the top, as at F and L is most
visible.
I did not find that any of them had any seed in them, or that any of them
were hollow, but as they grew bigger and bigger, I found those heads or
Cods begin to turn their tops towards their roots, in the same manner as I
had observ’d that of Moss to do; so that in all likelihood, Nature did intend
in that posture, what she does in the like seed-cods of greater bulk, that is,
that the seed, when ripe, should be shaken out and dispersed at the end of it,
as we find in Columbine Cods, and the like.
The whole Oval OOOO in the second Figure of the 12. Scheme
represents a small part of a Rose-leaf, about the bigness of the little Oval in
the hillock, C, marked with the Figure X. in which I have not particularly
observ’d all the other forms of the surface of the Rose-leaf, as being little to
my present purpose.
Now, if these Cods have a seed in them so proportion’d to the Cod, as
thole of Pinks, and Carnations, and Columbines, and the like, how
unimaginably small must each of those seeds necessarily be, for the whole
length of one of the largest of those Cods was not ¹⁄₅₀₀ part of an Inch; some
not above ¹⁄₁₀₀₀, and therefore certainly, very many thousand of them would
be unable to make a bulk that should be visible to the naked eye; and if each
of these contain the Rudiments of a young Plant of the same kind, what
must we say of the pores and constituent parts of that?
The generation of this Plant seems in part, ascribable to a kind of Mildew
or Blight, whereby the parts of the leaves grow scabby, or putrify’d, as it

were, so as that the moisture breaks out in little scabs or spots, which, as I
said before, look like little knobs of a red gummous substance.
From this putrify’d scab breaks out this little Vegetable; which may be
somewhat like a Mould or Moss; and may have its equivocal generation
much after the same manner as I have supposed Moss or Mould to have, and
to be a more simple and uncompounded kind of vegetation, which is set a
moving by the putrefactive and fermentative heat, joyn’d with that of the
ambient aerial, when (by the putrifaction and decay of some other parts of
the vegetable, that for a while staid its progress) it is unfetter’d and left at
liberty to move in its former course, but by reason of its regulators, moves
and acts after quite another manner then it did when a coagent in the more
compounded machine of the more perfect Vegetable.
And from this very same Principle, I imagine the Misleto of Oaks,
Thorns, Appletrees, and other Trees, to have its original: It seldom or never
growing on any of those Trees, till they begin to wax decrepid, and decay
with age, and are pester’d with many other infirmities.
Hither also may be referr’d those multitudes and varieties of Mushroms,
such as that, call’d Jews-ears, all sorts of gray and green Mosses, &c.
which infest all kind of Trees, shrubs, and the like, especially when they
come to any bigness. And this we see to be very much the method of Nature
throughout its operations, putrifactive Vegetables very often producing a
Vegetable of a much less compounded nature, and of a much inferiour tribe;
and putrefactive animal substances degenerating into some kind of animal
production of a much inferiour rank, and of a more simple nature.
Thus we find the humours and substances of the body, upon putrifaction,
to produce strange kinds of moving Vermine: the putrifaction of the slimes
and juices of the Stomack and Guts, produce Worms almost like Earth-
worms, the Wheals in childrens hands produce a little Worm, call’d a
Wheal-worm: The bloud and milk, and other humours, produce other kinds
of Worms, at least, if we may believe what is deliver’d to us by very famous
Authors; though, I confess, I have not yet been able to discover such my
self.
And whereas it may seem strange that Vinegar, Meal, musty Casks, &c.
are observ’d to breed their differing kinds of Insects, or living creatures,

whereas they being Vegetable substances, seem to be of an inferiour kind,
and so unable to produce a creature more noble, or of a more compounded
nature then they themselves are of, and so without some concurrent seminal
principle, may be thought utterly unfit for such an operation; I must add,
that we cannot presently positively say, there are no animal substances,
either mediately, as by the soil or fatning of the Plant from whence they
sprung, or more immediately, by the real mixture or composition of such
substances, join’d with them; or perchance some kind of Insect, in such
places where such kind of putrifying or fermenting bodies are, may, by a
certain instinct of nature, eject some sort of seminal principle, which
cooperating with various kinds of putrifying substances, may produce
various kinds of Insects, or Animate bodies: For we find in most sorts of
those lower degrees of Animate bodies, that the putrifying substances on
which these Eggs, Seeds, or seminal principles are cast by the Insect,
become, as it were, the Matrices or Wombs that conduce very much to their
generation, and may perchance also to their variation and alteration, much
after the same manner, as, by strange and unnatural copulations, several
new kinds of Animals are produc’d, as Mules, and the like, which are
usually call’d Monstrous, because a little unusual, though many of them
have all their principal parts as perfectly shap’d and adapted for their
peculiar uses, as any of the most perfect Animals. If therefore the putrifying
body, on which any kind of seminal or vital principle chances to be cast,
become somewhat more then meerly a nursing and fostering helper in the
generation and production of any kind of Animate body, the more neer it
approaches the true nature of a Womb, the more power will it have on the
by-blow it incloses. But of this somewhat more in the description of the
Water-gnat. Perhaps some more accurate Enquiries and Observations about
these matters might bring the Question to some certainty, which would be
of no small concern in Natural Philosophy.
But that putrifying animal substances may produce animals of an inferior
kind, I see not any so very great a difficulty, but that one may, without much
absurdity, admit: For as there may be multitudes of contrivances that go to
the making up of one compleat Animate body; so, That some of those
coadjutors, in the perfect existence and life of it, may be vitiated, and the
life of the whole destroyed, and yet several of the constituting contrivances
remain intire, I cannot think it beyond imagination or possibility; no more

then that a like accidental process, as I have elswhere hinted, may also be
supposed to explicate the method of Nature in the Metamorphosis of Plants.
And though the difference between a Plant and an Animal be very great, yet
I have not hitherto met with any so cogent an Argument, as to make me
positive in affirming these two to be altogether Heterogeneous and of quite
differing kinds of Nature: And besides, as there are many Zoophyts, and
sensitive Plants (divers of which I have seen, which are of a middle nature,
and seem to be Natures transition from one degree to another, which may be
observ’d in all her other passages, wherein she is very seldom observ’d to
leap from one step to another) so have we, in some Authors, Instances of
Plants turning into Animals, and Animals into Plants, and the like; and some
other very strange (because unheeded) proceedings of Nature; something of
which kind may be met with, in the description of the Water-Gnat, though it
be not altogether so direct to the present purpose.
But to refer this Discourse of Animals to their proper places, I shall add,
that though one should suppose, or it should be prov’d by Observations;
that several of these kinds of Plants are accidentally produc’d by a casual
putrifaction, I see not any great reason to question, but that,
notwithstanding its own production was as ’twere casual, yet it may
germinate and produce seed, and by it propagate its own, that is, a new
Species. For we do not know, but that the Omnipotent and All-wise Creator
might as directly design the structure of such a Vegetable, or such an
Animal to be produc’d out of such or such a putrifaction or change of this
or that body, towards the constitution or structure of which, he knew it
necessary, or thought it fit to make it an ingredient; as that the digestion or
moderate heating of an Egg, either by the Female, or the Sun, or the heat of
the Fire, or the like, should produce this or that Bird; or that Putrifactive
and warm steams should, out of the blowings, as they call them, that is, the
Eggs of a Flie, produce a living Magot, and that, by degrees, be turn’d into
an Aurelia, and that, by a longer and a proportion’d heat, be transmuted into
a Fly. Nor need we therefore to suppose it the more imperfect in its kind,
then the more compounded Vegetable or Animal of which it is a part; for he
might as compleatly furnish it with all kinds of contrivances necessary for
its own existence, and the propagation of its own Species, and yet make it a
part of a more compounded body: as a Clock-maker might make a Set of
Chimes to be a part of a Clock, and yet, when the watch part or striking part

are taken away, and the hindrances of its motion remov’d, this chiming part
may go as accurately, and strike its tune as exactly, as if it were still a part
of the compounded Automaton. So, though the original cause, or seminal
principle from which this minute Plant on Rose leaves did spring; were,
before the corruption caus’d by the Mill-dew, a component part of the leaf
on which it grew, and did serve as a coagent in the production and
constitution of it, yet might it be so consummate, as to produce a seed
which might have a power of propagating the same species: the works of
the Creator seeming of such an excellency, that though they are unable to
help to the perfecting of the more compounded existence of the greater
Plant or Animal, they may have notwithstanding an ability of acting singly
upon their own internal principle, so as to produce a Vegetable body, though
of a less compounded nature, and to proceed so farr in the method of other
Vegetables, as to bear flowers and seeds, which may be capable of
propagating the like. So that the little cases which appear to grow on the top
of the slender stalks, may, for ought I know, though I should suppose them
to spring from the perverting of the usual course of the parent Vegetable,
contain a seed, which, being scatter’d on other leaves of the same Plant,
may produce a Plant of much the same kind.
Nor are Damask-Rose leaves the onely leaves that produce these kinds of
Vegetable sproutings; for I have observ’d them also in several other kinds
of Rose leaves, and on the leaves of several sorts of Briers, and on Bramble
leaves they are oftentimes to be found in very great clusters; so that I have
found in one cluster, three, four, or five hundred of them, making a very
conspicuous black spot or scab on the back side of the leaf.

Observ. XX. Of blue Mould, and of the first
Principles of Vegetation arising from Putrefaction.
The Blue and White and several kinds of hairy mouldy spots, which are
observable upon divers kinds of putrify’d bodies, whether Animal
substances, or Vegetable, such as the skin, raw or dress’d, flesh, bloud,
humours, milk, green Cheese, &c. or rotten sappy Wood, or Herbs, Leaves,
Barks, Roots, &c. of Plants, are all of them nothing else but several kinds of
small and variously figur’d Mushroms, which, from convenient materials in
those putrifying bodies, are, by the concurrent heat of the Air, excited to a
certain kind of vegetation, which will not be unworthy our more serious
speculation and examination, as I shall by and by shew. But, first, I must
premise a short description of this Specimen, which I have added of this
Schem. 12.
Fig. 1. Tribe, in the first Figure of the XII. Scheme, which is nothing else but
the appearance of a small white spot of hairy mould, multitudes of which I
found to bespeck & whiten over the red covers of a small book, which, it
seems, were of Sheeps skin, that being more apt to gather mould, even in a
dry and clean room, then other leathers. These spots appear’d, through a
good Microscope, to be a very pretty shap’d Vegetative body, which, from
almost the same part of the Leather, shot out multitudes of small long
cylindrical and transparent stalks, not exactly streight, but a little bended
with the weight of a round and white knob that grew on the top of each of
them; many of these knobs I observ’d to be very round, and of a smooth
surface, such as A, A, &c. others smooth likewise, but a little oblong, as B;
several of them a little broken, or cloven with chops at the top, as C; others
flitter’d as ’twere, or flown all to pieces, as D, D. The whole substance of
these pretty bodies was of a very tender constitution, much like the
substance of the softer kind of common white Mushroms, for by touching
them with a Pin, I found them to be brused and torn; they seem’d each of
them to have a distinct root of their own; for though they grew neer together
in a cluster, yet I could perceive each stem to rise out of a distinct part or
pore of the Leather; some of these were small and short, as seeming to have
been but newly sprung up, of these the balls were for the most part round,

others were bigger, and taller, as being perhaps of a longer growth, and of
these, for the most part, the heads were broken, and some much wasted, as
E; what these heads contain’d I could not perceive; whether they were
knobs and flowers, or seed cases, I am not able to say, but they seem’d most
likely to be of the same nature with those that grow on Mushroms, which
they did, some of them, not a little resemble.
Both their smell and taste, which are active enough to make a sensible
impression upon those organs, are unpleasant and noisome.
I could not find that they would so quickly be destroy’d by the actual
flame of a Candle, as at first sight of them I conceived they would be, but
they remain’d intire after I had past that part of the Leather on which they
stuck three or four times through the flame of a Candle; so that, it seems
they are not very apt to take fire, no more then the common white
Mushroms are when they are sappy.
There are a multitude of other shapes, of which these Microscopical
Mushroms are figur’d, which would have been a long Work to have
described, and would not have suited so well with my design in this
Treatise, onely, amongst the rest, I must not forget to take notice of one that
was a little like to, or resembled, a Spunge, consisting of a multitude of
little Ramifications almost as that body does, which indeed seems to be a
kind of Water-Mushrom, of a very pretty texture, as I else-where manifest.
And a second, which I must not omit, because often mingled, and neer
adjoining to these I have describ’d, and this appear’d much like a Thicket of
bushes, or brambles, very much branch’d, and extended, some of them, to a
great length, in proportion to their Diameter, like creeping brambles.
The manner of the growth and formation of this kind of Vegetable, is the
third head of Enquiry, which, had I time, I should follow: the figure and
method of Generation in this concrete seeming to me, next after the Enquiry
into the formation, figuration; or chrystalization of Salts, to be the most
simple, plain, and easie; and it seems to be a medium through which he
must necessarily pass, that would with any likelihood investigate the forma
informans of Vegetables: for as I think that he shall find it a very difficult
task, who undertakes to discover the form of Saline crystallizations, without
the consideration and prescience of the nature and reason of a Globular

form, and as difficult to explicate this configuration of Mushroms, without
the previous consideration of the form of Salts; so will the enquiry into the
forms of Vegetables be no less, if not much more difficult, without the fore-
knowledge of the forms of Mushroms, these several Enquiries having no
less dependance one upon another then any select number of Propositions in
Mathematical Elements may be made to have.
Nor do I imagine that the skips from the one to another will be found
very great, if beginning from fluidity, or body without any form, we
descend gradually, till we arrive at the highest form of a bruite Animal’s
Soul, making the steps or foundations of our Enquiry, Fluidity,
Orbiculation, Fixation, Angulization, or Crystallization Germination or
Ebullition, Vegetation, Plantanimation, Animation, Sensation, Imagination.
Now, that we may the better proceed in our Enquiry, It will be requisite to
consider:
First, that Mould and Mushroms require no seminal property, but the
former may be produc’d at any time from any kind of putrifying Animal, or
Vegetable Substance, as Flesh, &c. kept moist and warm, and the latter, if
what Mathiolus relates be true, of making them by Art, are as much within
our command, of which Matter take the Epitomie which Mr. Parkinson has
deliver’d in his Herbal, in his Chapter of Mushroms, because I have not
Mathiolus now by me: Unto these Mushroms (saith he) may also be
adjoyn’d those which are made of Art (whereof Mathiolus makes mention)
that grow naturally among certain stones in Naples, and that the stones
being digg’d up, and carried to Rome, and other places, where they set
them in their Wine Cellars, covering them with a little Earth, and sprinkling
a little warm water thereon, would within four days produce Mushroms fit
to be eaten, at what time one will: As also that Mushroms may be made to
grow at the foot of a wilde Poplar Tree, within four days after, warm water
wherein some leaves have been dissolv’d shall be pour’d into the Root
(which must be slit) and the stock above ground.
Next, that as Mushroms may be generated without seed, so does it not
appear that they have any such thing as seed in any part of them; for having
considered several kinds of them, I could never find any thing in them that I
could with any probability ghess to be the seed of it, so that it does not as

yet appear (that I know of) that Mushroms may be generated from a seed,
but they rather seem to depend merely upon a convenient constitution of the
matter out of which they are made, and a concurrence of either natural or
artificial heat.
Thirdly, that by several bodies (as Salts and Metals both in Water and in
the air, and by several kinds of sublimations in the Air) actuated and guided
with a congruous heat, there may be produc’d several kinds of bodies as
curiously, if not of a more compos’d Figure; several kinds of rising or
Ebulliating Figures seem to manifest; as witness the shooting in the
Rectification of spirits of Urine, Hart-horn, Bloud, &c. witness also the
curious branches of evaporated dissolutions, some of them against the sides
of the containing Jar: others standing up, or growing an end, out of the
bottom, of which I have taken notice of a very great variety. But above all
the rest, it is a very pretty kind of Germination which is afforded us in the
Silver Tree, the manner of making which with Mercury and Silver, is well
known to the Chymists, in which there is an Ebullition or Germination, very
much like this of Mushroms, if I have been rightly inform’d of it.
Fourthly, I have very often taken notice of, and also observ’d with a
Microscope, certain excrescencies or Ebullitions in the snuff of a Candle,
which, partly from the sticking of the smoaky particles as they are carryed
upwards by the current of the rarify’d Air and flame, and partly also from a
kind of Germination or Ebullition of some actuated unctuous parts which
creep along and filter through some small string of the Week, are formed
into pretty round and uniform heads, very much resembling the form of
hooded Mushroms, which, being by any means expos’d to the fresh Air, or
that air which encompasses the flame, they are presently lick’d up and
devour’d by it, and vanish.
The reason of which Phænomenon seems to me, to be no other then this:
That when a convenient thread of the Week is so bent out by the sides of
the snuff that are about half an Inch or more, remov’d above the bottom, or
lowest part of the flame, and that this part be wholly included in the flame;
the Oyl (for the reason of filtration, which I have elsewhere rendred) being
continualy driven up the snuff is driven likewise into this ragged bended-
end, and this being remov’d a good distance, as half an Inch or more, above

the bottom of the flame, the parts of the air that passes by it, are already,
almost satiated with the dissolution of the boiling unctuous steams that
issued out below, and therefore are not onely glutted, that is, can dissolve
no more then what they are already acting upon, but they carry up with
them abundance of unctuous and sooty particles, which meeting with that
rag of the Week, that is plentifully fill’d with Oyl, and onely spends it as
fast as it evaporates, and not at all by dissolution or burning, by means of
these steamy parts of the filtrated Oyl issuing out at the sides of this ragg,
and being inclos’d with an air that is already satiated and cannot prey upon
them nor burn them, the ascending sooty particles are stay’d about it and
fix’d, so as that about the end of that ragg or filament of the snuff, whence
the greatest part of the steams issue, there is conglobated or fix’d a round
and pretty uniform cap, much resembling the head of a Mushrom, which, if
it be of any great bigness, you may observe that its underside will be bigger
then that which is above the ragg or stem of it; for the Oyl that is brought
into it by filtration, being by the bulk of the cap a little shelter’d from the
heat of the flame, does by that means issue as much out beneath from the
stalk or downwards, as it does upwards, and by reason of the great access of
the adventitious smoak from beneath, it increases most that way. That this
may be the true reason of this Phænomenon, I could produce many
Arguments and Experiments to make it probable: As,
First, that the Filtration carries the Oyl to the top of the Week, at least as
high as these raggs, is visible to one that will observe the snuff of a burning
Candle with a Microscope, where he may see an Ebullition or bubbling of
the Oyl, as high as the snuff looks black.
Next, that it does steam away more then burn; I could tell you of the dim
burning of a Candle, the longer the snuff be which arises from the
abundance of vapours out of the higher parts of it.
And, thirdly, that in the middle of the flame of the Candle, neer the top of
the snuff, the fire or dissolving principle is nothing neer so strong, as neer
the bottom and out edges of the flame, which may be observ’d by the
burning asunder of a thread, that will first break in those parts that the edges
of the flame touch, and not in the middle.

And I could add several Observables that I have taken notice of in the
flame of a Lamp actuated with Bellows, and very many others that confirm
me in my opinion, but that it is not so much to my present purpose, which is
onely to consider this concreet in the snuff of a Candle, so farr as it has any
resemblance of a Mushrom, to the consideration of which, that I may return,
I say, we may also observe:
In the fifth place, that the droppings or trillings of Lapidescent waters in
Vaults under ground, seem to constitute a kind of petrify’d body, form’d
almost like some kind of Mushroms inverted, in so much that I have seen
some knobb’d a little at the lower end, though for the most part, indeed they
are otherwise shap’d, and taper’d towards the end; the generation of which
seems to be from no other reason but this, that the water by soaking through
the earth and Lime (for I ghess that substance to add much to it petrifying
quality) does so impregnate it self with stony particles, that hanging in
drops in the roof of the Vault, by reason that the soaking of the water is but
slow, it becomes expos’d to the Air, and thereby the outward part of the
drop by degrees grows hard, by reason that the water gradually evaporating
the stony particles neer the outsides of the drop begin to touch, and by
degrees, to dry and grow closer together, and at length constitute a crust or
shell about the drop; and this soaking by degrees, being more and more
supply’d, the drop grows longer and longer, and the sides harden thicker
and thicker into a Quill or Cane, and at length, that hollow or pith becomes
almost stop’d up, and solid: afterwards the soaking of the petrifying water,
finding no longer a passage through the middle, bursts out, and trickles
down the outside, and as the water evaporates, leaves new superinduc’d
shells, which more and more swell the bulk of those Iceicles, and because
of the great supply from the Vault, of petrifying wafer, those bodies grow
bigger and bigger next to the Vault, and taper or sharpen towards the point;
for the access from the arch of the Vault being but very slow, and
consequently the water being spread very thinly over the surface of the
Iceicle, the water begins to settle before it can reach to the bottom, or corner
end of it; whence, if you break one of these, you would almost imagine it a
stick of Wood petrify’d, it having so pretty a resemblance of pith and grain,
and if you look on the outside of a piece, or of one whole, you would think
no less, both from its vegetable roundness and tapering form; but whereas

all Vegetables are observ’d to shoot and grow perpendicularly upwards, this
does shoot or propend directly downwards.
By which last Observables, we see that there may be a very pretty body
shap’d and concreeted by Mechanical principles, without the least shew or
probability of any other seminal formatrix.
And since we find that the great reason of the Phænomena of this pretty
petrifaction, are to be reduc’d from the gravity of a fluid and pretty volatil
body impregnated with stony particles, why may not the Phænomena of
Ebullition or Germination be in part possibly enough deduc’d from the
levity of an impregnated liquor, which therefore perpendicularly ascending
by degrees, evaporates and leaves the more solid and fix’d parts behind in
the form of a Mushrom, which is yet further diversify’d and specificated by
the forms of the parts that impregnated the liquor, and compose or help to
constitute the Mushrom.
That the foremention’d Figures of growing Salts, and the Silver Tree, are
from this principle, I could very easily manifest, but that I have not now a
convenient opportunity of following it, nor have I made a sufficient number
of Experiments and Observations to propound, explicate, and prove so
usefull a Theory as this of Mushroms: for, though the contrary principle to
that of petrify’d Iceicles may be in part a cause, yet I cannot but think, that
there is somewhat a more complicated cause, though yet Mechanical, and
possible to be explain’d.
We therefore have further to enquire of it, what makes it to be such a
liquor, and to ascend, whether the heat of the Sun and Air, or whether that
firmentiation and putrifaction, or both together; as also whether there be not
a third or fourth; whether a Saline principle be not a considerable agent in
this business also as well as heat; whether also a fixation, precipitation or
settling of certain parts out of the aerial menstruum may not be also a
considerable coadjutor in the business. Since we find that many pretty
beards or stiriæ of the particles of Silver may be precipitated upon a piece
of Brass put into a solution of Silver very much diluted with fair water,
which look not unlike a kind of mould or hoar upon that piece of metal; and
the hoar frost looks like a kind of mould; and whether there may not be
several others that do concurr to the production of a Mushrom, having not

yet had sufficient time to prosecute according to my desires, I must refer
this to a better opportunity of my own, or leave and recommend it to the
more diligent enquiry and examination of such as can be masters both of
leisure and conveniencies for such an Enquiry.
And in the mean time, I must conclude, that as far as I have been able to
look into the nature of this Primary kind of life and vegetation, I cannot find
the least probable argument to perswade me there is any other concurrent
cause then such as is purely Mechanical, and that the effects or productions
are as necessary upon the concurrence of those causes as that a Ship, when
the Sails are hoist up, and the Rudder is set to such a position, should, when
the Wind blows, be mov’d in such a way or course to that or t’other place;
Or, as that the brused Watch, which I mention in the description of Moss,
should, when those parts which hindred its motion were fallen away, begin
to move, but after quite another manner then it did before.

Observ. XXI. Of Moss, and several other small
vegetative Substances.
Moss is a Plant, that the wisest of Kings thought neither unworthy his
speculation, nor his Pen, and though amongst Plants it be in bulk one of the
smallest, yet it is not the least considerable: For, as to its shape, it may
compare for the beauty of it with any Plant that grows, and bears a much
bigger breadth; it has a root almost like a seedy Parsnep, furnish’d with
small strings and suckers, which are all of them finely branch’d, like those
of the roots of much bigger Vegetables; out of this springs the stem or body
of the Plant, which is somewhat Quadrangular, rather then Cylindrical,
most curiously fluted or strung with small creases, which run, for the most
part, parallel the whole stem; on the sides of this are close and thick set, a
multitude of fair, large, well-shap’d leaves, some of them of a rounder,
others of a longer shape, according as they are younger or older when
pluck’d; as I ghess by this, that those Plants that had the stalks growing
from the top of them, had their leaves of a much longer shape, all the
surface of each side of which, is curiously cover’d with a multitude of little
oblong transparent bodies, in the manner as you see Schem. 13.
Fig. B. it express’d in the leaf B, in the XIII. Scheme.

This Plant, when young and springing up, does much resemble a
Housleek, having thick leaves, almost like that, and seems to be somwhat of
kin to it in other particulars; also from the top of the leaves, there shoots out
a small white and transparent hair, or thorn: This stem, in time, come to
shoot out into a long, round and even stalk, which by cutting transversly,
when dry, I manifestly found to be a stiff, hard, and hollow Cane, or Reed,
without any kind of knot, or stop, from its bottom, where the leaves
encompass’d it, to the top, on which there grows a large seed case, A,
cover’d with a thin, and more whitish skin, B, terminated in a long thorny
top, which at first covers all the Case, and by degrees, as that swells, the
skin cleaves, and at length falls off, with its thorny top and all (which is a
part of it) and leaves the seed Case to ripen, and by degrees, to shatter out
its seed at a place underneath this cap, B, which before the seed is ripe,

appears like a flat barr’d button, without any hole in the middle; but as it
ripens, the button grows bigger, and a hole appears in the middle of it, E,
out of which, in all probability, the seed falls: For as it ripens by a provision
of Nature, that end of this Case turns downward after the same manner as
the ears of Wheat and Barley usually do; and opening several of these dry
red Cases, F, I found them to be quite hollow, without anything at all in
them; whereas when I cut them asunder with a sharp Pen-knife when green,
I found in the middle of this great Case, another smaller round Case,
between which two, the interstices were fill’d with multitudes of stringie
fibres, which seem’d to suspend the lesser Case in the middle of the other,
which (as farr as I was able to discern) seem’d full of exceeding small white
seeds, much like the seed-bagg in the knop of a Carnation, after the flowers
have been two or three days, or a week, fallen off; but this I could not so
perfectly discern, and therefore cannot positively affirm it.
After the seed was fallen away, I found both the Case, Stalk, and Plant,
all grow red and wither, and from other parts of the root continually to
spring new branches or slips, which by degrees increased, and grew as bigg
as the former, seeded, ripen’d, shatter’d, and wither’d.
I could not find that it observ’d any particular seasons for these several
kinds of growth, but rather found it to be springing, mature, ripe, seedy, and
wither’d at all times of the year; But I found it most to flourish and increase
in warm and moist weather.
It gathers its nourishments, for the most part, out of some Lapidescent, or
other substance corrupted or chang’d from its former texture, or substantial
form; for I have found it to grow on the rotten parts of Stone, of Bricks, of
Wood, of Bones, of Leather, &c.
It oft grows on the barks of several Trees, spreading it self, sometimes
from the ground upwards, and sometimes from some chink or cleft of the
bark of the Tree, which has some putrify’d substance in it, but this seems of
a distinct kind from that which I observ’d to grow on putrify’d inanimate
bodies, and rotten earth.
There are also great varieties of other kinds of Mosses, which grow on
Trees, and several other Plants, of which I shall here make no mention, nor

of the Moss growing on the skull of a dead man, which much resembles that
of Trees.
Whether this Plant does sometimes originally spring or rise out of
corruption, without any disseminated seed, I have not yet made trials
enough to be very much, either positive or negative; for as it seems very
hard to conceive how the seed should be generally dispers’d into all parts
where there is a corruption begun, unless we may rationally suppose, that
this seed being so exceeding small, and consequently exceeding light, is
thereby taken up, and carried to and fro in the Air into every place, and by
the falling drops of rain is wash’d down out of it, and so dispers’d into all
places, and there onely takes root and propagates, where it finds a
convenient soil or matrix for it to thrive in; so if we will have it to proceed
from corruption, it is not less difficult to conceive,
First, how the corruption of any Vegetable, much less of any Stone or
Brick, should be the Parent of so curiously figur’d, and so perfect a Plant as
this is. But here indeed, I cannot but add, that it seems rather to be a product
of the Rain in those bodies where it is stay’d, then of the very bodies
themselves, since I have found it growing on Marble, and Flint, but always
the Microscope, if not the naked eye, would discover some little hole of
Dirt in which it was rooted.
Next, how the corruption of each of those exceedingly differing bodies
should all conspire to the production of the same Plant, that is, that Stones,
Bricks, Wood, or vegetable substances, and Bones, Leather, Horns, or
animate substances, unless we may with some plausibleness say, that Air
and Water are the coadjutors, or menstruums, all kinds of putrifactions, and
that thereby the bodies (though whil’st they retain’d their substantial forms,
were of exceeding differing natures, yet) since they are dissolv’d and mixt
into another, they may be very Homogeneous, they being almost resolv’d
again into Air, Water, and Earth; retaining, perhaps, one part of their
vegetative faculty yet entire, which meeting with congruous assistants, such
as the heat of the Air, and the fluidity of the Water, and such like coadjutors
and conveniences, acquires a certain vegetation for a time, wholly differing
perhaps from that kind of vegetation it had before.
To explain my meaning a little better by a gross Similitude:

Suppose a curious piece of Clock-work, that had had several motions and
contrivances in it, which, when in order, would all have mov’d in their
design’d methods and Periods. We will further suppose, by some means,
that this Clock comes to be broken, brused, or otherwise disordered, so that
several parts of it being dislocated, are impeded, and so stand still, and not
onely hinder its own progressive motion, and produce not the effect which
they were design’d for, but because the other parts also have a dependence
upon them, put a stop to their motion likewise; and so the whole Instrument
becomes unserviceable, and not fit for any use. This Instrument afterwards,
by some shaking and tumbling, and throwing up and down, comes to have
several of its parts shaken out, and several of its curious motions, and
contrivances, and particles all fallen asunder; here a Pin falls out, and there
a Pillar, and here a Wheel, and there a Hammer, and a Spring, and the like,
and among the rest, away falls those parts also which were brused and
disorder’d, and had all this while impeded the motion of all the rest;
hereupon several of those other motions that yet remain, whole springs
were not quite run down, being now at liberty, begin each of them to move,
thus or thus, but quite after another method then before, there being many
regulating parts and the like, fallen away and lost. Upon this, the Owner,
who chances to hear and observe some of these effects, being ignorant of
the Watch-makers Art, wonders what is betid his Clock, and presently
imagines that some Artist has been at work, and has set his Clock in order,
and made a new kind of Instrument of it, but upon examining
circumstances, he finds there was no such matter, but that the casual
slipping out of a Pin had made several parts of his Clock fall to pieces, and
that thereby the obstacle that all this while hindred his Clock, together with
other usefull parts were fallen out, and so his Clock was set at liberty. And
upon winding up those springs again when run down, he finds his Clock to
go, but quite after another manner then it was wont heretofore.
And thus may it be perhaps in the business of Moss, and Mould, and
Mushroms, and several other spontaneous kinds of vegetations, which may
be caus’d by a vegetative principle, which was a coadjutor to the life and
growth of the greater Vegetable, and was by the destroying of the life of it
stopt and impeded in performing its office; but afterwards, upon a further
corruption of several parts that had all the while impeded it, the heat of the
Sun winding up, as it were, the spring, sets it again into a vegetative

motion, and this being single, and not at all regulated as it was before (when
a part of that greater machine the pristine vegetable) is mov’d after quite a
differing manner, and produces effects very differing from those it did
before.
But this I propound onely as a conjecture, not that I am more enclin’d to
this Hypothesis then the seminal, which upon good reason I ghess to be
Mechanical also, as I may elsewhere more fully shew: But because I may,
by this, hint a possible way how this appearance may be solv’d; supposing
we should be driven to confess from certain Experiments and Observations
made, that such or such Vegetables were produc’d out of the corruption of
another, without any concurrent seminal principle (as I have given some
reason to suppose, in the description of a Microscopical Mushrome)
without derogating at all from the infinite wisdom of the Creator. For this
accidental production, as I may call it, does manifest as much, if not very
much more, of the excellency of his contrivance as any thing in the more
perfect vegetative bodies of the world, even as the accidental motion of the
Automaton does make the owner see, that there was much more contrivance
in it then at first he imagin’d. But of this I have added more in the
description of Mould, and the Vegetables on Rose leaves, &c. those being
much more likely to have their original from such a cause then this which I
Schem. 13.. have here described, in the 13. Scheme, which indeed I cannot
conceive otherwise of, then as of a most perfect Vegetable, wanting nothing
of the perfections of the most conspicuous and vastest Vegetables of the
world, and to be of a rank so high, as that it may very properly be reckon’d
with the tall Cedar of Lebanon, as that Kingly Botanist has done.
We know there may be as much curiosity of contrivance, and excellency
of form in a very small Pocket-clock, that takes not up an Inch square of
room, as there may be in a Church-clock that fills a whole room; And I
know not whether all the contrivances and Mechanisms requisite to a
perfect Vegetable, may not be crowded into an exceedingly less room then
this of Moss, as I have heard of a striking Watch so small, that it serv’d for a
Pendant in a Ladies ear; and I have already given you the description of a
Plant growing on Rose leaves, that is abundantly smaller then Moss;
insomuch, that neer 1000. of them would hardly make the bigness of one
single Plant of Moss. And by comparing the bulk of Moss, with the bulk of
the biggest kind of Vegetable we meet with in Story (of which kind we find

in some hotter climates, as Guine, and Brasile, the stock or body of some
Trees to be twenty foot in Diameter, whereas the body or stem of Moss, for
the most part, is not above one sixtieth part of an Inch) we shall find that the
bulk of the one will exceed the bulk of the other, no less then 2985984
Millions, or 2985984000000, and supposing the production on a Rose leaf
to be a Plant, we shall have of those Indian Plants to exceed a production of
the same Vegetable kingdom no less then 1000 times the former number; so
prodigiously various are the works of the Creator, and so All-sufficient is he
to perform what to man would seem unpossible, they being both alike easie
to him, even as one day, and a thousand years are to him as one and the
same time.
I have taken notice of such an infinite variety of those smaller kinds of
vegetations, that should I have described every one of them, they would
almost have fill’d a Volume, and prov’d bigg enough to have made a new
Herbal, such multitudes are there to be found in moist hot weather,
especially in the Summer time, on all kind of putrifying substances, which,
whether they do more properly belong to the Classis of Mushrooms, or
Moulds, or Mosses, I shall not now dispute, there being some that seem
more properly of one kind, others of another, their colours and magnitudes
being as much differing as their Figures and substances.
Nay, I have observ’d, that putting fair Water (whether Rain-water or
Pump-water, or May-dew or Snow-water, it was almost all one) I have often
observ’d, I say, that this Water would, with a little standing, tarnish and
cover all about the sides of the Glass that lay under water, with a lovely
green; but though I have often endeavour’d to discover with my Microscope
whether this green were like Moss, or long striped Sea-weed, or any other
peculiar form, yet so ill and imperfect are our Microscopes, that I could not
certainly discriminate any.
Growing Trees also, and any kinds of Woods, Stones, Bones, &c. that
have been long expos’d to the Air and Rain, will be all over cover’d with a
greenish scurff, which will very much foul and green any kind of cloaths
that are rubb’d against it; viewing this, I could not certainly perceive in
many parts of it any determinate form, though in many I could perceive a
Bed as ’twere of young Moss, but in other parts it look’d almost like green
bushes, and very confus’d, but always of what ever irregular Figures the

parts appear’d of, they were always green, and seem’d to be either some
Vegetable, or to have some vegetating principle.

Observ. XXII. Of common Sponges, and several
other Spongie fibrous bodies.
A Sponge is commonly reckon’d among the Zoophyts, or Plant Animals;
and the texture of it, which the Microscope discovers, seems to confirm it;
for it is of a form whereof I never observ’d any other Vegetable, and indeed,
it seems impossible that any should be of it, for it consists of an infinite
number of small short fibres, or nervous parts, much of the same bigness,
curiously jointed or contex’d together in the form of a Net, as is more
plainly manifest by the little Draught which I have added, in the third
Figure of the IX. Scheme, of a piece of it, which Schem. 9.
Fig. 3. you may perceive represents a confus’d heap of the fibrous parts
curiously jointed and implicated. The joints are, for the most part, where
three fibres onely meet, for I have very seldom met with any that had four.
At these joints there is no one of the three that seems to be the stock
whereon the other grow, but each of the fibres are, for the most part, of an
equal bigness, and seem each of them to have an equal share in the joint;
the fibres are all of them much about the same bigness, not smaller towards
the top of the Sponge, and bigger neerer the bottom or root, as is usuall in
Plants, the length of each between the joints, is very irregular and different;
the distance between some two joints, being ten or twelve times more then
between some others.
Nor are the joints regular, and of an equitriagonal Figure, but, for the
most part, the three fibres so meet, that they compose three angles very
differing all of them from one another.
The meshes likewise, and holes of this reticulated body, are not less
various and irregular: some bilateral, others trilateral, and quadrilateral
Figures; nay, I have observ’d some meshes to have 5, 6, 7, 8, or 9. sides,
and some to have onely one, so exceeding various is the Lusus Naturæ in
this body.

As to the outward appearance of this Vegetative body, they are so usuall
everywhere, that I need not describe them, consisting of a soft and porous
substance, representing a Lock, sometimes a fleece of Wool; but it has
besides these small microscopical pores which lie between the fibres, a
multitude of round pores or holes, which, from the top of it, pierce into the
body, and sometimes go quite through to the bottom.
I have observ’d many of these Sponges, to have included likewise in the
midst of their fibrous contextures, pretty large friable stones, which must
either have been inclos’d whil’st this Vegetable was in formation, or
generated in those places after it was perfectly shap’d. The later of which
seems the more improbable, because I did not find that any of these stony
substances were perforated with the fibres of the Sponge.
I have never seen nor been enform’d of the true manner of the growing of
Sponges on the Rock; whether they are found to increase from little to
great, like Vegetables, that is, part after part, or like Animals, all parts
equally growing together; or whether they be matrices or feed-baggs of any
kind of Fishes, or some kind of watry Insect; or whether they are at any
times more soft and tender, or of another nature and texture, which things, if
I knew how, I should much desire to be informed of: but from a cursory
view that I at first made with my Microscope, and some other trials, I
supposed it to be some Animal substance cast out, and fastned upon the
Rocks in the form of a froth, or congeries of bubbles, like that which I have
often observ’d on Rosemary, and other Plants (wherein is included a little
Insect) that all the little films which divide these bubbles one from another,
did presently, almost after the substance began to grow a little harder, break,
and leave onely the thread behind, which might be, as ’twere, the angle or
thread between the bubbles, that the great holes or pores observable in these
Sponges were made by the eruption of the included Heterogeneous
substance (whether air, or some other body, for many other fluid bodies will
do the same thing) which breaking out of the lesser, were collected into
very large bubbles, and so might make their way out of the Sponge, and in
their passage might leave a round cavity; and if it were large, might carry
up with it the adjacent bubbles, which may be perceiv’d at the outside of the
Sponge, if it be first throughly wetted, and sufferr’d to plump itself into its
natural form, or be then wrung dry, and suffer’d to expand it self again,
which it will freely do whil’st moist: for when it has thus plump’d it self

into its natural shape and dimensions, ’tis obvious enough that the mouths
of the larger holes have a kind of lip or rising round about them, but the
other smaller pores have little or none. It may further be found, that each of
these great pores has many other small pores below, that are united unto it,
and help to constitute it, almost like so many rivulets or small streams that
contribute to the maintenance of a large River. Nor from this Hypothesis
would it have been difficult to explicate, how those little branches of Coral,
smal Stones, shells, and the like, come to be included by these frothy
bodies: But this indeed was but a conjecture; and upon a more accurate
enquiry into the form of it with the Microscope, it seems not to be the true
origine of them; for whereas Sponges have onely three arms which join
together at each knot, if they had been generated from bubbles they must
have had four.
But that they are Animal Substances, the Chymical examination of them
seems to manifest, they affording a volatil Salt and spirit, like Harts-Horn,
as does also their great strength and toughness, and their smell when burn’d
in the Fire or a Candle, which has a kind of fleshy sent, not much unlike to
hair. And having since examin’d several Authors concerning them, among
others; I find this account given by Bellonius, in the XI. Chap. of his 2d
Book, De Aquatilibus. Spongiæ recentes, says he, à siccis longe diversæ,
scopulis aquæ marinæ ad duos vel tres cubitos, nonnunquam quatuor
tantum digitos immersis, ut fungi arboribus adhærent, sordido quodam
succo aut mucosa potius sanie ræfertæ, usque adeò fœtida, ut vel eminus
nauseam excitet, continetur autem iis cavernis, quas inanes in siccis & lotis
Spongiis cernimus: Putris pulmonis modo nigræ conspiciuntur, verùm quæ
in sublimi aquæ nascuntur multo magis opaca nigredine suffusæ sunt.
Vivere quidem Spongias adhærendo Aristoteles censet: absolute vero
minime: sensumque aliquem habere, vel eo argumento (inquit) credantur,
quod difficillime abstrahantur, nisi clanculum agatur: Atq; ad avulsoris
accessum ita contrahantur, ut eas evellere difficile sit, quod idem etiam
faciunt quoties flatus tempestatésque urgent. Puto autem illis succum
sordidum quem supra diximus carnis loco à natura attributum fuisse: atque
meatibus latioribus tanquam intestinis aut interaneis uti. Cæterum pars ea
quæ Spongiæ cautibus adhærent est tanquam folii petiolus, à quo veluti
collum quoddam gracile incipit: quod deinde in latitudinem diffusum capitis
globum facit. Recentibus nihil est fistulosum, hæsitantque tanquam

radicibus. Superne omnes propemodum meatus concreti latent: inferne verò
quaterni aut quini patent, per quos eas sugere existimamus. From which
Description, they seem to be a kind of Plant-Animal that adheres to a Rock,
and these small fibres or threads which we have described, seem to have
been the Vessels which (’tis very probable) were very much bigger whil’st
the Interstitia were fill’d (as he affirms) with a mucous, pulpy or fleshy
substance; but upon the drying were shrunk into the bigness they now
appear.
The texture of it is such, that I have not yet met with any other body in
the world that has the like, but onely one of a larger sort of Sponge (which
is preserv’d in the Museum Harveanum belonging to the most Illustrious
and most learned Society of the Physicians of London) which is of a
horney, or rather of a petrify’d substance. And of this indeed, the texture
and make is exactly the same with common Sponges, but onely that both
the holes and the fibres, or texture of it is exceedingly much bigger, for
some of the holes were above an Inch and half over, and the fibres and
texture of it was bigg enough to be distinguished easily with ones eye, but
conspicuously with an ordinary single Microscope. And these indeed,
seem’d to have been the habitation of some Animal; and examining
Aristotle, I find a very consonant account hereunto, namely, that he had
known a certain little Animal, call’d Pinnothera, like a Spider, to be bred in
those caverns of a Sponge, from within which, by opening and closing
those holes, he insnares and catches the little Fishes; and in another place he
says, That ’tis very confidently reported, that there are certain Moths or
Worms that reside in the cavities of a Sponge, and are there nourished:
Notwithstanding all which Histories, I think it well worth the enquiring into
the History and nature of a Sponge, it seeming to promise some information
of the Vessels in Animal substances, which (by reason of the solidity of the
interserted flesh that is not easily remov’d, without destroying also those
interspers’d Vessels) are hitherto undiscover’d; whereas here in a Sponge,
the Parenchyma, it seems, is but a kind of mucous gelly, which is very
easily and clearly wash’d away.
The reason that makes me imagine, that there may probably be some
such texture in Animal substances, is, that examining the texture of the
filaments of tann’d Leather, I find it to be much of the same nature and
strength of a Sponge; and with my Microscope, I have observ’d many such

joints and knobs, as I have described in Sponges, the fibres also in the
hollow of several sorts of Bones, after the Marrow has been remov’d, I have
found somewhat to resemble this texture, though, I confess, I never yet
found any texture exactly the same, nor any for curiosity comparable to it.
The filaments of it are much smaller then those of Silk, and through the
Microscope appear very neer as transparent, nay, some parts of them I have
observ’d much more.
Having examin’d also several kinds of Mushroms, I finde their texture to
be somewhat of this kind, that is, to consist of an infinite company of small
filaments, every way contex’d and woven together, so as to make a kind of
cloth, and more particularly, examining a piece of Touch-wood (which is a
kind Jews-ear, or Mushrom, growing here in England also, on several sorts
of Trees, such as Elders, Maples, Willows, &c. and is commonly call’d by
the name of Spunk; but that we meet with to be sold in Shops, is brought
from beyond Seas) I found it to be made of an exceeding delicate texture:
For the substance of it feels, and looks to the naked eye, and may be
stretch’d any way, exactly like a very fine piece of Chamois Leather, or
wash’d Leather, but it is of somewhat a browner hew, and nothing neer so
strong; but examining it with my Microscope, I found it of somewhat
another make then any kind of Leather; for whereas both Chamois, and all
other kinds of Leather I have yet view’d, consist of an infinite company of
filaments, somewhat like bushes interwoven one within another, that is, of
bigger parts or stems, as it were, and smaller branchings that grow out of
them; or like a heap of Ropes ends, where each of the larger Ropes by
degrees seem to split or untwist, into many smaller Cords, and each of those
Cords into smaller Lines, and those Lines into Threads, &c. and these
strangely intangled, or interwoven one within another: The texture of this
Touch-wood seems more like that of a Lock or a Fleece of Wool, for it
consists of an infinite number of small filaments, all of them, as farr as I
could perceive, of the same bigness like those of a Sponge, but that the
filaments of this were not a twentieth part of the bigness of those of a
Sponge; and I could not so plainly perceive their joints, or their manner of
interweaving, though, as farr as I was able to discern with that Microscope I
had, I suppose it to have some kind of resemblance, but the joints are
nothing neer so thick, nor without much trouble visible.

The filaments I could plainly enough perceive to be even, round,
cylindrical, transparent bodies, and to cross each other every way, that is,
there were not more seem’d to lie horizontally then perpendicularly and
thwartway, so that it is somewhat difficult to conceive how they should
grow in that manner. By tearing off a small piece of it, and looking on the
ragged edge, I could among several of those fibres perceive small joints,
that is, one of those hairs split into two, each of the same bigness with the
other out of which they seem’d to grow, but having not lately had an
opportunity of examining their manner of growth, I cannot positively affirm
any thing of them.
But to proceed, The swelling of Sponges upon wetting, and the rising of
the Water in it above the surface of the Water that it touches, are both from
the same cause, of which an account is already given in the sixth
Observation.
The substance of them indeed, has so many excellent properties, scarce to
be met with in any other body in the world, that I have often wondered that
so little use is made of it, and those onely vile and sordid; certainly, if it
were well consider’d, it would afford much greater conveniencies.
That use which the Divers are said to make of it, seems, if true, very
strange, but having made trial of it my self, by dipping a small piece of it in
very good Sallet-oyl, and putting it in my mouth, and then keeping my
mouth and nose under water, I could not find any such thing; for I was as
soon out of breath as if I had had no Sponge, nor could I fetch my breath
without taking in water at my mouth; but I am very apt to think, that were
there a contrivance whereby the expir’d air might be forc’d to pass through
a wet or oyly Sponge before it were again inspir’d, it might much cleanse,
and strain away from the Air divers fuliginous and other noisome steams,
and the dipping of it in certain liquors might, perhaps, so renew that
property in the Air which it loses in the Lungs, by being breath’d, that one
square foot of Air might last a man for respiration much longer, perhaps,
then ten will now serve him of common Air.

Observ. XXIII. Of the curious texture of Sea-
weeds.
For curiosity and beauty, I have not among all the Plants or Vegetables I
have yet observ’d, seen any one comparable to this Sea-weed I have here
describ’d, of which I am able to say very little more then Schem. 9.
Fig. 2. what is represented by the second Figure of the ninth Scheme:
Namely, that it is a Plant which grows upon the Rocks under the water, and
increases and spreads it self into a great tuft, which is not onely handsomely
branch’d into several leaves, but the whole surface of the Plant is cover’d
over with a most curious kind of carv’d work, which consists of a texture
much resembling a Honey-comb; for the whole surface on both sides is
cover’d over with a multitude of very small holes, being no bigger then so
many holes made with the point of a small Pinn, and rang’d in the neatest
and most delicate order imaginable, they being plac’d in the manner of a
Quincunx, or very much like the rows of the eyes of a Fly, the rows or
orders being very regular, which way soever they are observ’d: what the
texture was, as it appear’d through a pretty bigg Magnifying Microscope, I
have here adjoin’d Schem. 14.
Fig. 1. in the first Figure of the 14. Scheme. which round Area ABCD
represents a part of the surface about one eighth part of an Inch in
Diameter: Those little holes, which to the eye look’d round, like so many
little spots, here appear’d very regularly shap’d holes, representing almost
the shape of the sole of a round toed shoe, the hinder part of which, is, as it
were, trod on or cover’d by the toe of that next below it; these holes seem’d
wall’d about with a very thin and transparent substance, looking of a pale
straw-colour; from the edge of which, against the middle of each hole, were
sprouted out four small transparent straw-colour’d Thorns, which seem’d to
protect and cover those cavities, from either side two; neer the root of this
Plant, were sprouted out several small branches of a kind of bastard
Coralline, curiously branch’d, though small.
And to confirm this, having lately the opportunity of viewing the large
Plant (if I may so call it) of a Sponge petrify’d, of which I made mention in

the last Observation, I found, that each of the Branches or Figures of it, did,
by the range of its pores, exhibit just such a texture, the rows of pores
crossing one another, much after the manner as the rows of eyes do which
are describ’d in the 26. Scheme: Coralline also, and several sorts of white
Coral, I have with a Microscope observ’d very curiously shap’d. And I
doubt not, but that he that shall observe these several kinds of Plants that
grow upon Rocks, which the Sea sometimes overflows, and those heaps of
others which are vomited out of it upon the shore, may find multitudes of
little Plants, and other bodies, which like this will afford very beautifull
objects for the Microscope; and this Specimen here is adjoin’d onely to
excite their curiosities who have opportunity of observing to examine and
collect what they find worthy their notice; for the Sea, among terrestrial
bodies, is also a prolifick mother, and affords as many Instances of
spontaneous generations as either the Air or Earth.