l
| McGILL UNIVERSITY PUBLICATIONs
M A series X PHYsics, - No. 11.
PHYSICS A HUNDRED YEARS AGO
A. S. EVE, C.B.E., D.Sc., F.R.S.
Macdonald Professor of Physics, McGill University. Möätreal, Canada.
Corresponding Member and Associate Editor.
REPRINTED proM THE Journal of THE FRANKLIN INsriruts
DECEMBER, 1921
PRESS OF
J. B. LIPPINCOTT COMPANY
1921
MONTREAL, 1922.

PHYSICS A HUNDRED YEARS AGO.*
BY
A. S. EVE, C.B.E., D.Sc., F.R.S.
Macdonald Professor of Physics, McGill University, Montreal, Canada.
Corresponding Member and Associate Editor.
A CENTURY ago science had recently lost three eminent men who
had notably advanced our knowledge of electricity, dynamics and
heat, Cavendish (1731–1815), Rumford (1753–1814), Watt
(1736–1819).
The steam engine had appeared and was used for pumping
mines, for locomotives and for the propulsion of ships; the
notable discovery had been made, to quote the contemporary words
of John Herschel, “A man's daily labour is about four pounds of
coal.” “Two pounds of coal would raise a strong man from the
valley of Chamounix to the top of Mt. Blanc.” “You can raise
seventy million pounds weight a foot high by a bushel of coals.” “
There had just begun that industrial revolution due to the use
of coal and iron, which, for better or worse, has in a century trans-
formed the world.
Every age regards its progress with a wholesome and justi-
fiable pride. The achievements of preceding generations are
dimmed in lustre by familiarity. The imagination is too feeble to
form an adequate conception of the marvels awaiting discovery,
ready to fall like ripe plums into the laps of successors. On the
other hand, recent discovery always stands out with a delightful
and refreshing vividness.
Now a hundred years ago people were thoroughly pleased with
their discoveries, no less than we are to-day. It is sufficient to
mention such successive discoveries as the spinning jenny (1768),
spinning frame (1769), cotton gin (1792); the discovery of the
planet Uranus (1780), the first air balloon (1783), and vac-
cination (1796).
Thanks to Newton and others, it was a just claim, in 1821,
that more scientific progress had been made in the preceding two
hundred years than in the whole previous history of mankind.
*Address at the Centenary Reunion of McGill University.
*The actual work done by a bushel of coals used in a steam engine was
called its duty, a useful term.
773
774 A. S. EVE. [J. F. I.
It is curious to read moreover the lamentations by Thomas
Young on the enormous amount of scientific literature and the
great variety of publications, which rendered it difficult or im-
possible to keep abreast with scientific discovery. How seriously
has this evil increased during the past hundred years, until we seem
doomed to be buried under our own records! And this trouble
must continually increase with time.
Mr. James McGill was an enlightened citizen of Montreal
with an interest in literary and scientific progress. It requires
but a small stretch of the imagination to conceive of our founder
sitting under an elm tree on Burnside Farm by the side of that
little brook, with its rustic bridge and lovers' walk, which flowed
past the spot where the Macdonald Physics Building now stands.
The valley of that brook is still visible in the back lane and ten-
nis court. And indeed in spring time, the brook itself revives
and floods our basement.
Imagine him seated there and reading the following fictitious
letter supposed to have been written about a century ago by a friend
of James McGill, an imaginary professor of natural philosophy
at the famous University of Glasgow, giving an account of a visit
to London and Paris, and describing to our founder what he saw
which was new and interesting in the scientific field. It is a matter
of regret to me that I cannot read this letter to you in the
good Scots tongue. *
From Professor Robin Angus,
The University of Glasgow,
(Undated).
To Mr. James McGill,
of Montreal.
Dear Mr. McGill,
I am now fortunate in writing to you to give my promised
account of a long projected visit to London and to Paris,
and my description of the progress of recent discovery in
natural philosophy.
I left Glasgow on the first of June and the roads were in good
condition so that we made a swift and agreeable journey. One
day indeed we traveled 59 miles in II 34 hours, including time
for baits'
Dec., I92I.] PHYSICS. 775
On my arrival at London I quickly went to the Royal Institu-
tion and called on Dr. Thomas Young. I was fortunate enough
to hear one of the 93 lectures which he is giving on natural phi-
losophy. These lectures are shortly to be published as a book, a
copy of which I will send you. His lectures were well illustrated
by skilful experiments.
You are aware that Sir Isaac Newton suggested that light con-
sisted of little bodies or corpuscles shot from the source of light
traveling “with an eel-like motion ” along straight lines. Now
Dr. T. Young will have none of this theory, but he agrees with
Huyghens that light travels with wave motion in some subtle and
all pervading medium which is called aether. Huyghens thought
that light consisted of waves with a motion of the aether to and
fro in the direction in which light traveled, but Doctor Young
points out, as did Newton, that light may be “one-sided ” or
polarized, so that it is essential to believe that the vibrations are
transverse or perpendicular to that direction in which light moves.
As indeed the French philosophers have very clearly proved.
Doctor Young has a large trough with a glass base, filled with
water, illuminated beneath; and with a large mirror he projects
upon a white screen the waves which are made upon the water
by one or more pointers fastened to vibrating rods. In this man-
ner he illustrates very clearly what is called the interference of
light, well enough known to Newton, but a stumbling block to his
corpusular theory.
At the Royal Institution I met also with Sir Humphrey Davy,
who has saved countless lives of miners by his safety lamp, where
the flame is surrounded by fine wire-screen, preventing prema-
ture explosion.
The great Corsican ogre, Napoleon, scourge of the world, is
newly dead. Yet in fairness it must be stated that he proved a
good friend to science. In the midst of the war between England
and France he gave, in spite of strong opposition, a great scientific
prize to an Englishman, Davy, for his discovery of potassium and
of sodium by electric separation. He caused a galaxy of Scientific
men to gather at Paris, and encouraged them in their work by
every means at his disposal. Napoleon was a man who certainly
knew that in science, too, “As a man sows, so shall he reap.”
I met at the Royal Institution a young assistant of Davy's
named Faraday who was full of insight and enthusiasm so that
776 A. S. EVE. [J. F. I.
he promises to go far. He was greatly interested in electri-
cal experiments.
You are familiar with electrical machines and Leyden jars,
lightning rods and Franklin's experiment with the kite, and how
he obtained electricity from the clouds. All these are well
described in a little book by Doctor Priestley which I sent you
last year. But, as the Hon. Mr. Cavendish wrote, “It must be
confessed that the whole science of electricity is yet in a very
imperfect state’”; or to quote my friend Doctor Young (p. 507),
“The phenomena of electricity are as amusing and popular in
their external form as they are intricate and abstruse in their
intimate nature.”
Suddenly there has come from Denmark a great burst of light,
which we owe to Hans Christian Oersted. This illustrious man
was born in 1777, and after passing with honours at school he
received free residence and a small scholarship awarded to needy
students. * After a distinguished career at Elers College he re-
ceived a Cappel Traveling Fellowship which enabled him to visit
the leading scientific men in Germany and France to his great
benefit as it now proves to ours. º
This plan of helping able students to secure a good university
education, and to visit other countries in order to appreciate
scientific progress, has much to commend it to other countries and
to all universities.
Many philosophers have endeavoured to deflect a magnet with
electricity, using an electrical machine with open circuit. Now
Oersted was lecturing to his advanced students and he discovered,
his class being there and then assembled, that with an electric
battery and a closed circuit he could cause a current of electricity
to deflect a magnet. Not when the wire is perpendicular to the
needle, but when parallel. This influence will pass through wood
and water and mercury and metal plates, excepting iron, so that the
influence of the electric current on a magnetic pole is as it were in
circles around the wire. Already Schweigger, at Halle, has invented
a measurer of electric current called the Astatic galvanometer,
where two equal magnetic needles pointing opposite ways have
* “A Familiar Guide to the Study of Electricity,” 4th ed., 1786. (J. John-
son, London.) -*
*Nature, p. 492, 16 June, IQ2I.
Dec., IQ2I.] PHYSICS. * 777
been deflected by a current passing in a coil of wire round one
needle, a most sensitive arrangement. --
Davy, using the great battery of 2000 cells of zinc and copper
at the Royal Institution, has passed an arc between two carbons
giving a most brilliant light. Now this arc he has deflected with
a magnet, showing that as a current in a circuit will deflect a
magnet so will the magnet deflect the circuit if and when a current
passes in it. Here then we have another example of the third
law of Newton that “action and reaction are equal and con-
trary.” Nay! Oersted himself hung up by a fine wire a small
battery and coil and deflected it with a magnet. Hence we now
have a new branch of science, my dear Mr. McGill, which we
may call electrodynamics or electromagnetics. The great M.
Ampère at Paris has made vast strides in this new subject.
And indeed I must pass over much that I would wish to tell you
that I saw and heard in London, and proceed with my visit to
Paris, which I reached safely after a troubled crossing over
the Channel.
In spite of the recent wars, most cordial relations have speedily
returned between scientific men of all countries.
I have met M. Ampère who, stimulated by Oersted's discovery,
nas extended it and proved that “two parallel and like-directed
currents attract each other, while two parallel currents of opposite
directions repel each other.”
It may be truly said that “the theory and experiment (of elec-
tric currents) seem as if they had leaped full-grown and full-armed
from the brain of the ‘Newton of Electricity.’ The theory is
perfect in form and unassailable in accuracy, and it is summed up
in a formula from which all the phenomena may be deduced and
which must always remain the fundamental formula of elec-
trodynamics.” “
But I must pass on, my dear Mr. McGill, to other branches of
natural philosophy. I must name the illustrious M. Chladni,
whom they call “the Father of Acoustics.” Him Napoleon sum.
moned to show his experiments on sound and gave a grant of
money towards the publication of his book. Galilei first experi-
mented with dust on vibrating metal plates struck by a chisel, but
Chladni made great improvemnts by using lycopodium dust with
sand. He separated thus the quiescent from the turbulent regions.
* Maxwell.
778 A. S. EVE. [J. F. I.
for as Faraday has explained, the light lycopodium dust is caught
in the whirlwinds of air and finally comes to rest below them,
while the heavier sand is driven to the nodes. I have been informed
that in the recent wars sand has been placed on a drum and the
direction of underground mining has been found by the displace-
ment of the sand on the top of the drum set vibrating by the distant
blows on the ground of the picks of the enemy. An ingenious
application of Chladni's figures'
Most interesting of all are the speculations about light founded
on the most ingenious experiments carried out by Fresnel and
Arago. They experiment with “one-sided ” or polarized light
and secure interference between two rays from the same source
polarized in the same plane, which cannot be done when the rays
are polarized at right angles. This is strong evidence for the wave
theory, but a challenge was given that a small round body like a
coin should have a bright spot in the center of its shadow from
a small bright source of light. In truth, and it should ! And the dif-
ficult experiment was triumphantly carried out by M. Fresnel !
Beautiful and interesting experiments have also been carried
out by M. Malus on the polarization of light, and splendid colour
effects have been achieved with the interference of polarized light
passing through crystals of mica, gypsum, or quartz.
The simplest interference experiment is to pass light through
a slit and hence through two slits close together. On a screen be-
hind you can perceive bright and dark bands alternating which
prove that two lights can make darkness, which seems impossible
with material things, but is readily explained with waves, for we
have all seen,.On a lake or pond, crests and troughs of waves cancel
one another.
There is great encouragement given to science in these days.
Thus the famous Euler received a grant of £2O,OOO in the last
century, and the British Government offered a prize of £20,000
for finding the longitude at sea within thirty miles.
Space has not permitted me to write of Fourier, a great mathe-
matician who has established most fundamental principles of the
flow of heat. His work, “Théorie de la Chaleur,” has in his own
lifetime passed into a classic.
But what shall I say of Laplace, author of “Mécanique
Céleste,” now seventy years old, comparable only with Newton,
who has been honoured by all political parties in the turbulent
Dec., IQ21.] PHYSICS. 779
periods passed by France in his long life. A man more admired
than loved perchance! Laplace has advanced the theory of tides,
explained the origin of the sun and planets from a nebula to its
present state, and proved that all bodies of the solar system are
stable, and may have been so for periods of vast antiquity.
In the spectrum of the sun, Wollaston (1802) and Fraun-
hofer (1815) have found a very great number of dark lines which
await explanation from succeeding generations. Here indeed we
have a great mystery!
But I fear, dear sir, that my letter has far outstripped your
patience. Your friends in Glasgow and in Scotland learn with
pleasure and interest your scheme for founding a College for the
Advancement of Learning in Montreal. Judging from what I have
seen in Scotland, in England and in France such an institution
may bring lasting lustre to your name, and yield priceless fruit
throughout succeeding ages.
Believe me, honoured sir,
Your most respectful servant,
ROB. ANGUs.
It must be admitted that historically the above letter will be
found wanting, for it purports to be written in 1821, by a “fake ’’
professor of Glasgow University, whereas we all know that our
founder died in 1813, eight years before McGill received its
charter in 1821. I am assured, however, by my colleague, Prof.
Cyrus Macmillan, that otherwise my conception of such a letter is
a sound one, and that James McGill was truly interested in science
as well as letters. He was himself a student or at least a matricu-
lant of Glasgow University, a fact which explains so much. You
will recall that he specially enjoined in his will that there
should be a Professor of Natural Philosophy, until such time as
there should be three chairs established in mathematics, natural
philosophy and astronomy.
To-day McGill has many professors of physics, a subject now
taught to all faculties. McGill has also several professors of
mathematics, but no astronomer, although he whom we might
venerate as our second founder, I name Sir William Macdonald,
donated a splendid region on the summit of Westmount for an
observatory, the land being still available, although we cannot hope
for “good seeing ” within the confines of a city yearly growing
780 A. S. EVE. II. F.I.
blacker with factory and engine smoke, largely preventable
and unnecessary.
As for the information conveyed in the fictitious letter, it is
gathered mainly from contemporary sources, and the lectures by
Dr. Thomas Young, afterward published as a Treatise on Natural
Philosophy, are a great mine of information. But a more valuable
source is Mrs. Kirstine Meyer's recent essay * on the Life of
Oersted. For in 1801 Oersted went to Weimar, Berlin, Gottin-
gen and Paris; he saw Ritter's electrical experiments and the very
first storage battery, copper plates with damp cardboard between,
which retained a charge for some time after it was connected to
a battery, capable also of generating a current after being charged.
In 1812 and 'I3 Oersted again visited Berlin and Paris, and
from autumn, 1822, to the summer of 1823 he visited Germany,
France and England, although he was full professor of natural
philosophy at Copenhagen at the time. I mention this because
we see here in the same man the great advantages of three notable
institutions or arrangements which I wish to advocate ardently for
Canada and elsewhere. For in the case of Oersted we see an
able but needy student obtaining free board and residence and a
scholarship as well, relieving him of money embarrassments and
securing him a sound and liberal education. Secondly, we find
him with a traveling fellowship which enabled him to appreciate
the work and progress of many scientific centres. Lastly, we find
him with a sabbatical year, relieved from the burden of teaching
and academic affairs, and given leisure to think and to investigate.
The scholarships, the traveling fellowship, the sabbatical year
were all fruitful. As a result Oersted founded electrodynamics,
for he proved that a coil of wire with a current round it was the
equivalent of a magnet.
This fundamental result, developed by Ampère, Faraday,
Maxwell, and many other co-workers, is the seed of the fruitful
results or harvest which you see around you to-day. I refer to
electric motors, lamps, dynamos, generators, electric irons,
cookers, bells, toasters, cleaners, and no less to telephones
and telegraphs.
We can rest assured that if you give due encouragement and
assistance to your quite ablest boys at schools, and to students and
professors at universities there are other and greater conquests of
* See Nature, 16, June, 1921.
Dec., 1921.] PHYSICS. 781
science of which we have little or no conception to-day, awaiting
discovery and development, and that you must not hesitate to
encourage pure research, at unpromising subjects even, rather
than endeavor too much to secure industrial research on a com-
mercial basis. The pioneer work is truly of the greater importance
though less likely to secure the appreciation of manufacturers, of
politicians, of practical men and of the public at large.
Here I must interpose a story. About fifteen years ago, one
of my predecessors, Professor John Cox, gave a lecture in this
theatre on the passage of electricity through rarefied gases com-
bined with some wonderful experiments, all with the skill and
eloquence of which he was and is still a master. Now Sir William
Macdonald was present and he remarked afterward, “How beauti-
ful and how useless!” Yet it is the study of those very phe-
nomena which has led to most notable recent developments in
radiology, for example the Coolidge tube, in long-distance and
guided telephone, in wireless telephony and telegraphy, particu-
larly by the use of the electronic valves.
But Sir William appears to have been himself a convert be-
fore his death. As donor to McGill of this Macdonald Physics
Building, as founder of the two Macdonald chairs of physics, he
was present at a lecture given by Sir Ernest Rutherford on some
of his recent work on radioactivity, and after the lecture Sir
William stated that “if all the money spent on the endowment
of physics at McGill had produced no other result but Ruther-
ford's work on radioactivity alone—the money would have been
well spent!” That verdict you will all endorse, with a fervent hope
that, although we can scarcely expect ever to rival that remarkable
outburst at McGill, of a new branch of physics, we may not merely
assist in the training of many thousands of young Canadians in the
foundations of science, but also hand on the torch of original
research and pioneer investigation in this place.
Oersted in 1822 and ’23 was not very enthusiastic about Ger-
man science. “Schweigger, at Halle, has brains, but is a reed
shaken with the wind. His experiments are not of much im-
portance; Kastner, at Erlangen, writes thick volumes compiled
with much toil but without all judgment. Yelin, at Munich, makes
indifferent experiments and lies much.” (Really, really, Yelin,
this is too bad!) “But I have found much that was instructive
with Fraunhofer, at Munich, so that I have been able to occupy
782 A. S. EVE. [J. F. I.
myself with benefit there for about a fortnight.” But he writes
to his wife from Paris in February, 1823. “My stay here grows
more and more interesting to me every day. The acquaintances
I have made grow every day more cordial and intimate.” He
saw Biot, Fresnel, Poillet, Ampère, Arago, Fourier, Dulong and
many others; such was the brilliant list of physicists there at work
at Paris. He had long discussions with Ampère on his famous
theory, still accepted, that magnetism consists of electric currents
in the molecules—electron currents or oscillations as we should
perhaps say to-day. Oersted adds, “On the Ioth I was at
Ampère's by appointment to see his experiments. He had invited
not a few—he had three considerable galvanic apparatus ready;
his instruments for showing his experiments are very complex;
but what happened? Hardly any of his experiments succeeded. He
is dreadfully confused and is equally unskilful as an experimenter
and as a debater.” This report is in strange contrast with the
written records of Ampère which Maxwell has described as
the work of the “Newton of Electricity,” “perfect in form and
unassailable in accuracy.” Perhaps Ampère had had the best
of an argument'
What then has been added in the last hundred years? Well,
the answer to that question will depend on whether you are a
so-called practical man or a theorist, whether you are most inter-
ested in the applications and practical achievements of physics or
in the great principles and theories which underlie the theory and
from which the practical applications necessarily arise.
The last hundred years have speeded up all human activities.
It now takes days for matter to cross the Atlantic instead of
weeks, as then; while messages are flashed across almost instan-
taneously. A hundred miles a day by coach or on horseback was
a strenuous journey, a thousand miles a day by rail is to-day
not formidable.
It has been argued with much force by R. A. Freeman in his
“Social Decay and Regeneration ” that mankind has suffered to
a terrible extent by the great access of power which science has
suddenly placed in its hands, and it may well be doubted if society
is yet fitted to receive fresh gifts of energy from the hands of
science. Moral development and social organization has lagged
behind scientific progress. Human nature is stable and ill fitted
to adapt itself to changes of the magnitude and variety of the last
Dec., 1921.] PHYSICS. 783
three-generations. The resultant instability of modern conditions
has shown itself to the greatest extent where the attempted
assimilation has been most rapid and ill digested. Petrograd
stands out as a prominent and inconceivable wreck, through the
mirage of a prostrate Russia.
When we turn our attention to the intellectual achievement of
physics we see a far more attractive picture. The last hundred
years have seen the almost complete development of the science
of electricity.
The great principle of the conservation of energy established
by the insight of Joule, Kelvin, Helmholtz and others, stands to-
gether with the Second Law of Thermodynamics as the main prop
of all physical conceptions. The isolation of the electron,
the discovery of its properties, experiments with alpha and
röntgen rays and immense developments in modern spectroscopy
are illuminating a vivid conception of the structure of the atom.
The present century is responsible for the new branch of physics,
and in this very place Rutherford delved deep and built high in
radioactivity, and we are all gathered together at a “veritable
shrine,” already venerated as such. We are passing to a new out-
look where energy becomes dominant, so that not only does mat-
ter appear to be energy, but space, linked with time from which it
is inseparable, is regarded as a continuum of energy mainly.
Most important of all is our revision of fundamental concep-
tions on a more comprehensive scale, in accord with the general
scheme of the universe of which we are denizens, embraced in the
fascinating and far-reaching Principle of Relativity.
Those only who have specialized in modern physics are
familiar with the strange elusive problems embraced in the
Quantum Theories of Energy.
An atomistic theory of matter is easy to conceive. A cor-
puscle of electricity, now called an electron, with well-marked
properties, electric and magnetic, is not too obscure. But bundles
of energy, or quanta, of magnitudes varying with and propor-
tional to the frequency of the propulsive electromagnetic vibra-
tions present formidable obstacles to the human intelligence, and
yet some such entities pervade modern research, and are to-day
most fruitful of actual philosophical progress.
I wonder what my successor, lecturing here one hundred
years hence, will be saying about relativity and about quanta!