there are the following layers in the earth's masses:--First,
the external, rigid and brittle layer; second, a layer under
such temperature and pressure that it is above its plastic
yield point and may be considered as a viscous fluid. The
pressure must continue to increase toward the center. We do not
know what is the temperature, but it is perfectly possible that
at a greater depth the earth may become rigid once more if the
effect of pressure in promoting solidity and rigidity
continues, as Bridgman tells me he thinks probable. We do not
even have to assume a change in the chemical composition of the
earth's substance, though it is perfectly allowable. This,
then, will be a third layer, once more rigid, perhaps extending
to the center and of very considerable thickness and capable of
accumulating strain from long periods. Blanketed as it would be
by thousands of meters of the first two layers, any change must
be relatively slow.
Kelvin in his computation of the age of the earth from cooling
assumed for the interior of the earth constant conditions. It
is now generally accepted that this is not probable, and that
whether it cooled from a gas or coagulated from planetesimals,
it became solid first at the center which then would be
hottest, and both Becker[3] and A. Holmes[4] assume an initial
temperature gradient. If that gradient were greater than the
gradient of steady flow the conditions of steady flow would be
approached most rapidly at the exterior, the loss of heat and
energy would be altogether from within and it is easy to
arrange for conditions mathematically in which almost all the
loss of energy would come from the very interior, near the
center. What will be the effect? A paradoxical one, if the part
outside the center is rigid enough to be self-sustaining. The
central core will become a gas!
[3] Bull. Geol. Soc. Am., Vol. 26, 1915, p. 197, etc.
[4] Geological Magazine, March and April, 1913.
This is so contrary to our ordinary experience and ideas, in
which loss of heat tends to change from gas to fluid and solid,
that we must look into it a little to make it sound reasonable.
The recent brilliant work of P. W. Bridgman (contrary to the
earlier speculations of Tammann) indicates that the effect of
increased pressure, at high temperature, makes a substance
solid and crystalline. Crowd any atoms close enough together,
and no matter how fast they expand or contract under the
influence of heat the crystalline atomic forces will get to
work when they are crowded within their range, and the closest
packing, hence that which will yield most to the pressure,
hence that which is likely to take place, is when they are all
regularly arranged facing the same way. Such an arrangement we
call crystalline. Just so when they want to pack the most
people into the car of an elevator they ask them to all face to
the front. Keep this metaphor a moment. Any one who should try
to penetrate such a crowd would find it a hard job. They would
offer a very effective rigidity. Now suppose them to sweat in
those confined quarters their fat away, their phlogiston, their
caloric. If the walls of the car remained rigid while the
individuals therein shrunk they might after a while be able to
turn around or even move around in a car. Such is then the
supposed condition of the atoms in the FOURTH, the central,
layer of the earth's crust. This assumes that the middle layer
is rigid and sustains itself, like the shell of a nut, as in
the figure, while within the atoms are in a less rigid
condition. That such a shell might be self-sustaining is
suggested by an experiment of Bridgman, who put a marble with a
gas bubble in it under a pressure of something like 150,000
pounds to the square inch without producing any perceptible
change.
As loss of energy from the earth's interior went on this
central core of gas would enlarge until the middle shell was
hardly self-supporting. Then, probably at some time of
astronomic strain when the earth's, orbit was extra elliptical,
it would collapse, in collapsing generate heat, and so stop the
process. The collapse would be transmitted to the viscous layer
which might be increased, motions set up in it, and so a
wrinkling of the outer thin crust on which we live.
Then there would be four layers to the earth like the butternut
of the figure. First, the inner kernel of gas; second, the hard
shell or endocarp; third, a viscous layer like the sarcocarp or
pulp, and outside of all the wrinkled crust of exocarp. If such
is the structure of the earth we may have in the very structure
of the earth itself a reason why from time to time there are
collapses of the middle layer leading to elevations of portions
of the outer rind, and marking off the chapters in geological
history, the lines between geological systems.
There are reasons in facts of observation for believing that
such is the structure of the earth, of which I have as yet said
nothing. We see the interior of a glass marble, I saw the
bubble in the interior of Bridgman's glass marble, how? By
waves, vibrations, which start from the sun or some other
source, and going through it reach my eye. Though the earth is
not penetrated by sunlight it is penetrated by the waves and
vibrations that start from that jar produced by a crack which
we call an earthquake. These vibrations can be received by that
eye of the geologist called a seismograph. The seismologist
tells us there are three kinds of waves sent out in an
earthquake. If you notice the explosion of a blast at a little
too close distance you will notice that you see it first, then
hear it, and then perhaps a little later a few chips of rock
may come flying past your ears. These three things correspond
somewhat to the three kinds of waves which spread forth from an
earthquake. But in the case of the explosion we see the blast
first, then hear later. The waves which produce the sensation
of sight are, we know, lateral disturbances, the waves which
produce the sensation of sound are waves of condensation, whose
motion is in the direction of their propagation and they come
later. In the case of the jars of earth, the reverse is true.
The first set of waves to arrive are the waves which are due to
compression--vibrations in the direction in which the waves are
produced--and correspond to sound waves. Later come waves which
are transverse sidewise disturbances of the solid mass of the
earth. As we can easily see, in an earthquake jar traveling
from the opposite end of the earth, there should be no
insurmountable difficulty in recognizing the jar, which is a
direct upthrow from one which would tilt it to the right or
left. Now there is a law of Laplace by which the velocity of
spread of sound waves through gas may be calculated. That this
law should hold at temperatures and pressures so high as those
that must exist in the middle of the earth is, of course, a
question, but it will be interesting to see how nearly the
actual velocity of about 10 kilometers a second compares with
the velocity which such waves should have in gas of a density
and under a pressure such as a gas near the center of the earth
must have. Using Oldham's figures (and they seem to be
confirmed by the recent investigations of E. Rudolph and S.
Szirtes[18]), we find that the time of transmission of these
first and fastest preliminary compression tremors is about
twice the velocity of such a jar according to Laplace's law in
as dense a mass of gas, provided the ratio of the specific heat
of a gas at constant pressure to that of a gas at constant
volume remains 1.4, which is for many substances. But as it is
1.6 for mercury the discrepancy is not more than I had
expected.
[5] Gerlands, "Beitrage zur Geophysik," XI., Band, 1 Heft,
1911, p. 132. "Das kolumbianische Erdbeben am 31 January,
1906."
The second preliminary tremors arriving later are due to the
lateral disturbance. Their propagation is much less rapid when
the point of origin is nearly opposite the point of receival.
In other words there is a core within the earth about 0.4 of
the radius in radius, in which according to Oldham, these
lateral waves have much less velocity. Now in a gas there is
less resistance to lateral displacement than in a solid, and
the less the resistance the less the velocity, so that this
fact fits in with the idea of a gaseous core perfectly. If
there is such n core, moreover, of less rigidity it would have
less refraction. Consequently waves not striking the border
above the angle of total reflection would be totally reflected,
and just as around a bubble there is a dark border where the
light does not get through so at a certain distance from the
source of an earthquake there would be a circle (it is really
about 140 degrees of arc away), where no second tremors would
be felt. Here again, though seismograph stations are as yet
few, fact and theory are apparently going to correspond.
The last type of earthquake waves follow around the outer layer
of the crust.
There is one farther line of verification to which I had
addressed myself. Is it likely that the loss of heat and energy
from the central nucleus, at the rate which we know at the
surface from a central nucleus of anything like 0.4 the radius
of the earth, would give a shrinkage of anything like the
amount indicated by the mountain ranges, in anything like the
time which we are led to assign on other grounds to the
geologic periods?
Rudski has also attempted to connect the shrinkage and age of
the earth. Both these methods depend on how fast the earth is
losing heat, that is on the geothermal gradient. Since at
present, owing to the apparently large but unknown contribution
of radioactivity to that gradient we know very little about
what the other portion is, it seems unwise to give any figures,
especially as almost all the numerical data are largely guess
work. It will, however, be fair to say that very long times for
the age of the earth seem to be indicated, nearer millions of
millions than millions unless the radius of the gaseous core
was mainly small or its rate of contraction with loss of
temperature high.
THE CASH VALUE OF SCIENTIFIC RESEARCH
BY PROFESSOR T. BRAILSFORD ROBERTSON
UNIVERSITY OF CALIFORNIA
THERE can be no doubt that the average man and woman in Europe
and America to-day professes a more or less nebulous feeling of
respect and admiration for the scientific investigator. This
feeling is not logical, for very few have ever met or seen a
scientist, fewer still have ever seen the inside of a
scientific laboratory, and hardly any have ever seen scientific
research in the making.
The average man in the street or man of affairs has no very
clear conception of what manner of man a "scientist" may be. No
especial significance attaches in his mind to the term. No
picture of a personality or his work arises in the imagination
when the word "scientist" is pronounced. More or less
indefinitely, I suppose, it is conceded by all that a scientist
is a man of vast erudition (an impression by the way which is
often strikingly incorrect) who leads a dreary life with his
head buried in a book or his eye glued to telescope or
microscope, or perfumed with those disagreeable odors which, as
everybody knows, are inseparably associated with chemicals. The
purpose of this life is not very clear, but doubtless a vague
feeling exists in the minds of most of us that people who are
willing to pursue such an unattractive career must be worthy of
admiration, for despite all the triumphs of commercialism,
humanity still loves idealism, even idealism which seems
objectless because it is incomprehensible.
From time to time the existence of the scientific man is
recalled to the popular mind by some extravagant headlines in
the daily press, announcing some utterly impossible "discovery"
or some extravagantly nonsensical dictum made by an alleged
"scientist." The "discovery" was never made, the dictum never
uttered, but no matter; to-morrow its place will be taken by
the latest political or matrimonial scandal, and the public,
with excellent good sense, will forget all about it.
From time to time, also, there creeps gradually into the public
consciousness a sense that SOMETHING HAS HAPPENED. Brief
notices appear in the press, at first infrequently and then
more frequently, and an article or two in the popular
monthlies. The public becomes languidly interested in a new
possibility and even discusses it, sceptically. Then of a
sudden we are awakened to the realization of a new power in
being. The X-ray, wireless telegraphy or the aeroplane has
become the latest "marvel of science," only to develop in a
very brief period into a commonplace of existence.
Many indeed are aware that we owe these "marvels" to scientific
research, but very few indeed, to the shame of our schools be
it spoken, have attained to the faintest realization of the
indubitable fact that we owe almost the entirety of our
material environment, and no small proportion of our social and
spiritual environment, to the labors of scientists or of their
spiritual brethren.
Long ago, in ages so remote that no record of them survives
save our heritage of labor well achieved, some pastoral savage,
more reflective and less practical than his brethren, took to
star-gazing and noting in his memory certain strange
coincidences. Doubtless he was chidden by his tribal leaders
who were hard-headed men of affairs, skilled in the
questionable art of imposing conventional behavior upon unruly
tribesmen. But he was an inveterate dreamer, this prehistoric
Newton and the fascination of the thing had gripped his mind.
In due time he was gathered to his fathers, but not before he
had passed on to a few chosen ones the peculiar coincidences he
had observed. And thus, from age to age coincidence was added
to coincidence and the result of all this "unpractical" labor
was, at long last, a calendar. Let who will attempt to estimate
the cash value of this discovery; I will not attempt the
impossible. I will merely ask you to picture to yourselves
humanity in the condition of the Australian Aboriginal or of
the South African Bushman; devoid of any means of estimating
time or season save by the daily passage of the sun, and I ask
you, "supposing that through some vast calamity, a calamity
greater even than the present war, humanity could at a stroke
evolve a calendar, would it be worth while?" I for one think it
would.
The evolution of the calendar is not an inapt illustration of
the methods of science, and of the part which it has played in
shaping the destiny of man. Out of the unregarded labors of
thousands of forgotten men, and a few whom we now remember, has
sprung every detail of that vast complex of machinery, method
and measurement in which to-day we live and move and have our
being. In all ages scientific curiosity guided by the
scientific discipline of thought has forced man into new and
more complex paths of progress. Lacking the spirit of research,
a nation or community is merely parasitic, living upon the
vital achievements of others, as Rome based her civilization
upon the civilization of the Greeks. Only an indefinite and
sterile refinement of the existing environment is possible
under such circumstances, and humanity stays stationary or
sinks back into the semibarbarism of the middle ages.
The few scattered students of nature of that day picked up the
clue to her secrets exactly as it fell from the hands of the
Greeks a thousand years before. The foundations of mathematics
were so well laid by them that our children learn their
geometry from a book written for the schools of Alexandria two
thousand years ago. Modern astronomy is the natural
continuation and development of the work of Hipparchus and of
Ptolemy; modern physics of that of Democritus and of
Archimedes; it was long before biological science outgrew the
knowledge bequeathed to us by Aristotle, by Theophrastus and by
Galen.[1]
[1] T. H. Huxley, "Science and Culture."
If, therefore, we ask ourselves what has been the value of
science to man, the answer is that its value is practically the
value of the whole world in which we find ourselves to-day, or,
at any rate, the difference between the value of our world and
that of a world inhabited by Neolithic savages.
The sweeping nature of this deduction may from its very
comprehensiveness fail to carry conviction to the reader. But
concrete illustrations of the value which scientific research
may add to our environment are not far to seek. They are
afforded in abundance by the dramatic achievements of the past
century of human progress, in which science has begun painfully
and haltingly to creep into its true place and achieve its true
function.
In the year 1813 many important events occurred. The power of
Napoleon was crumbling in that year and countless historians
have written countless pages describing innumerable events,
great and small, which accompanied that colossal downfall. But
one event of that year, of which we do not read in our
historical memoirs and school books was the discovery by Sir
Humphry Davy, in the humble person of a bookbinder's
apprentice, of the man who will probably stand out forever in
the history of science as the ideal scientific man--Michael
Faraday. The manner of this discovery is revealed by the
following conversation between Sir Humphry Davy and his friend
Pepys. "Pepys, what am I to do, here is a letter from a young
man named Faraday; he has been attending my lectures, and wants
me to give him employment at the Royal Institution--what can I
do?" "Do?" replied Pepys, "put him to wash bottles; if he
refuses he is good for nothing." "No, no," replied Davy; "we
must try him with something better than that." The result was,
that Davy engaged him to assist in the laboratory at weekly
wages.[2]
[2] J. Tyndall, "Faraday as a Discoverer."
Davy made many important discoveries, but none of his
discoveries was more important than his discovery of Faraday,
and of all the events which occurred in the year 1813, the
entry of Faraday into the Royal Institution was not the least
significant for humanity.
On the morning of Christmas day, 1821, Faraday called his wife
into his laboratory to witness, for the first time in the
history of man, the revolution of a magnet around an electric
current. The foundations of electromagnetics were laid and the
edifice was built by Faraday upon this foundation in the
fourteen succeeding years. In those years and from those
labors, the electro-motor, the motor generator, the electrical
utilization of water power, the electric car, electric
lighting, the telephone and telegraph, in short all that is
comprised in modern electrical machinery came actually or
potentially into being. The little rotating magnet which
Faraday showed his wife was, in fact, the first electric motor.
What was the cash value to humanity of those fourteen years of
labor in a laboratory?
According to the thirteenth census of the United States, the
value of the electrical machinery, apparatus and supplies
produced in this country alone, in 1909 was $221,000,000. In
1907, the value of the electric light and power stations in the
United States was $1,097,000,000, of the telephones
$820,000,000, and the combined income from these two sources
was $360,000,000. Nor does this represent a tithe of the
values, as yet barely realized, which these researches placed
at our disposal. Thus in its waterfalls, the United States is
estimated to possess 150,000,000 available horse-power, which
can only be realized through the employment of Faraday's
electro-motor. This corresponds, at the conservative figure of
$20 per horse-power per annum to a yearly income of
$3,000,000,000, corresponding at 4 per cent. interest to a
capital value of $75,000,000,0000.[3]
[3] M. T. Bogert, "The Function of Chemistry in the
Conservation of our National Resources," Journal of the
American Chemical Society, February, 1909.
Such was the Christmas gift which Michael Faraday presented to
the world in 1821.
Faraday died a poor man in 1867, neither for lack of
opportunity nor for lack of ability to grasp his opportunities,
but because as his pupil Tyndall tells us, he found it
necessary to choose between the pursuit of wealth and the
pursuit of science, and he deliberately chose the latter. This
is not a bad thing. It is perhaps as it should be, and as it
has been in the vast majority of cases. But another fact which
can not be viewed with like equanimity is that of all the
inexhaustible wealth which Faraday poured into the lap of the
world, not one millionth, not a discernible fraction, has ever
been returned to science for the furtherance of its aims and
its achievements, for the continuance of research.
There is no regular machinery for securing the permanent
endowment of research, and it is always and everywhere a barely
tolerated intruder. In the universities it crouches under the
shadow of pedagogy, and snatches its time and its materials
from the fragments which are left over when the all-important
business of teaching the young what others have accomplished
has been done. In commercial institutions it occasionally
pursues a stunted career, subject to all the caprices of
momentary commercial advantage and the cramped outlook of the
"practical man." The investigator in the employ of a commercial
undertaking is encouraged to be original, it is true, but not
to be too original. He must never transcend the "practical,"
that is to say, the infinitesimal rearrangement of the
preexisting. The institutions existing in the world which are
devoted to research and, research alone can almost be counted
on the fingers. The Solvay Institute in Brussels, the Nobel
Institute in Stockholm, the Pasteur Institute in France, the
Institute for Experimental Therapy at Frankfort, The Kaiser
Wilhelm Institutes at Berlin, The Imperial Institute for
Medical Research at Petrograd, the Biologisches Versuchsanstalt
at Vienna, the Biological Station at Naples, the Royal
Institution in London, the Wellcome Laboratories in England and
at Khartoum, the Smithsonian, Wistar, Carnegie and Rockefeller
Institutes in the United States; the list of research
institutes of important dimensions (excluding astronomical
observatories) is, I believe, practically exhausted by the
above enumeration, and many of them are woefully undermanned
and underequipped. At least two of them, the Solvay Institute
wholly, and the Frankfort Institute for Experimental Therapy in
part, owe their existence and continuance to scientific men,
Solvay and Ehrlich, who have contrived to combine the pursuit
of wealth and of science, and have dedicated the wealth thus
procured to the science that gave it birth.
In 1900 the value of the manufacturing industries in the United
States which had been developed from patented scientific
inventions was no less than $395,663,958 per annum,[4]
corresponding to a capital value of about $10,000,000,000. It
is impossible to arrive at any accurate estimate of the
proportion of this wealth which finds its way back to science
to provide equipment and subsistence for the investigator, who
is creating the wealth of the future. But the capital endowment
of the Rockefeller and Carnegie Institutes, the two wealthiest
institutes of research in the world is, according to the 1914
issue of Minerva, only $29,000,000. The total income (exclusive
of additions to endowments) of all the higher institutions of
learning in the United States in 1913, was only $90,000,000, of
which a minute percentage was expended in research.
[4] 12th census, Vol. 10, Part 4.
If science produces so much wealth, is there no contrivance
whereby we can cause a small fraction of this wealth to return
automatically to science and to furnish munitions of war for
fresh conquests of nature? A very small investment in research
often produces colossal returns. In 1911 the income of the
Kaiser Wilhelm Institute for Physical Chemistry was only
$21,000. In 1913 the income of the Institute for Experimental
Therapy at Frankfort, where "606" was discovered, was only
$20,000; that of the Imperial Institute for Medical Research at
Petrograd was $95,000, and that of the National Physical
Laboratory in England (not exclusively devoted to research) was
$40,000. Yet these are among the most famous research
institutions in the world and have achieved results of
world-wide fame and inestimable value both from a financial
standpoint and from the standpoint of the physical, moral and
spiritual welfare of mankind.