Inventors at Work_ with Chapters on Discovery George Iles 1648 downloads.pdf

The Project Gutenberg eBook of Inventors at Work, with
Chapters on Discovery

This eBook is for the use of anyone anywhere in the United States and
most other parts of the world at no cost and with almost no restrictions
whatsoever. You may copy it, give it away or re-use it under the terms
of the Project Gutenberg License included with this eBook or online at
www.gutenberg.org. If you are not located in the United States, you
will have to check the laws of the country where you are located
before using this eBook.

Title: Inventors at Work, with Chapters on Discovery

Author: George Iles

Release date: March 10, 2015 [eBook #48454]
Most recently updated: October 24, 2024

Language: English

Other information and formats: www.gutenberg.org/ebooks/48454

Credits: Produced by Chris Curnow, Harry Lamé and the Online
Distributed Proofreading Team at http://www.pgdp.net (This
file was produced from images generously made available
by The Internet Archive)

*** START OF THE PROJECT GUTENBERG EBOOK INVENTORS AT
WORK, WITH CHAPTERS ON DISCOVERY ***

Please see the Transcriber’s Notes at the
end of this text.

INVENTORS AT WORK

Copyright by Park & Co., Brantford, Ontario.
PROFESSOR ALEXANDER GRAHAM BELL.

Inventors at Work
With Chapters on Discovery

By George Iles
Author of “Flame, Electricity and the Camera”

Copiously Illustrated

New York
Doubleday, Page & Company
1907

Copyright, 1906, by
George Iles
Published October, 1906
All rights reserved, including that of translation into foreign languages, including the Scandinavian

TO MY FRIEND
JOSEPHUS NELSON LARNED
OF BUFFALO, NEW YORK

CONTENTS

PAGE

LIST OF ILLUSTRATIONS xiii

ACKNOWLEDGMENTS xxi

CHAPTER

I. INTRODUCTORY 1

II. FORM
Form as important as substance. Why a joist is stiffer than a plank.
The girder is developed from a joist. Railroad rails are girders of
great efficiency as designed and tested by Mr. P. H. Dudley 5

III. FORM CONTINUED. BRIDGES
Roofs and small bridges may be built much alike. The queen-post
truss, adapted for bridges in the sixteenth century, neglected for
two hundred years and more. A truss replaces the Victoria Tubular
Bridge. Cantilever spans at Niagara and Quebec. Suspension
bridges at New York. The bowstring design is an arch disguised.
Why bridges are built with a slight upward curve. How bridges are
fastened together in America and in England 18

IV. FORM CONTINUED. LIGHTNESS, EASE IN
MOTION
Why supports are made hollow. Advantages of the arch in
buildings, bridges and dams. Tubes in manifold new services.
Wheels more important than ever. Angles give way to curves 39

V. FORM CONTINUED. SHIPS
Ships have their resistances separately studied. This leads to
improvements of form either for speed or for carrying capacity.
Experiments with models in basins. The Viking ship, a thousand
years old, of admirable design. Clipper ships and modern
steamers. Judgment in design 52

VI. FORM CONTINUED. RESISTANCE
LESSENED
Shapes to lessen resistance to motion. Shot formed to move
swiftly through the air. Railroad trains and automobiles of
somewhat similar shape. Toothed wheels, conveyors, propellers
and turbines all so curved as to move with utmost freedom 65

VII. FORM CONTINUED. ECONOMY OF LIGHT
AND HEAT
Light economized by rightly-shaped glass. Heat saved by well-
designed conveyors and radiators. Why rough glass may be better
than smooth. Light is directed in useful paths by prisms. The
magic of total reflection is turned to account. Holophane Globes.
Prisms in binocular glasses. Lens grinding. Radiation of heat
promoted or prevented at will 72

VIII. FORM CONTINUED. TOOLS AND
IMPLEMENTS
Tools and implements shaped for efficiency. Edge tools old and
new. Cutting a ring is easier than cutting away a whole circle.
Lathes, planers, shapers, and milling machines far out-speed the
hand. Abrasive wheels and presses supersede old methods. Use
creates beauty. Convenience in use. Ingenuity spurred by poverty
in resources 89

IX. FORM CONTINUED. ABORIGINAL ART
Form in aboriginal art, as affected by materials. Old forms persist
in new materials. Nature’s gifts first used as given, then modified
and copied. Rigid materials mean stiff patterns. New materials
have not yet had their full effect on modern design 108

X. SIZE
Heavenly bodies large and small. The earth as sculptured a little at
a time. The farmer as a divider. Dust and its dangers. Models may
mislead. Big structures economical. Smallness of atoms.
Advantages thereof. Dust repelled by light 120

XI. PROPERTIES
Food nourishes. Weapons and tools are strong and lasting.
Clothing adorns and protects. Shelter must be durable. Properties
modified by art. High utility of the bamboo. Basketry finds much
to use. Aluminium, how produced and used. Qualities long
unwelcome or worthless are now gainful. Properties created at
need 135

XII. PROPERTIES CONTINUED
Producing more and better light from both gas and electricity. The
Drummond light. The Welsbach mantle. Many rivals of carbon
filaments and pencils. Flaming arcs. Tubes of mercury vapor 154

XIII. PROPERTIES CONTINUED
Steel: its new varieties are virtually new metals, strong, tough, and
heat resisting in degrees priceless to the arts. Minute admixtures in
other alloys are most potent 163

XIV. PROPERTIES CONTINUED
Glass of new and most useful qualities. Metals plastic under
pressure. Non-conductors of heat. Norwegian cooking box.
Aladdin oven. Matter seems to remember. Feeble influences
become strong in time 180

XV. PROPERTIES CONTINUED. RADIO-
ACTIVITY
Properties most evident are studied first. Then those hidden from
cursory view. Radio-activity revealed by the electrician. A
property which may be universal, and of the highest import. Its
study brings us near to ultimate explanations. Faraday’s prophetic
views 197

XVI. MEASUREMENT
Methods beginning in rule-of-thumb proceed to the utmost
refinement. Standards old and new. The foot and cubit. The metric
system. Refined measurement as a means of discovery. The
1
interferometer measures 5,000,000
inch. A light-wave as an
unvarying unit of length 208

XVII. MEASUREMENT CONTINUED
Weight, Time, Heat, Light, Electricity, measured with new
precision. Exact measurement means interchangeable designs, and
points the way to utmost economies. The Bureau of Standards at
Washington. Measurement in expert planning and reform 219

XVIII. NATURE AS TEACHER
Forces take paths of least resistance. Accessibility decides where
cities shall arise. Plants display engineering principles in structure.
Lessons from the human heart, eyes, bones, muscles, and nerves.
What nature has done, art may imitate,—in the separation of
oxygen from air, in flight, in producing light, in converting heat
into work: Lessons from lower animals. A hammer-using wasp 245

XIX. QUALIFICATIONS OF INVENTORS AND
DISCOVERERS
Knowledge as sought by disinterested inquirers. A plenteous
harvest with few reapers. Germany leads in original research. The
Carnegie Institution at Washington 267

XX. OBSERVATION
What to look for. The eye may not see what it does not expect to
see. Lenses reveal worlds great and small otherwise unseen.
Observers of the heavens and of seashore life. Collections aid
discovery. Happy accidents applied to profit. Popular beliefs may
be based on truth. An engineer taught by a bank swallow 279

XXI. EXPERIMENT
Newton, Watt, Ericsson, Rowland, as boys were constructive. The
passion for making new things. Aid from imagination and trained
dexterity. Edison tells how the phonograph was born. Telephonic
messages recorded. Handwriting transmitted by electricity. How
machines imitate hands. Originality in attack 299

XXII. AUTOMATICITY AND INITIATION
Self-acting devices abridge labor. Trigger effects in the laboratory,
the studio and the workshop. Automatic telephones. Equilibrium
of the atmosphere may be easily upset 329

XXIII. SIMPLIFICATION
Simplicity always desirable, except when it costs too dear. Taking
direct instead of roundabout paths. Omissions may be gainful.
Classification and signaling simpler than ever before 340

XXIV. THEORIES HOW REACHED AND USED
Educated guessing. Weaving power. Imagination indispensable.
The proving process. Theory gainfully directs both observation
and experiment. Tyndall’s views. Discursiveness of Thomas
Young 355

XXV. THEORIZING CONTINUED
Analogies have value. Many principles may be reversed with
profit. The contrary of an old method may be gainful. Judgment
gives place to measurement, and then passes to new fields 366

XXVI. NEWTON, FARADAY AND BELL AT WORK
Newton, the supreme generalizer. Faraday, the master of
experiment. Bell, the inventor of the telephone, transmits speech
by a beam of light 387

XXVII. BESSEMER, CREATOR OF CHEAP STEEL.
NOBEL, INVENTOR OF NEW EXPLOSIVES
Bessemer a man of golden ignorances. His boldness and
versatility. The story of his steel process told by himself. Nobel’s
heroic courage in failure and adversity. His triumph at last. Turns
an accidental hint to great profit. Inventors to-day organized for
attacks of new breadth and audacity 401

XXVIII. COMPRESSED AIR
An aid to the miner, quarryman and sculptor. An actuator for
pumps. Engraves glass and cleans castings. Dust and dirt removed
by air exhaustion. Westinghouse air-brakes and signals 417

XXIX. CONCRETE AND ITS REINFORCEMENT
Pouring and ramming are easier and cheaper than cutting and
carving. Concrete for dwellings ensures comfort and safety from
fire. Strengthened with steel it builds warehouses, factories and
bridges of new excellence 429

XXX. MOTIVE POWERS PRODUCED WITH NEW
ECONOMY
Improvements in steam practice. Mechanical draft. Automatic
stokers. Better boilers. Superheaters. Economical condensers.
Steam turbines on land and sea 446

XXXI. MOTIVE POWERS, CONTINUED. HEATING
SERVICES
Producer gas. Mond gas. Gas engines. Steam and gas engines
compared. Diesel engine best heat motor of all. Gasoline motors.
Alcohol engines. Steam and gas motors united. Heat and power
production together. District steam heating. Isolated plants.
Electric traction. Gas for a service of heat, light and power 457

XXXII. A FEW SOCIAL ASPECTS OF INVENTION
Why cities gain at the expense of the country. The factory system.
Small shops multiplied. Subdivided labor has passed due bounds
and is being modified. Tendencies against centralization and
monopoly. Dwellings united for new services. Self-contained
houses warmed from a center. The literature of invention and
discovery as purveyed in public libraries 478

INDEX 489

LIST OF ILLUSTRATIONS

Professor Alexander Graham Bell Frontispiece
Bell Homestead, Brantford, Ontario facing 2
Lens of ice focussing a sunbeam 5
Rubber strip suspended plank-wise and joist-wise 7
Board doubled breadthwise and edgewise 7
Telegraph poles under compression. Wires under tension 8
Rubber cylinder, flattened by compression, lengthened by
tension 9
Rubber joist compressed along top, extended along
bottom 10
Girder cut from joist 10
Rubber I-beam suspended flatwise and edgewise 10
Girder contours simple, built up, in locomotive draw-bars 11
Steel ore car 12
Bulb angle column, New York Subway 12
Strap rail and stringer, Mohawk & Hudson R. R., 1830 13
Plimmon H. Dudley facing 14
Dudley rails 16
Steel cross-ties and rails 17
King-post truss 18
Frames of four sides 19
Cross-section Arctic ship “Roosevelt” 20
Pair of compasses stretch a rubber strip 20
Queen-post truss 21
Upper part of roof truss, Interborough Power House, New
York 21
Two queen-post trusses from a bridge 22
Palladio trusses 22
Burr Bridge, Waterford, N. Y. 23
Howe and Pratt trusses 24

Baltimore truss 25
Whipple Bridge 25
Simple cantilevers 26
Victoria Bridge, Montreal, original form 27
Victoria Bridge, Montreal, present form 28
Cantilever Bridge, near Quebec 29
Kentucky River Cantilever Bridge 30
Arch Bridge, Niagara Falls 31
Bowstring Bridge, Philadelphia 32
Williamsburg Bridge, New York City 33
Continuous Girder Bridge, Lachine, near Montreal 34
Rubber strip supported at 4 points, and at 2 points 34
Plate girder bridge 35
Lattice girder bridge, showing rivets 36
Bookshelf laden and unladen, showing camber 36
Pin connecting parts of bridge 37
Bridge rollers in section and in plan 38
Girder sections in various forms 39
Rubber cylinders solid and hollow compared in sag 40
Handle bar of bicycle in steel tubing 40
A sulky in steel tubing 41
Pneumatic hammer in steel tubing 41
Fishing rod in steel tubing 41
Bridge of steel pipe 41
Arch bridge of steel pipe 42
Spiral fire-lighter 42
Spiral weld steel tube 42
Largest stone arch in the world, Plauen, Germany 43
Church of St. Remy, Rheims, France 43
Curve of suspended chain 44
Dam across Bear Valley, California 44
Ferguson locking-bar 45
Hand-hole plates, Erie City water-tube boiler 46
Bullock cart with solid wheels 47

Ball thrust collar bearings 48
Rigid bearings for axles of automobiles 48
Hyatt helical roller bearing. Ditto supporting an axle 49
Treads and risers of stairs joined by curves 49
Corner Madison Square Garden, New York 50
Two pipes with funnel-shaped junction 50
Model Basin, U. S. Navy, Washington, D. C. facing 54
Viking Ship 56
Clipper ship “Young America” 58
Steamship Kaiser Wilhelm II 60
Cargo steamer 61
U. S. Torpedo-boat destroyer 62
Cross-sections of ships 63
Racing automobile. Wedge front and spokeless wheels 66
Bilgram skew gearing 67
Grain elevator 68
Robins conveying belt 68
Ewart detachable link belting 69
Curves of turbines 70
Steel vanes of windmill 70
Pelton water wheel and jet 71
Luxfer prism 74
Fresnel lens 74
Lamp and reflector a unit 75
Inverted arc-light 75
Sacramento perch totally reflected in aquarium 77
Diagram illustrating total reflection 78
Holophane globe, sections 79
Holophane globe, diffusing curves 80
Holophane globe, three varieties 80
Holophane globe, and Welsbach mantle 81
Wire shortened while original direction is resumed 81
Four mirrors reflect a ray in a line parallel to first path 82
Prisms for Zeiss binocular glasses 82

Sections for Zeiss binocular glasses 83
Tools for producing optical surfaces 84
Bi-focal lens for spectacles 85
Canadian box-stove 86
Canadian dumb-stove 86
Tubing for radiator 87
Gold’s electric heater 87
Stolp wired tube for automobiles 87
Corrugated boiler 88
Pipe allowing contraction or expansion 88
Carving chisels and gouges 90
Lathe cutters 90
Ratchet bit brace 90
Eskimo skin scraper 91
Double tool drill cutting boiler plate 91
Common drill compared with ring drill 92
Twist drill 93
How a tool cuts metal 94
Dacotah fire-drill 94
Lathe, with parts in detail 95
Compound slide rest 96
Blanchard lathe 96
Turret lathe, with side and top views 97
Ericsson’s Monitor 98
Iron planer 99
Iron shaper 99
Milling machine 100
Milling cutters with inserted teeth 100
Milling cutters executing curves 101
Emery wheels 102
Carborundum wheel edges 102
Rolls to reduce steel in thickness 104
Gourd-shaded vessel, Arkansas 108
Gourd and derived pottery forms 109

Pomo basket 109
Bilhoola basket 110
Bilhoola basket, a square inch of 111
A free-hand scroll: same as woven 111
Yokut basket bowl 112
Sampler on cardboard 115
Bark vessel and derived form in clay 115
Vase from tumulus, St. George, Utah 116
Wooden tray. Clay derivative 116
Shell vessel. Earthen derivative 116
Electric lamps in candle shapes 117
Notre Dame de Bonsecours, Montreal 118
New Amsterdam Theater, New York facing 118
Cinders large and small on hearth 120
Cube subdivided into 8 cubes 121
Cube built of 27 cubes 122
Two rubber strips, varying as one and three in dimensions,
compared in sag 127
Air bubbles rising in oil 128
Dvorak sound-mill 132
Beam of light deflects dust 133
Dr. Carl Freiherr Auer von Welsbach facing 156
Boivin burner for alcohol 157
Alcohol lamp with ventilating hood 158
Welsbach mantle 159
Tantalum lamp 160
Tungsten lamp of Dr Kuzel 160
Hewitt mercury-vapor lamp 161
Sections Pearlite and Steel facing 164
Cleaning Cars by the “Vacuum” Method facing 164
Open hearth furnace 165
Professor Ernst Abbe facing 182
Bliss forming die 184
Bliss process of shell making 184

Mandolin pressed in aluminium 185
Pressed seamless pitcher 185
Barrel of pressed steel 185
Range front of pressed steel 186
Pressed paint tube and cover 186
Norwegian cooker 189
Aladdin oven 190
Mayer’s floating magnets 193
Alum crystal, broken and restored 194
Marble before and after deformation by pressure 195
Professor Ernest Rutherford facing 202
Professor A. A. Michelson facing 214
Michelson interferometer 215
Light-wave distorted by heated air 216
Ancient Egyptian balance 219
Rueprecht balance 220
Earnshaw compensated balance wheel 223
Riefler clock 224
Photometer 227
Compass needle deflected by electric wire 230
Compass needle deflected by electric coil 231
Maxwell galvanometer 231
Weston voltmeter 232
Micrometer caliper measuring 1⁄1000 inch 236
Plug and ring for standard measurements 237
Two lenses as pressed together by Newton 237
Newton’s rings 238
Flat jig or guide 239
Deciduous cypress 247
Deciduous cypress, hypothetical diagram 248
Section of pipe or moor grass; of bulrush 251
Human hip joint 252
Valves of veins 252
Built-up gun 253

Achromatic prisms and lens 255
Three levers 256
Arm holding ball 256
Beaver teeth 258
Narwhal with twisted tusk 259
Lower part of warrior ants’ nest, showing dome 260
Wasp using pebble as hammer 260
Cuban firefly 263
Dr. R. S. Woodward facing 276
Perforated sails for ships 292
Edison phonograph 312
Telegraphone 314 and
facing 314
Gray Telautograph 315 and
facing 318
Hussey’s mower or reaper 321
Mergenthaler linotype, justifying wedges 323
Schuckers’ double-wedge justifier 324
Two wedges partly in contact, and fully in contact 325
Polarized light shows strains in glass 327
Stop-motion 330
Dexter feeding mechanism 331
Schumann’s “Traumerei” in musical score and on Pianola
roll 334
Mechanism of Pianola 335
Automatic Telephone 336 and
facing 336
Blenkinsop’s locomotive, 1811 345
Notes on loose cards in alphabetical order 350
Sectional bookcase, desk and drawers 351
Burke telegraphic code 353
Burke simplified telegraphic signals 354
Pupin long-distance telephony 367
Water-gauge direct and reversed 370

Thomas Alva Edison facing 374
Cube-root extractor 376
Square-root extractor 377
Sturtevant ventilating and heating apparatus 380
Bicycle suspended from axle 382
Telephones receiving sound through a beam of light 395
Selenium cylinder with reflector 398
Perforated disc yielding sound from light 399
Sir Henry Bessemer facing 402
First Bessemer converter and ladle 406
New Ingersoll coal cutter 418
Drill steels 418
Sculptor at work with Pneumatic Chisel facing 418
Haeseler air-hammer 419
Rock drill used as hammer 420
Little Giant wood-boring machine 420
Water lifted by compressed air 421
Harris system of pumping by compressed air 422
Hardie nozzle for painting by compressed air 423
Vacuum renovators for carpets and upholstery 424
Injector sand-blast, Drucklieb’s 425
Vertical receiver, inter- and outer-cooler 426
Concrete silo foundation 431
Concrete silo 432
Mansion in Concrete, Fort Thomas, Kentucky facing 432
Wall of two-piece concrete blocks 434
Ransome bar for concrete 436
Corrugated steel bar 436
Thacher bar 436
Kahn bar 437
Hennebique armored concrete girder 437
Monier netting 437
Expanded metal diamond lath 438
Tree box in expanded steel 438

Royal Bank of Canada, Havana facing 438
Lock-woven wire fabric 439
Column forms for concrete, Ingalls Building, Cincinnati 440
Section of chimney, Los Angeles, Cal. 441
Coignet netting and hook 442
Section of conduit, Newark, N. J. 442
Water culvert 443
River des Pêres Bridge, Forest Park, St. Louis 444
Memorial Bridge, Washington, D. C. 444
Francis vertical turbine wheel 446
5000 Horse-Power Allis-Chalmers Steam Engine facing 448
Smoke-jack 449
Power House, Interborough Co., New York, exterior facing 450
Schmidt superheater 451
Power House, Interborough Co., New York, interior facing 452
De Laval steam turbine, sections 453
Westinghouse-Parsons Steam Turbine facing 454
Combustible gas from a candle 458
Taylor gas-producer 460
Four-cycle gas engine 463
Fire syringe 467
Sturtevant fan wheel, without casing 472
Sturtevant Monogram exhauster and solid base heater 473
New York Central R. R. Electric Locomotive with
Five-Car Train facing 476

ACKNOWLEDGMENTS

Aid in writing this volume is acknowledged in the course of its chapters.
The author’s grateful thanks are rendered also to Dr. L. A. Fischer, of the
Bureau of Standards at Washington, who has revised the paragraphs
describing the work of the Bureau; to Mr. C. R. Mann of the Ryerson
Physical Laboratory, University of Chicago, who corrected the paragraphs
on the interferometer; to Mr. Walter A. Mitchell, formerly of Columbia
University, New York, who revised most of the chapters on measurement.
Mr. Thomas E. Fant, Head of the Department of Construction and Repair at
the Navy Yard, Washington, D. C., gave the picture of the model basin here
reproduced. Mr. Walter Hough of the National Museum, Washington, D. C.,
contributed a photograph of the Pomo basket also reproduced here. Mr.
John Van Vleck and Mr. Henry G. Stott of New York, Mr. George R.
Prowse and Mr. Edson L. Pease of Montreal, have furnished drawings and
photographs for illustrations of unusual interest. Mr. George F. C. Smillie,
of the Bureau of Engraving, Washington, D. C., Mr. Percival E. Fansler, Mr.
Ernest Ingersoll, and Mr. Ashley P. Peck, of New York, have read in proof
parts of the chapters which follow. Their corrections and suggestions have
been indispensable.
Professor Bradley Stoughton, of the School of Mines, Columbia University,
New York, has been good enough to contribute a brief list of books on steel,
supplementing the chapter on that theme written with his revision. Had it
been feasible, other chapters would have been supplemented in like manner
by other teachers of mark. In 1902 the American Library Association
published an annotated guide to the literature of American history, engaging
forty critics and scholars of distinction, with Mr. J. N. Larned as editor. It is
hoped that at no distant day guides on the same helpful plan will be issued
in the field of science, duly supplemented and revised from time to time.

In the present volume the author has endeavored to include in his survey the
main facts to the close of May, 1906.
New York, September, 1906.

INVENTORS AT WORK

CHAPTER I
INTRODUCTORY

nventors and discoverers are justly among the most honored of men. It is
I they who add to knowledge, who bring matter under subjection both in
form and substance, who teach us how to perform an old task, as
lighting, with new economy, or hand us gifts wholly new, as the
spectroscope and the wireless telegraph. It is they who tell us how to shape
an oar into a rudder, and direct a task with our brains instead of tugging at it
with our muscles. They enable us to replace loss with gain, waste with
thrift, weariness with comfort, hazard with safety. And, chief service of all,
they bring us to understand more and more of that involved drama of which
this planet is by turns the stage and the spectator’s gallery. The main
difference between humanity to-day and its lowly ancestry of the tree-top
and the cave has been worked out by the inventors and discoverers who
have steadily lifted the plane of life, made it broader and better with every
passing year.
On a theme so vast as the labors of these men a threshold book can offer but
a few glances at principles of moment, to which the reader may add as he
pleases from observations and experiments of his own. At the outset Form
will engage our regard: first, as bestowed so as to be retained by girders,
trusses and bridges; next, as embodied in structures which minimize
friction, such as well designed ships; or as conducing to the efficiency of
tools and machines; or deciding how best heat may be radiated or light
diffused. A word will follow as to modes of conferring form, the influence
on form of the materials employed, and the undue vitality of old forms that
should long ago have bidden us good-by. Structures alike in shape may
differ in size. Bigness has its economies, and so has smallness. Both will
have brief attention, with a rapid survey of new materials which enable a
builder to rear towers or engines bolder in dimensions than were hitherto
possible.
Substance, as important as form, will next receive a glance. First a word
will be said about the properties of food, raiment, shelter, weapons and

tools. Then, the properties of fuels and light-givers will be considered, as
steadily improved in their effectiveness. How properties are modified by
heat and electricity will be remarked, with illustrations from steels of new
and astonishing qualities, and from notable varieties of glass produced at
Jena. A few pages will recount some of the striking phenomena of radio-
activity displayed by radium, thorium and kindred substances, phenomena
which are remolding the fundamental conceptions of physics and chemistry.
A survey of form and properties, however cursory, must involve
measurement, otherwise an inventor cannot with accuracy embody a plan in
a working machine, or know exactly how strong, elastic, or conducting a
rod, a wire, or a frame is. Measuring instruments will be sketched, their use
delineated, and the results of precise measurement noted as an aid to the
construction of modern mechanism, the interchangeability of its parts, the
economy of materials and of energy in every branch of industry. Next will
follow a chapter noting tasks which Nature has long accomplished, and
which Art has still to perform, as in converting at ordinary temperatures
within the human body fuel energy into work. Plainly, a broad field opens
to future invention as it copies the function of plants and animals; functions
to be first carefully observed, then explained and at last imitated with the
least possible waste of effort.
The equipment and the talents for invention and discovery are now touched
upon. First, knowledge, especially as the fruit of disinterested inquiry;
Observation, as exercised by trained intelligence calling to its aid the best
modern instruments; Experiment, as an educated passion for building on
original lines. Then, in the mechanical field, we bestow a few glances at
self-acting machines, at the simplicity of design which makes for economy
not only in building, but in operation and maintenance. Either in designing
a new machine, or in reaching a great truth, such as Universal
Development, there is scope for Imagination upon which we next pause for
a moment. A succeeding chapter outlines how theories may be launched and
tested, how analogy may yield a golden hint, the profit in rules that work
both ways, or even in doing just the opposite of what has been done without
question for ages past.

Copyright, 1906, by Park & Co., Brantford, Ontario, Canada
BELL HOMESTEAD, BRANTFORD, ONTARIO, CANADA.
Alexander Graham Bell and his Daughter in the Foreground.
Here the Telephone was Perfected in 1874.
Now the Home of the Bell Telephone Memorial Association.

From this brief consideration of method we now pass to a few men who
have exemplified method on the loftiest plane; we come into the presence
of Newton, the supreme generalizer, and observe his patience and
conscientiousness, as remarkable as his resourcefulness in experiment, in
mathematical analysis. Even greater in experiment, while lacking
mathematical power, is Faraday, who next enlists our regard. This great
man, more than any other investigator, laid the foundations of modern
electrical science and art. Moreover he distinctly saw how matter might
reveal itself in the ‘radiant’ condition now engaging the study of the
foremost inquirers in physics.
Electricity has no instrument more useful in daily life, or in pure research,
than the telephone. Now follows a narration by its creator, Professor Bell, of
his photophone which transmits speech by a beam of light. This recital
shows us how an inventor of the first rank proceeds from one attempt to

another, until his toil is crowned with success. Next we hear the story of the
Bessemer process from the lips of Sir Henry Bessemer himself, affording us
an insight into the methods and characteristics of a mind ingenious,
versatile and bold in the highest degree. An inventor of quite other type is
next introduced,—Nobel, who gave dynamite to the quarryman and miner,
smokeless powder to the gunner and sportsman. His unfaltering heart, beset
as he was by constant peril, marks him a hero as brave as ever fought
hazardous and dreary campaigns to a victorious close.
Many advances in mechanical and structural art have been won rather
through a succession of attacks by one leader after another, than by a single
decisive blow from a Watt or an Edison. A great band of inventors,
improvers, adapters, have accomplished notable tasks with no record of
such a feat as Bessemer with his converter, or Abbe with Jena glass. A brief
chapter deals with some of the principal uses of compressed air, an agent of
steadily increasing range. As useful, in a totally different sphere—that of
building material—is concrete, especially as reinforced with steel. A sketch
of its applications is offered. Then follows the theme of using fuels with
economy, of obtaining from them motive powers with the least possible
loss. This field is to-day attracting inventors of eminent ability, with the
prospect that soon motive powers will be much cheapened, with incidental
abridgment of drudgery, a new expansion of cities into the country, and the
production of light at perhaps as little as one-third its present cost. A page or
two are next given to a few social aspects of invention, its new aid and
comfort to craftsmen, farmers, householders comparatively poor. It will
appear that forces working against the undue centralization of industry
grow stronger every day.
A closing word gives the reader, especially the young reader, a hint or two
in case he wishes to pursue paths of study the first steps of which are taken
in this book.
In 1900 was published the author’s “Flame, Electricity and the Camera,” in
which are treated some of the principal applications of heat, electricity and
photography as exemplified at the time of writing. That volume may
supplement the book now in the reader’s hands.

CHAPTER II
FORM

Form as important as substance . . . Why a joist is stiffer than a plank . . . The girder is developed
from a joist . . . Railroad rails are girders of great efficiency as designed and tested by Mr. P. H.
Dudley.

A lens of ice focussing a sunbeam.

ne January morning in Canada I saw a striking experiment. The sun
O was shining from an unclouded sky, while in the shade a Fahrenheit
thermometer stood at about twenty degrees below zero. A skilful
friend of mine had moulded a cake of ice into a lens as large as a reading
glass; tightly fastened in a wooden hoop it focussed in the open air a
sunbeam so as to set fire to a sheet of paper, and char on a cedar shingle a
series of zigzag lines. There, indeed, was proof of the importance of form.
To have kept our hands in contact with the ice would have frozen them in a
few minutes, but by virtue of its curved surfaces the ice so concentrated the
solar beam as readily to kindle flame. Clearly enough, however important
properties may be, not less so are the forms into which matter may be
fashioned and disposed. Let us consider a few leading principles by which
designers have created forms that have economized their material, time and
labor, and made their work both secure and lasting. We will begin with a

glance at the rearing of shelter, an art which commenced with the putting
together of boughs and loose stones, and to-day requires the utmost skill
both of architects and engineers.
Building in its modern development owes as much to
Strength and
improvement in form as to the use of stronger materials, Rigidity.
brick instead of clay, iron and steel instead of wood. A
stick as cut from a tree makes a capital tent-pole, and will serve just as well
to sustain the roof of a cabin. For structures so low and light it is not worth
while to change the shape of a stick. By way of contrast let us glance at an
office building of twenty-five stories, or the main piers of the new Quebec
Bridge rising 330 feet above their copings. To compass such heights stout
steel is necessary, and it must be disposed in shapes more efficient than that
of a cylinder, as we shall presently see.
In most cases strength depends upon form, in some cases strength has
nothing whatever to do with form; if we cut an iron bar in two its cross-
section of say one square inch may be round, oblong, or of other contour,
while the effort required to work the dividing shears will in any case be the
same. But shearing stresses, such as those here in play, are not so common
or important as the tension which tugs the wires of Brooklyn Bridge, or the
compression which comes upon a pillar beneath the dome of the national
capitol. When we place a lintel over a door or a window, we are concerned
that it shall not sag and let down the wall above it in ruin: we ensure safety
from disaster by giving the lintel a suitable shape. When we build a bridge
we wish its roadway to remain as level as possible while a load passes, so
that no hills and hollows may waste tractive power: levelness is secured by
a design which is rigid as well as strong. If a railroad has weak, yielding
rails, a great deal of energy is uselessly exerted in bending the metal as the
wheels pass by. A stiff rail, giving way but little, avoids this waste. To
create forms which in use will firmly keep their shape is accordingly one of
the chief tasks of the engineer and the architect.

Rubber strip suspended plank-wise, and joist-wise.

Board doubled breadthwise through small semi-circle AB,
then edgewise through large semi-circle CD.

Forms of this kind, well exemplified in the steel columns
Plank and Joist.
and girders of to-day, have been arrived at by pursuing a
path opened long ago by some shrewd observer. This man
noticed that a plank laid flatwise bent much beneath a load, but that when
the plank rested on its narrow edge, joist fashion, it curved much less, or
hardly at all. Thus simply by changing the position of his plank he in effect
altered its form with reference to the strain to be borne, securing a decided
gain in rigidity. Let us repeat his experiment, using material much more

yielding than wood. We take a piece of rubber eight inches long, one inch
wide and one quarter of an inch thick. Placing it flatwise on supports close
to its ends we find that its own weight causes a decided sag. We next place
it edgewise, taking care to keep it perpendicular throughout its length, when
it sags very little. Why? Because now the rubber has to bend through an arc
four times greater in radius than in the first experiment. Suppose we had a
large board yielding enough to be bent double, we can see that there would
be much more work in doubling it edgewise than flatwise. The rule for
joists is that breadth for breadth their stiffness varies as the square of their
depth, because the circle through which the bending takes place varies in
area as the square of its radius. In our experiment with the rubber strip by
increasing depth four-fold, we accordingly increased stiffness sixteen-fold;
but the breadth of our rubber when laid as a joist is only one-fourth of its
breadth taken flatwise, so we must divide four into sixteen and find that our
net gain in stiffness is in this case four-fold.

Telegraph poles under compression. Wires under tension.

Here let us for a moment dwell upon the two opposite ways in Girders.
which strength may be brought into play, as either compression

or tension is resisted. An example presenting both is a telegraph pole, with
well-balanced burdens of wires. Its own weight and its load of wires,
compress it, as we can prove by measuring the pole as stretched upon the
ground before being set in place, and then after it is erected and duly laden.
Should this downward thrust be excessive, the pole would be crushed and
broken down. The strung wires are not in compression, but in the contrary
case of tension, and are therefore somewhat lengthened as they pass from
one pole to the next. Now observe a mass first subjected to compression,
and next to tension. In bearing a pound weight a rubber cylinder is
compressed and protrudes; when the weight is suspended from this
cylinder, the rubber is lengthened by tension. In each case the effect is
vastly greater than with wood or steel, because rubber has so much less
stiffness than they have.

Rubber Flattened by Lengthened
cylinder. compression. by tension.

Both tension and compression are exhibited in our little rubber joist, which
illustrates the familiar wooden support beneath the floors of our houses.
This form in giving rise to the girder has been changed for the better. Let us
see how. As the rubber joist sags between its ends, we observe that its upper
half is compressed, and its lower half extended, the two effects though

small being quite measurable. As we approach the central line, A B, this
compression and tension gradually fall to zero; it is clear that only the
uppermost and undermost layers fully call forth the strength of the material,
the inner layers doing so little that they may be removed with hardly any
loss. Hence if we take a common joist and cut away all but an upper and
lower flange, leaving just web enough between to hold them firmly
together, we will have the I-beam which among rectangular supports is
strongest and stiffest, weight for weight. In producing it the engineer has
bared within the joist the skeleton which confers rigidity, stripping off all
useless and burdensome clothing. An I-beam made of rubber when laid
flatwise over supports at its ends will sag much; when laid edgewise it will
sag but little, clearly showing how due form and disposal confer stiffness on
a structure.

Rubber joist in section, compressed along the top, extended along the bottom.

Girder cut from joist.

Rubber I-beam suspended flatwise, and edgewise.

Simple girder contours.

Girder contours simple and built up.

Girder forms in locomotive draw-bars.

Girders of steel are rolled and riveted together at the mills in a variety of
contours, each best for a specific duty, as the skeleton of a floor, a column,
or a part of a bridge. Their lengths, if desired, may far exceed those possible
to wood. Their principal simple forms are the I-beam; T, the tee; L, the
angle; C, the channel; and the Z-bar. Of these the I-beam is oftenest used;
its two parallel flanges are at the distance apart which practice approves,
they are united by a web just stout enough not to be twisted or bent in
sustaining its burdens. Crank shafts of engines, to withstand severe strains,
are built in girder fashion; so are the side-bars of locomotives and the
braces of steel cars. Plates riveted together may serve as compound girders
or columns of great strength and rigidity. In the New York subway the
riveted steel columns which support the roof have a contour which enlarges
at the extremities.

100,000 pound steel ore car built by the Standard Steel Car Co., Pittsburg, for the
Duluth, Missabe & Northern R. R. Of structural steel throughout. Weight
unloaded, 32,200 pounds.

Section of standard bulb angle column, New York Subway.

By all odds the most important girder is the rail in railroad
The Rail.
service. Let us glance at phases of its development in America,
as illustrating the importance of a right form to efficient service.
At the outset of its operations, in 1830, the Mohawk & Hudson Railroad,
now part of the New York Central & Hudson River Railroad, employed a
rail which was a mere strap of iron two and one half inches wide, nine
sixteenths of an inch thick, with upper corners rounded to a breadth of one

and seven eighths inches; it was laid upon a pine stringer, or light joist, six
inches square, and weighed about 14 pounds per yard. Thin as this rail was,
its proportions were adequate to bearing a wheel-flange which protruded
but half an inch or even less. Where the builders of that day sought rigidity
and permanence was in the foundations laid beneath their stringers. Except
upon embankments there were for each track two pits each two feet square,
three feet from centre to centre, filled with broken stone upon which were
placed stone blocks each of two cubic feet. On the heavy embankments
cross-ties were laid; these were found to combine flexibility of
superstructure with elasticity of roadbed, so that they were adopted
throughout the remainder of the track construction and continue to this hour
to be a standard feature of railroad building.

Cross Section Top View
Strap rail and stringer, Mohawk & Hudson R. R., 1830.

It was soon observed that the surface of a track as it left the track-maker’s
hands, underwent a depression more or less marked when a train passed
over it. With a strap-iron rail this depression was so great that engines were
limited to a weight of from three to six tons. Before long the strap form was
succeeded by a rail somewhat resembling in section the rail of to-day. Year
by year the details of rolling rails were improved, so that sections weighing
thirty-five to forty pounds to the yard came into service. These at length
united a hard bearing surface for the wheel-treads, a guide for the wheel-
flanges, and a girder to carry the wheel-loads and distribute them to the
cross-ties. Thereupon the weights of engines and cars were increased,

leading, in turn, to a constant demand for heavier rails. In 1865 a bearing
surface was reached adequate for wheel-loads of 10,000 to 12,000 pounds,
the rail weighing fifty-six to sixty pounds to the yard. But the metal was
still only iron, and wore rapidly under its augmented burdens. Then was
introduced the epoch-making Bessemer process and steel was rolled into
rails four and one-half inches high, of fifty-six to sixty-five pounds to the
yard, of ten to fifteen-fold the durability of iron. In design the early steel
rails were limber so that they rapidly cut the cross-ties under their seats,
pushing away the ballast beneath them. Because they lacked height they
had but little stiffness, one result being that the spikes under the rails were
constantly loosened, exaggerating the deflection due to passing trains.
Throughout the lines every joint became low, and the rails took on
permanent irregularities under the pounding of traffic, dealing harmful
shocks to the rolling stock.
This was the state of affairs in 1880, when Mr. Plimmon Dudley’s Track
H. Dudley invented his track-indicator. This apparatus, Indicator.
placed in a moving car, records by ever-flowing pens on
paper every irregularity, however slight, in the track over which it passes.
When railroad engineers first saw its records, they believed that the thing to
do was to restore their roads to straightness by the labor of track-men. It
was abundantly proved that the real remedy lay in using a rail of increased
stiffness, that is, a rail higher and heavier. Mr. Dudley, in the light of
records covering thousands of miles of running, added fifteen pounds to a
rail which had weighed sixty-five pounds, and gave it a height of five
inches instead of four and one half, while he broadened its upper surface. At
a bound these changes increased the stiffness of the section sixty per cent.,
the gain being chiefly due to added height. Proof of this came when his
improved rail was found to be much stiffer than that of the Metropolitan
Railway, of London, which weighed eighty-four pounds to the yard and had
a base of six and three eighths inches, but a height of only four and one half
inches. In July, 1884, the Dudley rail was laid in the Fourth Avenue viaduct,
New York; so satisfactory did it prove that in less than two years five-inch
rails were in service on three trunk lines. Then followed their introduction
throughout America, their smoothness and stability as a track giving them
acceptance far and wide.

Photograph by F. M. Somers, Cincinnati, O.
PLIMMON H. DUDLEY
of New York.

The performance of the Dudley rail so impressed Mr. William Buchanan,
Superintendent of Motive Power for the New York Central Railroad that in
1889 he planned his famous passenger engine, No. 870, which entered upon
active duty in April, 1890. It carried 40,000 pounds upon each of its two
pairs of driving wheels, instead of 31,250, as did its heaviest predecessor;
its truck bore a burden of 40,000 pounds more; its loaded tender weighed

80,000 pounds, making a total of 100 tons, an advance of forty per cent.
beyond the weight of the heaviest preceding engine and tender. Mr.
Buchanan’s forward stride has been worthily followed up. Since 1890,
passenger locomotives have nearly doubled in the weight borne upon their
axles, while tractive power has increased in the same degree. Through
express and mail trains have more than doubled in weight, and their speeds
have increased thirty to forty per cent. The tonnage of an average freight
train has been augmented four to six-fold, with reduction of the crews
necessary to keep a given amount of tonnage in motion. This economy is
reflected in a reduction of rates which are now in America the lowest in the
world, and which steadily fall. In capacity for business united with stability
of roadbed, mainly due to stronger and stiffer rails and to adapted
improvement in rolling stock, railroad progress in the past fifteen years is
equal to that of the sixty years preceding. With rails increased to a weight of
100 pounds to the yard there is shown, even in passing over the joints, an
astonishing degree of smoothness as contrasted with the jolting action of
rails comparatively low and light. Stiffness of rail reduces the destructive
action of service, originally enormous, upon both equipment and track,
lowering in a marked degree the cost of maintenance. Size of rail as well as
form plays a part in this economy. A passenger train weighing 378 tons has
required 820 horse power on 65-pound rails, and but 720 horse power on
80-pound rails, the speed in both cases being 55 miles an hour; it is
estimated that with 105-pound rails 620 horse power would have sufficed.
In freight service Dudley rails have reduced the resistances per ton from
between 7 and 8 pounds to one half as much; a further reduction, to 3
pounds, is in prospect. In passenger service, with rails of unimproved type
the resistance at 52 miles an hour is 12 pounds per ton; with Dudley rails
this resistance for heavy trains is not augmented when the speed rises to 65
or 70 miles an hour. Dudley rails, and rails derived from their designs, are
now in use on three fourths of all the trackage of American railroads,
effecting a vast economy. Seventy-five years ago the DeWitt Clinton
locomotive and tender weighed only five sixths as much as the main pair of
driving wheels, boxes, axle, and connecting rods of the present Atlantic
type of engine. That such an engine can haul a heavy train at seventy miles
an hour largely depends upon the production of that simple and important
element in railroading, its rail.[1]

[1] Mr. Dudley’s rails, and those of other designers, are fully illustrated and discussed in
“Railway Track and Track Work,” by E. E. Russell Tratman. Second edition. New York,
Engineering News Publishing Co.

Dudley rails.

Steel cross-ties and rails.—Carnegie Steel Co., Pittsburg.

In Ninth Street, Pittsburg, the rails of the traction line are for some distance
carried on steel ties similar in form, as here shown.

CHAPTER III
FORM—Continued. BRIDGES

Roofs and small bridges may be built much alike . . . The queen-post truss, adapted for bridges in the
sixteenth century, was neglected for two hundred years and more . . . A truss bridge replaces the
Victoria Tubular Bridge . . . Cantilever spans at Niagara and Quebec . . . Suspension bridges at New
York . . . The bowstring design is an arch disguised . . . Why bridges are built with a slight upward
curve . . . How bridges are fastened together in America and England.

King-post truss. AK, king-post.

ails are girders used by themselves: girders are Roofs and Bridges
R often combined in trusses; of these much the largest
and most important are employed for bridges.
Much Alike.

There is now under construction near Quebec a cantilever bridge whose
channel span of 1,800 feet will be the longest in the world. See page 29. It
will take us a little while to understand how so bold a flight as this was ever
dared. We will begin with a glance at a truss of the simplest sort, such as we
may find beneath the roof of an old-fashioned barn. A pair of rafters, AB
and AC, are inclined to each other at an obtuse angle, and are fastened to
the horizontal beam, BC, at B and C. Their apex, A, is joined to BC by the
king-post, AK, which binds the three strongly and firmly. This whole

structure makes up a triangle, and so does each of its halves, ABK and
AKC. No other shape built of straight pieces will keep its form under strain.
Take in proof say four pieces of lath and unite them with a freely turning
pin at each corner to make the frame, ABCD; it is easily distorted by a
slight pull or push; but insert cross-pieces, AC and BD so as to divide the
square into triangles, and at once the frame resists any strain not severe
enough to break the wood or crush its fastenings. As the roof presses down
the frame ABC, its sides, AB and AC, tend to slide away at their lower ends,
B and C, but this is prevented by the horizontal beam, BC, which while it
holds them in place is itself so stretched as to be held level and straight.
This calling into play of tension constitutes the chief merit of the truss, and
enables it in roofs and bridges to span breadths impossible to simple beams
bending downward under compressive strains. Not only in houses, but in
ships, the truss has great value; it was introduced in this field by Robert
Seppings of Chatham, in England, about 1810. To resist the pressure of
grinding ice, the “Roosevelt” is built with trusses of great strength. She
sailed in 1905, under Commander Peary, for a voyage of Arctic discovery.

Frames of four sides. For rigidity
diagonals are needed, AC, BD.

Were our barn roof flat instead of sloping to form a truss, its supporting
timbers, under compression, would have a decided sag from which BC is
free. When we fashion a small model of a king-post truss, its sides, AB and
AC, must be of metal or wood because they will be in compression; the
king-post, AK, and the base, BC, which will be under tension, may be of
rubber or cord. Always as in this case the parts of a truss exposed to
compression must be of rigid material. When a part may be of cord, rope or
wire, we know that it is resisting tension.[2]
[2] A model easily put together illustrates the truss in its simplest form. Take a pair of
wooden compasses, each half of which is 15 inches long, such as are sold for blackboard
use by the Milton Bradley Co., Springfield, Mass., at 50 cents. At each tip fasten, by the
ring provided with the compasses, a chair castor such as may be had at any hardware store.

Join the tips of the castors by a rubber strip. Holding the compasses upright, and applying
pressure from the hand, they will extend until the rubber will be so stretched as to become
almost perfectly horizontal. Various weights may in succession be suspended from the
compass-joint, replacing manual pressure, and serving to measure the exerted tensions.

Cross-section of the “Roosevelt,” Commodore Peary’s new Arctic ship. Reproduced by permission
from the Scientific American, New York.

Pair of compasses stretch a rubber strip.

Wrought iron exerts about as much resistance to compression as to tension;
so does steel. For this reason, and on account of their great strength, they
have immense value in building. Cast iron can bear only about one sixth as
much tension as compression, so that it is useful as foundations, for the bed-

plates of engines and machinery and the like, but is unsuitable for girders.
Wood is much stronger under tension than compression; in white pine this
proportion is as eight to one. In designing timber bridges the strains are,
therefore, as far as possible, arranged for tension.

Queen-post truss.
DE, HO, queen-posts.

Upper part of a roof truss.
Interborough Power House, New York.

Let us now enter another barn, about one half wider than the first, and look
upward at its rafters. We see its roof sustained by timbers disposed as
DCMH, to avoid the undue weight necessary for a design resembling that of

our first roof, ABC. Instead of one upright post, AK, as in that case, we
have now two, DE and HO, called queen-posts, sustaining the horizontal
beam, CM. In large modern roofs the simple queen-post is modified and
multiplied, as in the main power house of the Interborough Rapid Transit
Company, West 59th St., New York. Returning to our simple queen-post
design, let us imagine a creek flowing between walls spanned by DCMH;
that truss and a mate to it, parallel at a distance of say ten feet, would easily
carry a roadway and give us a bridge. A truss for a bridge must be much
stronger than for a roof of equal span, because a bridge has to bear moving
loads which may come upon it suddenly, giving rise not only to serious
strains but to severe vibrations, all varying from moment to moment.

Two queen-post trusses form a bridge.

Palladio trusses.

The queen-post truss was remarkably developed by Palladio’s Long
Palladio, a famous Italian architect of the sixteenth Neglected Truss.
century. Two of his designs, here given in outline, are
from his work on architecture published in 1570; their contours, little
changed, are in vogue to-day. Strangely enough the trusses of Palladio, for
all their merit, passed out of notice until their principles were revived and
improved by Theodore Burr, in 1804, in a wooden bridge over the Hudson
at Waterford, New York. This bridge had spans respectively of 154, 160 and
180 feet, stretches impossible to single wooden beams. Professor J. B.
Johnson, an eminent engineer, says that this is the most scientific design
ever invented for an all-wooden bridge; during fifty years it stood unrivaled
as a model for highway purposes in this country. The Burr bridges were
usually covered in, so as to resemble the roofs we began by inspecting. In a
truss bridge each part bounded by two adjacent uprights, as DOEH in the
queen-post figure on page 21, is a panel; every part under compression, as
DO, HE, is a strut, post, or column; every part subject to tension as DE,
HO, is a tie.

Burr Bridge, Waterford, N. Y.
DO, HE, struts. DE, HO, ties. DHEO, panel.

In 1830 as the first American railroad train sped on its way, a new era
dawned for the bridge builder as well as for his neighbors. At once sprang
up a demand for bridges longer and stronger than those which in the past
had served well enough. A score of wagons laden with wheat or potatoes
were a good deal lighter than a locomotive followed by a train of loaded
freight cars. A market-wagon, too, could easily be taken aboard a ferry-boat,
but for an engine and its cars a bridge was imperative, if the stream were

not so wide as to forbid all opportunity to the bridge builder. His response
to the demands of the railroad was two-fold. First in the use of metal instead
of wood, beginning with iron rods to bind together frames of timber. As iron
became cheaper and its value more and more evident, he employed it for
additional parts of his structure until at last he built the whole bridge of
iron.
To-day good steel is so cheap that railroad bridges are seldom reared of
anything else. Besides using stronger materials, the designer has gradually
improved the form of his structure, not only in its parts but as a whole, so
that to-day, strength for strength, a bridge may be only one tenth as heavy
as a bridge of fifty years ago. Advances in form have been due to
experience as one type has been compared with another; meanwhile the
mathematicians have carried their analysis of strains as far as the extreme
complexity of their problems will allow, greatly to the betterment of
designs.
In building a bridge, as in rearing many other structures, girders of various
contours are used. In bridge building the I-beam is most employed. When
the roadway proceeds on the top chord, as DH, in the queen-post figure,
page 21, we have a deck bridge; when it is built on the bottom chord, as
CM, we have a through bridge.

HOWE TRUSS

PRATT TRUSS

The Burr bridge of 1804, already mentioned, included an The Burr Bridge
arch and was in part sustained by struts projecting from Simplified by
abutments. These features were omitted by William Howe and Pratt.
Howe in the bridge which he patented in 1840, and
which was, as far as is known, the first successor to a design of Palladio in
employing a simple truss for long spans. The Howe truss was built of wood,
except its terminal tie-rods, which were of iron; it has been repeated
thousands of times throughout the world. In 1844 Thomas W. and Caleb
Pratt patented a bridge which in design was the converse of Howe’s. Its
diagonals of iron were used in tension, while its vertical struts of timber
were in compression; in the Howe pattern the diagonals were in
compression, the verticals in tension. This plan, by shortening the struts,
diminished the cross-section necessary in a truss. When wrought iron took
the place of wood for bridges, the Pratt design became the most popular of
all, combining as it did more desirable features than any of its rivals. To-day
for long spans the Baltimore truss is much in favor. Its stresses, that is, its
resistances to change of form under strain, are readily ascertained; the
shortness of its panels means strength; and its diagonals have the inclination
which wide and varied experience has shown most desirable. The roadway,
it will be observed, is upheld by sub-verticals, that is, by verticals which
reach the floor from half the height of a panel.

Diagram of Baltimore truss.

Whipple Bridge.

An important study concerns itself with the intensity and distribution of
strains, first in girders, next in trusses, and lastly, in bridges as units, all
with intent to ensure the best possible designs throughout. In this field of
inquiry the pioneer was Squire Whipple, a maker of mathematical
instruments in Utica, N. Y., who published in 1847 his analysis of the
strains in a truss bridge due to its own weight and to its moving loads. With
the laws of these strains in mind he devised several bridges of great merit,
the most noteworthy being reared in 1852 on the Rensselaer & Saratoga
Railroad, seven miles north of Troy, which did service until 1883; its sides
or web system had ties extended across two panels in double intersection.
In a long truss bridge, which in its entirety may be regarded as a girder of
the utmost size, the cross pieces between the main beams of the structure
are much less heavy than if continuous plates, of no more strength. The
original form of the Victoria Bridge at Montreal was that of a continuous
tube of iron, square in section; it has given place to a truss bridge of five
times greater capacity which weighs only twice as much. (Illustrations of
both on pages 27 and 28.)
Thus to lessen weight in comparison with strength is a matter of great
importance in a suspended structure, which must not only bear its own
weight, but carry heavy moving loads.

Simple cantilevers.
FG, HI, are first separate; then in contact; last are joined by a plank laid above
them.

VICTORIA BRIDGE, MONTREAL.
Original tubular form designed by Robert Stephenson.

VICTORIA BRIDGE, MONTREAL,
Rebuilt with trusses.

CANTILEVER BRIDGE ACROSS THE ST. LAWRENCE, NEAR QUEBEC.
Total length, CF, 3300 feet. Channel span, DE, 1800 feet. Central truss, AB, 675 feet.

In most cases a bridge crosses a valley or a river in a Advantages of the
place which permits the engineer to erect scaffolding to Cantilever, Arch,
support his trusses until they can be united and become and Bowstring
Designs.
self-sustaining. In some places this course is denied; a
river such as the Ohio or the Mississippi may have to be
spanned at a point where the waters in a single day may rise forty feet,
bearing along trees and timbers with destructive violence. As a rule the
difficulty is met by employing cantilever spans which require no
scaffolding for their construction. To understand their principle let us
suppose that on opposite banks of a creek we roll out to meet each other the
joists FG and HI, taking care that the parts over the water shall always be
lighter than the parts on land. When the joists at last touch they are secured
to each other as a continuous roadway. Or, while they are at a moderate
distance apart they may be joined by a third timber laid across the gap from
one to the other. In practice the simple principle thus illustrated is
developed and varied in many ways, but in every application the one rule is
that the trusses as they stretch out from the two sides of a pier shall balance
each other, the shore ends being duly weighted down or safely anchored to
solid rock. And thus, at length, we come to the wonderful bridge, six miles
west of Quebec, whose channel span of 1,800 feet will be the longest ever
reared. See illustration, page 29. From the cantilever arms, DA and BE, will
be suspended the central truss, AB, of 675 feet. A cantilever span may be
much longer than a simple truss because on a pier, as D of this bridge, a
part, DA, of the whole span, DE, is balanced either, as in this case, by a
shore span, CD, or by a corresponding part of the next span should that
span not extend to the shore but pass from one pier to another.

Kentucky river cantilever bridge

The first cantilever bridge in America was designed by C. Shaler Smith for
the Cincinnati Southern Railroad, to cross the Kentucky River; it was built
in 1876-7.

Arch bridge, Niagara Falls

Spanning the gorge of Niagara, close to the Falls, is an arch bridge of 840
feet in its central span, which, in its construction during 1898, followed the
plan originated by James B. Eads in building the St. Louis bridge nearly
thirty years before. As scaffolding was out of the question in both cases,
each bridge was built out from its piers on the cantilever principle. An arch
is sometimes disguised as a modified bowstring, as in the Burr design of
1804, a horizontal tie connecting the extremities of the arched rib and
taking its thrust, dispensing with the abutments demanded by an arch. In the
chords of such a pattern the strength comes as near to uniformity
throughout as practical considerations permit, avoiding the losses of early
days when one part of a bridge might be twice as strong as another. The
bowstring was adopted for the great span of 5421⁄2 feet over the Ohio at
Cincinnati built in 1888, and for the span of 5461⁄2 feet erected at Louisville
in 1893. A bowstring 533 feet long, forming part of the Delaware river
bridge of the Pennsylvania Railroad, built in 1896, in Philadelphia, is
outlined on page 32. At Bonn, on the Rhine, there was completed in 1904 a
bridge whose central span is a bowstring 6161⁄4 feet long.

Bowstring Bridge, Pennsylvania R. R., Philadelphia.

If we take the design of an arch bridge and turn it upside
Suspension
down we have a contour such as that of the Williamsburg Bridges and
Suspension Bridge, opened in 1903 between Brooklyn Continuous
Girders.
and Manhattan, depicted on page 33. For the utmost
length this is the only available span; it brings into play
the tensile strength of wire, the strongest form that steel can take. A steel
cable of suitable diameter, if it had to support only itself, might safely be
three miles long. A suspension bridge has another advantage in employing
an anchorage to bear strains which would break down a simple truss resting

on piers. As first erected suspension bridges were liable to extreme and
harmful vibration, in many cases being shaken to pieces by storms of no
great violence. It was found that this vibration was checked and that safety
was ensured by introducing stiffening trusses which, at the same time,
benefited the bridge by distributing the load uniformly throughout the
sustaining cables.

WILLIAMSBURG BRIDGE, NEW YORK CITY.

At Lachine, about eight miles west of Montreal, on the line of the Canadian
Pacific Railroad, a remarkable bridge crosses the St. Lawrence river. Its
design is that of a continuous girder of four spans, the two side spans being
269 feet each in length, and the two others each 408 feet. This type is
discussed by Mr. Mansfield Merriman and Mr. Henry S. Jacoby in Part IV,
page 30, of their work on Roofs and Bridges. One of the advantages
presented is that deflection under live load is less, and stiffness greater than
for simple, discontinuous girders, the harmful effect of oscillation being
thus diminished. Furthermore, less material is required than for simple,
discontinuous spans. Both these elements of gain are brought out in placing
a strip of rubber, AD, upon four equidistant points of support, when we find
that BC, the central third of the strip sags less than either AB or CD, the
first or last third. Cutting off one-third of the whole strip we deprive the
removed piece, at its surface of separation, of the cohesion which did much

to keep the whole strip, before cutting, almost horizontal at that point. We
take AB, our short removed piece of rubber, and lay it at its ends on two
points of support; it now serves in a rough-and-ready way as a model of a
simple truss, all by itself; its decided sag shows it much less rigid than when
it formed a part of an unbroken and longer structure. Continuous girders
despite their advantages are seldom employed; they are liable to serious
difficulties; among these may be mentioned that changes, often
unavoidable, of level in piers and abutments cause them to suffer great
reversals of stress, always a source of danger; furthermore, variations of
length due to changes of temperature are, of course, much greater and more
troublesome to provide against than in the case of discontinuous girders.

Continuous girder bridge, Canadian Pacific R. R., Lachine, near Montreal.

Rubber strip supported at 4 points, and at 2 points.

Plate girder bridge.

Whether spans are long or short, engineers are fairly well
Best Proportions
agreed as to the best proportions for girders and panels. for Spans: A
They consider that a girder should have about one- Slight Upward
twelfth to one-tenth as much depth as span; and that the Curve is Gainful.
Pins or Rivets in
weight of a web should be about equal to that of its Fastening.
flanges. They usually give panels twice as much depth as
length, with a tendency to increase the proportion of depth to length, in
order to minimize the deflections and oscillations which shorten the life of a
structure. For definite lengths of span, particular types of construction are
preferred; usually for lengths of from 20 to 125 feet, plate girders are
chosen; for spans of 125 to 150 feet riveted lattice trusses are built; for
spans of 150 to 600 feet pin-connected trusses are employed. Here we reach
the economical limit of a length for simple trusses; beyond 600 feet the
engineer is obliged to have recourse either to a cantilever or a suspension
bridge.

Part of lattice girder bridge, showing rivets.

Whatever the breadth of the stream or the chasm over which he is to build a
roadway, each case must be studied in the light of its special circumstances.
There must be due regard to business as well as to engineering
considerations; the designer will bear in mind that types of parts
customarily turned out at great steel works are procurable in less time, and
at less cost, than novel types requiring to be manufactured to order. Then, in
speed of construction, he will remember that a pin-connected bridge can be
built much faster than a riveted structure. Furthermore, every part must be
vastly stronger than ordinary duty requires. Tempests and floods may
suddenly arise; at any instant a derailment or a collision may create a strain
of the utmost severity; and even under ordinary circumstances it must not
be forgotten that train loads grow constantly heavier because economy lies
that way.

Upper shelf, unladen, has upward curve or camber.
Lower similar shelf is straightened by its load.

One detail of bridge design is worth a moment’s attention. When a book-
shelf is a thin board, quite straight as manufactured, it sags in the middle
when fully burdened. This downward dip may be avoided by making the
shelf at first with a slight curve which brings the middle a little higher than
the ends. In bridge building a like curve, or camber, is given to each span so
that when fully loaded it will be level or nearly so. In a span of 500 feet it is
found that a rise of half a foot at the centre is sufficient. In suspension
bridges, for the sake of strengthening the structure, the camber far exceeds
this ratio.

Pin connecting parts of a bridge.

In fastening together the parts of a bridge the usual American practice,
already mentioned, is to employ pins which pass through eye bars. In
England riveting is preferred, as shown in the figure of the lattice truss,
page 36. This difference in methods arose through the use of materials
which differed. In the construction of bridges the English engineer started
with the flanged girder of cast or rolled iron, or some other form of stiff
beam, and as bridges increased in size so as to require the framing of a
truss, his whole effort was directed toward making that truss as much like
the original flanged or box girder as possible. The American engineer, on
the other hand, had at first little or no iron or steel to work with, and of
necessity used wood. As the necessary bridges were of considerable span,
the only feasible method was to pin together small pieces of wood so as to
form a connected series of triangles. To make rigid joints in wood was
impracticable, and indeed rigid joints were not desired, because the strength
of wood is slight when strains are applied in any direction other than that of
the fibres of the piece, and the pin joint insures just this line of action. As a
rule a riveted bridge requires more metal than a pin-connected design, takes
more time to build, but demands somewhat less skill. To provide for
changes in length as a bridge is subjected to variations of temperature,
friction rollers are used to support its extremities. In the first suspension

bridge at Niagara Falls, built by Roebling, a little cement accidentally
covered the friction rollers and prevented them from turning; fortunately the
structure escaped the destruction to which it was thus exposed.

Bridge rollers in section and plan.
New York, Pennsylvania & Ohio R. R.

We have now taken a rapid survey of some of the methods by which the
designer of bridges plans a structure which is at once safe and to the utmost
extent economical of material. Step by step he has discovered how little
steel he may use for designs all the bolder because his hand is so sparing of
weight. His success began in adopting the girder, which we have seen to be
in effect the working skeleton long concealed within the common joist; the
cantilever span near Quebec, which compasses 1,800 feet in its flight, has
been dissected out of preceding burden bearers in the same way. Its metal
stands forth as so much sheer muscle kept to the most telling lines,
unencumbered by a single pound of idle substance. A designer of such a
fabric is an artist skilled in disengaging from masses of material every
ounce that can be wisely removed. In some cases, as when Roebling linked

together New York and Brooklyn, a bridge is created as much a thing of
beauty as of use, as graceful as it is strong.[3]
[3] Mr. David A. Molitor has a chapter, copiously illustrated, on the esthetic design of
bridges, beginning page 11 in the “Theory and Practice of Modern Framed Structures,” by
Mr. J. B. Johnson and other authors, New York, John Wiley & Sons. Eighth edition, revised
and enlarged. $10.00.

CHAPTER IV
FORM—Continued. WEIGHT AND FRICTION DIMINISHED.

Why supports are made hollow . . . Advantages of the arch in buildings, bridges and dams . . . Tubes
in manifold new services . . . Wheels more important than ever . . . Angles give way to curves.

aving glanced at methods by which forms, judiciously chosen,
H economize the materials of buildings and rails, of bridges diverse in
type, we pass to further consideration of these and like shapes, to find
that they effect a saving in material while they make feasible a new
boldness of plan, and introduce new elements of beauty. We will also
remark that judicious forms prevent waste of energy as structures are either
set in motion, or serve to convey moving bodies. Incidentally we shall see
that well chosen shapes insure a structure against undue hurt and harm.

Square Octagonal 16-Sided Round
Girder sections.

In lofty structures, the box girder is frequently employed Hollow Columns
as a column or a beam because it has even greater and Tubes.
rigidity than the I-beam; usually it has four sides, but it
may have eight, sixteen, or more, and thus step by step we come to a hollow
cylindrical column which has, indeed, the best form that can be bestowed
on supporting material. Chinese builders learned its economy on the distant
day when they adopted the bamboo for their walls and roofs. Comparison
with a solid stick of timber of like weight and substance will show that an
equal length of bamboo is decidedly preferable. The inner half of a round
solid stick does comparatively little in holding up a burden; to remove that
half is therefore as gainful as to strip from a joist the timber surrounding its

working skeleton. At first the journals or axles of engines and large
machines, as well as the axles of railroad cars and the shafts of steamships
were solid; to-day, in a proportion which steadily increases, they are hollow.
The advantage of this form comes out when we take two cylinders of
rubber, alike in length and weight, one solid, the other hollow. Supporting
both at their ends, the hollow form sags less than the solid form, proving
itself to be the more rigid of the two.

Solid rubber cylinder sags much.
Hollow rubber cylinder sags less.

Handle-bar of bicycle in steel-tubing.

A sulky in steel tubing.

A pneumatic hammer, steel tubing.

Fishing-rod in steel tubing.

Bridge of steel pipe.

With like advantage seamless tubing is adopted for a broad variety of
purposes. It builds bicycles and sulkies which far out-speed vehicles of
solid frames; it is worked up into elevator cages, mangle rolls, pneumatic
tools, fishing-rods, magazine-rifle tubes, inking rollers, farm machinery,
poles, masts and much else where strength and lightness are to be united.
Steel tubing is readily bent into any needed contour, even when of
considerable diameter. Mr. Egbert P. Watson has pointed out its availability
for highway bridges of about forty feet span, no professional bridge-
builders being needed for their construction. Near Saxonville,
Massachusetts, a pipe-arch bridge, eighty feet long, provides a roadway
across the Sudbury River, while carrying within its pipe a stream which
forms part of the Boston water system. A bridge of similar form, 200 feet
long, spans Rock Creek in the City of Washington. The Eads bridge
crossing the Mississippi, at St. Louis, employs for each span eight steel
tubes of nine inches exterior diameter. Tubes large and small have been
strengthened by adopting the model of an old-fashioned fire-lighter, or spill,
a bit of paper rolled spirally as a hollow tube. Blow sharply into it and you
but tighten its joints. In like manner tubes and pipes of metal are all the
tighter when their seams are spiral instead of longitudinal. An eager quest
for combined strength and lightness in the bicycle has ended in the choice
of tubes spirally welded.

Arch bridge of steel pipe,
Sudbury River, near Saxondale, Mass.

Spiral fire-lighter.

Spiral weld steel tube.

When builders of old began to rear masonry they repeated in
Arches.
stone or brick the forms they had constructed in wood.
Accordingly the lintels of their doors and windows were flat. It
was a remarkable step in advance when the arch was invented, probably by
a bricklayer, spanning widths impossible to horizontal structures. A flat
course of stone or brick presses downward only; an arch presses sidewise as
well as downward. It is this sidewise thrust, calling into play a new
resource, that gives the arch its structural advantage. In modern masonry the
boldest arch is that of the bridge at Plauen, Germany, with its span of 2951⁄4
feet. Of pointed arches the chief sustain the walls of Gothic cathedrals; it
was to counteract the outward thrust of these arches that external buttresses
were reared, either solid, as at St. Remy in Rheims, or flying, as at Notre
Dame in Paris. The Saracenic arch, offering more than half of a circle, is not
so strong as the Roman arch, but it has a grace of its own, fully revealed in
the Alhambra, and in the incomparable mosque at Cordova. A chain of
small links, a watch-chain, for example, freely hanging between two points
of support strikes out a catenary curve; this Galileo suggested as the outline
for an arch in equilibrium; it is adopted for suspension bridges.

Longest stone arch in the world, Plauen, Germany.

Church of St. Remy, Rheims, France.
Section across buttressed choir.

Curve of suspended chain.

Dam across Bear Valley, San Bernardino County, California.

“The arch,” says Mr. William P. P. Longfellow in “The Column and the
Arch,” “was the great constructive factor in the architecture of the Roman
Empire; it added enormously to the builder’s resources in planning, and to
his means of architectural effect. It gave him the means of spanning wide
openings, and when expanded into the vault, of covering great spaces; it
habituated him to curved lines and surfaces. Helped by it, and spurred by
the new wants of the complex Roman civilization, he enlarged the scale of
his buildings and greatly increased the intricacy of their plans. He used his
new combinations with a boldness and fertility of invention that have been

the wonder of the world from that age to ours, constructing on a scale that
dwarfed everything that had gone before except the colossal buildings of
Egypt. Under a new stimulus, and with new means of effect, Roman
building greatly outstripped that of the Greeks in extent, in variety, and
magnificence.”
An arch built on its side, with its convexity upstream, and its ends braced
against rocky banks, serves admirably as a dam. It has in many cases
withstood floods much higher than those expected by its designers. Such
dams must not be too long, or what is saved in thickness is more than lost in
length. Arches inverted are used in many places as gulleys for drainage.
Near Bristol, in England, they anchor the cables of the Clifton Suspension
Bridge, at a depth of eighty-two feet below the surface of the ground. Many
tunnels finished in masonry have outlines which are two arches united, the
lower arch being inverted. The Cloaca Maxima, the famous sewer at Rome,
is of this pattern; it is twenty-six feet high, sixteen feet broad, and is now in
its twenty-fifth century of service.

Ferguson locking-bar pipe. East Jersey Pipe Co,.
Paterson, N. J.

From arches, built of parts of circles, let us pass to the
Circles and Other
circle itself, and glance at the use of tubes of circular Curves.
section as we begin to consider how resistances to
motion may be minimized. The use of the bamboo not only for building, but

for the carriage of water, began in the remote past. As structural material it
was light and strong as we have noticed; laid upon the ground it was a
ready-made water pipe of excellent form. When trees were hollowed out to
convey water, when clay was modeled into tubes, the hollow cylindrical
shape of the bamboo was in the mind of the Asiatic artisan, to be faithfully
copied. That form has descended to all modern piping for water, steam, and
gas, because the best that a pipe can take. No other shape has,
proportionately to capacity, so little surface for friction inside or rust
outside. A locking-bar water pipe, devised by Mephan Ferguson, of Perth,
Australia, is made of two plates of equal width, curved into semi-circles
which are pressed at their ends into channel bars of soft steel. As the
locking-bars and joints are opposite each other, their joints can be tightly
closed by a simple machine which exerts pressure in a straight line. This
construction may be used not only for pipes, but for hydraulic cylinders, air
receivers, mud and steam drums, tubular boilers and boiler shells where
high pressures are to be withstood.
A steam boiler or other vessel under severe internal strains had best be
spherical if equality to resistance is particularly desired. Usually a
cylindrical shape is much more convenient, and no other is given to simple
steam boilers or to the tubes of water-tube or fire-tube boilers. Tubes
comparatively narrow, are readily manufactured without seam, so that they
may be quite safe though thin; large boilers of plates riveted together, must
be built of thick metal. It was estimated by Mr. F. Reuleaux, the eminent
engineer, that if such boilers could be made in one continuous piece of
metal by the Mannesmann process, so successful in tube-making, an
economy in weight of at least one third would be feasible.

Hand-hole plates.
Erie City water-tube boiler.

In water-tube boilers a gainful departure from the circular form in a detail
of their design is worthy of notice. In order that their tubes may be kept
sound and clean they are rendered accessible by hand-holes which pierce
the front and back of the boiler. Usually these hand-holes and their covers
are round, a form which makes it necessary to put the cover outside the
boiler where even a good joint, well stayed, may leak or give way under a
pressure which tends to force apart the cover and its seat. In the Erie City
boiler the covers are elliptical; they are readily passed through the hand-
holes so as to rest not on the outside, but on the inside, of the boiler, where
the steam pressure makes their joints all the tighter. A further advantage is
that each elliptical plate is large enough to give access to two tubes instead
of one, lessening the lines of juncture along which leakage may occur.
It was a memorable day when first a round log or stick was thrust Wheels.
under a burden, easing its motion and leading to the wheel by

piecemeal improvements. A section cut off from the end of a round log is
to-day the wheel for ox-carts in China and India. In its crudest form a roller
enables a man to drag a load instead of carrying it, and he can readily drag
much more than he can carry. Wheelwrights of old soon found that a wheel
need not be solid, that strong spokes, a sound rim, and a metal tire embody
the utmost strength and lightness. Roller and ball bearings much extend the
benefits of simple wheels; they lessen friction in the best typewriters,
bicycles, and elevators; in wagons, carriages, and automobiles roller
bearings are so helpful that their use should be universal. Of notable
efficiency is the Hyatt bearing, formed by winding a steel strip into a spiral
roller. This device has a flexibility which enables it to conform to
irregularities of motion much better than can a solid cylinder.

Bullock cart with solid wheels.

For machinery the wheel is indispensable. The hand does its work chiefly in
moving to and fro, as in sawing and whittling. Machines outdo manual toil
by moving swiftly and continuously in a circle: instead of the smoothing
iron we have the mangle, boards are planed by rotary knives, timber is
divided by circular saws, and the steam turbine is displacing the steam
engine which every moment has to check the momentum of huge
reciprocating masses. Noteworthy in this regard is the perfecting press
which prints a newspaper from a continuous roll, as contrasted with the old
machine which demanded for each impression a distinct series of to and fro

movements. The Harris Rotary Press for job printing is of like model. It
feeds itself with 6,500 sheets an hour, printing from a stereotype or an
electrotype curved upon its cylinder. The lathe, simple enough a century
ago, has been developed into machines of great complexity, power, and
variety, all with the original rotary mandrel as their essential feature.
Milling machines, steadily gaining more and more importance, employ
rotary cutters which dispense with the manual chipping and filing of former
days.

Section—A B
Ball thrust collar bearing.
Ball Bearing Co., Philadelphia.

Rigid bearings for driving axles of automobiles.
Ball Bearing Co., Philadelphia.

Hyatt helical roller bearing.

Hyatt rollers supporting an axle.

Treads and risers joined by curves.

Wood as commonly hewn, sawn, and planed; bricks as
Angles Replaced
usually molded; stone as it leaves an ordinary hammer, by Curves.
all have flat sides and square edges. Hence it has been
easiest to build walls and floors which meet at right angles, and to leave
sharp corners on outer walls, windows, doorways, and chimneys. This is
being changed for the better; in staircases the boards on which we tread and
those which join them together now meet in smooth curves; so do the walls
of rooms as they reach ceilings and floors, conducing to ease and
thoroughness in sweeping and cleansing. In outer walls, in doorways and
windows, similar curves reduce liability to hurt and harm. A wagon wheel
easily knocks pieces from an angle of brickwork; it makes little impression
on bricks retiring from the street line in a sweeping curve, as in the Madison
Square Garden, New York. Factory chimneys have long been built round
instead of square; to-day in the best designs the ducts to a chimney are also
freely curved. In blast furnaces this is the rule for every part of the
structure, ensuring gain in strength, lessening resistance to the flow of
gases, and thus saving much fuel. When waterpipes varying in diameter are
joined, the junction should be a gradual curve, otherwise retarding eddies
will arise, wasting a good deal of energy; the same precaution is advisable
in laying pipes for steam or gas. The elbows of pipes for gas, steam or water
exert the least possible friction when given the utmost feasible radius. All
the various parts of heavy guns are curved, since any sharpness of angle at a

joint brings in a hazard of rupture under the tremendous strains of
explosion.

Corner Madison Square Garden,
Madison Avenue and 26th Street,
New York.

Two pipes with funnel-shaped junction.

Embossing and stamping machines may either decorate a sheet of note
paper or make a tub from a plate of steel. Whatever their size these
machines have the edges of their dies nicely rounded, so as to avoid tearing
the material they fashion. To ensure the utmost strength in the machines
themselves they are contoured in ample curves. In hydraulic presses,

subjected to strains vastly greater, the same shaping is imperative, otherwise
a cylinder may part abruptly with disastrous effect. So, too, in the
manufacture of magnets and electro-magnets, their terminals are well
rounded to ensure the closest possible approach to uniformity of field and
of working effect.
A glance at a warship discovers her varied use of curves in defence; to
deflect assailing shot and shell, her plates are given bulging lines, her
turrets are built in spherical contours, and her casemates are convex
throughout. On much the same principle fortifications are rendered bomb-
proof, or rather bomb-shedding; while outworks are so inclined that bombs
fall to distances at which they do little or no harm. As in war so in peace;
there is gain in building breakwaters with an easy curve; to give their
masonry and timbers a perpendicular face would be to invite damage,
whereas a flowing contour like that of a shelving beach, slows down an
advancing breaker and checks its shock. In rearing lighthouses to bear the
brunt of ocean storms the outline of a breakwater is repeated to the utmost
degree feasible. Often, however, the base supporting a lighthouse is too
small in area for such an outline to be possible.

CHAPTER V
FORM—Continued. SHIPS

Ships have their resistances separately studied . . . This leads to improvements of form either for
speed or for carrying capacity . . . Experiments with models in basins . . . The Viking ship, a thousand
years old, of admirable design . . . Clipper ships and modern steamers. Judgment in design.

n giving form to a ship a designer has a three-fold Forms of Ships
I aim,—strength, carrying capacity and speed. Strength
is a matter of interior build as much as of external
Adapted to
Special
Resistances.
walls; it is conferred by girders, stays and stiffeners
which we have already considered, so that we may here
pass to the general form of the hull, which decides how much freight a ship
may carry, and, to a certain extent, how fast she may run. A ship is the
supreme example of form adapted to minimize resistance to motion; its
lesson in that regard will be the chief theme of this chapter. Until the close
of the eighteenth century the resistance to the progress of a ship was
regarded as a single, uncompounded element, plainly enough varying with
the vessel’s speed and size. It was Marc Beaufoy, who first in 1793 in
London, pointed out that a ship’s resistance has two distinct components;
first, friction of the shell or skin with the water through which the vessel
moves, dependent upon the area of that skin; second, resistance due to the
formation of waves as the ship advances, dependent upon the speed of the
vessel and the shape of her hull. Other resistances have since been detected,
but these two are much the most important of all; each varies independently
of the other as one ship differs from another in form, or as in the same ship
one speed is compared with another. To take a simple case: a ship’s model
of a certain form, of perfectly clean skin, is towed at various speeds and the
pull of the tow-line is noted; then the same model with its skin roughened
and covered with marine growths is towed at the same speeds, and much
greater pulls are observed in the tow-line. The wetted surface is the same in
the two series of experiments, the speeds correspond throughout, and the
increase of resistance due to a roughening of surface can only mean that the
friction between the water and the submerged skin has increased. Next we
take a model of certain form and definite size, and a second model having

the same area of wetted surface but a different form; we tow both models at
the same speed to find that one requires a decidedly stronger pull than the
other. This difference cannot be due to frictional resistance of surface, for
this is the same in both models, therefore it must be due to the increased
resistance offered by the water as it is pushed aside, a resistance measurable
in the created waves. Mr. Edmund Froude, an eminent English authority,
says:
“For a ship A, of the ocean mail steamer type, 300 feet long and 311⁄2 feet
beam and 2,634 tons displacement, going at 13 knots an hour, the skin
resistance is 5.8 tons, and the wave resistance 3.2 tons, making a total of 9
tons. At 14 knots the skin resistance is but little increased, namely 6.6 tons;
while the wave resistance is nearly double, namely, 6.15 tons. Mark how
great, relatively to the skin resistance, is the wave resistance at the moderate
speed of 14 knots for a ship of this size and of 2,634 tons weight or
displacement. In the case of another ship B, 300 feet long, 46.3 feet beam,
and 3,626 tons displacement—a broader and larger ship with no parallel
middle body, but with fine lines swelling out gradually—the wave
resistance is much more favorable.[4] At 13 knots the skin resistance is
rather more than in the case of the other ship, being 6.95 tons as against 5.8
tons; while the wave resistance is only 2.45 tons as against 3.2 tons. At 14
knots there is a very remarkable result in this broader ship with its fine
lines, all entrance and run and no parallel middle body:—at 14 knots the
skin resistance is 8 tons as against 6.6 tons in ship A, while the wave
resistance is only 3.15 tons as compared with 6.15 tons. The two resistances
added together are for B only 11.15 tons, while for A, a smaller ship, they
amount to 12.75 tons.”
[4] The entrance is that part of the ship forward where it enters the water and swells out to
the full breadth of the ship; the run is the after part from where the ship begins to narrow
and extending to the stern. A ship may consist of only entrance and run; it may have a
middle body of parallel sides between the entrance and run. Such a middle body is
discussed by Lord Kelvin in “Popular Lectures and Addresses,” Vol. III, Navigation, p.
492.

These figures show that a designer must bear in mind the Experimental
speed at which this ship is to run; they prove that he may Basins.
choose one form to minimize friction, or another form if
he particularly wishes to bring wave-making resistance to the lowest
possible point. Forms of these two kinds are readily studied when

represented in models 12 to 20 feet in length towed through tanks built for
the purpose. Experiments of this kind were undertaken as long ago as 1770,
in the Paris Military School; the methods then inaugurated and copied in
London at the Greenland Docks were greatly improved by Mr. William
Froude in a tank which he constructed at Torquay in England, in 1870. His
modes of investigation, duly adopted by the British Admiralty, and after his
death continued by his son, Mr. Edmund Froude, have created a new era in
ship design. To-day in Europe and America there are eleven such tanks as
Mr. Froude’s, all larger than his and more elaborate in their appliances. In
addition to learning the behavior of models diverse in type, Mr. Froude
worked out the rules which subsist between the performance of a model and
that of a ship of like form; these he brought to proof in 1871 when he towed
Her Majesty’s Ship Greyhound, and verified his estimates in towing its
model. The rules concerned, known as those of mechanical similitude, are
given in detail by Professor Cecil H. Peabody in his “Naval Architecture,”
page 410. While experiments become more and more valuable as one
refinement succeeds another, there is always much well worth knowing to
be learned from the actual behavior of a vessel as she takes her way through
a canal, a shallow river, or the storm-beaten stretches of the sea.
The experimental tank of the United States Navy at Washington, is 470 feet
long, 44 broad, and 141⁄2 deep; it is arranged for models 20 feet in length.
See the page opposite. The towing carriage is a bridge spanning the tank
just above the water; it is a riveted steel girder. The towing mechanism, of
massive proportions, is driven by four electric motors of abundant power. A
double set of brakes brings the carriage gradually and quietly to rest from a
high speed. A self-acting recorder measures both speed and resistance. Ship
builders may have models built by the Bureau in charge, that of
Construction and Repair of the United States Navy Department, and have
these models towed at any desired speeds, paying simple cost.

MODEL BASIN, U. S. NAVY YARD, WASHINGTON, D. C.

It was in 1880 that the lessons of towing experiments with models began to
be adopted in practice. As a result the forms of steamers have been greatly
improved. Originally their lines were taken from those of sailing vessels
but, as dimensions grew bolder and speeds were increased, it became clear
that steamers demanded wholly different lines of their own. These lines,
fortunately, may be plainly disclosed in experiments with a model, because
a steamer usually runs on an even keel, in which position a model is easily
driven through a tank. A sailing vessel, on the contrary, is nearly always
heeled over by the wind so that it seldom runs on an even keel; tank
experiments, therefore, avail but little for the improvement of its lines. Even
were the model inclined at various angles in one test after another, sails
must be omitted, with their influence on steering, their lifting and burying
effects, often extreme.

1. Starboard Side. 2. Horizontal Sections. 3. Vertical Sections. 4. Central Longitudinal Section. 5.
Part of the Gunwhale inside, with its Skirting in Front and in Section. 6. Section through AB. 7.
Bird’s Eye View.
THE VIKING SHIP.
Enlarged illustration (155 kB)

A thousand years ago the Vikings of Norway roved the
A Viking Ship a
seas in boats of a form which is admired to-day. To those Thousand Years
hardy adventurers swiftness and seaworthiness meant Old.
nothing less than life and victory, their eyes perforce
were keen to note what craft sped fastest through the water, what new
curves kept waves from coming aboard. Perchance as they refined upon
keel and rib they took golden hints from the shapes of gulls and fish. To be
sure, long before science was dreamt of, they had to work by rule-of-thumb,
but the thumb was joined to brains that did honor to human nature. On page
56 is illustrated the Viking Ship unearthed early in 1880 at Godstad, near
Sandefjord in Norway, in a mound where, according to tradition, a king and
his treasure had been buried. It is the most complete and the best preserved
vessel of ancient date in existence. It is fully described and pictured in “The
Viking Ship,” by Mr. N. Nicolaysen, a work published in 1882 by Mr.

Albert Cammermeyer, Christiania. Mr. Nicolaysen regards the vessel as
having been built about A. D. 900, for use in war by the great chieftain
whose tomb it became. The ship was 65 feet, 10 inches long, on the keel;
with an extreme length over all of 78 feet, 1 inch; amidships it was 16 feet,
9 inches; its depth amidships from the top of the bulwarks to the keel was 3
feet, 111⁄4 inches. The material throughout was pine. The helm, a plank
shaped like a broad oar, was fastened to the side of the vessel. In
accordance with the number of its oars and shields this ship must have had
a crew of sixty-four, besides these came the steersman, the chieftain and
probably a few more of his companions, making a total, in all likelihood, of
seventy to be carried by her. Says Mr. Nicolaysen: “In the opinion of
experts this must be deemed a masterpiece of its kind, not to be surpassed
by aught which the shipbuilding craft of the present age could produce.
Doubtless, in the ratio of our present ideas, this is rather a boat than a ship;
nevertheless in its symmetrical proportions, and the eminent beauty of its
lines, is exhibited a perfection never attained until after a long and dreary
period of clumsy unshapeliness, when it was once more revived in the
clipper-built craft of the nineteenth century.”[5]
[5] A detailed description of the Viking Ship is given in the “Transactions of the Institute of
Naval Architects”. (London), Vol. XII, p. 298.

CLIPPER SHIP “YOUNG AMERICA.”
Length of deck, 235 feet. Beam molded, 40 feet, 2 inches. Depth of hold, 25 feet, 9 inches.
Tonnage, 2900.
Enlarged illustration (85 kB)

Thirty to sixty years ago much of the world’s commerce Clipper Ships and
was borne by clipper ships. In all likelihood as good lines Modern Steamers.
as ever went into a vessel of this kind were displayed in
the Young America, outlined on page 58, built in 1853 for California and
East India trade. She once ran from New York to San Francisco in 103 days,

and from San Francisco to New York in 63 days, records which have never
been excelled. Her deck length was 235 feet; her depth of hold 25 feet, 9
inches; her moulded beam was 40 feet, 2 inches; her displacement was
2,713 tons. The lines worthiest of remark in her design are the diagonals
and buttocks, together with her easy entrance and run. Most clipper ships
were fuller forward than aft; this had two advantages: first, when forward
burdens, anchors and the like, tended to an undue settling down at the head,
it was well to increase the buoyancy forward; second, towing experiments
prove that a form slightly fuller forward than aft offers less resistance than
the reverse. This shape was hit upon by the old-time designers, doubtless as
a result of many a shrewd experiment.
In the early days of steamships, hollow or somewhat concave water lines
forward were in favor. Experiments with models have demonstrated that for
boats so full in section as to be nearly square, it is best to have forward lines
which are straight or nearly so. Recently it has been shown that at high
speeds, with a midship section nearly semicircular, resistance is a little
lessened by very slightly hollowing the water lines forward.
If a steamer is to have the utmost speed, as the Kaiser Wilhelm II, outlined
on page 60, her design will be very unlike that of a vessel required to carry
as much cargo as possible at a moderate or low speed, as in the case of the
steamship sketched on page 61. The dimensions of the Kaiser Wilhelm II
are:—length over all, 7061⁄2 feet; beam, 72 feet; depth, 29 feet, 61⁄4 inches;
displacement, 29,000 tons; speed, 231⁄2 knots; indicated horse power,
38,000. As we compare with her details of form the general features of our
cargo carrier, page 61, we observe in this freighter the full form of its water
lines, its almost straight and blunt entrance forward; we also notice that the
lower part of the bow has been cut away to avoid a reversal of curves which
would create an eddy with its consequent increase of resistance. Further we
may remark the squareness of the midship section, which means carrying
capacity at its maximum, together with the long parallel middle body, little
resisted by the water, ending aft in buttocks and water-lines quickly turned.
This is a twin-screw ship: of length 358 feet, 2 inches; beam, 46 feet; draft,
23 feet; depth from shelter deck, 34 feet, 8 inches; displacement, 8,270
tons; speed, 9 to 10 knots.

STEAMSHIP KAISER WILHELM II.
Length over all, 706 feet, 8 inches. Beam, 72 feet. Draft, 29 feet, 6.3 inches.
Displacement, 29,000 tons. Indicated horse-power, 38,000. Speed, 23.5 knots.
Enlarged illustration (60 kB)

TWIN-SCREW CARGO STEAMER.
Length, 358 feet. Beam, 46 feet. Draft, 23 feet. Displacement, 8270 tons.
Enlarged illustration (61 kB)

U. S. TORPEDO-BOAT DESTROYER.
Length over all, 246 feet. Beam, 22 feet, 3 inches. Displacement, 489 tons.
Speed, 30 knots.
Enlarged illustration (34 kB)

A good designer has an easy task in drawing lines for a freighter in which
the weight of hull, machinery and coals may be only 40 per cent. of the
displacement, leaving 60 per cent. for earning space. Contrast this with an
Atlantic flyer, where but 5 per cent. may remain for cargo. Here the
designer’s problems are difficult indeed, and the chief way out of them is to
enlarge his ship as much as he dares, for the bigger his vessel, its form and
speed unchanged, the less will be its resistance as compared with
displacement. But to an increase of size there are hard and fast bounds; first,

those imposed by the shallowness of channels and harbors; while the depth
of a ship is thus restricted, its length may be somewhat extended with safety
and gain; to increase of beam there are distinct and moderate limits, to
overpass them means that the ship will follow the wave contour of a heavy
sea so closely as to have a quick, jerky and dangerous motion.

Cross-sections of ships

To design a ship in this case and every other is plainly a
Judgment in Ship
matter of compromise, a quest of the optimum by a Design.
balancing of demands for safety, strength, speed,
capacity, handiness, good behavior in a sea-way, so that each invested dollar
may in the long run earn the largest return possible. Excellent examples of
judicious design are the best passenger steamers plying between Europe and
New York. Usually their section amidships is like that of a cargo vessel, but
for a special reason. Within the freighter’s walls the greatest feasible cross-
section must be created; so that the shape is box-like; in a high-speed
passenger ship the form is also square, because harbors are shallow; were
they less shallow the designer would choose a midship section somewhat
semicircular in contour. Were our harbors deepened, the easy sections of the

first transatlantic steamers could be repeated in their gigantic successors of
to-day, with increased speed for each horse power employed.
What a designer can do when his aim is swiftness at the expense of all other
considerations, is shown in the lines of the torpedo-boat destroyer, page 62.
Its length over all is 246 feet; length at water level, 240 feet, 10 inches;
beam, 22 feet, 3 inches; mean draft, 6 feet, 11⁄2 inches; displacement, 489
tons; speed, 30 knots. It is interesting to contrast, on page 63, the cross-
section amidships of this vessel, with similar lines of three other typical
vessels described in this chapter.[6]
[6] In writing these pages on the forms of ships I have been much indebted to Mr. Harold
A. Everett, Instructor in Naval Architecture, Massachusetts Institute of Technology,
Boston.
G. I.

CHAPTER VI
FORM—Continued. SHAPES TO LESSEN RESISTANCE TO MOTION

Shot formed to move swiftly through the air . . . Railroad trains and automobiles of somewhat similar
shape . . . Toothed wheels, conveyors, propellers and turbines all so curved as to move with utmost
freedom.

hile ships are much the largest structures built for Projectiles and
W motion, and therefore meet resistances which the Vehicles of Like
designer must lessen as best he may, other Pattern.
moving bodies, small as compared with ships, encounter
resistances so extreme that their reduction enlists the utmost skill and the
most careful study. Speeds vastly higher than those of ships are given to
projectiles. A ball leaving a gun muzzle with a velocity of 3,410 feet a
second, as at Sandy Hook in January, 1906, suffers great atmospheric
resistance, overcome in part by the shot having a tapering or conoidal form.
Indians long ago stuck feathers obliquely into arrows so as to keep flight
true to its aim by giving shafts a spiral motion; an attendant advantage
being to lengthen flight. The same principle appears in rifling, that is, in
cutting spiral grooves in the barrels of firearms large and small, a missile
receiving a spinning motion through its base, a thin protruding disk of soft
metal, forced into the grooves by the explosive. At first the grooves in
firearms were straight with intent to preclude fouling; spiral grooves were
introduced by Koster of Birmingham about 1620. Delvigne, a Frenchman,
devised a lengthened bullet narrower than the bore so as to enter freely,
under the pressure of firing it completely filled the bore, rotating with great
velocity as it sped forth.

Racing automobile. Wedge front and spokeless wheels.

Now that railroad speeds are approaching those of projectiles, the outlines
of trains are resembling those of shot and shell. In the experiments with
very fast trains at Zossen, in Germany, October, 1903, each car had a
paraboloidal front, much diminishing the resistance of the air. Racing
automobiles are usually encased in a pointed shell which parts the air like a
wedge; their wheels, too, are supported not by spokes, but by disks having
no projections. As electric traction becomes more and more rapid in its
interurban services, the cars will undoubtedly be shaped to lessen
atmospheric resistance. Especially is this desirable in a tunnel service, such
as that of the New York Subway, where the resistances are extreme for the
same reason that a boat in a canal is harder to draw than if in water both
broad and deep. Just as in ship-design, it is in sharpening the front and rear
of a car or a train that most economy is feasible; the friction at the sides
cannot be much lessened except, in the case of a train, by joining each car
to the next by a vestibule such as that of the Pullman Company.
Electric traction finds gain in a track having in places a decided inclination.
In the monorail line between Liverpool and Manchester a downward dip in
the line at each terminal quickens departure, and in arrival aids the brakes
by checking speed on the up-grade. In the swift motion of ordinary
machinery the resistance of the air is a source of considerable loss. By
encasing a heavy flywheel in sheet iron so as to present a smooth surface to
the atmosphere, M. Ingliss has saved 4.8 per cent. of the energy of a 630
horse power engine.

Bilgram skew gearing.

In the simplest machines motion may be transmitted by Gearing:
wheels in contact, faced with adhesive leather, rubber, or Conveyors.
cloth. Teeth, however, are usually employed; as wear
takes place they permit a little play, a slight looseness, which contact
wheels altogether refuse. Toothed wheels have the further advantage that
they do not slip, their motion is positive. How teeth may best be contoured
involves nice questions in geometry. They should always push and never
grind each other, and should move with the least possible friction. In some
ingenious designs the teeth of any one particular wheel of a series will
enmesh with the teeth of any other wheel, no matter how much larger or
smaller. Bevel gears cut by Mr. Hugo Bilgram, of Philadelphia, turn with
hardly any friction whatever, although in some wheels the teeth run askew,
or are sections of cones which do not meet at their apices. The Bilgram gear
cutter, and the Fellows’ gear shaper which turns out plain gear, exert a to
and fro planing action. Ordinary gears are cut on milling machines by rotary
cutters, or may be manufactured on a Bliss press without cutting the
original lines of fibre. The importance of accurate and easy-running gears
increases steadily; they are, for example, applied to steam turbines whose

velocity must be reduced in the actuation of ordinary machines.
Automobiles and bicycles also demand reducing gear running with the
utmost freedom.

Grain elevator.

Robins conveying belt of rubber moved on rollers.

The grain elevator, invented many years ago, is the parent of manifold
conveyors of coal, lime, ore or aught else. Their receivers have links shaped
so as to extend for hundreds of feet as continuous belts. Link belting may be
had in detachable sections, fitting each other at secure hinges which allow
free motion.
The Augustin B. Wolvin, a typical ore-carrier on the great lakes, is 56 feet in
depth; its hold is curved to allow a clam-shaped bucket to seize ten tons of
ore at each dip. It is probable that at no distant day rapid transit in cities will
employ continuous moving platforms, just as conveyors and telpherage
systems are taking the place of the discontinuous transport of grain, coal,
cotton, ore, and heavy merchandise.

Ewart detachable link belting.

The screw, an inclined plane wound about an axis, forms the
Propellers.
propeller for steamships and many steamboats. There is a good
deal of debate as to the principles which should decide its best
lines. Here evidently is a field which will handsomely repay thorough
investigation. The power expended in steamships, whether fast or slow, is
prodigious; any marked improvement in the contour of screws will mean
either a saving of fuel or an increase of speed. Of equal importance with
water-propulsion is the setting in motion of air. In blast furnaces enormous
volumes of air are forced at high pressure into the fuel and ore: the fans are
carefully molded in screw form, any departure from the best curves
entailing serious loss. Fans for less important services are seldom shaped
with care and usually waste much energy.

Allied to screws are turbine wheels, much the most efficient of
Turbines.
water motors. The shaping of their vanes as volutes minimizes
the loss of energy in shock as the water comes in, and lessens to
the utmost the velocity of the stream as it leaves the wheel. Now that steam
turbines are scoring a success both on land and sea the contouring of their
vanes with extreme nicety is an important problem of the engineer. A
perfected form means the highest economy.

Curves of turbines.
Niagara Power Co.

It is interesting to note how the screw propeller, the fan, and the turbine
wheel have each led to a converse invention. Mr. Edwin Reynolds, of
Milwaukee, has devised a pump in screw form of capital efficiency under

low heads. The fan has long had its converse in the windmill, now more
popular throughout America than ever before, mainly because shaped with
new excellence. In the best models, built of steel, the sails are each a section
of a volute carefully designed to discharge the wind evenly, just as in the
parallel case of emission from a water mover, such as the Worthington
pump. This capital pump is simply a turbine wheel reversed. Its impeller
and diffusion vanes take up water from rest, lift it to a height which may be
as much as 2,000 feet, and then deliver it at rest, with little loss from
internal eddies or slippage.

Steel vanes of wind-mill.
Fairbanks, Morse & Co., Chicago.

The Pelton wheel, pre-eminent among water-motors of the impulse type,
owes its economy chiefly to each bucket being divided in halves and curved
with the utmost nicety.

Pelton water wheel.

Jet for Pelton wheel.

CHAPTER VII
FORM—Continued. LIGHT ECONOMIZED BY RIGHTLY SHAPED
GLASS. HEAT SAVED BY WELL DESIGNED CONVEYORS AND
RADIATORS

Why rough glass may be better than smooth . . . Light is directed in useful paths by prisms . . . The
magic of total reflection is turned to account . . . Holophane globes . . . Prisms in binocular glasses
. . . Lens grinding . . . Radiation of heat promoted or prevented at will.

hese are times when an inheritance, such as the
T window pane, venerable though it be, is freely
criticized and shown to be far from perfect. We
A Shrewd
Observer
Improves
Windows.
find, indeed, that surfaces and forms long given to the
glass through which light passes, or from which light is
reflected, are faulty and wasteful. This means that sunshine can be turned to
better account than ever before, that artificial light can be employed with an
economy wholly new. A few years ago when we provided a window with
plate glass, smooth enough for a mirror, nothing better seemed possible.
Thanks to the late Edward Atkinson, of Boston, we know to-day that in
many cases glass may be too smooth to give us the best service, that often
we may get much more light from panes of rough, cheap make than from
costly plate glass. He tells us: “In 1883, when I inspected a large number of
English cotton mills, I found them glazed with rough glass of rather poor
quality, the common glass of England being inferior to our own from the
general lack of good sand. On asking why rough glass was used instead of
smooth I was told that rough glass gave a uniform and better light. To my
astonishment I found this true. The interior of a mill so lighted had the
aspect of diffused illumination. This led me to reason on the subject. I
looked into the construction of the Fresnel lens, in which a combination of
lenses and curved surfaces concentrates rays of light into a single far
reaching beam. I reasoned that if one set of angles or curves could thus
concentrate light, then by reversal of such angles or surfaces, light could be
diffused.”

Mr. Atkinson proceeded to gather specimens of glass not only of common
rough surface, but also in ribbed and prismatic forms. These he handed for
examination and comparison to Professor Charles L. Norton of the
Massachusetts Institute of Technology, Boston. His report says: “The
hopelessness of trying to get something for nothing, that is, to get a sheet of
window glass to throw into a room more light than fell upon it, appeared so
plain to me that I made all my preparations to measure not a gain but a loss
of light in using Mr. Atkinson’s samples. The results of the tests may be
briefly stated: In a room thirty feet or more deep we may increase the light
to from three to fifteen times its present effect by using ‘Factory Ribbed’
glass instead of plane glass in the upper sash. By using prisms we may,
under certain conditions, increase the effective light to fifty times its present
strength. The gain in effective light on substituting ribbed glass or prisms
for plane glass is much greater when the sky-angle is small, as in the case of
windows opening upon light shafts or narrow alleys. With the use of prisms
a desk fifty feet from a window has been better lighted than when but
twenty feet from the same window fitted with plane glass. . . . ‘Ribbed’ and
‘Maze’ glass are of very great value in softening the light, especially when
windows are directly exposed to the sun, aside from their effectiveness in
strengthening the light at distant points. With the ‘Maze’ glass the artist may
have, in all weathers and in all directions, what is in effect a much-desired
north light. The same glass provides the photographer with light as well
diffused as when cloth screens or shades are employed and of much greater
intensity.”
Plate prism glass is now manufactured with its outer or street surface
ground and polished like plate glass, with its prisms accurate and smooth.
In dimensions which may reach fifty-four by sixty inches it affords surfaces
easily kept clean, and transmitting much more light than glass held in
frames of small divisions.
Whence the gain in thus exchanging plane glass for glass rough, ribbed, or
prismatic? Rays streaming through an ordinary window strike nearby
surfaces of wall, ceiling, and floor; from these they are reflected in large
measure and return through the glass to outer space. Rough, ribbed, or
prismatic glass throws the rays much further into the room, hence they
strike so much larger an area of wall, ceiling, and floor that in being
reflected again and again the light is well diffused, and but little is sent forth

again into outside space. The form of the glass gives the entering light its
most useful direction, so that the new panes serve better than the old. This
effect is most striking when prisms are carefully adapted to a particular case
in both their angles and their placing. In traversing glass, light is absorbed
and wasted, so that the shorter its path the better. In the compound lens
devised in 1822 for lighthouses by Augustin Jean Fresnel, light is as
effectively bent by the part of the glass shown in dark lines as if the whole
lens were employed.

Luxfer prism.

Fresnel lens.

This brings us to means for the best use of artificial light. Within the past
thirty years the standard of illumination, thanks to electricity, has steadily
risen. More important than ever, therefore, is it that light should be
employed pleasantly and effectively. This in the main is a question of
placing the sources of light judiciously, and of so reflecting and refracting

their rays that they will be of agreeable quality, and arrive where they are
wanted with the least possible loss. Reflectors rightly shaped and kept clean
economize much light. For lack of them in streets and squares we may
sometimes observe half the rays from a lamp taking their way to the sky
where they do no good. In shop windows ribbed reflectors throw full
illumination on the wares displayed, while the sources of light are out of
view. The same method is employed in art galleries and in museums. A
parabolic reflector sends forth as parallel rays the powerful beam of a
lighthouse, a locomotive, or a searchlight. An incandescent lamp of
ingenious design is silvered on its upper half so that none of its light is
wasted. Because the arc lamp is the cheapest of all illuminants it is adopted
for out-of-door lighting where its unpleasant glare is tempered by distance.
In factory lighting its brightness is excessive and harmful unless moderated.
A capital plan is to employ an ordinary continuous current and place the
positive carbon, with its brilliant centre, below the negative carbon; beneath
these two carbons a good reflector throws the rays to the ceiling, whence
they descend with agreeable diffusion and much less loss than when globes
of ground glass surround the arc. A common white ceiling when quite flat is
an excellent reflector; indeed, a sheet of white blotting paper returns light
nearly as well as a polished mirror, and for many purposes it serves better;
the mirror sends back its beam in a sharply defined area which may be
dazzling, the paper scatters light with thorough and agreeable effect.

Lamp and reflector a unit.

Inverted arc-light.

Usually a mirror is a sheet of highly polished metal, or a plate of glass with
a quicksilver backing; preferable to either is clear glass, all by itself, so
formed as totally to reflect an impinging beam of light. To understand the
principle involved in its use we will for a little while bid good-by to lamps
of all kinds.
A hall of delights is the New York Aquarium, in the
Delight and Gain
historic Castle Garden at the Battery. Its tanks display a as We Watch a
varied and superb collection of fish, whose beauty of Fish in Water.
form and color heightened by swift and graceful motion,
fascinates the eye as no museum of dead things, however splendid, ever
does. When a tank is still, or nearly still, and a gold-fish or a perch is
quietly resting near the surface of the water, one may see its form reflected
from that surface as perfectly as if by a mirror. The point of view must be
close to the tank, with the eye somewhat lower than the fish. So perfect, at
times, is this mirroring that young folks are apt to suppose the reflection to
be a second fish, and they are puzzled to remark how strangely it resembles
its mate just below. What explains this reflection? A ray of light can always
pass from a rare medium, such as air, into a dense medium, such as water,

because it is bent toward their common perpendicular. But a ray cannot
always pass from a dense into a rare medium, from, let us say, water into
air, for if the ray were to be bent away from the common perpendicular
more than 90° it would altogether fail to emerge from the water. No
luminous ray can pass from water into air if it makes a greater angle with
the perpendicular than 48° 35´. Suppose AB (page 78) to be the water level
of a tank. A ray leaving F will be bent so as to reach C, a ray from G will
reach D, a ray from H will reach E; but a ray from L will be bent so much
as to pass along the surface of the water as OB, and a ray from I will be
bent so as to return beneath the surface of the water to I. Rays such as I,
undergoing total reflection, afford us our second image of a fish at rest near
the surface of water: to observe this kind of image we need not journey to
the New York Aquarium; with patience we may behold it in a small home
aquarium with flat sides of clear glass, waiting until the water is quiet and a
fish comes close to the surface.

Sacramento perch totally reflected in aquarium.
A, surface of water.

Every dense transparent substance has this ability to yield images by total
reflection, each substance having a critical angle of its own; we have just

seen that for water this angle is 48° 35´. Glass is made in many varieties,
each with a special critical angle, never much different from that of water. A
right-angled prism of glass, which any optician can supply, serves as a
capital mirror for rays striking its surface at ninety degrees. Such prisms are
employed in opera glasses, in hand telescopes, in reflectors for light-houses,
and in the Holophane globes we are about to examine. The efficiency of
these prisms may be as much as 92 per cent., whereas that of the best
silvered mirrors never exceeds 90 per cent. The loss in a prism is due to a
slight reflection by the surface on which the rays first fall, and by the
absorption of light in the glass itself; this second loss, of course, increases
with the thickness of the prism.

AB water level. F, G, H, L are refracted to C, D, E, B.
I is totally reflected to I.

Holophane globe, vertical section.

Section of Holophane globe.
Ray A is refracted as A´, C as C´. B, totally reflected, then refracted,
emerges as B´. D takes a similar course, emerging as D´.

Now that we understand the principle of total reflection, Total Reflection in
let us see how it is applied to increasing the effectiveness Artificial
of a Welsbach mantle or an electric lamp. And first let us Lighting:
Holophane
say that we may wish light upon a small area, mainly in a Globes.
single direction, as downward upon a desk or reading-
chair. Or, in a quite different manner, if we are to illuminate a wide space
such as that of a large parlor. These requirements are fulfilled by the
Holophane globes, devised by M. Blondel and M. Psaroudaki, which are
made in many shapes, each adapted to a specific duty. The upper half of
each globe is formed into prisms of such angles that, zone by zone, the
glass totally reflects impinging rays in just the directions desired. The
contouring is accurate to the thousandth part of an inch. With this thorough
reflection is combined diffusion as thorough, the interior of the globe being
shaped as ribs. Thus, with the least possible waste, the upper half of the
source of light is utilized. What of the lower half? Its rays pass through
prisms formed so as to refract impinging light into desired paths with but
little loss. As a whole, therefore, these globes furnish a beautiful means of
illumination with all but perfect economy, special forms of them sending
light in any direction desired.

Diffusing curves.
Holophane globe. Rays are split into b, e, reflected, then
as e, f, g, refracted; and into b, c, d, refracted.

Class A, Class B, Class C,
Holophane globe, rays mainly directed at an casting rays chiefly in a
throwing rays mainly angle of 60°. lateral direction.
downward.

Section of Holophane globe and Welsbach mantle, showing distribution of light.
Each typical ray as refracted is marked by a letter of its own.

In the Zeiss Works at Jena, in Germany, optical Total Reflection in
instruments of the highest excellence are manufactured; Binocular Glasses.
many of these take advantage of the principle of total
reflection we have been considering. When the task was assumed of
producing a new and improved telescope, it was observed that an ordinary
telescope, built up of lenses, is inconveniently long and heavy in

comparison with its magnifying power. The question arose whether it was
possible to construct short instruments of a magnifying power of four to
twelve diameters. Porro, an Italian, about the middle of the nineteenth
century suggested totally reflecting prisms so placed that while the total
travel of a ray would be the same as in an ordinary telescope, the two ends
of the luminous path would be near together, while the whole would be
more effective than if four mirrors were employed. His idea may be
represented by a wire one meter long so bent that its ends are much less
than one meter apart. In an illustration of a field-glass as manufactured at
the Zeiss Works, on the Porro principle, it will be remarked that the entering
ray passes through lenses which are farther apart than the lenses which form
the eye-pieces. Thus a much wider field is viewed than that of an ordinary
glass, while as the two images received from the two eye-pieces differ more
than those observed in direct vision, the perception of depth is increased in
a notable degree. This construction is adapted to sporting, marine, and
opera-glasses, as well as to field-glasses.

How a wire may be shortened while its original direction
is resumed.

Four mirrors, 1, 2, 3, 4, reflect a ray in a line parallel to its
original path.

Prisms for Zeiss binocular glasses.

Lenses nevertheless continue to be much more important
Lenses Still Much
than prisms, and the proper shaping of their surfaces Used.
involves high reaches of both science and art. The
properties of the glass, of course, count for most in producing combinations
free from color for telescopes, microscopes, and cameras. Jena glass,
described in another chapter of this book, with its extraordinary range of
refractive and dispersive qualities has brought optical instruments to virtual
perfection. Meanwhile the arts of lens-grinding leave little to be expected in
the way of future improvement. It is astonishing that a lens forty-two inches
wide can be so truly curved as to focus the image of a star as an
immeasurable dot.

Zeiss binocular glasses: longitudinal and cross-sections.

Let us look at some of the instruments designed by a
The Production of
master for shaping glass discs into lenses. Some of the Optical Surfaces.
best telescopes in existence are from the hands of Mr.
John A. Brashear, of Allegheny, Pennsylvania. The grinding tools he
employs he has contoured in such wise as to produce desired curves free
from error. The first polishers are of the ordinary form with square or
circular facets equally distributed over the surface of the tool, as in Figs. H
and 8. When the polish is brought to its best, the glass is allowed to cool
slowly to a normal temperature, and is then carefully studied as to its
defects. These are removed and the surfaces finished with iron tools, of the
same diameter as the surface to be worked, each tool being laid off into six
sections, as in Figs. 3, 4, 5, 6, 7. The tool being warmed, pitch is spread
over its leaf-like spaces, which are given the proper curve by being pressed
down on the previously wetted concave surface; the pitch and tool are next
quickly cooled with water. In the shaping of these spaces rests success. The

zone, a, a, in the first figure, needing the greatest amount of abrasion, meets
the widest part of the leaflet, but in order that no zonal error may be
introduced, as in b, c, c, b, of the second figure, it is gently tapered in each
direction, the amount of taper being governed by the lateral stroke given to
the polisher, as well as by the amount of departure of the zone from the
normal curve.

Tools for producing optical surfaces.
John A. Brashear, Allegheny, Pa.

But after all the astronomers aided by lenses thus carefully shaped are few,
while millions of people suffer from defects of sight which are overcome by
suitably formed spectacles.
In this field a recent minor improvement is worthy of
Bi-focal
mention. Benjamin Franklin many years ago made a pair Spectacles.
of spectacles in which the upper half of each glass was
ground for far seeing, the lower half for near seeing. To-day such bi-focal
spectacles are not made in halves, with an unpleasant broken line across
them. In each of the new eyeglasses toward the base a small lens of dense
quality is enclosed; through this lens a wearer looks at objects nearby;

through the upper part of the eyeglass he looks at distant objects. The
joining of the three parts is effected so skilfully as not to be discernible.

Bi-focal lens for spectacles.

From light we pass to its twin phase of energy, heat, for a
Economy of Heat.
glance at the forms of devices which enable us to use heat
with economy. When we wish a furnace, crucible, or
cooking vessel to maintain the highest possible temperature, we give it as
little surface as possible. On the contrary when a warming apparatus is
devised, its surface is freely extended. The traditional fireplace, for all its
cheerfulness, yields but little heat. Benjamin Franklin copied its form in the
stove which bears his name; as it stands out from a wall it warms the air all
around itself, instead of on one side only. This model is familiar in gas
stoves, whose heat thoroughly radiated and convected far exceeds that
derived from fireplaces. In Canada forty years ago it was usual, especially
in the country, to set up gallows-pipes and dumb-stoves, or drums, bulky,
hollow structures of sheet iron, which obliged the heated products of
combustion to take a roundabout course as they passed to the chimney. To
be sure as thus cooled the gases were less effective as draft makers, but we
must remember that one of the most wasteful uses of fire is in warming air
or other gases for the sake of putting them in motion. In modern factories,

central lighting stations, and the like huge installations, mechanical draft
sends a quick current through a short chimney, saving much fuel. Excellent
in design are the tile stoves of Germany and Holland. Their gentle heat does
not parch the air; in moderately cold weather they render it unnecessary to
light furnaces which develop, at such times, unduly high temperatures.

Canadian box stove with gallows-pipe.

In factories the heating coils filled with steam or hot water were at first
fastened to the floor. Then came attaching them to the ceiling whence their
heat is gently radiated; on the floor the coils may gather dust and dirt with
risk of fire; with the other plan there is a saving of floor space, and
accidental leaks are at once in evidence.

Canadian dumb-stove.

Tubes for warming are specially effective when dented or buckled in
directions at right angles to each other and to the axis of the tube. This form
gives the heating water or steam a swirling motion which causes it to part
more rapidly with its heat than does a cylindrical tube of the same surface.
Gold’s electric heater for street-cars, bath-rooms, and the like, is a spiral of
resistant alloy, hung in a light metallic frame, the whole presenting a large
surface to the air. Automobiles driven by heat engines require coils of the
utmost possible surface whereat cooling can take place; in many cases this
cooling is furthered by the action of a quick fan. In like manner the
condensers of steam-engines, especially aboard ship, are made up of slender
tubes presenting to the steam a chilling area of vast extent.

Tubing for radiator.
Dalham Works, Manchester, England.

Gold’s electric heater.

Stolp wired tube for automobiles.

Inventors have long addressed themselves to the difficulty caused by the
expansion and contraction of structures as temperatures change. For years
the cylindrical fire-boxes of marine boilers have been corrugated, so as to
allow them a certain play without breaking from their fastenings, or tearing
their seams, when heated or cooled. This form is adopted with success for
the Morison fire-boxes of the Vanderbilt locomotives. In quite different
situations metal piping, in a length of let us say 100 feet, is provided against
trouble from shrinkage or expansion by a U bend. When the diameter of the
pipe is twelve inches, this bend is usually about ten feet in extent; for a six
inch pipe, a bend six feet long suffices. Another difficulty due to heat is the
limitation of speed imposed by the heat which friction creates. A new type
of circular saw has a hollow arbor through which flows cold water, so that
motion may be faster than ever before. The same arbor appears in various
other machines with like advantage.

Corrugated boiler.

Pipe so bent as to permit contraction or
expansion.

CHAPTER VIII
FORM—Continued. TOOLS AND IMPLEMENTS SHAPED FOR
EFFICIENCY

Edge tools old and new . . . Cutting a ring is easier than cutting away a whole circle . . . Lathes,
planers, shapers, and milling machines far outspeed the hand . . . Abrasive wheels and presses
supersede old appliances . . . Use creates beauty . . . Convenience in use . . . Ingenuity may be
spurred by poverty in resources.

e have just reviewed, all too briefly, how light
W and heat are economized by structures of
judicious form. At this point we will bestow a
Tools and
Implements.

rapid glance at the economy of work as promoted by sound design in tools
and implements, in the machines which embody these for tasks far beyond
the personal skill or power of the strongest and deftest mechanic.
When of old a savage took up a stone to serve as a rude knife or chisel, we
may be sure that he chose the sharpest flint he could find. If he could better
its shape by knocking it into something like a wedge, what task was easier?
Our museums display an immense variety of stone hammers, axes, knives,
and arrowheads, showing how art long ago improved the forms of simple
tools and weapons offered by nature. Modern tools and weapons, for all
their immense diversity, were every one prefigured in the rude armory of
primitive man.
Descended from his flint knife is the abounding variety of steel cutting tools
all the way from the razor, concave on both sides, to the axe, doubly
convex. As the arts have become more specialized, as artificial power has
been introduced, the contrasts of the form of one tool with another have
grown more and more striking. The bar which slices metal is stout of build,
and rectangular in section, while a lancet is little wider or thicker than a
blade of grass. The knives which divide leather, rubber, and rope, differ
much from one another; the knife which separates the leaves of a book
serves best when dull. Gouges for carving are nicely adapted to the profiles
they are to cut; while the exigencies of the power-lathe require its tools to
be designed of particular strength and rigidity. Among revolving hand-tools

the brace is the most important, enabling the workman to exert great
leverage. A minor tool, the gimlet, was formerly more in use than to-day.
Now that screws are made with gimlet points they break their own paths.

Carving chisels and gouges.

Lathe cutters.

Ratchet bit brace.

From the beginning tool-makers have shown skill in fitting a tool to the
hand, as in the Eskimo skin-scraper; this simple adaptation may have
arrived in copying the effect of wear. Other good hints have come from
observing an implement after its work is done. At the places where mud
clung to a plowshare the plow-maker was long ago told at what points to
raise his metal; conversely, when a cutter of any kind is unduly worn at any
part of its side, there the metal asks to be somewhat narrowed down.

Eskimo skin scraper.

Double tool drill cutting boiler plate.

A circle of say two feet in diameter, may be readily cut from a boiler plate
by two cutters, one at each end of a horizontal bar, the bar being supported
by a central upright axis receiving the motive power. Because the cut is
narrow, but little metal is wasted as chips. A cut of this ring-shape effects a
desirable saving even when the circle to be swept is but an inch or so in
width instead of several feet. When an auger takes its way through a plank
it removes as chips all the wood within the circle of its range; a drill, of
common form, as it pierces stone or metal acts in a similar manner. Motive
power is greatly economized when a drill is tubular, with the further
advantage that within the ring cut a solid cylinder remains to be broken off
at intervals and lifted out, its core informing to the engineer in quest of bed-
rock, to the prospector of mines or oil-fields, or to the geologist who reads
at a glance the composition of a mineral, the forces which have impressed it
age after age. Such drills, set with bortz diamonds, have accomplished
remarkable feats. In boring out 260 columns surrounding the dome of the
capitol at Springfield, Illinois, cores 223⁄4 inches in diameter were removed
from holes 24 inches wide; without sacrifice of strength there was a saving

A common drill removes a A ring drill removes much
whole circle of stone. less stone with the same
effect.
in weight of three-fifths. At the
Ellenwood coal mine, Kingston, Pennsylvania, a core 17 Annular Drills.
feet, 5 inches in breadth was taken from a bore only five
inches wider. When the engineers in 1896 were planning the foundations for
the Williamsburg Bridge, New York, the deepest of their 22 borings was
112 feet below high water. Steel drills had indicated bed-rock 12 to 20 feet
higher than was the actual case; the diamond drill showed the supposed
bed-rock to be merely a deposit of boulders. No other known means could
have accomplished these results. In the same way steel guns of large calibre
have been drilled so as to leave a core of much value, while in this as in all
other such tasks, the boring demanded less energy and proved less straining
than if all the metal within the sweep of the drill had been reduced to
fragments. All these tools were prefigured in a simple ring drill used two

thousand years ago on the banks of the Nile; hollow reeds were employed,
with sand as a cutter.

Twist drill.

Twist drills are superseding flat drills as stronger and better in Twist Drills.
every way. A twist drill is made with a slight taper toward the
shank end. Its cross-section is not quite round, the diameter
being reduced from a short distance behind the cutting edge, so as to
diminish friction and give the sides of the drill as much clearance as
possible. The advanced edges of the flutes are all full circle, so as to
maintain the diameter of the drill and keep the tool steady. The advantage of
the twist drill is that its cuttings find free egress, while it always runs true,
without reforging or retempering. The cutting edges are usually ground to
an angle of sixty degrees to the center line of the drill; for brass work the
angle should be fifty degrees.
The manner in which a lathe tool cuts metal is shown in Lathe and Planer
an outline which represents a tool feeding a cut along a Tools.
piece of wrought iron. The removed metal, in its
diameter and openness, tells the expert operator both the quality of his
cutter and how it is being affected by wear. The principal consideration,

says Mr. Joshua Rose, in determining the proper shape of a cutting tool, for
use in a lathe or a planer, is where it shall have the rake, or inclination, to
make it keen enough to cut well, and yet be as strong as possible; this is
governed, in a large degree, by the nature of the work.

How a tool cuts metal.
Beginning a second cut.

Dacotah fire-drill.

In giving form to wood and metal cheaply and rapidly,
Machine Tools:
machine-tools have within recent years risen to great Lathes.
importance. Of these the lathe is one of the chief. It

seems to be descended from the bow drill, the tool which was whirled by a
cord wrapped round it, or it may be, that under another sky, the lathe was
derived from the potter’s wheel whose axle was changed from a vertical to
a horizontal plane. For centuries all lathes had their cutting tools simply laid
on a bar, or rest, just as in the hand cutting lathe of to-day. While this
afforded opportunity to skill it did not lend itself to large or uniform
production. Henry Maudslay, about a century ago, immensely broadened
the machine in scope by devising the slide rest which firmly grasps the
cutting tool, and automatically moves it toward or away from the axis of the
work, as well as along the work in any desired line. This device is equally
applicable whether in turning a pencil case, the granite columns for a
cathedral, or the propeller-shaft of an ocean steamer.

Lathe: a, work; b, tail-stock; c, hand-tool rest; d, dead-centre; e, live-
centre; f, face-plate; g, live-spindle; h, dead-spindle; k, head-stock; m,
cone-pulley; n, driving-pulley; o, belt; p, treadle; r, treadle-hook; s, shears;
t, treadle-crank.

Compound slide rest.
C, shears; E, tool carriage; H, cross slide; K, cross slide handle; L, cross feed
handle; P, tool post; T, tool; D, driver; W, work.

Blanchard Lathe.
A, frame; B, carriage; C, gun stock; D, former; E, cutter-head; F, guide wheel; G, swinging frame;
H, feed motion; K, shaft for revolving stock and former.

The lathe has been developed in many ways until it has become one of the
most complex of all machines, adapted to tasks which even twenty years
ago seemed impossible. Only two of its varieties can here be noticed, the
Blanchard lathe for cutting irregular forms, and the turret lathe. An
illustration, taken from an old engraving shows the Blanchard lathe as
originally built for shoe-lasts. A pattern-last and the block to be carved are
fixed on the same axis and are revolved by a pulley. On a sliding carriage
are fastened pivots from which are freely suspended the axles of a cutting
wheel, and a friction wheel, equal in diameter. The cutting wheel turns on a
horizontal axle, and bears on its periphery a series of cutters. The friction
wheel is in contact with the pattern-last and presses against it while in
motion. During revolution, the pattern, irregular in its surface, causes the
axis to approach or recede from this friction wheel; the cutting wheel in its
corresponding motion removes wood from the block until a duplicate of the
pattern appears. This lathe much improved and modified now turns not only
gun-stocks, axe-handles and the like, but repeats elaborate carvings with
precision. Ornaments for Pullman cars are produced by this machine.

Turret lathe: an early Brown & Sharpe model.
C, carriage; T, turret; L, hand lever; F, face plate; D, jaw chuck; E, tool.

Turret of turret lathe.
Side view. Top view.

The turret lathe, equally ingenious, has a turret or capstan, which carries let
us say eight different tools, one on each of its eight faces. In its turn each
tool operates on the work in its forward traverse; it then retires while the
turret automatically moves through one-eighth of a circle, when the next
tool emerges for its task, and so on.[7]
[7] The turret principle is embodied in drills and a variety of other machines. It was
adopted in remarkable fashion by John Ericsson in his Monitor, launched in 1862 for
service in the Civil War. Because this vessel had to navigate shallow streams, its draft was
limited to eleven feet. As it was thus impossible to carry the burden of armor necessary to
protect a high-sided vessel, he was obliged to design a sunken hull. Guns and gunner were
protected within a covered cylindrical turret which as it turned on its vertical axis,
delivered an all-round fire while the Monitor stood still. Ericsson’s original turret, and its
later modifications in the leading navies of the world, are described in the Life of John
Ericsson, by William Conant Church, New York, Scribner, 1890.

Ericsson’s Monitor.

Lathes have given rise to planers, now built of great strength and in highly
complicated designs. In a lathe the object turns upon centers against a tool;
a planer carries its tool in a revolving cylinder, the work being fed in a
straight line. A shaper, with much the same essential construction, moves
along its work, the wood or metal operated on remaining stationary. With a
planer or a shaper the size and uniformity of the work depend upon the skill
of the operator. The planer has led to the invention of a machine which
dispenses with this skill. Bramah, in 1811, employed a revolving cutter to
plane iron, adapting to metal the familiar mechanism for planing wood.
This was the beginning of the milling machine, now so remarkably
developed and improved. A skilled mechanic sets the machine and the
chucks which hold the work; an unskilled hand can continue the operations,
his products being uniformly of the dimensions and forms desired. Intricate
shapes are easily executed, quite impracticable on any other machine. At
first the revolving mechanism and its cutters were a single piece of metal;
to-day cutters of costly quality are inserted in cheap metal; these inserted
cutters when worn out are easily replaced.

Iron planer; a, b, c, d, fixed cutting tools; M, moving bed.
Niles-Bement-Pond Co., New York.

Iron shaper: a, b, fixed cutting tools. K, M, traveling bars.
Niles-Bement-Pond Co., New York.

Milling machine, R. K. Le Blond Machine Tool Co., Cincinnati.
A, table; B, overhanging arm; C, cutters; D, spindle; E, feed box.

In many cases the milling machine ousts the planer as much more
economical. At the shops of the Taylor Signal Company, Buffalo, a miller of
the Cincinnati Milling Machine Company does nine-fold as much work as a
planer. It takes a first cut 1⁄8 inch deep across a full width of 12 inches,
makes 60 revolutions per minute, feeds .075 inch per turn, giving a table
travel of 41⁄2 inches per minute, with an accuracy limit of .001 inch.

Milling cutters with inserted teeth.
Cincinnati Milling Machine Co.

Now for a glimpse of what a great inventor had to suffer because he lived
prior to the era of machine tools, before the days, indeed, of that
indispensable organ of the lathe, its slide rest. The first steam engines of
James Watt built at the Soho Works, near Birmingham, are thus
described:—“A cast iron cylinder, over 18 inches in diameter, an inch thick
and weighing half a ton, not perfect, but without any gross error was
procured, and the piston, to diminish friction and the consequent wear of
metal, was girt with a brass hoop two inches broad. When first tried the
engine goes marvelously bad; it made eight strokes per minute; but upon
Joseph’s endeavoring to mend it, it stood still; and that, too, though the
piston was helped with all the appliances of hat, papier maché, grease,
blacklead powder, a bottle of oil to drain through the hat and lubricate the
sides, and an iron weight above all to prevent the piston leaving the paper
behind in its stroke—after some imperfections of the valves were remedied,
the engine makes 500 strokes with about two hundred weight of coals.” In
another month or two, with better condensation, it “makes 2,000 strokes
with one hundred weight of coals.”

Milling cutters executing complex curves.
Brown & Sharpe, Providence, R. I.

Emery, carborundum and alundum wheels are developed Emery and
from the grindstone of the distant past. That stone gives a Carborundum
straight-line finish or edge to the surfaces submitted to it; Wheels.
and as the work is shifted in front of the stone these
surfaces may take a curved or other contour. But a grindstone, let it be as
hard as can be found, is not hard enough to take and keep any other than a
cylindrical form. Its successors of to-day, the carborundum wheel
especially, can be of varied shapes, and transfer these to metal with celerity
and economy.
Carborundum, a compound of silicon and carbon, is produced at Niagara
Falls, New York, by a process devised by Mr. E. G. Acheson. In an
electrical furnace are placed granulated coke, sand, a little salt, and some
sawdust to keep the mixture porous and allow generated gases to escape
freely. The crystals of carborundum thus produced require seven horse-
power hours for each pound; in hardness they are excelled by the diamond
only. United under severe hydraulic pressure by a vitrified bond they are
eight times as efficient as emery in abrasion. Carborundum wheels are
replacing lathes as a means of finishing axles, piston-rods and rolls; their
accuracy is unsurpassed, while they demand but one third the time needed
by a steel tool.

Emery wheels.

Carborundum Co., Niagara Falls, N. Y.
Carborundum wheel edges.

At the very dawn of art moist clay was molded into
Form in Plastic
useful plates and bowls. This foreran not only all that the Arts.
potter has since accomplished, but all that has been

achieved in the foundry and the mint. In making bricks, tiles, and terra
cotta, the first task is to make the clay plastic, then advantage is taken of its
plasticity. In like manner we heat a metal to fluidity, and then pour it into a
mold to make a fence rail, a stove plate, or a car wheel. An electric bath
refines upon this process. Copper, let us say, dissolves in a tank, and
concurrently its particles are deposited on a mold from which the metal can
be readily stripped, avoiding the distortion inevitable when heat has come
into play.
Within the past ten years concrete has grown into much importance as a
building material, especially as reinforced with steel. It is a great deal easier
and cheaper to pour a wall into molds than to lay courses of brick, or cut
and dispose stone-work. Elsewhere in this book a few pages are given to
reinforced concrete, and its applications.
Pressing, like molding, has of late years much extended Pressing and
its range of forms. In germ it goes back to the distant day Stamping.
when seals were impressed upon clay tablets, and coins
or medals were struck from hard matrices. In glass manufacture the press
has been used for centuries. Cheap pressed tumblers and bowls have long
been accompanied by cheap metal pots and pans, plates and basins, stamped
by machinery. To-day much enlarged and improved, such machinery, as a
Bliss press, makes a kitchen sink from a sheet of steel, forms gears and
pinions from round bars of metal, and executes the intricate curves of a
mandolin in a plate of aluminum. For a good while the spinning lathe gave
us from thin metallic sheets a variety of cups, saucers, dishes, parts of
kettles, lamps, and the like. To-day each of these articles is produced by a
single blow of a die, proving that metals are plastic in a degree unsuspected
in former days. Thus it comes about that the seams necessary to the tinman
and the coppersmith, with all their liability to leaks and uncleanliness, have
been largely dismissed and may soon be wholly banished. Pressing is
illustrated on pages 184 to 186 of this book.
To-day we are rich in old and new facilities for the
Old and New
bestowal of form. To confer shape by division we have Means of
an immense variety of knives, scissors, saws, axes, Conferring Form.
hatchets and shears. These, together with hammers,
chisels and gouges enable us to disengage from a mass not merely a simple

rail, panel, or table-top, but a carving or a statue. Surfaces are smoothed
with a rasp, a file, a plane; sand is rubbed on abrasively, or falls from a
height, or is forcibly blown with a blast of steam or air. Emery either spread
on paper, or glued upon a wheel, grinds with an accuracy and speed new to
art; and all that emery can do is outdone by carborundum and alundum,
which slice away metal as if chalk, be its hardness what it may. Perforation
is accomplished with rotary drills, or by a sandblast, or on occasion by
corrosive acids—a final resource in treating refractory stone. Rolls of
tremendous power reduce iron and steel in thickness, and, when suitably
shaped, confer form on railroad rails, girders and the like. Every tool and
implement, old or new, is now embodied in machines of gigantic force, or
multiple effect, so that the skill of an earlier generation is either not in
demand at all or passes to tasks of a delicacy never attempted before. It is
by virtue of presses, enormous in power, that to-day shapes are bestowed on
metals in successful rivalry with the ancient art of the founder himself.
Indeed the art of conferring form by pouring a liquid into molds is at this
hour largely exercised in work where heat plays no part whatever,—as in
the tasks of the builder in concrete, the labors of the electrician as he
employs a bath to separate a metal from its ore, or to plate a surface with
silver or gold.

Diagram of rolls to reduce steel in thickness.

In strong contrast with the varied resources of modern Use Creates
toil are the simple tools and implements of prehistoric

skill which, modified much or little, are at this hour still Beauty.
indispensable to the mechanic, the builder, the engineer.
These simple aids early became admirable in form so as to be all the more
useful. Says Mr. George Bourne:—
“The beauty of tools is not accidental but inherent and essential. The
contours of a ship’s sail bellying in the wind are not more inevitable, nor
more graceful, than the curves of an adze-head or of a plowshare. Cast in
iron or steel, the gracefulness of a plowshare is less destructible than the
metal, yet pliant, within the limits of its type. It changes for different soils;
it is widened out or narrowed; it is deep-grooved or shallow; not because of
caprice at the foundry or to satisfy an artistic fad, but to meet the technical
demands of the expert plowman. The most familiar example of beauty
indicating subtle technique is supplied by the admired shape of boats, which
is so variable, says an old coastguardsman, that the boat best adapted for
one stretch of shore may be dangerous if not entirely useless at another
stretch ten miles away. And as technique determines the design of a boat, or
of a wagon, or of a plowshare, so it controls absolutely the fashioning of
tools, and is responsible for any beauty or form they possess. Of all tools,
none, of course, is more exquisite than a fiddle-bow. But the fiddle-bow
never could have been perfected, because there would have been no call for
its tapering delicacy, its calculated balance of lightness and strength, had
not the violinist’s technique reached such marvelous fineness of power. For
it is the accomplished artist who is fastidious as to his tools; the bungling
beginner can bungle with anything. The fiddle-bow, however, affords only
one example of a rule which is equally well exemplified by many humbler
tools. Quarryman’s pick, coachman’s whip, cricket-bat, fishing-rod, trowel,
all have their intimate relation to the skill of those who use them; and like
animals and plants adapting themselves each to its own place in the
universal order, they attain to beauty by force of being fit. That law of
adaptation which shapes the wings of a swallow and prescribes the poise
and elegance of the branches of trees, is the same that demands symmetry
in the corn-rick and convexity in the barrel; and that, exerting itself with
matchless precision through the trained senses of haymakers and woodmen,
gives the final curve to the handles of their scythes and the shafts of their
axes. Hence the beauty of a tool is an unfailing sign that in the proper
handling of it technique is present.”[8]

[8] Cornhill Magazine, London, September, 1903.

In the course of a judicious review of the mechanical engineering of
machine tools, Mr. Charles Griffin has this to say regarding convenience:—
[9]

[9] Engineering Magazine, New York, May, 1901.

“A tool is an investment, the interest which it earns Convenience in
depending on the amount of work it turns out in a given the Use of
time. This depends largely on its convenience of Machines.
manipulation, involving a study of levers, handles,
wheels, knobs and other auxiliary devices, their shape and place with
reference to the best adaptation to the average human frame, the ease and
extent of their motions, and the rapidity with which these motions may be
accomplished. The position of the operator, his natural tendencies, the
motions he will go through, all have to be imagined in view of the
attainment of his maximum convenience. This study, in the absence of any
counterpart of the proposed machine, often forces a resort to rough models,
or in lieu of this, a full-size blackboard sketch, extending to the floor, upon
which the location of parts may be tried for convenience.”
In the National Museum, at Washington, the visitor as he
Resources Rich or
inspects examples of American aboriginal art is Meagre as
astonished at its union of utility and beauty. Boat and Affecting
Invention.
paddle, spear and hook, basket and vase, are as
admirable in form as useful in traveling, fishing, or
carrying corn or water. How far an aboriginal designer may go largely turns
upon what variety of resources Nature offers him. No few score families on
a lonely islet of the Pacific can possibly rival the cloths and carvings
displayed by tribes ranging a Pennsylvania, or a California, abounding with
diverse minerals, plants and animals. When skill and invention occupy so
rich a land they flower into the highest creations of aboriginal art. And yet it
may be that the very fewness of a designer’s resources but spurs him to all
the more ingenuity. It depends upon who the man is. As we look upon a
collection of Eskimo harpoons and knives, coats and kayaks, we marvel that
all these should be produced with so much excellence and variety from a
scanty store of bones and teeth, sinews and hides, with but little iron or
none at all.[10]

[10] Two unrivalled books on aboriginal invention have been written by Mr. Otis T. Mason,
Curator of the Department of Ethnology at the National Museum,
Washington:—“Woman’s Share in Primitive Culture,” New York, D. Appleton & Co.,
1894; and “The Origin of Inventions,” London, Walter Scott Publishing Co., and New
York, C. Scribner’s Sons, 1905. Both volumes are fully illustrated.
The annual reports of the Bureau of Ethnology, Smithsonian Institution, Washington,
describe and illustrate American aboriginal art so fully and admirably as to be
indispensable to the student.

CHAPTER IX
FORM—Continued. FORM IN ABORIGINAL ART, AS AFFECTED BY
MATERIALS. OLD FORMS PERSIST IN NEW MATERIALS

Nature’s gifts first used as given, then modified and copied . . . Rigid materials mean stiff patterns . . .
New materials have not yet had their full effect on modern design.

o multiplied are the resources of modern industry that Aboriginal Art.
S desired forms are created at will, almost without regard
to the material employed. It is not so in primitive art,
to which for a brief space we will now turn so that our survey of form,
though all too cursory, may be refreshed by a contrast of old with new. Let
us begin with a glance at some of the aids with which man first provided
himself, taking the gifts of nature just as they were offered. In large areas of
the Southern States, and of Central America, the gourd for ages has been a
common plant, and has long served many Indian tribes as a water pitcher.
On sea-shores, where the gourd did not grow, conch-shells were used
instead, their users breaking away the outer spines and the inner whorls,
leaving within a space clean and clear. Both gourds and shells gave their
forms to the clay vessels which succeeded them.

Gourd-shaped vessel from Arkansas.
“Pottery of the Ancient Pueblos.”
W. H. Holmes.

Gourd and derived forms. “Pottery of the Ancient Pueblos.”
W. H. Holmes.

Pomo basket. National Museum, Washington.

In Zuni land, says Mr. F. H. Cushing, the first vessels for water were
sections of cane or tubes of wood. We may infer that the wooden tubes were
copied from the cane stems. What at first was passively accepted as nature
gave it, was afterward changed a little, and then was step by step changed
much, so that at length there grew up processes of manufacture. There was,
for example, in California a wealth of osiers, reeds, and roots well suited for
making baskets; these at last were perfected as water-tight receptacles
neither brittle like a shell nor liable to a gourd’s swift decay. Beginning
probably in mere wattling, in the rude plaiting of mats and roofs, the weaver
came gradually upon finer and stronger materials than at first, with equal
pace rising to new delicacy of finish and beauty of design. At the National
Museum in Washington, the Hudson collection of Indian baskets from
California includes the finest specimen in the world, a Pomo basket. Its
sixty stitches to the running inch were possible only through using the carex
root, easily divided into threads at once slender and strong.[11]
[11] Many of the handsomest baskets at the National Museum, as well as baskets from
other great collections, are illustrated, partly in color, in “Indian Basketry,” by Otis T.
Mason, curator of the ethnological department of the National Museum. The publishers are
Doubleday, Page & Co., New York.

Bilhoola basket of woven cedar bast. “Basket work of North American Aborigines.” Otis T.
Mason.

It is interesting to observe the limitation imposed upon a primitive designer
by the qualities of the leaf, shell, or cane in his hands, the way in which
these qualities point him to the forms in which he may excel. Of this we
have capital examples in the basket-work of the North American aborigines
as described by Mr. Otis T. Mason, in the report of the Smithsonian
Institution, 1883-84. He says: “Along the coast of British Columbia the
great cedar (Thuja gigantea) grows in the greatest abundance, and its bast
furnishes a textile material of the greatest value. Here in the use of this
pliable material the savages seem for the first time to have thought of
checker-weaving. Mats, wallets, and rectangular baskets are produced by
the plainest crossing of alternate strands varying in width from a millimeter
to an inch. Ornamentation is effected both by introducing different-colored
strands and by varying the width of the warp or the woof threads. . . . It is
not astonishing that a material so easily worked should have found its way
so extensively in the industries of this stock of Indians. Neither should we
wonder that the checker pattern in weaving should first appear on the west
coast among the only peoples possessing a material adapted to this form of
ornamentation.”

A square inch of the Bilhoola basket.

Referring to the water-bottles of the Pai Utes, Mr. Mason says: “This style
can be made coarse or fine, according to the material and size of the coil
and outer threads. If two twigs of uniform thickness are carried around, the
stitch will be hatchy and open; but if one of the twigs is larger than the
other, or if yucca or other fibre replace one of them and narrower sewing
material be used, the texture will be much finer.” Baskets and rain-hats, as
woven by Haidas and many other tribes, are waterproof when wet, owing to
the closeness of their texture.

A free-hand scroll. The same developed in a woven fabric.
“Form and Ornament in Ceramic Art.” W. H. Holmes.

When reeds or somewhat rigid fibres are woven, they
Idiom of Material.
compel a straightness of edge in patterns and designs. A
wave has to be suggested by stepped or broken lines, and
so we have a rectilinear meander or fret, in contrast with its free-hand form

as developed in a woven fabric. Under the constraint of her material a
squaw as she weaves a design into a basket, must give squareness to a
contour which would be somewhat rounded were it executed in delicate
threads. This is clear in the human figures of the Pomo basket shown on
page 109; and in those of a Yokut basket bowl, also in the National Museum
in Washington, illustrated on the next page.

Yokut basket bowl.
“Basket Work of North American Aborigines.” Otis T. Mason.

Stone and brick-work, in their rectilinear shapes, impose a rigidity in
architectural design from which modern bricks, in their rich variety of flat
and curved surfaces, have wrought emancipation. In the new residential
streets of St. Louis, for example, the architecture owes much of its freedom
and beauty to the new shapes in which brick is now manufactured. Even
wider liberty than now falls to the lot of the brick-maker has always been
enjoyed by the potter. In his hands clay lends itself to any desired imitation,
to any fresh design however fanciful; what is more it invites those
modifications of old forms in which art takes its chief forward strides. All

but infinite are the variations which Japanese potters have played on the
shapes of vases, jars, kettles, and basins, each clearly true to its type, while
at the same time original in a pleasing way. How the Japanese artist in clay
has rejoiced in his freedom is exemplified in the collection of Japanese
pottery at the Museum of Fine Arts, in Boston. Says Mr. Edward S. Morse,
who brought this collection together: “Utensils for every day life, terra cotta
funeral urns, large terra cotta bowls, weights for fishing nets, brush handles,
and even clothes-hooks are in Japan made of pottery. Where we use silver
and other metals, or glass, in making articles for daily use, the Japanese use
pottery.” He adds: “The prehistoric pottery of Japan was modeled by hand,
and to-day in various parts of the empire, this ancient art is continued in its
prehistoric form. There are many potters in Japan who are still at work
using only the hand in making bowls, delicate tea-pots, and dishes of
various kinds. The pottery vessels offered at Shinto shrines are usually
made without the use of the wheel and are unglazed. The potter’s wheel was
brought to Japan from Korea. The first was probably the kick-wheel used in
Satsuma and other southern provinces.”
The Japanese employ not only clay but wood in methods that richly repay
study. Says Mr. Ralph Adams Cram:—“In one respect Japanese architecture
is unique: it is a style developed from the exigencies of wooden
construction, and here it stands alone as the most perfect mode in wood the
world has known. As such it must be judged, and not from the narrow
canons of the West that presuppose masonry as the only building material.
. . . Perhaps the greatest lesson one learns in Japan is that of the beauty of
natural wood, and the right method of treating it. The universal custom of
the West has been to look on wood as a convenient medium for the
obtaining of ornamental form through carving and joinery, the quality of the
material itself being seldom considered. In Japan the reverse is the case. In
domestic work a Japanese builder shrinks from anything that would draw
attention from the beauty of his varied woods. He treats them as we do
precious marbles, and one is forced to confess that under his hand wood is
found to be quite as wonderful a material as our expensive and hardly
worked marbles. In Japan one comes to the final conclusion that stains,
paints, and varnish, so far as interior work is concerned, are nothing short of
artistic crimes.”[12]

[12] “Impressions of Japanese Architecture and the Allied Arts,” by Ralph Adams Cram.
New York, Baker & Taylor Co., 1905.

In strong contrast with the art of Japan is that of Egypt; on the banks of the
Nile the first buildings were of limestone, succeeded by huge structures
reared from Syene granite, with no little loss in delicacy of ornamentation.
It was only when marble, all but plastic under the chisel, was adopted by
the Greek sculptor, that the frieze of the Parthenon could spring into life.
Here William Morris should be heard. In “Hopes and Fears for Art,” he
says: “All material offers certain difficulties to be overcome and certain
facilities to be made the most of. Up to a certain point you must be master
of your material, but you must never be so much the master as to turn it
surly, so to say. You must not make it your slave, or presently you will be its
slave also. You must master it so far as to make it express a meaning, and to
serve your aim at beauty. You may go beyond that necessary point for your
own pleasure and amusement, and still be in the right way; but if you go on
after that merely to make people stare at your dexterity in dealing with a
difficult thing, you have forgotten art along with the rights of your material,
and you will make not a work of art, but a mere toy; you are no longer an
artist, but a juggler. The history of art gives us abundant examples and
warning in this matter. First clear, steady principle, then playing with the
danger, and lastly falling into the snare, mark with the utmost distinctness
the times of the health, the decline, and the last sickness of art.” He
illustrates this in detail from the history of mosaic in architecture.
While the modern artist duly respects the idiom of his new materials, their
diversity and refinement, in granting him the utmost freedom, enable him to
attain a truth of execution unknown before to-day. For writing on papyrus a
brush had to be used; on vellum or paper, a pen or pencil may also be
employed, tracing lines no wider than a hair. Our grandmothers were fond
of sewing on a perforated card a motto or a flower in silk thread; such a
sampler always had an unpleasant straightness in its outlines. When in
weaving silk or linen there may be two hundred threads to the running inch
instead of ten, the designer can introduce curves almost as flowing as if he
were a painter. So too in architecture: the log hut was perforce straight in its
every line; stone and brick made possible the arch; iron and steel are
bringing in a free choice of the best lines, whether straight or curved, all

with a new sprightliness, as witness the best of our office-buildings in New
York, such as the Whitehall, Trinity, and Empire Buildings.

Sampler on cardboard, executed in silk thread.

Bark vessel, and derived form in clay.
“Form and Ornament in Ceramic Art.” W. H. Holmes.

Art in its early stages seldom displays any outright
Old Forms
invention; with all the force of habit the savage artist Repeated in New
clings to old familiar shapes, and it is interesting to Materials.
remark how dealing with a new material may lead or
even oblige him to modify a traditional form. The Algonquins inhabit a
country in which the birch is common. They cut and fold its bark into
vessels which, when imitated in pottery, have an unusual rectangularity. In

many Indian tribes it was customary to use as a water-holder the paunch of
a deer or a buffalo; many ancient urns of Central America have an aperture
at an upper extremity, copied from the paunch, in every case with a
simplification of outline. Winged troughs of wood were undoubtedly in the
mind of the man who made the earthen vessel illustrated on the next page,
found in an ancient grave in Arkansas. As usual the borrower put something
of himself into his work, reminding us that the law of evolution is descent
with modification. An earthen vessel, illustrated on the next page, was
plainly copied from a shell vessel such as the specimen found not far off, in
Indiana. When the Clallam Indians, of the State of Washington, began to
weave baskets, they imitated the forms of their rude wicker fish-traps. The
like persistence was shown by the Haida squaws when taught by the
missionaries to make mats from rags; they repeated their ancient twined
model, long employed for mats and hats of vegetable fibres. As in America,
so also in Europe; when the makers of celts passed from stone to copper or
bronze, they reproduced the old forms, and only gradually learned to
economize metal, so much stronger than stone, and so much harder to get,
by narrowing and flattening their new weapons and tools.

Vase from tumulus. St. George, Utah.
“Pottery of the Ancient Pueblos.” W. H. Holmes.

“Form and Ornament in Ceramic Art.” W. H. Holmes.

Fro
m
W.
H.
Hol
Wooden tray. me Clay derivative.
s’

Shell vessel made from a Busycon Earthen vessel, imitation of shell,
perversum, found at Ritchersville, Missouri.
Indiana.
“Art in Shell of the Ancient Americans.”

Electric lamps in candle shapes.

Modern manufacture in its designs gives us a kindred persistence of old
forms in new things. For electric illumination we have bulbs which recall
the shape of a candle-blaze, or surmount an old-fashioned candlestick; a
gas-burner, popular for fifty years, repeats in milky porcelain the whole
length of a candle. Gas-grates, in uncounted thousands throughout our cities

every winter, offer us flames which flicker and leap over asbestos and clay
molded into the semblance of maple or charcoal. Nor is the engineer
himself, for all his sternness of discipline, quite free from prolonging the
reign of the past, even at unwarrantable cost. When steel was first used for
steam boilers there was a period of hesitation during which the metal was
used unduly thick, as if to maintain the long familiar massiveness of iron
structures. When automobiles were invented, they at first closely resembled
common carriages. To-day, designers have departed from tradition, and
provide us with horseless vehicles which respond to their new needs in
ways wholly untrammeled by inherited ideas. In an automobile, driven by
steam or gasoline, there must be due disposition of fuel, of machinery, of
cooling apparatus, all so combined as to bring the center of gravity as low
as may be best, affording ready access to any part needing lubrication,
repair, or renewal; throughout there must be the minimum of dead weight,
of friction, and of liability to derangement; all with means of easy, quick,
and certain control. Why should these requirements be deferred to repeating
the model of a carriage drawn by a horse? In Europe, to this hour, the
railroad carriages are an imitation of the old road-coaches, horse carriages
slightly modified. America, fortunately, from the first has had cars directly
adapted to railroad exigencies, with a thoroughfare extending the whole
length of a train, avoiding the box-like compartments which may give the
lunatic or the murderer an opportunity to work his will.

Notre Dame de Bonsecours, Montreal. Before restoration.

NEW AMSTERDAM THEATRE, NEW YORK.
No pillars obstruct a full view of the stage.

Sometimes an inherited form taken to a new home proves to be faulty there,
and is discarded. When Normandy sent forth its children to Canada, they
built on the shores of the St. Lawrence just such high-pitched roofs as had
sheltered them in Caen and Rouen. An example remains at Montreal in the
roof of Notre Dame de Bonsecours. But in Montreal and Quebec the
snowfall is much heavier than in Northern France, and the Norman roofs at
intervals from December to March were wont to let loose their avalanches
with an effect at times deadly. To-day, therefore, in French Canada many of
the roofs, especially in towns and cities, are flat or nearly flat, while the best
models quite reverse the old design. In breadths somewhat concave they
catch the snow as in a basin, and allow it to melt slowly so as to run down a
pipe through the center of the building.
Under our eyes, day by day, iron and steel are taking the place of stone and
wood in architecture and engineering; yet the force of habit leads us to

continue in metal many troublesome details which were imperative in the
weak building materials of generations past. It was as recently as the
autumn of 1903 that the first large American theater was opened having no
columns to obstruct views of its stage. The architects of the New
Amsterdam Theater, New York, simply by availing themselves of the
strength of steel cantilevers have shown that henceforth all large
auditoriums may be free from obstructions to a view of the stage, pulpit or
platform. See facing page 118.
Modern architecture, in the judgment of an eminent critic, has not yet fully
responded to its new materials and methods. Says Mr. Russell Sturgis, of
New York, in “How to Judge Architecture”:—“Every important change in
building, in the past, has been accomplished by a change in the method of
design, so that even in the times of avowed revival there was seen no
attempt to stick to the old way of designing while the new method of
construction was adopted; now in the nineteenth century, and in what we
have seen of the twentieth century, our great new systems of building have
flourished and developed themselves without effect as yet upon our
methods of design. We still put a simulacrum of a stone wall with stone
window casings and pediments and cornices and great springing arches
outside of thin, light, scientifically combined, carefully calculated metal—
the appearance of a solid tower supported by a reality of slender props and
bars.”

CHAPTER X
SIZE

Heavenly bodies large and small . . . The earth as sculptured a little at a time . . . The farmer as a
divider . . . Dust and its dangers . . . Models may mislead . . . Big structures economical . . .
Smallness of atoms . . . Advantages thereof . . . A comet may be more repelled by the sun’s light than
attracted by his mass.

uildings, carriages, structures of all kinds, whether reared by art or
B nature, often resemble one another in form while varying much in
size. Differences of dimensions are of importance to the inventor and
discoverer, and will be here briefly considered, beginning with a few of
their obvious and elementary aspects.

Cinders large and small on hearth.

A cube as subdivided into 8 cubes of 4 times more
surface.

One frosty evening I sat with three young pupils in a Cinders Big and
room warmed by a grate-fire. Shaking out some small Little.
live coals, I bade the boys observe which of them turned
black soonest. They were quick to see that the smallest did, but they were
unable to tell why, until I broke a large glowing coal into a score of
fragments, which almost at once turned black. Then one of them cried,
“Why, smashing that coal gave it more surface!” This young scholar was
studying the elements of astronomy that year, so I had him give us some
account of how the planets differ from one another in size, how the moon
compares with the earth in volume, and how vastly larger than any of its

worlds is the sun. Explaining to him the fiery origin of the solar system, I
shall not soon forget his delight—in which the others presently shared—
when it burst upon him that because the moon is much smaller than the
earth it must be much cooler; that indeed, it is like a small cinder compared
with a large one. It was easy to advance from this to understanding why
Jupiter, with eleven times the diameter of the earth, still glows faintly in the
sky by its own light, and then to comprehending that the sun pours out its
wealth of heat and light because the immensity of its bulk means a
comparatively small surface to radiate from.

Cube built of 27 cubes of 9 times more
surface.

To make the law concerned in these examples definite and clear, I took
eight blocks, each an inch cube, and had the boys tell me how much surface
each had—six square inches. Building the eight blocks into one cube, they
then counted the square inches of its surface—twenty-four: four times as
many as those of each separate cube. With twenty-seven blocks built into a
cube, that structure was found to have a surface of fifty-four square inches
—nine times that of each component block. As the blocks underwent the
building process, a portion of their surfaces came into contact, and thus
hidden could not count in the outer surfaces of the large cubes. The outer
surfaces of these large cubes I then painted white; when each was separated
into its eight or twenty-seven blocks, we saw in unpainted wood how

surfaces were increased by this separation into the original small cubes.
Observation and comparison brought the boys to the rule involved in these
simple experiments. They wrote: Solids of the same form vary in surface as
the square, and in contents as the cube, of their like dimensions.
This elementary law I traced that year in a variety of illustrations presented
in “A Class in Geometry,” published by A. S. Barnes & Co., New York. Our
excursions, since extended, are here given as an example of the knitting
value of a pervasive rule kept constantly in mind.
Our planet in diverse ways illustrates the law, just stated,
Earth Sculpture.
of surfaces and volumes. Forces of unresting activity
quietly transform the hills and plains, the sea coasts and
lake shores of the world, and so gradually that in many cases detection
proceeds only by noting the changes wrought in a century. For the most part
these forces break up large masses into fragments, or slowly wear away the
surfaces of rocks into dust. A lichen takes root on a granite ledge, and in a
few years reduces the rock to powder. Rain always contains a little acid, so
that in time flint itself is consumed, for all its hardness. Water soaking
through soils to form underground streams has hollowed out vast caves, as
notably in Virginia and Kentucky. Limestones and sandstones are of open
texture, and take up much moisture into their pores; in cold weather this
freezes, and in expansion wedges off thin flakes of stone. In the North one
sees the ground strewn with such splinters when the warm April sun has
melted the snow from beside a limestone fence. Watch the rills as they
descend a hillside during a rainstorm and just afterward. They are dark with
mud, and on steep declivities they carry down pebbles and bits of broken
stone, building up valleys at the expense of high ground. Fed on a huge
scale by such mud, the Mississippi River bears in suspension to the Gulf of
Mexico a little more than a pound of solid matter in every cubic yard, a
prime example of how the waters of the globe gain upon the land. The Falls
of Niagara have retreated several miles from their original plunge; the
carving of their channel has been wrought much less by the rushing waters
than by their burden of abrading earth and sand. The ceaseless churning of
water at the foot of the Falls cuts back into the rock, undermining its upper
layers, so that ever and anon they break off from the brink of the cataract,
with the effect that the stream steadily retires.

Throughout the ocean are strong currents to be constantly surveyed and
charted on the mariner’s behalf. These currents transport fine mud, and
organisms living and dead. Corals flourish best where such currents fetch an
abundant supply of food, just as plants thrive best in rich, loose soil. Life in
the sea just like life on land is thus dependent on forces which divide large
masses into small, and distribute these small masses over wide areas,
chiefly by water carriage.
Inventors have taken a hint from nature as she carries a Breaking Earth
burden of mud and pebbles in a rapid stream of water. A for Removal or
modern method of deepening a water course is to reduce Tilth.
to fine silt the surface of its bed, and then remove this silt
with a powerful stream. Water in swift eddies both lifts and bears away not
only clay, but stone and gravel when these are small enough. In placer-
mining streams of water much more powerful are directed against hill-
slopes of earth and stone, which disappear a great deal faster than by means
of spades and shovels. One of our Northwestern railroads runs for some
miles along the base of a steep ridge, from which at times heavy rains wash
down masses of earth, sand and gravel to the track. A powerful steam pump
forcing a stream through hose removes the obstructions from the line with
amazing rapidity. Work a good deal commoner and vastly more important
consists in taking a process begun by nature and carrying it many steps
further, so as to break up masses of earth again and again. The plow, the
harrow, the sharp-toothed cultivator, divide and subdivide the soil of farm
and garden so as to offer rootlets new surfaces at which rain may be drunk
in with its nourishing food. When a garden patch is to be fertilized by
bones, these serve best when reduced to meal, so as to be quickly and
widely absorbed.
In earth-sculpture one of the busiest agents is the wind, Work of the
especially as it seizes ocean waves and dashes them upon Winds.
beach and cliff, grinding large stones to pieces, and
reducing these at last to mere pebbles and sand. On land the gales take hold
of sand and dust with effects even more telling: sand flung against the
hardest quartz or granite will bring it to powder at last. Sand dunes, shifting
under the stress of high winds, have spread desolation around
Provincetown, Massachusetts, and in many another region once fertile
enough. This process of nature immemorially old has been copied in

modern invention, by the sandblast devised by the late General Tilghman of
Philadelphia. In its simplest form, sand from a hopper falls in a narrow
stream upon window panes, glassware and the like, to be roughened except
where protected by a paper pattern. Had sandstone in lumps, as large as
playing marbles, been dropped on the glass, there would have been harmful
fracture; as each particle of sand weighs too little in proportion to its
striking surface to do more than detach a tiny chip, we have a bombardment
wholly useful.
Primitive man achieved an incomparable triumph when Dimensions in
first he kindled fire by swiftly twirling one dry stick Ignition.
upon another, dropping the tiny sparks on finely divided
tinder, quick to catch fire because it presented much surface to the air. Peat,
a fuel common in many parts of the world, easily dug from bogs and
marshes, can be readily dried if chopped into fragments and exposed to the
wind in open sheds. Charcoal easily produced from wood of any kind, is
often used to absorb harmful gases in boxes of preserved meats and in
household refrigerators. Its effectiveness is due to its minute pores,
presenting as they do a vast area of capillary attraction. Charcoal, of course,
burns faster when powdered than when unbroken; and gunpowder, into
which charcoal largely enters, is molded into cakes either big, if it is to burn
somewhat slowly, or is pressed into fine grains, when an explosion all but
instantaneous is desired.
Common dust surrounds us always, entering the tiniest Dust Common
chink of wall and ceiling to show its path by a defacing and Uncommon.
mark. In dry seasons it abounds to a distressing degree,
and accumulates rapidly at considerable heights from the ground. Observe a
roof of the kind that slopes gradually toward the street, with a trough
running along the cornice to carry off the rain or melted snow. When such a
gutter is undisturbed for a few months it is clogged with mud due to the
dust which has been lifted by winds to the roof, and swept by successive
showers into the gutter. Dust particles, because they have so much surface
for their mass, are readily caught up and borne to heights far exceeding
those of the highest roofs. The terrific explosion of the volcano at Krakatoa,
in the Sunda Strait of Java in 1883, shot more than four cubic miles of dust
into the upper levels of the atmosphere, encircling the globe with particles

which fell so slowly as for months to color the sunsets of New York and
Canada, ten thousand miles away.
Wheat like other grain is combustible, hence as food it Inflammable Dust.
sustains bodily warmth. Under stress of necessity wheat,
corn, and barley have been burned as fuel when coal and
wood have been lacking. In the process of flour-making wheat is ground to
a powder so fine that when its particles are diffused through the air of a
mill, there is a liability to explosion because the inflammable dust comes so
near to contact with the atmospheric oxygen that at any moment they may
unite. At Minneapolis, frightful disasters were brought about in this way
until specially devised machines removed the dust. In coal mines, too, coal
may fill the air with a dust so fine that explosions take place, with serious
loss of life. In Austria it has been found that the fineness of the dust has
more to do with the violence of such explosions than has the chemical
composition of the particles.
In mining, let us observe, the whole round of work consists in separations
which bring masses from bigness to smallness, again and again. First of all
the solid walls and floors are broken up by pick, or drill, or powder, or all
together. Iron ores as hoisted to the surface of the earth are taken to breakers
which crush them into pieces suitable for the blast furnace. When the ores
carry gold, copper, lead, or tin, this crushing is followed by stamping to
facilitate the final process by which metal is separated from worthless rock.
Spinning and weaving, remote as they are from mining, Dimensions in
are equally subject to the law of surfaces and volumes. It Woven Fabrics.
is in furthering adhesion by giving their thread a
multiplied surface that the spinner and weaver manufacture cloth at once
strong and durable. The best linens and silks are spun in exceedingly fine
threads; canvases and tweeds have threads comparatively coarse. From the
cut edge of a piece of fine silk fabric it is hard to pull out a lengthwise
thread; the task is easy with sailcloth.
From observation let us turn to experiment as we further The Dimensions of
consider the law of size. Inventors, especially young Models.
inventors, are apt to underrate the difficulty of supplying
an old want in a new and successful way. In their enthusiasm they may lose

sight of principles which oppose their designs, as for instance, the rules
which govern the plain facts of dimensions. Mr. James B. Eads, in planning
his great bridge at St. Louis, chose three spans instead of one span. Why?
For the simple reason that if built in one span the weight of the bridge
would have been twenty-seven times that of a span one-third as long, while
only nine times as strong, assuming that both structures had the same form.
Two pieces of rubber will clearly exhibit the contrast in question. One piece
is three feet long, one inch wide, one inch thick; the other piece is one foot
long, and measures in width and thickness one-third of an inch. Placing
each on supports at its ends we see how much more the longer strip sags
than the shorter. The longer has twenty-seven times the mass of the other,
but only nine times its strength. Many an inventor has ignored this
elementary fact and built a model of a bridge, or roof, which has seemed
excellent in the dimensions of a model, only to prove weak and worthless
when executed in full working size.

The upper strip of rubber is thrice as long, wide and deep as the lower, which sags less.

We have glanced at a few cases of invention where it has
Why Big Ships are
been remembered that the larger a mass of given shape Best.
the less its surface as compared with its bulk. Let us note
how this rule enters into the tasks of the shipbuilder. We take a narrow vial
of clear glass, nearly fill it with white oil or glycerine, cork it, and shake it
smartly. Holding the vial upright we observe that the largest bubbles of
imprisoned air come first to the top of the liquid, because in comparison
with bulk they have least surface to be resisted as they rise. For a parallel
case we visit the docks of New York, and note a wide diversity of steamers.
Here is the “Baltic,” of the White Star Line, with a length of 726 feet, and a
displacement of 28,000 tons. Less than a mile away is a small steamer
trading to Nova Scotia, having a length of but 260 feet, and a displacement

of only 1,000 tons or so. We recognize at once why the quickest ships are
always among the biggest. It is simply the case of bubbles small and great
over again; the biggest vessels in proportion to size have least surface
whereat to resist air and sea, so that they can run fastest between port and
port. As with ships, so with their engines; economy rests with bigness; the
largest engines have proportionately least surface at which to lose heat by
radiation or by contact, or for resistance by friction as they move. Indeed in
designing ocean steamers of the greyhound type it is imperative that the
utmost possible dimensions be adopted. The “Mauretania” and the
“Lusitania” just built for the Cunard Company, to be driven by steam
turbines at 25 knots an hour, will each demand 70,000 horse-power. They
are 790 feet in length over all, 88 feet in beam, 601⁄2 feet in depth, with a
displacement of 45,000 tons. Mr. William F. Durand, in his work on the
resistance and propulsion of ships, considers three vessels less huge and
swift than these Cunarders and able to cross the Atlantic in say seven days.
The 5,000-ton ship could barely make the trip with no cargo at all, a
16,000-ton ship would be able to carry 3,000 tons of freight, while a
20,000-ton ship could carry 4,200 tons of cargo. Burdens of hull,
machinery, and coal do not increase as rapidly as gross tonnage when the
dimensions of a ship are enlarged.

Air bubbles rising in oil.

Now we begin to realize how great is the boon of cheap Bigness Needs
steel, much stronger than iron, of which ships and Strong Materials.
engines may be built bigger than at any earlier period.
Steel of great strength has made feasible, too, the Eiffel Tower in Paris,
nearly a thousand feet tall, the office-buildings of New York thirty stories in
height, and steel will soon cross the St. Lawrence near Quebec with a single
span of 1,800 feet. In 1904, at Schenectady, N. Y., the New York Central &
Hudson River Railroad Company began comparisons between an electric
locomotive of 201,000 pounds, shown opposite page 476, and a steam
locomotive so huge that with its tender it weighed no less than 342,000
pounds. Steel, as the material of engines and tools of all sorts enables us to
build in dimensions bolder than ever before; or, if old dimensions are not
surpassed, we are free to employ velocities quite out of the question with
iron.

It is a long time since adventurers first entrusted themselves to floating logs,
afterward tied together as rafts, and slowly improved until they became
boats moved by paddles or oars. Thus far little else than failure has attended
the inventors who have sought to navigate the air as easily as river, lake or
sea. A stride toward success was however distinctly taken when the
strongest known alloys, those of steel and nickel, gave the aeronaut a
stronger boiler, pound for pound, than he ever had before, with wings
lighter in proportion to their power than those of earlier experiments. Let
the burden of his apparatus be further reduced, and by one-half; then we
may expect him to reign in the air as securely as the sea-gull. The original
resource of the aeronaut, his balloon, suffers from a permanent disability.
Air has but 1⁄770 the specific gravity of water, so that a balloon must be
enormous to have any carrying capacity worth while. And what would
become of a balloon, its rudder and ropes, if caught in a hurricane of eighty
miles an hour?
Let the aeronaut continue his wistful and envious gaze at A Store Continues
the birds in the sky while we turn our attention to mother the Lesson.
earth, there to note how every day trade surrounds us
with further illustrations of the law of size, of the gains which may attend
bigness. We enter a department store, displaying a varied stock of foods,
clothing, shoes, furniture, and so on. As we cast our eyes about its counters,
shelves, and floor we see cans of vegetables, fruit, and fish; jars of olives
and vinegar; boxes of rice, soap and crackers; paper sacks of flour and
meal. Outside the door are piled kegs, barrels, and packing cases. Plainly
the cost of paper, glass, tin, and lumber for packages must levy a large tax
on retailing. Once more is recalled our old lesson with the inch-cubes; the
bigger a jar, box, or sack, the less material it needs in proportion to its
capacity. Wholesale packers of merchandise save money as they form
packages of the largest size. The contents of each box, crate, and sack tell
the familiar story once again. The coffee is ground from the bean that it
may be readily infused in the coffee-pot; wheat is reduced to flour, oats to
fine meal, that they may be quickly cooked; sugar is crushed that it may
rapidly dissolve in the tea cup. This very task began long ago with the
mastication of food by the teeth, diminishing the size of morsels while
moistening them for digestion before they reached the stomach.

During a visit to the country one summer, we observed Summer Holiday
new examples of our familiar rule. When we compared Notes.
the dimensions of a small sectional cabin with those of a
large house, we saw the principal reason why the cabin was hard to keep
cool in July, and hard to keep warm in December. We noticed tasks which
depended upon giving wood, cloth or other material as much surface as
possible, whether new forms were like old ones or not. A neighboring
sawmill was busy cutting up logs into thin boards; these were piled in open
tiers, so that the drying winds might speedily finish their work. In the same
way we noted a laundress spreading out by itself each table-cloth and apron
fully to catch the wind, instead of leaving the linen as a solid heap in her
basket, where only the edges would be dried. When the farm-hands went
haymaking they followed the same rule; they tedded out their gavels to give
them the utmost supply of sun and air; when all was as dry as a bone they
reared a haycock of compact form so as to expose the least possible surface
to rain and snow.
So much for things to be observed in a country ramble, Dimensions
in a city store, or at the docks of a busy port. Apart from Molecular.
all such things is a world unseen, standing beneath the
visible world, and equally worthy of study. Here knowledge is based upon
inferences, upon what lawyers call circumstantial evidence. The chemist by
means purely indirect studies the molecule and the atom, objects that far
elude his microscope. A molecule is a part of a compound so small that it
cannot be divided without becoming something simpler. Thus a sugar
molecule is made up of carbon, hydrogen, and oxygen atoms; were these
disjoined, the sugar, as such, would cease to be, just as a brick wall no
longer exists when its bricks and their several slices of mortar are parted
from one another as separate units. Small as molecules are they have not
escaped the measuring rod of the physicist. Some years ago Lord Kelvin
experimentally arrived at the estimate that the average molecule has a
diameter of 1⁄760,000,000 inch. Such molecules when compared with masses of
like form, and of a diameter of one inch; have 760,000,000 times as much
surface. In the transmission of motion, with adhesion in play, surfaces count
for much, as when a wheel in motion is brought into contact with a wheel at
rest. Here may be an explanation of why electricity is conducted through a
wire with a velocity far exceeding any speed we can mechanically impress

upon the metal, because the molecules concerned have incomparably more
surface than the wire as a mass.
By virtue, also, of its minuteness the molecule as a Reservoirs of
reservoir of energy can far excel a mass of visible Energy.
dimensions. Let us compare two rotating spheres, one of
them of seven times the radius of the other. We spin both at the same
peripheral rate, and gradually increase this speed: which will be the first to
break apart under centrifugal strain? The larger, and why? Because the
cohesion of a sphere is in proportion to the area of its great circle, which
varies as the square of its diameter, while centrifugal strain under swift
rotation varies as the cube of that diameter, or as the volume of the sphere.
From this it follows that we may safely spin our small sphere with a
circumferential velocity seven times that given the large sphere; therefore as
containers of energy small spheres are more effective than large, and this
inversely as their diameters. Spheres, or bodies of any other form, if
reduced in dimensions to 1⁄760,000,000th, would as reservoirs of energy gain
760,000,000-fold. Thus we open a door of explanation regarding the
stupendous contrast between chemical energy and mechanical work.
Chemical processes are exerted by molecules and atoms, mechanical work
takes place among masses comparatively enormous in bulk. It may require
a hundred blows from a ponderous steam hammer to raise the temperature
of an iron bar ten degrees; that bar melts in ten seconds when plunged into a
flame produced by a few ounces of hydrogen and oxygen gases.
Recent experiments by Professor Joseph J. Thomson point to the probability
that the atom of the chemist while a unit, is in part built of electrons each
but one-thousandth part the size of a hydrogen atom. An electron, by virtue
of its infinitesimal minuteness, becomes able to hold proportionately much
more energy than is possible to an atom moving as a whole. This brings us
to some comprehension of the astonishing powers of radium, an element
which maintains itself at a temperature 3° to 5° Centigrade higher than that
of its surroundings, probably through the collision within each atom of its
component parts.

Dvorak Sound-mill.

Water-waves as they strike a shore or the sides of a basin Repulsion by
exert a thrust, or a repelling action, which may easily be Sound and Light.
observed. That sound-waves act in similar fashion is
proved by a little sound-mill devised in 1883 by Professor V. Dvorak, of the
University of Agram in Austria. It consists of four vanes, each a small card
slightly curved, mounted on a spindle. In a sounding-box nearby is a
tuning-fork which may be struck through its stem F. A Helmholtz resonator
has its wide opening turned toward this box, its narrow opening toward the
mill. A stroke on the tuning-fork emits vibrations which send tiny jets of air
against the sails of the mill, which accordingly rotate at a pace
proportionate to the loudness of the sound.

A beam of light deflects dust.

Professor Ernest F. Nichols of Columbia University, New York, and
Professor Gordon F. Hull of Dartmouth College, in the Journal of
Astrophysics, Chicago, June, 1903, describe their apparatus for measuring
the radiation pressure of light, a phenomenon analogous to that studied by
Professor Dvorak in the field of sound. In the same number of that Journal
they detail an experiment to show light exerting a driving action on very
tenuous particles. They burned a puff ball of lycoperdon to charcoal
spherules of about one-sixth the specific gravity of water. These spherules,
with some fine emery sand, they placed in a glass tube shaped like an hour-
glass; this tube was then exhausted of its gases until a mere fraction
remained which could not be removed. With the sand and charcoal in its
upper half the tube was held upright, while a beam of light twenty to forty
times as strong as sunshine was thrown on the tube just below its neck. By

tapping the glass a stream of sand and charcoal descended; the sand fell
through the beam without deflection; the charcoal particles were driven
away from the stream as they fell through the light. Part of this effect was
due to the slight remnant of gas left in the tube which, warmed by the light,
produced a motion resembling that of a Crookes’ radiometer; the remainder
of the effect was caused by the drive or repulsion of the luminous beam. It
is argued that this repulsion by light is probably one of the causes why the
sun seems to drive away the tail of a comet, whose particles being
extremely minute have much surface and little bulk, so that they are more
repelled by the light of the sun than they are attracted by his mass. To
approach cometary conditions in an experiment it would be necessary to
intensify sunlight no less than 1,600-fold, because on the surface of the
earth its own gravitation is 1,600 times greater than that which is there
exerted by the sun.
The law that a given shape when enlarged increases A Law as a
much more rapidly in volume than in surface has, in our Binding Thread.
brief survey, bound together a wide diversity of facts in
astronomy, geology, geography, navigation, engineering, mechanics,
physics, and chemistry. A good many times I have brought it before young
folks as a means of linking together everyday observations and principles of
sweeping comprehensiveness. Boys and girls are apt to think that there is a
formidable barrier between science and common knowledge. No such
barrier exists. The sun, his planets and their moons; the forces which carve
mountains and valleys; the arts of shipbuilders, of designers of bridges,
office-buildings, and lighthouses; the plans of the inventors of machinery;
the rules discovered by investigators who pass from appearances to the
underlying reality of molecule and atom, are all within the sway of the
elementary law we have been studying. There is a gain in thus pursuing a
connecting thread of classification, conferring order as it does on what
might else be an assemblage of things collected at random. A law such as
that of size links into unity, and fastens in the memory a vast array of
observations and experiments which otherwise would have no associating
tie, no common illumination.

CHAPTER XI
PROPERTIES

Food nourishes . . . Weapons and tools are strong and lasting . . . Clothing adorns and protects . . .
Shelter must be durable . . . Properties modified by art . . . High utility of the bamboo . . . Basketry
finds much to use . . . Aluminium, how produced and utilized . . . Unwelcome qualities turned to
profit . . . Properties long worthless are now gainful . . . Properties may be created at need.

aterials are valued for their properties as well as their forms. We now
M pass to a rapid survey of properties as observed in gifts of nature, as
modified by art, as turned to account in many ingenious ways, as
studied by the investigators who would fain know in what particulars of
ultimate form, size and motion, properties may really consist.
We go to market with a few different coins: one of them is worth a hundred
times as much as another of about the same size, because gold is more
beautiful than nickel, does not tarnish, may be hammered into leaves of
extreme thinness, or unites with copper as an alloy which withstands
abrasion for years after it leaves the mint. When we build a house we wish
strength in its foundation and walls, so we pay a higher price for granite
than for limestone; and choose for joists, floors and rafters well seasoned
wood in preference to newly sawn lumber liable to warp and crack with
heat in summer, with cold in winter. So with raiment: silk is preferred to
cotton or wool because handsomer, stronger, more lasting. But food comes
before shelter, raiment or any other need of mankind, and qualities of
nourishment and palatability mark off nuts, fruits, grain and roots as
suitable for food. In this regard all living creatures exercise discrimination
under penalty of death.
A score of sparrows are flitting about a door-yard; strew a handful
Food.
of crumbs on the gravel before them; at once the birds begin
picking up the bread, leaving the gravel alone. They know crumbs,
good to eat, from stone, not good to eat. The earliest races of men,
immeasurably higher than birds in the scale of life, have eaten every herb,
root, grass, and fruit they could find. Experiment here was as wide as the
world, and bold enough in all conscience. In many cases new and delicious

foods, thoroughly wholesome, were discovered. At other times, as when the
juice of the poppy was swallowed, sleep was induced, with a hint for the
escape from pain in artificial slumber. In less happy cases the new food was
poisonous; yet even this quality was pressed into service. In Mendocino
County, California, to this day, the Indians throw soap root and turkey
mullein, both deadly, into the streams; the fish thus killed are eaten without
harm. These same Indians make acorns and buckeye horse chestnuts into
porridge and bread, pounding the seeds into a fine flour and washing out its
astringent part with water. These and other aborigines use for food and
industry many plants neglected by the white man, taking at times guidance
from the lower animals. One of the early explorers of South Africa, Le
Vaillant, says that the Hottentots and Bushmen would eat nothing that the
baboons had left alone. Following their example he would submit to a tame
baboon new plants for acceptance or rejection as food.
As with food so with other resources almost as vital.
Weapons and
Long ago the savage learned that hickory makes good Tools.
bows and arrows, that as a club it forms a stout and
lasting weapon. He discovered, too, that in these qualities soft woods are
inferior and the sumach altogether wanting. Thus, too, with the whole round
of stones from which as a warrior or a craftsman he fashioned knives,
chisels, arrowheads, axes; it was important that only tough and durable
kinds should be employed. No lump of dry clay ever yet served as a
hammer or an adze; happy were the tribes, such as those of ancient Britain,
who had at hand goodly beds of flint from which a few well directed blows
could furnish forth a whole armory of tools and weapons.
In the eating of foods simply as found, in the use of Properties
materials for clothing or building just as proffered by the Modified.
hand of nature, much was learned as to their qualities;
some were found good, others indifferent, still others bad. Then followed
the art of modifying these qualities, so as to bring, let us say, a fibre or a
thong from stiffness to pliability and so make it useful instead of almost
worthless. The progress of man from downright savagery may be fairly
reckoned by his advances in the power to change the qualities of foods,
raiment, materials for shelter, tools, and weapons. These arts of
modification go back very far. At first they may have consisted simply in
taking advantage of the effects of time. In the very childhood of mankind it

must have been noticed that fruit harsh and sour became mellow with
keeping, just as now we know that a Baldwin apple harvested in October
will be all the better for cellarage until Christmas, the ripening process
continuing long after the apple has left its bough. Grains and seeds when
newly gathered are usually soft and, at times, somewhat damp; exposed to
the sun and dry air for a few days they become hard and remain sound for
months or even years of careful storage. In warm weather among many
Indian tribes such food was almost the only kind that remained eatable; all
else went to swift decay, except in parched districts such as those of
Arizona, so that roots, fruits, the flesh of birds, beasts, and fish had to be
consumed speedily, a fact that goes far to account for the gluttony of the red
man. His stomach was at first his sole warehouse; that filled, any surplus
viands went to waste. In frosty weather this havoc ceased; as long as cold
lasted there was no loss in his larder. A few communities, as at Luray,
Virginia, or at Mammoth Cave, Kentucky, in their huge caverns had
storehouses which would preserve food all the months of the twelve. In
New Mexico and other arid regions the air is so dry that meat does not fall
into decay. How it was discovered that smoke had equal virtue we know
not. Probably the fact came out in observing the accidental exposure of a
haunch of venison as the reek from a camp-fire sank into its fibres. Salt,
too, was early ascertained to have great value in preserving food. Suppose a
side of buffalo, or horse, to have fallen accidentally into brine in a pool or
kettle, and stayed there long enough for saturation, its keeping sweet
afterward would give a hint seizable by an intelligent housewife.
Preservation by burial in silos began in times far remote, and was fully
described by Pliny in the first century of the Christian era.
The skin just taken from a sheep, the hide when removed Properties in
from an ox, are both as flexible as in life. But they soon Clothing.
stiffen so as to be uncomfortable when worn as garments.
Wetting the pelt is but a transient resource; satisfactory, because lasting, is
the effect of rubbing grease, fat, or oil into the texture of the hide. Peary in
Greenland found that pelts in small pieces, and bird-skins, were softened by
the Eskimo women chewing them for hours together.
Wetting was as notable an aid to handicraft of old as today. Boughs, roots,
withes, osiers, or the stems of fibrous plants, when thoroughly saturated
with water became so soft as to be easily worked, yielding strands, as in the

case of hemp, separated from worthless pulp. Hence the basketmaker, the
wattler, the builder, the potter, the weaver of rude nets and traps, long ago
learned to wet their materials to make them plastic. Take now the reverse
process of drying, which toughens wood, and the sinews used as primitive
thread. Leaves when dried become hard and brittle of texture, hence the
necessity that when woven and interlaced as roofs the work shall promptly
follow upon gathering the material. In plaiting coarse mats and sails may
have begun the textile art which to-day gives us the linens of Belfast, the
silks of Lyons and Milan.
A good and serviceable imitation of silk is due to a Cotton
simple and ingenious treatment of cotton. In 1845 John Strengthened and
Mercer, a Lancashire calico printer, one day filtered a Beautified.
solution of caustic soda through a piece of cotton cloth.
He noticed that the cloth, as it dried, was strangely altered; it had shrunk
considerably both in length and breadth, had become stronger, with an
increased attraction for dyes. This was the beginning of the mercerization
which to-day produces cotton fabrics almost as strong and handsome as if
silk. The cloth, preferably woven of long Sea Island staple, is immersed in a
solution of caustic soda, and afterward washed in dilute sulphuric acid and
in pure water. As it enters the caustic bath the cotton is pure cellulose, as it
leaves the bath the fabric is hydrated cellulose, with new and valuable
properties. The structural change in the fibre is decided. The original
filament of cotton is a flattened tube, the sides of which are close together,
leaving a central cavity which is enlarged at each edge of the surrounding
tube. It is opaque and the surface is not smooth. The fibre has also a slight
twist. The tube after treatment becomes rounded into cylindrical form; its
cavity is lessened and the walls of its tube thicken; the surface becomes
smooth and each fibre assumes a spiral form. Effects like these of
mercerization are produced in paper as well as in cotton cloth, yielding
vegetable parchment, a familiar covering for preserve jars and the like.
Some sandstones, such as are common in Ohio and
Properties in
Indiana, soft when hewn in the quarry, soon harden on Building
exposure to wind and weather; materials of this kind in Materials.
early times afforded shelter more lasting than tents of
boughs or hides. But the building art was to know a gift vastly more
important when an artificial mud was blended of clay and water, with a

steady improvement both in the strength and durability of the product. It
was a golden day in the history of man when first a clayey paste was patted
into a pot, a bowl, a kettle: then was laid the foundation of all that the
potter, the brick maker, the tile molder have since accomplished. Another
remarkable discovery, needing prolonged and faithful experiment, was
reached when pottery was found to keep its form better when broken
potsherds and bits of flint were mingled with its clay. A discovery of equal
moment was that of mortar, probably approached in the daubing of mud or
clay into chinks of stones, with the admixture first of one substance and
then another until the right one was found, and the binder and the bound
became of one and the same hardness. The Romans, a deliberate race, took
two years in making a batch of mortar; that bond to-day protrudes from
their walls as more resistant to the tooth of time than stone itself.
But if water did much to modify properties, flame did
Flame and
infinitely more. A block of blue limestone thrust into a Electricity as
fire was burned to whiteness, and became lime, which, Modifiers.
mixed with water, proved a biting compound of slippery
feel,—an alkali indeed. This same wonderful flame caused water wholly to
disappear from a heated kettle; or could dissipate almost the whole of an
ignited brand or lump of fat. By cooking a food, it gave a new relish to the
poorest dish, banished from such a root as tapioca its poison, and when a
yam was baked it remained eatable for a twelvemonth. Fire enabled man to
melt metals as if they were wax, to soften iron or copper which a deftly
swung hammer shaped as he willed. Here, too, opened the whole world of
chemistry, one of its first gifts the power to take an ore worthless when
unchanged, and gain from it a battle-axe, a knife, an arrowhead. Even in
this day of electricity it is fire which the engineer must evoke to create
acids, alkalis, sugars, alcohols, from substances as different from these as
iron is from iron ore.
Electricity as a modifier of properties in turn throws flame into eclipse.
Take an example: a strip of ferro-nickel is fast dissolving in an alkaline
bath; attach one end of the metal to the negative pole of a battery or a
dynamo, the other end to the positive pole; at once solution ceases and the
metal begins to pick out kindred particles from the bath, adding them to
itself. Electricity has completely reversed the wasting process; what was
eaten away is now growing, what was a compound is now shaken into its

elements, one of which rapidly increases in mass. Nothing in the empire of
heat is as striking as this process—familiar in renewing the energy of a
storage battery. Many a union or a parting impossible to fire is wrought
instantly by the electric wave.
When Mr. Edison devised his electric lamp, his first
The Bamboo Rich
successful filaments were fibres of bamboo; they glowed in Utilities.
more brilliantly than anything else he could find, they
were tenacious enough to withstand intense heat for weeks together. A
single gift of nature, such as the bamboo, may be so many-sided that its
applications greatly enrich human life. A task of interest would be to trace
the vast indebtedness of modern science and art to carbon, iron, or silver, in
their various forms. But the bamboo is cheaper and more abundant than any
of these, so that it will be worth while to glance at the many wants it has
satisfied, at the creations it has suggested to ingenuity. In Ceylon, India,
China, Japan, the Malay archipelago, it is the chief item of natural wealth,
the main resource for the principal arts of life. First of all it provides food.
More than one case is recorded where its abundant seeds have staved off the
horrors of famine; these seeds, too, are commonly fermented to produce a
drink resembling beer. Many species of bamboo have shoots which when
young and tender are a palatable and nourishing food. As a building
material it is strong, durable and easily divided. Its sizes are various enough
to provide a fishing-rod for a boy, or a column for a palace.
“To the Chinaman, as to the Japanese,” says Mr. Freeman-Mitford, in “The
Bamboo Garden,” “the bamboo is of supreme value; indeed it may be said
that there is not a necessity, a luxury, or a pleasure of his daily life to which
it does not minister. It furnishes the framework of his house and thatches
the roof over his head, while it supplies paper for his windows, awnings for
his sheds, and blinds for his verandah. His beds, tables, chairs, cupboards,
his thousand and one small articles of furniture are made of it. Shavings and
shreds of bamboo stuff his pillows and mattresses. The retail dealer’s
measure, the carpenter’s rule, the farmer’s waterwheel and irrigating pipes,
cages for birds, crickets, and other pets, vessels of all kinds, from the richly
lacquered flower-stands of the well-to-do gentleman down to the humblest
utensils of the very poor, all come from the same source. The boatman’s
raft, and the pole with which he punts it along; his ropes, his mat sails, and
the ribs to which they are fastened; the palanquin in which the stately

mandarin is borne to his office, the bride to her wedding, the coffin to the
grave; the cruel instruments of the executioner, the beauty’s fan and parasol,
the soldier’s spear, quiver, and arrows, the scribe’s pen, the student’s book,
the artist’s brush and the favorite study for his sketch; the musician’s flute,
the mouth-organ, plectrum, and a dozen various instruments of strange
shapes and still stranger sounds—in the making of all these the bamboo is a
first necessity. Plaiting and wickerwork of all kinds, from the coarsest
baskets and matting down to the delicate filigree which encases porcelain,
are all of bamboo fibre. The same material made into great hats like
inverted baskets protects the coolie from the sun, while the laborers in the
rice fields go about looking like animated haycocks in waterproof coats
made of the dried leaves of the bamboo sewn together.”
In North America the Indians have had no such resource
Materials for
as the bamboo, but with tireless sagacity they have laid Basketry.
under contribution either for food or for the arts every
gift of the soil. In seeking materials for basketry, for example, they have
surveyed the length and breadth of the continent, testing in every plant the
qualities of root, stem, bark, leaf, fruit, seed and gum, so far as these
promised the fibres or the dyes for a basket, a wallet, a carrier. With all the
instinct of scientific research they have sought materials strong, pliant,
lasting and easily divided lengthwise for refined fabrics. In his work on
“Indian Basketry” Mr. Otis T. Mason has a picture of a bam-shi-bu coiled
basket, having a foundation of three shoots of Hind’s willow, sewn in the
lighter portions with carefully prepared roots of kahum, a sedge; while its
ornamental designs are executed in roots of a bulrush, the tsuwish. Often a
basket, as in this case, is built of materials found miles apart, each requiring
patient and skilful treatment at the artist’s hands.
A few trees, the cedar in particular, lend themselves to the needs of the
basketmaker with a generous array of resources. Mats of large size made
from its inner bark are common among the Indians of the Northern Pacific
Coast. From the roots of the same tree hats are woven as well as vessels so
close in texture as to be watertight. When the roots are boiled so as to be
readily torn into fibres, these are formed into thread, either woven with
whale-sinews or with kelp-thread as warp. Among the handsomest of all
Indian baskets are those of the Pomo tribe, one of which is shown on page
109. The splints for their creamy groundwork are made from the rootstock

of the Carex barbarae, which are dug from the earth with clam shells and
sticks, a woman securing fifteen to twenty strands in a day. These she
places in water over night to keep them flexible, and to soften the scaly bark
which is afterward removed. To make a basket watertight the Indians of
Oregon weave the inner bark of their maple with the utmost closeness. In
other regions a simpler method is to apply as water-proofing the gum of the
piñon, the resins of pines, or mineral asphalt. Equal diligence and sagacity
mark the Indians as users of stone. The Shastas heat a stone of such quality
that in cooling it splits into flakes for weapons and tools. They place an
obsidian pebble on an anvil, and with an agate chisel divide it as they wish;
all three being chosen from a vast diversity of stones which must have been
tried and found, inferior.
From Indian handicrafts, developed by aboriginal skill, Aluminium and
patience and good taste to remarkable triumphs, let us Its Uses.
turn to an achievement of a modern chemist who, calling
electricity to his aid, bestowed a new metal upon industry, making possible
new economies in a wide sisterhood of arts. Aluminium was discovered in
1828 by Wohler, a German chemist, who noted its lightness, toughness, and
ductility. At the Centennial Exhibition at Philadelphia, in 1876, a surveyor’s
transit built of aluminium was shown, but the metal at that time was six-
fold the price of silver, so that the instrument for some years remained
uncopied. Of course, engineers and mechanics were much interested in a
metal only about one-third as heavy as brass or copper, of white lustre, and
with as much as five-eighths the electrical conductivity of copper. All that
hindered the extensive use of the metal was its high cost. If that cost could
be lowered, at once copper, and even silver, would face a rival. After many
unsuccessful because expensive processes for obtaining the metal had been
devised, a method was found at once simple and inexpensive.
This method of separating aluminium from its compounds was devised by
Charles M. Hall, while an undergraduate student at Oberlin College, Ohio.
His success turned on his knowledge of the properties of related metallic
compounds. He recognized the probable value of aluminium in the arts,
could it be produced in large quantity at low cost. He believed that
electrolysis would prove the most convenient, thorough and inexpensive
method; but there was at that time no process known by which it could be
applied to this element. His problem was to find a form of electrolyte rich in

aluminium which should be comparatively easy to separate into its
elements, and to discover a substance for the solvent which should prove a
satisfactory bath. This latter substance must, furthermore, be a good
conductor of electricity, must readily dissolve the proposed electrolyte, and
must have a higher resistance to electrolytic disruption than the electrolyte.
To discover the needed substances for electrolyte and solvent involved the
examination of all available compounds of aluminium, the study of the
various possible solvents for the compound selected, and the determination
of electric conductivities. By virtue of rare familiarity with the chemistry
and physics of the subject, with the properties of every substance
concerned, the search was, after a time, rewarded with complete success. It
was found that bauxite—the oxide of aluminium, alumina, in fact—is
dissolved by molten cryolite, the double silicate of aluminium and sodium,
and that the latter, while dissolving the bauxite freely and serving as an
ideal solvent, also itself breaks up under the action of the electric current at
a much higher voltage than alumina. So far as known, these are the only
substances in nature which stand to each other in such relation as to permit
the commercial production of the metal.
Aluminium as constructive material has disappointed some of its earlier
advocates. It is difficult to work, gumming the teeth of files and resisting
cutting and drilling tools by virtue of the very toughness which makes it
desirable for tubes, columns, and the like. Its excellences, however, are
manifold: the German army on investigation found that helmets of
aluminium, as light as felt, turned the glancing impact of a bullet. For
soldiers’ use it now forms not only helmets, but cooking vessels, cartridge
cases, buttons, sword and bayonet scabbards. It gives the photographer as
well as the surveyor instruments which unite strength with lightness. It has
furthermore the quality which has long given value to the lithographic stone
of Hohenlofen in Bavaria. Aluminium takes a sketch as perfectly as does
the stone, with the inestimable advantages that the metal may be readily
curved for a cylinder press, that it is compact and light in storage, while
without the brittleness which has made stone so costly a servant to both
artists and printers. To produce a deep color from stone it may be necessary
to print one impression over another again and again; from aluminium a
single impression is enough, as severe pressure may be safely applied.

Aluminium has so great an affinity for oxygen as to play a conspicuous part
in the metallurgy of other metals. In the casting of iron, steel or brass, the
addition to each ton of two to five pounds of aluminium greatly improves
the product; the aluminium by combining with the occluded gases reduces
the blowholes and renders the molten metal more fluid and therefore more
homogeneous. A second use for aluminium turns on the same quality; it was
devised by Dr. Goldschmidt for producing high temperatures, and is
especially useful in welding steel rails and pipes. A mixture of iron oxide
and aluminium finely divided is ignited by a magnesium ribbon; a very high
temperature results as the aluminium combines with the oxygen derived
from the iron oxide.
Aluminium by reason of its lightness occupies a large field in naval and
military equipments, in motor-car construction, and the like, where the
reduction of weight is of paramount importance. For cooking utensils the
use of aluminium is constantly extending; the metal is a capital conductor
of heat, is not liable to deteriorate in use, and gives rise, if dissolved, to
harmless compounds. The chief objection to aluminium is its low tensile
strength, which, for the cast metal is only 10,000 to 16,000 pounds per
square inch. An improvement is effected by adding as an alloy a small
quantity of some other metal, such as nickel or copper. When one part of
aluminium is joined with nine parts of copper we have aluminium bronze,
the strongest and handsomest of copper alloys, much resembling gold in its
lustre.
Aluminium is finding acceptance as an electrical conductor. An installation
of this kind in Canada unites Shawinigan Falls with Montreal, 84.3 miles
distant. Three cables are employed, each composed of seven No. 7 wires.
The total loss in the transmission of 8,000-horse power, at 50,000 volts at
the generating station, is about eighteen per cent. Comparing equal
conductors, in round numbers the cross-section of an aluminium cable is
one-and-a-half times that of a copper cable, the weight being one-half and
the tensile strength three-quarters. Everything considered when aluminium
is 21⁄10 the price of copper, the investor is equally served by both metals as
conductors. This is true only where the conductors are bare. Where
insulated cables are needed, the increased diameter of an aluminium
conductor entails extra cost for insulating material.

At first the lightness and weakness of aluminium were
Properties at First
much against it; these, as we have seen, were soon Unwelcome are
overcome by alloying the metal with copper or nickel. Turned to
Account.
But by giving aluminium forms of utmost stiffness, by
reinforcing these forms with steel wires, the metal is
quite strong and rigid enough for cups, plates, cameras and other
instruments for which lightness is most desirable. In many another case a
material or a characteristic at first unwelcome has been turned to excellent
account. Smokiness in a fuel is not a quality mentioned in its
advertisements, and yet smokiness is just what is sought in the twigs,
stubble, or coals set on fire to give plants a cloud protecting them from
unseasonable frosts. It is astonishing how little fuel will serve in such cases,
especially if the atmosphere is calm, so as not to carry the smoke where it is
not needed. Many another instance might be given of a quality
objectionable for one service and then turned to satisfying a new want.
Sometimes, too, offensive qualities are most useful. Illuminating gas, as at
first manufactured, had a distressing odor, which gave prompt and
unmistakable notice of a leak. When water gas came into use, most harmful
when inhaled, the chemists were puzzled to know how to give it an
offensive smell; they found that a quality long complained of was really an
advantage in disguise.
So in the electrical field, when an unsought quality has intruded itself, and
proved unwelcome, the question has arisen, what service can we enlist it
for? Not seldom the answer has been gainful in the extreme. Dr. Oliver J.
Lodge tells us that a bad electrical contact was at one time regarded simply
as a nuisance, because of the singularly uncertain and capricious character
of the current transmitted by it. Professor Hughes observed its sensitiveness
to sound-waves, and it became the microphone, which, duly modified,
brought the telephone from the whisper of a curious toy to the full tones
which ensured commercial success the world over. This same “bad” contact
turns out to be sensitive to electric waves also, forming indeed nothing else
than the coherer of the wireless telegraph.
Many an electrician has been perplexed and thwarted by the small bubbles
of air which place themselves on a metallic surface immersed in an electric
bath, interrupting the attack sought to be carried to a finish. Happily there is
a task which these very bubbles perform as if they had been created for no

other purpose, namely, the re-sharpening of files. First the dull and dirty
files are placed for twelve hours in a fifteen to twenty per cent. solution of
caustic soda; they are then cleaned with a scratch-brush and a five per cent.
soda solution. Next they are placed in a bath of six parts of forty per cent.
nitric acid, three parts sulphuric acid, and 100 parts water, each file being
connected to a plate of carbon immersed close to it, by means of a copper
plate connecting at the top all the carbons and the files. This produces a
short-circuited battery generating gas at the surface of the files; the bubbles
which adhere to the points of the files protect them from being eaten away,
while the rest of the metal is being etched. Every five minutes the files are
taken out and washed in water to remove the oxide which collects on their
surfaces. When sufficiently etched they are placed in lime-water to remove
any adherent acid, dried in sawdust to prevent rusting, and rubbed with a
mixture of oil and turpentine. Indispensable in the whole process is the
protection afforded by the bubbles of air.
For a long time its creation of sparks kept electrical
Evil, Be Thou My
machinery out of mines liable to fire-damp, which might Good.
be exploded by these sparks. In many other places they
worked evils quite as serious, setting fire to shavings, cotton and such like.
To-day these very sparks are applied to touching off the charges of gas and
air in gas-engines of all types, whether stationary, or for automobiles and
motor-boats. In another respect the automobile should be provided with a
means of creating what is usually considered a nuisance, namely, a noise.
Moving rapidly as it does on thick rubber tires, it gives no warning to
hapless wayfarers. In Canadian cities, where in winter deep snow may
muffle the tread of horses, every sleigh, under severe penalty, must be
furnished with efficient bells.
Sometimes an important property has unwelcome effects
Compensating
which, in particular cases, cannot be applied to Devices.
advantage, and must be counterbalanced with as much
care as possible. Many pieces of mechanism from the qualities of their
materials are subject to deviations which must be compensated by
introducing equal and opposite action. Tasks of this kind proceed upon an
intimate acquaintance with the properties of substances common and
uncommon. From the first making of clocks there was much trouble due to
changes of temperature which affected the dimensions of pendulums, and

consequently their rate of going. This difficulty is overcome by taking
advantage of the fact that heat expands zinc about two-and-a-half times as
much as it expands steel. Accordingly the two-second pendulum of the
great clock at Westminster is built of a steel rod 179 inches in length, and a
zinc tube, less massive, 126 inches long; they are joined at their lower ends
only and are parallel. As temperatures vary, the fluctuations in length of the
steel compensate those which occur in the zinc. Another mode of effecting
the same purpose is to employ a cylinder partly filled with mercury; as this
rises when warmed it exactly compensates for the lengthening by expansion
of its supporting rod of steel.
Gravity, that universal force at which we have just glanced as it swings a
pendulum, cannot be banished, but its downward push may be balanced by
an equal upward thrust. In a remarkable feat Plateau poured oil into a blend
of water and alcohol, adding alcohol until he produced a mixture having the
same specific gravity as the oil—which now became a sphere, taking its
place in the middle of the diluted spirits. He then introduced into the oil a
vertical disc which he rotated; very soon spherules of oil separated
themselves from the parent mass, and as satellites moved in the same
direction as the primary sphere, because immersed as they were in the
diluted alcohol, they shared the direction of its motion: the whole afforded a
remarkable illustration of how nebulae may become planets, moons, and
suns.
On somewhat the same principle as Plateau’s model are the liquid
compasses for ships. Their needles are disposed within hollow metallic
holders of the same specific gravity as the immersing liquid, in which
therefore they move with perfect freedom on their sapphire bearings.
Sometimes it is desired to use compass needles so poised that they will
respond to the slightest magnetic influence. To this end one needle is placed
above another, the north pole of the first over the south pole of the second;
the astatic needle formed by this union is much more sensitive than a simple
needle. The astatic needle, for all its ingenuity, is little used; of
incomparably more importance is that other magnetic device, the telephone.
No sooner had it entered into business than a serious fault was found with
its messages; they arrived blurred and mingled with many sounds and
noises, as if the conveying wire had caught every audibility of a
neighborhood. The difficulty is remedied by using two conductors instead

of one, and so arranging them that the currents induced on one conductor
are exactly equal and opposite to those induced in the other.
If properties at first unwelcome have at last been turned Properties Long
to account, so also have properties which were long Deemed Useless
deemed utterly useless. A big and interesting book might are Now Gainful.
be filled with the story of how by-products, long thrown
away as worthless, have rewarded careful study with great profit. Thus for
ages was bran discarded in flour-mills: to-day it may afford all the miller’s
profit, or even more than that profit. In the Southern States until a
generation ago cotton seed was regarded as valueless. At present that
product, so long wasted, is the basis of a great industry, a ton of seed
yielding about 1089 lbs. of meat to 20 lbs. of lint; out of this meat 800 lbs.
are cake and meal; the remainder, 289 lbs., forms an oil which furnishes a
substitute for olive oil and lard. Until a few years ago glycerine was thrown
away as produced in candle-works and soap factories. It is now so valuable
that manufacturers adopt just that method of preparing fatty acids which
yields most glycerine from neutral fats. So in paper-making, the soda which
formerly was sent into creeks and rivers to the pollution of sources of
water-supply, is now used over and over again, largely increasing the net
results of manufacture. No industry has shown of late years so large
utilization of products formerly wasted as the iron and steel manufacture.
Its slags are made into bricks, cement, and glassy non-conductors of heat
and electricity. Its gases are used for engines developing immense motive
powers, or they are in part condensed for valuable acids or other
compounds. In these cases and thousands more the question has been, What
are the properties of these by-products? How can they be made useful?
Let us note how diverse substances are separated from
Separation Turns
one another by taking hold of differences in their on Diversity of
properties. When a handful of grain which has just Properties.
passed under a flail is thrown upward in a breeze, its
chaff is blown much farther than the grain; the difference in breadth of
surface, joined to a difference in density, enables the wind to effect a
thorough separation. A common fanning mill, with its quick air current,
works much better than the fitful wind, because continuously. That simple
machine, like every other which takes a mixture and separates its
ingredients, seizes upon a difference in properties. In Edison’s apparatus for

removing iron from sand or dust, a series of powerful magnets overhang a
stream of sand or powdered material, deflecting the iron particles so that
they fall into a bin by themselves, while the trash goes into an adjoining
larger bin. The Hungarian process of flour-milling first crushes wheat
through rollers; the various products are then separated by processes which
lay hold of differences in specific gravity—often but slight.
A feat more difficult than that of the Hungarian mill would seem to be the
division of diamonds from other stones. It has been accomplished by Mr.
Frederick Kersten of Kimberley, South Africa. He noticed one day at his
elbow a rough diamond and a garnet on a board. He raised one end of this
board, and while the garnet slipped off, the diamond remained undisturbed.
What was the reason? He observed that the wood bore a coating of grease,
which possibly had held the diamond while the garnet had slipped away. He
took a wider board, greased it, and dropped upon it a handful of small
stones, some of which were rough diamonds. He found that by inclining the
board a little, and vibrating it carefully, all the stones but the diamonds fell
off, while the diamonds stuck to the grease. He forthwith built a machine
with a greasy board as its separator, and scored a success.
On quite a different plan is built the coal washer which separates coal from
slate. Pulses of water are sent upward through a sieve so as to strike a
broken mixture of coal and slate, making a quicksand of the mass. Because
the slate is heavier than the coal it is not carried so far, and is therefore
caught in a separate stream and thrown away.
Separations, such as we just considered, turn upon
Properties Newly
obvious differences in density. Properties not obvious, Discovered and
yet highly useful, come into view year by year as Produced.
observers grow more alert and keen, as new instruments
are devised for their aid, as measurements become more refined, so that
matter is constantly found to be vastly richer in properties than was
formerly supposed. We have long known that carbon has forms which vary
as widely as coal, graphite and the diamond. Many other elements are
detected in a similar masquerade. Iron, for instance, takes three forms,
alpha, beta, and gamma. Alpha iron is soft, weak, ductile and strongly
magnetic; beta iron is hard, brittle and feebly magnetic; gamma iron is also
hard and feebly magnetic, yet ductile. Joule, the famous English

experimenter, prepared an amalgam of iron with mercury; when he distilled
away the mercury, the remaining iron took fire on exposure to the air,
proving itself to be different from ordinary iron. Moissan has shown that
similar effects follow when chromium, manganese, cobalt and nickel are
released from amalgamation with mercury.
At first steel was valued for its strength and elasticity; to-day we also
inquire as to its conductivity for heat or electricity, its behavior in powerful
magnetic fields, its capacity to absorb or reflect rays luminous or other. As
art moves onward we enter upon new powers to change the properties of
matter, compassing new intensities of heat and cold, each with new effects
upon tenacity, elasticity, conductivity. So also with the extreme pressures,
possible only with modern hydraulic apparatus, which prove marble to be
plastic, and reduce wood to a density comparable with that of coal,
explaining how anthracite has been consolidated from the vegetation of
long ago.
And one discovery but breaks the path for another, and so on indefinitely.
Coming upon a new property, the sensitiveness of silver compounds to
light, meant a new means of further discovery, the photographic plate. That
plate, responsive to rays which fall without response upon the retina,
reveals much to us otherwise unknown and unsuspected. Of old when an
observer saw nothing, he thought there was nothing to see. We know better
now. Thanks to the sensitive plate we have reason to believe that properties,
once deemed exceptional, are really universal. Phosphorescence, for ages
familiar in the firefly, in decaying logs and fish, now declares itself
excitable in all substances whatever, although usually in but slight measure.
The case is typical: the polariscope, the spectroscope, the fluoroscope, the
magnetometer, the electroscope, each employing as its core a substance of
extraordinary susceptibility, detects that quality in everything brought
within its play. Thus from day to day matter is disclosed in new wealths of
properties, and therefore in new and corresponding complexities of
structure. In ages past mankind was on nodding terms with many things,
and had no intimate knowledge of anything.
With materials before him richer in array than ever before, and better
understood than of old, the inventor asks, What properties do I wish in a
particular substance? Then, he proceeds to make, if he can, a dye of

unfading permanence, an insulator resistant to high temperatures, an alloy
which when subjected to heat or cold remains unaltered in dimensions. He
finds materials much more under command than a century ago could have
been imagined, as the glass manufacture, the alloying industry, the making
of artificial dyes, abundantly prove.
Mr. Edison, for aid in finding just the substance he needs
Edison’s
for a new purpose, has at his laboratory in Orange, New Warehouse as an
Jersey, a large store-room filled with materials of all Aid.
kinds. He may wish a particularly high degree of
elasticity, hardness, abrasive power, or what not; to provide these he has
gathered a wide diversity of woods, ivories, fibres, horn, glass, porcelain,
metals pure and alloyed, alkalis, acids, oils, varnishes and so on. Take one
example from among many which might be given from his shelves; he finds
that a sapphire furnishes the best stylus wherewith to cut a channel on a
phonographic cylinder. Hard, flinty particles from the air are apt to enter the
wax, so as to blunt a cutting edge. Diamonds would be best as channelers,
but their cost obliges him to choose sapphires as next best; they are
purchasable at reasonable prices and last ten years under ordinary
conditions of wear.

CHAPTER XII
PROPERTIES—Continued

Producing more and better light from both gas and electricity . . . The Drummond light . . . The
Welsbach mantle . . . Many rivals of carbon filaments and pencils . . . Flaming arcs and tubes of
mercury vapor.

Mr. Edison has achieved triumphs not only in giving Light Giving
sound its lasting registration, but in producing an electric Properties.
light of new economy. Both exploits proceeded upon a
masterly knowledge of properties. A century ago candles provided
illumination both to rich and poor, the sole difference being that wax shone
in the palace and tallow in the hut. The oil lamps which gleamed in the
lighthouses of England and America, for all their bigness, were plainly of
kin to the Eskimo saucer filled with blubber, edged with moss as wick. Yet
for ages, from every hearth in Christendom, there had been the promise of
better things as bituminous coals, or sticks of wood, had cheered as much
by their light as by their warmth. We owe much to James Watt, who
improved the steam-engine and gave it essentially the form it retains to the
present hour. We owe also a weighty debt to an assistant of his, William
Murdock, who, thanks to a suggestion from Lord Dundonald, attentively
observed the process by which coals produce light. He saw that under stress
of intense heat the solid fuel emitted streams of gas which burned with great
brilliancy. Here gas-making and gas-burning went on at the same moment
in the same place; might the process be separated, so that gas might be
made here, and burned elsewhere at any convenient time? An experiment
proved the project to be feasible, and forthwith the Soho Works, near
Birmingham, in which Watt’s engines were built, were lighted by gas. Such
was the beginning of an industry now important in many ways. To-day gas
not only yields light, but heat and power, while, especially in metallurgy,
fuels are more and more used after reduction to the gaseous form.
Early in the day of gas-making it was noticed that gases How the Gas
of various kinds differed much in light-giving quality. It Mantle was
was presently shown that their light depended on the Invented.

carbon brought to incandescence in a flame; in the absence of that carbon,
as when a jet of pure hydrogen was consumed, extreme heat was
accompanied by no light whatever. Then came a capital discovery, namely,
that lime introduced within a burning jet of hydrogen became intensely
luminous while itself but slowly consumed. Adopting lime for the core of
his apparatus, Captain Thomas Drummond, of the Royal Engineers, in 1835
devised the lime light. Upon a block of pure, compressed quick lime, he
directed a jet of burning gas, obtaining a beam of great vividness still
employed in stereopticons and in theatres. For modern types of the
Drummond lamp a twin jet of hydrogen and oxygen is used. Lime has many
sister substances having light-giving quality when highly heated, and
among them are many rare earths, oxides of uncommon elements. These
strange substances were destined to play a prominent part in the battle
between gas and electricity as illuminants. When Edison in 1878 perfected
his incandescent bulb, it seemed as if electricity were soon to be the sole
illuminator of houses. But the gas engineers were to be rejoiced by the
invention of a mantle which quadrupled the brillancy of a gas flame,
withstanding the rivalry of electricity in a notable degree. This mantle was
invented by Dr. Auer von Welsbach, a chemist of Vienna, who virtually
adopted the principle of the Drummond light. His efforts give us an
admirable example of an inventor passing from a hint to a test, day after day
meeting new difficulties with unfailing courage and resourcefulness.
In 1880 Dr. von Welsbach took up the study of rare earths, mainly with a
view to ascertaining their value as illuminants. As he brought one specimen
after another to melting heat on bits of platinum wire, he found that the little
beads formed were unfavorable in shape to the production of light. Then
came into his mind an idea of that golden quality which occurs only to the
man who earns it: Why not soak cotton with solutions of salts of rare earths,
burn the cotton and leave behind an earthy skeleton of slight thickness and
much surface? Experiment proved that the idea had promise, but the
skeletons crumbled to dust with the least tremor. For success a fair degree
of cohesion was imperative, but to secure that cohesion demanded skill,
resource, and patience. After a long series of trials a mantle was made with
lanthanum oxide; immersed in flame its beam was particularly bright, now
for the first time suggesting that the rare earths might yield light on a large
scale. But trouble was at hand, to be overcome only at the end of much toil.

During an absence of several days, the inventor left a mantle of lanthanum
oxide locked up in his laboratory. When he returned it had fallen to powder,
having attracted from the atmosphere both moisture and carbon dioxide.
Evidently this harmful attraction must be avoided by adding an ingredient
to keep the mantle dry and preserve it from union with carbon dioxide. For
this purpose magnesia was chosen; the resulting compound proved to be
durable, and gave an agreeable light of moderate intensity. But, alas, after
glowing about seventy hours, the mantle failed in its radiance, becoming of
glassy and translucent texture. Thus impeded, the untiring inventor turned
to mixtures having zirconium as a basis; these not only gave a steady beam,
but extended to hundreds of hours the life of a mantle. Still bent on getting
more light if he could, Dr. von Welsbach tested thorium oxide with
gratifying results; yet, strange to say, when he had purified this material to
the utmost, his light fell off in an unaccountable fashion. What could be the
matter? Surely in the purifying process some invaluable element had been
cast aside. This element, in the researches of an associate, Mr. Ludwig
Haitinger, proved to be cerium in minute quantity. Here was a discovery of
the highest moment; at the end of many experiments it was determined that
one per cent. of cerium and ninety-nine per cent. of thorium oxide are the
best proportions for a mantle such as we use to-day. Why these proportions
are best nobody knows, any more than why one per cent. of carbon added to
iron gives us a steel incomparably better than iron for many uses. A
Welsbach mantle has good points apart from its economy of gas. Its
combustion is thorough, so that it throws into the air a much lower
percentage of injurious products than does an ordinary gas flame. It never
smokes, and its light is so steady as to be available for work with the
microscope and other exacting demands. It has one defect which may yet be
removed: its light has a somewhat unpleasant tinge of green. In another
chapter of this book, producer gas, much cheaper than common
illuminating gas, is described. Dowson producer gas, with a Welsbach
mantle, yields a light of 8 to 10 candle-power with a consumption of 4.5 to
4.8 cubic feet per hour.

Dr. CARL FREIHERR AUER von WELSBACH
of Vienna.

Boivin burner for alcohol,
attachable to any lamp.

Thus far no successful mantle for a petroleum lamp has been devised. With
alcohol a mantle yields a brilliant flame. A lamp with a Boivin burner and a
Welsbach mantle has given a light of 30.35 candle-power for 57 hours and 5
minutes in consuming one gallon of alcohol, almost twice as much light as
given by a Miller lamp with a round wick and a central draft, burning a
gallon of kerosene. In the United States on January 1, 1907, there will cease
to be an excise tax on alcohol used in the arts, a denaturalizing process
rendering the liquid unfit to drink. As this alcohol may be easily produced
from grain or potatoes at 20 to 25 cents a gallon, a capital illuminant will be
available for the public, as well as an excellent fuel and a substitute for gas
or gasoline in motors.

As first manufactured, gas-mantles were woven, they are now knitted,—a
change for the better in closeness and firmness of texture. Nearly all the
thorium used for mantles is found in the monazite sands of the provinces of
Bahia and Espirito Santo, along the coast of Brazil. These sands were for a
long time valuable only for the zinc they contained. To-day the thorium
they carry is of vastly more account; for chemical treatment this is sent to
Germany whence the manufactured product is borne to every quarter of the
globe.
While the Welsbach mantles have been constantly
Improvements in
improved in quality, and given new and inverted forms Electric Lighting:
of special value, the inventors in the field of electric Incandescent
Lamps.
lighting have not stood still. For interior illumination the
Edison incandescent bulb still holds its own despite
many a threat of dispossession. Since 1881 its details of manufacture have
been steadily bettered and its price much reduced, while its consumption of
current has fallen from 5.8 watts per candle to 3.1. This advance, marked as
it is, leaves a long path ahead of the inventor whose estimate is that were
the whole of an electric current transformed into light, a candle would cost
us but .11 of a watt, that is, but one twenty-eighth part as much as when we
set a carbon filament aglow. In electrical terms a horse-power yields 748
watts, representing, were there no waste in conversion, no less than 425
lamps each of 16 candle-power.

Alcohol lamp with ventilating
hood.

It is this immense margin for improvement that has spurred ingenuity to
attack the problem of electric lighting from many new sides. The General
Electric Company produces a carbon filament of one fifth greater efficiency
than an ordinary untreated filament. Fibers of the usual cellulose kind are
enclosed in a carbon box, placed in a carbon-tube resistance furnace heated
to between 3,000° and 3,700° C. This converts the filament into a graphite
of increased luminosity which, furthermore, blackens its enclosing glass
much less than a common filament does.

Welsbach mantle.

In the early days of electric lighting a good many experiments were tried
with threads of platinum, but without success. That metal remains unmelted
at a very high temperature, but as a light-giver its quality is poor. Of late
years investigators have turned to other metals, of high melting points, and
with results so remarkable that we may expect some of them to be in
general use in the near future. Tantalum, a rare and costly metal, has been
found to give a candle-power with as little as two watts and, in specially
favorable circumstances, with only 1.85 watts. Osmium, in the hands of Dr.
Auer von Welsbach, reduces this figure to 1.5 watts. Dr. Hans Kuzel, of
Baden, Austria, has employed filaments of tungsten in lamps which he
claims demanded only one watt per candle. From among these new lamps it
seems highly probable that as soon as methods of manufacture are settled
and standardized the world will be given an electric light, in small units,
much cheaper than ever before.

Tantalum lamp.

Tungsten lamp of Dr. Hans
Kuzel.

For large spaces indoors and for out of doors the arc-lamp
New Arc Lamps.
maintains its popularity in much the form originally
devised by Mr. Charles F. Brush of Cleveland. But, as in
the case of the incandescent bulb, many a rival is now disputing the field, so
that supersedure may be close at hand. In what are known as flaming or
luminous arcs the carbon pencils are impregnated with salts of the calcium
group of elements, of extreme luminosity. In these lamps the electric arc
itself is the chief source of light, instead of the glowing end of the positive
carbon as in a common arc lamp. As the calcium salts volatilize into gases
they provide a path of less resistance than air for the passage of the current,
so that the electrodes may be drawn apart to a distance which may be as
much as 21⁄2 inches. These lamps require free ventilation, so that they must
be open. Their economy is extraordinary, a candle-power being afforded for
.353 watt, as against 1.78 watts for an enclosed arc lamp, a five-fold gain in
effectiveness. To renew the carbons, which waste rapidly, a new device
provides fresh pencils, cartridge fashion, as required. Without this aid,
trimming is often necessary, and this fact joined to the high cost of the
carbons lessens the net gain in their use. On another line of experiment
noteworthy results have been reached with metallic oxides. Magnetite, an
oxide of iron, has developed a candle-power with but one half of one watt.
Ferro-titanium, a compound of iron and titanium, has given a candle-power
with only one third of a watt, and it is expected that still higher efficiencies
will soon be attained with this wonderful compound.

Hewitt mercury-vapor lamp.

From quite another side Mr. Peter Cooper Hewitt enters
Hewitt Mercury-
the field of light production, utilizing the glow of a vapor Vapor Lamp.
instead of a solid stick. His lamp is a long, slender tube
of glass; within each end is sealed a metallic wire; at one end is a little
mercury. When a powerful pump has exhausted the tube to a high degree it
is sealed, and its wire terminals are placed in an electric circuit. On tilting
the tube the mercury flows from end to end, an arc is formed, and the
mercury vapor becomes luminous. This vapor remains unconsumed, and the
lamp asks no attention whatever. Its rays are greenish, so that where normal
colors are desired, it is well to use supplementary lamps of carbon filaments
to furnish red rays. For streets, squares, freight-sheds and the like, the
Hewitt light is capital just as produced, its rays being widely diffused and
casting no heavy shadows. Its high actinic power makes it specially useful
to photographers, while in factories, drafting rooms, composing rooms and
so on, its color is unobjectionable. Its cost is small, as a candle-power is
produced in large tubes with but 0.55 of a watt. A Hewitt lamp of automatic

type, recently devised, has a small solenoid or magnet on the suspension bar
just above the holder. On closing the circuit the current flows through this
solenoid which instantly tilts the tube and starts the light. This lamp is
particularly suited to places, such as the lofty ceilings of foundries, where it
would be difficult to tilt the tube by hand. Hewitt lamps use either a direct
or an alternating current.
In an earlier chapter we glanced at reflectors and refractors, newly invented,
which give light its most useful paths with as little avoidable loss as
possible. These devices, applied to Welsbach burners and the new electric
lamps, greatly economize modern illumination in comparison with that of
former times.[13]
[13] In February, 1906, the Illuminating Engineering Society was established in New York.
Its secretary is A. H. Elliott, 4 Irving Place, New York. The Society publishes its
proceedings and discussions.

CHAPTER XIII
PROPERTIES—Continued. STEEL

Its new varieties are virtually new metals, strong, tough, and heat resisting in degrees priceless to the
arts . . . Minute admixtures in other alloys are most potent.

rom a brief consideration of illuminants let us pass to a rapid survey of
F a most important group of structural materials, the steels. Here, as
always, we shall find how abundant are the harvests reaped in a
searching study of properties. Within the past fifty years new steels have
been produced in so ample and rich a variety that we have gained what are
virtually many new metals of inestimable qualities.
In 1781 Professor Torbern Bergman, of the University of Steels for
Upsala, in Sweden, showed that steel mainly differs from Strength.
iron in containing about one fifth of one per cent. of
plumbago, or carbon, as we would say now. Steels may contain all the way
from one tenth to one and a half per cent. of carbon; the lower this
percentage, the more nearly does the steel approach wrought iron in
softness; as the proportion of carbon increases up to one per cent. the steel
increases in tenacity, beyond one per cent. tenacity diminishes and
brittleness is augmented. Hardness depends upon the percentage of carbon a
steel contains. Physical conditions are almost as important as chemical
composition; a mass of red-hot steel, carefully hammered or pressed is
thereby strengthened, an effect due either to minimizing the process of
crystallization, or to breaking up crystals as fast as they form. The
microscope reveals many details of structure in steel, and has enabled the
analysts greatly to economize the manufacture of desired varieties. Under
the microscope steels much resemble crystalline rocks in structure, with
constituents differing widely. Of these the most important is ferrite, a pure
or nearly pure metallic iron, soft, weak, ductile, of high electric
conductivity. Next in importance is cementite, an iron carbide (Fe3C),
harder than glass and nearly as brittle, but probably very strong under
gradually and axially applied stress. A third constituent, austenite, is a solid
solution of carbon, or perhaps of an iron carbide, in gamma allotropic iron

(there being also alpha and beta irons). Austenite is hard and brittle when
cold, is stable at high temperatures, and is slowly transformed by reaction
into compounds of ferrite or cementite. Several other ingredients of
importance, as pearlite, illustrated on the opposite page, have also been
studied.[14]
[14] Henry Marion Howe, “Iron, Steel and Other Alloys.” Second edition. Published by
Albert Sauveur, Cambridge, Mass., 1906.

While carbon is the most decisive element in admixture, other ingredients
have marked influence, silicon and manganese especially. The process
invented by Bessemer, described by himself in another chapter of this book,
as introduced in 1855, revolutionized the steel manufacture by its
directness, cheapness and speed. It consists in burning out from pig-iron, by
a hot air blast, all or nearly all its carbon. Then spiegeleisen, or other
mixture, containing a definite quantity of carbon and manganese, is added
to the molten mass, yielding steel of the quality desired. This method
produces more rails for railroads than any competing method; in other fields
it is being rivalled more and more severely by the open hearth process.

Pearlite, magnified about 750 diameters. Steel containing more than nine-tenths of one
per cent of crystals of pearlite, surrounded by
envelopes of cementite (Fe3C). Magnified 200
diameters.

CLEANING CARS BY THE “VACUUM” METHOD.

Steel making by the open hearth process is chiefly due to
The Open Hearth
the late Sir William Siemens. In a gas producer he gave Process.
his fuel the gaseous form, in which it is more easily
controlled and more efficient than when solid. Of more importance were his
regenerators, chambers of brickwork, heated by the products of combustion,
and then employed to warm incoming currents of air and gas on their way
to the furnace. The Siemens furnace has been modified in many ways and
much improved in its details. A good example of an open hearth furnace, as
planned by the late Mr. Bernard Dawson, is shown on page 165. It centers
in a large hearth built of refractory materials, upon which the metal is
melted as flames play over it. At each end are two regenerators filled with
checker firebricks through which air or gas passes on its way to the furnace,
and through which, at due intervals, the products of combustion emerge as
they pass to the stack. On each side, one of the regenerators is for air, the
other for gas; between them is a substantial wall to prevent any mixing
before their currents reach the hearth. It is in the regenerator, which utilizes
heat which otherwise would be wasted, that the open hearth displays its best

feature. Its products vary in composition as its raw materials vary, whether
pig-iron of a specific kind, a particular ore, or scrap; and just as in the
Bessemer process, a harmful element, as phosphorus, is removed almost
wholly by the addition of a suitable ingredient, such as lime. In excellence
and uniformity of quality open hearth steels are preferred to those of the
Bessemer converter, even for railroad rails which for years were made
solely by the Bessemer process.

Open hearth furnace.

A remarkable improvement in blast-furnace practice, The Gayley Dry-
cheapening cast or pig-iron, and therefore lowering the Blast Process.
cost of derived steels, is the dry-blast process due to Mr.
James Gayley, of Pittsburg. It has long been known that blast-furnaces ask
more fuel in warm and damp weather than in cold and dry weather;
beginning with this familiar fact Mr. Gayley proceeded to dry the air blown
into his furnaces, by passing it around large coils of iron pipes through
which a freezing mixture circulated, melting the snow as formed by passing
hot brine through the pipes, a few of them at a time. The air thus dried was
then heated by being sent through hot blast stoves in the usual mode. This
simple drying of the blast saves about 19 per cent. of the fuel, and makes
the action of the furnace much more regular than when ordinary air is used.

It lowers the temperature of the gases which escape from the top of the
furnace, and raises their percentage of carbon dioxide, symptoms of the
great increase in fuel efficiency. Atmospheric moisture has a cooling effect
on the lower part of a furnace, just where the highest temperature is needed
to melt the iron and slag, remove the sulphur and deoxidize the silica. A
comparatively small increase of temperature by broadening the margin of
effective heat, which margin at best is narrow, has the astonishing effect of
economizing fuel to the extent stated, 19 per cent.[15]
[15] Henry Marion Howe, “Iron, Steel and Other Alloys.” Second edition. Cambridge,
Mass., Albert Sauveur, 1906.

What is chiefly sought in steel is tensile strength, next in Steels to Order.
value is elasticity; in some cases hardness is indispensable.
By varying the proportions of the carbon, silicon and manganese added to
his iron, the steel-maker produces an alloy with the tenacity, elasticity or
hardness he wishes. Nickel, as a further ingredient, in certain proportions
yields an astonishing gain. A steel containing fifteen per cent. of nickel has
shown a tensile strength of 244,000 pounds to the square inch, four times as
much as before admixture; the elastic limit also was much increased.
Hardness and strength tend to exclude ductility, but nickel steel is at once
strong, hard and extremely ductile; hence its use for armor plate, great guns,
and the barrels of small arms. Nothing but the high price of nickel prevents
these alloys from having wide utilization, for they mean lighter and
therefore more economical machines and engines than those of ordinary
steel. Many turbines actuated by water, steam or gas, are best operated at
speeds forbidden to common steel, which would fly to pieces under the
centrifugal stress exerted, yet these speeds are quite feasible and safe when
nickel steel is employed. This alloy brings nearer the day of mechanical
flight, first promising to transportation on land and sea engines increased in
power while much diminished in weight. In exceptional cases, where the
expense may be borne, we may expect soon to see nickel steel used for
higher towers, longer bridge-spans, thinner boilers, than those of to-day.
Part of the bridge crossing Blackwell’s Island, New York, is built of nickel
steel. Even with costs at their present plane, it is worth while for the
designer of machinery to remember that friction is reduced when masses
become smaller, power for power. It is found profitable, for instance, to use
nickel steel for the cylinders of automobiles of high power.

In many tools and implements two different kinds of steel are united with
decided gain. Thus the cutting edge of a cold chisel is hard and brittle, while
its shank, much less hard, is tough and able to resist the shocks it receives.
So also a projectile is hardened at its point and nowhere else. Plowshares
are often made very hard on their surfaces, with a backing which is
comparatively soft but elastic enough to suffer no harm in the blows dealt
by rough ground and stones. One of the drawbacks in the use of steel is its
liability to corrosion. An alloy of 30 per cent. nickel and 70 per cent. steel
has proved to be corrodible in but slight measure, affording a material of
great value to the arts.
While the chemical composition of a steel is of prime Heat Treatment.
importance, the quality of the steel will next depend upon
its heat treatment in manufacture. The temperature to
which heating is carried, the period during which it is maintained, the rate at
which cooling takes place, and the circumstances of cooling, each has its
effect on the character of the product. It is chiefly in this field that the steel-
maker within wide limits is able to turn out an alloy either hard or soft,
brittle or ductile, tenacious or weak, at pleasure. While much has been
learned within the past few years as to the proper treatment of steel by heat,
much still remains to be discovered.
To quote typical instances from Professor Henry Marion Howe, of
Columbia University, New York:—“In the case of steel with less than 0.33
per cent. of carbon the temperature from which slow cooling occurs appears
to have little influence on the tensile strength; but it is the general belief that
if that temperature approaches the melting-point, the tensile strength
decreases. In the case of higher-carbon steel, the tensile strength at first
increases as the temperature from which slow cooling occurs rises to 800°,
or even to 900° or 1000° C. Then, after varying somewhat, it falls off very
abruptly in the case of steel of 0.50 per cent. of carbon, when that
temperature approaches 1400°.”[16]
[16] In his “Iron, Steel and Other Alloys.” Second edition. Published by Albert Sauveur,
Cambridge, Mass., 1906.

For rock drills, cold chisels, milling and other tools it is Tempering and
necessary to use steel carefully tempered, so that Annealing.
brittleness is greatly reduced while considerable hardness

and cutting power remain. Other changes of properties, as remarkable,
follow upon subjecting steel to greater heat than that used for tempering.
Says Professor Roberts-Austen:—“Three strips of steel identical in quality
are taken. By bending one it is shown to be soft; if it is heated to redness
and plunged in cold water it will become hard and will break on any
attempt to bend it. The second strip, after heating and rapid cooling, if again
heated to about the melting point of lead, will at once bend readily, but will
spring back to a straight line when the bending force is removed. The third
piece may be softened by being cooled slowly from a bright red heat, and
this will bend easily and remain distorted. The metal has been singularly
altered in its properties by comparatively simple treatment, and all these
changes, it must be remembered, have been produced in a solid metal to
which nothing has been added, and from which nothing has been taken
away.”
It is the comparative slowness of cooling in oil, the greater slowness of
cooling in air, that make these by far the best tempering processes, because
the molecular re-arrangement, in which tempering consists, requires time.
Often the critical temperature, at which a desired re-arrangement takes
place, is declared by the metal losing all power of response to a magnet: this
fact affords the steel-maker welcome aid; he has only to shut off heat as
soon as his steel ceases to attract a magnet and plunge the steel into water in
order to obtain the hardness he wishes.
The complex phenomena of heat treatment in steel manufacture are fully
discussed by Professor H. M. Howe, in his “Iron, Steel and Other Alloys,”
second edition, 1906.
In another chapter of this book a word is said as to the
Steel for Railroad
form of rails at which Mr. P. H. Dudley has arrived as the Rails.
outcome of years of experiment. He thus describes the
properties which the steel should possess by virtue of due chemical
composition and proper heat treatment:—
“Ductility to ensure power to resist the shock of the driving wheels, so that
the steel may not break; resistance to abrasion, that it may not wear out; and
high limit of elasticity, that it may not take a permanent set and be bent into
a series of waves between its supporting ties, by the enormous pressures

which the wheels of to-day throw upon it. The best composition is carbon
0.55 to 0.60 per cent., silicon 0.10 to 0.15, manganese 1.20, sulphur under
0.06, phosphorus under 0.06; with 50,000 to 60,000 granulations to the
square inch. More granulations, or fewer, mean an increase of brittleness in
the steel.”[17]
[17] Henry Marion Howe, “Iron, Steel and Other Alloys.” Second edition. Published by
Albert Sauveur, Cambridge, Mass., 1906. And a note from Mr. P. H. Dudley to the author,
May 2, 1906.

While the great strength of steel makes it of pre-eminent Invar: A Steel
value in the arts, steel in the huge dimensions of modern Invariable in
roofs and bridges has the demerit of expanding with heat Dimensions
Whether Warmed
and contracting with cold in a troublesome degree. A or Cooled.
notable case is that of the steel rails on the elevated
railroad of New York. If this fault, common to all metals, can be materially
reduced or abolished, then steel enters upon a new field of golden harvests.
Here, by dint of acumen and skill the goal has been reached by M. Charles
Edouard Guillaume, of the International Bureau of Weights and Measures in
Paris. A few years ago he began investigating the singular magnetic
qualities of nickel-steels. Then in studying expansibility by heat he
discovered that when the nickel was increased to 36.2 per cent. the alloy
was almost indifferent to changes of temperature, expanding but one part in
one million when warmed from zero to 1° Centigrade. Because of this
insensibility, the alloy at the suggestion of Professor Thury is named invar.
In observations of invar which extended through six years, an elongation of
one part in 100,000 was detected; subsequently its changes of length each
year seemed less than one-millionth. This slight inconstancy may be
overcome by further experiment; in the meantime while invar is not
available for standards of length of the first order, such as those of the
Bureau of Standards at Washington, there is a vast and useful field for the
alloy. It offers itself for secondary standards, to be compared at intervals
with primary standards at Washington or other capitals of the world.
A leading application will be in surveying. Already wires of invar have been
employed by the Survey of France with the utmost success, dispensing with
the burdensome apparatus formerly needed in compensating variations due
to temperature. With invar wires ten men have advanced at the rate of five
kilometers a day; ten years before, with ordinary steel measures, fifty men

advanced one half a kilometer, that is, with but one fiftieth as much
efficiency.
In time-keeping invar is likely to be as valuable as in surveying. At the
Bureau of Standards and the Naval Observatory at Washington, pendulums
of invar have been adopted with gratifying results. In ordinary watches and
clocks the alloy will banish the compensating devices now requisite, of
brass and steel which expand with heat and shrink with cold. For
chronometers of the highest grade it is desirable that invar be improved
with respect to its stability, an improvement which appears to be highly
probable.
One other discovery by M. Guillaume deserves a word. He has found a
nickel-steel which when warmed has the same expansibility as glass, so that
it may displace platinum wire in leading an electric current into an
incandescent lamp, a Crookes’ tube or similar illuminator. More singular
still is another of his nickel-steels which shrinks slightly when warmed,
holding out the hope of finding an alloy which will neither shrink nor
expand as its temperature rises. With such a substance, of trustworthy
stability, the arts would have a working material of inestimable value for
theodolites, frames for microscopes and telescopes, and cameras for exact
picturing.
The magnetic properties of steel, to-day of supreme Manganese Steel.
importance, have for ages excited curiosity. As long ago
as 1774, Rinman observed that steel alloyed with
manganese is non-magnetic. Here was a material for time-pieces which
would free them from magnetic derangement. In the hands of Mr. R. A.
Hadfield, of the Hecla Works, Sheffield, England, manganese steel has been
produced in remarkable varieties. As the proportion of manganese is
increased, the alloys manifest singular changes in their properties. When the
manganese is four to six per cent., and the carbon less than one-half per
cent., the alloy is brittle enough to be readily powdered by a hand hammer.
When the proportion of manganese is doubled, the alloy displays great
strength, which reaches its maximum when the manganese is fourteen per
cent. No other material approaches manganese steel in its ability to resist
abrasion; it outwears ordinary steel four times, much reducing the need for
repairs, renewals, or pauses in work while worn-out parts are being

replaced. It gives equally good service as the pins and bushings of dredges
of the bucket-ladder type, lifting gold-bearing gravels and sands. It is used
for centrifugal pumps in dredging sandy harbors, slips, or ponds, where the
grit borne in the water plays havoc with ordinary steel surfaces. In ore-
crushing manganese steel is particularly effective; a pair of jaws built of it
have crushed 21,000 tons of flinty ore and were still good for 4,000 to 6,000
tons more, while the best chilled iron plates failed to crush as little as 4,000
tons.
This alloy is so hard that it cannot be machined or drilled by ordinary
means; it must be treated by emery or carborundum wheels. Yet it is so
malleable that it can be used for rivets when headed cold. It is so tough that
it may be bent and twisted at will without rupture, so that it forms railroad
switches, frogs, and crossings of great durability.
Until 1868, the steel tools used in lathes and drills, High-Speed Tool
planers and so on, were limited to the moderate pace at Steels.
which they remained cool enough to keep their temper.
Beyond that quiet gait they became worthless, snapped apart, or melted as if
wax. In 1868 Robert Forester Mushet, of the Titanic Steel and Iron
Company, Coleford, England, discovered an alloy of steel, tungsten and
manganese which took rough cuts at a depth and with a speed unknown
before. This alloy, because hardened simply in air, was called “air-
hardening” or “self-hardening.” Thirty years afterward at the Bethlehem
Steel Works, Pennsylvania, a tool of this steel was heated to what was
feared to be a ruinously high temperature; experiment proved that the tool
could be used at a heat, and therefore at a speed, never attained before in the
workshop. From that hour hundreds of investigators have proceeded to
combine steel with tungsten in various percentages, adding manganese,
molybdenum, chromium, silicon, and vanadium. Of these ingredients much
the most important are tungsten and molybdenum. Particular pains must be
taken thoroughly to anneal the alloy when worked into bars.
As to the gain introduced by high-speed tool steels let Mr. J. M. Gledhill
testify from the experience of the Sir W. G. Armstrong, Whitworth &
Company’s works at Manchester:—

“Formerly where forgings were first made and then machined with ordinary
self-hardening steel, a production, from bars eighteen and one half by six
and five eighth inches, of eight bolts in ten hours was usual. With the new
steel forty similar bolts from the rolled bar are now turned out in the same
time, further abolishing the cost of first rough forging the bolt to form. The
speed is 160 feet a minute, the depth of cut three-quarter inch, of feed 1⁄32
inch, the weight removed from each bolt sixty-two pounds, or 2,480 pounds
per day, the tool being ground only once in that time. This is a fairly typical
case. Just as striking is the behavior of this steel in twist drills, which
supersede the punching process by passing through stacks of thin steel
plates quite as swiftly and economically as a punch, while avoiding the
liability to distress which accompanies the action of a punch.”
With the quickening of pace due to these steels, the designer is asked to
remodel machine tools so that they may stand up against new pressures and
speeds. A lathe thus re-patterned is mentioned by Mr. Gledhill: it absorbs
sixty-five horse power as against twelve formerly, and has a belt trebled in
width so as to measure twelve inches. Mr. Oberlin Smith expects high-
speed steel to have other effects on machine design than the conferring of
new strength: he looks for a rivalry keener than ever between rotary and
reciprocating tools. In his judgment the milling tool, which can be speeded
indefinitely, will encroach more and more on the planer, limited as the
planer is by its movement being to and fro.
When work on cast iron must proceed at the utmost pace, a jet of air,
delivered to the chips with force enough to clear them off as fast as they are
formed, enables the speed to be quickened, while, at the same time, the life
of the cutter is lengthened.[18]
[18] The foregoing pages on steel have been revised by Professor Bradley Stoughton, of
the School of Mines, Columbia University, New York. He contributes at the end of this
chapter a brief list of books for the reader who may wish to know something of the
literature of iron and steel.

In electrical art the alloy employed for electro-magnets Alloys for Electro-
should be permeable by magnetism fully and easily, Magnets.
otherwise dynamos and motors will waste energy as their
magnetism is constantly gained, lost, or reversed. Once more the
experimenter is Mr. Robert A. Hadfield of Sheffield, who produces an
excellent alloy by uniting iron with 2.75 per cent. silicon, .08 per cent.

manganese, .03 per cent. sulphur, .03 per cent. phosphorus. This alloy is
improved by being heated to between 900° and 1100° C., followed by quick
cooling; then being reheated to between 700° to 800° C., and cooled very
slowly.
Iron is largely used as an electrical conductor, so that it is well to know how
its conductivity is affected by ordinary admixtures. In experiments with
sixty-eight specimens, Professor W. F. Barrett alloyed iron separately with
carbon, aluminium, silicon, chromium, manganese, nickel, cobalt, and
tungsten. In every case there was a loss of conductivity, and usually in a
degree proportioned to the atomic weight of the added ingredient. Between
one element and another there was often a wide disparity of effect. For
example, in admixtures, each of one per cent., tungsten increased the
resistance of a conductor by two per cent., while aluminium did seven-fold
as much harm.
We have so long been accustomed to thinking that there Magnetic Alloys of
must be iron in everything magnetic that we hear with Non-Magnetic
astonishment that metals each insusceptible of Ingredients.
magnetism, when united strongly display this property.
Such is the discovery of Mr. Fr. Heusler, of Dillenburg, near Wiesbaden. He
noticed one day that an alloy of manganese, tin, and copper adhered to a
tool which he had accidentally magnetized. In the course of experiments
Mr. Heusler found that carbon, silicon, and phosphorus did not confer
magnetism; while arsenic, antimony, and bismuth did so, all three metals
being diamagnetic, that is, placing themselves at right angles to a common
steel magnet above which they are freely suspended. An alloy of
remarkable magnetic strength was composed of copper 61.5 per cent.,
manganese 23.5 per cent., and aluminium 15 per cent. This alloy is brittle
and considerable changes of temperature but slightly affect its magnetism.
When a little lead is added magnetism disappears between 60° and 70° C.
This alloy therefore is magnetic when placed in cold water; when the water
is heated the magnetism disappears before the water boils, only to reappear
when the water cools. The main interest of these discoveries is that the new
alloys bridge the gap betwixt magnetic and diamagnetic bodies, that is, they
join the iron, nickel, and cobalt group, which place themselves along the
line of a magnetic field, with the diamagnetic elements, bismuth, antimony,
zinc, tin, lead, silver, and arsenic, which place themselves at right angles to

the lines of a magnetic field. We have been accustomed to suppose that
magnetism is a property possessed by only a few elements; these alloys
show us that magnetism may arise as a result of grouping atoms, none of
which by itself has any magnetism whatever. Indeed it may be possible to
make an alloy more magnetic than iron, furnishing the electrician with
electro-magnets of new power.
We have briefly glanced at recent progress in the art of Anti-Friction
alloying in so far as it has produced steels of new Alloys.
strength, elasticity, or hardness; new ability to resist
abrasion or high temperatures, new capacity for magnetism, new
indifference to changes of temperature as affecting dimensions. Alloying
has of late years conferred other gifts upon industry, of which one example
may be cited from among many of equal importance. Friction levies so
grievous a tax upon the mechanic and the engineer that they are quick to
seize upon any material for bearings which reduces friction. As the result of
extensive experiments Dr. C. B. Dudley recommends an alloy of tin,
copper, a little phosphorus, with ten to fifteen per cent. of lead. He finds the
loss of metal by wear under uniform conditions diminishes as the lead is
increased and the tin diminished.
We have seen how remarkably the properties of iron are Influence of
affected by minute additions of carbon which may be Minute
assumed to enter into chemical union with the metal. The Admixtures.
properties of other metals may be influenced by minute
quantities of added elements, although in quantities so small as to preclude
the possibility of their forming ordinary chemical compounds. It by no
means follows, however, that the atom of an added element does not exert a
direct influence. In Professor Roberts-Austen’s laboratory, in London, two
ladles were filled with exceptionally pure bismuth; into one ladle a tiny
fragment of tellurium was placed. The ladles were poured each into a
separate mold, and when the metal became cold it was fractured by a
hammer. The bismuth to which the tellurium was added had become
minutely crystalline; while that which remained pure had crystallized in
broad mirror-like planes. One reflected light as a mirror; the other,
containing the tellurium, scattered the light it received. With no guidance
but that of mere inspection, one would have said that the two substances

were distinct elements, and yet the only difference was that one contained
1⁄2000 part of tellurium and the other no tellurium at all.

Submarine telegraphy presents us with a case as striking: were its copper
wire to contain but one-thousandth part of bismuth, the line would be so
much reduced in conductivity as to be commercially worthless: quite as
harmful are mixtures of antimony. In coining, the addition to gold of one
five-hundredth part by weight of bismuth produces an alloy which crumbles
under the die and refuses to take an impression. In the manufacture of such
dies it is necessary to employ a steel containing 0.8 to 1 per cent. of carbon
and no manganese. It is usual, says Professor Roberts-Austen, to water-
harden and temper it to a straw color, and a really good die will strike
40,000 coins without being fractured or deformed, but if the steel contains
0.1 per cent. too much carbon, it would not strike 100 pieces without
cracking, and if it contained 0.2 per cent. too little carbon, it would
probably be hopelessly distorted and its engraved surface destroyed in the
attempt to strike a single coin. As in coining so in steam-engineering. A
little arsenic added to copper improves it for the fire-boxes of locomotives.
Boilers of old, formed of copper slightly admixed with sulphur, lasted
longer than modern boilers built of copper free from sulphur. Antimony
behaves like arsenic, and in due proportion strengthens copper; bismuth, on
the contrary, weakens copper, and a perceptible effect is wrought by a mere
trace. Nickel is made malleable by adding extremely small quantities of
phosphorus, magnesium, or zinc.

BOOKS ON IRON AND STEEL

Chosen and annotated by Professor Bradley Stoughton, School of Mines,
Columbia University, New York. (Graduated Yale University, 1893, as Ph.B. In 1896
Assistant in Mining and Metallurgy at Massachusetts Institute of Technology, Boston, where he
received the degree of B.S. In 1898-99, metallurgist of South Works. Illinois Steel Co., South
Chicago. Superintendent in 1900 of steel foundry, Briggs-Seabury Gun and Ammunition Co., Derby,
Conn. Manager of Bessemer plant, Benjamin Atha & Co., Newark, N. J., in 1901. Instructor in
metallurgy, Columbia University, 1902-03. Next year became Adjunct Professor of Metallurgy,
Columbia University and, as consulting metallurgist, entered the firm of Howe & Stoughton, New
York.)

Bale, George R. Modern Foundry Practice. Part I, 1902. Part II, 1906. London, Technical Publishing
Co. 3s. 6d. each.

An admirable work, the only one covering the whole field. The author thoroughly understands his
subject, and writes most intelligibly. The principles underlying every detail of practice are clearly
explained.
Part I deals with foundry equipment, materials used, furnaces and processes, describes blowers,
ladles, cranes, hoists, cupola, air furnaces, drying ovens, dry and green sand, the manufacture of
chilled castings and malleable iron castings.
Part II takes up machine molding, physical properties, the effects produced by various
ingredients, the principles of mixing irons, cleaning castings. Costs are considered in conclusion.

Bell, Sir Isaac Lowthian. Principles of the Manufacture of Iron and Steel. London, George
Routledge & Sons, 1884. 722 pp. 21s.
A classic. Like “Chemical Phenomena of Iron Smelting,” by the same author, now out of print
and rare, it will never be replaced by a new book in the metallurgist’s library, although somewhat out
of date. Deals with principles ever important, while our knowledge of them increases constantly.
Begins with a brief history, then passes to the direct processes for the production of iron and steel.
Then follow sections on the fundamental principles of blast furnace operation, and a study of the
refining of pig-iron, or, in other words, the principles of the conversion of pig-iron into wrought iron
and steel. For recent metallurgical practice, some later book is to be preferred.
Campbell, Harry Huse. Manufacture and Properties of Iron and Steel. 2d edition. New York,
Engineering and Mining Journal, 1903. 839 pp. $5.00.
Mr. Campbell is a careful and deep thinker. He is well known as the successful manager of a large
and important steel works. Out of abundant knowledge, gathered in long experience and study, he
gives in this book much valuable information. Details of the various furnaces and their operations are
frequently lacking, but as a comparative study of leading methods of steel-making, and of the
commercial conditions involved, this work has no equal.
Harford, F. W. Metallurgy of Steel. With a section on the Mechanical treatment of Steel, by F. W.
Hall. Revised edition. London, Charles Griffin & Co., 1905. 792 pp. 25s.
This exhaustive treatise is the best of its kind. Abounds with valuable information on furnaces
and their working, on the effects of different impurities in steel. On the shaping of steel mechanically
it is the only complete treatise. This work deals, however, chiefly with English practice, while
American practice is larger and more progressive.
Howe, Henry M. Iron, Steel and Other Alloys. 2d edition, slightly revised. Boston, A. Sauveur, 1906.
18+495 pp. $5.00.
The best and most complete work on the modern theory of the constitution of steel by the highest
living authority. Can be readily understood by any one having a slight knowledge of chemistry. In
addition to the study of iron and steel as metals, brief but satisfactory chapters in manufacture are
included.
Howe, Henry M. Metallurgy of Steel. Vol. I. 4th edition. New York, Engineering and Mining
Journal, 1890. 385 pp. $10.00.
Still recognized the world over as the standard authority; every book written on its theme since
1890 builds upon this work as the source of highest reference. Devoted chiefly to the effects of
different impurities, and of treatment, on steel. The crucible and Bessemer processes are described at
some length. Not a work for general readers.
Mellor, J. W. Crystallization of Iron and Steel: an Introduction to the Study of Metallography.
London and New York, Longmans, Green & Co., 1905. 154 pp. 5s. $1.60.
Reprinted lectures giving an excellent popular account of the constitution and nature of cast iron
and steel. Includes right and wrong methods of annealing, hardening and tempering steel, and their

microscopic examination. The information is presented in a terse and attractive style. Any reader of a
scientific turn will find profit in this book.
Sexton, A. Humboldt. Outline of the Metallurgy of Iron and Steel. Manchester, Scientific Publishing
Co., 1902. 16s.
The best, because most recent of the good elementary text-books on iron and steel. It is behind
the times in regard to American practice, but contains a great deal of important information, clearly
expressed. Covers iron ores, their physics and chemistry, construction and working of the blast
furnace, foundry practice, puddling, forging, the Bessemer, open hearth and crucible processes,
special steels, the testing of steel and protection from corrosion. Its sketch of the structure and heat
treatment or iron and steel is very incomplete.
Swank, James M. Short History of the Manufacture of Iron in all ages, particularly in the United
States from 1585 to 1885. 2d edition. Philadelphia, American Iron and Steel Association, 1894.
428 pp. $5.00.
The best historical account of iron and steel manufacture, written in an interesting manner. So
carefully systematized that the history of any branch of the subject may be studied independently.
Swank, James M. Directory of the Iron and Steel Works in the United States and Canada. Embracing
a full description of the blast furnaces, rolling mills, steel works, tin plate and terne plate works,
forges and bloomaries in the United States; also classified lists of the wire rod mills, structural
mills, plate sheet and skelp mills, Bessemer steel works, open hearth steel works, and crucible
steel works. 16th edition. Philadelphia, American Iron and Steel Association, 1904. $10.00.
A Supplement to this directory contains a classified list of leading consumers of iron and steel in
the United States, corrected to January, 1903. 196 pp. $5.00.
The Penton Publishing Co., Cleveland, Ohio, publish a list of the iron foundries in the United
States and Canada, mentioning plants not listed by Mr. Swank, 1906. $10.00.

Turner, Thomas. Metallurgy of Iron and Steel. Edited by Prof. W. C. Roberts-Austen. Vol. I,
Metallurgy of Iron. London, Charles Griffin & Co., 1895. 367 pp. 16s.
If but one book is to be chosen, this is the best on ores, construction and working blast furnaces,
the properties of cast iron, the manufacture and properties of wrought iron. It also has valuable
chapters on foundry practice, the history of iron, blast furnace fuels, forging and rolling, and the
corrosion of iron and steel.
Woodworth, Joseph V. Hardening, Tempering, Annealing and Forging of Steel: a treatise on the
practical treatment and working of high and low grade steel. New York, Norman W. Henley &
Co., 1903. 288 pp. $2.50.
Treats of the selection and identification of steel, the most modern and approved processes of
heating, hardening, tempering, annealing and forging, the use of gas blast forges, heating machines
and furnaces, the annealing and manufacture of malleable iron, the treatment and use of self-
hardening steel, with special reference to case-hardening processes, the hardening and tempering of
milling cutters and press tools, the use of machinery steel for cutting tools, forging and welding high
grade steel forgings in America, forging hollow shafts, drop-forging, and grinding processes for tools
and machine parts.
It is almost impossible to say which is the best book on the practice treated in this book. It has
been chosen because it contains much valuable information which has the rare quality of not only
being useful in the shop, but of being accompanied by the reasons involved. Copiously illustrated.
Many useful tables. For one looking for general knowledge it will be found serviceable. For the
seeker who wishes special data no single book will suffice.

Journal of the Iron and Steel Institute. Edited by Bennett H. Brough. London. Published by the
Institute. Semiannual. Each number 16 shillings; mailed by Lemcke & Buechner, 11 E. 17th St.,
New York. $4.50.
Contains many articles of importance, and abstracts of a large part of the current literature of iron
and steel. Thus almost every metallurgist who begins the study of a new subject uses this Journal; he
finds it a guide to the latest information which has not yet found its way into reference and text
books.
Revue de Metallurgie. Edited by Henri Le Chatelier. Paris. Monthly. Per annum, 40 francs; mailed
by Lemcke & Buechner, 11 E. 17th St., New York. $10.00.
Most valuable for recent literature on the constitution of iron and steel and their alloys. Contains
bibliographies of works on these subjects.

CHAPTER XIV
PROPERTIES—Continued

Glass of new and most useful qualities . . . Metals plastic under pressure . . . Non-conductors of heat
. . . Norwegian cooking box . . . Aladdin oven . . . Matter seems to remember . . . Feeble influences
become strong in time.

As in the case of the aluminium bronzes and nickel steels, Jena Glass.
alloys of the utmost value have been formed by introducing
new ingredients, often in little more than traces, or by
modifying but slightly the proportions in which ingredients long familiar
have been mingled together. An equal gain has followed upon varying anew
the composition of glass. For centuries the only materials added to sand for
its melting pot were silicic acid, potash, soda, lead-oxide, and lime. As
optical research grew more exacting the question arose, Will new
ingredients give us lenses of better qualities? First of all came the demand
for glasses which combined in lenses would yield images in the telescope
and microscope free from color. In a simple lens, such as that of an ordinary
reading glass, we can readily observe the production of color by a common
beam of light. The rays of different colors, which make up white light, are
refrangible in different degrees, so that while the violet rays come to a focus
near the lens, the red rays have their focus farther off; the images, therefore,
instead of being sharply defined, are surrounded by faint colored rings. In a
telescope or microscope a simple lens would be of no value from the
indistinctness of its images. To correct this dispersion of color a second lens
of opposite action is placed behind the first, that is, a crown-glass lens is
added to a flint-glass lens. (See cut, p. 255.) This remedy is not quite perfect
for the reason that the distribution of the spectrum from violet to red varies
with each kind of glass, and in such a way that through failure of
correspondence, color to color, in a compound lens, variegated fringes of
light, though faint, are perceptible, much to the annoyance of the
microscopist, the astronomer, and the photographer.
With a view to producing glasses which united in compound lenses should
be color free, Rev. Vernon Harcourt, an English clergyman, in 1834 began

experiments which he continued for twenty-five years. By using boron and
titanium in addition to ordinary ingredients of glass, he produced lenses less
troubled by color than any that had before been made. His labors, only in
part successful, were in 1881 followed by those of Professor Ernst Abbe
and Dr. Otto Schott at Jena. With resources provided by the Government of
Prussia, these investigators were able to do more for the science and art of
glass-making than all the workers who stood between them and the first
melters of sand and soda. They immensely diversified the ingredients
employed, carefully noting the behavior of each new glass, how much light
it absorbed, how it behaved in damp air, what strength it had, how it
retained its original qualities during months of keeping, and in particular
how variously colored rays were distributed throughout its field of
dispersion. As in the blending of new alloys it was found that many of these
novel combinations were useless. Of the scores of new glasses produced
some were extremely brittle, others were easily tarnished by air, or so soft
as to refuse to be shaped as prisms or ground as lenses. A more systematic
plan of experiment was therefore adopted: for the production of new glasses
there were by degrees separately introduced in varied quantities, carefully
measured, boron, phosphorus, lithium, magnesium, zinc, cadmium, barium,
strontium, aluminium, berylium, iron, manganese, cerium, didymium,
erbium, silver, mercury, thallium, bismuth, antimony, arsenic, molybdenum,
niobium, tungsten, tin, titanium, fluorine, uranium. An early and cardinal
discovery was that the relation between refraction and dispersion may be
varied almost at will. For example, boron lengthens the red end of the
spectrum relatively to the blue; while fluorine, potassium, and sodium have
the opposite effect. With the distribution of the diverse hues of the spectrum
thus brought under control, there were produced glasses which, when united
as compound lenses, were almost perfectly color-free, rendering images
with a new sharpness of definition. Yet more: in their unceasing round of
experiments Professor Abbe and Dr. Schott came upon glass so little
absorbent of light that combinations of much thickness intercepted only a
small fraction of a beam; they were indeed almost perfectly transparent.
This achievement is of great importance to the photographer, whose planar
combination of six lenses may be four inches in thickness. At Jena the
researchers are endeavoring to perfect another gift for the camera: they seek
to produce glasses each transmitting but one color, for service in color-
photography.

To microscopy they have recently given lenses which completely transmit
ultra-violet rays so as to photograph the diffraction discs of objects, such as
gold particles in colloidal solutions, otherwise invisible, because below the
resolving power of the most powerful microscope. It is estimated that with
this new aid an object but 1⁄250,000,000 of a millimeter in length may indirectly
be brought to view.
One ancient art, that of annealing glass, Professor Abbe and Dr. Schott
greatly improved, eliminating from their products the stresses which distort
an image. By means of an automatic heat-regulator, the temperature of a
batch of glass could be kept steadily for any desired period at any point
between 350° and 477° C.; or allowed to fall uniformly at any prescribed
rate. The glass was usually contained in a very thick cylindrical copper
vessel, on which played a large gas flame. The highest temperature found
necessary to banish stress, that is, to cause softening to begin, was 465° C.
The lowest temperature required to ensure complete hardening was about
370° C. Thus the temperatures of solidification all lie between 370° and
465°. This fall of 95° was spread over an interval of four weeks, instead of a
few days as formerly, with the result that stress was banished utterly.

Photograph by Bräunlich & Tesch.
THE LATE PROFESSOR ERNEST ABBE, OF JENA.

A practical example of the benefits gained in the properties of Jena glass is
exhibited by its use in measuring heat. A thermometer of common glass
when first manufactured may tell the truth, and in a month or two may vary
from truth so much as to be worthless. The reason is that the dimensions of
the glass slowly change day by day, as in a less degree do those of many
alloys. It was one of the aims of the Jena laboratory to produce a glass
which should remain constant in its dimensions while exposed to varying

temperatures, so that, made into thermometers, it would be thoroughly
trustworthy. Here, too, success was attained, so that thermometers of Jena
glass are found to be reliable as are no instruments of ordinary glass. This
product is available for astronomical lenses, otherwise liable to serious
changes of form as exposed successively to warmth and cold.
Heat was to be staunchly withstood not only in moderate variations, but in
extreme degrees. From time immemorial heat suddenly applied to glass has
riven it in pieces. Could art dismiss this ancient fault? To-day a beaker from
Jena may be filled with ice and placed with safety on a gas flame. In its
many varieties this glass furnishes the chemist with clean, transparent and
untarnishing vessels for the delicate tasks of the laboratory, all of singular
indifference to heat and cold. Yet again. Special kinds of this glass in
chemical uses are attacked by cold or hot corrosive liquids only one-twelfth
to one-fourth as much as good Bohemian glass, the next best material.
Not only to heat but to light Jena glass renders a service. Glass of ordinary
kinds when used for the tubes of a Hewitt mercury-vapor lamp, absorbs a
considerable part of the ultra-violet rays upon which photography chiefly
depends. A Jena glass free from this fault is formed into Uviol lamps of
great value in taking photographs, photo-copying, and photo-engraving.
These lamps are also employed in ascertaining the comparative stability of
inks and artificial dyes; so intense is their action that brief periods suffice
for the tests. Uviol rays severely irritate the eyes and skin; they may prove
useful in treating skin diseases. They moreover quickly destroy germs. In
all these activities reminding us of radium.
Thus by a bold departure from traditional methods in glass-making, the eye
receives aid from lenses more powerful and more nearly true than ever
before swept the canopy of heaven, or peered into the structure of minutest
life. Meanwhile instruments of measurement take on a new accuracy and
retain it as long as they last. All this while a material invaluable for its
transparency is redeemed from brittleness and corrodibility, and given a
strength all but metallic; at the same time transmitting light with none of the
usual subtraction from its beams.

Bliss forming die. A, bed plate. B, blank-holder. C, drawing
punch. D, push-out plate. O, P, annular pressure surfaces.

Bliss process of shell making.

From glass let us now turn to metals. It is their tenacity
Power Presses in
that chiefly gives them value; this tenacity is usually Metal Working.
accompanied by a hardness which disposes us to regard
nickel, for example, as of a solidity quite unyielding. But the coins in our
pockets prove that under the pressure of minting machinery they are as
impressible as wax. In molds and dies, each the counterpart of the other,
brass, bronze, iron, steel, and tin-plate take desired forms as readily as if

paste. Solid though these metals appear they yield under severe stress with a
semi-fluid quality. We have long had stamped kitchen ware, baking pans,
and the like; the principle of their manufacture has of late years been
extended to ware of more importance. Bliss power presses are to-day
turning out hundreds of articles which until recently were either slowly
hammered or spun into form, pieced with solder, or shaped by the gear
cutter or the milling machine. These presses furnish the United States Navy
with sharp-pointed projectiles, some of them so large as to demand a
million pounds pressure for their production; they make strong seamless
drawn bottles, cylindrical tanks for compressed air and other gases, and
cream separators able to withstand the bursting tendency of extremely swift
rotation.

Mandolin pressed in aluminium.

Pressed Seamless pitcher.

Barrel of pressed steel.

Presses less powerful produce scores of parts for sewing machines,
typewriters, cash registers, bicycles, and so on; or, at a blow, strike out a
gong from a disc of bronze. Presses of another kind stamp out cans in great
variety, and even a mandolin frame in all its irregular curves. Tubs are
quickly pressed from sheets of metal; a pair of such tubs, tightly joined at
their rims by a double seam, form a barrel impervious to oil or other liquid,
and hence preferable to a wooden barrel. A press operated by a double
crank may be arranged to supersede the forging of hammers, axes, and
mattocks. Another press at a blow cuts out the front for a steel range. Still
another press invades the foundry, producing excellent gear wheels for
trolley cars, not weakened by being cut from a casting across the grain of
the metal. Sometimes the article manufactured requires a series of
operations, as in the case of a kettle cover with its knob. At the Lalance &
Grosjean factory, Woodhaven, New York, a Bliss press makes such covers
in a single continuous round. Another press treats soft alloys, so that a disc
one inch in diameter when hit by a plunger is forced into the shape of a tube
suitable to hold paint or oil.
In large manufactures as in small the hydraulic forge has wrought a quiet
revolution. If a steel freight car were produced by planing, turning, slotting
and similar machines, it would be much heavier and dearer than as turned
out to-day from ingeniously fashioned dies under severe pressure. Its
girders are molded of the same strength throughout with no waste of
material, and without rivets; corner pieces are avoided; stiffeners are built
up from the plates themselves through the introduction of ridges and
depressions: and in a structure having the fewest possible parts, uniform

strength is attained because dimensions everywhere may freely depart from
uniformity.

Range front pressed from sheet steel.

Pressed paint tube and cover.

In a vast manufactory of steel cars, of steel structural
Non-Conductors
forms, steam has to be conveyed long distances from the of Heat.
boilers. Here, as in similar huge establishments, or in the
heating of towns and cities from central stations, it is desirable to lose as
little heat as possible by the way, for undue waste means enormous inroads
upon profits. There are other reasons for wishing to keep heat within a
steam pipe; much damage may be done to fruit, flour and other merchandise
unduly warmed. Furthermore there is a risk of setting fire to woodwork,
paper, cotton and the like; it has been observed that after a month’s
exposure to heat from steampipes, wood takes fire at a temperature which at
first would not have led to ignition, because then the wood contained a little
moisture. To guard against loss and danger it has long been the practice to
cover steampipes with jackets of non-conducting material, such as mineral-
wool,—furnace-slag blown into short glassy fibres by a sharp blast of air.

Felt, loosely folded, also serves well. Many advertised claims for asbestos
are not well founded; this mineral is incombustible and is therefore useful
in thick curtains to separate a stage from the auditorium of a theatre. But it
is a fairly good conductor, and for steampipes should be used as a direct
covering of the metal simply to keep an outer and much thicker coat of felt
from being charred. Whatever the material chiefly employed, one point is
clearly brought out by experiment, namely, that the air detained by the
fibres of a covering greatly aids in obstructing the passage of heat. Hence it
is well to keep the materials from becoming compacted together, as do
ashes when moistened. Asbestos fibres, which are smooth and glassy, do
not take hold of air as do cork and wool.
Professor J. M. Ordway, of the Massachusetts Institute of Technology,
Boston, tells us that non-conductors should be of materials that are
abundant and cheap; clean and inodorous; light and easy to apply; not liable
to become compacted by jarring or to change by long keeping; not
attractive to insects or mice; not likely to scorch, char or ignite at the long-
continued highest temperature to which they may be exposed; not liable to
spontaneous combustion when partly soaked in oil; not prone to attract
moisture from the air; not capable of exerting chemical action on the
surfaces they touch. No material combines all these desirable qualities, but
a considerable range of substances fulfil most of the requirements.
Tests of steam-pipe coverings at Sibley College, Cornell University, and at
Michigan University, have resulted as follows:—
Relative Amount
Kind of Covering of Heat
Transmitted
Naked pipe 100.
Two layers asbestos pipe, 1 inch hair felt, canvas cover 15.2
The same, wrapped with manila paper 15.
Two layers asbestos paper, 1 inch hair felt 17.
Hair felt sectional covering, asbestos lined 18.6
One thickness asbestos board 59.4
Four thicknesses asbestos paper 50.3
Two layers asbestos paper 77.7
Wool felt, asbestos lined 23.1
Wool felt with air spaces, asbestos lined 19.7
Wool felt, plaster paris lined 25.9
Asbestos molded, mixed with plaster paris[188] 31.8

Asbestos felted, pure long fibre 20.1
Asbestos and sponge 18.8
Asbestos and wool felt 20.8
Magnesia, molded, applied in plastic condition 22.4
Magnesia, sectional 18.8
Mineral wool, sectional 19.3
Rock wool, fibrous 20.3
Rock wool, felted 20.9
Fossil meal, molded, 3⁄4 inch thick 29.7

In general the thickness of the coverings tested was one inch. Some tests
were made with coverings of different thicknesses, from which it would
appear that the gain in insulating power obtained by increasing the
thickness is very slight compared with the increase in cost.[19]
[19] Rolla C. Carpenter, “Heating and Ventilating Buildings,” p. 229. New York, John
Wiley & Sons, 1905.

Some properties of matter seem to have family ties. Tenacity and
conductivity for heat, as an example, go together; all the tenacious metals as
a group are conducting as well. Conversely, the non-conductors,—felt,
gypsum, and the rest, are structurally weak. If the inventor could lay hands
on a material able to withstand high pressure and, at the same time, carry
off wastefully but little heat, he would build with it cylinders for steam
engines much more economical than those of to-day He would also give
cooking apparatus of all kinds a covering which would conduce to the
health and comfort of the cook, while, at the same time, heat would be
economized to the utmost. One of the advantages of electric heat is that it
can be readily introduced into kettles and chafing dishes surrounded by
excellent non-conductors; the result is an efficiency of about ninety-five per
cent., quite unapproached in the operations of a common stove or range.
The costliness of electric heat forbids the housekeeper
Norwegian
from using much of it. Her main source of heat must Cooking Box.
long continue to be the common fuels. These, however,
thanks to cheap non-conductors, may be used with much more economy
and comfort than of old. Take, for example, the Norwegian cooking box,
steadily gaining favor in Europe and well worthy of popularity in America.
It consists of a box, preferably cubical, made of closely fitted thick boards,
with a lid which fits tightly. Box and lid are thickly lined with felt or
woolen cloth, and filled with hay except where pots are placed. These pots,

filled with the materials for a soup, a stew, a ragout, are brought to a boil on
a fire and then placed within the box, its lid being then fastened down. For
two hours or so the cooking process goes on with no further application of
heat. To be sure the temperature has fallen a little, but it is still high enough
to complete the preparation of a wholesome and palatable dish, with
economy of fuel and labor, without unduly heating the kitchen.

Norwegian cooker.

On the same principle is the Aladdin oven, invented by the Aladdin oven.
late Edward Atkinson of Boston, and manufactured by the
Aladdin Oven Company, Brookline, Mass. It is built of iron,
surrounded with air cell asbestos board, so as to maintain a cooking
temperature of 400° Fahr. with little fuel or attention. Its drop door when
open forms a shelf, when closed it is fastened by a brass eccentric catch,
ensuring tightness; its wooden stand has an iron top to hold the oven firmly
in place. This apparatus cooks a wide range of dishes admirably, retaining
the natural flavors of meats, fish, vegetables and fruits as ordinary excessive
temperatures never do. Mr. Atkinson wrote “The Science of Nutrition,”
which sets forth the construction and uses of this oven.[20]
[20] Published by Damrell & Upham, Boston. $1.00.

Aladdin Oven.

Every property of matter seems universal. The best non- Matter Impressed
conductor of heat transmits a little heat; the best by Its History.
conductor is by no means perfect: the two classes of
substances are joined by materials which gradually approach one end of the
scale or the other. Nothing is so hard but that it may be indented or
engraved, and where neither a blow nor severe pressure is employed, we
may have, as in the photographic plate, an impression which is chemical
instead of mechanical, displaying itself to the eye only when treated with a
suitable developer. A bar of steel hammered on an anvil is changed in
properties; as it becomes closer in texture its tenacity is increased. When
that bar takes its place in a structure, the work it has to do, the shocks it
bears, equally tell upon its fibres. Stresses and strains leave their effects
upon the stoutest machines, engines, bridges; they are never the same
afterward as before, and usually their experience does them harm. Says an
eminent engineer, Mr. W. Anderson: “The constant recurrence of stresses,
even those within the elastic limit, causes changes in the arrangement of the
particles which slowly alter their properties. In this way pieces of
machinery, which theoretically were abundantly strong for the work they

had to do, have after a time failed. The effect is intensified if the stress is
suddenly applied, as in the case of armor plate, or in the wheels of a
locomotive. . . . When considerable masses of metal have been forged, or
severely pressed while heated, the subsequent cooling of the mass imposes
restrictions on the free movement of some if not all the particles, hence
internal stresses are developed which slowly assert themselves and often
cause unexpected failures. In the manufacture of dies for coinage, of chilled
rollers, of shot and shell hardened in an unequal manner, spontaneous
fractures take place without apparent cause, through constrained molecular
motion of the inner particles gradually extending the motion of the outer
ones until a break occurs.”
Sir Benjamin Baker says:—“Many engineers ignore the fact that a bar of
iron may be broken in two ways—by a single application of a heavy stress,
or by the repeated application of a comparatively light stress. An athlete’s
muscles have often been likened to a bar of iron, but if ‘fatigue’ be in
question, the simile is very wide of the truth. Intermittent action, the
alternative pull and thrust of the rower, or of the laborer turning a winch, is
what the muscle likes and the bar abhors. A long time ago Braithwaite
correctly attributed the failure of girders, carrying a large brewery vat, to
the vessel being sometimes full and sometimes empty, the repeated
deflection, although imperceptibly slow and free from vibration,
deteriorating the metal, until in the course of years it broke. These girders
were of cast iron, but it was equally well known that wrought iron was
similarly affected, for Nasmyth afterward called attention to the fact that the
alternate strain in axles rendered them weak and brittle, and suggested
annealing as a remedy, having found that an axle which would snap with
one blow when worn, would bear eighteen blows when new or just after
annealing. We know that the toughest wire can be broken if bent backward
and forward at a sharp angle; perhaps only to locomotive and marine
engineers does it appear that the same result will follow in time even when
the bending is so slight as to be unseen by the eye. A locomotive crank-axle
bends but 1⁄34 inch, and a straight driving axle but 1⁄64, under the heaviest
bending stresses to which they are exposed, and yet their life is limited.
Experience proves that a very moderate stress alternating from tension to
compression, if repeated about a hundred million times, will cause fracture
as surely as bending to a sharp angle repeated a few hundred times.”

Hence an axle, or other structure, should be tested by just such stresses as it
is to withstand in practice. A steel bar may satisfactorily pass a tensile test
applied in one direction, only to break down disastrously under alternating
stresses each less severe.
That matter virtually remembers its impressions is plain
Magnetization.
when we study magnetism. Steel when magnetized for the
first time does not behave as when magnetized afterward. It
is as if magnetism at its first onset threw aside barriers which never again
stood in its way. If the steel is to be brought to its original state it must be
melted and recast, or raised to a white heat for a long time. In quite other
fields of channeled motion we remark that violins take on a richer sonority
with age; their fibres, under the player’s hand, seem to fall into such lines as
better lend themselves to musical expression.
In 1878 the late Professor Alfred M. Mayer of the Stevens Institute of
Technology, Hoboken, New Jersey, published a series of remarkable
experiments in the “American Journal of Science.” He there told and
pictured how he had magnetized several small steel needles, thrust through
bits of cork set afloat in water, the south pole of each needle being upward.
As the needles repelled each other, or had their repulsion somewhat
overcome by a large magnet held above them with its north pole downward,
the needles disposed themselves symmetrically in outlines of great interest,
which varied, of course, with the number of needles afloat at any one time.
Three needles formed an equilateral triangle, four made up a square, five
disposed themselves either as a pentagon or as a square with one magnet at
its centre, and so on in a series of regular combinations, all suggesting that
magnetic forces may underlie the structure of crystals.

Mayer’s floating magnets.

One of the remarkable attributes of a crystal is its ability The Crystal
to grow and act as a unit, as if it had a life of its own, Foreshadows the
despite the evident variety and great number of its parts. Plant.
Take a crystal of alum, break off a corner and then
immerse the broken mass in its mother liquor; at once the crystal will repair
itself, new molecules building themselves into its structure as if they knew
where to go. This unity of effect may be observed during a northern winter
on a scale much more striking. In cold weather on a large sheet of plate
glass exposed as a window, a frost pattern will extend itself as if a tree,
beautiful branches spreading themselves from a main stem which may be
seven feet in height. It is altogether probable that polar forces, such as we
observe in the magnet, are here at work. Their harmony of effect, in spaces
comparatively vast, is astonishing. Forces of allied character rise to a plane
yet higher in vegetation, culminating in the magnificent sequoia of
California, whose life, measured by thousands of years, goes back almost to
the dawn of human civilization. The union of tools, levers, wheels, as an

organized machine; the co-ordination in research of the parts to be played
by observers, recorders, depicters, generalizers; the regimentation of
soldiers, so that all march, advance and fire as one man under the control of
a single will, is prefigured in the forces which make a unit of every crystal
of saltpetre in a soldier’s cartridge-box. Of all the characteristics of matter
none is more pervasive and more marvelous than its ability to form a unit
which moves and acts as if no part were separable from any other, while
manifesting a highly complicated structure, with functions at once intricate
and co-ordinate.

A B C
Alum crystal. After a part has been Restored by immersion
broken off. in alum solution.
From photographs by Herr Hugo Schmidt, Hackley School, Tarrytown, N. Y.

Qualities of matter, much more simple, may now engage During Long
our attention. First, then, let us note how minute Periods Minute
influences, acting for long stretches of time, may change Influences Become
Telling.
the qualities of metals and rocks. Forces, too slight for
measurement as yet, are known in the course of a year or
two to affect steel at times favorably, at other times unfavorably. The
highest grades of tool-steel are improved by being kept in stock for a
considerable time, the longer the better. It seems that bayonets, swords, and
guns are liable to changes which may account for failure under sudden
thrust or strain. Gauges of tool steel, which are required to be hard in the
extreme, are finished to their standard sizes a year or two after the
hardening process. Slow molecular changes register themselves in altered
dimensions. In the Bureau of Standards at Washington are a yard in steel
and a yard in brass, at first identical in length; after twenty years they were
found to vary by the 1⁄5000 of an inch. Take another case, familiar enough to

the railroad engineer: in a mine, or a tunnel, the roof or wall may tumble
down a month or more after a blasting. The stone which fell immediately
upon the explosion was far from representing all the work done by the
dynamite. A stress was set up in large areas of rock and this at last,
beginning in slight cracks, overcame the cohesion of masses of huge extent.

Iron tube enclosing marble Marble before deformation
before and after deformation. and after.

Properties undergo change during the simple flight of time: a parallel
diversity is worthy of remark. A substance exhibits quite diverse qualities
according to whether the action upon it is slow or speedy. A paraffine
candle protruding horizontally half way out of a box, during a New York
summer will at last point directly downward, for all its brittleness. If
shoemaker’s wax is struck a sudden blow, it breaks into bits as might a pane
of window glass. But place leaden balls on the surface of this same wax and
in the course of ten or twelve weeks you will find them sunk to the bottom
of the mass. When sharply smitten, the wax is rigid and brittle; to a long
continued, moderate pressure the wax proves plastic, semi-fluid almost. All
this is repeated when stone is subjected to severe pressure for as long a
period as two months. At McGill University, Montreal, a small cylinder of
marble thus treated by Professor Frank D. Adams became of bulging form,
without fracture, but with a reduction in tensile strength of one-half. When
the pressure was applied during but ninety minutes the tensile strength of
the resulting mass was but one-third that presented by the original marble;
when the experiment occupied but ten minutes the tenacity fell to somewhat
less than one-fourth its first degree. These researches shed light on the

stratifications of rocks often folded under extreme pressure as if rubber or
paste.
Take another and quite different example of how variations in time bring
about wide contrasts of result: a rubber ball thrown in play at a wall
rebounds; send it forth from a cannon, with a hundred-fold this velocity,
and it pierces the wall as might a shot of steel.

CHAPTER XV
PROPERTIES—Continued. RADIO-ACTIVITY

Properties most evident are studied first . . . Then those hidden from cursory view . . . Radio-activity
revealed by the electrician . . . A property which may be universal and of the highest import . . . Its
study brings us near to ultimate explanations . . . Faraday’s prophetic views.

roperties age after age have become more and more intimately known.
P At first the savage took account solely of the obvious strength of an
oak, the sharpness of a flint, the pliability of a sinew. With the first
kindling of fire he discovered a new round of properties in things long
familiar. All kinds of wood, especially when dry, were found combustible,
so were straw and twigs, as well as the fat of birds, the oil of fish. Then it
was noticed that the ground beneath a fire remained unburnt and grew firm
and hard, so that its clay or mud might be used for rude furnaces and ovens.
Soon come experiments as to the coverings which maintain coals at red
heat, ashes proving the readiest and best.
A century ago the mastery of electricity began to unfold a new knowledge
of properties, so wide and intimate as to recall the immense expansion of
such knowledge that long before had followed upon the kindling of fire.
The successors of Volta, as they reproduced his crown of cups, asked, What
metals dissolved in what liquids will give us an electric current at least
outlay? Then followed the further question, What metals drawn into wire
will bear currents afar with least loss? With the invention of the electro-
magnet came another query, What kinds of iron are most swiftly and largely
magnetized by a current; and when the current ceases, which of them loses
its magnetism in the shortest time? Plainly enough the electrician regards
copper, zinc, iron, steel, acids, alkalis from a new point of view; he
discovers in them properties which until his advent had been utterly
ignored.
Among the properties of matter revealed by electricity none are more
striking than those displayed in tubes containing highly rarified gases. The
study of their phenomena has led to discoveries which bring us within view
of an ultimate explanation of properties, an understanding of how matter is

atomically built. All this began simply enough as Plucker, in 1859, sent an
electric discharge through a tube fairly well exhausted, producing singular
bands of color. Geissler, afterward using tubes more exhausted, produced
bands of still higher variegation. In 1875 Professor William Crookes
devised the all but vacuous tube which bears his name, through which he
sent electric pulses from a cathode pole, revealing what he called “radiant
matter,” as borne in a beam of cathode rays, as much more tenuous than
ordinary gases as these are more rare than liquids. In 1894 Professor Philipp
Lenard observed that cathode rays passed through a thin plate of
aluminium, much as daylight takes its way through a film of translucent
marble. Next year came the epoch-making discovery of Professor Conrad
Wilhelm Röntgen that cathode rays consist in part of X-rays which readily
pass through human flesh, so as to cast shadows of bones upon a
photographic plate. Cathode rays make air a fairly good conductor of
electricity, while ordinary air is non-conducting in an extreme degree. This
singular power is also possessed by the ultra-violet rays of sunshine, as
readily shown by an electroscope. In 1897 Professor Joseph J. Thomson, of
Cambridge University, demonstrated that cathode rays are made up of
corpuscles, or electrons, about one-thousandth part the size of a hydrogen
atom, and bearing a charge of negative electricity. Such electrons form a
small part of every chemical atom, the remainder of which is, of course,
positively electrified. All electrons are alike, however various the
“elements” whence they are derived; as the most minute masses known to
science they may be among the primal units of all matter.
France, as well as Germany and England, was to take a leading part in
furthering the study of radio-activity. In Paris the famous Becquerel family
had for three generations devoted themselves to studying phosphorescence.
Henri Becquerel, third of the line, said, “I wonder if a phosphorescent
substance, such as zinc sulphide, would be excited by X-rays.” He tried the
experiment, causing the sulphide to glow with new vigor. From that
moment proofs have accumulated that the rays of common
phosphorescence such as are emitted by matches, decaying wood and fish,
are of kin to the cathode rays which the electrician evokes from any
substance whatever when he employs a high-tension current. One day M.
Becquerel came upon a remarkable discovery. He noticed that compounds
of uranium, whether phosphorescent or not, affected a photographic plate

through an opaque covering of black paper, and rendered the adjacent air an
electric conductor. Compounds of thorium, similar to those used for
incandescent mantles, were found to have the same properties. And here
was detected the cause of an annoyance and loss which had long perplexed
photographers. Often they had bestowed sensitive paper or plates within
wrappers of stout paper, or card, or thick wood, secluded in dark cupboards
or drawers. All in vain. At the end of a few weeks or months these carefully
guarded surfaces were as much discolored as if they had been for a few
minutes exposed, here and there, to daylight itself. All the while each
material relied upon as a safeguard had been sending forth a feeble but
constant beam; treachery had lurked in the trusted guardian.
At the suggestion of M. Becquerel, M. and Madame Pierre Curie undertook
a thorough quest for these effects in a wide diversity of substances. They
found that several minerals containing uranium were more radio-active than
that element itself. Pitchblende, for instance, consisting mainly of an oxide
of uranium, was especially energetic as it approached an electroscope,
suggesting the presence of an uncommonly active constituent, thus far not
identified. At the end of a most laborious series of separations they came at
last to a minute quantity of radium chloride displaying extraordinary
properties. Another compound of radium, a bromide, has since been arrived
at: radium by itself has not yet been obtained. In radio-activity radium
chloride surpasses uranium about one-million-fold. Provided with an
electroscope of exquisite sensibility, Professor Ernest Rutherford of McGill
University, Montreal, has discovered seven distinct radiations from radium,
each with characteristics of its own. Directed upon plates of aluminium he
finds its gamma rays to be 100 times more penetrating than its beta rays,
and beta rays 100 times more penetrating than its alpha rays. Each radiation
has qualities as distinct as those of an ordinary chemical element. Beta rays
behave in all respects like cathode rays, so that here a bridge is discerned
betwixt the qualities of radium and the long familiar phenomena of the
Crookes tube.
The substance ranking next in radio-activity to radium is thorium. Professor
Rutherford has observed it throwing off a substance he calls Thorium X;
this radiates strongly for a time, the parent mass not radiating at all.
Gradually Thorium X ceases to radiate and the original thorium resumes an
emission of Thorium X. From Thorium X emanates what seems a gas,

condensible by extreme cold, which attaches itself to adjacent bodies so as
to make them radio-active. This emanation in its turn produces successively
three new and distinct kinds of radiation. Professor Charles Baskerville, of
the College of the City of New York, has separated from thorium two
substances probably elementary, carolinium and berzelium.
Other radio-active substances have each several derivatives: actinium has
nine, uranium has four. As researchers broaden their range of inquiry they
steadily lengthen the list of radio-active substances. Minerals of many
kinds, water from springs, especially those of medicinal value, the leaves of
plants, newly fallen snow, and even common air, are found to be radio-
active, although usually in but a slight degree, so that the doubt may be
expressed, Is the observed effect due to a trace of some highly radio-active
material diffused in something else which is not radio-active at all? Should
it be established that radio-activity is really present in all matter it would be
no other than a parallel to what, at another point in the physical scale,
presents itself as ordinary evaporation.
In a northern winter we may observe in air almost still, Solids are not as
the wasting away of a large block of ice, so that during a Solid as They
week it loses a considerable part of its bulk. The giving Seem.
forth of vapor is evidently not restricted to high or to
ordinary temperatures, but may occur below the freezing point of water. In
1863, Thomas Graham, the eminent Scottish physicist, from many
experiments with metals expressed the opinion that what seems to be a solid
may be also in a minute degree both liquid and gaseous as well.
Confirmation of this view was afforded in 1886 by Professor W. Spring, of
Liege, who formed alloys by strongly compressing their constituents as
powders at ordinary temperatures. It is probable that a slight pervasive
liquidity gave success to the experiment. Professor Roberts-Austen once
observed that an electric-deposit of iron on a clean copper plate adhered so
firmly that when they were severed by force, a film was stripped from the
copper plate and remained on the iron, signifying that the two metals had
penetrated each other at an ordinary temperature. This interpenetration he
found to take place through films of electro-deposited nickel. In a
remarkable round of experiments he also found that at 100° C., a
temperature much below the fusing point of lead, gold as leaf is slightly
diffused through a mass of lead; when the lead is fluid at 550° C., the

proportion of diffused gold is increased 160,000 times. This volatility of the
particles of a heavy metal shows us plainly that virtual evaporation may be
always taking place from metallic surfaces at ordinary temperatures,—a
phenomenon which may be the same in kind as the pouring out of a
perceptible stream of corpuscles under strong electrical excitation. The
analogy goes further, at least in the case of liquids, which exhale a vapor
usually different in composition from the parent body; take, for example, a
solution of sugar in water which sends forth watery vapor only, or observe a
mixture of much water and a little alcohol as it emits a vapor largely
alcoholic and but slightly aqueous.
Here we are reminded of a striking experiment by Every Property
Faraday: exciting an electro-magnet of gigantic May be Universal.
proportions he showed that every substance he brought
near to it was affected in a definite degree. He found iron to be pre-
eminently magnetic, much as Madame Curie has shown radium to be vastly
more radio-active than any other substance. From Faraday’s time to the
present hour the whole trend of investigation has built up the probability
that every known property in some degree exists in all matter whatever.
Copper conducts electricity remarkably well, and gutta percha conducts
remarkably ill; but gutta percha has some little conductivity, or thinner
sheets of it than those now used would suffice to keep within an ocean cable
the throbs which pass between America and Europe. In radio-activity many
substances may be as low in the scale as is gutta percha in the list of electric
conductors; in that case no existing means of detection would make the
property manifest.
While radio-activity may be a universal property of Radium Reveals
matter, to be disclosed more and more as means of Properties
detection are refined and improved, radium compounds Unknown Till
Now.
are to-day in a class quite by themselves. Radium
bromide constantly maintains itself at a temperature of 3°
to 5° C. higher than that of its surroundings, so that every hour it could boil
its own weight of water. Professor Rutherford estimates the life of radium
as 1,800 years, its emanations in breaking up through their successive
stages emitting about three million times as much energy as is given out by
the union of an equal volume of hydrogen and oxygen, mixed in the
proportions which form water, a union accompanied by more heat than that

evolved in any other chemical change. Whence this amazing stream of
energy? It is probable that each radium atom may break into minute parts,
or corpuscles, which, moving at a velocity of 120,000 miles a second or so,
collide so as to cause the observed heat.
From another side the compounds of radium bid us revise the laws of
chemical change as taught up to the close of the nineteenth century. In the
pores of many radio-active minerals may be found that remarkable element,
helium, first detected in the sun by means of the spectroscope, then
afterward discovered in the pores of cleveite, a mineral unearthed in
Norway. Sir William Ramsay and Mr. Frederick Soddy have found helium
in the gases evolved from radium chloride kept as a solid for some months.
The spectrum of helium was at first invisible; it soon appeared and steadily
grew more intense with the lapse of time. “It appears not unlikely,” says
Professor Rutherford, “that many of the so-called chemical elements may
prove to be compounds of helium, or, in other words, that the helium atom
is one of the secondary units with which the heavier atoms are built up.”[21]
[21] Ernest Rutherford “Radio-activity.” Second edition. New York: Macmillan Co.;
Cambridge, England, University Press, 1905.

Photograph by Rice, Montreal.
PROFESSOR ERNEST RUTHERFORD,
McGill University, Montreal.

Already the phenomena of radio-activity, although of puzzling intricacy,
have greatly broadened our conceptions of matter. Where we were wont to
deem it of simple structure, it displays a baffling complexity, as indeed has
long been suggested in so highly diversified a spectrum as that of iron. We
find that radiations from an “element” may consist not only in the
undulations of an ether, but also in an emission of matter as real as the
projection of steam from a boiling pot. Newton believed sunshine to be a

stream of corpuscles: he was wrong with respect to sunlight, his conception
is true of many other kinds of radiation. Until quite lately we looked upon
atoms as indivisible bodies; to-day we have learned that at least some of
them may on occasion divide into many parts, each part moving with a
speed approaching that of light, with energy far exceeding that of any
chemical action we know. In the field of ray-transmission our knowledge
has undergone a like gain in width. Twenty years ago we spoke of the
opacity of lead, the transparency of flint glass, as absolute properties. To-
day we learn that given its accordant ray any substance whatever affords
that ray free passage, as when oak an inch thick transmits pulses from
radium. Yet more: ordinary chemical changes require us to bring one
substance into contact with another; usually we must also apply heat or
electricity to the bodies thus joined; they are always responsive to changes
of temperature. Within the past six years we have become acquainted with
changes incomparably more energetic than those of the most violent
chemical action; many of them proceed with apparent spontaneity from a
substance all by itself. In the case of radium neither extreme cold nor
extreme heat has any perceptible effect upon the radiant stream.
One of the results of investigation in radio-activity is that it shows the
alchemists in their attempts at transmutation to have stood on solid ground.
Says Professor Rutherford: “There can be no doubt that in the radio-
elements we are witnessing the spontaneous transformation of matter, and
that the different products which arise mark the stages or halting places in
the process of transformation, where the atoms are able to exist for a short
time before breaking up into new systems.”
Radio-activity has a vivid interest far beyond the
History of the
laboratories of chemists and physicians. One of the long Universe
standing puzzles of geology has been to explain why the Rewritten in the
temperature of the earth has remained fairly constant Light of Radio-
Activity.
ever since organic life made its appearance. A sister
problem has been the maintenance by the sun of its vast output of heat and
light, age after age, with little or no diminution of intensity. Professor
Rutherford and Mr. Soddy believe that the phenomena of radio-activity may
solve both these problems: an element like helium may furnish a store of
energy vastly greater than that of ordinary chemical action, and much

lengthen the cooling process due to radiation from either the sun or the
earth.
Radio-activity, furthermore, throws new light upon evolution regarded in its
broadest aspects. The corpuscles discovered in 1897 by Professor J. J.
Thomson, as he severed atoms in pieces, are all alike whatever chemical
element may be the parent body. Hence it is argued that we may have here
the primal units of all matter whatever. Sir Norman Lockyer long ago
pointed out that helium and hydrogen predominate in the hottest stars, while
in stars less hot more complex types of matter appear. He argues that these
stars as they successively lose heat show a development of what chemists
call elements. His views are parallel with the suggestion that in the radio-
active corpuscle we make acquaintance with an ultimate element of all
matter, whether observed in a laboratory tube or in the squadrons bright of
the midnight heavens.[22]
[22] Radio-activity and other physical phenomena recently discovered are set forth in “The
New Knowledge,” by Professor Robert Kennedy Duncan, published by A. S. Barnes &
Co., New York, 1905; and “The Recent Development of Physical Science,” by W. C. D.
Whetham, published by John Murray, London, and P. Blakiston, Son & Co., Phila., 1906.

The phenomena of radio-activity revive interest in the prophetic views of
Michael Faraday. In 1816, when he was but twenty-four years of age, he
delivered a lecture at the Royal Institution in London on Radiant Matter. In
the course of his remarks there occurs this passage:—
“If we now conceive a change as far beyond vaporization Faraday’s
as that is above fluidity, and then take into account the Prophetic Views.
proportional increased extent of alteration as the changes
arise, we shall perhaps, if we can form any conception at all, not fall short
of radiant matter; and as in the last conversion many qualities were lost, so
here also many more would disappear.
“It was the opinion of Newton, and of many other distinguished
philosophers, that this conversion was possible, and continually going on in
the processes of nature, and they found that the idea would bear without
injury the applications of mathematical reasoning—as regards heat, for
instance. If assumed, we must also assume the simplicity of matter; for it
would follow that all the variety of substances with which we are
acquainted could be converted into one of three kinds of radiant matter,

which again may differ from each other only in the size of their particles or
their form. The properties of known bodies would then be supposed to arise
from the varied arrangements of their ultimate atoms, and belong to
substances only as long as their compound nature existed; and thus variety
of matter and variety of properties would be found co-essential.”[23]
[23] “Life and Letters of Faraday,” by Bence Jones. Vol. I, p. 216.

Three years later he returned to this theme in another lecture:—
“By the power of heat all solid bodies have been fused into fluids, and there
are very few the conversion of which into gaseous forms is at all doubtful.
In inverting the method, attempts have not been so successful. Many gases
refuse to resign their form, and some fluids have not been frozen. If,
however, we adopt means which depend on the rearrangement of particles,
then these refractory instances disappear, and by combining substances
together we can make them take the solid, fluid, or gaseous form at
pleasure.
“In these observations on the changes of state, I have purposely avoided
mentioning the radiant state of matter, being purely hypothetical, it would
not have been just to the demonstrated parts of the science to weaken the
force of their laws by connecting them with what is undecided. I may now,
however, notice a progression in physical properties accompanying changes
of form, and which is perhaps sufficient to induce, in the inventive and
sanguine philosopher, a considerable belief in the association of the radiant
form with the others in the set of changes I have mentioned.
“As we ascend from the solid to the fluid and gaseous states, physical
properties diminish in number and variety, each state having some of those
which belong to the preceding state. When solids are converted into fluids,
all varieties of hardness and softness are necessarily lost. Crystalline and
other shapes are destroyed. Opacity and color frequently give way to a
colorless transparency, and a general mobility of particles is conferred.
“Passing onward to the gaseous state, still more of the evident characters of
bodies are annihilated. The immense differences in their weights almost
disappear; the remains of difference in color that were left, are lost.
Transparency becomes universal, and they are all elastic. They now form

but one set of substances, and the varieties of density, hardness, opacity,
color, elasticity and form, which render the number of solids and fluids
almost infinite, are now supplied by a few slight variations in weight, and
some unimportant shades of color.
“To those, therefore, who admit the radiant form of matter, no difficulty
exists in the simplicity of the properties it possesses, but rather an argument
in their favor. These persons show you a gradual resignation of properties in
the matter we can appreciate as the matter ascends in the scale of forms, and
they would be surprised if that effect were to cease at the gaseous state.
They point out the greater exertions which nature makes at each step of the
change, and think that, consistently, it ought to be greatest at the passage
from the gaseous to the radiant form.”[24]
[24] “Life and Letters of Faraday,” by Bence Jones. Vol. I, p. 307.

This remarkable deliverance recalls what another great experimental
philosopher, Count Rumford, deduced as by dint of mechanical motion he
melted ice in a closed and insulated receiver. He inferred that the heat thus
generated was not a material substance, as then generally supposed, but
must be in essence motion, for only motion had brought it into existence. As
we follow Faraday’s recital of the successive changes in properties which
follow upon additions of heat, in other words, of mechanical motion, the
inference is irresistible that properties consist in the distinct motions of
masses of definite form and size, these very motions, perhaps, deciding
both the form and size of each mass.

CHAPTER XVI
MEASUREMENT

Methods beginning in rule-of-thumb proceed to the utmost refinement . . . The foot and cubit . . . The
metric system . . . Refined measurement a means of discovery . . . The interferometer measures 1-
5,000,000 inch . . . A light-wave as an unvarying unit of length.

child notices that his bedroom is smaller than the family parlor, that
A to-day is warmer than yesterday was, that iron is much heavier than
wood and less easily marked by a blow. The child becomes a well
grown boy before he paces the length and breadth of rooms so as to
compare their areas and add to his mensuration lesson an example from
home. If instead of pacing he were to use a foot-rule, or a tape-line, so
much the better. About this time he may begin to observe the thermometer,
noting that within five hours, let us say, it has fallen eight degrees. As a
child he took account of bigness or smallness, lightness or heaviness,
warmth or cold; now he passes to measuring their amount. In so doing he
spans in a few years what has required for mankind ages of history. When
corn and peltries are bartered, or axes and calumets are bought and sold, a
shrewd guess at sizes and weights is enough for the parties to the bargain.
But when gold or gems change owners a balance of delicacy must be set up,
and the moral code resounds with imprecations on all who tamper with its
weights or beam. Perhaps the balance was suggested by the children’s
teeter, that primitive means of sport which crosses one prone tree with
another, playmates rising and falling at the ends of the upper, moving trunk.
In essence the most refined balance of to-day is a teeter still. Its successive
improvements register the transition from merely considering what a thing
is, whether stone, wood, oil or what not, to ascertaining just how much
there is of it; or, in formal phrase, to make and use an accurate balance
means passing from the qualitative to the quantitative stage of inquiry.
Before Lavoisier’s day it was thought that any part of a substance which
disappeared in burning was annihilated. Lavoisier carefully gathered all the
products of combustion, and with scales of precision showed that they
weighed just as much as the elements before they were burned. He thus laid
the corner-stone of modern chemistry by demonstrating that matter is

invariable in its total quantity, notwithstanding all chemical unions or
partings. Phases of energy other than gravity are now measured with
instruments as much improved of late years as the balance; they tell us the
great truth that energy like matter is constant in quantity, however much it
may vary from form to form, however many the subtle and elusive
disguises it may wear.
How the foot, our commonest measure, has descended to us Foot and Cubit.
is an interesting story. The oldest known standard of length,
the cubit, was the distance between the point of a man’s
elbow and the tip of his middle finger. In Egypt the ordinary cubit was
18.24 inches, and the royal cubit, 20.67 inches. A royal cubit in hard wood,
perfectly preserved, was discovered among the ruins of Memphis early in
the nineteenth century. It bears the date of the reign of Horus, who is
believed to have become King of Egypt about 1657 B. C. The Greeks
adopted a foot, equal to two-thirds of the ordinary Egyptian cubit, as their
standard of length. This measure, 12.16 inches, was introduced into Italy,
where it was divided into twelfths or inches according to the Roman
duodecimal system, thence to find its way throughout Europe.
Units equally important with the cubit were from of old derived from the
finger and the fingers joined. The breadth of the forefinger at the middle
part of its first joint became the digit; four digits were taken as a palm, or
hand-breadth, used to this day in measuring horses. Another ancient unit,
not yet obsolete, the pace, is forty digits; while the fathom, still employed,
is ninety-six digits, as spaced by the extended arms from the finger tips. The
cubit is twenty-four digits, and the foot is sixteen digits. Thus centuries ago
were laid the foundations of the measurement of space as an art. A definite
part of the human body was adopted as a standard of length, and copied on
rods of wood and slabs of stone. Divisors and multiples, in whole numbers,
were derived from that standard for convenience in measuring lines
comparatively long or short. And yet in practice, even as late as a century
ago, much remained faulty. Standards varied from nation to nation, and
from district to district. Carelessness in copying yard-measures, the wear
and tear suffered by lengths of wood or metal, the neglect to take into
account perturbing effects of varying temperatures on the materials
employed, all constrained men of science to seek a standard of

measurement upon which the civilized world could unite, and which might
be safeguarded against inaccuracy.
Here the Government of France took the lead; in 1791 it
The Metric
appointed as a committee Lagrange, Laplace, Borda, System.
Monge, and Condorcet, five illustrious members of the
French Academy, to choose a natural constant from which a unit of
measurement might be derived, that constant to serve for comparison or
reference at need. They chose the world itself to yield the unit sought, and
set on foot an expedition to ascertain the length of a quadrant, or quarter-
circle of the earth, from the equator to the north pole, taking an arc of the
meridian from Dunkirk to Barcelona, nearly nine and one-half degrees, as
part of the required curve. When the quadrant had been measured, with
absolute precision, as it was believed, its ten-millionth part, the metre, was
adopted as the new standard of length. As the science and art of
measurement have since advanced, it has been found that the measured
quadrant is about 1472.5 metres longer than as reported in 1799 by the
commissioners. Furthermore, the form of the earth is now known to be by
no means the same when one quadrant is compared with another; and even
a specific quadrant may vary from age to age both in contour and length as
the planet shrinks in cooling, becomes abraded by wind and rain, rises or
falls with earthquakes, or bends under mountains of ice and snow in its
polar zones. All this has led to the judicious conclusion that there is no
advantage in adopting a quadrant instead of a conventional unit, such as a
particular rod of metal, preserved as a standard for comparison in the
custody of authorities national or international.
What gives the metric system pre-eminence is the simplicity and uniformity
of its decimal scale, forming part and parcel as it does of the decimal
system of notation, and lending itself to a decimal coinage as in France,
Germany, Italy, and Spain. The metre is organically related to all measures
of length, surface, capacity, solidity, and weight. A cubic centimetre of
water, taken as it melts in a vacuum, at 4° C., the temperature of maximum
density, is the gram from which other weights are derived; this gram of
water becomes a measure of capacity, the millilitre, duly linked with other
similar measures. Surfaces are measured in square metres, solids in cubic
metres. Simple prefixes are: deci-, one-tenth; centi-, one-hundredth; milli-,

one-thousandth; deka-, multiplies a unit by ten; hecto-, by one hundred;
kilo-, by one thousand; and myria-, by ten thousand.
As long ago as 1660 Mouton, a Jesuit teacher of Lyons, proposed a metric
system which should be unalterable because derived from the globe itself.
Watt, the great improver of the steam engine, in a letter of November 14th,
1783, suggested a metric system in all respects such as the French
commissioners eight years later decided to adopt.
The nautical mile of 2029 yards has the honor of being the first standard
based upon the dimensions of the globe. It was supposed to measure one-
sixtieth part of a degree on the equator; the supposition was somewhat in
error.
Lord Kelvin, a master in the art of measurement, an
Uses of Refined
inventor of electrical measuring instruments of the Measurement.
highest precision, as president of the British Association
for the Advancement of Science in 1871, said: “Accurate and minute
measurement seems to the non-scientific imagination, a less lofty and
dignified work than looking for something new. But nearly all the grandest
discoveries of science have been but the rewards of accurate measurement
and patient, long-continued labor in the minute sifting of numerical results.
The popular idea of Newton’s grand discovery is that the theory of
gravitation flashed upon his mind, and so the discovery was made. It was by
a long train of mathematical calculation, founded on results accumulated
through prodigious toil of practical astronomers, that Newton first
demonstrated the forces urging the planets towards the sun, determined the
magnitude of those forces, and discovered that a force following the same
law of variation with distance urges the moon towards the earth. Then first,
we may suppose, came to him the idea of the universality of gravitation; but
when he attempted to compare the magnitude of the force on the moon with
the magnitude of the force of gravitation of a heavy body of equal mass at
the earth’s surface, he did not find the agreement which the law he was
discovering required. Not for years after would he publish his discovery as
made. It is recounted that, being present at a meeting of the Royal Society,
he heard a paper read, describing a geodesic measurement by Picard, which
led to a serious correction of the previously accepted estimate of the earth’s
radius. This was what Newton required; he went home with the result, and

commenced his calculations, but felt so much agitated that he handed over
the arithmetical work to a friend; then (and not when sitting in a garden he
saw an apple fall) did he ascertain that gravitation keeps the moon in her
orbit.
“Faraday’s discovery of specific inductive capacity, which inaugurated the
new philosophy, tending to discard action at a distance, was the result of
minute and accurate measurement of electric forces.
“Joule’s discovery of a thermo-dynamic law, through the regions of electro-
chemistry, electro-magnetism, and elasticity of gases was based on a
delicacy of thermometry which seemed impossible to some of the most
distinguished chemists of the day.
“Andrews’ discovery of the continuity between the gaseous and the liquid
states was worked out by many years of laborious and minute measurement
of phenomena scarcely sensible to the naked eye.”
It is with these examples before them that investigators
Further
take the trouble to weigh a mass in a vacuum, to watch Refinements
the index of a balance through a telescope at a distance Needed.
of twelve feet, or use an interferometer to space out an
inch into a million parts. Their one desire is to arrive at truth as nearly as
they can, to bring grounds of disagreement to the vanishing point, and
ensure exactness in all the computations based on their work. As art
advances from plane to plane it demands new niceties of measurement,
discovers sources of error unsuspected before, and avoids these errors by
ingenious precautions. To-day observers earnestly wish for means of
measurement surpassing those at hand. Take the astronomer for example.
One would suppose that the two points of the earth’s orbit which are
farthest apart, divided as they are by about 185,000,000 miles, would afford
sufficient room between them for a base-line wherewith to measure celestial
spaces. But the fact is otherwise. So remote are the fixed stars that nearly all
of them seem unchanged in place whether we observe them on January 3 or
July 3, although meanwhile we have changed our point of view by the
whole length of the ellipse described by the earth in its motion.
Then, too, the chemist is now concerned with analyses of a delicacy out of
the question a century ago. His reward is in discovering the great influence

wrought by admixtures so slight in amount as almost to defy quantitative
recognition. In the experiments by M. Guillaume, elsewhere recited, his
unit throughout every research was one-thousandth of a millimetre, or 1⁄25,400
inch. Argon, a gas about one-fourth heavier than oxygen, forms nearly one-
hundredth part of the atmosphere, and yet its discovery by Lord Rayleigh
dates only from 1894. His feat depended not only upon refined modes of
measurement, but also upon his challenging the traditional analyses of
common air. The utmost resources of refrigeration, of spectroscopy, and of
measurement were required to detect four elements associated in minute
quantities with argon, and of like chemical inertness. These are helium,
having a density of 1.98 as compared with 16 for oxygen; neon, of 9.96
density; krypton, of 40.78; and xenon, of 64. Argon itself has a density of
19.96. “Air contains,” says Sir William Ramsay, “one or two parts of neon
per 100,000, one or two parts of helium per 1,000,000, about one part of
krypton per 1,000,000, and about one part of xenon per 20,000,000; these
together with argon form no less than 0.937 per cent. of the atmosphere. As
a group these elements occupy a place between the strongly electro-
negative elements of the fluorine group, and the very positive electro-
positive elements of the lithium group. By virtue of their lack of electric
polarity and their inactivity they form, in a certain sense, a connecting link
between the two.”[25]
[25] “Gases of the Atmosphere: History of Their Discovery.” Third edition, with portraits.
London and New York, Macmillan, 1906.

As measurements become more and more precise they Precise
afford an important means of discovery. Sir William Measurement as a
Crookes tells us:—“It is well known that of late years Means of
Discovery.
new elementary bodies, new interesting compounds have
often been discovered in residual products, in slags, flue-
dusts, and waste of various kinds. In like manner, if we carefully scrutinize
the processes either of the laboratory or of nature, we may occasionally
detect some slight anomaly, some unanticipated phenomenon which we
cannot account for, and which, were received theories correct and sufficient,
ought not to occur. Such residual phenomena are hints which may lead the
man of disciplined mind and of finished manipulative skill to the discovery
of new elements, of new laws, possibly even of new forces; upon undrilled
men these possibilities are simply thrown away. The untrained physicist or

chemist fails to catch these suggestive glimpses. If they appear under his
hands, he ignores them as the miners of old did the ores of cobalt and
nickel.”[26]
[26] Nineteenth Century Magazine, London, July 1877.

It was a residual effect which led to the discovery of the planet Neptune.
The orbit of Uranus being exactly defined, it was noticed by Adams and
Leverrier that after making due allowance for perturbations by all known
bodies, there remained a small disturbance which they believed could be
accounted for only by the existence of a planet as yet unobserved. That
planet was forthwith sought, and soon afterward discovered, proving in
mass and path to be capable of just the effect which had required
explanation.

Photograph by Cox, Chicago.
PROFESSOR A. A. MICHELSON,
University of Chicago.

Michelson interferometer.

In the measurement of length or motion a most refined
Measurements
instrument is the interferometer, devised by Professor A. Refined: the
A. Michelson, of the University of Chicago. It enables an Interferometer.
observer to detect a movement through one five-
millionth of an inch. The principle involved is illustrated in a simple
experiment. If by dropping a pebble at each of two centres, say a yard apart,
in a still pond, we send out two systems of waves, each system will ripple
out in a series of concentric circles. If, when the waves meet, the crests
from one set of waves coincide with the depressions from the other set, the
water in that particular spot becomes smooth because one set of waves
destroys the other. In this case we may say that the waves interfere. If, on
the other hand, the crests of waves from two sources should coincide, they
would rise to twice their original height. Light-waves sent out in a similar
mode from two points may in like manner either interfere, and produce
darkness, or unite to produce light of double brilliancy. These alternate dark
and bright bands are called interference fringes. When one of the two
sources of light is moved through a very small space, the interference
fringes at a distance move through a space so much larger as to be easily
observed and measured, enabling an observer to compute the short path

through which a light-source has moved. In the simplest form of
interferometer, light from any chosen source, S, is rendered approximately
parallel in its rays by a double convex lens at L. The light falling upon the
glass plate A is divided into two beams, one of which passes to the mirror
M, while the other is reflected to M¹. The rays reflected from M¹, which
pass through A, and those returned from M reflected at d, are reunited, and
may be observed at E. In order to produce optical symmetry of the two
luminous paths, a plate C exactly like A is introduced between A and M.
When the distance from d to M and to M¹ are the same the observer sees
with white light a central black spot surrounded with colored rings. When
the mirror M¹ is moved parallel to itself either further from or nearer to A,
the fringes of interference move across the field of view at E. A
displacement of one fringe corresponds to a movement of half a wave-
length of light by the mirror M¹. By counting the number of fringes
corresponding to a motion of M¹ we are able to express the displacement in
terms of a wave-length of light. Where by other means this distance is
measurable, the length of the light-wave may be deduced. With intense light
from a mercury tube 790,000 fringes have been counted, amounting to a
difference in path of about one-fourth of a metre.

Light-wave distorted in passing through heated
air.

Many diverse applications of the interferometer have been developed, as,
for example, in thermometry. The warmth of a hand held near a pencil of
light is enough to cause a wavering of the fringes. A lighted match shows
contortions as here illustrated. When the air is heated its density and
refractive power diminish: it follows that if this experiment is tried under
conditions which show a regular and measurable displacement of the
fringes, their movement will indicate the temperature of the air. This
method has been applied to ascertain very high temperatures, such as those
of the blast furnace. Most metals expand one or two parts in 100,000 for a
rise in temperature of one degree centigrade. When a small specimen is
examined the whole change to be measured may be only about 1⁄10,000 inch, a
space requiring a good microscope to perceive, but readily measured by an
interferometer. It means a displacement amounting to several fringes, and
this may be measured to within 1⁄50 of a fringe or less; so that the whole
displacement may be measured to within a fraction of one per cent. Of
course, with long bars the accuracy attainable is much greater.
The interferometer has much refined the indications of
Application to
the balance. In a noteworthy experiment Professor Weighing.
Michelson found the amount of attraction which a sphere
of lead exerted on a small sphere hung on an arm of a delicate balance. The
amount of this attraction when two such spheres touch is proportional to the
diameter of the large sphere, which in this case was about eight inches. The
attraction on the small ball on the end of the balance was thus the same
fraction of its weight as the diameter of the large ball was of the diameter of
the earth,—something like one twenty-millionth. So the force to be
measured was one twenty-millionth of the weight of this small ball. In the
interferometer the approach of the small ball to the large one produced a
displacement of seven whole fringes.
In order that this instrument may yield the best results, great care must be
exercised in its construction. The runways of the frame are straightened
with exactitude by a method due to Mr. F. L. O. Wadsworth. The optical
surfaces of the planes and mirrors in the original designs were from the
master hand of Mr. John A. Brashear of Allegheny, Pennsylvania. Each
mirror is free from any irregularity greater than 1⁄880,000 inch, and the
opposite faces of the mirrors must be parallel within one second of arc, or
1⁄1,296,000 part of a circle.[27]

[27] Interferometers in a variety of designs are manufactured by William Gaertner & Co.,
5347 Lake Avenue, Chicago.

Now for a word as to Professor Michelson’s suggestion A Light-Wave as
that an unvarying unit of measurement may be found in a an Unvarying
certain light-wave, as observed in the interferometer. Unit of Length.
Everybody knows that each chemical element burns with
colors of its own. When we see red fire bursting from a rocket we know that
strontium is ablaze; when the tint is green it tells us that copper is on fire, as
when a trolley-wheel jumps from its electric wire. When these sources of
light are looked at through an accurate prism of glass in a spectroscope they
form characteristic spectra, and these spectra in their peculiarities of color
reveal what elements are aflame. In most cases the rays from an element
form a highly complicated series; to this rule cadmium, a metal resembling
zinc, is an exception. It emits a red, a green, and a blue ray; the wave-
lengths of these rays Professor Michelson proposes as a basis of reference
for the metallic standards of length adopted by the nations of Europe and
America. He says: “We have in the interferometer a means of comparing
the fundamental standard of length with a natural unit—the length of a
light-wave—with about the same order of accuracy as is at present possible
in the comparison of two metre-bars, that is, to one part in twenty millions.
The unit depends on the properties of the vibrating atoms of the radiating
substance, and of the luminiferous ether, and is probably one of the least
changeable qualities in the material universe. If therefore the metre and all
its copies were destroyed, they could be replaced by new ones, which
would not differ among themselves. While such a simultaneous disaster is
practically impossible, it is by no means sure that notwithstanding the
elaborate precautions that have been taken to ensure permanency, there may
not be slow molecular changes going on in all the standards, changes which
it would be impossible to detect except by some such method as that here
presented.”
Thus, by dint of mechanical refinements such as the world never saw
before, some of the smallest units revealed to the eye become the basis of
all measurement whatever, reaching at last those cosmical diameters across
which light itself is the sole messenger. In the early days of spectroscopy
many doubters said, What good is all this? Since then a full reply has been
rendered to their question and, at this unexpected point, the spectroscopic

examination of an unimportant metal may afford a measuring unit of ideal
stability. Cases like this suggest the query, Is any knowledge whatever quite
worthless?

CHAPTER XVII
MEASUREMENT—Continued

Weight, Time, Heat, Light, Electricity measured with new precision . . . Exact measurement means
interchangeable designs, and points the way to utmost economies . . . The Bureau of Standards at
Washington . . . Measurement in expert planning and reform.

Ancient Egyptian balance.

ur grandfathers supposed that trade began in barter;
O The Balance in
we have been able to go one step further back in Measurement.
history to find that barter followed upon the
custom of exchanging presents. This custom, among shrewd and self-
respecting people, came at length to a degree of fairness, and led to rough
and ready modes of weighing, gradually improved. In the British Museum,
in a papyrus of Hunnafer, who lived in Egypt thirty-three centuries ago, we
have pictured a well-constructed balance of equal arms, in which a feather
is outweighing a human soul. In its successive improvements the balance

registers the progress of many arts and sciences, and in its turn has
promoted them all. It must be built of a metal, or an alloy, hard, durable,
and not easily corroded. Its centre of motion should be a little above its
centre of gravity; its knife edge should have an angle of about 60 degrees.
Appliances must render it easy to lift the weighing apparatus when out of
use, so that unnecessary wear of the knife edge may be avoided, as well as
needless strain throughout the structure. Air currents should be kept off by a
suitable case, or, better still, the instrument should be enclosed in a receiver
exhausted of air altogether. The weights, made with scrupulous care of
standard metal or alloy, should be guarded from tampering, abrasion, and
corrosion, from dirt or other accretions. A weighing should be slowly
performed, the weights placed in the center of one pan, the object weighed
in the center of the other pan; to eliminate errors due to inequality in the
length of arms, the article weighed and the weights are then made to
exchange places. The platform should be of the utmost strength and rigidity,
so as precisely to maintain its level at all times.

A Rueprecht balance.

As long ago as 1798 a balance was erected having an accuracy of one part
in 1,600,000; fifty years later ten-fold greater accuracy had been attained;
to-day results much more astonishing are achieved. A precision balance
manufactured by Messrs. Albert Rueprecht & Son, Vienna, is shown on
page 220, as furnished in 1902 to the International Bureau of Weights and
Measures at Sevres, France. It is provided with means for applying the
smallest weights of platinum from a distance of three to four metres, so as
to guard against perturbations due to the warmth of an operator’s body. The
weights may be shifted from one pan to the other, and the oscillations
observed through a telescope, at a distance of four metres. This balance will
detect the 1⁄500 of a milligram when weighing a mass of 500 grams, or one
part in 250,000,000. Such balances, and those of Paul Bunge, of Hamburg,

require ten to twenty months of skilled labor for their completion. The
International Bureau of Weights and Measures has a balance of
extraordinary sensitiveness at the Pavillon de Breteuil, Sevres, where the
work of the Bureau goes forward. This instrument measures the difference
in the attraction of the earth for a mass of one kilogram when that weight is
moved nearer to or farther from the centre of the earth by as little as one
centimetre. Thus placing two weights, of common shape, each a kilogram,
one on top of the other, and two other weights in the other pan beside one
another, would introduce a noteworthy difference in a comparison.
At the very dawn of civilization, the day, however Measurement of
crudely, was divided into parts. These parts, long Time.
afterward, probably in Babylonia, became the twenty-
four hours which have descended to us. The means of time-keeping came
first, in all likelihood, from measuring the simple shadow of a stick, the
gnomon, still set up as a sun-dial in our gardens. Next came an hour-glass
with its falling sand; the clepsydra, with its water dropping from a jar; the
burning of candles definite in length. At last came the supreme discovery
that a pendulum, of given length, if kept in one place oscillates in an
unvarying period, be its arc of motion long or short. Tradition has it that in
Arabia, about the year 1000 A. D., the pendulum was used in time-keeping.
Granting this to be true, we must nevertheless give Galileo credit for his
independent discovery as he observed the swaying lamp of the cathedral at
Pisa, early in the seventeenth century. In 1657 Huygens employed a
pendulum in the construction of a clock which, of course, displayed a new
approach to accuracy. In 1792 Borda and Cassini had improved their time-
pieces so as to be correct within one part in 375,000, that is to one second in
104 hours. For the sake of portability, clocks were gradually reduced in size
until they became watches. Instead of a pendulum they were furnished with
its equivalent, a balance wheel, Pierre Le Roy having discovered that there
is in every spring a certain length where all the vibrations, great or small,
are performed in approximately the same period. For actuation, watches
were provided with mainsprings which have steadily undergone
improvement in quality and in placing.
Many refinements have brought the time-keeper for the Time-Pieces
ship, the observatory, the railroad, to virtual perfection. Improved.
Its wheels, pinions, balance-staffs are manufactured

automatically, as at Waltham, Massachusetts, to an accuracy of 1⁄5000 inch or
even less, thanks to that great inventor, Mr. Duane H. Church. In modern
watch-making the most durable materials are used, magnetic perturbations
are avoided by employing alloys insensitive to magnetism, and the effects
of fluctuating temperatures are withstood by Earnshaw’s compensated
balance wheel. This wheel is in halves, each nearly semicircular and
attached at one end to a stout diameter. Its outer rim, being made of brass,
when warmed expands more than its inner rim of steel. Thus, in a rising
temperature the wheel curves inward with its duly placed weights, so that
the reduction in elasticity of the hair-spring caused by heat is compensated.
Experiments are afoot which look toward a marked improvement in the
making of time-pieces, by using invar, a nickel-steel with practically no
expansibility by heat. This alloy is already employed for pendulums with
satisfactory results, both at the Naval Observatory and at the Bureau of
Standards, in Washington. It has been described on page 169.

Earnshaw compensated balance wheel for
watches.

At the Paris Observatory the standard clock, by Winnerl,
The Best Clocks in
is in a vault twenty-seven metres underground. At that the World.
depth the temperature changes are less than one fifth of a
degree during the year, yet the effect of barometric changes on the rate of
the clock have proved to be serious. This difficulty is avoided in the Naval

Observatory at Washington, by enclosing the standard clock in an air-tight
case within which the air is reduced to a pressure lower than that ever
shown by a barometer at that level. To avoid risks of air leaking through
this case were it to be pierced by a moving axle, this clock is actuated by
weights lifted electrically by a small primary battery. The slight electric
current required has no perturbing effect on the clock. This time-piece,
provided with an escapement of great excellence, was manufactured by
Clemens Riefler of Munich.
At the Observatory of the Case School of Applied Science, Cleveland,
Ohio, another Riefler clock has a mean error of but .015 second per day.
This means that in a year the total error is not more than 5.475 seconds, or
one part in 5,760,000 of the 365 days. Such errors, minute as they are, give
a good deal of trouble when they are irregular, that is, when the clock is
sometimes slow, sometimes fast, in a fashion apparently lawless. When the
divergences are fairly constant they can usually be traced to their source,
making it feasible to apply a remedy.

Riefler clock.

A pendulum which swings once in a second at the base
Ascertaining the
of a tall tower will require for the same travel a little Force of Gravity.
more than a second when borne to the top of the tower,
because then further from the centre of the earth. Still greater will be the
difference in its periods as it swings first at the base of a mountain and next
at its summit. A pendulum, therefore, is a means of learning the force of
gravity at a given place, and without sacrifice of accuracy it is well that it
should be as small as possible. In 1890, Professor T. C. Mendenhall, then
superintendent of the United States Coast and Geodetic Survey, designed a
pendulum one fourth the length of those previously used, and of admirable
precision. Afterward pendulums were built of dimensions further reduced to
about two and one half inches in length, with periods of oscillation of one
fourth of a second. Such pendulums are easily carried to stations difficult of
access, and have been employed on the summits of high mountains,
including Pike’s Peak: their indications agree well with those of the larger
and somewhat cumbersome apparatus previously used.
Much the most convenient means of measuring
Heat Measured.
temperature is the common glass tube filled with mercury.
This metal is chosen because a liquid, and because it varies
extremely in bulk when warmed or cooled. Materials of parallel
susceptibility are adopted for instruments which measure the intensity of
magnetism or of electricity, the working core of the instrument being made
of a substance highly responsive to magnetism or to electricity.
A mercurial thermometer, for all its convenience, has its accuracy assailed
on more sides than one. When the barometric pressure rises, the bulb is
compressed; when the barometer falls, the bulb enlarges by virtue of the
diminution in atmospheric pressure. Further, when its graduated tube is
upright the mercury exerts a distending pressure which introduces error. At
all temperatures the metal is giving off a vapor which has tension, in its
upper ranges entailing marked inaccuracies. The glass itself of which the
instrument is made, when of ordinary composition, spontaneously
undergoes changes of volume. While this is a minor source of error it may
be almost completely avoided by using a boro-silicate glass from the
factory of Schott & Genossen, at Jena. Other substances than mercury are

employed in thermometers with gratifying results. Hydrogen gas is found
very suitable within the interval from -30° to 200° Centigrade. Pentane
serves in temperatures reaching down to -180°.
But it is in alliances with electricity that the measurement of heat has its
broadest scope and utmost exactitude. It was long ago remarked that
heating a metallic conductor increases its resistance to the flow of an
electric current; to measure that resistance in a platinum wire serves,
therefore, to measure its temperature. An instrument on this principle is the
bolometer of the late Professor S. P. Langley, of Washington. Through a
strip of platinum barely 1⁄500 inch in width, and less than 1⁄5000 inch in
thickness, a current of electricity flows continuously. When radiation,
visible or invisible, on occasion from a star, falls upon it, the strip when
warmed by as little as one millionth of a degree duly records the fact. An
instrument, modified from the Crookes radiometer by Professor E. F.
Nichols of Columbia University, New York, is more sensitive still. An
exhausted hollow metal block has a window of fluorite, a mineral
transparent to ether vibrations of a long range of frequencies. Suspended
inside the block is a fine quartz fibre supporting a horizontal bar, at the ends
of which are attached thin plates of mica, blackened on one side. Rays
passing through the fluorite window strike the blackened side of the mica,
which is parallel and opposite to it. The resulting rise in temperature causes
the vane to revolve against the torsion of the quartz fibre. The angle of
torsion when thermal equilibrium is reached, measures the intensity of the
incident radiation.
Another principle is adopted in the electrical instruments which expose to
heat a junction of two different materials, usually metallic, giving rise to an
electric current, easily measured. Experience shows that the most
satisfactory couples for temperatures between 300° C. (570° F.) and 1600°
C. (2900° F.) are those devised by M. Le Chatelier, one half consisting of
pure platinum, the other half an alloy of ten per cent. rhodium and ninety
per cent. platinum. Such instruments are indispensable in the arts which
employ high temperatures. In producing chlorine by the Deacon process, or
in the baking of porcelain, an undue variation of temperature of only twenty
degrees may cause a complete failure of the operation.

It is probable that about one half the electricity from the
The Measurement
dynamos of America is sent into lamps, and this is but of Light.
part of the whole outlay for light, still chiefly produced
by petroleum and gas. Hence the importance of measuring the light from
lamps, jets, and mantles of various kinds, and testing the efficiency of
shades and reflectors. First of all comes the decision as to a standard for
comparison. Great Britain has adopted the Harcourt lamp, consuming
pentane, as a standard for ten candle-power, referring to the old time candle
of spermaceti. Germany employs the amylacetate lamp introduced by Von
Hefner Alteneck, as a standard for its Hefner unit of illumination. Both
lamps share in a difficulty which attends all combustion: atmospheric
conditions which vary from hour to hour, from place to place, greatly affect
the intensity of a flame. Hence incandescent lamps, which have been
compared with these fundamental standards, are used as working standards.
They can be operated by a uniform current of specified voltage, and after a
hundred hours’ use their constancy of radiation for a considerable period is
remarkable.

Photometer. A, standard candle. B, gas flame. S, sliding frame.

Having settled upon a standard candle or lamp the measurement of light
demands extreme care, and, at the best, can never approach the accuracy of
other laboratory measurements. Many photometers have been invented,
some of them highly elaborate, but the type oftenest used remains in
essence the simple instrument long ago devised by Bunsen. On a frame
supported by a stand, S, is stretched a sheet of white paper in the centre of
which is a grease spot. This spot allows more light to pass through it and

consequently reflects less than the unmarked portion of the paper. If the
sheet is more strongly lighted from behind than from in front, it appears
bright on a dark ground. If it is illuminated more strongly in front than at
the back it will seem dark upon a bright ground. When equal lights fall on
both sides, the spot becomes invisible, since it can then appear neither
darker nor brighter than the surrounding paper. In its simplest use the screen
is placed between a standard candle or lamp at A and the light to be
measured at B: the screen is moved along its graduated slide until the grease
spot vanishes. If the screen is twice as far from B as from A when the spot
disappears, then B is four times as intense as A in light; if the screen were
thrice as far from B as from A, then B would be nine-fold as bright as A, the
intensity of light diminishing as the square of the distance of its source.
An open-arc lamp, without a reflector, sends to the ground a fairly wide ring
of brilliant rays; on both sides of that ring the illumination is feeble. Other
sources of light also vary a good deal in the brilliancy of the beams which
they emit in various planes. It is therefore usual to measure the light from a
lamp as sent forth in all planes, or at least in its principal planes. When
incandescent lamps are brought to a photometer they are as a rule placed on
a spindle turning so swiftly that their mean horizontal candle-power may be
read at once. For measuring the mean spherical intensity a photometer
devised by Professor Matthews of Purdue University is employed. This
apparatus has a series of mirrors arranged in a semicircle around a lamp,
reflecting all the received light upon a single surface.
Light may have great brilliancy and yet be undesirable from its color; we
are all familiar with the havoc that gas light may play with hues of blossom
and leaf that in sunshine are beautiful. Through ages untold the human eye
has been seeing by rays from the sun, and from immemorial habit is best
served by light of similar quality. A simple instrument, the spectrometer,
casts upon a screen the spectrum from a mercury tube, a Nernst lamp, a
Welsbach mantle, or other illuminant, and enables us to compare it with the
spectrum of sunshine. Then, as in placing a light pink shade over a
Welsbach mantle, we act on the intimations of analysis greatly to the relief
of the eye.
An incandescent bulb or mantle may be satisfactory both in brilliancy and
color, but a further question is, How long will the filament or the mantle

last, and at what point in deterioration should it be discarded? Tests during
the first, the fiftieth, the hundredth, and other successive hours will tell us
how much the intensity falls off. Just when a bulb or a mantle should be
dismissed from service depends partly on the rate of deterioration, and
partly on the prices of bulbs and current, of mantles and gas.
Hardly less important than testing sources of light is the investigation of
their reflectors and shades. As a rule our lamps are too brilliant, and in
many cases they send their light in wasteful directions. It is a general and
absurd practice to buy a dollar’s worth of light and then kill sixty cents’
worth of it with a thick opal or cut-glass shade. Examination with the
photometer has revealed that many popular patterns of reflectors and shades
are most ineffective, while those of the Holophane make, when kept
scrupulously clean, send the light just where it does most good and at the
lowest possible expenditure of energy. This theme has attention on page 78.
[28]

[28] A capital treatise on the subject of lighting, and the measurement of light, is Louis
Bell’s “Art of Illumination.” New York, McGraw Publishing Co., 1902. $2.50. Its author
(August, 1906) is preparing a new and revised edition.

The sky has been the supreme field for measurements The Sky as a Field
more refined from age to age. Professor William Stanley for Measurement.
Jevons, in “Principles of Science,” says: “At Greenwich
Observatory in the present day, the hundredth part of a second is not
thought an inconsiderable portion of time. The ancient Chaldeans recorded
an eclipse to the nearest hour, and even the early Alexandrian astronomers
thought it superfluous to distinguish between the edge and centre of the sun.
By the introduction of the astrolabe, Ptolemy and the later Alexandrian
astronomers could determine the places of the heavenly bodies within about
ten minutes of arc. But little progress then ensued for thirteen centuries,
until Tycho Brahe made the first great step toward accuracy, not only by
employing better instruments, but even more by ceasing to regard an
instrument as correct. Tycho, in fact, determined the errors of his
instruments, and corrected his observations. He also took notice of the
effects of atmospheric refraction, and succeeded in attaining an accuracy
often sixty times as great as that of Ptolemy.

“Yet Tycho and Hevelius often erred several minutes in the determination of
a star’s place, and it was a great achievement of Roemer and Flamsteed to
reduce this error to seconds. Bradley, the modern Hipparchus, carried on the
improvement, his errors in right ascension being under one second of time,
and those of declination under four seconds of arc according to Bessel. In
the present day the average error of a single observation is probably
reduced to the half or quarter of what it was in Bradley’s time; and further
extreme accuracy is attained by the multiplication of observations, and their
skilful combination according to the method of least squares. Some of the
more important constants, for instance that of nutation, have been
determined within the tenth part of a second of arc.
“It would be a matter of great interest to trace out the dependence of this
vast progress upon the introduction of new instruments. The astrolabe of
Ptolemy, the telescope of Galileo, the pendulum of Galileo and Huygens,
the micrometer of Horrocks, and the telescopic sights and micrometer of
Gascoyne and Picard, Roemer’s transit instrument, Newton’s and Hadley’s
quadrant, Dollond’s achromatic lenses, Harrison’s chronometer, and
Ramsden’s dividing engine—such were some of the principal additions to
astronomical apparatus. The result is that we now take note of quantities
1⁄300,000 or 1⁄400,000 the size of the smallest observable in the time of the

Chaldeans.”

Compass needle deflected by an electric current borne in a wire.

Compass needle deflected by an electric current borne in a coil.

Suspended coil with D, soft iron core. N,
S, magnetic poles.

As important as the measurements of the astronomer are
Electricity
those of the electrician. It was as recently as 1819 that Measured.
Oersted, a Danish physicist, published a discovery which
became a foundation stone of electrical engineering, and upon which rises
the art of electrical measurement. He observed that when an electric current
is passing through a wire, a nearby magnetic needle tends to place itself at
right angles to the wire, the deflection varying with the strength of the
current. When instead of a wire, a coil, duly insulated, is employed to carry

the current, effects much more decided are displayed. At first current-
measurers, or galvanometers, employed simple compass needles; these
proved to be unsatisfactory. They were affected by the variations which
occur in the intensity of the earth’s magnetism; and no matter how carefully
a needle was made, it varied in strength from week to week, from year to
year; again, a current might be so strong as to create magnetism
overwhelming in comparison with that of the earth, and quite beyond the
measuring power of a compass needle. A galvanometer on a plan due to
Professor James Clerk Maxwell, employs a permanent magnet, or an
electro-magnet, which is stationary, between the poles of which may freely
turn a coil bearing the current to be measured. This current in the case of an
ocean cable is so weak that no other means of indication will serve. Lord
Kelvin’s recording apparatus for such a cable is a galvanometer on this
principle. In order to concentrate the lines of magnetic force on the vertical
sides of the coil, a piece of soft iron, D, is fixed between the poles of the
magnet. This iron becomes magnetized by induction, so as to produce a
very powerful field of force, in the minute spaces between it and the two
magnetic poles, through which spaces the vertical sides of the coil are free
to move. Instruments of this kind, developed by D’Arsonval, are known by
his name.
Instruments for electrical measurement, with stationary Weston
magnets and moving coils, of great excellence, are Instruments.
manufactured by the Weston Company, Waverly Park,
New Jersey. Their accuracy rests upon several important discoveries by Dr.
Edward Weston: first, a method of making a magnet which is really
permanent, retaining its original strength for a long time: second, by the
preparation of a remarkable group of alloys which under ordinary variations
of temperature manifest scarcely any change in conductivity, and which set
up but little thermo-electric action as they touch other metals in an
instrument. Let us see how a Weston voltmeter, or measurer of electric
pressure, is constructed.

Weston voltmeter.

A light rectangular coil of copper wire, C, is wound on an aluminium frame
pivoted in jeweled bearings so as to be free to rotate in the ring-like space
between an inner cylindrical soft iron core, K, and the pole pieces P and P
of the permanent magnet, M. A light aluminium pointer, p, is attached to the
coil and is free to move across the scale, D. The current enters the coil
through the two spiral springs S and S, which serve also to control the
movement of the coil. When a current passes through the coil the dynamic
action between the current and the magnetic field tends to rotate the coil,
and the position of equilibrium between this force and the torsion of the
springs, indicated by the pointer, measures the current passing through the
coil. Because the magnetic field is practically unvarying throughout, and
the torsion of the springs is proportionate to their deflection, the scale is
virtually uniform. This is not assumed in their manufacture, however, for
each instrument is calibrated by direct reference to standards. As the
aluminium frame moves through the magnetic field, slight currents are
generated within the metal; these serve to dampen vibrations so that the
pointer comes to rest almost instantly without friction. That the magnetic
field may have the utmost strength, the air gap in which the coil rotates is
made as narrow as possible; this is ensured by workmanship of the highest

skill, and by tools specially designed. The hardened steel pivots are ground
and centered as in the best watch-making: the coil is balanced by means of
adjustable weights so that none but electrical forces may come into play. In
a Weston voltmeter of regular type, the maximum current required for a full
scale-deflection is only 0.01 ampere. Instruments of much higher sensibility
are constructed for measuring insulation, requiring but 0.0006 ampere for
the same deflection. So much for the task of measuring electrical pressure.
For measuring electrical currents, which differ from pressures as the
quantity of water flowing in a pipe differs from the pressure of that water as
shown in a common gauge, a Weston ammeter, or ampere-meter, may be
employed. It is similar to the voltmeter just described, being in fact a milli-
voltmeter actuated by the difference in electrical potential, or pressure,
between the terminals of a standard resistance, the shunt, through which a
definite fraction of the current passes. It is as if a known part of the flow of
a river being measured, the volume of the whole stream is learned.
The two principal alloys discovered by Dr. Weston, and used in his
instruments, are manganin and nickelin. Manganin has about twenty-five
times the resistance of copper, and increases in resistance about 0.00001 for
each degree Centigrade through which its temperature rises. Nickelin has
about twenty-nine times the resistance of copper, and decreases in
resistance about 0.00004 for each degree Centigrade through which its
temperature rises. These and other alloys used in construction are carefully
worked and annealed according to methods perfected in years of
experience. After a wire for an instrument is drawn, its fibres, being in a
state of unequal strain, undergo an artificial aging process so that their
resistance shall remain unchanged after adjustment. The Weston
instruments are based on the international volt and ampere adopted by the
National Bureau of Standards at Washington. Instruments of the regular
portable type have a guaranteed accuracy of one part in 400, while the
laboratory standard semi-portable instruments are guaranteed to one part in
1000. Weston voltmeters and ammeters are constantly being checked after
years of active service, and are found correct within the guaranteed limits of
accuracy.
This remarkable success testifies to the importance of asking, What
properties are needed in the material of which an instrument is to be built?

That question duly answered, it becomes a task for research to provide these
materials, that skill may put them together in compact and convenient form.
[29]

[29] In taking notes for this book the author has visited many factories, works, and mills. In
design, equipment, and operation the Weston factory is the best of them all and quite above
criticism. Admirable, too, are the educational and social features of this establishment.

Whether in the laboratory of the chemist or the physicist, The Bureau of
in the machine shop or the engine-room, every means of Standards at
measurement must be based on standards created with Washington.
the highest skill and guarded with the utmost care. For
the United States these ultimate standards, in full variety, are brought
together at the Bureau of Standards at Washington, of which Dr. S. W.
Stratton is director. Here are safeguarded copies of the international metre
and the kilogram adopted by Executive Order in 1893 as fundamental units
of length and mass; here, too, are standard yards and pounds, bearing fixed
legal relations to the international metre and kilogram. The Bureau is
prepared to determine the length of any standard up to fifty metres, to
calibrate its subdivisions, and to determine its coefficient of expansion for
ordinary temperatures. To the credit of American workmanship be it said
that at times the micrometers received from leading manufacturers, for use
in workshops of the best class, are so refined in their measurements as to
tax to the utmost the resources of the Bureau. Its precision balances, by
Rueprecht of Vienna, and Stuckrath of Berlin, weigh a kilogram within 1⁄200
part of a milligram, that is, within one two-hundred-millionth part of its
load.
In the department of electricity a resistance may be measured all the way
from 1⁄100,000 of an ohm to 100,000 ohms. Here are voltmeters, and
wattmeters of the best types. Magnetism, as swiftly summoned or dismissed
in the cores of dynamos and motors, is here measured with the utmost
exactitude. In some of the instruments fused quartz has been used as a
means of suspension because its high elasticity and great strength allow it to
be drawn as extremely fine threads. Dr. K. E. Guthe, now of the University
of Iowa, while at the head of the section of magnetic measurements, found
that fibres equally serviceable may be drawn from steatite, or soapstone,
such as forms a common kind of gas-burner. Thick quartz threads break
easily when bent, those of steatite do not.

In thermometry, a section in charge of Dr. Waidner, much work goes
forward in testing clinical and other thermometers for manufacturers. The
whole range of heat measurement is covered by instruments adapted to
recording the highest attainable temperatures until we reach apparatus by
which, through observation of its light, the absolute temperature of the
electric arc has been found to be 3720° C. Measurements of light proceed in
another section. Here a photometer designed by Mr. Edward P. Hyde, of the
Bureau staff, has reached the hitherto unexampled accuracy of one part in
200. The Bureau has an extensive workshop where new designs for
improved apparatus are constantly in hand. For services on behalf of the
national or any state government the Bureau makes no charge; moderate
fees are required from firms and individuals. In its new and adequate
quarters the Bureau is doing work as authoritative as that of any similar
institution in the world.

Micrometer caliper measuring 1-1000 inch.
Brown & Sharpe, Providence.

Plug and ring for standard measurements.

In manufacturing modern tools and machinery, the Refined
thousandth of an inch is the usual limit of allowable Measurement
error. A micrometer caliper measuring to this limit is here Improves
Machinery.
shown. The pitch of its screw is 40 to the inch, and the
beveled edge of the screw-thimble is divided into 25
parts, so that motion from one division to the next takes the screw 1⁄25 of 1⁄40
of an inch, or 1⁄1000. By carrying refinement a step farther, 1⁄10,000 of an inch
can be detected. The production of a screw such as this was simply
impossible by the lathe as used almost up to the close of the eighteenth
century, its operator holding in his hand a gouge or chisel. Of inestimable
importance was Henry Maudslay’s invention of the slide-rest which firmly
holds the tool, moving it automatically along the wood or metal being cut.
See illustration on page 96. James Watt, as he endeavored to improve the
steam engine, before the slide-rest was invented, was sorely vexed and
thwarted by the ill-shaped containers for steam which served him as
cylinders. Perhaps the chief task accomplished by the lathe has been its own
improvement, so that to-day surfaces are readily cut by its tools accurately
to within a thousandth part of an inch. Vastly beyond this feat was Professor
H. A. Rowland’s production of a virtually perfect screw, which enabled him
to rule on concave gratings 5.9 inches square, 110,000 lines with such
precision that the error between any two of the lines is probably less than
1⁄3,000,000 of an inch. These gratings brought to view spectra much more

extended and clear than those observable in a spectroscope, however
powerful. The concave plates employed by Professor Rowland were made
by Mr. John A. Brashear of Allegheny, Pennsylvania.
Measurement is greatly indebted to accurate means of enlarging the images
of objects as viewed in the telescope or the microscope. Glass grinding
tools are to-day so exquisitely contoured that a lens forty-two inches in
breadth shows the image of a star as an immeasurable dot. It was in
pressing together two lenses of very large and known radius that Newton
measured the lengths of light-waves. With homogeneous rays, such as those
of yellow light, the successive rings of light and darkness marked the points
at which the intervals between his lenses were equal to half a light-vibration
or any multiple thereof. Measuring these intervals, by noting their distances
from the common centre of his lenses, he found the wave-length of the
particular light he was studying.

Two lenses as pressed together by Newton.

Newton’s rings as produced in yellow light.

The cheap duplication of products, so wonderfully
Interchangeability
expanded of late years, had its germ long before the Old and New.
Christian era, when in Babylonia a builder first made
bricks in a mold, and took care by careful measurement to keep to uniform
dimensions in his output. Because any brick matched any other from the
same mold, he introduced a new beauty and regularity in architecture, he
made it easy to extend or repair a wall, a gateway, a battlement. So it was
afterward with the tiles, also made in molds, which were laid as floors or
roofs; and the piping, likewise molded, for water-supply or drainage. To-
day when a housekeeper replaces her worn-out stove-linings, and a printer
increases his stock of type, they enjoy a direct inheritance from the first
molders of bricks and tiles, cups and bowls. In a modern factory vast sums
are expended in producing the original patterns, molded or copied perhaps

ten million times, so that their cost, in so far as represented in each
manufactured hook or lever, is next to nothing. Much expense, also, is
entailed in making the jigs which guide the tools used in lathes or milling
machines to turn out the cases of voltmeters, or a complicated valve-seat. A
jig may cost a hundred dollars and its use may require rare steadiness of
hand, the utmost keenness of eye; all the while the operator’s wife, at home,
avails herself of an aid based on the very same principle. What else is the
paper pattern according to which she cuts out a collar, an apron, a baby’s
bib?
In machinery the first introduction of an interchangeability of parts was by
General Gribeauval, in the French artillery service, about 1765. He reduced
gun-carriages to classes, and so arranged many of their parts that they could
be applied to any carriage of the class for which they were made. These
parts were stamped, not forged. The next step in this direction was taken in
America and, as in France, its aim was to improve instruments of war. Eli
Whitney, famous as the inventor of the cotton gin, secured a contract from
the United States Government for 10,000 firearms. These he manufactured
almost wholly by stamping. He introduced machinery for shaping and, as
far as then feasible, the finishing of each part. He also employed a system
of gauges, by which uniformity of construction was assured for every gun
produced. Next came J. H. Hall, of Harper’s Ferry, Virginia, who in 1818
made every similar part of a gun of such size and shape as to suit any other
gun, improving some details of importance.

Flat jig, or guide.

The modern designer of tools, implements and machines takes care that the
parts upon which wear chiefly comes are easily removable so as to be
cheaply replaced. A worn out plowshare is renewed for a dollar or two,
keeping the plow as a whole substantially new. Should the pinion of a

watch be destroyed by accident, it is duplicated from Waltham or Elgin for
a few cents.
To-day rods, wires, screws, bolts, tubes, nails, sheets of metal, are made in
standard sizes. Much the same is true of rails for railroads, girders, eye-bars
for bridges, and the like. Thus the product of any factory or mill may be
used to piece out or to repair work turned out by any other similar concern.
Yet more, if a subway or a tunnel is to be built in a hurry, two or more steel-
works may co-operate in furnishing beams, columns, or aught else, with no
departure from ordinary gauges. Steel works in Pennsylvania have
produced every detail for a bridge erected in Africa, a factory in Germany, a
stamp mill in Canada. At the World’s Congress of electricians held in
Chicago in 1893, units were adopted as international standards, a
noteworthy step toward adopting universal standards in all branches of
engineering. Here progress is to some extent held back by firms and
corporations that produce patterns not always worthy of defence. Standard
forms and dimensions, especially in manufactures for a world-market, are
only decided upon after thorough discussion, so that they are judiciously
chosen. Among feasible shapes and sizes for rails, columns, girders, and the
rest, one is usually best, or a few are best. Why not exhaust every
reasonable means of ascertaining which these are for specific tasks that they
may be freely chosen? Then if individuality prefers its own different
designs, let it do so knowing what the indulgence costs.
Measurements may be conducted in the strict spirit of A Test Shows How
scientific research, not immediately directed to industrial Concrete May be
ends. Methods thus perfected are more and more being Cheaply
Strengthened.
adopted for large questions of industry. Let an example
be presented from the field, briefly touched upon in this
book, of concrete as a material for the builder. Says Mr. C. H. Umstead of
Washington, Pennsylvania:—
“Many thousands of tons of the finer grades of stones from the crushers all
over the country are rejected by engineers for use in concrete foundations
and walls, sand being preferred at greatly increased cost. I prepared
seventy-two three-inch cubes with quartz sand and with varying proportions
of crushed stone which was going to the dump as unfit for foundation work,

and submitted them to crushing tests at periods of fourteen and twenty-eight
days. The proportion of Portland cement was constant.”
From Mr. Umstead’s table of results the following figures are chosen; on
comparing those for the first and third cubes they show that a gain in
strength of forty-three per cent, followed upon using six pounds of crusher
refuse instead of five and one half pounds of sand.
Compressive Strain
Portland Crushed 14 28
Sand Cement Water Refuse Days Days
8.5 lbs. 4.5 lbs. 1 lb. none 2850 lbs. per sq. in. 3670
6 „ 4.5 „ 1 lb. 3 lbs. 3120 „ „ „ 5050
3 „ 4.5 „ 1.125 lbs. 6 „ 3620 „ „ „ 5250

So much for the value of a test in the improvement of an important
manufacture.
Mr. Umstead’s full report appeared in 1903, in the third volume of bulletins
published by the American Society for Testing Materials. This Society,
whose secretary is Professor Edgar Marburg of the University of
Pennsylvania, Philadelphia, is affiliated with the International Association
for Testing Materials, one of the most important agencies in existence for
providing the engineer with trustworthy data.
Measurement industrially is taking on a new and rapidly Industrial Uses of
extending scope. It is of great moment that a railroad or a Measurement.
steamship, a factory or a mill, should be built of the best
materials in the most economical way, that it should be equipped with the
most efficient boilers, engines, machines, and lamps: in effect, that every
dollar be expended for the utmost possible value.
At Altoona the Pennsylvania Railroad Company has a laboratory for testing
the materials which go into its roadbed, bridges, tracks, rolling stock,
buildings, telegraph, and signal systems. Every gallon of oil, each
incandescent lamp, car axle, or boiler plate accepted by the Company must
pass a due test in a continuous series of competitive examinations. The huge
scale of such a Company’s purchases, the strains placed upon its equipment
by a service growing in extent and in speed, make this course indispensable.
Take another case, this time in New York, at the power-house of the

Interborough Company in West 59th Street. There every day a fair sample
of the coal brought to the dock is burned, and its heat-units ascertained as a
basis for payment. With a consumption which may rise to 1500 tons a day
this precaution is obligatory.[30]
[30] The United States Geological Survey, Washington, D. C., in 1906 published a report
on the coal testing plant at the Exposition, St. Louis, Mo., 1904. Part I, Field work,
classification of coals, chemical work. Part II, Boiler tests. Part III, Producer-gas, coking,
briquetting, and washing tests. This report, with elaborate tables and many illustrations, is
of great value.
The Pennsylvania R. R. Co., Philadelphia, in 1905 published a large and handsomely
illustrated volume, “Locomotive tests and exhibits, St. Louis, 1904.” $5.00. The
locomotives represented the best American practice of 1904. Every detail of construction
and operation is given in the most instructive manner.
The Company is continuing these tests of locomotives at Altoona, Pa.

On quite other lines, equally important, the ascertainment of values
proceeds at laboratories thoroughly organized for the purpose by staffs at
the service of the public. In the United States the first in rank of such
laboratories are grouped at the Bureau of Standards in Washington. At
leading universities and technological institutes throughout the Union are
other laboratories well equipped for chemical, physical, and engineering
tests. At the Massachusetts Institute of Technology in Boston, for example,
is an Emery testing apparatus for making compression tests of specimens up
to eighteen feet in length, for tension specimens up to thirteen feet. In
Europe analogous institutions are supplemented by the Board of Trade
Laboratories in London, the Laboratoire Central in Paris, the Reichsanstalt
in Berlin. The Electrical Testing Laboratories, a joint-stock concern, has
been established in New York, at Eightieth Street and East End Avenue, for
similar tasks in so far as they come within the electrical field. Its direction
in ability and character is authoritative. Here is some of the best apparatus
in the world for tests of the permeability of magnet iron, of the light from
incandescent, arc, or other electric lamps, of gas-burners and mantles, of the
extent to which reflectors and globes fulfil their purpose, and so on.
It is altogether probable that this concern will be copied in every other large
city of the Union. When an electrical plant is installed it is not enough that
the specifications be drawn with care, it is necessary that verifications of
quality follow upon delivery of dynamos, motors, lamps, and all else. Tests
should be continuous: let us suppose that for a specific task of illumination

Nernst lamps are selected. All very well, but the question is, What quality
has each lamp? Buyers in cases of this kind are more and more referring
rival manufactures to tests which settle, as in a court of final appeal,
differences upon which they themselves are incompetent to pass. Not only
in sale but in production these tests are of the first importance. If a copper
refinery turns out from the same batch of crude metal two samples which
vary by a thousandth in electrical conductivity, it is worth while knowing
every detail which may explain how the better sample was produced. So
likewise in the drawing of wire, the alloying of lead with other metals for
anti-friction bearings, and so on.
It is altogether likely that recourse to authoritative tests will soon become
general. Before many years elapse we may see private and public
laboratories multiplied for the comparison of building and road-making
materials, fuel, boilers, engines, machines, lubricants, finished goods of all
kinds. In the textile industry, for instance, much is said about the waste
entailed in mixing sound wool with shoddy, long staple cotton with short
inferior brands. Let pure and adulterated fabrics be compared in resistance
to wear, and let the effects of scouring, bleaching, dyeing, and mechanical
washing be measured. In another field Professor W. O. Atwater has done
much to ascertain the nourishing value of foods: his labors might well be
extended full circle, not omitting tests of popular medicaments and common
drugs.
To-day engineers of mark are engaged not only to plan a Expert Planning
power-house, a flour mill, a steel works or other vast and Reform.
installation, but also to examine industrial plants
established long ago and enlarged from time to time in an unsystematic
way. Armed with scales, pressure-gauges, indicators, voltmeters, they
ascertain the cost of a horse-power-hour, of making a pound of flour, copper
wire, or aught else. They note how speeds may be heightened with profit, as
by using suitable brands of high-speed steels. They suggest how a pattern
may be adopted in the foundry which will lessen machining; how by-
products now thrown away may be turned to account. They point out how
quality may be improved by the adoption of new machines which may,
furthermore, demand unskilled instead of skilled attendance. They may
advise, from a wide outlook on the whole field of American experience, a
method for equalizing output throughout the day and throughout the year, as

when a central-lighting station sells current at a large discount during the
hours when no lamps are aglow, so that ice may be manufactured at such
periods, or batteries restored for use in automobiles and motor-boats. Mr.
Wilson S. Howell, of New York, a few years ago became convinced that a
neglected branch of economy in central lighting stations was the
maintaining a uniform voltage. He succeeded in reducing fluctuations in
many plants to the unexampled figure of four per cent. The result was that
he lowered the current necessary for an Edison lamp from 3.6 watts to 3.1
watts per candle-power, a saving of one seventh. Mr. M. K. Eyre, another
well-known engineer, once took charge of a lamp factory in Ohio. In four
months he had reduced cost forty per cent. while producing a lamp of the
best quality. An electric lighting and power property which for years had
been unprofitable was placed in the hands of Messrs. J. G. White &
Company of New York, an engineering firm of the first rank. Within a few
months the property was earning a substantial surplus; the ratio of operating
to gross earnings was reduced about thirty per cent., and the gross earnings
showed an increase over corresponding months of the previous year of
nearly forty per cent. Economies quite as striking have been effected by the
firm of Messrs. Dodge & Day of Philadelphia. On request investigators of
this stamp, whose aim is to abolish waste and promote efficiency, go
beyond mechanical and engineering details. They may point out how
needed working capital may be obtained, how best to extend sales, and
possibly how an economical consolidation with other similar plants may be
effected. Almost invariably it is found imperative to recast the bookkeeping
methods, especially with regard to ascertaining the cost of production in
each department. Drawing upon experience recommendations may follow
as to premium plans of paying wages, and other methods of identifying the
interests of employers and employed.[31] Approved schemes for the comfort
and welfare of work people are also suggested by counsellors thoroughly
aware that contentment is great gain, that pure air, good light, and the
utmost feasible safety, contribute to the balance sheet not less than the
quickest lathe tools or the best wound dynamo.

[31] Mr. T. S. Halsey is a contributor to “Trade Unionism and Labor Problems,” published
by Ginn & Co., Boston, 1905. He recites (p. 284) how a corporation had manufactured a
product again and again. Both workmen and foreman were positive that the working time
was at the minimum. The premium plan of payment was introduced, with a reduction in
time of 41 per cent. as the result.

CHAPTER XVIII
NATURE AS TEACHER

Forces take paths of least resistance . . . Accessibility decides where cities shall arise . . . Plants
display engineering principles in structure. Lessons from the human heart, eye, bones, muscles, and
nerves . . . What nature has done, art may imitate,—in the separation of oxygen from air, in flight, in
producing light, in converting heat into work . . . Lessons from lower animals . . . A hammer-using
wasp.

eyond their unending study of forms and properties, their constant
B weighing and measuring, the inventor and his twin-brother, the
discoverer, have a gainful province which now for a little space will
engage our attention. This province is nothing else than Nature, which
begins by offering primitive man stones for hammers, arrowheads, knives;
sticks to serve as clubs, paddles, harrows or tent-poles. We may well believe
that the lowest savages have always exercised some degree of choice even
here; it would be the soundest and sharpest stone that they picked up when
a rude axe was needed. Should only blunt stones be found, then in giving
one of them an edge was taken a first step in art, rewarded with a tool as
good as the axe found ready to hand in some earlier quest. Nature is not
only a giver of much besides stones and sticks, she is virtually a great
contriver whose feats may incite the inventor to reach her goals if he can;
his path will probably differ widely enough from hers as he arrives at
success.
When one drop of rain meets another, and they join
Forces Take the
themselves to thousands more on the crest of a hill, they Easiest Paths.
need no guide posts to show them the easiest course to
the valley. They simply take it under the quiet pull of gravity. When a bolt
of lightning darts across the sky, its lines, chaotic as they seem, are just the
paths where the electric pulses find least obstruction. If a volcano, which
has boiled and throbbed for ages, at last opens a chasm on a hapless shore,
as that of Martinique, we may be sure that at that point and nowhere else
the mighty caldron’s lid was lightest. A cavern in Kentucky, or Virginia,
slowly broadening and deepening through uncounted rills which dissolve its
limy walls, comes at last to utter collapse: the breach marking exactly

where an ounce too much pressed the roof at its frailest seam. In these cases
as in all others, however complex, matter moves inevitably in the path of
least resistance. To imitate that economy of effort is from first to last the
inventor’s task.
Rains, winds and frosts, in their sculpture of the earth Cities and Roads.
have each taken the easiest course; in so doing they have
incidentally marked out the best paths for human feet,
have pointed to the best sites for the homes of men. The stresses of defence
may rear a pueblo on the peak of a perpendicular cliff in New Mexico, but
Paris and London, like Rome, must have all roads leading to their gates; and
the easier and shorter these roads, the bigger and stronger the city will
become. Where New York, Montreal, Chicago, and Pittsburg now stand, the
Indians long ago had the wit to found goodly settlements. They knew, as
well as their white successors, the advantages of paths readily traversed,
and no longer than need be. In this regard there was an instructive contrast
at the outset of railroad building in England. A leading engineer, who
planned some of the earliest English railways, had strong mathematical
prepossessions: he endeavored to join the terminals of his routes by lines as
nearly straight as he could. George Stephenson, for his part, had no
mathematical warp of any kind, but instead much sound sense; his lines
followed the courses of rivers and valleys, and kept, as much as might be, to
the chief indentations of the sea. His roads deviated a good deal from
straightness, but they did so profitably; whereas the lines of his academic
rival, disrespecting the hints and indications of nature, were much less
gratifying from an investor’s point of view. If a traveler takes the New York
Central and Hudson River Railroad from New York to Buffalo he goes
north for 143 miles, to Albany, before he begins to travel westward at all.
Yet this line, keeping as it does to the well-peopled levels of the Hudson
and Mohawk Valleys and serving their succession of cities, towns, and
villages, enjoys the best business, and makes better time between its
terminals than any rival route, because it passes around instead of over its
hills and mountains. By way of contrast we turn to the railroad map of
Russia and observe how Moscow and St. Petersburg are joined by a line
which follows the road which it is said that Peter the Great, with military
exigencies in view, laid down with a pencil and ruler.

Deciduous cypress, Taxodium distichum.

If the engineer has many a golden hint spread before him
Engineering
in the hills and dales, the streams and oceans of the Principles in
world, not less fruitful is the study of what takes place Vegetation.
just beneath the surface of the earth where the roots of
grain and shrub, reed and tree, take life and form. Plant a kernel of wheat in
the ground and note how its rootlets pierce the soil, extending always from
the tip. They need no gardener or botanist to bid them lengthen and thicken
where food chiefly abounds. In an arid plain of Arizona a vine, in ground
parched and dry, goes downward so far, and spreads its fibrils so much
abroad, as soon to show ten times as much growth below the drifting sands
as above them. In fertile, well-watered soil the same vine descends less than
half as far, and yet with more gain. A bald cypress in a swamp of Florida
responds to different surroundings with equal profit. Finding its food near
the surface its roots take horizontal lines, at no great depth in the soil. Every
wind that stirs these roots but promotes their thrift and strengthens their
anchorage. A wealth of sustenance floats in the swamp water. In seizing it
and being thereby fed, the roots develop “knees”; these brace the tree so
firmly against tempests as to win admiration from the engineer. When the
progeny of this cypress grow on well-drained land, the knees do not appear,
while the roots within a narrowed area strike deep. Thus simply in doing

what its surroundings incite it to do, the tree acts as if it had intelligence, as
if it consciously saw and chose what would do it most good.

Deciduous cypress, hypothetical diagram.

Lumbermen in the North observe much the same responsiveness. In a grove
of pines they see that the trees which stand close together are tall and
cylindrical. When all the pines but one in a cluster are cut down, that one
will speedily thicken the lower part of its trunk by virtue of the increased
action of the winds, just as a muscle thickens by exercise.
So also is there responsiveness when we look upon the
The Gain of
life of plants in the large. As the traits of a shrub or tree Responsiveness.
are borne into its seed many a thousand impulses are
merged and mingled. Little wonder that their delicate accord and poise
should be slightly different from those of the seeds from which the parents
sprang. Let us suppose these parents to be cactuses, and that the offspring
displays an unusually broad stem, of less surface comparatively than any
other plant in its group. In a soil seldom refreshed by rain, this cactus has
the best foothold and maintains it with most vigor. Sandstorms which kill
brethren less sturdy, strike it in vain, so that its kind is multiplied. Wherever
such a new character as this gives a plant an advantage, it holds the field
while its neighbors perish. Thus arises a high premium on every useful
variation, be it in new stockiness of form, an acridity which repels vermin,
or a strength which readily makes a way through sun-baked earth. Hence
such new traits are, as it were, seized upon and become points of departure

for new varieties, and in the fullness of time, for new species. About a
hundred years ago a gardener imagined a tuberous begonia, and then
proceeded step by step toward its creation by breeding from every flower
that varied in the direction he desired. This man, and all his kindred who
have added to our riches in cultivated blooms, have no more than copied the
modes of nature which, at the end of ages, bestows as free gifts every
wildflower of the field and hedgerow. If the botanist of to-day is the master
of a plastic art, so is the cattle-breeder who chalks on a barn-door the
outline of a beeve he wishes to produce, and then straightway plans the
matings which issue in the animal he has pictured. Artificial selection, such
as this, is after all only imitation of that natural selection which has derived
the horse from a progenitor little larger than a fox, in response, age after
age, to changing food, climate, enemies, and the needs of his human master.
Fields remote from those of the naturalist are just as Scope for
instructive. The inventor sets before himself an end with Imitation.
conscious purpose, and then seeks means to reach that
end, but at best his methods may be wasteful and imperfect. Nature, with
unhasting tread, acting simply through the qualities inherent in her
materials, through their singular powers of combination, of mutual
adaptability, shows the discoverer results which to understand even in small
measure tax his keenest wit, or displays to him structures at times beyond
his skill to dissect, much less to imitate. Mechanic art, indeed, is for the
most part but a copy of nature, as when the builder repeats the mode in
which rocks are found in caves, in ridges at the verge of a cliff, or in the
stratifications which underlie a county, all conducing to permanence of
form, to resistance against abrading sand or dissolving waters. What ensures
the stability of a lighthouse but its repetition of a tree-trunk in its contour?
Engines and machines recall the animal body, grinding ore much as teeth
grind nuts, lifting water as the heart pumps blood through artery and vein,
and repeating in mechanism of brass and steel the dexterity of fingers, the
blows of fists. When an inventor builds an engine to drive a huge ship
across the sea, he has created a motor vastly larger than his own frame, but
much inferior in economy. At a temperature little higher than that of a
summer breeze the human mechanism transmutes the energy of fuel into
mechanical toil: for the same duty, less efficiently discharged, the steam
engine demands a blaze almost fierce enough to melt grate bars of iron.

Heat is costly, so that its conservation is an art worth knowing. In the ashes
strewn and piled on burning lava nature long ago told us how heat may be
secured against dissipation. Other of her garments, as hair and fur, obstruct
the escape of heat in a remarkable degree, and so does bark, especially
when loosely coherent as in the cork tree. Feathers are also excellent
retainers of heat, and have thereby so much profited their wearers, that
Ernest Ingersoll holds that the development of feathers has had much to do
with advancing birds far above their lowly cousins, the reptiles clad in a
scaly vesture.
As we look back upon the past from the vantage ground
Strength of the
of modern insight we see that men of the loftiest powers Cylinder.
could be blind to intimations now plain and clear. Many
a time have designers and inventors paralleled, without knowing it, some
structure of nature often seen but never really observed. All the variety and
beauty of the Greek orders of architecture failed to include the arch; yet the
contour of every architect’s own skull was the while displaying an arched
form which could lend to temple and palace new strength as well as grace.
The skeleton of the foot reveals in the instep an arch of tarsal and metatarsal
bones, with all the springiness which their possessor may confer upon a
composite arch of wood or steel. Modern builders, whether wittingly or not,
have taken a leaf from the book of nature in rearing their tallest structures
with hollow cylinders of steel. What is this but borrowing the form of the
reed, the bamboo, a thousand varieties of stalk, one of the strongest shapes
in which supporting material can be disposed? Pass a knife across a blade of
pipe or moor grass and you will find a hollow cylinder stayed by buttresses
numbering nearly a score. More elaborate and even more gainful is the way
in which tissue grows in the columns of dead-nettles and bulrushes. The
bones in one’s arms and legs resemble the hollow cylinders of which these
stalks show instructive variations, so that without going beyond his own
frame the designer could long ago have learned a golden lesson. How bone
is joined to bone is scarcely less remarkable, as in the braces of the thigh
bone as it joins the trunk. As bones move upon each other all shock is
prevented by a highly elastic cushion: the springs of vehicles, the buffers of
railroad trains, but repeat the cartilages in the joints of their inventors.

Section of pipe or Cross-section of bulrush,
moor grass. Scirpus lacustris.

In the theodolite and sextant, in the geometric lathe of the bank-note
engraver, are ball-and-socket joints allowing motion in any plane. Equally
free in their movements are the shoulder and hip joints, while their surfaces
are lubricated by a delicate synovial fluid supplied just as it is wanted.
When pumps first received valves to direct their flow in one direction, their
inventor was no doubt gratified at his skill. In the heart within his own
breast, in his veins and arteries, were simple valves engaged in a similar
task as they directed the currents of his blood. In pumps such as are
common in farm-yards, the action is jerky, the stream flowing and ebbing
from moment to moment as the arm rises and falls. The tide of human blood
would have the same uneven pulse were it not for the elasticity of its
arterial walls. Their elasticity serves to equalize the flow, much as the air
does in large chambers on pumps for mines or waterworks.

Human hip joint in section. From “The Human Body,” by
H. N. Martin. Copyright, Henry Holt & Co., New York,
1884. Reproduced by their permission.

Valves of veins.
C, a capillary; H, the heart end of the vessel.
From “The Human Body,” by H. N. Martin.

Copyright, 1884, Henry Holt & Co., New York,
and reproduced by their permission.

Built-up gun.

Examination of the heart brings out a principle in its The Heart and the
structure closely paralleled in modern invention. Guns of Built-up Gun.
old were cast or forged as ordinary columns or shafts are
to-day, the strength of the metal being virtually uniform throughout when
the guns were at rest on their trunnions. As explosive charges more and
more powerful were employed, these guns gave way, the pressure of the
exploding gases stretching the metal at the bore to rupture, before the outer
metal could add its resistance. A modern built-up gun is made up of a series
of, let us say, four cylinders: the first, of comparatively small bore and
thickness, is innermost. It is cooled to as low a temperature as possible,
when a second cylinder is slipped over it red-hot to form a tight fit. Both
masses of metal are now slowly cooled, when a third red-hot, closely fitting
cylinder is passed over them. All three united masses are now cooled, when
the fourth and widest cylinder of all, red-hot, is passed over these three
inner tubes, and the whole gun is allowed gradually to fall in temperature.
When this process is completed the inner parts of the gun, by virtue of the
shrinkage in the metal as it cooled, are under severe compression, while the
outer parts are in as extreme a state of stretch or tension. When such a gun
is fired its inner cylinders oppose much greater resistance to the outward
pressure of the exploding gases than did the walls of the old-time guns. The
strength of the old guns was uniform throughout when they were doing
nothing, and very far from uniform at the instant of firing; a built-up gun,
on the contrary, has uniform strength in its every part just when that
uniformity is wanted, at the moment of explosion. The built-up gun
therefore uses projectiles vastly heavier and swifter than those of former
times. Its structure, made up of cylinders successively shrunk one upon
another, resembles that of the heart, whose two inner parts have their fibres
wound somewhat like balls of twine, these in turn being tightly compressed
by a covering of other fibres. The heart has to resist no such explosive force

as arises within a gun, but in its propulsion of blood through the arteries and
veins it has to exert great pressure, with no rest throughout a lifetime. This
pressure is uniformly distributed throughout the muscular tissue by a
structure which, as engineers would say, has its outer layers in tension and
its inner layers in compression. During twenty-four hours the labor of an
average human heart is equal to lifting two hundred and twenty tons one
foot from the ground.
What building-up does to strengthen the gun has been repeated in the case
of the circular saw: driven at a high speed it becomes so highly heated at its
periphery that the resulting expansion may crack the metal in pieces. In an
improved method of manufacture the saw is hammered to a compression
which gradually increases from rim to centre. In this way the tendency of
the periphery to fly apart is withstood by the compressive forces at the
central portion of the disc.
This ingenious treatment of metal for guns and saws reminds us of a
familiar resource in carpentry, illustrated on page 36. An ordinary book-
shelf, if fairly long and not particularly stout, bends beneath its burden and
may at last slip out from its mortices and fall with injury to its books. At the
outset this is prevented by bending the shelf to convexity on its upper
surface. Then a heavy load no more than brings the shelf to straightness, so
that the books remain in their places with both safety and sightliness. Here a
principle is involved worth a moment’s pause. An inventor asks, What
effect will a working load exert which it is desirable to lessen or withstand?
He gives his structure a form opposite to that which will result from an
imposed burden, so that when at work his structure, a shelf, a cylinder, a
saw, will assume its most effective shape.
From childhood we are familiar with the triangular
The Eye and the
prisms of glass which break a sunbeam into all the hues Dollond Lenses.
of the rainbow. A lens is a prism of circular form, and
has, equally with an ordinary prism, the power to show rays of all colors.
This was for a long time a source of error and annoyance in telescopic
images. Sir Isaac Newton from some rough and ready experiments
concluded that the trouble was beyond remedy, yet all the while his own
eyeballs were transmitting images with little or no vexatious fringe of color.
Let us note how Dollond set about a task which Newton deemed

impossible. He knew, what Newton did not know, that crown glass
disperses or scatters light only half as much as does flint glass, so he united
a lens of the one to a lens of the other, and obtained a refracted or bent
beam of light almost unchanged in its whiteness. Of course, in this
combination there was an increased thickness of glass, but its doubled
absorption and waste of light was a small drawback compared with the
advantage of almost wholly excluding the tinted fringe which had so long
vexed astronomers. In the eyeball are first a crystalline lens, next an
aqueous humor, third a vitreous humor; these three so vary in their qualities
of refraction and dispersion as to render images quite free from color
fringes. Compound lenses on the Dollond principle, repeating the structure
of an eyeball, are used in all good telescopes, microscopes, and cameras,
and are now executed in varieties of Jena glass which bring perturbing hues
to the vanishing point. In their achromatic, or color-free, lenses and their
cameras, or dark chambers, our photographic instruments much resemble
the eye. Indeed, it may be that when we see an object the impression is due
to a succession of fleeting photographs, following each other so rapidly on
the retina as to seem a permanent picture. The eye, furthermore, is
stereoscopic; by uniting two images seen from slightly differing points of
view, it enables us to judge of size, solidity, and distance.

A is flint glass, B, C, F, prism crown glass. C, D, F, prism flint
B is crown glass, more dispersive than crown glass. The
glass. They beam S emerges as E, but little decomposed.
unite to form Were A, B, F a prism of one kind of glass, E
an achromatic would be much decomposed.
lens.
Long before there was a
Limbs and Lungs
philosopher to classify levers into distinct kinds, the foot as Prototypes.
of man was affording examples of levers of the first and

second orders, and his fore-arm of a lever of the third order. Ages before the
crudest bagpipe was put together, the lungs by which they were to be
blown, and the larynx joined to those lungs, were displaying a wind
instrument of perfect model. The wrists, ankles, and vertebrae of Hooke
might well have served him in designing his universal joint. Indeed
weapons, tools, instruments, machines, and engines are, after all, but
extensions and modified copies of the bodily organs of the inventor himself.

Lever of the 1st order.

Lever of the 2nd order.

Lever of the 3rd order.
P, power. F, fulcrum. W, weight.

Canals have called forth the ingenuity of an army of engineers; ever since
the first heart-throb, the circulation of the human blood was exemplifying a
system in which the canal liquid and the canal boats move together, making
a complete circuit twice in a minute, distributing supplies wherever
required, and taking up without stopping return loads wherever they are
found ready. The heart, with its arteries and veins, forms a distributing
apparatus which carries heat from places at which it is generated, or in
excess, to places where it is deficient, tending to establish a uniform,
healthful temperature. To copy all this, with the ventilating appliances
prefigured in the lungs, is a task which in our huge modern buildings
demands the utmost skill of the architect and engineer.

Arm holding ball.

In a great city each branch post office is connected solely
Postal and
with headquarters, to which it sends its letters, papers, Telephonic
and parcels, receiving in return its batches for local Service.
distribution. For each branch office to communicate with
every other would be so costly and cumbrous a plan as to be quite
impracticable. Our postal method is adopted in every telephonic service; Z
communicating with D or M only after he has had his line joined to the
central switchboard which connects with every telephone in the whole
system. All this was prophesied in the remote ancestry of both postmasters
and electricians as their nerves took the paths of what is in effect a complete

telegraphic circuit, with separate up and down lines and a central exchange
in the brain,—that prototype of all other means of co-ordination.
Pianos, organs, and other musical instruments yield their Fibrils of the Ear
notes by the vibration of strings, pipes, or reeds of and Eye.
definite size and form. Across the larynx, the box-like
organ of the throat, the vocal cords vibrate in an identical way. When we
sing a note into an open piano, the string capable of giving out that note at
once responds. Helmholtz believed that in the ear the delicate, graduated
structures, known as the rods of Corti, vibrate in the same way when sound-
waves reach them, giving rise to auditory impressions. Analogous in
operation are the fibrils of the eye which respond to light-waves of various
length and intensities. The human eye has muscles which modify its
globularity, rendering its lenses more or less convex. A cat has a higher
degree of this kind of ability, so that it can dilate its pupil so much as to see
clearly in a feeble light. A man who remains in a darkened room so rests his
nerves of vision that in four or five hours he can readily discern what would
be unseen were he newly brought into the darkness.
Not only in the frame of man, but in the bodies of the The Electric Eel.
lower animals, are suggestions which ingenuity might well
have acted upon in the past, or worthily pursue in the
future. The science of electricity was born only with the nineteenth century
because the gymnotus, or electric eel, had not been understandingly
dissected. Its tissues disclose the very arrangement adopted by Volta in his
first crude battery, namely, layers of susceptible material surrounded by
slightly acid moisture. The characteristics of this eel have their homologies
in the human body; in the muscles which bend the fore-arm, for example,
are nearly a million delicate fibrils comparable in structure with the
columnar organs of the gymnotus. These fibrils are so easily excited by
electricity as to denote an essential similarity of build. Both the columnar
layers of the eel and the fibrils of human muscle are affected in the same
way by strychnine and by an allied substance, curare.
The frames of other animals furnish forth a goodly round
A Beaver Tooth
of analogies with recent products of mechanical and the Self-
ingenuity. A beaver tooth might well have been the Sharpening Plow.
model for a self-sharpening plowshare, widely used

throughout the world. This tooth has a thin outer layer of hard enamel,
within which, dentine, less hard, makes up the rest of the structure.
Gnawing wears the dentine much more than the enamel, so that the tooth
takes on a bevel resembling that of the chisel which pays frequent visits to a
carpenter’s oil-stone. The scale of enamel gives keenness, the dentine
ensures strength, so that the tooth sharpens itself by use, instead of growing
dull. Much the same structure is repeated in a plowshare by chilling the
underskin of the steel to extreme hardness, while the upper face of the share
is left comparatively soft. As it goes through the ground the upper face
wears away so as to yield a constantly sharpened edge of the thin chilled
under metal. Thus the heavy draft of a dull share is avoided without
constant recourse to the blacksmith for re-sharpening.

Beaver teeth.

In another field of ingenuity a great inventor scored a
Shaping a Tube.
success, simply by deliberately taking a lesson from nature.
James Watt, to whom the modern steam engine is most
indebted for its excellence, was once consulted by the proprietors of the
Glasgow Water Works, as to a difficulty that had occurred in laying pipes
across the river Clyde to the Company’s engines: the bed of the river was
covered with mud and shifting sand, was full of inequalities, and subject to
a current at times of considerable force. With the structure of a lobster’s tail
in his mind, Watt drew a plan for an articulated suction-pipe, so jointed as
to accommodate itself to the shifting curves of the river-bed. This
crustacean tube, two feet in diameter, and one thousand feet in length,
succeeded perfectly in its operation. To-day powerful hydraulic dredges

discharge through piping with flexible joints such as Watt devised; in one
instance this piping is 5700 feet in length.

Narwhal with a twisted tusk. Reproduced from
the Scientific American, New York, by
permission.

In many another case art has used a gift of nature simply as received, and
then improved upon it. In making their harpoons the Eskimo used the spiral
teeth of the narwhal; finding their shape advantageous, they copied it for
arrowheads. This is undoubtedly one of the origins of the screw form, of
inestimable value to the mechanic and engineer.
Savages turn birds and beasts to account as food, Lessons from
clothing, and materials for weapons and tools; they also Lower Animals: A
observe with profit the instincts of these creatures. Le Tool-Using Wasp.
Vaillant, the famous explorer, tells us that in Africa the
negroes eat any strange food they see the monkeys devour, well assured that
it will prove wholesome. When the surveyors of the first transcontinental

railroad of America began their labors, they gave diligent heed to the trails
of buffaloes in the Rocky Mountains, believing that these sagacious brutes
in centuries of quest had discovered the easiest passes. In constructive
powers bees, ants and wasps far outrank quadrupeds. Indeed one of the
supreme feats of human architecture, the dome, forms part of the nest of the
warrior white ant, Termes bellicosus.

Lower part of warrior ants’ nest, showing dome.

It is deemed a mark of unusual intelligence when an ape, of kin to man
himself, uses a stone as a hammer wherewith to break open a nut, and yet
the like intelligence is displayed by Ammophila urnaria, as described by Dr.
and Mrs. George W. Peckham in their charming book, “Wasps Solitary and
Social”:[32]
[32] Published by Houghton Mifflin & Co., Boston.

Wasp using a pebble as a hammer. From “Wasps Solitary and
Social,” Copyright, 1905, by George W. Peckham and Elizabeth
G. Peckham. Reproduced by their permission.

“Just here must be told the story of one little wasp whose individuality
stands out in our minds more distinctly than that of any of the others. We
remember her as the most fastidious and perfect little worker of the whole
season, so nice was she in her adaptation of means to ends, so busy and
contented in her labor of love, and so pretty in her pride over the completed
work. In filling up her nest she put her head down into it and bit away the
loose earth from the sides, letting it fall to the bottom of her burrow, and
then, after a quantity had accumulated, jammed it down with her head.
Earth was then brought from the outside and pressed in, and then more was
bitten from the sides. When at last the filling was level with the ground, she
brought a quantity of fine grains of dirt to the spot, and picking up a small
pebble in her mandibles, used it as a hammer in pounding them down with
rapid strokes, thus making this spot as hard and firm as the surrounding
surface.”
It was a wasp, too, which suggested to Reaumur, as he examined its nest,
that wood might well serve as the raw material for paper, and serve it does
to the amount of millions of tons a year. To-day we have as a new fabric for
garments, glanz-stoff, an artificial silk produced from cellulose; its German
manufacturers have imitated as nearly as they could the silk-worm’s thread,