COSMIC CRUCIBLES
"Shelter during Raids," marking the entrance to underground passages,
was a sign of common occurrence and sinister suggestion throughout
London during the war. With characteristic ingenuity and craftiness,
ostensibly for purposes of peace but with bomb-carrying capacity
as a prime specification, the Zeppelin had been developed by the
Germans to a point where it seriously threatened both London and
Paris. Searchlights, range-finders, and anti-aircraft guns, surpassed
by the daring ventures of British and French airmen, would have
served but little against the night invader except for its one
fatal defect--the inflammable nature of the hydrogen gas that kept
it aloft. A single explosive bullet served to transform a Zeppelin
into a heap of scorched and twisted metal. This characteristic
of hydrogen caused the failure of the Zeppelin raids.
Had the war lasted a few months longer, however, the work of American
scientists would have made our counter-attack in the air a formidable
one. At the signing of the armistice hundreds of cylinders of compressed
helium lay at the docks ready for shipment abroad. Extracted from
the natural gas of Texas wells by new and ingenious processes,
this substitute for hydrogen, almost as light and absolutely
uninflammable, produced in quantities of millions of cubic feet,
would have made the dirigibles of the Allies masters of the air. The
special properties of this remarkable gas, previously obtainable only
in minute quantities, would have sufficed to reverse the situation.
SOLAR HELIUM
Helium, as its name implies, is of solar origin. In 1868, when
Lockyer first directed his spectroscope to the great flames or
prominences that rise thousands of miles, sometimes hundreds of
thousands, above the surface of the sun, he instantly identified
the characteristic red and blue radiations of hydrogen. In the
yellow, close to the position of the well-known double line of
sodium, but not quite coincident with it, he detected a new line,
of great brilliancy, extending to the highest levels. Its similarity
in this respect with the lines of hydrogen led him to recognize
the existence of a new and very light gas, unknown to terrestrial
chemistry.
Many years passed before any chemical laboratory on earth was able
to match this product of the great laboratory of the sun. In 1896
Ramsay at last succeeded in separating helium, recognized by the same
yellow line in its spectrum, in minute quantities from the mineral
uraninite. Once available for study under electrical excitation in
vacuum tubes, helium was found to have many other lines in its
spectrum, which have been identified in the spectra of solar
prominences, gaseous nebulæ, and hot stars. Indeed, there is a
stellar class known as helium stars, because of the dominance of
this gas in their atmospheres.
[Illustration: Fig. 30. Solar prominences, photographed with the
spectroheliograph without an eclipse (Ellerman).
In these luminous gaseous clouds, which sometimes rise to elevations
exceeding half the sun's diameter, the new gas helium was discovered
by Lockyer in 1868. Helium was not found on the earth until 1896.
Since then it has been shown to be a prominent constituent of nebulæ
and hot stars.]
The chief importance of helium lies in the clue it has afforded to
the constitution of matter and the transmutation of the elements.
Radium and other radioactive substances, such as uranium, spontaneously
emit negatively charged particles of extremely small mass (electrons),
and also positively charged particles of much greater mass, known
as alpha particles. Rutherford and Geiger actually succeeded in
counting the number of alpha particles emitted per second by a
known mass of radium, and showed that these were charged helium
atoms.
To discuss more at length the extraordinary characteristics of
helium, which plays so large a part in celestial affairs, would
take us too far afield. Let us therefore pass to another case in
which a fundamental discovery, this time in physics, was first
foreshadowed by astronomical observation.
SUN-SPOTS AS MAGNETS
No archæologist, whether Young or Champollion deciphering the Rosetta
Stone, or Rawlinson copying the cuneiform inscription on the cliff
of Behistun, was ever faced by a more fascinating problem than that
which confronts the solar physicist engaged in the interpretation
of the hieroglyphic lines of sun-spot spectra. The colossal whirling
storms that constitute sun-spots, so vast that the earth would make
but a moment's scant mouthful for them, differ materially from
the general light of the sun when examined with the spectroscope.
Observing them visually many years ago, the late Professor Young,
of Princeton, found among their complex features a number of double
lines which he naturally attributed, in harmony with the physical
knowledge of the time, to the effect of "reversal" by superposed
layers of vapors of different density and temperature. What he
actually saw, however, as was proved at the Mount Wilson Observatory
in 1908, was the effect of a powerful magnetic field on radiation,
now known as the Zeeman effect.
[Illustration: Fig. 31. The 150-foot tower telescope of the Mount
Wilson Observatory.
An image of the sun about 16 inches in diameter is formed in the
laboratory at the base of the tower. Below this, in a well extending
80 feet into the earth, is the powerful spectroscope with which
the magnetic fields in sun-spots and the general magnetic field
of the sun are studied.]
Faraday was the first to detect the influence of magnetism on light.
Between the poles of a large electromagnet, powerful for those
days (1845), he placed a block of very dense glass. The plane of
polarization of a beam of light, which passed unaffected through
the glass before the switch was closed, was seen to rotate when the
magnetic field was produced by the flow of the current. A similar
rotation is now familiar in the well-known tests of sugars--lævulose
and dextrose--which rotate plane-polarized light to left and right,
respectively.
But in this first discovery of a relationship between light and
magnetism Faraday had not taken the more important step that he
coveted--to determine whether the vibration period of a light-emitting
particle is subject to change in a magnetic field. He attempted
this in 1862--the last experiment of his life. A sodium flame was
placed between the poles of a magnet, and the yellow lines were
watched in a spectroscope when the magnet was excited. No change
could be detected, and none was found by subsequent investigators
until Zeeman, of Leiden, with more powerful instruments made his
famous discovery, the twenty-fifth anniversary of which has recently
been celebrated.
[Illustration: Fig. 32. Pasadena Laboratory of the Mount Wilson
Observatory.
Showing the large magnet (on the left) and the spectroscopes used
for the study of the effect of magnetism on radiation. A single line
in the spectrum is split by the magnetic field into from three to
twenty-one components, as illustrated in Fig. 34. The corresponding
lines in the spectra of sun-spots are split up in precisely the
same way, thus indicating the presence of powerful magnetic fields
in the sun.]
His method of procedure was similar to Faraday's, but his magnet and
spectroscope were much more powerful, and a theory due to Lorentz,
predicting the nature of the change to be expected, was available
as a check on his results. When the current was applied the lines
were seen to widen. In a still more powerful magnetic field each
of them split into two components (when the observation was made
along the lines of force), and the light of the components of each
line was found to be circularly polarized in opposite directions.
Strictly in harmony with Lorentz's theory, this splitting and
polarization proved the presence in the luminous vapor of exactly such
negatively charged electrons as had been indicated there previously
by very different experimental methods.
In 1908 great cyclonic storms, or vortices, were discovered at
the Mount Wilson Observatory centring in sun-spots. Such whirling
masses of hot vapors, inferred from Sir Joseph Thomson's results
to contain electrically charged particles, should give rise to a
magnetic field. This hypothesis at once suggested that the double
lines observed by Young might really represent the Zeeman effect.
The test was made, and all the characteristic phenomena of radiation
in a magnetic field were found.
Thus a great physical experiment is constantly being performed
for us in the sun. Every large sunspot contains a magnetic field
covering many thousands of square miles, within which the spectrum
lines of iron, manganese, chromium, titanium, vanadium, calcium,
and other metallic vapors are so powerfully affected that their
widening and splitting can be seen with telescopes and spectroscopes
of moderate size.
THE TOWER TELESCOPE
Both of these illustrations show how the physicist and chemist,
when adequately armed for astronomical attack, can take advantage
in their studies of the stupendous processes visible in cosmic
crucibles, heated to high temperatures and influenced, as in the
case of sun-spots, by intense magnetic fields. Certain modern
instruments, like the 60-foot and 150-foot tower telescopes on
Mount Wilson, are especially designed for observing the course
of these experiments. The second of these telescopes produces at
a fixed point in a laboratory an image of the sun about 16 inches
in diameter, thus enlarging the sun-spots to such a scale that
the magnetic phenomena of their various parts can be separately
studied. This analysis is accomplished with a spectroscope 80 feet
in length, mounted in a subterranean chamber beneath the tower. The
varied results of such investigations cannot be described here.
Only one of them may be mentioned--the discovery that the entire sun,
rotating on its axis, is a great magnet. Hence we may reasonably
infer that every star, and probably every planet, is also a magnet,
as the earth has been known to be since the days of Gilbert's "De
Magnete." Here lies one of the best clues for the physicist who
seeks the cause of magnetism, and attempts to produce it, as Barnett
has recently succeeded in doing, by rapidly whirling masses of
metal in the laboratory.
[Illustration: Fig. 33. Sun-spot vortex in the upper hydrogen
atmosphere. (Benioff).
Photographed with the spectroheliograph. The electric vortex that
causes the magnetic field of the spot lies at a lower level, and
is not shown by such photographs.]
Perhaps a word of caution should be interpolated at this point.
Solar magnetism in no wise accounts for the sun's gravitational
power. Indeed, its attraction cannot be felt by the most delicate
instruments at the distance of the earth, and would still be unknown
were it not for the influence of magnetism on light.
Auroras, magnetic storms, and such electric currents as those that
recently deranged several Atlantic cables are due, not to the magnetism
of the sun or its spots, but probably to streams of electrons, shot
out from highly disturbed areas of the solar surface surrounding
great sun-spots, traversing ninety-three million miles of the ether
of space, and penetrating deep into the earth's atmosphere. These
striking phenomena lead us into another chapter of physics, which
limitations of space forbid us to pursue.
STELLAR CHEMISTRY
Let us turn again to chemistry, and see where experiments performed
in cosmic laboratories can serve as a guide to the investigator.
A spinning solar tornado, incomparably greater in scale than the
devastating whirlwinds that so often cut narrow paths of destruction
through town and country in the Middle West, gradually gives rise
to a sun-spot. The expansion produced by the centrifugal force at
the centre of the storm cools the intensely hot gases of the solar
atmosphere to a point where chemical union can occur. Titanium
and oxygen, too hot to combine in most regions of the sun, join
to form the vapor of titanium oxide, characterized in the sunspot
spectrum by fluted bands, made up of hundreds of regularly spaced
lines. Similarly magnesium and hydrogen combine as magnesium hydride
and calcium and hydrogen form calcium hydride. None of these compounds,
stable at the high temperatures of sun-spots, has been much studied
in the laboratory. The regions in which they exist, though cooler
than the general atmosphere of the sun, are at temperatures of
several thousand degrees, attained in our laboratories only with
the aid of such devices as powerful electric furnaces.
[Illustration: Fig. 34. Splitting of spectrum lines by a magnetic
field (Babcock).
The upper and lower strips show lines in the spectrum of chromium,
observed without a magnetic field. When subjected to the influence
of magnetism, these single lines are split into several components.
Thus the first line on the right is resolved by the field into
three components, one of which (plane polarized) appears in the
second strip, while the other two, which are polarized in a plane
at right angles to that of the middle component, are shown on the
third strip. The next line is split by the magnetic field into
twelve components, four of which appear in the second strip and
eight in the third. The magnetic fields in sun-spots affect these
lines in precisely the same way.]
It is interesting to follow our line of reasoning to the stars,
which differ widely in temperature at various stages in their
life-cycle.[*] A sun-spot is a solar tornado, wherein the intensely
hot solar vapors are cooled by expansion, giving rise to the compounds
already named. A red star, in Russell's scheme of stellar evolution,
is a cooler sun, vast in volume and far more tenuous than atmospheric
air when in the initial period of the "giant" stage, but compressed
and denser than water in the "dwarf" stage, into which our sun has
already entered as it gradually approaches the last phases of its
existence. Therefore we should find, throughout the entire atmosphere
of such stars, some of the same compounds that are produced within
the comparatively small limits of a sun-spot. This, of course,
on the correct assumption that sun and stars are made of the same
substances. Fowler has already identified the bands of titanium
oxide in such red stars as the giant Betelgeuse, and in others
of its class. It is safe to predict that an interesting chapter
in the chemistry of the future will be based upon the study of
such compounds, both in the laboratory and under the progressive
temperature conditions afforded by the countless stellar "giants"
and "dwarfs" that precede and follow the solar state.
[Footnote *: See Chapter II.]
[Illustration: Fig. 35. Electric furnace in the Pasadena laboratory
of the Mount Wilson Observatory.
With which the chemical phenomena observed in sun-spots and red
stars are experimentally imitated.]
ASTROPHYSICAL LABORATORIES
It is precisely in this long sequence of physical and chemical
changes that the astrophysicist and the astrochemist can find the
means of pushing home their attack. It is true, of course, that
the laboratory investigator has a great advantage in his ability
to control his experiments, and to vary their progress at will.
But by judicious use of the transcendental temperatures, far out
ranging those of his furnaces, and extreme conditions, which he
can only partially imitate, afforded by the sun, stars, and nebulæ,
he may greatly widen the range of his inquiries. The sequence of
phenomena seen during the growth of a sun-spot, or the observation
of spots of different sizes, and the long series of successive
steps that mark the rise and decay of stellar life, resemble the
changes that the experimenter brings about as he increases and
diminishes the current in the coils of his magnet or raises and
lowers the temperature of his electric furnace, examining from
time to time the spectrum of the glowing vapors, and noting the
changes shown by the varying appearance of their lines.
[Illustration: Fig. 36. Titanium oxide in red stars.
The upper spectrum is that of titanium in the flame of the electric
arc, where its combination with oxygen gives rise to the bands of
titanium oxide (Fowler). The lower strip shows the spectrum of
the red star Mira (Omicron Ceti), as drawn by Cortie at Stonyhurst.
The bands of titanium oxide are clearly present in the star.]
[Illustration: Fig. 37. Titanium oxide in sun-spots.
The upper strip shows a portion of the spectrum of a sun-spot
(Ellerman); the lower one the corresponding region of the spectrum
of titanium oxide (King). The fluted bands of the oxide spectrum
are easily identified in the spot, where they indicate that titanium
and oxygen, too hot to combine in the solar atmosphere, unite in the
spot because of the cooling produced by expansion in the vortex.]
Astronomical observations of this character, it should be noted, are
most effective when constantly tested and interpreted by laboratory
experiment. Indeed, a modern astrophysical observatory should be
equipped like a great physical laboratory, provided on the one hand
with telescopes and accessory apparatus of the greatest attainable
power, and on the other with every device known to the investigator
of radiation and the related physical and chemical phenomena. Its
telescopes, especially designed with the aims of the physicist and
chemist in view, bring images of sun, stars, nebulæ, and other
heavenly bodies within the reach of powerful spectroscopes, sensitive
bolometers and thermopiles, and the long array of other appliances
available for the measurement and analysis of radiation. Its electric
furnaces, arcs, sparks, and vacuum tubes, its apparatus for increasing
and decreasing pressure, varying chemical conditions, and subjecting
luminous gases and vapors to the influence of electric and magnetic
fields, provide the means of imitating celestial phenomena, and of
repeating and interpreting the experiments observed at the telescope.
And the advantage thus derived, as we have seen, is not confined
to the astronomer, who has often been able, by making fundamental
physical and chemical discoveries, to repay his debt to the physicist
and chemist for the apparatus and methods which he owes to them.
NEWTON AND EINSTEIN
Take, for another example, the greatest law of physics--Newton's
law of gravitation. Huge balls of lead, as used by Cavendish, produce
by their gravitational effect a minute rotation of a delicately
suspended bar, carrying smaller balls at its extremities. But no
such feeble means sufficed for Newton's purpose. To prove the law
of gravitation he had recourse to the tremendous pull on the moon
of the entire mass of the earth, and then extended his researches
to the mutual attractions of all the bodies of the solar system.
Later Herschel applied this law to the suns which constitute double
stars, and to-day Adams observes from Mount Wilson stars falling
with great velocity toward the centre of the galactic system under
the combined pull of the millions of objects that compose it. Thus
full advantage has been taken of the possibility of utilizing the
great masses of the heavenly bodies for the discovery and application
of a law of physics and its reciprocal use in explaining celestial
motions.
[Illustration: Fig. 38. The Cavendish experiment.
Two lead balls, each two inches in diameter, are attached to the
ends of a torsion rod six feet long, which is suspended by a fine
wire. The experiment consists in measuring the rotation of the
suspended system, caused by the gravitational attraction of two
lead spheres, each twelve inches in diameter, acting on the two
small lead balls.]
Or consider the Einstein theory of relativity, the truth or falsity
of which is no less fundamental to physics. Its inception sprang from
the Michelson-Morley experiment, made in a laboratory in Cleveland,
which showed that motion of the earth through the ether of space could
not be detected. All of the three chief tests of Einstein's general
theory are astronomical--because of the great masses required to
produce the minute effects predicted: the motion of the perihelion
of Mercury, the deflection of the light of a star by the attraction
of the sun, and the shift of the lines of the solar spectrum toward
the red--questions not yet completely answered.
But it is in the study of the constitution of matter and the evolution
of the elements, the deepest and most critical problem of physics
and chemistry, that the extremes of pressure and temperature in the
heavenly bodies, and the prevalence of other physical conditions not
yet successfully imitated on earth, promise the greatest progress.
It fortunately happens that astrophysical research is now at the
very apex of its development, founded as it is upon many centuries
of astronomical investigation, rejuvenated by the introduction
into the observatory of all the modern devices of the physicist,
and strengthened with instruments of truly extraordinary range
and power. These instruments bring within reach experiments that
are in progress on some minute region of the sun's disk, or in
some star too distant even to be glimpsed with ordinary telescopes.
Indeed, the huge astronomical lenses and mirrors now available
serve for these remote light-sources exactly the purpose of the
lens or mirror employed by the physicist to project upon the slit
of his spectroscope the image of a spark or arc or vacuum tube
within which atoms and molecules are exposed to the influence of
the electric discharge. The physicist has the advantage of complete
control over the experimental conditions, while the astrophysicist
must observe and interpret the experiments performed for him in
remote laboratories. In actual practice, the two classes of work
must be done in the closest conjunction, if adequate utilization
is to be made of either. And this is only natural, for the trend
of recent research has made clear the fact that one of the three
greatest problems of modern astronomy and astrophysics, ranking
with the structure of the universe and the evolution of celestial
bodies, is the constitution of matter. Let us see why this is so.
TRANSMUTATION OF THE ELEMENTS
The dream of the alchemist was to transmute one element into another,
with the prime object of producing gold. Such transmutation has been
actually accomplished within the last few years, but the process
is invariably one of disintegration--the more complex elements
being broken up into simpler constituents. Much remains to be done
in this same direction; and here the stars and nebulæ, which show
the spectra of the elements under a great variety of conditions,
should help to point the way. The progressive changes in spectra,
from the exclusive indications of the simple elements hydrogen,
helium, nitrogen, possibly carbon, and the terrestrially unknown
gas nebulium in the gaseous nebulæ, to the long list of familiar
substances, including several chemical compounds, in the red stars,
may prove to be fundamentally significant when adequately studied
from the standpoint of the investigator of atomic structure. The
existing evidence seems to favor the view, recently expressed by
Saha, that many of these differences are due to varying degrees
of ionization, the outer electrons of the atoms being split off
by high temperature or electrical excitation. It is even possible
that cosmic crucibles, unrivalled by terrestrial ones, may help
materially to reveal the secret of the formation of complex elements
from simpler ones. Physicists now believe that all of the elements are
compounded of hydrogen atoms, bound together by negative electrons.
Thus helium is made up of four hydrogen atoms, yet the atomic weight
of helium (4) is less than four times that of hydrogen (1.008).
The difference may represent the mass of the electrical energy
released when the transmutation occurred.
[Illustration: Fig. 39. The Trifid Nebula in Sagittarius (Ritchey).
The gas "nebulium," not yet found on the earth, is the most
characteristic constituent of irregular nebulæ. Nebulium is recognized
by two green lines in its spectrum, which cause the green color of
nebulæ of the gaseous type.]
Eddington has speculated in a most interesting way on this possible
source of stellar heat in his recent presidential address before the
British Association for the Advancement of Science (see _Nature_,
September 2, 1920). He points out that the old contraction hypothesis,
according to which the source of solar and stellar heat was supposed
to reside in the slow condensation of a radiating mass of gas under
the action of gravity, is wholly inadequate to explain the observed
phenomena. If the old view were correct, the earlier history of
a star, from the giant stage of a cool and diaphanous gas to the
period of highest temperature, would be run through within eighty
thousand years, whereas we have the best of evidence that many
thousands of centuries would not suffice. Some other source of energy
is imperatively needed. If 5 per cent of a star's mass consists
originally of hydrogen atoms, which gradually combine in the slow
process of time to form more complex elements, the total heat thus
liberated would more than suffice to account for all demands, and
it would be unnecessary to assume the existence of any other source
of heat.
[Illustration: Fig. 40. Spiral nebula in Ursa Major (Ritchey).
Luminous matter, in every variety of physical and chemical state,
is available for study in the most diverse celestial objects, from
the spiral and irregular nebulæ through all the types of stars.
Doctor van Maanen's measures of the Mount Wilson photographs indicate
outward motion along the arms of spiral nebulæ, while the spectroscope
shows them to be whirling at enormous velocities.]
COSMIC PRESSURES
This, it may fairly be said, is very speculative, but the fact
remains that celestial bodies appear to be the only places in which
the complex elements may be in actual process of formation from their
known source--hydrogen. At least we may see what a vast variety
of physical conditions these cosmic crucibles afford. At one end of
the scale we have the excessively tenuous nebulæ, the luminosity of
which, mysterious in its origin, resembles the electric glow in our
vacuum tubes. Here we can detect only the lightest and simplest of
the elements. In the giant stars, also extremely tenuous (the density
of Betelgeuse can hardly exceed one-thousandth of an atmosphere) we
observe the spectra of iron, manganese, titanium, calcium, chromium,
magnesium, vanadium, and sodium, in addition to titanium oxide.
The outer part of these bodies, from which light reaches us, must
therefore be at a temperature of only a few thousand degrees, but
vastly higher temperatures must prevail at their centres. In passing
up the temperature curve more and more elements appear, the surface
temperature rises, and the internal temperature may reach millions
of degrees. At the same time the pressure within must also rise,
reaching enormous figures in the last stages of stellar life. Cook
has calculated that the pressure at the centre of the earth is
between 4,000 and 10,000 tons per square inch, and this must be
only a very small fraction of that attained within larger celestial
bodies. Jeans has computed the pressure at the centre of two colliding
stars as they strike and flatten, and finds it may be of the order
of 1,000,000,000 tons per square inch--sufficient, if their diameter
be equal to that of the sun--to vaporize them 100,000 times over.
Compare these pressures with the highest that can be produced on
earth. If the German gun that bombarded Paris were loaded with a
solid steel projectile of suitable dimensions, a muzzle velocity
of 6,000 feet per second could be reached. Suppose this to be fired
into a tapered hole in a great block of steel. The instantaneous
pressure, according to Cook, would be about 7,000 tons per square
inch, only 1/150000 of that possible through the collision of the
largest stars.
[Illustration: Fig. 41. Mount San Antonio as seen from Mount Wilson.
Michelson is measuring the velocity of light between stations on
Mount Wilson and Mount San Antonio. Astronomical observations afford
the best means, however, of detecting any possible difference between
the velocities of light of different colors. From studies of variable
stars in the cluster Messier 5 Shapley concludes that if there is
any difference between the velocities of blue and yellow light
in free space it cannot exceed two inches in one second, the time
in which light travels 186,000 miles.]
Finally, we may compare the effects of light pressure on the earth
and stars. Twenty years ago Nichols and Hull succeeded, with the
aid of the most sensitive apparatus, in measuring the minute
displacements produced by the pressure of light. The effect is
so slight, even with the brightest light-sources available, that
great experimental skill is required to measure it. Yet in the
case of some of the larger stars Eddington calculates that one-half
of their mass is supported by radiation pressure, and this against
their enormous gravitational attraction. In fact, if their mass
were as great as ten times that of the sun, the radiation pressure
would so nearly overcome the pull of gravitation that they would
be likely to break up.
But enough has been said to illustrate the wide variety of experimental
devices that stand at our service in the laboratories of the heavens.
Here the physicist and chemist of the future will more and more
frequently supplement their terrestrial apparatus, and find new
clues to the complex problems which the amazing progress of recent
years has already done so much to solve.
PRACTICAL VALUE OF RESEARCHES ON THE CONSTITUTION OF MATTER
The layman has no difficulty in recognizing the practical value
of researches directed toward the improvement of the incandescent
lamp or the increased efficiency of the telephone. He can see the
results in the greatly decreased cost of electric illumination
and the rapid extension of the range of the human voice. But the
very men who have made these advances, those who have succeeded
beyond all expectation in accomplishing the economic purposes in
view, are most emphatic in their insistence upon the importance
of research of a more fundamental character. Thus Vice-President
J. J. Carty, of the American Telephone and Telegraph Company, who
directs its great Department of Development and Research, and Doctor
W. J. Whitney, Director of the Research Laboratory of the General
Electric Company, have repeatedly expressed their indebtedness
to the investigations of the physicist, made with no thought of
immediate practical return. Faraday, studying the laws of electricity,
discovered the principle which rendered the dynamo possible. Maxwell,
Henry, and Hertz, equally unconcerned with material advantage,
made wireless telegraphy practicable. In fact, all truly great
advances are thus derived from fundamental science, and the future
progress of the world will be largely dependent upon the provision
made for scientific research, especially in the fields of physics
and chemistry, which underlie all branches of engineering.
The constitution of matter, therefore, instead of appealing as
a subject to research only to the natural philosopher or to the
general student of science, is a question of the greatest practical
concern. Already the by-products of investigations directed toward
its elucidation have been numerous and useful in the highest degree.
Helium has been already cited; X-rays hardly require mention; radium,
which has so materially aided sufferers from cancer, is still better
known. Wireless telephony and transcontinental telephony with wires
were both rendered possible by studies of the nature of the electric
discharge in vacuum tubes. Thus the "practical man," with his distrust
of "pure" science, need not resent investments made for the purpose
of advancing our knowledge of such fundamental subjects as physics
and chemistry. On the contrary, if true to his name, he should
help to multiply them many fold in the interest of economic and
commercial development.