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?

Separation Turns on Diversity of Properties.

Let us note how diverse substances are separated from one another by
taking hold of differences in their properties. When a handful of grain
which has just 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.

Properties Newly Discovered and Produced.

Separations, such as we just considered, turn upon obvious differences
in density. Properties not obvious, yet highly useful, come into view
year by year as 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.

Edison’s Warehouse as an Aid.

Mr. Edison, for aid in finding just the substance he needs for a new
purpose, has at his laboratory in Orange, New Jersey, a large store-room
filled with materials of all 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.

Light Giving Properties.

Mr. Edison has achieved triumphs not only in giving sound its lasting
registration, but in producing an electric 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.

How the Gas Mantle was Invented.

Early in the day of gas-making it was noticed that gases of various
kinds differed much in light-giving quality. It was presently shown that
their light depended on the 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.

[Illustration: DR. CARL FREIHERR AUER VON WELSBACH OF VIENNA.]

[Illustration: 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.

Improvements in Electric Lighting: Incandescent Lamps.

While the Welsbach mantles have been constantly improved in quality, and
given new and inverted forms of special value, the inventors in the
field of electric 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.

[Illustration: 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.

[Illustration: 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.

[Illustration: Tantalum lamp.]

[Illustration: Tungsten lamp of Dr. Hans Kuzel.]

New Arc Lamps.

For large spaces indoors and for out of doors the arc-lamp 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 2-1/2 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.

[Illustration: Hewitt mercury-vapor lamp.]

Hewitt Mercury-Vapor Lamp.

From quite another side Mr. Peter Cooper Hewitt enters the field of
light production, utilizing the glow of a vapor 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.

From a brief consideration of illuminants let us pass to a rapid survey
of 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.

Steels for Strength.

In 1781 Professor Torbern Bergman, of the University of Upsala, in
Sweden, showed that steel mainly differs from 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.

[Illustration: Pearlite, magnified about 750 diameters.]

[Illustration: Steel containing more than nine-tenths of one per cent of
crystals of pearlite, surrounded by envelopes of cementite (Fe₃C).
Magnified 200 diameters.]

[Illustration: CLEANING CARS BY THE “VACUUM” METHOD.]

The Open Hearth Process.

Steel making by the open hearth process is chiefly due to the late Sir
William Siemens. In a gas producer he gave 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.

[Illustration: Open hearth furnace.]

The Gayley Dry-Blast Process.

A remarkable improvement in blast-furnace practice, cheapening cast or
pig-iron, and therefore lowering the 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.

Steels to Order.

What is chiefly sought in steel is tensile strength, next in 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.

Heat Treatment.

While the chemical composition of a steel is of prime 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.

Tempering and Annealing.

For rock drills, cold chisels, milling and other tools it is necessary
to use steel carefully tempered, so that 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.

Steel for Railroad Rails.

In another chapter of this book a word is said as to the form of rails
at which Mr. P. H. Dudley has arrived as the 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.

Invar: A Steel Invariable in Dimensions Whether Warmed or Cooled.

While the great strength of steel makes it of pre-eminent value in the
arts, steel in the huge dimensions of modern roofs and bridges has the
demerit of expanding with heat and contracting with cold in a
troublesome degree. A 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.

Manganese Steel.

The magnetic properties of steel, to-day of supreme 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.

High-Speed Tool Steels.

Until 1868, the steel tools used in lathes and drills, planers and so
on, were limited to the moderate pace at 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.

Alloys for Electro-Magnets.

In electrical art the alloy employed for electro-magnets should be
permeable by magnetism fully and easily, 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.

Magnetic Alloys of Non-Magnetic Ingredients.

We have so long been accustomed to thinking that there must be iron in
everything magnetic that we hear with astonishment that metals each
insusceptible of 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.

Anti-Friction Alloys.

We have briefly glanced at recent progress in the art of alloying in so
far as it has produced steels of new 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.

Influence of Minute Admixtures.

We have seen how remarkably the properties of iron are affected by
minute additions of carbon which may be assumed to enter into chemical
union with the metal. The 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. 3_s._ 6_d._ 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. 21_s._

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. 25_s._

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. 5_s_. $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. 16_s._

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. 16_s._

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.

Jena Glass.

As in the case of the aluminium bronzes and nickel steels, 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.

[Illustration: 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.

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

[Illustration: Bliss process of shell making.]

Power Presses in Metal Working.

From glass let us now turn to metals. It is their tenacity that chiefly
gives them value; this tenacity is usually 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.

[Illustration: Mandolin pressed in aluminium.]

[Illustration: Pressed Seamless pitcher.]

[Illustration: 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.

[Illustration: Range front pressed from sheet steel.]

[Illustration: Pressed paint tube and cover.]

Non-Conductors of Heat.

In a vast manufactory of steel cars, of steel structural forms, steam
has to be conveyed long distances from the 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                      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.

Norwegian Cooking Box.

The costliness of electric heat forbids the housekeeper from using much
of it. Her main source of heat must 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.

[Illustration: Norwegian cooker.]

Aladdin oven.

On the same principle is the Aladdin oven, invented by the 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.

[Illustration: Aladdin Oven.]

Matter Impressed by Its History.

Every property of matter seems universal. The best non-conductor of heat
transmits a little heat; the best 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.

Magnetization.

That matter virtually remembers its impressions is plain 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.

[Illustration: Mayer’s floating magnets.]

The Crystal Foreshadows the Plant.

One of the remarkable attributes of a crystal is its ability to grow and
act as a unit, as if it had a life of its own, despite the evident
variety and great number of its parts. 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.

[Illustration: A

Alum crystal.

B

After a part has been broken off.

C

Restored by immersion in alum solution.

From photographs by Herr Hugo Schmidt, Hackley School, Tarrytown, N. Y.]

During Long Periods Minute Influences Become Telling.

Qualities of matter, much more simple, may now engage our attention.
First, then, let us note how minute influences, acting for long
stretches of time, may change 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.

[Illustration: Iron tube enclosing marble before and after deformation.]

[Illustration: Marble before 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.

Properties age after age have become more and more intimately known. 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.

Solids are not as Solid as They Seem.

In a northern winter we may observe in air almost still, the wasting
away of a large block of ice, so that during a week it loses a
considerable part of its bulk. The giving 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.

Every Property May be Universal.

Here we are reminded of a striking experiment by Faraday: exciting an
electro-magnet of gigantic 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.

Radium Reveals Properties Unknown Till Now.

While radio-activity may be a universal property of matter, to be
disclosed more and more as means of detection are refined and improved,
radium compounds 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.

[Illustration: 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.”

History of the Universe Rewritten in the Light of Radio-Activity.

Radio-activity has a vivid interest far beyond the laboratories of
chemists and physicians. One of the long standing puzzles of geology has
been to explain why the temperature of the earth has remained fairly
constant 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:--

Faraday’s Prophetic Views.

“If we now conceive a change as far beyond vaporization as that is above
fluidity, and then take into account the 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.

A child notices that his bedroom is smaller than the family parlor, that
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.

Foot and Cubit.

How the foot, our commonest measure, has descended to us 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.

The Metric System.

Here the Government of France took the lead; in 1791 it appointed as a
committee Lagrange, Laplace, Borda, 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.

Uses of Refined Measurement.

Lord Kelvin, a master in the art of measurement, an inventor of
electrical measuring instruments of the 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