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TW PATH of

SCIENCE

The Helix of History

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PATH of

CIENCE

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C. E. KENNETH MEES, D.Sc, F.R.S.

Vice President in charge of Research

Eastman Kodak Company

Rochester, New York

with the co-operation of
JOHN R. BAKER, M.A., D.PhiL, D.Sc.

Lecturer in Zoology in the
University of Oxford, England

New York: JOHN WILEY & SONS, Inc.
London: CHAPMAN & HALL, Limited

Charles Edward Kenneth Mees

This book or any part thereof must not
be reproduced in any form without
the written permission oj the publisher.

SECOND PRINTING, MARCH, 1947

PRINTED IN THE UNITED STATES OF AMERICA

"The present should retain its true proportion— a moment
between an infinite past and a hurrying future."

Time and Chance, Joan Evans
London, 1943

PREFACE

In 1943 I was invited to accept the Hitchcock professorship
at the University of California. Tlie Hitchcock professor
is expected to give a course of public lectures, and the subject
selected was the development of science and its relation to the
history of society. These lectures have been expanded into
this book with the purpose of presenting the development of
modern science against the background of history.

There is not room for a complete history of science in a
book of this type, but Chapters V, \^I, and VII are intended
to give an account of the gro^vth of ideas in the three major
sciences so that the reader can understand how the ideas of
modern science have developed.

My thanks are due to many friends for criticism and assist-
ance and especially to Dr. John R. Baker, w^io w^rote Chapter
VII, The Growth of Biological Ideas, and w^hose criticism of
the w^hole manuscript as it progressed has been most valuable.

Although the book is largely historical. Dr. Baker and I
are not professional historians of science. Dr. Baker is an
investigator in pure science, and I am a director of industrial
scientific research. It is hoped that our active participation
in the advance of science and technology has given us a view-
point that compensates for the lack of historical training.

C. E. K. Mees

Rochester, N. Y.
1946

CONTENTS

Chapter I. The Interpretation of History 1

Theories used for the interpretation of history-
unique events, cycles of civilization, and the idea of
progress.

Chapter II. The Helix of History 17

A resume of the prehistoric and early history of man,
pointing out that its structure, and especially that of the
history of Egypt, corresponds well with Petrie's theory
of the Revolutions of Civilization. The cycles of his-
tory, however, show a progressive increase in natural
knowledge so that the whole structure can be likened to
a helix, in which the vertical component represents the
growth of scientific knowledge, which increased rapidly
after the sixteenth century and then became the domi-
nant factor in the history of civilization.

Chapter III. The Method of Science 42

The epistemology of science, the methods used by
scientific men in observing, recording, and correlating
facts, the development of theories and scientific laws.

Chapter IV. The Development of the Scientific

Method 65

The early growth of science, beginning with its devel-
opment among the Greeks, the collapse in the Middle
Ages, and the rebirth in the Renaissance. The founda-
tion of the scientific societies at the end of the seven-
teenth century.

xii CONTENTS

Chapter V. The Growth of Physical Ideas 88

Chapter VI. The Growth of Chemical Ideas 119

Chapter VII. The Growth of Biological Ideas 144

(Written by Dr. John R. Baker)

Resume of the ideas of science and the methods by
which these ideas have been evolved. A brief account
of science intended to give a picture of the whole to an
educated man.

Chapter VIII. The Production of Scientific

Knowledge 173

The present organization for scientific research and
the developments in that organization likely to occur in
the near future.

Chapter IX. Applied Science and Industrial

Research 202

Organization of industrial scientific research and the
application of science to industry.

Chapter X. The Path of Science 225

The relation of science to society and the proposals
made for the application of science to the study of
sociology and politics. Resume of the path of science
as a whole in its relation to human society.

Index 237

Chapter I
THE INTERPRETATION OF HISTORY

Ever since men have ^viitten down their thoughts for the
benefit of their successors, they have tried to peer into the
future to form some idea of the events to come. For this
purpose, they have reHed upon auguries and upon observa-
tions of the stars; but the only method that is now generally
accepted is based on consideration of the past and expectation
that the future will follow the trends of the past, especially
the recent past.

Sometimes the conditions of human life continue un-
changed for long periods. Excavation of the cities of the
past, as well as their recorded history, shows us that often life
continued in those cities for generation after generation \vith
little change in the w^ay of living and even little change in
the material things— the tools and weapons used by the
people. During such periods of stability, the records show
a general belief that the stability would continue, that human
civilization is essentially a static system. As the Preacher
writes, 'The thing that hath been, it is that which shall be;
and that which is done is that which shall be done: and
there is no new thing under the sun." *

In attempting to look into the future by the use of our
records of the past, we are trying to discern in history some
general principles that we may expect to govern the order of
events. F. A. von Hayek considers it a contradiction in terms
to demand that history should become a theoretical science
and believes that the demand arises from the study of the
social sciences by those trained in the natural sciences who

* Ecclesiastes 1:9.

2 THE PATH GF SCIENCE

attempt to create a new science of society to satisfy their
own ideals. Von Hayek considers that the events of history
are "unique" and that "the creation and dissolution of the
Roman Empire or the Crusades, the French Revolution or
the Gro^vth of Modern Industry are unique complexes of
events which have helped to contribute the particular cir-
cumstances in which we live and whose explanation is there-
fore of great interest." *

However, while we may accept the view that the facts of
human history are unordered in detail, it is not impossible
that taken on a broad scale they may show some order. There
is nothing obviously false in assuming that human history
passes through cycles during ^vhich there is a change in some
factor in a definite direction. It would be possible, for in-
stance, for the length of human life to vary either progres-
sively or periodically as time continued. As far as the author
knows, there is no evidence for such a phenomenon; but if
the facts suggested it, there is no fundamental reason for re-
jecting it. H. G. Wells, indeed, holds that we are justified
in considering history as a whole to be a science. f He says,
"History is no exception amongst the sciences; as the gaps
fill in, the outline simplifies; as the outlook broadens, the
clustering multitude of details dissolve into general laws."
The nature of these laws is evidently of the first importance,
since upon them will depend the future that w^e may expect
and, therefore, any action that we may take to modify that
future. No pattern that we can detect in history can pos-
sibly foretell the future in detail; the past contains no maps
of the things to come. Nevertheless, history does fall into
patterns "as the outlook broadens," and these patterns may
be valuable for our guidance.

The views that men have held of the patterns of history
have had the greatest influence upon the ^vhole thought of

* F. A. von Hayek, "Scientism and the Study of Society, II," Eco-
nomica, N.S., 10, 34 (1943).

f H. G. Wells, Introduction to The Outline of History, London,
George Newnes, Ltd., 1920.

THE INTERPRETATION OF HISTORY 3

man. They have, indeed, been among those "ideas" that
have dominated the imagination and directed the actions of
mankind. After the destruction of the ancient world that
preceded the classical period— the world of Babylonia and
Egypt, Crete and the Hittite Empire, the world that was at
its height of prosperity in the fifteenth century before Christ-
there was a great period of darkness, in which the Hellenes
who had invaded western Asia Minor and Greece were slowly
advancing from their barbarian culture, much apparently as
the Saxons advanced slowly after they had destroyed the
Roman culture that they had found in Britain. In both cases,
the destruction of the old culture was extraordinarily com-
plete. In England, the very ditches had been abandoned, so
that when the cultivation of the fields was resumed, new lines
of drainage had to be established, a change that requires cen-
turies. In Greece, the art of writing appears to have been
lost, and the earliest writers of the reviving civilization bor-
rowed their alphabet from Semitic sources. This, however,
had its advantao^es. The Greeks started with a "clean slate."
As Bacon reminds us, they had no knowledge of antiquity,
and it is interesting to reflect that the classical Greeks spent
no time learning foreign languages. They were, in fact,
almost the only people of antiquity who did not devote them-
selves to that occupation, which today is considered such a
necessary discipline. The Babylonian youth had to learn
Sumerian, in which his classical books were written, and the
Roman regarded a knowledge of Greek as essential. But the
Greeks had no venerated classics, no holy books, no dead lan-
guages to master, no authorities to check their free specu-
lation.

Since the Greeks had no knowledge of any long period of
history, they had little material from ^vhich to get an idea of
a pattern in history. They recognized that man had pro-
gressed from a state of barbarism, and they ascribed his
progress to the invention and assistance of the gods. At the
same time, they held to the old legend of a past golden age,
a period of well-being and innocence from which man had

4 THE PATH OF SCIENCE

fallen, and thus they developed a theory of the rise and fall
of culture and civilization. In Plato's writings we find the
vie^v expressed that the world had been created as a perfect
world, but that it was not immortal and had in it the seeds
of decay, so that in time it would degenerate completely and
would be destroyed if the Creator did not intervene and start
the cycle again. The first stage of such a cycle would be the
golden age of legend, and the period in which the Greeks
found themselves they considered to be one of gradual decay
and degeneration. This view was in accordance w^ith the
whole attitude of the Greeks tow^ard life, an attitude of skepti-
cism and of pessimism. To a Greek philosopher, man was
a small figure in a great and turbulent universe, struggling
against the will of the pitiless gods who held his fate in their
hands and played with it for amusement; so that finally the
lesson was laid down tiiat a man must do all that he can and
that then, having failed, he must be prepared to suffer all
that he can suffer. This philosophy was expressed not only
by the philosophers themselves but it was stated even more
clearly by the tragic poets who had so great an influence on
Greek thought and who have retained that influence in the
thought of men to this day.

Plato's theory of world cycles became the orthodox theory
of history among the Greeks and passed from them to the
Romans. According to some of the follows ers of Pythagoras,
each cycle repeated to the minutest particular the course and
events of the preceding cycle. This theory w^as adopted by
the Stoics and is referred to by Marcus Aurelius in his Medi-
tations. He says that the "rational soul" contemplates the
grand revolutions of nature and the destruction and renewal
of the universe. So uniform is the course of history that a
man of forty years may know all the past and all the future.

There w^as a moment in Greek history w^hen the Greek
scholars stood on the edge of the discovery- of the method of
experimental science. For that moment they saw the possi-
bility of a different idea of history, and the Epicureans re-
jected the doctrine of a golden age and a subsequent degen-

THE INTERPRETATION OF HISTORY 5

eration and believed instead that the earliest condition of
men had been that of animals and that civilization had been
developed by the exercise of human intelligence. Expression
of this school is found in the work of Lucretius, the Roman
poet who restated the philosophical ideas of Epicurus in
Latin hexameters. But the pessimism of the Greeks was too
fundamental for this view to be maintained, and Lucretius
himself expresses his skepticism of the value of civilization.
When Prometheus stole the fire from heaven and Icarus
adopted wings, they paid for their daring the penalty that
they owed to the gods whom they had challenged. The
Greeks were resigned, in fact, to a fixed order of the uni-
verse, and any idea of progress toward perfection would have
been a violation of that fixed order.

The organization of Europe under the Romans did noth-
ing to make men feel that a definite progress in the conditions
of mankind was possible. Those conditions, indeed, were
bad, at best. The economic foundation of the Roman Em-
pire was unsound. Its government was a totalitarian tyranny.
It is not without significance that the historical doctrines
of German National Socialism are akin to those of Marcus
Aurelius.

With the rise of Christianity, an entirely ne^v idea of
human history was introduced— the idea that life on earth
was on the verge of ceasing. For St. Augustine, as for any
believer of that time, the course of history would be satis-
factorily complete if the world came to an end in his own
lifetime. The Christian church had started as a group of
disciples waiting for the return of their leader, and for the
early church the orthodox theory was that the Second Com-
ing might be expected at any time. Moreover, the basis of
the Christian religion was the idea of the individual's fall
from grace and his redemption from sin by the sacrifice of
the god. History, then, was the history of a degenerate world,
some of which might finally be redeemed and, with that re-
demption, obliterated by absorption into the godhead.

6 THE PATH OF SCIENCE

The great change in these ideas came at the beginning of
the seventeenth century and was expressed most clearly in
the work of Francis Bacon. The part that Bacon played in
the growth of science will be discussed later. We are at
present concerned only with the effect that he produced upon
the thought of his time. Bacon was not a scientist or an
experimenter; he was a theorist and planner. He laid down
an ambitious program for a great renovation of knowledge
based upon his view that the secrets of nature could be
determined by experiment and that the value of scientific
knowledge lay in its utility. Thus the proper end of human
knowledo^e was the amelioration of the conditions of human
life. For this purpose Bacon saw that organized scientific
research— the study of the learning of the past and the de-
velopment of new learning by direct observation and ex-
periment—must result in the most important advances.
He pointed out that three great inventions unknown to
the ancients— printing, gunpowder, and the compass— "have
changed the appearance and state of the whole world; first
in literature, then in warfare, and lastly in navigation; and
innumerable changes have been thence derived, so that no
empire, sect, or star appears to have exercised a gieater power
or influence on human affairs than these mechanical dis-
coveries." *

With Bacon and with the increase in scientific discovery
that followed, the idea of progress became the dominant
theory of history. This was supported by the philosophy of
Rene Descartes, who insisted on the invariability of the laws
of nature and the supremacy of reason, which, carried to a
logical conclusion, excluded the doctrine of providence, the
basic belief of the Christian philosophers. The development
of the idea of progress through the seventeenth and eighteenth
centuries is of interest primarily to a student of philosophy.f
It was embodied in Immanuel Kant's philosophy and in the

* Francis Bacon, Novum Organum, 129.

■j- For an excellent discussion of the subject, see J, B. Bury, The Idea
of Progress, New York, The Macmillan Co., 1932.

THE INTERPRETATION OF HISTORY 7

positivism of Auguste Comte. It was perhaps a result of
Comte's work that the idea of progress became so completely
accepted by the people of the nineteenth century, and it is,
of course, the basis of Herbert Spencer's philosophy, em-
bodied in his First Principles^ published in 1862. Belief in
progress was greatly reinforced by the rapid development of
science and technology and by the manifest improvement in
the conditions of life.

Nevertheless, the cyclic theory of history, held by the
Greeks, has not been abandoned in modern times. The
theories of Plato and Polybius, that the history of states
must repeat itself, were worked out in detail by Vico in the
eighteenth century and used as a fundamental theory of his-
tory by Brooks Adams in his Law of Civilization and Decay.
Adams bases his interpretation on psychology, seeing in fear
and greed the two great motives for human action. These
two motives, he thought, alternate through the course of his-
tory, so that we have first a stage in which fear predominates
and civilization is organized on a military and imaginative
basis. In this stage, there is an accumulation of wealth, and
society is centralized. This centralized society then transfers
its central motive from fear and the military state to greed
and the economic state. The productive power of this state
collapses as a result of the greed of the individuals in a capi-
talistic society, and the military phase of expansion recurs.

Brooks Adams takes a deeply pessimistic view of human
history and, indeed, of human nature. According to him,
men have been almost invariably scoundrels inspired by fear
or by greed. Such a view of the motives that have moved
men in the past and of the characters of those who could be
moved almost entirely by such motives is sufficient to refute
the entire argument. In the absence of any specific informa-
tion to the contrary, the best assumption as to the nature of
men in the past is that it was the same as that of men in the
present. Nevertheless, it is true that nations pass through
successive stages of integration and disintegration. States
have been built up by conquest and assimilation, and then,

8 THE PATH OF SCIENCE

with the gi'owth of wealth and leisure, they have been the
prey of external aggressors. The aggressors have flourished
and have in turn relapsed into weakness and perished. Thus
the history of individual nations shows a cyclic rhythm.

Another cyclic theory of history has been developed by
Oswald Spengier in his famous book, The Decline of the
West. Spengier presents history as a succession of cultures,
each of which follows a definite coinse of development
through a sequence of phases. He holds that each culture
has its own peculiarities but that the course of development
through the phases is the same for all. Thus each culture
has its beginning, its development based essentially on rural
life. It then blossoms into full strength, with the urban
population taking control of the thought of the nation until,
finally, there comes a decay, particularly of religion and of
inward life, and a collapse of the culture as a whole. A
necessary part of Spengler's argument is that the same phases
are distinguishable in all cultures. He treats the Renaissance
as a revolt against the Gothic, the exhaustion of the early
phase of modern culture. Similar revolts occurred in Egypt
at the close of the Old Kingdom Avith the development of the
feudal system and in Greece at the close of the archaic period,
though, surely, the corresponding period in Greek culture
should be that at which the Hellenistic displaced the Hel-
lenic. Spengier carries these analogies to the individuals of
the phases. He considers Napoleon a parallel to Alexander.

An excellent analysis of Spengler's -^v ork has been made by
Colling^vood, who points out that Spengier carries this theory
to an extreme; every phase and every detail reappears in
each cycle.* Since obviously this is not true of history, the
cycles cannot be identical. Rather, they must be homologous
—in each cycle the events and personalities must correspond
structurally to events and personalities of the past. The task
of the historian is, therefore, parallel to that of the compara-
tive anatomist; he inust depict the correspondence of the

* R. G. Collingwood, "Oswald Spengier and the Theory of Historical
Cycles," Antiquity, I, 311 (1927).

THE INTERPRETATION OF HISTORY 9

events in two cycles ^vhile realizing their differentiation aris-
ing from the differences between the cycles. It is useless
merely to mention likenesses in history— to compare Alex-
ander with Caesar or Buddha with Christ. Nevertheless,
these likenesses must be recognized at the same time that
their differences are realized.

Collingvvood compares Spengler's cyclic theory with the
doctrines of Plato, Polybius, and Vico, and points out that
Spengler apparently did not know of the work of Sir Flinders
Petrie, ^\hich is discussed later. Probably the popularity of
Spengler's book arises from his claim to foretell the future.
According to Spengler, the present era is that of the collapse
of a civilization— a plutocracy disguised by demagogism and
no^v^ called "democracy"— corresponding to that of the second
century B.C. in Rome, when the Roman republic was col-
lapsing and the civilization of the ancient world as a ^vhole
was moving to^vard the tyranny of the Roman Empire and
the darkness that followed it. This idea of Spengler's seems
to lie at the root of much of the totalitarian philosophy. But
Spengler's claim to foretell the future is, as CoUingwood
points out, baseless. Even if the general pattern is repeated
in cycles, there is no evidence that those cycles resemble
each other closely enough or are sufficiently uniform in length
or intensity to enable us to predict anything except that there
will continue to be cycles.

The tremendous events of the last ten years, during w^hich
some of the most active and capable nations have challenged
the ideals on which western civilization was founded and
plunged into world-wide war to enforce their challenge, have
produced doubts in the minds of many thinkers as to the
validity of the idea of progress. Some years ago, Mr. Philip
Cabot wrote to a friend:

The period covered by my father's life, and most of my
own, was one in which wise men in Western Europe and
in America looked forward to the future with confidence
and hope. Of course, their world was menaced by the
dangers which have always distressed mankind— war, pesti-

10 THE PATH OF SCIENCE

lence and famine. But to these the race has become inured,
and the hope of this period appeared to be based on reason-
able foresight. Their troubles were mostly in the present;
their future seemed remarkably secure.

Now the outlook has changed. We still have our pres-
ent troubles, and to them has been added grave anxiety
about the future, an anxiety which is most marked among
thoughtful men. For there is reason to doubt whether we
shall be able to hand on to our children unimpaired the
great social structure which we received from our fore-
fathers.

At the time that Cabot wrote this, he was not thinking
directly of the great threat that was developing in Central
Europe and that in 1939 broke on the world in a tempest of
fire and steel. Instead, as he said in his commencement ad-
dress to Juniata College on June 1, 1936,* he felt that the
danglers that threaten us are internal and arise from the loss
of the fundamental agreements upon which the life of our
society is based. Social disintegration appeared to him to be
foreshadowed in the weakening of family life, the breakdown
of social conventions, and especially the decay of religion.
These changes arise from the fluidity and increase of wealth
and from the great mobility of the population, so that scarcely
any families live in the old homestead and few live many
years in the same place. People no longer feel that they
belong to a definite group, and without such a feeling so-
cieties are unlikely to persist.

It is by no means the first time in the history of the world
that rapid changes have occurred, both in relation to the
material control that man has over his environment and also
in relation to the economic and social structure of society.
Frequently these changes, accompanied by great mass move-
ments of peoples, have resulted in the destruction of cities
and the erection of new empires on the ashes of the old.
Between the fourteenth and the twelfth centuries b.c, such
a ereat chano^e occurred and it resulted in the destruction of
the oldest stable empires of which we have any record. The

* Philip Cabot, Addresses 1935-1941, Cambridge, Mass., 1942.

THE INTERPRETATION OF HISTORY 11

origin of that change we do not know. It was quite possibly
the culmination of climatic changes occurring in the great
plains of Eastern Europe and Western Asia. In the course
of it, Crete lost her control of the northern Mediterranean
and finally vanished from the list of the empires. The
Achaean Greek civilization that Crete had founded disap-
peared in its turn. The Hittite Empire, attacked in the
north, pressed through to the south, came into conflict with
the new power of Assyria, and was destroyed. Assyria con-
quered Babylonia and expanded its new empire, which was
eventually to overrun Egypt itself.

In the fifth century a.d., a similar rapid change in the
organization of world power and, consequently, in the eco-
nomic and social life of the civilized world took place. The
Gothic invasion of Italy after the division of the empire
between Rome and Constantinople terminated the domina-
tion of the western world by Rome.

In the fifteenth century, again, centralized monarchies took
the place of the feudal system, and that system that had ruled
the world for a thousand years deliquesced and changed be-
fore the eyes of men. And then Northern Europe largely
abandoned its traditional religion and established a new
church, carrying with it altogether new and different social
relations.

But the progress made in the material aspects of civiliza-
tion in the three hundred years that have elapsed since the
birth of Newton is as great as that made from the neolithic
period to the time of his birth. A man of Newton's day who
left London or Paris and by some Time Machine found
himself in ancient Rome, Athens, or Thebes would have
missed few of the conveniences and amenities of life to which
he had been accustoined. In some respects, indeed, he might
have found himself better off. The water supply and the
drainage system of ancient Rome were better than those of
Elizabethan London. The buildings of Thebes or Athens or
Rome were greatly superior to those of London or Paris in
the seventeenth century. The mind of man, the intellectual

12 THE PATH OF SCIENCE

atmosphere, was much the same. The absence of Christian-
ity and especially the extent of slavery would make the social
world rather different to our voyager, but for his bodily com-
fort he would find that he had lost little in returning to the
ancient world. But if the man of today should go back to
the world in which Newton was born, he might not find him-
self mentally in a remote world, but physically he would be
astonished and shocked. The clothing would strike him as
primitive; the houses, as crude and uncomfortable. Few
would care to live in Wolsey's palace at Hampton Court, and
Wolsey was a man who loved luxury. The sights and the
smells, the dirt and the vermin of the cities of that time
would be most offensive to him. The inconveniences of
travel, the unpaved streets, the absence of sanitation, and
the appalling disease would make him realize how great a
change has come over the ^\ orld. He would soon, of course,
become accustomed to the conditions, just as men today be-
come accustomed to primitive conditions when they en-
counter them. But ho^v inconvenient to be without matches,
without any satisfactory water system, and, for those ^vho are
inveterate readers, to have a very limited supply of books
and no satisfactory system of artificial light!

These comforts and conveniences, ^vhich are today nor-
mally taken for granted, have been achieved by the work of
the technologists and scientists of the last three hundred
years. Moreover, even the industrial revolution of the nine-
teenth century probably produced less change in the life of
man than has occurred during the first third of the twentieth
century. Many writers on sociology have commented on the
recent changes in social conditions and in human relations
as being psychological and sociological phenomena; and
among these are a number of the most distinguished philos-
ophers and thinkers of the present time. A. N. Whitehead,
discussing the present as a turning point in the sociological
conceptions of western civilization, concludes that through-
out the w^hole of the western world "something has come
to an end."

THE INTERPRETATION OF HISTORY 13

In Russia there has been a revolution, because some-
thing has come to an end. In Asia Minor the Turks are
recreating novel forms of social life, because something
has come to an end. In the larger nations of Western
Europe, Italy, Spain, France, Germany, England, there is a
turmoil (
an end.*

turmoil of reconstruction, because something has come to

But men do not look back ^\ hen they come to the parting
of the ways; they look forward. And the cause of these "revo-
lutions," these "ferments," these "turmoils" is applied science
and the promise that men can see in it. C. A. Beard in his
introduction to Bury's Idea of Progress {loc. cit., page 6)
points out that the basis of modern civilization is technology,
which indicates the methods by which the conquest of nature
can be effected. Technology involves not only the existing
machines and processes but still more a philosophy and a
method linked, as it were, to the methods and spirit of
science. Moreover, technology is world-wide and universal,
available to all nations and affecting all classes. Thus tech-
nology is at once the source and the justification for the idea
of progiess. Mankind has not merely advanced from primi-
tive culture; it has developed a working method for a con-
tinuation of that advance. There is no reason to believe that
the present civilization ^vill run its cycle and relapse into
barbarism; there are no limits to the possibilities of scien-
tific discovery and its application to the wants of man. The
solution of a scientific problem does not close a chapter; it
opens new problems. Moreover, advances in one field of
science make possible advances in another. The solution
of a physical problem throws light upon chemistry and that,
in its turn, on physiology or on medicine. Until man has no
more curiosity and no more ^vants, his quest for kno^vledge
will persist and the application of that knowledge will con-
tinue.

W^hat distinguishes the present change in sociological con-

* A. N. Whitehead, "The Study of the Past— Its Uses and Its
Dangers," Harvard Business Review, XI, No. 4, 436 (1933).

14 THE PATH OF SCIENCE

ditions from those that have gone before is the rate at which
the change is occurring. Earlier changes in the social struc-
ture, such as those that occurred at the end of the Roman
Empire, were extremely slow in comparison with the changes
that we have seen in our own lifetimes. At the present time,
the rate of change is greater than any in the previous ex-
perience of man, and it appears to be still accelerating. The
rate is, indeed, so great that it is often said that the world is
passing through a social revolution. On this point, one may
agree with Cabot that the word "revolution" is too strong.
Revolution suggests an explosion, and such an explosion may
occur; indeed, the German and Japanese attacks might be
considered explosions. But apart from these aggressive ac-
tions, which are not necessarily due to the social changes,
what is occurring is not social revolution but social evolution
at a very rapid pace.

An important contribution to the study of the situation
was made by the late Lord Stamp in his book The Science of
Social Adjustment, the first chapter of which is entitled "The
Impact of Science upon Society." * Stainp points out that
the specific phenomenon that we have to investigate is what
occurs at the point of impact, where the new discoveries and
inventions affect our social life, and here the rate of change
is of primary importance. In his book he discusses as an
economist such matters as the obsolescence of machinery,
the displacement of labor, the changes in industry and in
the population.

Many of the most important changes produced by science
are not generally recognized as such. Everybody realizes
that the introduction of the railroad train, the automobile,
and the airplane have changed social conditions; but by far
the most important factors in the changes that are occurring
in society arise from the prolongation of human life. Not
a generation ago, life expectation at birth was forty years;
today it is sixty. This produces a change in the distribution

* Sir Josiah Stamp, The Science of Social Adjustment, London, Mac-
millan and Co., 1937.

THE INTERPRETATION OF HISTORY 15

of age among the population— a decrease in the percentage of
children and an increase in the numbers of the older— that
must have a profound effect upon the organization of so-
ciety. The problems of India that arise from its political
situation, grave as those are, are by no means the most im-
portant for the future of the country. As A. V. Hill has
pointed out in his report on his visit to India on behalf of
the Royal Society, the great problem in India is the ex-
traordinarily rapid increase in the population owing to the
improvement in medical and sanitary conditions, far behind
those of the western world as they still are. The society of
India, with its many complications of custom and religion,
was adapted to a large birth rate and an appalling death rate.
Even a sliofht reduction in the death rate has been sufficient
to upset the balance.

The growth of science, which made it possible to conceive
the idea of progress and which is the source of many im-
provements in the conditions of human life, has become so
rapid that the changes that it produces threaten the very
foundations of society. Today we have to face the necessity
for a complete re-orientation of our attitude tow^ard social
conditions. We can no longer expect the organization of
society to remain stable. We must expect it to be changing
continually, and we must plan our political and economic
control not to perpetuate any existing state of affairs but to
meet the changes that will come in such a way that they will
give us the maximum benefit and the minimum distress.

In this book we shall discuss the structure of society from
the historical point of view, especially its relation to the
development of scientific knowledge and the methods that
have been and can be used for the production of scientific
knowledge.

While the relation between the progress of scientific dis-
covery and the structure of society is of the utmost interest
and importance to those who desire to understand it or, still
more, to control the changes that are occurring, there is a
cleavage betw^een those who follow the discipline of history

16 THE PATH OF SCIENCE

and of the humanities and those who are eagerly pursuing
the quest for scientific knowledge. Humanistic learning is
the learning of the ancients; it is a study of the accumulated
thought of mankind so far as it has been transmitted to us.
Scientific knowledge, on the other hand, is a development
arising from the observation of facts and their classification
into patterns. The separation of these two types of learning
has always been unfortunate; at present it is serious, and it
may, indeed, be disastrous. As Sarton says, "The most omi-
nous conflict of our time is the difference of opinion, of out-
look, between men of letters, historians, philosophers, the
so-called humanists, on the one side, and scientists on the
other." * The administrators and organizers of society have
been trained chiefly in the humanities and are largely igno-
rant not only of the facts of science but of the scientific
method. The scientists, on the other hand, are absorbed in
their own problems and too often have little time to spare
for the study of history, even the history of science. It is
essential that a reconciliation bet^veen the two branches of
learning should be effected and that the present dichotomy
of our cultural and educational systems should be resolved.
The humanists must understand what the scientists have
done in the past, are doing now, and may do in the future;
while the scientists must see their work in the light of history
and in relation to the effects that its application to social
conditions will produce.

Now let us turn to the pageant of history and endeavor to
see some design in its structure that may reconcile in one
general pattern the different conceptions of history that we
have discussed.

* George Sarton, The History of Science and the New Huinanisyn,
p. 54, Cambridge, Harvard University Press, 1937. All quotations from
this author are rej^rinted by permission of the publishers.

Chapter II
THE HELIX OF HISTORY

History involves the study of human progress. The record
of that progress is to be found on the earth itself— a frag-
mentary record of giaves and building stones, of broken tools
and potsherds— which can be interpreted to give the story of
the ascent of man. But the greater part of history as it is
written by historians is the history of written documents.
Indeed, many historians maintain that only w^ritten docu-
ments can supply trustworthy history and that evidence from
other sources is not really history but should be dealt wdth as
a separate science, the science of archaeology. The result is
that the historian often fails to give the reader a perspective
of human history as a whole because he finds it necessary to
devote practically all his space to discussions of the ^vTitten
evidence and the rewording of the ^vritings of his prede-
cessors. As Gordon Childe points out in his essay on the
writing of history, this is particularly unfortunate if we are
endeavoring to follow the development of science and tech-
nology through the ages.* Even those scientific discoveries
which are necessarily committed to writing— mathematical
calculations and formulae, for instance— have generally been
neglected by students who, as Childe says, ''were by training
inclined to prefer historical and mythological literature and
w^ere, in any case, hardly competent to appreciate the true
inwardness of the problems the ancient scribes were trying
to overcome."

Most of our information on the technology of the ancients
is necessarily derived from the material objects discovered by

* Gordon Childe, "The History of Civilization," Antiquity, XV, I
(1941).

18 THE PATH OF SCIENCE

excavation, and only too often that information is fragmen-
tary and obviously insufficient. The known instrumental
equipment of the Egyptians seems scarcely sufficient for the
great engineering works which they undertook. Was Galileo
or his immediate predecessor really the first to combine two
lenses to make a telescope? While we should certainly not
accept the existence of such instruments in much earlier
times without adequate evidence, we should as certainly not
regard their existence as impossible.

Again, in the absence of definite records, historians tend
to overrate the isolation of countries and cultures in early
times. It is true that in the early part of a cycle of culture, as
in Greece in the eighth century B.C., contact with other coun-
tries was largely lost. Six hundred years earlier, however,
communications between Egypt, Babylonia, and Asia Minor
were so good that there was something approximating a postal
service, and because of its convenience correspondents in all
these countries used a common language— Babylonian written
in the cuneiform script. The visit of a Pharaoh of the Old
Kingdom to Crete, imagined by Miss Grant in her novel,
while unlikely, is certainly not impossible.*

To get a true view of the pattern of history, it is necessary
to broaden our outlook as much as possible and to cover not
only the whole of recorded history but also the prehistory of
the archaeologist. As Childe says: 'Tor the prehistorian, the
colonization of the Mediterranean basin by the Phoenicians
and the Greeks is but the continuation of the Minoans' pio-
neering efforts. To the historian, the empires of Assyria,
Babylon, Persia, and Macedon must appear fulfillments of
the ambitions of Sargon of Agade, Ur-Nammu, and Ham-
murabi."

When we attempt to contemplate history broadly, to com-
pare the events of one period with those of another, there is
a strong tendency to distortion arising from the point of view.
It is almost as if the difficulty were one of perspective. Sup-

* Joan Grant, Winged Pharaoh, New York, Harper and Brothers,
1938.

THE HELIX OF HISTORY 19

pose, for instance, the scale of the years is marked along a
wall. If you stand in front of the middle of the scale, some
distance away, the equal periods of time will be represented
by equal distances and by equal angular deviations of view.
But if, instead, you stand at the end of the scale and look
down it lengthwise, the portions of the scale that are near you
will seem very much longer than those that are distant; and
near events will seem much more important than the more
remote ones. The time scale of human progress is certainly
not linear. Technical progress grows more rapid as time
goes on, and perhaps the best chronological scale for the his-
tory of science and technology would be one in which the
divisions of the scale were proportional to the logarithms of
their distance from the present time.

Another example of this distortion is that it is impossible
for us to understand the effect on human history of the events
that are occurring around us.* Our judgment of the im-
portance of the events of the time is very likely to be different
from the judgment of history. There comes to mind Anatole
France's story of the procurator of Judea, who was visited
in retirement by a friend who had known him in Syria.
Their conversation strayed on to the events that had oc-
curred when Pontius Pilate had been in office in Jerusalem,
and his friend asked him if he remembered a certain Jesus
whom he had delivered to crucifixion. Pilate's answer will
forever remain the most perfect example of the ironical
climax: *'Jesus?" he murmured, "Jesus of Nazareth? I can't
call him to mind."

History is full of incidents which were ignored by contem-
poraries but which proved to be of the greatest importance.
In 1453, Constantinople was taken by the Turks. The blow
was felt throughout Christendom; a European congress was
called at Regensburg to promote a crusade, but nobody would
come. The organization of Europe had broken down, ex-
hausted with war and quarrels. A contemporary writer said:

* Cf. H. B. Phillips, "On the Nature of Progress," American Scientist;
33, 253 (1945).

20 THE PATH OF SCIENCE

"Where is the mortal man who can bring England into ac-
cord with France? Let a great host set forth, and its internal
enmities will destroy its organization. Behold, a true picture
of Christendom." * Few would have been found who real-
ized that the final fall of the Byzantine Empire was far less
important than the work of Johannes Gutenberg, who for
the first time was printing books from movable type.

At the time when Isaac Newton was preparing the Principia
for publication, in 1686 and 1687, the British people were
engaged in a bitter struggle with the king, arising from the
fact that the king was a Catholic, while the people as a whole
had become Protestants and after years of struggle had a very
great fear and hatred of the Roman Catholic church. The
feeling was so bitter that the struggle ended in the expulsion
of the king, whose place on the throne was taken by his Dutch
son-in-law, William, and his daughter, Mary. It may easily
be imagined that in a political crisis of this magnitude few
people saw that the work of a professor at Cambridge was
of far greater significance for the future of England and of
the world. Again in 1831, England ^vas seething with dis-
content. Even the old Duke of Wellington, the victor of
Waterloo, was threatened by the mob. The Reform Bill
had been defeated in the House of Commons and a dissolu-
tion of Parliament was necessary. In these circumstances,
probably no one recognized that the work of Michael Fara-
day, who in that year discovered the principles of electro-
magnetic induction, was to change the face of the earth.

There is no absolute standard for the judgment of history.
One individual will be interested in history as a record of
administration; another, as a record of the art of human wel-
fare; another will view history in relation to economics; a
medical man has written two very interesting books on the
medical aspects of the history of well-known individuals;
in this study we are considering the progress of civilization
through the ages.

* Boulting, "Aeneas Sylvius," quoted by J. W. Thompson, The Middle
Ages, p. 205, New York. Alfred A. Knopf, Inc., 1931.

THE HELIX OF HISTORY 21

Sarton says: "If we wish to explain the progress of man-
kind, then ^ve must focus our attention on the development
of science and its applications." This view is emphasized
by Sarton in his definitions of science and the theorem and
corollary he derived from it.* They are:

Definition: Science is systematized positive knowledge,
or what has been taken as such at different ages and in
different places.

Theorem: The acquisition and systematization of posi-
tive knowledge are the only human activities w^hich are
truly cumulative and progressive.

Corollary: The history of science is the only history
which can illustrate the progress of mankind. In fact,
progiess has no definite and unquestionable meaning in
other fields than the field of science.

Sarton points out that we should not be dazzled by the
shibboleth of progress, for there are other features of human
life which are at least as precious as scientific activities though
they are unprogressive; and he instances charity and the love
of beauty. Nevertheless, the scientific activity of man is the
only one which is obviously and undoubtedly cumulative
and progressive.f As we have seen, the very idea of progress
is modern, an idea that derived from the scientific revolution
of the seventeenth century and the industrial revolution that
followed it.

The justification for selecting scientific knowledge as essen-
tially different from the artistic attainments or the philo-
sophical attainments of man is that scientific knowledge builds
on itself. An artist is essentially born. It is true that he
acquires a certain amount of technical skill when trained by
a master and is influenced by his predecessors, but funda-
mentally the level of his art is his own, and for that reason
the best art of the early periods compares well with art of
the later periods.

* George Sarton, The Study of the History of Science, p. 5, Cambridge,
Harvard University Press, 1936.

f George Sarton, History of Science and the New Humanism, p. 10,
Cambridge, Harvard University Press, 1937.

22 THE PATH OF SCIENCE

What is true of sculpture and architecture is true also
of literature. Literature takes different forms in different
periods. W^e may be inclined to value, for instance, the lyric
poetry of the recent era. But would we place it above the
epic poetry of the classical age or the religious poems of the
great period of high civilization which preceded the classical
age— from which we have such writing as the Book of Job or
Akhnaton's Hymn to the Sun? The science of the Renais-
sance, however, started where classical science ended, and
classical science was largely based on Egyptian and Baby-
lonian science. Through the ages, while the other activities
of man showed no definite progression but merely a growth
for a time and then a decline, the level of scientific knowl-
edge steadily increased. As Sarton says: *

When one reads the history of science one has the ex-
hilarating feeling of climbing a big mountain. The history
of art gives one an altogether different iinpression. It is
not at all like the ascension of a mountain, always upward
whichever the direction of one's path; it is rather like a
leisurely journey across a hilly country. One cliinbs up to
the top of this hill or that, then down into another valley,
perhaps a deeper one than any other, then up the next hill,
and so forth and so on. An erratic succession of climaxes
and anticlimaxes the amplitude of which cannot be pre-
dicted.

Let us consider, then, the progress of mankind as illus-
trated by the history of science or, as I should prefer to say,
the history of science and technology, the record of natural
knowledge and of invention.

We may divide the history of mankind into gieat periods,
each of which is conditioned by a major invention; and it
is possible to carry out this division in many ways, accord-
ins: to the controllingr inventions that we select. The follow-
ins: classification seems to form a convenient framework for
our discussion:

* Ibid., p. 11.

THE HELIX OF HISTORY 23

1. The invention of tools and weapons.

2. The discovery of agriculture.

3. The invention of writing.

4. The invention of printing.

By the first of these inventions man evolved from the
animal. Agriculture introduced community life, and from
it evolved a structure of society. With ^vriting came the pro-
duction of records and the transmission, imperfect at first,
of knowledge. With the invention of printing, the spreading
of knowledge from the writing of one man to become the
common heritage of mankind was so enormously facilitated
that printing produced a revolutionary change in the rate of
progress.

Our record of man opens W'ith the fragments of tools and
pots, the tools long before the pots. The tools were made
from wood, bone, or flint. The wood has vanished, and few
of the early bone tools remain, but the flint tools form a gieat
record— almost the only record we have for the first 40,000
years of the 50,000 during which man has made and used
tools. Those first 40,000 years are covered by the paleolithic
period; the neolithic period starts at about 10,000 b.c; and
the historical period some time after 5000 b.c* This earliest
record we know— that of the flint w^eapons and tools made by
prehistoric and neolithic man— can be deciphered by the
changes and improvements in the tools and by the improve-
ment in the technique by which the tools w^ere made.

Flint is found wherever there are chalk deposits, as there
are in many parts of Western Europe. The great nodules
of flint are found in cavities in the chalk rock and can easily
be obtained by anybody who digs a hole in the ground.
There are some places w4iere there are layers of flint that
form flint mines, and around these places the ancient men
w^orked so many flints that the whole ground is covered with
masses of flakes. If a lump of flint is struck with a sharp

For a modification of this chronology and a discussion of prehistoric
chronology, see G. E. Daniel, The Three Ages, London, Cambridge
University Press, 1943.

24 THE PATH OF SCIENCE

blow concentrated at a point, it breaks in such a way that a
sort of cap can be Hfted off, exposing underneath a double
cone. If the blow is dealt on the margin of the block, a flake
comes off showing a swelling near the point of impact. This
method of working flints is known as "knapping." Because
of the durability of flint and the very long period during
which flint tools were made, enormous numbers have been
found both of the primitive hand axes and scrapers and of
the later, more specialized, tools.

In the paleolithic period, improvement in the flint tools
was very slow indeed. After a time, however, the craftsmen
learned to make finer and more delicate tools— pointed awls
for making holes in skins, by which the skins could be
fastened together with sinews— and weapons, spearpoints and,
later, arrow points. Then the art of knapping improved as
a result of the discovery that small flakes could be detached
accurately by pressure, so that the coarse serrations could be
subdivided and a much finer edge obtained, and then the
flints were polished and a smooth edge obtained by grinding.
At this time, other arts developed, and the whole cultural
period is distinguished from the paleolithic period by call-
ing it "neolithic."

Our knowledge of the history of that vast period of man's
activity depends upon the study of the progress of flint work.
It is quite probable that different stages in the art of work-
ing flint did not occur contemporaneously in different coun-
tries, so that in one part of the world man may have been
making paleolithic instruments, while in another part the
flint craftsmen had learned the neolithic art. Generally,
however, the occurrence of closely similar flint implements
in different places is held to indicate that the cultures were
contemporaneous. Flinders Petrie, for instance, considers
that the identity of flints from the Fayum of Egypt with
Solutrean flints from Western Europe indicates that the be-
ginning of his sequence dating was contemporaneous with
the Solutrean paleolithic period.

THE HELIX OF HISTORY 25

At some period between 10,000 and 5000 B.C., we find that
the people of the new stone age were appearing in Egypt
and Mesopotamia with their improved tools and also ^vith
other inventions— pottery and agriculture. Besides tools and
weapons, primitive man needed cooking utensils and still
more, perhaps, he needed jars in which he could carry and
keep water. Baskets were made very early. Stone jars also
were made, but they required much labor when made by
primitive tools. It was not a great step, though it was a very
important invention, to think of daubing the baskets with
mud and making them more or less w^aterproof. Probably
the discovery that the mud became much more waterproof
if it were baked in the fire was made accidentally. There
were plenty of open hearths in which a mud-daubed basket
might be left. At any rate, the earliest pots seem to have
had the mud-smeared basket as their ancestor. Later pots
could be made without the basketwork by baking the mud
itself, molded to shape, but those earliest pots still bear the
marks of their origin in the tracings of basketlike lines with
w^hich they are decorated.

And at that point, art entered the everyday world. The
pots could be decorated with mud of different colors and
with designs of intricate fancy. These patterns and working
methods were so stable that by means of them the cultures of
the neolithic and early bronze ages can be classified. We see
the steady improvement in the skill and fancy with which
the pots were formed, so that instead of depending upon the
classification of the flint tools, we can introduce approximate
datings for given periods from the potsherds with which
every ancient city is necessarily covered, pots being what
they are and children what they have always been.

A good example of the use of pottery in constructing a
time scale for material revealed by excavation is given by
Petrie in his dating of the remains of prehistoric Egypt. In
this work, he selected a thousand graves with at least five
forms of pottery in each. Then a card slip was used for each
grave with the content specified, and every occurrence of a

26 THE PATH OF SCIENCE

type of pottery was examined and compared with the other
examples. This process of comparison resuked in bringing
the thousand graves into a connected order in time, each
grave as a general rule containing some of the pottery of the
graves near it in the order but not containing pots of those
that were more distant in the order. The whole series of
graves could be divided into fifty parts, and these were num-
bered arbitrarily from 30 to 80 in order to leave space for
later discoveries of graves that might not fit into the sequence
and that might have to be placed before or after those that
had been examined. In this way, a definite sequence dating
could be made for the graves and, therefore, for the pottery
and other material found in the graves, ending ^vith the
graves of the historical dynasties for which chronological
dates were kno^vn. The same method has been applied to
the dating of the different levels of excavation in Mesopo-
tamia and Syria. Indeed, our knowledge of prehistoric Meso-
potamia is almost entirely dependent on dating by means of
pottery.

At this stage in the history of civilization, when men had
the good tools of the neolithic age and pots hardened in the
fire, a new factor of fundamental importance appeared— the
second of the great inventions of mankind.

Agiiculture was probably discovered by the women, who
gathered the seeds of plants while their men hunted animals.
One day they must have realized that seeds could be sown
artificially and that, if they waited long enough, seeds pro-
duced a crop. With the coming of agriculture came real
civilization. Men ceased to be nomads. They settled in
villages; and those villages were naturally along the river
valleys, where there was mud, in which the seeds could be
planted, and water, necessary for plant growth.

There, in the villages or, rather, in the to^vns into which
the villages had grown, came the third great invention— writ-
ing. And with writing, the period of prehistory ends and
history commences. Man began to write five or six thousand
years ago. Those who study the river valleys of Mesopotamia

THE HELIX OF HISTORY 27

claim that writing had its origin there, but it certainly origi-
nated independently in Eg)'pt, and the Egyptologists are by
no means willing to concede the claims of their archaeological
rivals.

In oiu' study of history after the invention of writing, we
are less dependent on material relics and can use the records.
However, we are still interested in tracing the history
of civilization in terms of its arts and crafts, in the tools,
weapons, and ornaments that ancient man produced and left
behind him, although we have available generally from the
early periods only that small fraction of the production which
"^vas buried in the graves.

Having summarized the progress of man through the pre-
historic period until the invention of the written record, let
us endeavor to look at the history of civilization as a whole
and consider the nature of the phenomena it displays, in the
same way that we should consider any other group of natural
phenomena.

Any contemplation of the pattern of history gives at once
an impression of cyclic change— of the rise, flo^vering, and
fall of local civilizations of peoples and of empires. Many
empires have risen to power and fallen again in the last 5000
years. Some had a very brief triumph, like that of Attila
the Him or Alaric the Goth or, much more recently, of the
Swedish Empire, which for a short time ruled all northeast-
ern Europe. Others lasted much longer, the maximum dura-
tion being the 3000 years which the Eg) ptian system endured.

Indeed, when Tve contemplate Egyptian history we get the
impression of cyclic rise and fall within the life of that coun-
try, suggesting that this cyclic structure is not connected ^vith
the individual nation, race, or empire but with the period of
time, and that the long duration of the Egyptian system
enables us to discern within that duration several cycles.
Thus, from the prehistoric beginnings of Egypt, we find a
rapid advance in architecture and sculpture to the time of
the pyramid builders in the Fourth Dynasty, corresponding
approximately to 3000 b.c. The artistic level of the architec-

28 THE PATH OF SCIENCE

ture and sculpture o£ the Fourth Dynasty is considered by
many students to be equal to any that has been reached by
man, and the engineering work of the men who built the
pyramids shows an enormous development in technical skill
which was not exceeded for thousands of years. After the
great flowering of the Old Kingdom, as it is called, the level
of culture in Egypt slowly decayed. There was a period of
decadence, of bad and weak government, with the introduc-
tion of a feudal period, in which the land was governed, and
too often misgoverned, by local barons. It was the first re-
corded period of depression, and it was recognized as such by
the writers of that time. Then, about 2100 B.C., the Middle
Kingdom of Egypt rose in all its glory, producing not only a
great renaissance of art but also the building, as Herodotus
tells us, of the most prodigious palace ever erected by man-
that great building which Herodotus says was greater than
all the temples of Greece put together. Then again came
darkness, this time from the invasion of the Hyksos, who
seized the throne of Egypt. Again a king from the south
restored the power of the Egyptians and founded the great
Eighteenth Dynasty, which ended in a blaze of glory in
1350 B.C. Part of its treasure was buried in the grave of
Tutankhamen. Then the long degeneration of Egypt started
and continued until, with the invasions of the Assyrians and
of the Persians, Egypt fell, never to rise again. Thus, within
the recorded history of Egypt, there are three great cycles,
their maxima corresponding approximately to 3000 B.C.,
2000 B.C., and 1500 b.c; and following each of these maxima
there was a period of depression and decay.

In 1911, Sir Flinders Petrie wrote a little book that he
entitled The Revolutions of Civilization.* In this book he
uses his great knowledge of ancient history and, especially,
of the history of Egypt to develop a general interpretation of
history. He says:

* W. M. Flinders Petrie, The Revolutions of Civilization, Harper's,
1911, reprinted by Peter Smith, New York, 1941.

THE HELIX OF HISTORY 29

Can we extract a meaning from all the ceaseless turmoil
and striving, and success and failure, of these thousands of
years? Can we see any regular structure behind it all?
Can we learn any general principles that may formulate
the past, or be projected on the mists of the future? . . .
Hitherto the comparatively brief outlook of Western his-
tory has given us only the great age of classical civilization
before modern times. We have been in the position of a
child that remembers only a single summer before that
which he enjoys. To such an one the cold, dark, miserable
winter that has intervened seems a needless and inexplic-
able interruption of a happier order— of a summer which
should never cease. Only a few years ago a writer of repute
deplored the mysterious fall of the Roman Empire, which
in his view ought to have been always prosperous, and
never have fallen to the barbarians. He was the child who
could not understand the Tvinter. From what we now
know, it is evident, even on the most superficial view% that
civilization is an intermittent phenomenon.

Thus throughout history Petrie finds that cycles of civili-
zation have succeeded each other. In each cycle, the phases
are marked by similar characteristics which may be detected
by studying the products of the period. Each cycle has its
period of preparation, shown essentially in art as archaism;
then a period of maturity; and, finally, a period of decline
and decadence, to be follow^ed by the archaic period of the
next cycle. Petrie uses the simile of summer and winter for
the growth and fall of civilization and points out that this
analogy of the Great Year w^as familiar to the ancients. Petrie
uses as the most valuable index of the cyclic change the de-
velopment of sculpture, largely because it is more permanent
than other products of handicraft. He points out, however,
that sculpture "is only one, and not the most important, of
the many subjects that might be compared throughout the
various ages." [But] "it is available over so long a period in
so many countries." He adds to sculpture in his survey some
discussion of painting, music, mechanics, wealth, and even
political developments. It is remarkable that he lays little
stress on the development of technology.

30 THE PATH OF SCIENCE

In the last ten thousand years, covering the neoHthic and
historic periods, Petrie finds evidence of eight cycles, of which
the first two were found in prehistoric Egypt; then four,
covering the whole dynastic period of Egypt; and, last, the
classic and western European cycles. Each cycle starts with
an archaic period characterized particularly by the careful
working of detail without treating it as an integral part of
the whole. The rise from archaism to inaturity is almost
always rapid, and, after a period of inaturity, decline sets in,
characterized by a tendency to stiffness and conventionality
and a slow worsening and degradation of the style.

The most familiar cycle is, of course, that of the classical
period. We have the archaic Greek statues of the sixth cen-
tury B.C., followed by the great classical period of maturity
in the late fifth and fourth centuries, and then the transfor-
mation into the Hellenistic period, followed by the long
decay through Roinan times. To some extent, perhaps, this
cycle is complicated by a revival in the Roman period, accom-
panied by a copying of the Greek classical works by the
Roman sculptors.

If the classical period alone w-ere known to us, we should
dismiss the whole matter as being peculiar to the historical
events of that period; and this is generally done by historians
trained primarily in classical history. But the Egyptian evi-
dence for the existence of parallel cycles in sculpture is over-
whelming. The same type of cycle can be traced, for in-
stance, in Petrie's fourth period— that of the pyramid build-
ers—in the rise of the archaic sculpture, the freedom of the
sculpture and architecture of the Fourth Dynasty, the slow
decline through the Fifth and Sixth Dynasties, and the col-
lapse of the sculpture as the feudal system displaced the cen-
tralized government of the Old Kingdom. A new archaic
sculpture then came into evidence, rising to the maturity of
Petrie's fifth period in the Twelfth Dynasty, and then deteri-
orated, disappearing with the invasion of the Hyksos. The
sixth period cycle is that of tlie Ne^v Kingdom, ^vhere the
period of decline was very prolonged and ^\ as marked by the

THE HELIX OF HISTORY 31

great temple gioup built by the Ramesside rulers. To see
the difference between the artistic levels in maturity and in
the decline, one has only to compare Hatshepsut's temple at
Deir el Bahri with the great hall at Karnak built three hun-
dred years later.

To determine the duration of these periods, Petrie selects
the best-defined position in each cycle of the development of
art as the close of the archaic age in sculpture. This is best
defined, of course, because of the rapid improvement that is
generally noted at this stage; and, by means of it, there is
possible some appreciation of the period between the '^vaves
of art in successive cycles. Petrie believes that the average
period is about thirteen hundred years. It must be remem-
bered, however, that Petrie's early chronology is not accepted
by other scholars and that it is generally agreed that his dates
before 1600 b.c. need correction. If we use the chronology
generally accepted now, Petrie's chart gives five complete
periods in four thousand years, an average of eight hundred
years per cycle.*

By making judgments for subjects other than sculpture,
Petrie found that painting and literature tended to reach
their climax later than sculpture. He draws a chart in which
the different periods are shown as if they w^ere on the surface
of a cylinder, each period ending, of course, at the date at
which the next period began. In this chart, the points that
he has marked for sculpture, painting, literature, mechanics,
and wealth tend to diverge, each of them coming later as
the cycles progress. If this chart is redrawn with the early
chronology changed to accord with that accepted by J. H.
Breasted and other modern scholars— 3000 b.c. as the beorin-

ning of the Third Dynasty and 1800 B.C. as the end of the
T^velfth Dynasty— it becomes that sho^vn in Figure 1. Inter-
polating the new dates derived from those selected by Petrie
for the end of the archaic style in sculpture in each cycle, we
get the zigzag line shown. It is no longer possible to draw a

* But the modified chart shown in Figure 2, p. 34, gives a duration
of five hundred years per cycle.

THE PATH OF SCIENCE

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THE HELIX OF HISTORY 33

Straight line for sculpture, and the cycles clearly differ in
length, the early ones lasting only about five hundred years,
while the classical and medieval cycles last sixteen hundred
and fifty and fifteen hundred years, respectively.

The long cycles can very probably be corrected by con-
sideration of the historical facts. The classical cycle in
Greece did not start in 1200 B.C.; at any rate, it did not
start at any level corresponding to that existing in Egypt in
1200 B.C. If we put the beginning of the Greek classical
cycle at 800 B.C., and its end at 200 B.C., with the defeat of
Macedon by Rome, we get a cycle of normal length, which
can be followed by a Roman cycle of six hundred and fifty
years, starting with the destruction of Carthage and ending
with the fall of Rome. The course of art in the Roman cycle
is naturally affected by the persistence of Greek architecture
and statuary. Similarly, we can accept a discontinuity be-
t^veen the Roman and the medieval cycles and give the latter
its beginning in a.d. 1000 and its end in a.d. 1700, a length of
seven hundred years. If we accept these modifications of
Petrie's later cycles, we get the chart shown in Figure 2.

In an article in Antiquity, Collingwood discusses Petrie's
book and questions the value of his standards of artistic
achievement.* He points out that what Petrie calls decadent
another critic of art might consider beautiful. For example,
he holds that the Byzantine grave stele of Bellicia (Figure 3),
which Petrie classifies as occurring in the period of degrada-
tion between the classical and medieval periods, sho^vs vigor
of drawing and an "unearthly" beauty, and he considers that
it is unfair to compare its beauty ^vith that of a classical stele,
since it cannot be compared either as superior or inferior but
only different; that is, Collingwood claims that "beauty is
in the eye of the beholder," and that there are no fixed stand-
ards by which art at different times can be compared. He
says, in fact, that not only are there no dark ages except in
the sense in which every age is dark, and that there are ages

* R. G. Collingwood, "The Theory of Historical Cycles and Prog-
ress," Antiquity, II, 435 (1927).

THE PATH OF SCIENCE

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THE HELIX OF HISTORY

that individual historians dishke and misunderstand, but
there are also no decadences. Thus Colling^vood argues that
the cyclical view of history is a function of the limitation of
historical knowledge. History appears to consist of discon-
nected episodes, but, if we had more knowledge, we should

V/RCO

ins

Figure 3. The Stele of Bellicia. (From Petrie's The Revolutions of
Civilization, published by Peter Smith, New York, 1941.)

see that the episodes were connected; and he feels that Petrie
sees the structure of history as imposed by the historian view-
ing the scene and not inherent in the facts.

This view does not seem to accord ^vith the real situation.
Petrie's cycles are not based on the view of beauty adopted
by the onlooker; they are based largely on a technical matter,
the skill sho^vn in execution. A critic misfht endorse the
scribblings of a child or the primitive work of a Negro in the
forest as representing a degree of beauty which entitled them
to be considered excellent art, but there is no doubt that the

36 THE PATH OF SCIENCE

ability of the child or of the primitive Negro to reproduce
line and form is low. In the same way, the ability of artists
to dra^v or of sculptors to design and carve or of architects
to design and build has varied at different periods. Their
technical skill is not constant. The artist who drew the stele
of Bellicia may have drawn it in that form because he thought
it was beautiful, but it is absurd to imagine that that artist
was the equal in technical skill of the artist who carved the
Attic tombstones of the fifth and fourth centuries B.C. It is
very easy in a country like Eg)pt, where the standards of
judgments did not vary, to observe the variation in the tech-
nical ability of the painters, sculptors, and architects. The
carvings in the tombs show mastery over the subject, w^hich
increased as the cycle progressed, and then the style became
limited and stiff and conventional as decadence set in. This
is not a change in objective; the objects represented are the
same. It is a change in skill, in the mastery of the art. In
the decadent stage it is not uncommon to find that the artists
copied the designs of an earlier period because they recog-
nized that they had not the ability to originate designs of the
same quality as those which they were copying.

If, then, we accept Petrie's view of the existence of these
cultural cycles, let us follow his discussion of their origin.
After considering the effects of changes of climate, which
have often produced migrations of peoples, Petrie considers
that the rise of a new civilization is conditioned by the im-
migration of a different people; that is to say, it arises from
a mixture of two different stocks. The effective mixture can-
not take place all at once. When a new stock migrates into
a country, usually in a military invasion, there is an appre-
ciable barrier between the two races. But such barriers
always give way in time ^vhen the t^vo races are in contact,
and in seven or eight centuries the two races are completely
blended. Petrie concludes, therefore, that the cycle is started
by the invasion of a new stock, which introduces an archaic
period superimposed on the decadent style of the previous
cycle, and then, as the new stock blends with the old, artistic

THE HELIX OF HISTORY 37

and social development increases until the maximum is
reached. For most of the cycles discussed by Petrie, the
migration of a new stock appears to be a historical fact. The
dynastic people of Egypt, for instance, initiated Petrie's
fourth cycle, in which the peak \\a.s reached in the Fourth
Dynasty; people from the south, that of the Twelfth Dynasty;
the Hyksos invasion and the people of Thebes represent the
new blood for the New Kingdom cycle; the Doric invasion of
Greece initiated the classical cycle; and the influx of peoples
into the Roman Empire, the medieval cycle.

The origin of cycles is discussed in a very interesting article
by O. G. S. Crawford.* Starting ^vith Petrie's idea that the
development of a new phase of civilization depends upon the
crossing of two stocks having their ow^n cultures, Crawford
pursues a biological analogy, comparing Petrie's different
stocks with different varieties of animals and concluding with
a generalization that each phase of civilization has a life of
its own and may be regarded as if it were a species composed
of living creatures. Thus the life of each phase corresponds
to the life of a species as a whole; the units composing the
phases at any moment of history correspond to the individ-
uals composing the species; and a phase, therefore, is born
and passes through maturity to decline and extinction, just as
does an individual. The idea is not new. Crawford quotes
Sir Arthur Keith, ^vho says: "The resemblance between the
body physiological and the body politic is more than an
analogy; it is a reality." f

Just as a multicellular organism evolves from a single cell,
so the cultural community has evolved from free-roving in-
dividuals or small groups, this occurring, as has already been
pointed out, wdth the introduction of agriculture, -when the
nomads settled at one point and founded commimities. This
very operation can be observed occurring today, -^vhen the

* O. G. S. Crawford, "Historical Cycles," Antiquity, V, 5 (1931).
fSir Arthur Keith, Concerning Man's Origin, New York, G. P.
Putnam's Sons, 1928.

38 THE PATH OF SCIENCE

Bedouin of the desert have settled down into communities in
Trans-Jordan as cukivators of the soil. And it is interesting
to notice that the fact that the cultivators are of the same
tribes as the Bedouin does not preserve them from raiding
by the nomads. With the integration of the individual into
a cultural coinmunity, subdivision of function develops, just
as the single cells develop special functions in the multicel-
lular organisms. Crawford concludes that, looking at the
process as a whole, we can see that life evolves in a spiral. It
begins with a single cell. After many ages of development,
an organism is evolved that finally becomes a huinan being.
Human beings may be considered to be, in turn, the units of
organized nations that will evolve until they, in turn, become
the units or individuals of yet another society, this last being,
perhaps, the world state from which those races and social
systems that cannot be incorporated will eventually die out.
The idea of a society as an organism is to be found, of course,
in Spencer's synthetic philosophy; and the ideas that Craw-
ford discusses are dealt with formally in J. Needham's
Herbert Spencer Lecture.^

Leaving these wider specidations, we may ask: What is the
value of this cyclic theory to a student of history? When we
study a comparatively brief period of ancient history, it is im-
possible to understand its relation to any general scheme of
^vorld history. But if we accept the idea that civilization
moves in cycles, we can place any brief period in relation to
the events that preceded and followed it. As Petrie says, the
interpretation of the later Roman Empire is quite different
according to whether one assuines that the fall of Rome was
a unique phenomenon or whether one feels that the fall of
Rome was really one manifestation of the long decadence of
the classical cycle, to be follo^ved eventually by the archaic
period of the Middle Ages and the revival of the western
cycle. When discussing Roman law in Aspects of Social Be-

* J. Needham, "Integrative Levels," p. 233, Time, the Refreshing
River, London, George Allen and Unwin, 1943.

THE HELIX OF HISTORY 39

havior,* Frank finds it necessary to argue against the assump-
tion that Roman la^v had behind it nothing but a develop-
ment from a most primitive cuUure and reminds his readers
that the human race had existed many thousands of years be-
fore the reign of Romukis. He complains of some evolution-
ists, who write "as though Homer had just bid good-bye to a
grandfather A\ho hung by a tail from a Thracian oak tree." f
The cyclic theory is of valu.e, ho^vever, not only as a guide
to the thinking of the historian but also as a suggestion to the
modern philosopher. In an essay on modernism, Raymond
Dexter Havens expresses his uneasiness at the trend of art. J
He finds himself unhappy in a ^vorld in which Picasso is one
of the most esteemed of living artists, Schonberg and Hinde-
muth are representatives of music, and James Joyce and E. E.
Cuminings are leaders of literature, though he finally braces
hiinself to accept his fate and to see ^vhat he can make of God
in these "modern" methods of expression. But this type of
art is not really modern; there are many examples of it in
the past. If Picasso and many of his followers had painted in
the sixth century, we shoidd have classified the \vo\k very
simply as decadent. Epstein's sculpture would have been in
its natural home in Greece during the Byzantine period or,
for that matter, in Thebes in the ninth century B.C. Art is
not moving do^vn^vards permanently; it is merely moving
through the decadent stages of its cycle. And just as the
archaic and classical periods followed the decadent Egyptian
work of the ninth century B.C. and architecture in Europe
developed from that of the sixth century to its glorious maxi-
mum in the early Gothic of the twelfth, so there ^\'ill again
be artists who can depict natural objects and writers who can
explain what they mean.

* Tenney Frank, Aspects of Social Behavior, Cambridge, Harvard
University Press, 1932.

-j- This shows the danger of a classicist using scientific analogies.
Monkeys with prehensile tails are unknown in the Eastern Hemisphere!

X Raymond Dexter Havens, The Burden of Incertitude, Rochester,
University of Rochester, 1944.

40 THE PATH OF SCIENCE

In spite of the repetition of the rise and fall of art, of lit-
erature, and even of civilization as a whole, mankind has
made progress through recorded history. Cities and empires
have risen, and cities and empires have fallen. Artists, en-
gineers, and philosophers have lived and worked, died and
been forgotten, but none the less, some systematic secular
change has occurred. If the circle has come its full round,
the pattern of history is a spiral, not a ring, for the start of a
new cycle of civilization is never identical with that of the
last; and, on the average, each cycle starts from a point a
little above that of the preceding cycle, so that the successive
turns of the spiral are not coplanar, and the pattern may be
more accurately depicted as a helix.* All through the paleo-
lithic period, little change occurred. Nevertheless, there
came a time when the production of the flint tools improved,
and we recognize that this phase lies above that of the pre-
ceding phase, a change recognized by the term "neolithic"
instead of "paleolithic." Then somewhat more rapid prog-
ress is made; and in one or two more turns of the helix we
reach the point where agi'iculture is discovered, where the
villages and towns come into being, and then where writing
is invented. And now successive turns rise more rapidly from
each other, and we see that it is necessary to consider the
meaning of this vertical component of our diagram.

Since time is represented by the angular co-ordinate, the
vertical component must be the level of achievement, dif-
ferent according to the field of accomplishment selected-
sculpture, architecture, engineering skill, literature, and so
forth. This is the level of civilization as a whole and not
that of any single component. In many fields, there is little
or no secular improvement— in the art of sculpture, for in-
stance—and there must, therefore, be some factor in the ver-
tical component of the helix that has steadily increased and

* The frontispiece is an attempt to realize this graphically. It is a
photograph of a helix of wire. The lower coils are close together, and,
as they rise, they are distorted and even overlap, but finally the vertical
component increases rapidly.

THE HELIX OF HISTORY 41

now determines the progress of civilization as a whole. This
component can only be that of progress in the field in which,
according to Sarton, it has definite and unquestionable
meaning, that of "systematized, positive knowledge," that is.
Science.

Through the ages we see an increase in man's understand-
ing of nature and his control of natural forces. Astronomy
started as astrology, but this involved the observation of the
positions of the heavenly bodies and thus led to the astronom-
ical determination of time and the establishment of a calen-
dar. Moreover, fiom obser\ ations of the stars it was possible
to form an idea of world geography; and this made possible
the development of navigation away from the coasts. Prac-
tical metallurgy led into chemistry, for which alchemy played
the part that astrology played for astronomy. Through a
vast amount of suffering man attained some know^ledge of
anatomy, because of his need for surgery, and finally of
physiology. Thus, step by step, science advanced through
the ages until we reached the seventeenth century. Then
there was a sudden and definite change in the rate of learn-
ing. The experimental method of research ^vas discovered,
and the advance in scientific method and knowledsre sud-
denly became much more rapid. The cause and nature of
this sudden change are discussed later. Indeed, the nature
of science and the methods of experimental inquiry form the
principal subjects of this book. In the meantime, we may
complete our picture of the helix of history by realizing that
it shows a steady increase in the separation of the coils and
then, suddenly, after the discovery of the methods of experi-
mental science, springs upward in an almost vertical direction.

Chapter III
THE METHOD OF SCIENCE

In the previous chapter the great pageant of the historical
past ^vas discussed, in which \\'e can trace the gro^vth of scien-
tific kno^vledge, ^v^hich has followed the rise and fall of civi-
lization but Avhich, nevertheless, has increased as tiine has
gone on, so that it has been the index of all man's progi^ess.

Now let us consider the nature and origin of this scientific
knowledge. But first it is necessary to re\'ise and clarify the
implications of some earlier statements. Progiess in civiliza-
tion has been said to correspond to an increase in scientific
knowledge and to its application to the social and economic
life of the time. Up to the present, science and technology
have been treated as synonymous; but we find upon investi-
gation that they do not have a common origin.

Scientific knowledo^e arises from certain characteristics in
the mind of man ^vhich cause him to seek to understand
phenomena. Technology arises from an entirely different
motive— the desire to acquire more or better things. The
flint knapper was not a scientist; he '^vas a technologist, and
he proceeded by the immemorial method of technology-
practice and invention. The science of flint knapping ^vould
involve a study of the structure of the flint, of those proper-
ties which produce the conchoidal fracture characteristic of
the substance, and this was far beyond the ability of anybody
who wished to make flints for practical use as tools. In
practice, technology advances to an astonishing extent in the
absence of any accurate knoTvledge of the principles on ^vhich
it is based. ^Vhen the modern building contractor under-
takes the erection of a building, he makes a survey of the
materials he will need and arranges for the delivery of the

THE METHOD OF SCIEXCE 43

necessary quantity as required. But a primitive builder will
fetch his materials as he wants them, obtaining more and
more until the building is finished, without any preliminary
survey of the quantity required. Modern industry makes use
of statistical surveys and cost analysis. Only a fe^v years ago
such aids to operation ^vere unknots n. Such matters have no
relation to the technical skill of the craftsman; the builders
of the Pyramids and the goldsmiths ^vho wrought the coffin
of Tutankhamen ^vere craftsmen of superb skill, but they
probably did little calculating before they started work.

Technology has usually proceeded by trial and error. The
practice of photography, for instance, preceded any knowl-
edge of the theory of the photographic process. Photographic
materials w^ere made by trial, and to this day the making of
photogiaphic materials is in advance of the understanding of
the basic science of the subject. Advances in photographic
science have pro\'ided a "^vorking theory of the light sensi-
tivity of photographic materials, of ^vhat happens to them
during exposure, and of ^vhat happens to them during de-
velopment. But the relationship bet^veen the operations of
making the photographic emulsion and the properties of the
resultant emulsion is not yet understood. Only a ie^v years
ago practically nothing was kno^vn of the "^vay in "vvhich cer-
tain dyes sensitize silver bromide in photographic emulsions
to the regions of the spectrinn which the dyes absorb. The
matter is being elucidated, but ignorance of it did not pre-
vent our discovering great numbers of dyes and applying
them to the sensitizing^ of silver bromide.

There comes a point in technology, however, where prog-
ress is sloAV or even stops for lack of knowledge of the funda-
mental science. Progress in photogiaphy has been greatly
accelerated by our luiderstanding the physical chemistry un-
derlying the photographic process.

Progress in engineering is dependent to a very great extent
on fundamental physics, on ^vhich all engineering is based.
But the invention of the steam engine ^vas not dependent
upon the understanding of Ne^vton's work, nor was the de-

44 THE PATH OF SCIENCE

velopment of the gasoline engine dependent upon the under-
standing of Carnot's cycle. It is easier to improve engines if
you understand thermodynamics; but the men ^vho invented
the engines did not understand thermodynamics, and many
of those A\ ho improved them almost to the present level did
so ^vithout any knowledge of the scientific principles which
underlay their ^vork. The greatest inventor of all time,
Thomas A. Edison, was not a scientist and was not even
interested in science. He w-as interested in doing: thinQ^s and
not in understanding how he could do them. Nevertheless,
the advance of technology has been greatly stimulated by the
advance of scientific knowledge and, to a considerable extent,
has been made possible by that advance. Edison, for in-
stance, observed the Edison effect; that is, from a glowing
filament in a lamp, a current would pass through the vacuum
to a second filament in the same lamp. But Edison was not
interested in studying this further or, at any rate, did not
do so, and it w^as left for Owen Richardson to sho^v the origin
of the current and for J. A. Fleming and his successors to
design the electronic tubes, on which so much of our recent
electrotechnology is based. The ^vhole technology of elec-
tricity is based on scientific discoveries, and without those
discoveries the technologists ^vould probably never have ap-
plied electrical methods, because there is no convenient
source of electricity in nature except the intractable lightning
flash and the phenomena of static electricity, which have
even at present very little application in practice.

Technology even today proceeds by trial and error, the
experimental method, but as a result of our knowledge of
pure science, we have learned to experiment more actively
and more efficiently. Science suggests to the technologist ex-
periments by means of which progress can be made. Tech-
nology is not an offspring of science; it is a separate activity
of mankind, but it is very much stimulated by the other
human activities of scientific study and research.

The special activity of mankind which we call science began
as a classification of facts. Certain types of men have a desire

THE METHOD OF SCIENCE 45

to classify facts into patterns, to associate facts ^vith each
other and thus understand, as they ^vould say, the connections
bet^veen the facts. This understanding usually arises from
repetition of the same facts in the same order. There is no
difficulty, for instance, in associating the phenomenon of rain
with the presence of clouds, and one of the earliest facts of
Tvhich man ^vas a^vare must have been that rain comes from
the clouds. It was much later, however, w^hen he realized
that lightning and thunder were also natural phenomena
associated with the clouds; and primitive man does not seem
to have associated them at all ^\dth rain.

The beginnings of science, then, are to be found in a system
of classification in ^vhich different facts are associated and
regarded as being in the same classification or, as it is usually
put, as being due to the same cause. Very often, early man
was ^vrong in his classification, and his association of facts
proved later to be incorrect; such incorrect associations have
persisted through the ages. AVhen such incorrect associations
have been held by many men for many years, w^e often call
them superstitions^ and they become so rooted in our minds
that they are very difficult to eradicate.

One of the most interesting systems of incorrect associa-
tion of facts is known as magic. One of the earliest facts of
which an animal becomes conscious is that its o^vn body is
not functioning normally. Usually the trouble corrects it-
self and the animal recovers. As soon as man began to reason,
he must have tried to find remedies for his bodily disorders;
and those remedies were associated ^\ ith his daily routine and
especially, perhaps, with food. If a plant can make you ill,
cannot the same plant or another make you well? If you eat
the same plant, you are using a homeopathic medicine; if you
eat a different plant, an allopathic medicine. If you simply
hang the plant around your neck, you are employing magic.
In so far as men have kno^vledge, they use that knowledge.
AVhere knowledge fails, they attempt to supply it, and ^ve
term the attempt magic. Thus, in the medical w^orks of the
Egyptians, anatomical and surgical knowledge and the diag-

46 THE PATH OF SCIENCE

nosis and treatment of disease are interminorled with magrical
spells. Among primitive peoples, magic has always played a
great part, and it is perhaps a little difficult for us to realize
how deeply the principles of magic are entrenched in the
thought and history of man.

Sir J. G. Frazer * analyzes the principles on which magic
is based: first, that like produces like or that an effect re-
sembles its cause; and, second, that things which have once
been in contact with each other continue to act on each other
at a distance. From the first of these principles, which he
calls the lazv of similarity, it is inferred that a man can pro-
duce any effect he desires merely by imitating it. If a savage,
for instance, wants a good crop, he will take care to have it
sown by a woman who has many children; or, if a witch
doctor, as the practitioners of primitive magic are called,
wants to hurt a man, he will make an image of him and then
destroy it in the belief that just as the image suffers, so does
the man, and when it perishes, he must die. From the second
principle, it is inferred that whatever is done to a material
object will affect any person with whom the object was once
in contact. Most savages are very careful to burn any hair
they cut off or the parings of their nails, lest an enemy inight
use them to do them harm. And in some African tribes,
anything once touched by the king must be carefully de-
stroyed. The negative principle, corresponding to the
principle of similarity, is the great widespread la^v of taboo,
which governs the things that a man abstains from doing
lest, on the principle that like produces like, they should
spoil his luck. The Eskimo boys, for instance, are forbidden
to play cat's cradle because if they do so their fingers might
in later life become entangled in the harpoon line. The
principles of inagic are so 'widespread that almost all the
acts of primitive peoples are connected with the production
of good luck or with the avoidance of ill luck. These wide-
spread principles are by no means extinct among us today.

* J. G. Frazer, TJie Golden Bough, p. 11, one-volume edition, New
York, The Macmillan Company, 1922.

THE METHOD OF SCIENCE 47

On careful analysis many of our beliefs will be found to be
essentially magical in origin though we are generally no
longer conscious of the sources from \vhich those beliefs have
sprung. Malinowski * considers that Frazer overstresses the
ritual aspect of magic and that it is the practical aspect of
magic as an answer to necessity that explains its persistence.
A sick man or a bereaved woman feels that something must
be done to assuage the hurt; and, if no effective remedy is
available from knowledge, magic takes its place.

An even greater factor than magic in the history of man
has been the development of religion. Very early man ob-
served that his food and well-being were closely connected
^vith natural phenomena, such as the cycle of the seasons,
which we know to be due to the movement of the earth
around the sun. He, ho^vever, catalogued the facts that he
knew under the hypothesis that natural phenomena ^vere due
to the actions of intelligent beings made in his image; and
he gave these invented beings jurisdiction over gioups of
natural phenomena, so that there were gods of the earth, the
sky, the sea, and minor gods of trees, rivers, and mountains.
Sometimes psychological phenomena ^vere classified in the
same way. There were gods of love and ^var, of terror and
sorrow, and thus ^vas built up the structure of religion. AV^hen
the gieat prophets came— Buddha, Jesus, and Mohammed—
their philosophy drew on this structure and their followers
incorporated much of the earlier religious belief iYi the sys-
tems of philosophy that were founded on their teaching. To-
day, among what ^ve term religious belie js, we continually
encounter groups of associations that started as hypotheses to
be used in the classification of natural phenomena. Christian
hymns still repeat the belief that the crash of sound that
follows the discharge of electricity from a cloud to earth is
the voice of a god. But basically religion fulfills a need that
men have always felt, the need for knowledge of the funda-
mental issues of existence. How did the world come into

* B. Mahnowski, A Scientific Theory of Culture, p. 199, Chapel Hill,
University of North Carolina Press, 1944.

48 THE PATH OF SCIENCE

beinof? Whence did man come? And where does he 2^0 after
death? These are the problems of religion that differ from
magic in subject matter,* since magic relates to the specific
problems of everyday life— to health and sickness and the
supply of food and water.

Bit by bit, in spite of mistakes and false starts, man suc-
ceeded in building up a series of associations among the facts
he knew that bore the only test having any value, that of
confirmation by direct observation or experiment. Through-
out the greater portion of recorded history, the material froin
which scientific conclusions were drawn was the observation
of naturally occurring facts. Astronomy was, of course, de-
rived purely from observation. Medicine in the sense of
anatomy and pathology was the observation of the structure
of the body and of disease. The experimental sciences were
almost non-existent before the seventeenth century, when
direct experiments were made to ascertain facts that could
not be observed without such experiments. As A\e have
already seen, it was the development of experimental science
that produced changes in the evolution of society that ^vere
so startling compared with those that had occurred previously.

The method of science is the accumulation of facts, partly
by direct observation of naturally occurring phenomena-
aided, of course, by all the instrumental appliances that have
been developed to assist the use of the senses— and partly by
the production of new facts as the result of direct experiment.
These facts are then classified in such a way as to sho\\^ their
interrelations and coincidences and are built up into a body
of ideas that are considered valid by the experts in the sub-
ject. This body of ideas is itself the science of which they
form the material. Thus the science of physics consists of
a gToup of physical ideas accepted as valid by physicists; the
same is true for chemistry, for biology, and the other sciences.
These groups of ideas are undergoing constant change. As
new facts accumulate, they are integrated into the old ideas

* Malinowski, loc. cit.

THE METHOD OF SCIENCE 49

or, if necessary, into new ideas; sometimes new facts force the
revision and change of accepted ideas. The methods used in
different branches of science are to some extent peculiar to
each, and the tests required to justify the acceptance of an
idea as vaUd are selected by those working in each branch.
Thus, as Polanyi says, "Science consists of autonomous
branches, ruled by their several systems of ideas; each of these
is continuously producing new minor propositions suitable
for scientific verification; and by these verifications they are
being steadily strengthened and revised." *

The methods of scientific research are analyzed by W. H.
George in his book, The Scientist in Action.-f He defines
scientific research as a form of human action, and science,
that is, ordered knowledge, as a product of the activity of
human beings. But it is not a product of the activity of all
human beings; it is only a special and very limited class
of human beings Avho can produce scientific knowledge.

The first qualification of a scientist is often said to be curi-
osity, that is, a scientist is interested in the observation of
facts; but this alone does not distinguish scientists. If it did,
there w^ould be far more scientists than there are, since curi-
osity is a very common characteristic of human beings. A
scientist not only observes facts but has an instinctive desire
to classify them and set them in order. It is by this classifi-
cation of facts that science progresses.

The mere observation of facts is not by any means a simple
operation. To be of value, facts must be generally received
by different observers as true or acceptable; and this, of
course, accords with the practice of scientific research, that
facts about which there is any doubt must be checked by
different observers and discrepancies must be reconciled. If
various observers cannot agree as to the facts, it is customary

* M. Polanyi, Rights and Duties of Science, p. 175, the Manchester
School of Economic and Social Studies, Manchester, England, October
1939.

f \V. H. George, The Scientist in Action, London, Williams and
Norgate, Ltd., 1936.

50 THE PATH OF SCIENCE

to put those facts in what we may term a "suspense account,"
reserving judgment of their validity until a consensus by
qualified observers is reached. In the history of science,
many observations have been published that were not ac-
cepted immediately as accurate. Some of them were later
agreed to be erroneous; many were confirmed by further
study.

A requirement for this agreement between different ob-
servers is that they be critical of the method of observation
employed. It is well known to psychologists, for instance,
that the reports of different observers of a series of incidents
may disagiee. George quotes an experiment by A. AV. P.
Wolters * in which a disorderly incident was deliberately
introduced into the middle of a lecture he was giving on
observation. The students ^\ ere then asked to write at once
a detailed account of what had occurred. An accurate and
full report would have contained ten essential points of de-
tail. The average number of points correctly reported was
3,5, and the reports contained many completely false state-
ments, it being impossible for some of the details to have
occurred in that particular room. The cause of these dis-
crepancies is, of course, the unanticipated nature of the
events. Reliable observations can be obtained only if the
observer is paying attention to the action observed. The
more suddenly the phenomenon happens and the more un-
expected it is, the less likely are reliable observations to be
made.

A second factor in observation is that the observer will see
more if he is not only looking at what is to be observed, but
looking for it. A histological section under a microscope
will convey no information to one who is ignorant of minute
anatomy. I recall once studying an x-ray photograph on an
illuminator. The photograph had been taken as a test of the
photographic plate. Some one looking over my shoulder
said: "Isn't that a beautiful photograph?" To this I replied

* George, op. cit., p. 79.

THE METHOD OF SCIENCE 51

at once: "I was thinking it was very bad." W'e were, of
course, ol^serving different things. He was interested in the
general appearance of the radiograph and would have been
equally pleased ^vith any photograph of the same subject. I
was critically observing the rendering of detail in the shadows,
in ^vhich respect that particular photographic material ^vas
unsatisfactory.

Observations must be controlled by knowledge of the
errors which the sense organ itself may introduce in the ob-
servation. The W'hole class of optical illusions, for instance,
may produce false conclusions. The unaided ear, and espe-
cially the untrained ear, cannot be trusted to give reliable
information as to sounds. There is also the question of
personal error. The observer must recognize what H. G.
Wells calls "the limitations of the instrument," not only as
regards the sense organ but also, as Wells uses it, in regard
to the mind itself.

In scientific research, observation is not always direct;
much use is made of instruments and apparatus. Instead of
the eye, the photographic film or the photoelectric cell may
be used. Sound vibrations may be measured electrically.
Instruments have many advantages over the unaided senses.
The microscope makes very small things visible. The tele-
scope collects light from a large lens surface and then enables
magnification to be applied. Moreover, such instrumental
methods of observation enable us to overcome the limitations
imposed by the recording system of the brain. It does not
matter how unexpected or ho^v rapid and transient a phe-
nomenon is, if we have a photographic record of it. A
motion picture of the disturbance in the classroom ^vould
have enabled all observers to agree on the facts after they had
seen it several times. The sudden flash of the lines in the
spectrum at the second contact point of an eclipse can be
recorded photographically and studied at leisure.

Observations made with instruments are essentially judg-
ments of coincidence. The observer measures a length by
seeing the point at w^hich the object to be measured comes

52 THE PATH OF SCIENCE

into coincidence with a mark on a scale, or weighs by ob-
serving tlie weight which will enable the pointer of the bal-
ance to swing uniformly over the center of the scale. The
impersonal data, therefore, that form the basis of scientific
knowledge come from judgments of coincidence, and it is
only when such determinations of coincidence can be made
that general agreement between different observers is found.
When men are asked to judge the values of truth or beauty,
goodness or merit, there is no approximation to universal
agreement; but different observers will agree when they are
making coincidence observations.

It is true that the precision of coincidence observations is
limited. A scientist is sometimes asked how he can tell that
certain points really coincide. The answer is that the word
really has no meaning. Within certain limits, fixed by the
sensitivity of the instrument and by the skill of the indi-
vidual in judging coincidence, different observers will agree.
As Newton wrote in a letter in 1675, dispute about what can
be observed in an experiment "is to be decided not by dis-
course but by new trial of the experiment." *

In the observation of facts, the scientist and, indeed, all
human beings select some of the facts for attention and do
not treat all of them in the same way. Scientific facts repre-
sent, indeed, only a very small portion, selected from all the
facts that could be observed. The selection depends upon
the previous knowledge and upon the interest of the observer.
Suppose, of two men entering a room, one was extremely
thirsty, and the other was a painter interested in modern art.
The first on entering the room ^vould see the jug of water on
the table, and, whether or not his manners would restrain
him from making a dash at it, the jug ^vould certainly be
the center of his interest until his thirst was satisfied. The
artist, not being thirsty, would probably not be conscious of
the existence of the jug. His interest might be attracted by
a picture on the wall. An extreme case of this difference in

* George, op. cit., p. 100.

THE METHOD OF SCIENCE 53

interest and experience is shown when an animal, a dog, for
instance, enters a room in which people are sitting. The
dog's reaction to his new environment is quite different from
that of any human being.

The scientist in general, being by definition a person curi-
ous concerning facts and eager to record and arrange them,
observes phenomena somewhat differently from other human
beings. The parody addressed to Huxley * by Miss May
Kendall comes to mind:

Primroses by the river's brim
Dicotyledons were to him.
And they were nothing more.

But when scientists are definitely making observations in
practical research, they go much further. They deliberately
choose certain facts for observation, facts which in some way
fit into the pattern in which they are interested. When a
scientist has selected the facts which he wishes to observe
and has made the necessary coincidence observations, for
instance, by means of instruments, he classifies the facts. In
biology, and especially the more general biological work
which comes under the heading of natural history, classifi-
cations sometimes remain simple classifications; at any rate,
for a long period. Thus Charles Darwin classified enormous
numbers of facts relating to the properties and habits of
animals of many kinds in all parts of the w^orld. But, even-
tually, the scientist, if he is really a scientist, desires to cover
this whole classification by some statement or formula into
which the observations can be integrated as a whole. Darwin,
who had collected great numbers of facts relating to the
existence and survival of species among animals, finally
evolved his doctrine of natural selection and embodied the
whole in his great book. On the Origin of Species. It must
always be remembered that it is the observed facts themselves
that have validity, and the formulae or statements about

* Leonard Huxley, Life and Letters of T. H. Huxley, p. 112, Vol. I,
London, Macmillan and Co., 1900.

54 THE PATH OF SCIENCE

them are merely convenient methods of summarizing them,
classifying them, and suggesting the possibility of the observa-
tion of further facts. Facts are the foundation of science
however they may be interpreted. As Faraday said:

I cannot doubt but that he who, as a wise philosopher,
has most power of penetrating the secrets of nature, and
guessing by hypothesis . . . will also be most careful . . .
to distinguish that knowledge which consists of assumption,
by which I mean theory and hypothesis, from that which
is the knowledge of facts and laws, never raising the
former to the dignity or authority of the latter nor con-
fusing the latter more than is inevitable with the former.*

The patterns into which scientific men fit the facts which
they have observed are generally known as hypotheses or
theories. In practice, a theory is an elaborate hypothesis that
deals with a wider range of facts than does the simple hy-
pothesis. In the initial stages, especially before verification,
what is later called a theory is often called an hypothesis. At
the point where an hypothesis is formed after the considera-
tion of the observed facts, the scientist ceases to consider only
the facts and proceeds to draw on his imagination. He at-
tempts to see some connection between the facts he has ob-
served, to form some pattern that he can generalize into
which they fit. Then he examines his generalization to see
whether any facts relevant to the subject and of the type
which he has been observing invalidate that generalization.
This is the very important verification of a theory; an un-
verified theory is merely an initial guess and is not accepted
as valid. Further verification is obtained by deducing from
the theory results leading to facts that can be tested by ob-
servation. If this test is met and the facts are established,
the theory is considered to have strong support and to be
a scientific theory having validity until facts are discovered
that are not consonant with it. Thus we see that a scientific
theory is formulated by the examination of a selected gioup

* Michael Faraday, Philosophical Magazine, 24, 136 (1844). (Quoted
by George.)

THE METHOD OF SCIENCE 55

of facts in accordance with certain basic ideas that may be
termed the postulates. It is necessary that these postulates
should be logical and that they should be clear in the sense
that they can be reasoned about. Moreover, in scientific
work stress is laid on the simplicity of the postulates and on
the postulates being as few in number as possible. The
simplicity rule is always applied when a choice must be made
between two theories. Newton says: "Nature is pleased with
simplicity." * This is so well recognized in scientific work
that there are classic statements of the rules of systematic
inquiry. William of Occam, the English philosopher of the
fourteenth century, expressed it in a phrase which is known
as ''Occam's razor." In Hamilton's translation, it is: "Neither
more, nor more onerous causes are to be assumed than are
necessary to account for the phenomena." Newton's version
in his Rules of Philosophizing reads: "No more causes of
natural things are to be admitted than such as are both true
and sufficient to explain the phenomena of these things."

In practice, this demand for simplicity competes with the
further requirements that the theory shall fit as many types
of fact as possible. The very simple rule that Robert Boyle
gave for the relation between the volume and the pressure of
a gas holds for only a limited range of pressures. In order to
cover a wider range, it must be complicated by the addition
of the term suggested by van der Waals.

George points out that, provided the postulates of a theory
are sound, it does not matter if they appear absurd or con-
trary to common sense. Almost everything new appears ab-
surd. Absurdity is associated primarily with the unusual.
The headdress of a Zulu rickshaw man does not appear ab-
surd to a resident of Durban, but it would excite a great deal
of interest and amusement in San Francisco. And the story
of the ridicule excited by the first umbrella should warn us
against regarding the appearance of absurdity as having any
relation to value. Both the quantum theory of Planck and

* George, op. cit., p. 240.

56 THE PATH OF SCIENCE

the relativity theory of Einstein appeared completely absurd
when introduced. Ralph Fowler wrote in Nature in 1934,
"Nothing could have exceeded the apparently wild extrava-
gance of de Broglie's first work on electron waves which led
directly to quantum mechanics." This does not mean that
the formulator of a scientific theory would try to make his
theory appear absurd or contrary to common sense. It means
only that common sense has nothing whatever to do ^vith
scientific theorizing or with the practice of scientific research.
Common sense is a judgment depending on common beliefs
rather than logic. As Enriques says, "It is a prudent safe-
guard for whoever w^ants to spare himself the critical study
of scientific expressions." *

In an analysis of the part played by theory in the develop-
ment of science, Margenau f divides the world of the scien-
tist into two parts: sense data and constructs. The sense
data we have discussed as facts or coincidence data; the con-
structs are concepts invented by certain rules and bearing
certain relations to sense data. We look at a line in the
spectrum and say that it is blue. We associate this blueness
with the existence of light and of light of a certain wave
length. These ideas are constructs. Other constructs are, in
mathematics, number^ integral, space; in chemistry, element j
atom, compound, valence bond; in physics, electron, electric
field, mass. The ideas that form the body of scientific knowl-
edge deal primarily wdth these constructs, which represent
sense data symbolically and have properties that permit their
discussion logically and wdth the aid of mathematics. These
are a scientist's operations:

The scientist assembles his facts, he translates his data into
constructs that he invents for the purpose according to cer-
tain rules that experience has shown to be useful. He then
assembles these constructs, frequently using the language and

* Enriques, Problems of Science, English translation, p, 329, London,
1924. (Quoted by George, op. cit., p. 247.)

f H, Margenau, "Theory and Scientific Development," Scientific
Monthly, LVII, 63 (1943).

THE METHOD OF SCIENCE 57

methods of mathematics, into a theory and, finally, he verifies
the theory by deriving from it new conclusions that can be
determined by observation. The evolution of the scientific
method has depended upon the realization of the importance
of these operations and, particularly, of the importance of
verification before any theory is allowed to fit into the exist-
ing pattern of scientific knowledge.

When a set of scientific facts can be summarized by a simple
statement and, especially, when that statement can be ex-
pressed in a mathematical form, it is said to be a law. Physi-
cal observations generally are classified by means of laws that
can be expressed in mathematical form.

When a set of observations is finally reduced to a law or
mathematical form, the scientist who succeeds in the effort
feels a sense of satisfaction and receives the approval of his
scientific colleagues, especially if the formula that he has
developed covers a wide field of previously unreduced ob-
servations. Sometimes, on the other hand, new observations
which would be expected to fit into a known formula do not
do so. This raises questions as to whether the observations
are erroneous, whether some factor has been ignored, or
whether the formula is not broad enough to include the new
observations. The discovery of facts that are fundamentally
new and that require a considerable revision of established
laws to represent them is an important event in the history
of science and one that is frequently misunderstood, particu-
larly by the layman.

In the nontechnical interpretations of science, whether
written by laymen or by professional scientific w^orkers, the
nature of scientific theory and law is very rarely borne in
mind and made clear to the reader. In any case it is difficult
to make the layman understand the nature of a scientific law.
This is partly perhaps because of the unfortunate name that
has been given to it.* We speak of "laws" in various senses—

* The origin of the term is discussed by E. Zilsel in his article, 'The
Genesis of the Concept of Physical Law," Philosophical Review, LI,
245 (May 1942). He points out that the roots of this concept go back

58 THE PATH OF SCIENCE

the laws of men, which are enforced by police power; the laws
of God, which are thought to be enforced by supernatural
authority.

When a scientist speaks of a law, the public thinks that, if
the law is disobeyed, some penalty will follow. But a scien-
tific law is not an order which must be obeyed; it is a state-
ment of fact. There is no way of obeying or disobeying it,
and since disobedience is impossible, there is no penalty.
The so-called laws of health can be disobeyed; they are state-
ments of desirable action that have been formulated. But
the law of gravity cannot be defied. If a man jumps out of
a window and is caught in a net, he is not defying the law of
gravity; he is acting according to the law of gravity.

The feeling that there is some connection between natural
law and divine law has given rise to the idea that, in his
establishment of laws^ the scientist is approaching some form
of absolute truth— that the whole process of scientific re-
search, in fact, is the uncovering of truth and, if we only
knew enough, we should be able to approach to a knowledge
of absolute truth concerning all things. This idea leads to
the personification of the existence of nature^ an order of
things external to ourselves concerning which generalizations
may be made. Such a personification is often to be found in
the writings of scientific men, especially those written for lay-

to antiquity. The divine lawgiver is the central idea of Judaism, and
since God in addition is the creator of the world, it is easy to under-
stand that the idea arose of his having prescribed certain prohibitions
to the physical world. Thus Job says that God made a law for the rain.
In classical antiquity also is to be found the idea that physical processes
are enforced by gods.

The term law was used by Francis Bacon as synonymous with form,
and Bacon probably derived the term from the Bible. Kepler used the
word to some extent, and Descartes adopted the whole concept of nat-
ural law referring to the laws that God has put into nature, arguing, in
fact, that natural laws must be immutable because God and his opera-
tions are perfect and immutable. The word in its present sense owes
its popularity primarily to its adoption by Newton, who, however, used
the term without any tinge of metaphysics and simply as the description
of a phenomenon.

THE METHOD OF SCIENCE 59

men. But nature is only the summation of observed facts
fitted into patterns which resume and classify them.

The approach of a scientist to the phenomena which he
observes may be realized perhaps by means of an analogy.
Suppose you enter a room and see a man playing a violin.
You say at once that this is a musical instrument and is pro-
ducing sound. But suppose that the observer were abso-
lutely deaf from birth, had no idea of hearing, and had never
been told anything about sound or musical instruments, his
whole knowledge of the world having been achieved through
senses other than hearing. This deaf observer entering the
room where a violinist was playing would be entirely unable
to account for the phenomenon. He would see the move-
ments of the player, the operation of the bow on the strings,
the peculiarly shaped instrument, but the whole thing would
appear to him irrational. But if he were a scientist inter-
ested in phenomena and in their classification, he would pres-
ently find that the movement of the bow on the violin pro-
duced vibrations, and these vibrations could be detected by
means of physical instruments, and their wave form could be
observed. After some time, it might occur to him that the
vibrations of the strings and violin would be communicated
to the air and could be observed as changes of pressure. Then
he could record the changes of pressure produced in the air
in the playing of a piece of music, and by analyzing the record
could observe that the same groups of pressure changes were
repeated periodically. Eventually he could attain to a knowl-
edge of the whole phenomenon of music— the form of musical
composition and the nature of different musical forms— but
none of this would give him any approach to absolute truth
in that he would still be unaware of the existence of sound
as a sense and of the part that music could play in the mental
life of those who could hear.

To the scientist as such, absolute reality has no meaning.
It is a metaphysical conception, not a scientific one. The
scientist neither affirms nor denies it; he merely ignores it.
His purpose in forming abstract ideas is to classify facts ob-

60 THE PATH OF SCIENCE

served through his senses, especially those facts that are ob-
served by the methods of coincidences using instruments.
And his interest in making this classification is greatly stimu-
lated, perhaps chiefly stimulated, by the fact that from it
he can deduce the possibilities of observing and correlating
other facts.

It is impossible to discuss the method of the scientist with-
out giving the impression that it is a purposeful method,
that the scientist is aware of what he is doing, but this is
usually not the case. A scientist does not always collect facts
and deliberately endeavor to fit those facts into a pattern.
He often collects the facts and continuously fits them into
patterns without regard to the process itself. He may select
the facts in which he is interested and attempt to fit them
together into a theory, change his mind and try another
theory, abandon some facts about which he is doubtful, and
replace them by others without any conscious direction of
the operation.* In this process, the scientist draws upon his
imagination and relies upon his intuition. The operation,
in fact, is largely performed by the subconscious mind, and
it is in the facility with which they do this that scientists
differ most in their quality.

In practical scientific discovery and in technology, three
factors are involved, and people vary considerably in their
ability as regards these individual factors. They are theo-
retical synthesis, observation and experiment, and invention.
Psychologically, each involves distinct methods of working
and different types of mind. There is even opposition among
them; that is, it is unlikely that one man wdll excel in more

* Charles Singer (A Short History of Science, Oxford, Clarendon
Press, 1941) points out that scientific articles, and especially scientific
textbooks, give a false impression of the process by which investigators
reach their conclusions. In articles and books, no information is given
on the false starts and discarded hypotheses. The account reads as
though the work ran smoothly to its inevitable conclusion in accordance
with the principles of scientific investigation. As Singer says, "For this
reason, among others, science can never be learned from books, but only
by contact with phenomena."

THE METHOD OF SCIENCE 61

than one direction. It is rare, for instance, for a capable in-
ventor to be a theoretical thinker. Some scientists excel in
their ability to visualize general syntheses and thus evolve
theories. Some excel in their skill in observation or in their
ingenuity in designing experiments. Some have a capacity
for inventing and can design entirely new ways of accom-
plishing their ends. In addition, certain qualities that are
not in any way connected with the scientific mind are, never-
theless, of great value in scientific work. In some fields of
science, organizing ability is valuable, and men who are
outstanding in one of the other factors will be specially quali-
fied to use their organizing ability to promote the progress
of science. Other qualities of considerable value are clarity
of thought and ease of expression, and scientists differ as
much in these attributes as do other men.

Scientists and technologists can advantageously be classified
according to the extent to ^vhich they possess the three scien-
tific factors and the ability to organize. Descartes, for in-
stance, possessed a great power of theoretical synthesis. We
have no evidence that he could experiment or that he showed
any ability to invent. He probably had no opportunity for
organization. Galileo was not only a good theorist but an
excellent experimenter, and some of his work suggests that
he had considerable ability as an inventor. Newton was out-
standing in his capacity for theoretical understanding and as
an experimenter. It is improbable that he had any consid-
erable talent for invention in spite of his work on the tele-
scope and on some other instruments.

Turning to the moderns, we may compare three great
inventors: Lord Kelvin, Thomas Edison, and Elihu Thom-
son. Of these, Kelvin was a most capable theorist, an excel-
lent experimenter, and an outstanding inventor. There is
some reason to believe that he was lacking in capacity for
organization, but his distinction in the other three fields
makes him one of the greatest scientists of all time. Edison
seems to have been purely an inventor. He was not inter-
ested in theory, and his experiments were conducted not to

62 THE PATH OF SCIENCE

obtain knowledge but to make something work. He is, of
course, the inventor par excellence. Thomson was far more
of a scientist than Edison. He made a great number of in-
ventions, and his excellent organizing ability gave him a rank
in applied science that vies with that of Kelvin and Edison.

To a very great extent, the choice of the subject on which
a scientist focuses his attention is a matter of fancy or even of
chance. Moreover, not infrequently he does not succeed in
reaching the end that he sought. Very often important dis-
coveries are made by workers who are not looking for them,
and great advances in science have arisen from a simple study
of natural phenomena.

The great value of applied science has led to a school of
thought that argues that scientific discovery is only justified
by its application and that scientific research should, in fact,
be engaged in only when it can be applied. This doctrine
has been expressed very explicitly by some of the philoso-
phers of the Soviet Union. It is endorsed also by such writers
as Profe.ssor J. D. Bernal, who lays great stress upon the
"frustration" of science, by which term he summarizes his
belief that under a better (in his case, a collectivist) system
of society, the development and, especially, the application
of science would contribute more rapidly to the improvement
of human welfare.* The fact is, however, that it is quite

* The origin of the feeling of frustration by experts such as Bernal is
discussed by F. A. von Hayek (The Road to Serfdom, p. 53, University
of Chicago Press, 1944). Von Hayek points out that "almost every one
of the technical ideals of our experts could be realized within a com-
paratively short time if to achieve them were made the sole aim of
humanity. There is an infinite number of good things, which we all
agree are highly desirable as well as possible, but of which we cannot
hope to achieve more than a few within our lifetime, or which we can
hope to achieve only very imperfectly. It is the frustration of his
ambitions in his own field that makes the specialist revolt against the
existing order. We all find it difficult to bear to see things left undone
that everybody must admit are both desirable and possible. That these
things cannot all be done at the same time, that any one of them can
be achieved only at the sacrifice of others, can be seen only by taking
into account factors that fall outside any specialism."

THE METHOD OF SCIENCE 63

impossible to predict in advance whether any particular
scheme of scientific work will produce results which can be
"applied." No one would have guessed that Lord Rayleigh's
work on the density of nitrogen would have affected street
lighting or that Gregor Mendel's study of peas would be of
the utmost importance in the breeding of cattle; nor, in fact,
was the applicability of these researches recognized for many
years after they had been completed. All the arguments as
to the applicability of scientific research are ex post facto.
Moreover, it is the general opinion of those engaged in the
application of science that there is no frustration in Pro-
fessor Bernal's sense. Bernal believes that when the applica-
tion of a scientific discovery can be seen to have been delayed,
the delay should be ascribed to the faults and weaknesses of
those w^ho might have applied it. The practical men know
that such delays are often due to conditions unknown to the
critics and are unavoidable. Those who have themselves
engaged in the slow and difficult task of translating a labora-
tory discovery into a product available to the public know
how many pitfalls lie in the path. Our difficulty is not
"frustration"; it is ignorance in each individual case. AV^hat
is needed to solve the difficulty is not organization; it is more
knowledge.

The creation of scientific knowledge, the advancement of
science, has been carried out by the methods discussed in this
chapter. The whole operation is so individualistic, it de-
pends so much upon the psychology of the various scientific
workers, that it is difficult if not impossible to direct it, even
if a general agreement were possible as to the goal toward
which it should be directed. Many times in the history of
science the greatest experts have expressed themselves as to
the feasibility of solving certain prqblems or achieving certain
results, and in most cases their decisions have been erroneous.
The application of science can be directed to produce results
of value; the creation of science proceeds from the free opera-
tion of the minds of scientists.

64 THE PATH OF SCIENCE

The scientist, whether his work is the creation of knowl-
edge without thought of its application or is the application
of scientific knowledge to the use of mankind, may adopt as
his motto and guide the words of Thomas Henry Huxley:

Thus, without for a moment pretending to despise the
practical results of the improvement of natural knowledge,
and its beneficial influence on material civilization, it must,
I think, be admitted that the great ideas, some of which I
have indicated, and the ethical spirit which I have en-
deavoured to sketch, in the few moments which remained
at my disposal, constitute the real and permanent signifi-
cance of natural knowledge.

If these ideas be destined, as I believe they are, to be
more and more firmly established as the world grows older;
if that spirit be fated, as I believe it is, to extend itself into
all departments of human thought, and to become co-
extensive with the range of knowledge; if, as our race
approaches its maturity, it discovers, as I believe it will,
that there is but one kind of knowledge and but one
method of acquiring it; then, we, who are still children,
may justly feel it our highest duty to recognize the ad-
visableness of improving natural knowledge, and so to aid
ourselves and our successors in our course towards the
noble sfoal which lies before mankind.

* Thomas Henry Huxley, "On the Methods and Results of Ethnol-
ogy," Collected Essays, VII, London, Macmillan and Co., 1899.

Chapter IV

THE DEVELOPMENT OF THE
SCIENTIFIC METHOD

Having considered die nature of the scientific method, let
us return to the course of human history and study the origin
of that sudden change in the seventeenth century, from which
came the developments in technology and science that have
changed the life of man. W^e have seen that if we judge the
level of civilization by its accomplishments and, particularly,
by the arts of sculpture and architecture, of which the prod-
ucts of many generations of men are available, it appears to
move in cycles.

At the beginning of a cycle, the sculpture and architecture
are primitive or, to use the more appropriate term, archaic.
Gradually the artists improve in the freedom of their style
until a point of high excellence is reached; then degenera-
tion sets in, the style becomes overornate or formalized, and
finally we are justified in speaking of decadence. Yet, while
these cycles recur age after age, varying greatly in details and
in the changes which are of importance in each cycle, there
has been a definite progress in the knowledge and technical
skill of men. This progress is due to the slow accumulation
of technology and even slower accumulation of scientific
knowledge. This slow growth, however, has accelerated
greatly at certain historical periods. Perhaps the traditional
account of the knowledge of Imhotep, vizier of Zoser, the
outstanding king of the Third Dynasty of Ancient Egypt, is
a memory of one of those periods. Imhotep was so greatly
revered that he was deified as the patron god of learning and

was eventually identified with Asklepios, the Greek god of

66 THE PATH OF SCIENCE

medicine. As James Breasted says: "In priestly wisdom, in
magic, in the formulation of wise proverbs, in medicine and
architecture ... he left so notable a reputation that his
name was never forgotten." * As we shall see later, another
period in which great progress was made in science followed
the death of Alexander, in the third century B.C. In the
sixteenth and seventeenth centuries, the growth of modern
science began and has continued to accelerate to the present
day.

The advance in wealth, comfort, and convenience that has
characterized the last three hundred years has been achieved
by a very small number of men, and even today our produc-
tive system is operated by a small group of men trained in
the sciences who utilize the knowledge that has accumulated
largely since the birth of Newton. This group is called "The
Fifth Estate" by Dr. A. D. Little in an essay in which he
discusses their relation to the rest of mankind.f He says:

The fifth estate is composed of those who have the sim-
plicity to wonder, the ability to question, the power to
generalize, the capacity to apply. It is, in short, the com-
pany of thinkers, workers, expounders, and practitioners
upon whom the world is absolutely dependent for the pres-
ervation and advancement of that organized knowledge
which we call science.

Little considered that the effective number of those indi-
viduals was very small. In 1928, he guessed that there might
be less than a hundred thousand in the world.

The history of the development of science is the history of
the evolution of this small body of specialized workers, who
originally took an interest in science as amateurs— those who
loved the subject— and only in recent times became profes-
sionals devoting their whole time to study and the advance-
ment of knowledge.

* James Breasted, A History of Egypt, p. 112, New York, Charles
Scribner's Sons, 1912.

f A. D. Little, The Handwriting on the Wall, p. 253, Boston, Little,
Brown and Co. and Atlantic Monthly Press, 1928.

THE DEVELOPMENT OF THE SCIENTIFIC METHOD 67

The growth of scientific knowledge started so suddenly at
the beginning of the seventeenth century that it might almost
be considered a revolution. As we study the course of this
revolution, it becomes evident that it represents a unique
event in history, and it is difficult to understand why it did
not occur earlier. We can, of course, ascribe the rapid
growth of science in the seventeenth century to the existence
of certain men, Galileo, Boyle, and Newton, for example, but
such individuals are known through all the ages of history.
Why did not the Greeks develop experimental science?
Singer says: "By the end of the fifth century b.c, not only
had philosophical thought taken a scientific turn, but science
itself had emerged as a preoccupation of men set aside from
their fellows." * Later many of the Hellenistic Greeks
of the Alexandrian school— Archimedes, for instance— were
famous for their interest in natural philosophy and for the
inventions that they made. But, in spite of the progress for
which they themselves were responsible, they did not act as
catalysts to set off a sudden growth of science contributed
to by many other men.

Several explanations are possible for the unique phe-
nomena of the seventeenth century. Zilsel studied the emer-
gence of modern science as a sociological process. f He points
out that the end of the Middle Ages was a period of rapidly
progressing technology and of technological inventions and
that in the fifteenth century economic competition and the
spirit of enterprise were emerging from the fetters of the
feudal system. Feudal society was ruled by tradition and
custom, whereas the early capitalism proceeded rationally.
It calculated and measured, introduced bookkeeping, and
began to use machines. Thus at this period the social ban
against personal labor weakened sufficiently to enable edu-
cated men to carry out experiments with their own hands.

* Charles Singer, A Short History of Science, p. 30, Oxford, Claren-
don Press, 1941.

f E. Zilsel, "Sociological Roots of Science," The American Journal of
Sociology, XLVII, 544 (1942).

68 THE PATH OF SCIENCE

In the ancient world, the craftsmen were slaves, and it was
below the dignity of a man of the upper class to handle
materials himself. One profession in Greece was partially
exempt from this rule, that of medicine. A genuine experi-
mental science in medicine and especially in surgery, diet,
and gymnastics was developed by the Greeks. It was em-
bodied in the writings attributed to Hippocrates of Cos, in
which are described the clinical observations of patients suf-
fering from various diseases. The followers of Hippocrates
had the correct scientific method, but the development of
science in medicine was impossible at that time. The true
science of medicine depends upon the advance of physiology',
and the physiology of the human body is so complex that
medicine is still largely empirical.

Instead of developing experimental science, the most popu-
lar Greek philosophers based their views of nature on a priori
assumptions,* and their progress was largely confined to pure
mathematics, especially geometry and the theory of numbers.
Their actual progress in physics was certainly much handi-
capped by their feeling that practical experimental ^vork was
not suitable for a philosopher and thinker. If this seems
strange, we should remember that the feeling existed in some
English universities not more than fifty years ago. Charles
L. Dodgson, better known as Lewis Carroll, wrote a most
violent diatribe against the supply of funds for scientific re-
search at Oxford.f

The social ban on the practical handling of materials prob-
ably did not exist in Egypt, where the rulers not infrequently
boast in their tombs of their accomplishments as engineers
and where some of the priests were noted for their knowledge

* Nevertheless, Thales, the first outstanding Greek scientist, enun-
ciated the fundamental scientific principle of the sequence of cause and
effect. It was largely the influence of the Pythagoreans and of Plato that
diverted the Greek mind from observational and experimental science.

■f Fame's Penny Trumpet, 1876, and also letter to Pall Mall Gazette,
"Natural Science at Oxford," Life and Letters of Lewis Carroll, by S. P.
Collingwood, p. 187, London, Fisher Unwin, 1898.

THE DEVELOPMENT OF THE SCIENTIFIC METHOD 69

of medicine. But many technical developments in Eg)'pt
reached a certain le\'el and then ceased to progress, so that
it is not astonishing that experimental science did not de-
velop to a greater degiee in the Egyptian system.

There is yet another possible explanation for the failure
of the ancient world to discover the method of experimental
science. The individual scientist, hou'ever much he might
discover personally, had no satisfactory way of communicat-
ing it to his fellows before the art of printing was discovered.
He could, of course, write manuscripts, but he had no means
of knowing all those to whom his manuscripts would be of
interest; and it must be remembered that experiinental
science, especially in earlier times, -^vas of interest only to
a very small audience. The specialists today from whom
the great advances come have an understanding audience of
only a few people in the Avhole world. The rest do not read
original papers or, if they do read them, do not realize what
has been done. Realization and acceptance by the scientific
world as a whole await recognition by the specialists and the
explanation of the work by other writers than the original
discoverers. Moreover, interest and ability in writing are
not necessarily correlated with interest and ability in experi-
mental discovery. Newton communicated his results to the
Royal Society in the most casual manner; and, if it had not
been for the insistence of Edmund Halley, it is doubtful if
Ne^vton's collected papers ^vould ever have been published in
such a form that they could produce the effect achieved by
the publication of the Principia.

In the earlier days, there was no mechanism whatever by
which the scientist could find an audience. Nor was he often
interested in finding an audience. The poet, the dramatist,
and even the eloquent speaker might ^vrite for the delight
and interest of his fellow men; the philosopher and teacher
would write; but the experimental scientist ^vould make his
observations, store them in his memory, tell a few of his
friends, whose attitude toward him might be one either of
derision or of uncomprehending veneration, and the kno^vl-

70 THE PATH OF SCIENCE

edge he had won would generally die with him. But after
the invention of printing, scientific works could be repro-
duced so easily that they had a much larger circulation and,
thus, a much greater chance of reaching the few students of
the subject. The great book of Copernicus, for instance,
published when he was on his deathbed, produced an im-
pression on all astronoiners.

The early history of science is only slowly emerging
through the work of the archaeologists. As in other fields
in the history of human understanding, there is little doubt
but that, as we learn more of the ancient world, we shall find
that that world knew more than we realize of the ideas that
we value today. The Dawn of Conscience, which fifty years
ago would have been ascribed to the early Hebrew prophets,
whose work we happen to have in written form dating from
the eighth century b.c, has now been traced by Breasted back
beyond the Old Kingdom of Egypt to a period as remote
from that of Amos as Amos is from us. And so it is not
unlikely that many of the scientific ideas that we meet first
among the Greeks had their true origin in Babylon or in
Egypt or even perhaps in Crete or the Hittite Empire. We
simply do not know the origin of many of the ideas that the
Greeks developed in systematic and written form. Much
valuable work has been done recently on the mathematical
and astronomical ideas of the Babylonians and on the
methods used by the Egyptian engineers, but it is not until
we reach the beginning of the classic era in Greece that we
meet an organized school of science.

The philosopher to whom the Greeks ascribed the earliest
scientific thought was Thales of Miletus, who achieved fame
by his prophecy of the eclipse of 585 b.c, a prophecy which
he was able to make from information on the timing of
eclipses that he had acquired during a visit to Babylon.
Thales worked chiefly on geometry. His pupil Anaximander
was interested in geography and the making of maps. Hera-
clitus of Ephesus, Leucippus of Miletus, and Democritus ad-
vocated a priori views of the "nature of things," and Pythag-

THE DEVELOPMENT OF THE SCIENTIFIC METHOD 71

oras of Samos gave the philosophy of science a mystical turn
that took it far from the path to which it had been directed
by Thales and Hippocrates. Then the whole trend of Greek
thought was revolutionized by the teaching of Socrates. In
his youth, Socrates studied physics, and it is interesting to
speculate as to what ^vould have happened if he had con-
tinued to be interested in science. But Socrates grew im-
patient with the difficulty he found in deducing science from
a single fundamental idea, and turned instead to the teaching
that it is the great business of life to practice the care of one's
own soul. Socrates followed Pythagoras in believing that
reality consists of abstract ideas and that mathematical truths
were divine and illustrated the nature of the mind of God, a
view that has been advocated to some extent by modern
mathematicians. Thus Socrates and Plato, his great follower,
rejected experimental science and established the priority of
mind over matter.

The outstanding philosopher through whom the views of
the ancient Greeks were made available to a later world ^vas
Aristotle, who seems to have combined the po^ver of an orig-
inal and creative thinker with the instincts of a natural
teacher. Aristotle at the age of seventeen left Macedon for
Athens to study under Plato. He worked on mathematics
and physics and wrote treatises on astronomy and physics.
In these fields he followed the platonic philosophy and de-
duced the laws of nature from a priori assumptions, at the
same time adopting the conclusions of the Pythagoreans, who
used arithmetic relations as the basis of the physical world.
Thus he adopted the idea of Empedocles of Acragas in Sicily,
that matter is composed of four elements, each of which is
distinguished by two primary qualities: fire is hot and dry;
air, hot and fluid; water, cold and fluid; and earth, cold and
dry. After the death of Plato, Aristotle began more and
more to abandon these a priori assumptions and to rely on
observation. Perhaps because he was the son of a physician,
he turned to the field of biology, in which he made very rapid
progress. The material that Aristotle ^vrote on biology is in

72 THE PATH OF SCIENCE

Startling contrast to that which he ^vrote on physics. In his
discussion of one set of observations, we might hear Bacon or
Newton ^vriting t^\o thousand years later: "... the facts
have not yet been sufficiently grasped; if they ever are, then
credit must be given to observations rather than to theories
and to theories only in so far as they are confirmed by the
observed facts."

Aristotle was the tutor of Alexander the Great. After the
death of Alexander in 323 b.c, his general, Ptolemy, became
king of Egypt and established his capital at Alexandria. In
Alexandria, Ptolemy II founded the Museum, in which the
personal schools of Plato and Aristotle were developed into
a university. And there arose the greatest school of the
ancient world, in which most of the best scientists of the time
were professors. At the Museum, Euclid established his sys-
tem of geometry, which became the standard of the world
for more than two thousand years; Aristarchus ^vas the lead-
ing astronomer; Archimedes, the outstanding mathematician
and physicist. Archimedes himself came from Syracuse, to
w^hich he returned after his studies in Alexandria. Era-
tosthenes made such precise observations in astronomy that
he was able to calculate the diameter of the earth with con-
siderable accuracy and to elucidate the necessity for the Julian
calendar, with its Leap Year. An even more accurate observer
was Hipparchus, who discovered the precession of the equi-
noxes and established theoretical astronomy in the form that
it retained until the time of Copernicus. The civilization of
Alexandria was, however, doomed to collapse. The history
of the Ptolemies is one of steadily worsening government
until finally the Romans absorbed the fragments of the
Alexandrine Empire.

The prevalent philosophy among the Roman leaders was
Stoicism, ^vhich laid great stress on conduct and duty and
had a completely rigid conception of nature. The Epicurean
philosophy was less widely adopted but had gieater influence
on those few Romans ^vho were interested in science or in
the writing of philosophy. Of these, by far the best known

THE DEVELOPMENT OF THE SCIENTIFIC METHOD 73

is Lucretius, whose book, On the Nature of Things, is often
regarded as a predecessor of our inodern ideas, especially as
Lucretius, follo^ving the Epicurean philosophy, explains the
origin of the entire Avorld as due to the interaction of atoms,
so that atoms are the only reality. The best-known writer on
scientific subjects during the Roman period was the elder
Pliny, who ^vrote a natural history consisting of a vast collec-
tion of observations and statements about animals and plants,
many of them hearsay. Pliny's book formed a kind of en-
cyclopedia that ^vas accepted as the best description of the
natural world for a thousand years; and, although un-
doubtedly it represented progress at the time, its authority
was eventually detrimental to the improvement of natural
kno^vledge.

More and more, the Greek inspiration, which so nearly
achieved the discovery of the experimental method of science,
died out, and, except for the occasional appearance of indi-
vidual thinkers, the world steadily receded into intellectual
darkness. Among these individual thinkers, one of the great-
est was Galen of Pergamum, who ranks with Hippocrates as
the outstanding medical authority of the ancients. Galen
made accurate anatomical and physiological studies of many
animals and worked out a complete physiological system that
survived as the accepted description of physiology until the
sixteenth century. As Singer says, "The ^vhole knowledge
possessed by the world in the department of physiology—
nearly all the biological conceptions, most of the anatomy,
much of the botany, and all the ideas of the physical structure
of living things from the third to the sixteenth century— were
contained in a small number of works of Galen." * The
works were translated into many languages, commented on
by later writers, and reproduced in many forins. Galen be-
lieved that everything was made by God to a particular end,
.a doctrine known as teleology. Because this view fitted the
theological attitude of the Middle Ages so perfectly, Galen
became the authority in his field.

* Charles Singer, op. cit., p. 92.

74 THE PATH OF SCIENCE

The final blow to the study of science came from the de-
velopment of Neoplatonism in Alexandria. This philosophy
derived mainly from Plato, but in part also from Stoicism.
In it, matter was considered to be governed by the Platonic
"Idea" as the soul governs the body, and the factual study of
science disappeared into mysticism. Neoplatonism lasted
only about a century, but it passed into Christianity largely
through the work of St. Augustine. With the coming of
Christianity both the classical science and the classical philos-
ophy vanished, and men devoted their intellects to the study
of theology. Through this period there survived a memory
of the writings of Aristotle, whose alleged views on the struc-
ture of the universe formed the framework on which the
whole of medieval science came to be built. It was held that
Aristotle felt that the stars were noble beings and exercised
influence over the human destinies— a more definite and sys-
tematized astrology than that of the ancients; that the circle
was a perfect geometrical figure; and that the stars, therefore,
must move regularly in circles. Thus arose the doctrine of
determinism, every man's life being assumed to be written
at the time of his birth, a determinism that reached its most
extreme development in the theological field with John
Calvin.

This whole era filled one of the periods of great depression
in the cycles of civilization. It followed the long decay of
the Roman Empire, and for a time the world lay almost pros-
trate, ruined economically by the internecine struggles of
the feudal system and lost spiritually in the squabbles of the
monks, who, in the monasteries, carried on the only intellec-
tual life. Francis Bacon said of the inhabitants of these
monasteries:

Having sharp and strong wits, and abundance of leisure,
and small variety of reading, but their wits being shut up
in the cells of a few authors [chiefly Aristotle, their dic-
tator], as their persons were shut up in the cells of monas-
teries and colleges, and knowing little history, either of
nature or time, [they] did out of no great quantity of

THE DEVELOPMENT OF THE SCIENTIFIC METHOD 75

matter and infinite agitation of wit spin out unto us those
laborious webs of learning which are extant in their books.

The Christian religion, which so greatly modified the mes-
sage of the Greek thinkers as it was transmitted by the
medieval scholars, was of Hebrew origin and was dominated
by a doctrine that had no echo in Greek thought, the doc-
trine of authority. The account of cosmology, history, an-
thropology, religion, and ethics given in the Hebrew scrip-
tures, together with the New Testament, was accepted as the
unquestioned authority for all thought in that field, so that
very soon opinion as to any event was based entirely upon
what could be found on the subject in the Holy Scriptures
or, if there was nothing available in the Scriptures, in the
writings of the fathers, ainong whom Aristotle was often in-
cluded. One may guess that Aristotle would have been very
much astonished at the company in which he found himself.

At the universities, theology and scholasticism predomi-
nated even while the towns were emersrino^ from the intellec-
tual deadlock. Casuistry and fine-drawn distinctions became
a game to which men devoted their lives, and natural phe-
nomena were judged primarily for their theological implica-
tions. It was held always that each individual phenomenon
had been decided by the will of God for a definite purpose
and that the interest of man lay in detecting the purpose
behind the will. Zilsel * says that the first representatives
of secular learning appeared in the fourteenth century in
Italian cities. They were the secretaries and officials of the
governors of the cities who chiefly had to conduct the cor-
respondence and external relations of their employers. To
do this, they strove after perfection of style and the exhibi-
tion of knowledge, making their ^vritings very polished and
their speeches most eloquent. Thus the humanists emerged,
^vho soon, because of their learning, became teachers— in-
structors of their employers' children and then professors at
the universities. In this way, the humanist scholars became

* Op. cit., p. 549.

76 THE PATH OF SCIENCE

part of the university system, and they were proud of their
social rank and their education. They encouraged particu-
larly the study of the ancient languages, in which the writings
of the past were to be found. Curiously enough, much of
Greek thought, the writings of Aristotle, for instance, had
been kept alive during the Dark Ages of Europe by transla-
tion into Arabic and by preservation by the Arabs, who had
swept over Africa and through a great part of Spain. No
true eclipse of learning had occurred among the Arabs, whose
cycle of civilization was in a different phase from that of the
western world. But the Arabic philosophy, and particularly
its devotion to the writings of the Prophet as the source of
authority, provided little stimulus to original thinking. The
writings of many of the Greek authors had been translated
into Arabic through Syriac, which was the language in many
parts of the Byzantine Empire and had from the third cen-
tury replaced Greek in W^estern Asia. Thus, during the
greatest period of Moslem rule in the eighth century, the old
Syriac versions of the works of the outstanding Greek writers
^vere revised, and in the next century many of them were
translated into Arabic. Galen's writings as well as those of
Aristotle were widespread in Arabic translations.

In the fourteenth century, the ancient classics began to be
recovered, Greek was studied, and the Arabic works ^vere
translated into Latin and even retranslated into Greek. It
was not until the fifteenth century that the original Greek
versions were available instead of those that had passed
through the difficulties of the Arabic translation. As has
already been mentioned, the introduction of the art of print-
ing in the middle of the fifteenth century was of the utmost
importance for its influence on science. The first books to
be printed were, ho\\ ever, the classics rather than the prod-
ucts of conteinporary thought. First came the Bible and the
works of authors of theological authority, then the treatises
on law and medicine, and the writings of classical antiquity.
Many contemporary Avriters are, however, to be found among
the early printed books.

THE DEVELOPMENT OF THE SCIENTIFIC METHOD 77

In the fifteenth century, feudalism began to collapse and
to be replaced by capitalism. As Zilsel points out, in feudal
society the castles of knights and rural monasteries ^vere the
centers of culture. In early capitalism culture was centered
in the towns. This capitalism depended on the spirit of
enterprise of the individual, whereas in medieval society the
individual was dominated by the traditions of the group to
^vhich he belonged. With the individualism of the new

society came the beginnings of invention and of scientific
thinking.

In the sixteenth century, the "shaking of the dry bones" *
became much more evident; and, in one field of science after
another, individuals arose who departed from the traditions
of the ancients and began to create knowledge themselves.
Of these, by far the most gifted and original was Leonardo
da Vinci, one of those men of great genius who illuminate
an era. Leonardo was primarily a painter; although his ar-
tistic work was recognized as of the first rank, his greatest
interest seems to have been in mechanical invention. He
was the engineer for several princes of the time, but very
little of his work seems to have been adopted. The fact is
that Leonardo, like many inventors, had the primary ideas
for very many more inventions than he could develop. Even
today it would be difficult for one man, unless he were a great
organizer, to develop to practical success the large number of
inventions sketched in Leonardo's notebooks. A more prac-
tical, though far less gifted, man was Agricola, ^vho ^vrote a
great Avork on metals, in which he set forth the whole tech-
nology of mining.

In the field of biological kno^v ledge, the first necessary step
was to get rid of the idea that the ancient writings of Aristotle
and Galen were authoritative. In the sixteenth century a
man arose who set himself against the ^vhole weight of au-
thority. Born in Brussels in the second decade, Andreas
Vesalius carried out his investigations on the anatomy of the

* Ezekiel XXXVII.

78 THE PATH OF SCIENCE

human body, mainly in Italy. He soon found errors in
Galen's descriptions and corrected them. Despite bitter op-
position, Vesalius at last prevailed; and modern anatomy was
born. Even more revolutionary in its opposition to authority
than the work of Vesalius was that of Copernicus, which
affected the whole thought of man with its new picture of
the universe. This picture was important not only in its
scientific aspect but also from the philosophical point of view.
Before Copernicus, the earth was the center of the universe,
and the teleological point of view, that the earth was created
for man, was a basic idea of both philosophy and theology.
With the abandonment of the earth as the center and the
understanding that the sun was the center of the solar system,
around which the planets revolved, man lost his intrinsic
importance as the being around whom the whole universe
was designed.

About this time, two great optical instruments were in-
vented, the compound microscope and the telescope. The
use of the telescope by Galileo led to his astronomical dis-
coveries. In addition, Galileo throughout his life was
occupied with physical investigations. His work opened
the way to the advancement of the science of mechanics,
especially because he was able to demonstrate experimentally
the incorrectness of a statement ascribed generally, but
wrongly,* to Aristotle, that bodies should fall with velocities
proportional to their ^veights. Galileo showed by direct ex-
periment that this statement is incorrect. The effect of
Galileo's experiment was much greater than the inere dem-
onstration of a new fact might be assumed to be, because it
tended to destroy the authority of Aristotle and to teach men
that the validity of a fact is to be tested by direct experiment
instead of by quotation of any authority, however great.

The first astronomical observation made by Galileo in-
volved another disproof of an Aristotelian doctrine. In
1604, he observed a nova and foinid that, like the stars in
general, it showed no parallax. Aristotle had regarded the
outer zone of the stars as absolutely changeless, whereas the

* V. Nature, 158, 1946, p. 906.

THE DEVELOPMENT OF THE SCIENTIFIC METHOD 79

inner zones of the sun and planets sho^ved changes. Yet here
was a change in the stellar realm! In 1610, Galileo embodied
the early astronomical discoveries that resulted from the use
of the telescope in a little pamphlet, The Messenger of the
Heavens. In it, he described the mountains of the moon,
the great increase in the number of visible stars, and, above
all, the satellites of Jupiter, which offered a model for the
solar system as conceived by Copernicus. These and other
observations produced an attack on Galileo, especially be-
cause much controversy arose as to the habitability of the
moon, the planets, and even the stars. The idea of a plural-
ity of inhabited w^orlds was felt to be contrary to the Chris-
tian doctrines as well as to those of Aristotle. The Inquisi-
tion ordered Galileo to abandon his opinions and to stop
discussing^ them.

Galileo turned to the philosophy of science and discussed
the properties of objects that are primary to the object and
those that depend upon the observer and are secondary to
the object. In this, we see the beginning of a definition of
the special field of science, the subject of our third chapter.
Then Galileo returned to his astronomical work and wrote
his Dialogue between the Ptolemaic and Copernican systems,
in which he endorsed the latter. It was received with en-
thusiasm by the learned but wdth wrath by the Inquisition,
whose edict it clearly infringed. Galileo was arrested, forced
to recant, and after a short period of imprisonment ordered
to spend the remainder of his life in seclusion, a retirement
that he used to the greatest advantage by further discoveries
in mechanics and astronomy. By the time that Galileo died,
in 1642, science had emerged from the medieval world, and
the great revolution in the thought of man was under way.

Promoting this revolution also were two philosophers who
did not themselves carry out any important experimental
work. They were Rene Descartes and Francis Bacon.

Descartes believed that the laws of the universe could be
deduced from certain simple and definite principles and that
these principles apply to all phenomena everywhere. The

80 THE PATH OF SCIENCE

aim of science, therefore, is to understand and define these
basic principles; tliey can then be applied to any special case
that is under investigation. Descartes believed that the cor-
rect principles could be selected by using their clarity as a
criterion; the clearest image would be the most nearly cor-
rect. These ideas, which were similar to those of Pythagoras
and his followers, represent an extension to other studies of
the methods of mathematics, in which Descartes himself made
great advances, applying algebraic methods to geometrical
problems. The method of Descartes consisted in beginning
with the simplest and surest notions and proceeding cau-
tiously to deduce inferences. Descartes realized, of course,
that knowledge is derived from experience as well as from
deduction. In contrast to Bacon, however, he put more faith
in deduction than in experience. Descartes' views on the
philosophy of science represented a very wide break from the
scholastic principles identified with the name of Aristotle;
but they were of a form acceptable to the orthodox scholars
of his time, and they received wide recognition.

Francis Bacon '^vas a very extraordinary man. Born in
1561, the younger son of a British nobleman, he entered
Trinity College, Cambridge, and at the age of eighteen took
up residence at Gray's Inn and became a lawyer. His patron
was the Earl of Essex, and Bacon's career was largely in-
fluenced by that of Essex. When Essex was tried on a charge
of treason. Bacon was one of the Crown counsel, a fact that
gave rise to much criticism. It was not until the accession of
James I to the throne that Bacon had any chance of advance-
ment. Then he was promoted rapidly until, in 1618, he was
made Lord Chancellor. In 1621, however, his enemies dis-
covered that he had been guilty of corrupt dealings, for
which he was sentenced to a severe penalty, largely remitted
by the king.*

The greater part of Bacon's important writings were pub-
lished in the last five years of his life. Bacon was not a

* Compare John R. Baker, The Scientific Life, p. 52, London,
George Allen & Unwin, Ltd., 1942.

THE DEVELOPMENT OF THE SCIENTIFIC METHOD 81

scientist; he took no part in experimental work, and he was
largely ignorant of the great work of the scientists of his
time. Leonardo da \^inci in mechanics, Kepler in astronomy,
Gilbert in electricity, and Vesalius in anatomy had made
great contributions to scientific knowledge, but Bacon ig-
nored all of them in his writing. He was a philosopher but,
above all, he was a writer and advocate. He had a wonderful
gift in his trenchant pen and in his facility of expression,
and he carried the popular imagination with him in his em-
phasis on observation and experiment as against the accept-
ance of tradition. Bacon believed that all fruitful knowledge
was to be based upon inference from particular occasions in
the past to particular occasions in the future, and this he
called the method of inductive reasoning. In addition, he
had two ideas of the utmost importance, ideas that were in-
strumental in producing the scientific revolution. They w^ere
that knowledge is to be acquired primarily by observation
and experiment and that the application of scientific knowl-
edge could lead to practical results of the utmost value.
Bacon overestimated the ease with which scientific knowl-
edge can be obtained, and he fell into an error in ^vhich he
is followed by many today— the error of believing that scien-
tific research can be organized like an engineering project
and that the way to make scientific discoveries is to plan to
make them.

Bacon's first aim was to organize a system for the investi-
gation of nature by observation and experiment. A great
number of observed facts would be collected, and from them
the fundamental processes of nature could be understood.
In this way, he believed, it was possible to attain to "the
knowledge of Causes and secret motions of things, and the
enlarging of the bounds of Human Empire, to the effecting
of all things possible." This w^as a great vision, a new vision
on the earth, and a vision that has been realized. The method
that Bacon suggested for carrying out this idea was the organi-
zation of a research institute,* which he entitled the "House

* Chapter VIII, p. 180.

82 THE PATH OF SCIENCE

of Salomon" and described in his New Atlantis. This in-
stitute contained a series of laboratories for experimental
research equipped with Utopian perfection— caves in the
ground, high towers, buildings on mountains, "the highest
of them three miles at least; great lakes, both salt and fresh,"
pools, rocks in the sea, and bays upon the shore; artificial
wells and fountains; great and spacious houses, in which
could be imitated meteors and sno^v, hail, and rain; orchards
and gardens full of trees and herbs, with soil of various kinds
in which could be produced new plants differing from those
kno^vn.

In these experimental stations and laboratories. Bacon
saw the possibilities of experiments in genetics, physiology,
pharmacology, mechanical arts, metallurgy, optics, crystal-
lography, and all branches of physics and chemistry. This
research institute was to be manned by a great company of
Fello^vs, to whom Bacon, with his passion for detailed or-
ganization, allotted specific functions. Some were to study
written w^orks and to travel in search of kno^vleds^e from
abroad; some were to make observations and experiments;
and some were to carry out computations on the results of
these experiments and to develop theories and devise ne^v
experiments. A noble dream, much before its time and
greatly overorganized, but it led to the idea of co-operation
in the pursuit of knowledge. From it came the impulse that
founded the Royal Society. Martha Ornstein says that
Bacon's description of the House of Salomon "bears to the
cause of learned societies the same relation as does Marx's
'Communist Manifesto' to socialist propaganda. No histori-
cal account can ever be given of gatherings of learned socie-
ties without reference to this, their 'romantick' prototype." *

Bacon, however, was not really describing a learned so-
ciety; he was describing a research institute or, rather, a
group of research institutes. His plan was much more akin

Martha Ornstein, The Role of Scientific Societies in the Seventeenth
Century, p. 43, Chicago, University of Chicago Press, Third Edition,
1938.

THE DEVELOPMENT OF THE SCIENTIFIC METHOD 83

to the Kaiser Wilhelm Institut or to the research institutes
of the U.S.S.R. than to the Royal Society or the Academie
des Sciences. In addition, Bacon believed, as some do today,
that scientific research should be planned with a view to the
application of discoveries to practical human needs. This
has already been discussed,* but in any case it had no im-
mediate effect upon the course of events. The discovery of
the telescope and the microscope and the discussion of the
wonders they revealed created widespread interest, and men
from many strata of society joined the ranks of the amateurs
studying new experiments. Many of these amateurs be-
longed to the English aristocracy, foremost among whom was
Robert Boyle, a younger son of the great Earl of Cork. Boyle
devoted his whole life to scientific research and discovered
the relation between the pressure and the volume of a gas,
still known as Boyle's law. When a young man, Boyle asso-
ciated with a group of enthusiastic experimenters, to ^\ hich
he refers in a letter as "our invisible college." The meetings
of this group were greatly interrupted by the Civil W^ar, and
it was not until the restoration of the monarchy that life in
London could move on the old lines. But in 1660 a move-
ment was made toward a definite org^anization of this interest
in experimental philosophy, and in the next two years a
society was formed that in 1662 was incorporated under the
patronage of King Charles II with the name of the Royal
Society.

Among those who founded the society were Robert Boyle,
John Evelyn, and Sir Christopher Wren, who, though com-
monly thought of only as an eminent architect, was the most
widely accomplished man of his time. Among the subjects
in Tvhich he was a recognized authority were mathematics,
astronomy, meteorology, and anatomy.

With the formation of the Royal Society, organization
entered the history of science. For the first time, there were
a nucleus and a meeting place for those interested in experi-

* Chapter III, p. 62.

84 THE PATH OF SCIENCE

mental science, a method of exchanging vie^vs, and, what was
perhaps even more important, a method of publication. The
first task of the Royal Society was to begin publication of its
Philosophical Transactions^ which has continued ever since.

In 1642 was born the greatest scientist qf all time, Isaac
Newton. It ^vas expected that Newton would follow the
farmer's life that had been led by his ancestors, but, w^hen
he was sixteen, he showed such incompetence as a farmer that
he was sent back to school and thence to Cambridge. In 1665
the plague drove him from Cambridge, and in his mother's
farmhouse the young man worked out his discoveries of the
binomial theorem, the mathematics of infinite series, the dif-
ferential and integral calculus, the idea of universal gravita-
tion, the production of the spectrum by dispersion, and the
formulation of the laws of mechanics, following the work of
Galileo. In order to understand Newton's life, we must
realize the difference between the attitude of the men of the
seventeenth century toward their scientific work and that of
the professional scientists of today. The founders of the
Royal Society were, as has already been said, amateurs. They
were experimenting and speculating in natural philosophy
for their own interest. They considered their conclusions
and their discoveries to be their own property, -^vith which
they could do as they pleased. As Sir James Jeans says, "We
see Newton's terrifically powerful mind playing with the
problems of science as we play ^vith a crossword puzzle and
regard the incident as finished when ^\e have solved it." *

Newton discovered the calculus in 1665, yet, before pub-
lishing it even partially, he allo^ved t^venty-eight years to
elapse, years in which Gottfried von Leibniz discovered and
published the same thing in Germany. At the same time,
he satisfied himself that the force of gravity, obeying an in-
verse square law, explained the motion of the moon "pretty
nearly" and w^as content to leave it at that until Halley asked
him many years afterward what were the orbits of the planets.

* Sir James Jeans, "Newton and the Science of Today," Nature, 150,
712 (1942).

THE DEVELOPMENT OF THE SCIENTIFIC METHOD 85

In reply, Newton casually remarked that he had solved the
problem five years previously but had mislaid the proof. But
for Halley's coaxing and insistence, Newton's great work
would probably never have been published as a whole, and
it owed its publication largely to a quarrel with Hooke and
the sequel to that quarrel. The story of this extraordinary
man in relation to the science of his age is discussed in an
interesting series of papers published in Nature in 1942 to
celebrate the tercentenary of his birth.

The Royal Society was not the first scientific society. That
honor belongs to Italy, w^here the Accademia del Cimento (the
Experimental Society) was organized in Florence in 1657. It
was not an association of independent workers; it was formed
by the Medici brothers— the Grand Duke Ferdinand II and
Leopold of Tuscany. The Academy held its meetings at the
palace of Leopold, who defrayed all expenses and was the
active leader of the group. The members were ardent ama-
teurs in experimental work, many of them disciples of Galileo
or students of his disciples. When Leopold became a car-
dinal in 1667, the Academy was given up, but an account of
the work of its members was published, entitled "Saggi di
Naturali Esperienze Fatte Nell' Accademia del Cimento."
This account contained so inuch experimental detail that it
became the laboratory manual of the period. It was trans-
lated into English in 1684, Latin in 1731, French in 1755,
and was republished in a new edition in 1780. This book
formed the beginning of experimental physics and gave Italy
the leadership in that field at the time.

The Academic des Sciences, founded in 1666, arose, like
the Royal Society, from the meetings of a group of enthusi-
astic amateurs. Jean Baptiste Colbert, the great minister of
Louis XIV, obtained for it the patronage of that monarch
and the support of the French treasury. Colbert believed
firmly in a strongly centralized government, a policy that
was to some extent responsible for the misgovernment that
eventually led to the French Revolution. The Academic
was organized as a co-operative laboratory for scientific re-

86 THE PATH OF SCIENCE

search rather than as a free association of scientific workers.
The results of this co-operative work were of some value but,
as a whole, the method proved a failure, and the most im-
portant discoveries were made by individuals. The most
distinguished physicist, Huygens, was so dissatisfied that he
withdrew.

In comparing the Academic with the Royal Society, we
must remember that it had no member whose influence could
rival Newton's, for which reason its work was of the greatest
value toward the end of the eighteenth century, whereas the
Royal Society had become world-famous a century earlier.
The Berlin Academy was founded by Gottfried Wilhelm von
Leibniz, whose life span was approximately contemporaneous
with Newton's. Leibniz was, above all, a mathematician.
His work covered the whole field of physics, however, and,
in addition, he was determined to effect a reform of the edu-
cational system, especially that of the universities. He be-
lieved in the teaching of science and of "modern" subjects
such as history, geography, and mathematics, and was strongly
opposed to the emphasis placed on Latin, which acted as a
barrier to the extension of education to the people. Leibniz
made a series of proposals for the organization of a scientific
society in Germany and finally seized an opportunity created
by the formation of a commission to adopt the Catholic cal-
endar. Leibniz proposed that the Elector of Brandenburg
(the ruler of Prussia) should keep the monopoly of calendars
and use the receipts to establish a learned society and an
observatory. In 1700 the charter of the Berlin Academy was
granted, with Leibniz as its president. The results, however,
were disappointing, and Leibniz continued to agitate for the
formation of other societies in Dresden, St. Petersburg, and
Vienna.

The American Philosophical Society, the oldest scientific
society in the United States, was founded by Benjamin Frank-
lin in 1743 as the successor to a small group of enthusiasts,
the "Junto," which dated from 1727. In 1769 the American
Philosophical Society and the American Society joined to

THE DEVELOPMENT OF THE SCIENTIFIC METHOD 87

form the American Philosophical Society Held at Philadel-
phia for Promoting Useful Knowledge, under which name
the society still flourishes.

The development of science in the seventeenth century
and, indeed, in much of the eighteenth, was the work of the
scientific societies rather than of the universities. These
societies assumed responsibility for the progress of science
and developed the experimental method, which found no
welcome in the universities of that period, steeped as they
were in the spirit of tradition. As Martha Ornstein says:

It was the unmistakable and magnificent achievement of
the scientific societies of the seventeenth century, not only
to put modern science on a solid foundation, but in good
time to revolutionize the ideals and methods of the uni-
versities and render them the friends and promoters of
experimental science instead of the stubborn foes they had
so lonor been.*

* Martha Ornstein, op. cit., p. 263.

Chapter V
THE GROWTH OF PHYSICAL IDEAS

The science of physics originated in the study of the move-
ments of the heavenly bodies. The apparent movements of
the sun and moon in relation to the earth and the movement
of the planets through the constellations of the stars, the an-
nual rise and fall of the altitude of the sun, were obviously
related to the seasons and, therefore, to agriculture, to seed
time and harvest, and to such phenomena as the inundation
of the Nile, upon which the existence of Egypt depended.
After the first fanciful images, the traverse of the heavens by
the sun in a boat, for instance, a very definite cosmology was
developed to account for the observed facts; and this system
became more and more complicated as the accuracy of the
observations increased. The practical requirements of en-
gineering also demanded a system of mensuration, which
involved methods of determining the volumes of spheres,
cylinders, pyramids, and the areas of conic sections. The
early methods available to the astronomers and engineers
were essentially geometrical in form, and geometry continued
as the principal mathematical discipline until the eighteenth
century, when it was largely replaced by algebra.

It was in physical science that the Alexandrian school of
philosophers approached the discovery of the method of ex-
perimental science; * and it was, again, in physical science
that Galileo initiated the scientific revolution.f Galileo's
experiments showed that the acceleration of falling bodies
is not proportional to their weight, as was believed by the
followers of Aristotle, but that light and heavy bodies fall

* Chapter IV, p. 72.
t Chapter IV, p. 78.

THE GROWTH OF PHYSICAL IDEAS 89

in the same time and, therefore, with the same acceleration.
This discovery marks the beginning of the understanding of
the laws of motion.

Another observation made by Galileo, that the time of
swing of a pendulum is constant, regardless of the extent
of the swing, and depends only upon the length of the
pendulum itself, involved inertia and the principle that
Newton embodied in his first law of motion— that a body at
rest cannot get into motion of itself and that a body in motion
tends to continue so with the same velocity unless it is acted
upon by external forces. This law led to the idea of mo-
mentum, the product of mass and velocity. Galileo was thus
able to define acceleration: "I call a motion uniformly ac-
celerated when, starting from rest, its momentum or degree
of speed increases directly as the time measured from the
beginning of motion."

Newton embodied the same principle in his second law in
the following words: "The time of rate of change of mo-
mentum in any direction equals the moving force impressed
in that direction upon the mass particle." This second law
introduces the concept of mass as opposed to weight, which
was Galileo's concept. Galileo had realized, of course, that
matter has weight, but he did not realize that it was desirable
to have a term for the quantity of matter that a body con-
tains apart from the acceleration to which it is exposed. The
weight of a body is its mass under the acceleration of gravity.
In the first paragraph of his great book on natural philosophy,
however, Newton defined mass thus: "The quantity of matter
is the measure of the same arising from its density and bulk
conjointly. ... It is this quantity that I mean hereafter
everywhere under the name of body or mass." Thus a quan-
tity of mass remains the same, and under acceleration by
other means than gravity, the force is acting upon a given
mass rather than upon a given weight since the idea of weight
involves the acceleration of gravity.

To the two fundamental laws of motion, Newton added a
third, which dealt with reaction and in some ways seems to

90 THE PATH OF SCIENCE

be even more original than the concept of mass. Newton
showed that if a given mass is attracted toward the earth with
a certain force corresponding to its weight, the earth must be
attracted toward the mass with the same force. When a gun
is fired, for example, the shot is violently accelerated forward,
but the gun is accelerated, and not too gently, backwards.
Newton said: "Reaction is always equal and opposite to
action; that is to say, the actions of two bodies upon each
other are always equal and directly opposite." If these laws
of motion had been applied only to the observation of par-
ticles upon the earth, they would have produced much less
effect upon the minds of men than was actually the case.
Newton applied them to the movements of the heavenly
bodies and to the explanation of the law^s which Kepler had
deduced from those movements.

Johannes Kepler was the successor of Tycho Brahe, the
great Danish astronomer. At Uranienborg in Denmark,
Tycho Brahe built the first modern observatory, where by
means of quadrants he observed the positions of stars and
planets. It must be remembered that this was before the
invention of the telescope, and these quadrants were the an-
cestors of the transit instruments, fixed in meridian, with
which the time of passage of an object across the meridian
can be observed. With these quadrants equipped with sights,
Brahe made the most astonishingly accurate observations of
the positions of seven hundred and seventy-seven stars.

The cosmic theory which Brahe used was a modification of
Ptolemy's theory. He did not adopt the heliocentric Coperni-
can theory because he saw that if the positions of the stars
were observed six months apart, and Copernicus were right,
the earth would have moved in its passage around the sun a
prodigious distance in those six months and the stars should
show displacement relative to each other. Brahe's observa-
tions, made with the utmost precision of which he was
capable, showed no such movement; and he concluded that
the earth must be at rest. This is one of the many cases to
be found in the history of science where an effect which really

THE GROWTH OF PHYSICAL IDEAS 91

existed was sought for but not found because the effect was
too small to be detected by the method of observation used.
With the development of powerful telescopes, making pos-
sible observations very much more accurate than Tycho
Brahe's, the effect of the movement of the earth on its orbit
can be detected in the displacement of some stars, which we
now know to be the nearer ones. The effect is known as the
parallax and is used for determining the distance of the stars.
Tycho Brahe could not be expected to have realized the enor-
mous distance of the stars in comparison even with the size
of the orbit of the earth.

After Brahe removed to Bohemia, Kepler became his as-
sistant and on his death succeeded to his position. He could
not continue the great campaign of observation to which
Brahe had devoted his life; instead, he used Brahe's astro-
nomical data to compute the orbits of the planets. He
adopted the Copernican theory, however, which by that time
had been generally accepted. According to that theory, the
orbits of the planets were circles. But when Kepler studied
the observations of the planet Mars, he soon realized that it
did not revolve about the sun in a circle and that when it
was nearest to the sun, its motion was more rapid than when
it was farther away. Then he announced that the planets
revolved about the sun in ellipses, with the sun at one of the
foci. This was his first law. Next he showed that if a line
were drawn joining a planet to the sun as the planet revolved
in its orbit, the line would sweep out equal areas in equal
times. Finally he gave his great third law, that the squares
of the periods of revolution of the planets around the sun
are proportional to the cubes of their average distances from
the sun. These laws were statements of fact that Kepler de-
rived from Brahe's observations.

When Newton took up the matter, he showed that Kepler's
third law would be true provided that there were an at-
tracting force between the sun and the planet that varied
inversely as the square of the distance and that Kepler's
second law could be explained by the same assumption. If

92 THE PATH OF SCIENCE

the sun attracted a planet by a force varying inversely as the
square of the distance, a line joining the planet to the sun
would sweep out equal areas in equal times. This assump-
tion—that there existed in the universe a force extending out-
ward to the planets and varying inversely as the square of
the distance to them— applied, of course, to all heavenly
bodies; and Newton applied it to the position of the moon
in its movement around the earth. He found, however, that
it did not agiee exactly with the observations, which involved,
of course, the diameter of the earth; and for sixteen years
Newton put the work aside. In 1682 it was discovered that
the diameter of the earth had been measured incorrectly and
was over 500 miles greater than the figure that had been
adopted.* Newton immediately repeated his calculations
and found that they agreed with the observed motion of the
moon. He then extended the work to include the motions of
the planets and their satellites, comets, and even the tides of
the sea. He stated his general law of gravitation: "Every
particle of matter in the universe attracts every other particle
with a force that varies directly as the product of the mass
and inversely as the square of the distance."

The discovery of the fundamental laws of motion was a
challenge to philosophers to seek fundamental principles that
would supply laws of a general nature. The mathematicians
d'Alembert, Euler, Lagrange, and Laplace developed such
general principles, derived from the laws of motion, which
were applicable not only to material bodies but to the flow
of light, heat, and electricity. On the mathematical prin-
ciples that they established, the science of physics has been
built. Although the physical ideas themselves have changed
with the progress of experimental science, the new ideas have
been expressed in terms of the same fundamental principles.
In the nineteenth century, physicists thought that it might
be possible to reduce all laws to the laws of mechanics.

* It is possible that Newton's difficulty arose instead from lack of
proof that the mass of a spherical body would behave as if it were
concentrated at the center.

THE GROWTH OF PHYSICAL IDEAS 93

Laplace said: "Give me the position and velocity of all the
particles at a given moment and I will predict the state of
the world at any future moment." The statistical theory of
heat, attributed to Ludwig Boltzmann, the electromagnetic
theory of light, and the "fluid" theory of electricity tended
to confirm this mechanistic viewpoint.

The nature of heat attracted little attention in ancient
times. Fire was one of Aristotle's four elements, and heat
was considered an imponderable substance, to which Antoine
Lavoisier s^ave the name caloric. That some substances
should absorb heat more readily than others ^\ as ascribed to
their greater power of attraction and was expressed as their
having greater capacity for heat.

The first scientist to study heat systematically was Joseph
Black, a chemist of Glasgow. He observed that when ice
melts, it absorbs heat without undergoing any change in
temperature; and Black named the heat which disappears
in the process latent heat. Black showed that, in the melting
of ice, heat was absorbed equivalent to that made available
by the cooling of an equal mass of water through 140° Fahren-
heit. Black also discovered that heat is used in the evapora-
tion of water. It requires, indeed, nearly seven times as much
heat to change a pound of water into steam as to melt a pound
of ice.

The discovery that heat was not a substance was made by
Benjamin Rumford and Humphry Davy, who showed by ex-
periment that heat could be produced by friction. Rumford
was engaged in the boring of cannon in the military work-
shops of Bavaria and observed the amount of heat produced
by the boring tool. He arranged one experiment in which
water was boiled by the heat generated in boring the metal.
Davy showed that ice could be melted by friction. These
experiments were made at the end of the eighteenth century.
At the beginning of the nineteenth century John Dalton ad-
vanced his atomic theory (see Chapter VI, page 121), and it
was realized that matter consisted of molecules and that its
properties might be due to the behavior of these molecules.

94 THE PATH OF SCIENCE

Thus evolved the idea that heat is a mode of motion, the
motion of the molecules; that a hot body is one in which the
molecules are moving energetically; and that the latent heat
of evaporation of water is the energy absorbed in giving
rapid motion to the molecules leaving the liquid surface.

As a result of the work of Nicolas Carnot on the theory
of the steam engine and of Julius Mayer and James Joule
on the transformation of mechanical work into heat, the law
of the conservation of energy was enunciated, often known
as the first law of thermodynamics: "Energy can neither be
created nor destroyed, but it may be changed from one form
to another."

This principle, simple as it seems, has been one of the chief
guiding principles of physics ever since it was first stated.
Motion, heat, light, and electricity— all are forms of energy,
and they can be transformed into each other. Indeed, the
science of physics deals primarily with this transformation.
With the discovery by Einstein that mass and energy also
are interchangeable, that the motion of a particle involves
a change in its mass— a change that becomes great only when
its velocity approaches that of light— and, still more impor-
tant, that the destruction of mass liberates enormous quan-
tities of energy, the understanding of the transformations of
energy became a knowledge of the physical laws of the uni-
verse. The great principle that governs transformation of
energy is the second law of thermodynamics: In those trans-
formations, energy loses potential. Heat, for instance, can-
not of itself pass from a colder to a warmer body. Mechani-
cal effect cannot be derived by cooling matter below the
temperature of the coldest surrounding objects. The tend-
ency of energy transformations is to diminish the difference
in energy levels. The quantity of energy transferred, divided
by the temperature, is called the entropy. And the second
law of thermodynamics can be stated in the terms that the
entropy of any closed system tends to increase. In mechanics
and electricity the potential always decreases if no outside
energy is added. A transformation in which the entropy

THE GROWTH OF PHYSICAL IDEAS 95

remains constant is reversible, whereas one in which the
entropy increases must be irreversible. In dealing with the
transformation of energy, therefore, physicists use two vari-
ables: the energy involved and the entropy of the system.
In any transformation of energy for which ^ve wish to write
the equations, the first law of thermodynamics states that the
energy must remain constant after the transformation; that
is, the two sides of the equation must balance. The second
law of thermodynamics states that the entropy must increase
in carrying out the transformation.

The attempt to reduce all laws to mechanical laws led to
the statistical theory of heat, formulated by Boltzmann and
very successfully applied to chemical problems by W^illard
Gibbs. The investigation of the states of matter (gaseous,
liquid, solid) and especially of its behavior at very low tem-
peratures (near the absolute zero) forms the basis of much
research in the field of thermodynamics.

In the earliest speculations on the nature of light, Plato
and Aristotle held that light is derived from the eye, and
they pictured the eye as sending out something that inter-
cepted an object and so illuminated it. This idea, however,
was supplanted by the idea that the light was emitted from
the object seen; and much later it was realized that light is
emitted by such light sources as the sun and reflected to the
eye by objects seen.

Lenses were known to the ancients. The use that was
made of them is not known. Possibly the crystal lenses that
have been found were considered to be merely ornamental,
although the fact that they would concentrate the rays from
the sun and would act as burning glasses is mentioned by
Aristophanes. In medieval times lenses were certainly used
as magnifying glasses to assist in reading. It is not a very
long step from the use of a lens in the hand to the produc-
tion of lenses in a mount that can be carried on the face and
thus to the invention of spectacles; but the invention of
spectacles must have been a most important step in increas-
ing the efficiency of those suffering from the small defects

96 THE PATH OF SCIENCE

of vision that are so common. Spectacles came into use in
Italy about the end of the thirteenth century, and it is hard
to believe that nothing else of importance was done with
lenses until two were combined to form a telescope, nearly
three hundred years later.

The first attempt to discuss the theory of lenses was made
by Kepler, who wrote a book on the theory of the telescope.
This was just after the publication of the work of Galileo
and the discoveries he had made with the instrument. It is
interesting that the effect of the revolutionary discovery of
the telescope on Kepler was to incite him to a discussion of
its theory. One can imagine how different would have been
the course of events if Tycho Brahe had lived to learn of the
existence of the telescope. The results of Kepler's calcula-
tions varied little from the observed facts, but he did not
know the law of refraction; that is, the way in which a ray
of light is deviated when it passes from air to glass. In spite
of this, Kepler's work was undoubtedly very valuable in pro-
viding a basis for the design of refracting telescopes.

The correct statement of the law of refraction was given
by Willebrord Snell at the University of Leyden in 1621, but
his manuscript was not published at the time; and the law
was embodied by Descartes, the great philosopher and mathe-
matician, in his book on optics. Descartes, however, prefaced
the statement of Snell's law with a mechanical theory of the
nature of light, in which he assumed that light traveled more
rapidly in denser media. Pierre de Fermat, the French
mathematician who formulated the theory of numbers, de-
duced the law of refraction from exactly the opposite as-
sumption, namely, that light travels more slowly in denser
media, and announced the great principle known ever since
by his name— that a ray of light originating at a point in one
medium will travel to a point in another medium by the
path which requires the minimum of time. Of all principles
in optics, this has been perhaps the most fruitful.

As in mechanics, the great scientist who advanced the
whole theory of optics was Isaac Newton. Newton showed

THE GROWTH OF PHYSICAL IDEAS 97

experimentally that a prism splits a ray of light refracted
through it into a band of colors. White light could there-
fore be considered to contain rays of various degrees of re-
frangibility, the least refrangible rays being red and the most
refrangible, violet. Thus Newton discovered the spectrum
and with it much relating to the nature of color. Newton
made another observation which later became of the utmost
importance, namely, that when a thin film of air occurs be-
tween two plates of glass, the film shows colors, and these
colors depend upon the thickness of the film.

The distinction between the physical and the psychological
properties of color was first made clear at the beginning of
the nineteenth century by Thomas Young, who advanced a
theory of color vision according to which the eye perceives
three fundamental sensations— red, green, and violet— and all
other color sensations arise from combinations of these three.
Yellow, for instance, arises from simultaneous sensations of
red and green. The distinction between the psychological
basis of color and its physical basis in the differing refrangi-
bility of the rays of light has been a difficulty for scientific
workers and artists ever since the days of Newton. The pig-
ments of the artists have as their fundamental colors the com-
piementaries to Young's sensation primaries, and only with
the advance of color photography in recent years have the
relations between the sensation primaries and the pigment
colors become familiar to the general public.

As a result of his work on the refraction of light through
prisms, Newton inferred that the dispersion of a prism is
always proportional to the deviation it produces; that is, he
didn't realize that by the use of glass of different kinds prisms
could be made that for a given refraction would give different
deviations between the rays of varying colors. Newton con-
cluded that it was not possible to correct the variation in the
focal length of a lens for different colors, an effect which is
generally known as the chromatic aberration of the lens. He
abandoned the idea of making telescopes of great power by

98 THE PATH OF SCIENCE

means of lenses and invented reflecting telescopes, using mir-
rors to avoid the difficulty with chromatic aberration.

It was shown experimentally about the middle of the
eighteenth century that Newton had been wrong and that
achromatic lenses could be made. The whole subject was put
on a solid foundation by Fraunhofer, who in 1817 discovered
that in the solar spectrum there were certain dark lines that
enabled him to identify the positions of the colors of the
spectrum with accuracy and to measure with precision the
refractive indices of glass for light of different colors.

Joseph von Fraunhofer was able to calculate the principles
required for the achromatism of the telescope and made an
excellent refractor of 9%-inch aperture to be used by the
astronomers of Dorpat Observatory. Fraunhofer also made
optical glass and was really the first working optical instru-
ment maker of the modern school.

While the use of light in optical instruments w^as advanc-
ing, the nature of light continued to engage the minds of
men. Newton had devoted much thought to the dynamics
of particles, and it is not surprising that he considered light
to consist of material particles emitted from heated bodies
and producing a mechanical effect by their action on the eye.
A phenomenon observed by Francesco Grimaldi, however,
was difficult to reconcile with any theory that considered light
to consist of particles, that is, that if a point source of light
illuminates a sharp straight edge, such as a knife blade, the
shadow will be bounded by a series of light and dark bands.
To this phenomenon Grimaldi gave the very appropriate
name of diffraction^ by which it is still known. Diffraction
had also been observed by Robert Hooke, the energetic and
versatile secretary of the Royal Society, who concluded that
there was some kind of vibrating motion in light. Thus
Newton was induced to suggest that the corpuscles of light
embodied a vibratory element. The rays of light, for in-
stance, in passing by the edges of bodies might be bent back-
wards and forwards several times "with a motion like that of
an eel."

THE GROWTH OF PHYSICAL IDEAS 99

Another observation of the greatest importance in under-
standing the nature of light was the discovery, as a result of
observations of the eclipses of the satellites of Jupiter by the
body of the planet, that light did not travel with infinite
speed. Indeed, in 1676 Olaus Romer calculated from these
observations that the velocity of light was about one hun-
dred and ninety thousand miles a second, a value little dif-
ferent from the value used today.

The great opponent of Newton's theory of the emission of
light as particles was Christiaan Huygens, the Dutch astrono-
mer who first made accurate clocks by the use of the pendu-
lum and discovered the double refraction of Iceland spar and
the refraction of the light of the stars by the atmosphere.
Huygens regarded light as being non-material because of its
great velocity of propagation and because two rays traversing
the same path in contrary directions do not hinder each other.
He therefore adopted the theory that light consists of wave
motions in a hypothetical medium that is called the ether.
The properties of the ether are deduced from the properties
of light. Huygens considered each point of a luminous body
to be the origin of elementary spherical waves, of which the
envelope corresponds at any instant to the position of the
wave front. Thus, as the wave front travels forward ^vith
the velocity of light, it could always be considered as the
envelope of an infinite number of elementary waves. The
perpendicular to the wave front corresponds to what is termed
a ray.

Newton's corpuscular theory and Huygens' wave theory
are equally adapted to describe the phenomena of reflection
and refraction. The literature of the eighteenth century is
full of discussion of the two theories, but in 1827 W. B. Ham-
ilton proved that they are only different aspects of the same
mathematical laws which can be derived from de Fermat's
principle. The wave surfaces can be considered as the poten-
tial surfaces of the light rays, and the light rays as the normals
of the wave surfaces. None of these theories alone, however,
can explain the phenomena of diffraction and interference.

100 THE PATH OF SCIENCE

They involve a periodic disturbance moving along the rays
from wave surface to wave surface. Two rays or two waves
coming from the same point source can be united in a point
in such a way that the maximum of one wave ^vill coincide
with the minimum of the other and so neutralize it. Thus
two waves of light can, under certain circuinstances, produce
darkness. This idea was given definite form in 1801 by
Thomas Young. Before this, the corpuscular theory of light
had been generally accepted for almost a century, largely be-
cause it had been sponsored by Isaac Newton. Young
founded his views on the nature of light on the following
hypotheses:

A luminous body produces ^vaves in a medium, the ether,
w^hich pervades the entire universe. Different colors of light
owe their differences to the frequency of their vibrations,
which produce different sensations in the retina. The pro-
duction of darkness by the mutual action of two waves of
light Young described as interference; and he was able to
measure and explain by the wave theory both the diffraction
fringes discovered by Grimaldi and the colors of thin films
discovered by Newton. Young measured the length of the
waves of light, finding that the limit of the spectrum in the
red corresponded to waves about 0.0007 millimeter long,
while the violet rays at the other end of the spectrum had a
length of 0.0004 millimeter.

Young's theory was improved by Augustin Fresnel, who
considered that the waves moving along the rays ^vere trans-
verse waves, vibrations in the plane perpendicular to the
path of the light. This made it possible to explain not only
diffraction and interference but also the phenomenon of
polarization, which had been discovered in 1809 by E. L.
Malus, a French physicist, who had observed that light re-
flected by a mirror at an incidence angle of about 57° is
totally polarized, that is, it has vibrations only in the direc-
tion normal to the ray in the plane of reflection. A second
reflection from a plane at right angles to the first will extin-
guish the light. Malus had then directed his attention to the

THE GROWTH OF PHYSICAL IDEAS, TOr

double refraction of Iceland spar and had found tFiat both
rays are polarized, the planes of polarization being at right
angles to each other. Fresnel's theory explained both inter-
ference and polarization and gave the mathematical relations
for all these phenomena. Fresnel thought of the vibrations
of light as vibrations of the ether, which now assumed con-
tradictory qualities because the great velocity of light made
necessary the idea that the ether was a solid of enormous
rigidity, while at the same tiine it imposed no resistance to
the passage of matter such as the planets.

Much of the theoretical work of the nineteenth century
was concerned with the discussion of the properties of the
ether and its relation to matter, but the gi^eatest advance in
the whole theory of radiation came with the suggestion in
1864 by J. Clark Maxwell that light w^as an electromagnetic
phenomenon. Maxwell investigated mathematically the
propagation of electric and magnetic forces in space and
found the velocity of propagation to be identical with the
known velocity of light and the calculated properties— those-
actually exhibited by light. He showed that in electromag--
netic waves the electric and magnetic vibrations occur at right,
angles to each other and to the direction of the ray, ^vhich is,,
of course, normal to the waves of light, and that electromag-.
netic waves would be capable of being polarized and w;ould
show the phenomena of refraction, reflection, and interfer-
ence. Thus he considered light an electromagnetic phenome-
non corresponding to a restricted range of wave lengths; and
he concluded that longer waves might exist which were far
too long to be seen by the eye but could conceivably be
detected by other means.

This theory was confirmed experimentally by Heinrich
Hertz in 1887, and the electric waves discovered by him are
those now used in radio communication. The w^hole range
of electromagnetic radiation between the radio waves, many
meters long, and the waves of light has been generated and
observed. Moreover, the discovery of waves shorter than
those of visible light, known as ultraviolet waves , was fok

Tl02 THE PATH OF SCIENCE

lowed by the detection of waves too short to pass through the
air and then by the proof that the x-rays (page 106) are very
short eleGtromagnetic waves of the same nature as light waves.
As we shall see later, the most recent work on the nature of
,electrornag;Hetic waves has brought us back to the conception
that all wayes are associated with particles and that the long
.controy-ersy between the wave theory and the corpuscular
•theory .can ;b;e j.esolved to some extent in a compromise.

Only t-^y<9 manifestations of the properties of electricity
were knawn ^p the ancients. They knew that magnetite ore
would attract aBcJ be attracted by iron and that amber when
rubbed would attract light particles, straw, paper, etc. In the
Middle Age^ it wa^:? found that a suspended piece of magnetite
would poi^t i0.c)ir!tji :and south, and the mariner's compass was
invented. At;the time when Galileo was working in Florence,
an English physician, William Gilbert, was carrying out ex-
periments on the magtiet and the attracting properties of sub-
stances ys^hic^h Ji:^d J^^n rubbed, and he showed that the be-
havior of the ,camTp^a<ss was due to the fact that the earth itself
was a great magnet. Gilbert also found that other substances
than amber=--glass^ ^stiifur, and resin— ^vould attract light par-
ticles after they had been rubbed. He wrote the first text-
book on electric-al ^scieriee, in which he discussed his experi-
ments.

At the beginning of the eighteenth century, Stephen Gray
found that an electric charge, the existence of which ^vas
known by its capacity for attracting particles, could move
along a thread, ^ind he even transferred such a charge along
a hemp thread a thousand feet long suspended by threads of
silk placed at intervals. Then, ^vhen the thread was sus-
pended by metal wires, the charge vanished, being conducted
away by the wires. In 1729 Gray discovered that an electri-
fied glass tube would induce a charge in another tube close
by but not touching it, and a number of experimenters con-
tinued to study the nature of isolated electric charges and the
properties of static electricity. Electric machines for pro-
,ducing powerful charge^ by means of induction were de-

THE GROWTH OF PHYSICAL IDEAS 103

signed, and the Leyden jar was invented, in which two con-
ducting layers were separated by the glass of the jar, so that
opposite charges could be stored on the t^vo faces of the glass.
Interest in static electricity was greatly stimulated by the spec-
tacular results obtained. Benjamin Franklin discovered that
the charges in the jar reside on the glass walls, and he built
a condenser using a series of glass plates separated by sheets
of tin foil, thus obtaining the condenser which we use today.

All this work dealt wdth static electricity, and it \\as not
until the close of the eighteenth century that electricity in
motion was investigated. Luigi Galvani, an Italian anato-
mist, observed that under the stimulation of an electric
charge a frog's legs isolated from the body would show con-
traction and that it could be produced by the simple contact
of two different metals moistened by the salty juices of a
frog's body. Galvani, in fact, discovered the possibility of
producing an electric current, for which the frog's leg was
the detector. This discovery was followed up by Alessandro
Volta, who in 1800 announced his voltaic pile, which con-
sisted of a series of alternate copper and zinc plates sepa-
rated by pieces of paper or flannel moistened with brine.
This was the first battery, and experimenters soon designed
improved batteries and were able to get electric currents with
which chemical effects could be produced. Water was de-
composed into hydrogen and oxygen, and Davy, experiment-
ing at the Royal Institution, decomposed potash wdth a bat-
tery of two hundred and fifty cells and obtained the metal
potassium. Later he prepared sodium, calcium, barium,
strontium, and magnesium. With two thousand cells, he
produced the first arc lamp and in the arc melted refractory
substances such as platinum and quartz.

In 1819, Hans Oersted of the University of Copenhagen
made a discovery which is the foundation of the science of
electromagnetism. He found that a wire carrying a current
would displace a compass needle w^hen it was parallel to it
and thus demonstrated that a conductor bearing an electric
current produces a magnetic field. Oersted's experiments

104 THE PATH OF SCIENCE

were immediately follo^ved by those of a great Frenchman,
Andre Ampere, who wdthin a few months of Oersted's an-
nouncement found tliat two parallel electric currents would
behave like magnets, attracting and repelling each other,
according to the direction in which they flow^ed. In 1823
Ampere published a paper setting forth the mathematical
theory of the effects of electromagnetism.

The inverse effect to Oersted's w^as not discovered for some
years. It was in 1831 that Michael Faraday found that the
movement of an electric circuit in a magnetic field caused a
current to start in the circuit, so that just as Oersted had
shown that a current produced a magnetic field, Faraday
showed that a magnetic field would produce a current. As
a result of this discovery, it became possible to generate elec-
tricity mechanically by the rotation of coils of wire in the
field of a magnet. This is the arrangement known as the
dynamo; and the inverse arrangement, in which the passage
of electricity through a coil in a magnetic field causes it to
rotate, is the electric motor. Thus, by the middle of the
nineteenth century, from the work of Ampere, Michael Fara-
day, and Joseph Henry in the United States, the general na-
ture of current electricity and especially the properties of
circuits carrying direct current were completely unraveled.
The development of alternating-current electricity belongs
to the field of engineering rather than of physics. It is the
work of the electrical engineers in the second half of the
nineteenth century that made possible the great use of elec-
tricity in practical applications. Electric light, the telegraph,
the telephone, and so forth represent applications of early
discoveries relating to electric currents by a large group of
scientists and an even greater group of engineers.

The nature of electricity itself long remained completely
hidden. Its elucidation came not from further work in rela-
tion to electricity itself, but from the study of the conduction
of electricity through gases. As early as 1785, William
Morgan in a paper before the Royal Society referred to the
glow that could be obtained when electricity was passed

THE GROWTH OF PHYSICAL IDEAS 105

through an evacuated glass vessel. But the earliest systematic
research on the subject was that of Faraday, ^vho in 1836
began to study the passage of electricity through gases. He
observed that if t^vo electrodes were sealed into a bulb that
was then evacuated, and electricity ^vas passed through it from
a frictional electricity machine, there appeared Tvhat he de-
scribed as a "light" proceeding from the negative electrode.
Faraday was limited both in the supply of electricity from
his frictional machine and in the vacuum that he could ob-
tain by the use of a piston pump.

Improved methods of obtaining high vacuum by filling
the bulbs with carbon dioxide and then absorbing^ it Tvdth
caustic potash made possible greater experimental progress.
J. Gassiot in 1859 described experiments in which he un-
doubtedly obtained the beam that became knoAvn as a cathode
ray. The passage of electricity through exhausted tubes con-
taining a small amount of gas became very popular as a dem-
onstration, and Heinrich Geissler, a German glass blower,
became so skillful in the preparation of the tubes that they
are known as Geissler tubes.

Another technical development was the introduction by
Ruhmkorff in Paris of the induction coil, which facilitated
the production of high electrical voltages. In 1869 J. ^V^
Hittorf published a first communication on electrical con-
ductivity in gases. This work was concerned ^vith ^vhat he
calls the negative discharge^ now called the cathode rays. He
pictured it as thin, flexible filaments, carrying currents,
that could be deviated by a magnetic field and that, by a
suitable arrangement of the field, could be focused, and he
observed an intense heating at the focus. Hittorf also dis-
covered the use of the incandescent cathode, with which a
current could be maintained through the tube with a very
small voltage.

Hittorf's experiments were repeated by "VV^illiam Crookes,
who carried out a very large number of observations on elec-
trical charges and exhausted tubes. Crookes showed that the
cathode rays had sufficient momentum to drive a small paddle

106 THE PATH OF SCIENCE

wheel of light metal built inside the tube, which led to his
conclusion that the cathode rays consisted of small particles.
Like Hittorf, he found that the rays could be deviated by a
magnet, and as a consequence they must consist of charged
particles. When they fell on an extra electrode inserted in
the tube, they charged it negatively. Moreover, their velocity
could be determined and was found to be very high, in some
cases approaching the velocity of light. Crookes suggested
that the cathode rays consisted of a new form of matter.

In 1892 H. Hertz, who had discovered the long wave elec-
tromagnetic waves, which are used in radio work, published a
paper in which he showed that cathode rays can pass through
thin metal foils. Two years later, P. Lenard made a tube
containing a thin aluminum window, through which the
cathode rays could escape into the air. At that time Wilhelm
Roentgen was professor of physics at the University of Wurz-
burg. He covered an ordinary Hittorf vacuum tube with
black paper, probably to see whether Lenard's rays could
escape into the open from an ordinary glass tube. He noticed
that barium platinocyanide crystals glowed by fluorescence in
the dark room, although there was black paper between the
tube and the crystals, and realized that some rays from the
tube must penetrate the black paper. Then he found that
these rays would affect a photographic plate, would pass
through matter generally, and so enable the structure of
things to be photographed as shadows. This work was the
very important discovery of the x-rays. It had been missed
by many earlier experimenters. Perhaps Morgan had ac-
tually produced x-rays in his experiments a hundred years
before Roentgen recognized them. Hittorf and Crookes cer-
tainly must have produced x-rays hundreds of times, and
Crookes actually fogged a box of photographic plates in his
laboratory. It was only when he heard of Roentgen's dis-
covery many years later that he understood that his plates
had been fogged by the x-rays produced from his own vacuum
tubes.

THE GROWTH OF PHYSICAL IDEAS 107

When Thomson showed later that the cathode stream irt
an exhausted tube is a stream of electrons, it was realized that
electrons falling on a target, such as the end of the tube, cause
x-rays to be emitted, and targets were then placed in the tubes
so that the cathode stream was focused on them. The early
x-ray tubes had a hemispherical cathode and a target or anti-
cathode, as it was called, made of platinum. These tubeS'
were exhausted to a high vacuum, but not too high, as other-^
wise the current would not pass.

In 1884 J. J. Thomson became the Cavendish professof of
physics at the University of Cambridge, and as his first major
piece of work he started to study the cathode rays to deter*
mine whether they were of a wave nature, similar to light,
or whether, as Crookes believed, they consisted of particles
carrying a charge of electricity. Thomson wrote many years
afterward: *

I had for a long time been convinced that these rays
were charged particles, but it was some time before I had
any suspicion that they were anything but charged atoms.
My first doubts as to this being the case arose when I meas-
ured the deflection of the rays by a magnet, for this was far
greater than I could account for by any hypothesis which
seemed at all reasonable if the particles had a mass at all
approaching that of the hydrogen atom, the smallest then
known.

By measuring both the magnetic deviation and the total
energy of the rays, using a thermocouple to find their heat-
ing effect, Thomson was able to calculate the velocity of the
rays and the ratio of the mass of the particles to the electric
charge. The conclusion showed that the velocity was enor-
mously high— 5 per cent of the velocity of light, much higher
than could be expected for any molecule or atom— and that
the ratio of the mass to the charge was much less than would
be possible for hydrogen atoms. If the rays consisted of elec-
trified particles, the particles were something quite new to

* Lord Rayleigh, Sir J. J. Thomson, p. 80, Cambridge University
Press, 1942.

108 THE PATH OF SCIENCE

science. That they were due to particles was shown by the
fact that they could be deviated by a transverse electrostatic
field. Tests on this subject had failed previously because the
gas pressure in the tube was too high. In 1897, then, Thom-
son finally showed that the cathode rays consist of charged
particles and that these particles are very small— about one
two-thousandth of the inass of the hydrogen atom. The name
electron had already been given to the atom of negative elec-
tricity by Johnstone Stoney in 1874, at the time that he put
forward his idea of atomistic electricity. It was now realized
that the particles of the cathode rays are electrons.

Another application of this inethod of using electro-mag-
netic and electrostatic fields to control a stream of elec-
tricity in a vacuum ^vas applied to the positively charged
streams that come from the anode. These positive rays can
be deviated by a magnetic field and also by an electrical field,
but the amount of the deviation is much less than that of the
cathode rays because the particles froin the anode are much
heavier than those from the cathode. They can be shown to
consist of streams of atoms or inolecules. Moreover, such a
stream contains a number of different atoms, and since these
are of different mass, they will be separated by the magnetic
field. This work was done by Thomson and his student
F. W. Aston. Later, Aston designed an instrument which
he called the mass spectrograph^, in which the positive ray
passed through a magnetic field so that the atoms of differ-
ent mass were separated, the streams of different atoms being
detected either by their record on a photographic film or by
the measurement of the ionizing po^ver of the stream when
allowed to run into a chamber containing gas of ^vhich the
conductivity could be measured. A very important result of
Aston's work was the discovery that frequently several atoms
of the same element exist having different masses. Thus, in
the case of neon, one of the first elements to be investigated,
about 90 per cent of the gas consists of atoms having a inass
of 20, whereas 10 per cent consists of atoms having a mass
of 22 units. Atoms having the same chemical properties but

THE GROWTH OF PHYSICAL IDEAS 109

different masses are known as isotopic elements. As a result
of Thomson's work, the general nature of electricity became
clear, and it was realized that a current of electricity was a
current of electrons, which are the atoms of electricity in the
sense that they are the smallest unit of electricity known.
Each electron carries its unit charge, while its mass is approxi-
mately one two-thousandth of that of the atom of hydrogen.

The elucidation of the nature of electricity had two results
of the utmost importance. It made possible a new field of
electrical engineering, ^vhich has become generally known as
electronics. It also made possible the understanding of the
structure of the chemical atoms and of the nature of radio-
activity, and this we shall deal with later.

The engineering applications of electronics depend upon
the use of streams of electrons to control electric circuits.
The first observation which led to this was made by Edison,
who observed that when he sealed two elements into a lamp
and heated one of them by a current, the second filament in
the vacuum received electricity across the space from the
heated filament. This was before the work of Thomson, but
we now see that what Edison observed was the passage of
electrons across the vacuum from the heated filament to the
cold one. Edison did not follow up the observation, but it
was studied by others, notably by J. A. Fleming and by Lee de
Forest, who had the idea of introducing into the space be-
tween the two filaments a grid of wires, by charging which
he could control the flow of electrons across the space.

The electronic tubes, now so widely used, are essentially
valves which control the flow of electric current through a
circuit as a valve controls the flow of water through a pipe.
When a valve tube is put into an electric circuit, the circuit
is broken because, in the tube, there is an open space across
which the electrons must pass in order to maintain the flow
of current through the circuit. At this point the current can
be controlled. For example, if an alternating current is ap-
plied to the tube, the anode at w^hich the electrons are re-
cei\ed becomes alternately positively and negatively charged.

no THE PATH OF SCIENCE

When it is positively charged, the anode will attract the
electrons, and the current will flo^w W^hen it is negatively
cliarged, it will repel the electrons and no current will flow,
so that an alternating current applied to a valve tube will be
transformed into a pulsating current in one direction, the
pulsations in the opposite direction being suppressed by the
tube. Then if a grid is inserted in the tube, the flow of the
electrons can be controlled by the charge on the giid. If a
signal current is applied to the grid, the flo^v of electrons
through the tube will follow the signal current, and in this
way a small signal current can be enormously amplified by
means of a tube.

In the so-called photo tubes, electrons are emitted when
light falls on the cathode, and thus a beam of light can con-
trol an electric current which will follow the variations in
the light. By means of a photo tube, we can transform light
signals into electric signals and then by means of amplifying
tubes increase the electric currents so that they can perform
all sorts of operations. In this way, the reproduction of
sound can be accomplished. The sound waves can be used
in a microphone to control an electric current that can make
a lamp glow, and the variation of the intensity of the light
will therefore correspond to the sound. This variation can
be recorded photographically on a film. Light passing
through the record can be used to produce a current in a
photo tube, and this current can be amplified to operate a
loud speaker, by which the sound can be reproduced.

W. D. Coolidge, working in the research laboratory of the
General Electric Company, improved the x-ray tube very
much by using a hot cathode, from which electrons ^vere
emitted even in a vacuum too high for the passage of elec-
tricity from a cold cathode, and by using a heavy tungsten
target that could withstand the powerful beam instead of the
thin platinum target used previously. At the same time, the
machines used to generate the electricity were gixatly im-
proved, and in this way x-ray sources of great intensity were
made available.

THE GROWTH OF PHYSICAL IDEAS 111

The nature of the x-rays was a subject of discussion for
many years after tlieir discovery. It seemed equally probable
that the x-rays consisted of streams of particles having some
analogy to the cathode rays and that they might be waves
similar to light waves. The x-rays could not be refracted, as
light is, by dense media, and for a time all attempts to diffract
them failed. Finally, Max von Laue, the director of the In-
stitute of Theoretical Physics in Berlin, showed that a dif-
fraction pattern could be produced from a beam of x-rays by
the use of a natural crystal. It was generally agreed that
x-rays represented an electromagnetic radiation similar to
that of light but of much shorter wave length, the x-rays from
a tungsten target having a wave length about one five-
thousandth that of visible light.

The discovery of the x-rays was follow^ed by the discovery
of radioactivity and the identification of the alpha particles
emitted by radium with doubly charged helium atoms by Sir
Ernest Rutherford.* This work on radioactivity focused
Rutherford's attention on the structure of the atom, and in
1913 he suggested that atoms were made up of a nucleus con-
taining practically the whole of the mass of the atom and a
number of electrons rotating in orbits around the central
nucleus which were sufficient to neutralize the charge on the
nucleus and thus insure an electrically neutral atom. Ruther-
ford was led to this view of the structure of the atom by ex-
periments on the deviation of rays, particularly the alpha
rays, when they collided with atoms, just as something could
be learned about the shape of a building by the way in which
balls thrown at it bounced.

At the same time, Niels Bohr w^as studying another prop-
erty of atoms, the spectra ^vhich they emit when they are
excited by the passage of electricity. When atoms are excited
electrically, as gases in a vacuum tube or an electric arc for
instance, they emit spectra w^hich are not continuous, like
those of hot bodies, but consist of isolated lines. Some of

* Chapter VI, p. 136.

112 THE PATH OF SCIENCE

these spectra are very complex. The wave length of the lines
emitted can be measured, and certain numerical relationships
between them had been deduced as the result of a long study
of the problem by many workers. A mechanism for the
emission of a spectrum by a given element was still lacking
when Bohr took up the problem. In 1913 he suggested that
the action in the atom that resulted in the emission of a
spectral line was the movement of one of the rotating elec-
trons from one orbit to another. Taking Rutherford's pic-
ture of the atom, in which the electrons rotate around a
nucleus, Bohr assumed that as long as the electron rotated
in a given orbit, it would not radiate any energy; but that
if it changed its orbit and shifted to a smaller one, energy
would be set free and would be emitted as a spectral line.
Moreover, the orbits of the electrons would be at discrete
definite distances from the nucleus. The radii of these orbits
would, in fact, be proportional to the squares of successive
whole numbers— 1, 4, 9, 16, etc. Consequently, whenever an
electron shifts from one orbit to another, it emits energy of
a definite amount, which corresponds, of course, to a definite
wave length in the light emitted.

The idea that energy was emitted by atoms in definitely
fixed amounts, corresponding to the change in diameter of
the electron orbits, supplied a mechanism for a general law
of radiation that had been announced by Max Planck about
ten years before— that radiation is emitted in definite units,
so to speak, atoms of energy, ^vhich Planck named quanta.
Bohr, using Rutherford's idea of the atom, supplied a
mechanism for Planck's quantum theory of radiation. The
structure of the Bohr-Rutherford atom has undergone some
modification since it was originally suggested. It has become
established, however, as a basic principle and has been able
to explain a great many different phenomena, such as the
radiation of hot bodies, the emission of spectra, the absorp-
tion spectra of molecules, the chemical structure of com-
pounds, the effect upon atoms of radiation, and the radio
active elements and their behavior.

THE GROWTH OF PHYSICAL IDEAS 113

Planck's atomic theory of the structure of energy led to a
revival of the old argument as to whether radiation was in
the form of waves or of streams of particles. According to
Planck, radiation was in quanta, each of which had an energy
content of Jjv, where h is a universal constant and v is the
frequency, that is, the inverse of the wave length, of the radi-
ation. This involved a discussion of the physical structure of
these quanta— whether they consisted, for instance, of short
trains of ^vaves, since the wave structure was implicit in the
definition of frequency. Another form of radiation is that of
the cathode ray; it is known to consist of streams of electrons.

Louis V. de Broglie, a gifted French amateur who has de-
voted his life to research in physics, suggested that if the
structure of radiant energy, which is associated with ^vave
length, had an atomic and discontinuous nature, then matter,
which obviously is atomic and discontinuous, inight also have
properties associated wdth waves. This was confirmed by the
experiments of C. J. Davisson and L. H. Germer in the Bell
Telephone Research Laboratory. They succeeded in dif-
fracting electron beams, w^ork which has been followed by the
development of the electron microscope, in which a beam of
electrons forms images parallel to those formed by light in
a microscope. The t^vo aspects of radiation were finally
reconciled by the work of W. Heisenberg and of Erwin
Schroedinger, who took up the old ideas of Hamilton with
regard to the dualistic aspect of rays and waves and initiated
the physical theories classed as quantum mechanics^ into
which they introduced the theory of probability.

The theory of radiation and of the structure of matter has
been greatly affected by the development of the relativity
theory of Einstein. The adoption of the ether by Augustin
Fresnel and Clark Maxwell as the medium in which radia-
tion is transmitted led to the suggestion that, since the earth
was moving through the ether, the velocity of light as meas-
ured by an observer on the earth should be different if it were
measured in the direction of the earth's travel or across that
direction. This was tested by Albert Michelson in a series

114 THE PATH OF SCIENCE

of very careful investigations and no difference was found.
Repetitions of the experiment with Edward Morley, from
which it is generally known as the Michelson-Morley experi-
ment, gave essentially the same result. The ether is station-
ary ^vith regard to the earth, and, at the same time, no evi-
dence can be found that it is dragged with the planets. The
first solution of this paradox was given by Einstein in his
special relativity theory, in which he re-examined the founda-
tions of Newtonian mechanics.

The conception of space and time as independent frame-
works presupposes that we can compare time in different
points of space, and that the meaning of simultaneity at
points separated in space can be clearly defined. If we had
instantaneous signals, this would be self-evident; but even
light needs time to travel from one point to another. Ein-
stein took the fundamental result of the Michelson-Morley
experiment, that light has a velocity independent of the mo-
tion of the observer, as the basis of his new theory. AV^ith
the help of this definition, we can define the simultaneity of
t^vo events for a given observer. The laws of physics become
laws in space-time. The difference from classical physics is

given by a correction factor . /l wherein c is the ve-
locity of light and v the relative velocity of the object with
respect to the observer. Since the velocities of matter are
mostly very small compared to the velocity of light, the cor-
rection factor can be neglected in most practical cases, thus
leaving the bulk of physical experience uncorrected. How-
ever, it has served to explain some phenomena, such as the
motion of the perihelion of Mercury, and is of importance
in connection with the structure of spectral lines that arise
from the motion of electrons.

The classical laws of motion teach that no physical experi-
ment can distinguish a state of uniform velocity from a state
of rest. The rapid and complicated movement of a point on
the earth, for instance, is not felt as movement by the in-
habitants of the earth in spite of the fact that the point is

THE GROWTH OF PHYSICAL IDEAS 115

rotating around the center of the earth with a velocity at the
equator of over a thousand miles an hour. It is also moving
around the sun with a velocity of about eighteen miles a
second, and the whole solar system is moving among the stars
with even higher velocity, the rotation of the galaxy cor-
responding to a velocity for the solar system of over one
hundred miles a second. To the occupant of a point on the
earth, all these motions are unperceived as motion. Einstein
expanded his special theory and stated in his general theory
of relativity that even accelerated motion cannot be ascer-
tained by physical experiment. Sitting in an elevator that is
completely sealed, an observer cannot distinguish whether
the elevator is moving with accelerated velocity or whether
it is restinor in a sravitational field. Einstein's Qreneral rela-
tivity theory uses this idea to reduce all physical laws to one,
namely, de Fermat's law that the path between t^vo events
separating two points in space-time has stationary value com-
pared with other paths possible in the gi^avitational fields
given by all the effective forces. This theory allows the laws
of classical physics to be expressed in a very simple form;
moreover, it makes it possible to relate mass to energy. For
the transformation of mass into energy, Einstein deduced the
relation E = Amc-, where Am is the change in the mass in
grams, E the energy produced in ergs, and c is the velocity of
light. Since the velocity of light is 3 X 10^^ centimeters per
second, c^ = 9 X 10-^

Attempts to introduce the atomic structure of matter and
energy into a general field theory have not yet been success-
ful. At the present time we have dual theories in all fields
of physics— a relativistic continuous field theory, which uses
disturbances (waves) periodic in time and space and explains
the phenomena of interference, polarization, and diffraction,
common to all matter and all forms of energy; and an atomic
theory of matter and energy, which is basically discontinuous
and the laws of which are statistical in nature.

From the time of Newton to the beginning of the twen-
tieth century, astronomy was the science of position. It dealt

116 THE PATH OF SCIENCE

with the positions of the stars and with the movement of the
planets in tlie solar system. Astronomers spent the greater
part of their time in the computation of positions and in the
verification of their results. The greatest triumph of that
period was the calculation of the existence and orbit of a
planet beyond Uranus, a result obtained from slight devia-
tions between the observed position of Uranus and that which
was calculated from the influence of the other planets, and
the verification of this discovery by the observation of
Neptune when the telescope was directed to the calculated
position.

On the nature of the stars and the constitution of the
stellar universe, there was much speculation, but few facts
seemed to be obtainable. As an example of a thing that
must forever remain unknown, August Comte quoted the
chemical composition of the heavenly bodies. All this ^\as
changed by the application of the spectroscope to astronomy.
Von Fraunhofer had observed that in the spectrum of the
sun there were black lines, and Robert Bunsen and Gustav
Kirchhoff showed that these corresponded in position to the
bright lines in the emission spectra of some of the elements.
One of these was so unmistakable that its identification was.
certain— the double line in the yellow, to which was assigned
the letter D by von Fraunhofer, corresponding exactly to
the double emission line of sodium in the yellow. Jules,
Janssen and Norman Lockyer, pioneers in astronomical spec-
troscopy, observed in the spectrum of the chromosphere a
bright yellow line slightly on the gi^een side of the D line,,
which they ascribed to an unknown element; and Lockyer,.
greatly daring, named this element from the sun, helium..
In 1896 AVilliam Ramsay, who had identified argon in the
earth's atmosphere,* w^as looking for argon in the gas oc-
cluded in certain minerals when the spectroscope showed hiixt
that the long-sought-for helium had been found..

* Chapter VI, p. 134.

THE GROWTH OF PHYSICAL IDEAS 117

With the application of the spectroscope to the study of
the stars, the science of astrophysics was born. The chemical
composition of the atmospheres of the stars could be analyzed,
and in the case of the sun the most detailed investigations
were possible since the solar spectrum can be examined with
a dispersion and on a scale possible for no other source of
energy. With the increasing power of the great reflecting
telescopes and of the spectroscopes attached to them, it was
possible to learn much more about the structure of the
stellar universe.

Scattered through the sky and appearing on photographic
plates among the stars are patches of radiant material to
which has been given the name nebulae. The spectroscope
shows that some of these nebulae are glowing masses of gas
because their spectra are quite different from those of the
stars. They show the bright emission lines corresponding to
those emitted by a gas through which electricity is passing
in a vacuum tube. But by far the greater number of the
nebulae have spectra that correspond to what might be
termed an average stellar spectrum, especially those nebulae
that have a definite shape, often a spiral. In the greatest of
all these nebulae, that in the constellation Andromeda, the
100-inch telescope at Mount Wilson has shown the existence
of stars. It was possible from the nature of the stars observed
to calculate the distance of the Andromeda nebula, and it
proved to be nearly a million light-years away.

Man has traveled far from Tycho Brahe's picture of the
universe. First the earth lost its place at the center of the
solar system. Then it was realized that the sun was but one
star in the Milky Way, although, indeed, for a time it had
been believed that the sun and, therefore, the earth were near
the middle of the Milky Way. Now, with the Andromeda
nebula before our eyes, it is clear that the whole Milky Way
system is a great spiral nebula and that it is not alone in the
universe. There are other spiral nebulae composed of multi-
tudes of stars like those of the Milky Way. The Andromeda
nebula itself may be as great in its extension as our galaxy.

118 THE PATH OF SCIENCE

More and more, as these galaxies are being observed, it be-
comes clear that there are enormous numbers of galaxies and
that we have to think of the universe not as composed of
millions of stars but as composed of millions of galaxies, each
composed of hundreds of millions of stars.

When a star is observed with a spectroscope, the absorption
lines corresponding to certain elements are not found at
exactly the same wave length as those lines show in the
laboratory. The explanation of this was given as long ago
as 1842 by Christian Doppler, who showed that if a lumi-
nous body is moving in the line of sight, the frequency of
the light emitted will be changed by its velocity. If a star is
coming toward us, we shall receive more light waves of a
given ray in a given time than if the star were standing still.
The frequency, therefore, of the light will be increased, and
a spectral line will be moved toward the blue. If the star is
moving away from us, the spectral line will move toward the
red. When the light of the most distant nebulae was ob-
served, it was found that the lines were strongly displaced
toward the red and that this displacement increased in pro-
portion to the faintness of the nebula and therefore pre-
sumably in proportion to its distance. The effect is so great
that the picture obtained is that of an exploding universe,
one in which the outer nebulae are retreating in all directions
as if the whole universe were expanding. The mathematical
astronomers have analyzed the suggestion that the universe
may be considered to be expanding, using as their basis Ein-
stein's general theory of relativity, in which the four-dimen-
sional universe involving the three dimensions of space and
time may be considered a closed system and the expansion of
this closed system can be reconciled with the principles of the
general field theory.

Chapter VI

THE GROWTH OF CHEMICAL IDEAS

The fundamental principles of chemistry date not from
the seventeenth but from the end of the eighteenth and the
beginning of the nineteenth centuries. The delay in the
development of chemistry may be ascribed to two different
causes. The minor one is that experimental chemistry de-
mands access to equipment and materials to a much greater
extent than experimental physics. Galileo and Newton were
able to conduct experiments with very little apparatus in
ordinary buildings, and even in the nineteenth century Lord
Rayleigh w^as famous for the skill with which he made ob-
servations of the greatest precision with apparatus W'hich he
had constructed from pieces of wire, w^ood, and sealing wax.
But chemistry is the study of reactions, and it is necessary to
have materials which react and then to place them in suitable
environments, as, for instance, by heating them. Today we
take for granted a supply of pure chemical reagents, and we
can use very convenient methods of applying heat by gas
burners or electric furnaces. In the days when there were
no electricity and no gas, heat could be obtained only by
burning wood or coal, and no supply of suitable heatproof
glassware was available. It was necessary for the chemist in
most cases to prepare his own materials, and these were
usually very impure. Within our o^vn lifetime, indeed, work
in organic chemistry has been delayed by the inaccessibility
of starting materials and has only recently been facilitated by
their supply. A second and more important cause of the
delay in the advance of experimental chemistry was that it
got off to a wrong start twice. The earliest chemists were

alchemists, who were attempting to find the philosophers'

119

120 THE PATH OF SCIENCE

Stone or to transmute metals. They were, in fact, anxious
to work on applied chemistry, and their efforts to apply chem-
istry instead of observing and studying the facts delayed the
discovery of the nature of the reactions that constitute the
science of chemistry. Then when experimental chemistry got
under way, in the seventeenth century, its progress was gi^eatly
delayed by an entirely incorrect hypothesis that was adopted.

George Ernst Stahl, physician to the King of Prussia,
studied the phenomena of combustion and accepted the idea
suggested by J. J. Becker, one of the last alchemists, that they
were due to the loss by the burning substance of the prin-
ciple of combustibility, to which he gave the name phlogiston.
When flame is observed escaping from a piece of burning
wood, what is more reasonable than to assume that the prin-
ciple that renders the material combustible is escaping in the
flame? And this was the more reasonable because the alchem-
ists had laid great stress on the existence of various principles
in all things, the principle of combustibility being generally
termed sulfur by the alchemists. We now know, of course,
that combustion is the combination of the burning substance
with the oxygen of the air, but this idea was completely re-
versed by the followers of the phlogiston theory, even though
measurements of the change of weight during combustion
showed that the burning substance increased in weight. This
was explained by the ad hoc assumption that phlogiston had
a negative weight. Even Joseph Priestley, the English non-
conformist minister who discovered oxygen gas in 1774 simul-
taneously with Karl Scheele, insisted on calling it dephlo-
gisticated air, his idea being that this was the component of
the atmosphere with which the phlogiston united when it
escaped from a burning substance.

The true nature of combustion was demonstrated by
Lavoisier in 1772 as a result of quantitative measurements,
in which he found that the burning of sulfur and phosphorus
and the oxidation of metals resulted in an increase of weight.
He then repeated Joseph Priestley's experiments on the heat-
ing of mercuric oxide to obtain oxygen and showed that com-

THE GROWTH OF CHEMICAL IDEAS 121

bustion was due to a combination of the material with oxygen.
In 1789, the year of the French revolution, Lavoisier pub-
lished the work on which all chemistry is founded today and
freed the chemical world from its obsession with the phlo-
giston theory, which had delayed its progress for so long.

All the early work in chemistry had been concerned with
the nature of reaction, and after the experiments of Lavoisier,
which elucidated the properties of oxygen and its reaction
with hydrogen, carbon, and other elements, rapid progress
was made toward understanding not merely the nature of
reactions but the quantitative laws which govern them, so
that the principles of quantitative analysis could be laid
down. As a result of this, J. L. Proust, a French chemist who
was director of the Royal Laboratory in Madrid, was able to
show that a definite chemical compound always contains the
same elements combined in the same proportions by weight.
This law of definite proportions was the basis on which
Dalton founded his atomic theory.

John Dalton was a teacher of mathematics, physics, and
chemistry, chiefly in Manchester, but, as he says in his brief
biography, "occasionally by invitation in other places;
namely, London, Edinburgh, Glasgow, Birmingham, and
Leeds." Dalton considered Proust's law of definite propor-
tions and concluded that chemical compounds are formed by
the combination of certain unit weights of the elements. The
smallest possible unit he termed an atom, following Lucre-
tius; and he concluded that the atoms of the elements must
vary in weight, these atomic weights being basic physical
properties of the elements.

Jons Berzelius was the organizer of the science of chem-
istry. He was a medical man, teacher, and finally a professor
of chemistry at the College of Medicine at Stockholm. He
introduced the system of chemical nomenclature, of the
symbols for the elements and formulae for compounds, and
he developed great skill in chemical analysis, as a result of
which he determined the atomic weiofhts of the elements

122 THE PATH OF SCIENCE

with such precision that his determinations were not super-
seded for many years.

The analytical work in w^hich Berzelius displayed such sur-
passing skill could, of course, determine only the combining
equivalents of the atoms. The assumptions made by various
chemists as to the number of atoms which combine to form
a compound resulted in different values for the atomic weight.
If, as it w^as easiest to believe, one atom of hydrogen com-
bined with one atom of oxygen to form water, the atomic
w^eight of oxygen was 8. The solution of the difficulty could
have been found in the hypothesis of Amadeo Avogadro,
professor of physics at Turin, who introduced the idea of
the molecule as the smallest part of a substance which can
exist free in a gas and postulated that equal volumes of gases
under the same conditions contain the same number of mole-
cules. Unfortunately, however, although this theory was
published by Avogadro in 1811, it was nearly fifty years be-
fore its importance was generally recognized and the prob-
lem of the atomic weights of the elements was solved in its
present form.

As chemists became more and more interested in the study
of the innumerable compounds of carbon, they began to de-
vote their attention to the production of new substances,
that is, to synthesis. Throughout the second half of the
nineteenth century, the main advances in chemistry were in
the synthesis of new carbon compounds, in the field which is
now known as organic chemistry.

In the rise of organic chemistry, the greatest influence was
exerted by Justus von Liebig, professor of chemistry at Gies-
sen, who not only contributed much to the science by his
own studies but also was the teacher of the great school of
organic chemists that flourished in Germany in the nine-
teenth century. In 1836, A. W. von Hofmann, for instance,
entered the University of Giessen with the intention of
studying law, but under von Liebig's influence he changed
his field of work to chemistry, in which he became one of
the great discoverers in the field of organic chemistry. In

THE GROWTH OF CHEMICAL IDEAS 123

1845, Hofmann became professor of chemistry in the newly
founded Royal College of Science in London. One of his
students, W. H. Perkin, as a boy of seventeen discovered the
first synthetic dye. In 1864 Hofmann went to the University
of Berlin as professor of chemistry, and in his laboratory
were trained many of the chemists who established the Ger-
man dye industry.

In the early days of organic synthesis, the structure of the
compounds produced was very difficult to understand. In
1835, Friedrich Wohler, then teaching at Cassel, wrote to
Berzelius, under whom he had studied: "Organic chemistry
just now is enough to drive one mad. It gives me the im-
pression of a primeval tropical forest, full of the most re-
markable things, a monstrous and boundless thicket, with no
way of escape, into which one may well dread to enter."

We can easily understand this feeling of Wohler's. The
increase in the number of the compounds of carbon, which
have since shown such amazing proliferation, naturally ap-
palled chemists accustomed to think in terms of the simpler
inorganic chemistry. The difficulty, of course, was that
through the ''forest" of which Wohler wrote there w^as no
path blazed. No one had mapped a system of organic chem-
istry. The beginning of the making of this path was the
work of von Liebig and Wohler. Unlike as the two were,
von Liebig was justified when he wrote to Wohler: "When
we are dead, the bonds which united us in life will always
hold us together in the memory of men as a not frequent
example of two men who loyally, without envy or malice,
contended and strove in the same domain and yet remained
closely united in friendship."

The key to the understanding of organic compounds came
wdth the idea that certain groups of atom^ are to be found in
many compounds of cognate structure. Thus, if ethyl alcohol
and ethyl chloride are analyzed and their compositions writ-
ten, they will be represented as C2 He O and C2 H5 CI. Their
relationship becomes much clearer if w^e wTite these formulae
as C2 H5 OH and C2 H5 CI, from which w^e see that they

124 THE PATH OF SCIENCE

both contain the group C2 H5, which is known as the radical
ethyl. The importance of these radicals was first realized as
a result of the work of von Liebig and Wohler on the com-
pounds derived from benzoic acid that contain the radical
benzoyl, Ce H5 CO. Jean Dumas and P. Boullay had even
earlier recognized the existence of the ethylene radical, and
Bunsen found the cacodyl radical in the organic compounds
of arsenic, which he investigated. Berzelius, who at this
time was the recognized leader in chemical science, had
formulated the structure of inorganic salts as depending upon
the union of two electrically opposed components, these be-
ing the oxide of the metal and of the metalloid. Berzelius
applied this same idea to the structure of organic compounds,
formulating ethyl chloride as directly analogous to sodium
chloride. The great generalization of Berzelius was later to
be revived in the theory of electrolytic dissociation. But it
does not apply to organic compounds, and its advocacy by
Berzelius undoubtedly delayed the advance of organic chem-
istry for a number of years. The opposition to Berzelius
centered around two ideas. Von Liebig believed that the
properties of organic compounds depended upon the pres-
ence of radicals, so that ethyl chloride was cognate with ethyl
alcohol, since both of them contain the radical ethyl, rather
than with sodium chloride. Dumas, on the other hand,
classified organic compounds into types. Thus he found that
the progressive substitution of chlorine for hydrogen atoms
in acetic acid left the type of compound undisturbed. Mono-
chloroacetic acid, dichloro-, and trichloroacetic acid are all
acetic acids. The idea of types was extended by A. W.
Williamson, the predecessor of Ramsay at University Col-
lege, London. He considered alcohols, ethers, and acids to
belong to the water type of compounds; whereas A. Laurent
and C. F. Gerhardt regarded the amines as of the ammonia
type.

All this work was leading to the clarification of the struc-
ture of organic compounds, but our present structural
formulae we owe primarily to August Kekule and A. S.

THE GROWTH OF CHEMICAL IDEAS 125

Couper. Kekule wrote a most dramatic description of his
discovery. He was on a visit to London. He wrote:

I sank into a reverie. The atoms flitted about before
my eyes. I had ahvays seen them in movement, these little
beings, but I had never succeeded in interpreting the man-
ner of their movement. That day I saw how two small
ones often joined into a little pair; how a larger took hold
of two smaller, and a still larger clasped three or even four
of the small ones, and how all span round in a whirling
round-dance. I saw how the larger ones formed a row and
only at the end of the chain smaller ones trailed along.
The cry of the conductor, "Clapham Road," woke me up
from my reverie, but I occupied part of the night in put-
ting at least sketches of these dream-products on paper.
Thus originated the structure-theory.

While the molecules of a very large group of compounds,
the aliphatic compounds, could be built up as chains of car-
bon atoms, it was not possible to formulate in a similar
manner the aromatic compounds, which are characterized
by a relatively high proportion of carbon and never contain
less that six carbon atoms in the molecule. The simplest
member of this group is the hydrocarbon benzene. Benzene,
first isolated by Faraday, is shown by analysis to have the
composition Ce He- Since carbon atoms have a valency of
four, a compound with the composition Ce He should be
highly unsaturated, reactive, and unstable. The compound
C2 H2, acetylene, is, indeed, very unsaturated, reactive, and
unstable, as is evident when its structural formula HC^CH
is considered, for the two carbon atoms are attached to each
other by three bonds and can therefore add two atoms each
without dissociating. But benzene is not unstable or re-
active; it is stable and rather inert.

In 1865, Kekule, then professor of chemistry at Ghent,
was engaged one evening in writing his textbook. "But it
did not go well; my spirit was with other things. I turned
the chair to the fireplace and sank into a half-sleep. Again
the atoms flitted before my eyes." His imaginative eye,
sharpened by repeated visions of a similar kind, could by

126 THE PATH OF SCIENCE

this time distinguish large structures of compHcated con-
struction. He had seen rows of atoms linked together, but
never yet rings; nor had anyone else. This is how the idea
came to him: "Long rows, variously, more closely, united;
all in movement, wriggling and turning like snakes. And
see, what was that? One of the snakes seized its own tail
and the image whirled scornfully before my eyes. As though
from a flash of lightning I awoke." *

But the picture Kekule had seen of the snake that had
seized its own tail gave him the clue to the most puzzling
of molecular structures, the structure of the benzene mole-
cule. For it Kekule suggested a closed ring of six carbon
atoms, to each of which a hydrogen atom is attached:

A
HC CH

HC. €H
C
H

This formula interpreted the behavior of benzene and its
derivatives in a satisfactory manner. For instance, it ex-
plained the fact that when t^vo hydrogen atoms in benzene
are substituted by other atoms or radicals, three different
di-suhstituted compounds can be obtained. Kekule pointed
out that these could depend on the position of the two sub-
stituted atoms in the ring. When they were next to each
other, they could be called ortho; opposite to each other,
para; and in the position where they were separated by one
hydrogen, he used the term meta compounds:

HC^ ^CX

HC CH

1 1

HC CH

HC CX

HC CH

Ortho

Meta

Para

* John R. Baker, Scientific Life, p. 13, London, Allen and Unwin,
1942.

THE GROWTH OF CHEMICAL IDEAS 127

It was Kekule's pupil W. Koerner who gave the experi-
mental proof of this relation. He made the three isomeric
dibrombenzenes and the mononitro compounds derived from
them; and he found that the number of mononitro com-
pounds derived from each dibromo compound was that
which would be prophesied by the Kekule formula, and thus
he identified the position of the bromine atoms in the differ-
ent dibromo derivatives.

These theories of molecular constitution supplied the
chemists with the map and compass by which they could
penetrate that tangled forest of organic chemistry. They
could understand the difference between structural isomers;
that is, compounds of identical composition and molecular
weight but different chemical behavior. The first of these
isomers had been discovered by Wohler and von Liebig in
the pair cyanic acid and fulminic acid. Such isomerism was
now understood as being caused by a different linking of the
atoms in the molecule. A little later it became possible to
distinguish between isomers that differed only as the left
hand differs from the right. The organic chemists soon
evolved methods by which they could determine the posi-
tion of different groups in the molecule and could build
molecules according to plan.

As early as 1849, E. Frankland had been able to synthesize
hydrocarbons of the methane series. If, for instance, ethyl
iodide was heated with zinc, zinc iodide was formed, and
the two ethyl groups united to form butane. Frankland,
indeed, discovered the zinc alkyls and used them in syn-
thetic operations, an early suggestion of the most important
Grignard reaction, in which magnesium is employed instead
of zinc.

In 1877, C. Friedel and J. M. Crafts at the Sorbonne dis-
covered the reaction that is known by their names. In it,
alkyl groups can be introduced by treating a compound such
as benzene with an alkyl chloride in the presence of anhy-
drous aluminum chloride. About the same period also, the
value of the reactive methylene group was recognized, and

128 THE PATH OF SCIENCE

syntheses built on compounds containing it became of
general importance in organic chemistry. These synthetic
methods were satisfactory to the organic chemists as long as
they were dealing with the compounds derived from benzene
or from the heterocyclic ring structures, which, to some ex-
tent, simulate the properties of benzene; that is, as long as
organic chemistry used as its base materials the oils derived
from coal tar. But after the first World War, the great oil-
refining and chemical companies of the United States started
to study the possibility of using petroleum products as the
base for new groups of organic compounds, and the attention
of the manufacturing chemists became concentrated on the
aliphatic organic compounds, those composed of chains of
carbon atoms and derived from acetylene, natural gas, or
the decomposition products of petroleum. With these com-
pounds, it was found that reactions could be produced in the
gas phase with gieat facility, using catalysts that might be
solids, liquids, or even gases. As a result, the classical ali-
phatic chemistry ceased to have any relation to manufactur-
ing processes.

The standard method of preparing acetic anhydride, for
example, is by the treatment of acetyl chloride with sodium
acetate. The process for manufacturing acetic anhydride,
which is used on a large scale, however, bears little relation
to that classical reaction. In that process, acetic acid is cata-
lytically decomposed in the gas phase at a very high tempera-
ture to ketene (CH2CO), the inner anhydride of acetic acid;
and the ketene then reacts with the molecules of acetic acid
to form acetic anhydride. More and more reactions of this
type are taking the place of the classic organic syntheses and
are making available large quantities of substances that used
to be chemical curiosities.

Many of these new chemicals have a double bond in their
structure; that is, two carbon atoms are united not by one
but by two bonds. These compounds polymerize easily be-
cause one of the bonds is sufficient to hold the carbon atoms
together, while the other can supply a connection to link the

THE GROWTH OF CHEMICAL IDEAS 129

molecules of the substance together to form chains or net-
works of molecules, producing compounds having high mo-
lecular weights. Such compounds have long been known in
nature; molecules of sugar, for instance, polymerize to form
starch and cellulose. By this means, chemists have built up
a large group of so-called plastics— comY>ounds having a high
molecular weight and usually valuable properties comparable
with those of the natural products that have been of such
value to man throughout the ages, such as wood, wool, cotton,
and glass. The study of the plastics and of high-molecular
compounds generally is now a very important branch of
chemistry, and the ideas involved in the structure of polymers
are coming to the front in modern chemical theory.

The chemical reactions that occur in living organisms have
been studied primarily by chemical physiologists, and the
determination of the nature of some of the simpler of these
reactions will be discussed in the next chapter (page 169).
The identification of some of the compounds formed and
their synthesis in the laboratory have, however, been among
the triumphs of organic chemistry, which, indeed, owes its
very name to this field of work. The nitrogen-containing
compound urea was identified by von Liebig in the blood and
urine of mammals, in which it is the chief vehicle for the
elimination of the nitrogen produced by the katabolism of
the proteins. In 1828 Wohler synthesized urea, an event
that aroused great interest and some controversy since urea
had been considered a typical product of "vital" processes.
After von Liebig, the greatest name in this field of chemistry
is Emil Fischer, who, after acting as assistant to Adolf von
Baeyer at Munich, became professor of chemistry successively
at Erlangen, Wiirzburg, and Berlin. While studying deriva-
tives of hydrazine, he discovered that phenylhydrazine reacts
with sugars to form well-crystallized compounds, osazones.
Then he turned his attention to nitrogen-containing com-
pounds related to uric acid and showed that all of them
were derived from a base, purine, which he synthesized, wdth
many of its derivatives. Then he returned to the study of

130 THE PATH OF SCIENCE

the sugars and synthesized many of them, identifying and,
in many cases, preparing the stereoisomeric forms. The dif-
ficulties produced by fermentation in this work turned
Fischer's attention to the chemical ferments and enzymes,
in regard to which he and his coworker, E. Abderhalden, laid
the foundations of our present knowledge.

From the sugars and ferments Fischer transferred his at-
tention to the proteins. He succeeded in breaking down
these complex products of vital metabolism into amino acids
and other nitrogenous compounds, solving their constitution
and synthesizing them. He was thus able to prepare in the
laboratory polypeptides analogous to the natural proteins.

Other fields of the chemical study of naturally occurring
substances relate to the plant alkaloids, which are of great
pharmaceutical interest, and to the coloring matters of plants.
Perhaps the most striking examples of this field of chemistry
are the recent determinations of the structure of the vitamins
and the hormones derived from the ductless glands. The
industrial production of synthetic vitamin C (ascorbic acid)
and especially of vitamin Bi (thiamin) provides an adequate
supply of these necessary materials.

The properties of the compounds of carbon and their pro-
duction by synthesis are the field of organic chemistry. On
the other hand, the study of chemical reactions and of the
equilibria produced in those reactions is the field of physical
chemistry.

It had long been known that the progress of a chemical
reaction is influenced by the amounts of the reacting sub-
stances, but it was not until 1850 that the progiess of a
reaction was measured and the results expressed as a mathe-
matical equation. This was done by L. Wilhelmy at Heidel-
berg, who showed that when cane sugar was inverted by acids,
a reaction which can be followed with the polariscope, the
amount of cane sugar inverted in a unit time is proportional
to the amount of sugar present. Just at that time, the atten-
tion of chemists was largely directed to the discussion con-
cerning the structure of organic compounds, and it was twelve

THE GROWTH OF CHEMICAL IDEAS 131

years before the study of reaction velocities was resumed.
Then, in 1867, the full significance and generality of the
problem were recognized by two Norwegian scientists, C. M.
Guldberg and P. Waage. They stated that the velocity of a
reaction at constant temperature is proportional to the prod-
uct of the active masses of the reacting substances, this being
the fundamental law of chemical kinetics, which is generally
called the law of mass action.

With the discovery of this principle, many chemists
turned their attention to the velocity of reactions, which soon
centered upon the phenomenon of catalysis. This term had
been introduced by Berzelius for reactions the velocity of
which was greatly increased by the presence of small amounts
of foreign substances that apparently took no part in the
reaction and underwent no chang^e. The conversion of starch
into sugar, for instance, is accelerated by dilute acids. Hy-
drogen peroxide decomposes rapidly in the presence of finely
divided platinum, which also assists the oxidation of ethyl
alcohol to acetic acid. Berzelius said: "I don't believe that
this is a force quite independent of the electrochemical af-
finities of matter, but since we cannot see the reaction and
mutual dependence, it will be more convenient to designate
the force by a separate name." That name was catalysis.

\Vg have seen that Wilhelmy discovered the laws of chem-
ical kinetics in the study of the inversion of cane sugar, which
was catalyzed by acids. It was at Wilhelm Ostwald's labora-
tory at Leipzig, sixty years after the work of Berzelius, that
the study of catalytic phenomena was systematically brought
into the domain of chemical kinetics and investigated quanti-
tatively. Ostwald founded the greatest school of physical
chemistry and brought together the work of Guldberg and
Waage, of Willard Gibbs, J. H. van't Hoff, Svante Arrhenius,
and W. Nernst in his great textbook of general chemistry,
which, with the Zeitschrift filr physikalische Chemie^ sup-
plied the written sources through which physical chemistry
could be taught to the student.

Just as the work of Guldberg and Waage supplied the key

132 THE PATH OF SCIENCE

to the study of reactions in homogeneous systems, the phase
rule of Willard Gibbs opened the door to the effective analysis
of heterogeneous systems in which the reacting substances are
present in more than one phase— as solids and liquids, for
instance. Willard Gibbs published his work in the trans-
actions of the Connecticut Academy. Because of this rather
obscure place of publication and the mathematical form in
which it was developed, chemists were slow to recognize its
value. It was not until Ostwald published his translation of
Gibbs' papers in 1891 and H. W. B. Roozeboom, at the
beginning of the twentieth century, studied heterogeneous
equilibria on the basis of Gibbs' phase rule that it became
generally known to chemists and physicists as a principle
of the highest value in the classification of heterogeneous
equilibria.

In a general way, it may be stated that the effect of chang-
ing temperature, pressure, or concentration in any hetero-
geneous system would have to be considered a special prob-
lem for each system investigated were it not for the phase
rule. In any system, w^e have components— such as salt, water,
and acid; phases— gaseous, liquid, and perhaps several solid
phases; and variables— such as temperature, pressure, and con-
centration, which are known as degrees of freedom. The
phase rule, which states that the degree of freedom of the
system is equal to the number of components plus two minus
the number of phases present, enables any well-defined sys-
tem to be classified and analyzed without difficulty. This rule
has been of the greatest importance in many practical ap-
plications of chemistry, and, in particular, chemical engineer-
ing has made great use of it. All phenomena of precipitation,
evaporation, separation of salts, and compositions of alloys
are interpreted by Gibbs' phase rule. The great rise of in-
dustrial chemistry around 1900 was largely conditioned by
this chemical idea, which had remained in incubation for so
long a period between the time when it was conceived by
Gibbs and the time when it was generally adopted.

In the years between Gibbs' writing and the application of

THE GROWTH OF CHEMICAL IDEAS 133

his work, the physical chemists developed another great chem-
ical idea, the theory of electrolytic dissociation, first advanced
by the S\vedish chemist Svante Arrhenius. Arrhenius' theory
arose from the application of the gas laws to chemical solu-
tions by the Dutch chemist van't Hoff. Just as the pressure
of a gas is a measure of the concentration of the gas molecules,
so the osmotic pressure of a solution, which is the pressure
produced through a semi-permeable membrane that transmits
the solvent but not the molecules of the material dissolved,
is a measure of the concentration and, thus, of the molecular
weight of the substances present. In dilute solutions of salts
this principle, which held beautifully for solutions of sugar,
failed until Arrhenius introduced the conception that salts
in solution dissociated into unit particles that were oppositely
charged electrically. Faraday had already postulated such
charged particles to explain the conduction of an electric
current through a solution and had termed them ions.

It is now recognized that the simple picture developed by
Arrhenius is not adequate to account quantitatively for the
behavior of solutions of electrolytes, although his funda-
mental concept of dissociation is still the basis of the modern
theories of Peter Debye, E. Huckel, J. N. Bronsted, and
others. Today we do not consider the behavior of the single
ion, but the potential forces of the whole system of ions, in
which each is acted upon by the electrostatic field created by
the others. From such considerations, we can calculate with
reasonable accuracy many of the thermodynamic properties
of solutions, and can predict something of salt and ion ef-
fects as related to rates of reactions.

As the chemical elements were identified and their atomic
weights were determined, it became possible to discern a sort
of order in their properties. They could be classified into
families whose chemical properties were similar. Thus, there
are the alkali metals, the alkaline earths, the halogens, and
so on. The compounds of sulfur resemble those of oxygen
far more closely than they do those of nitrogen, which, how-
ever, are akin to those of phosphorus. As a result of similar

134 THE PATH OF SCIENCE

considerations, D. I. Mendeleev, professor of chemistry at
St. Petersburg, was led to classify the elements by plotting
properties which could be measured quantitatively, such as
the atomic volumes, against the atomic weights. The curves
showed that the same properties repeated periodically, and
Mendeleev classified the elements in what is known as the
periodic table. By extrapolating this table, he was able to
prophesy the existence of elements that had not yet been dis-
covered and to state their approximate properties. Several
of these prophesies were justified by the discovery of the ele-
ments that he had foreseen.

In the last years of the nineteenth century, two discoveries
were made that disclosed the existence of elements for which
there seemed to be no room in the periodic table. The first
was the discovery by Sir William Ramsay of the rare gases
of the atmosphere. In 1882 Lord Rayleigh started to re-
determine the density of oxygen and hydrogen and later ex-
tended the work to nitrogen, whose atomic weight is of
fundamental importance in connection with the determina-
tion of the atomic weights of many elements. He used ni-
trogen prepared from the atmosphere by the elimination of
the oxygen and of all other reactive gases, such as carbon
dioxide and water vapor, and also nitrogen prepared by the
decomposition of ammonia. To his astonishment, the at-
mospheric nitrogen was appreciably heavier than that pre-
pared chemically. After many checks, he discussed the matter
in 1894 with Ramsay, who investigated the nature of the
atmospheric nitrogen by causing it to react with metals, such
as magnesium, which combine with nitrogen. About one per
cent of the gas would not react, and this proved to be a new
gas having a higher density than nitrogen and a different spec-
trum. Moreover, this new gas ^vould not react with anything
at all, for which reason it was named argon, the "lazy" gas.
Following this discovery, Ramsay succeeded in isolating four
other gases having properties similar to argon— helium,*

* Chapter V, p. 116.

THE GROWTH OF CHEMICAL IDEAS 135

neon, krypton, and xenon. For a little time it looked as if
there were no place for them in the periodic table, and then
it ^\as realized that they formed a ne^v group of elements of
zero valency unable to form compounds. Instead of casting
doubt on the classification, they extended and enhanced its
validity.

An even more important discovery of hitherto unknown
elements was made when Pierre Curie and his wife isolated
from the residues of uraniimi ore the strongly radioactive
radium, of which the atoms ^vere found to be decomposing
and chans^ino^ into atoms of lower atomic ^veioht. Stimulated
by Roentgen's discovery of the x-rays in 1895, a number of
observers tested various fluorescent materials under the im-
pression that the origin of the x-rays might be connected ^vith
the fluorescence that the cathode stream excited in the glass.
Among these observers, Henri Becquerel used some beautiful
yellow-green crystals of uranium salts and found that when
these ^v ere wrapped in black paper and left in contact ^vith
a photographic film, they produced a blackening of the film
^vhen it was developed. This observation excited a good
deal of interest. Madame Curie and her husband studied
salts of other elements and discovered that thorium ^\'ould
also produce an effect on a film in the same ^vay that uranium
did and that the activity of different thorium and uranium
ores differed, some of them producing four or five times as
much effect as another ore containing the same amount of
metal. The tests finally indicated that the natural uranium
ore kno^vn as pitchblende contains something highly active.
Monsieur and Madame Curie undertook to analyze systemati-
cally about a ton of pitchblende ore, testing all the products
at each step for their activity as sho^vn in the production of
ionization in an electroscope, an eff^ect that proved to be
parallel to the exposure of a photographic plate. This re-
sulted in the isolation of two residues, in one of which the
barium of the pitchblende was isolated and in the other, the
bismuth; these residues ^vere forty to sixty times more ac-
tive than uraniimi. Ho^vever, normal barium and bismuth

136 THE PATH OF SCIENCE

showed no activity, so that it was concluded that these resi-
dues contained substances originally in the pitchblende that
were chemically very similar to barium and to bismuth.
These substances could be isolated by a long tedious process
of fractional crystallization, and w^hen it was carried out, new
elements were identified chemically. The one associated
with the barium was named radium^ and to the one found
with bismuth Madame Curie gave the name polonium^ from
her own country, Poland.

If the scientific world had been startled by the discovery
of the x-rays and the identification of the electron, this dis-
covery was even more astonishing. Here for the first time
were chemical elements that were obviously unstable. The
radium salts w^ere visibly decomposing. In the process of
decomposition, they emitted (1) beta rays, that is, electrons;

(2) gamma rays, which were soon shown to be x-rays; and

(3) a new radiation of short penetrating power but of great
intensity, to which the name alpha rays w^as given. These
rays, when studied in a magnetic and an electric field, proved
to be streams of positively charged particles. The relation
of their mass to their charge showed that they had a mass
either twice that of hydrogen, that is, they had an atomic
weight of 2, or they were atoms of helium that had a weight
of 4 but carried two positive charges. Sir Ernest Rutherford,
whose name now comes into the story, showed that the par-
ticles were, indeed, doubly charged atoms of helium and that
they turned into helium by picking up negative electric
charges by collision wdth hydrogen atoms, the helium being
identified by the bright yellow line with w^hich it glows and
which can be seen in the spectroscope.

The successive transformations of radium and polonium
were followed by chemists and physicists. It was sho^vn that
radium changes into several solids successively, and then into
a gas, which, in turn, changes into a solid and then into an-
other solid, and so on until, finally, the changes cease and a
stable atom of lead is produced. In this process, a series of ra-
diations are emitted— sometimes alpha rays, sometimes the

THE GROWTH OF CHEMICAL IDEAS 137

beta rays or electrons, and almost ahvays some of the gamma
or x-rays. Uranium has an atomic weight of 238. It passes
through five transformations in becoming radium, which has
an atomic weight of 225; and the radium passes through
nine transformations before becoming lead with an atomic
weight of 206, the last element before lead being polonium.
Thorium, in the same way, goes through a series of trans-
formations before the atom stabilizes as an atom of lead,
with an atomic weight, however, not of 206 but of approxi-
mately 208.

H. G. J. Moseley, a young student working with Ruther-
ford at Liverpool in 1913, measured the wave lengths of the
x-rays emitted by various elements when they were used as
the anti-cathode in an x-ray tube; that is, when the stream
of electrons falling upon them in the tube produced x-ray
emission. Using Rutherford's picture of the atom, Moseley
was able to show that the frequency of the x-radiation is pro-
portional to the square of the number of the element, the
number being the position of the element in the list of all
known elements; that is, the number of hydrogen, the light-
est element, is 1; that of helium, 2; of lithium, 3; and so on.
This discovery enabled Moseley to assign the numbers to all
the elements and thus to show what elements were missing
from the list, the numbers of the kno^vn elements being re-
lated to their chemical properties by the periodic classifica-
tion. When it was realized, after the ^vork of Rutherford
and Bohr, that an atom consisted of a positively charged nu-
cleus surrounded by electrons traveling in orbits, the total
charge of ^vhich was equal to that of the nucleus (Chapter V,
p. Ill), it became clear that the chemical properties of the
atom depend upon the electrons in the outermost orbit.
From the periodic classification, it "was realized that the in-
nermost orbit can contain at most two electrons, that the next
two orbits may contain eight each, and then the orbits con-
tain eighteen electrons, and so on. The number of electrons
in the atoms of each element can be stated definitely and
corresponds to Moseley's atomic number.

138 THE PATH OF SCIENCE

The structure of the chemical elements, therefore, the
charge on the nucleus, which is the same as that of the atomic
number, and the nuinber of electrons were all worked out.
One difficulty still remained, ho^vever. The atomic weights
of the elements are not the same as their atomic numbers.
The atomic weight, for instance, of helium is 4; its atomic
number is only 2; and it has only 2 electrons. If the hydro-
gen nucleus, which is generally called a proton^ has a weight
of 1, helium might be expected to have 2 protons in its nu-
cleus, ^vhich would give it t^vo positive charges. Having 2
electrons, it would be neutral, and its atomic weight should
be 2. The problem was solved when James Chadwick— like
Moseley and Aston, one of Rutherford's collaborators— found
that, under some circumstances, from atoms exposed to radia-
tion, particles could be obtained having a mass equal to
that of the proton but no electric charge. They are called
neutrons^ and they represent the missing units in the struc-
ture of the nucleus of the atom. The helium nucleus, for
instance, contains 2 protons and also 2 neutrons, these sup-
plying the necessary units of weight to account for the atomic
weight of the element as a whole.

The discovery of the neutron made possible an explanation
of the nature of the isotopes, discovered by Aston. The chem-
ical properties of an element depend upon the number of its
electrons, and the nucleus must have a number of protons
equal to the electrons to maintain electric balance in the atom
as a whole. The number of neutrons in an atoin, however,
do not affect the chemical properties, so that it is possible to
have two atoms with the same number of electrons, the same
atomic number, and the same chemical properties, but a
different total mass, because of a difference in the number
of neutrons present in the nucleus. Thus, in the case of the
two isotopes of neon that Aston discovered in the mass spec-
trograph, the particles in the rays had different masses. The
neon with an atomic weight of 20 has in its nucleus 10 protons
and 10 neutrons; its atomic number is 10, and it has 10 elec-
trons; but the neon with an atomic weight of 22 has the same

THE GROWTH OF CHEMICAL IDEAS 139

Structure as regards protons and electrons but has 12 neutrons
instead of 10. It differs from its twin only by being slightly
heavier, which makes it possible to achieve a separation in
the mass spectrograph.

The most interesting isotopic element discovered is the
isotope of hydrogen, which has an atomic weight of 2. It was
isolated by Harold Urey at Columbia University in 1931 after
its existence had been predicted by R. Birge and D. Menzel
at the University of California to explain the difference be-
tween the chemical atomic ^veight of hydrogen, w^hich repre-
sents, of course, the average weight of the atoms of the mixed
isotopes, and the atomic weight as determined in the mass
spectrograph, w^hich sho^vs only the weight of the proton it-
self. This isotope of hydrogen has t^vice the atomic weight
of hydrogen, since the neutron ^veighs as much as the proton,
and it is consequently not very difficult to separate it from
ordinary hydrogen. Moreover, the difference in ^veight is
sufficient to make it behave somewhat differently from hy-
drogen itself. The hydrogen isotope has even been dignified
by a separate name, deuterium.

As a result of the clarification of atomic structure, chemists
were able to make a new attack on the nature of the valence
bond. The valence bonds of Kekule and Couper w^ere rep-
resented by a line drawn bet\veen the symbols of two chemical
elements, indicating that the elements were connected in
some way, but the nature of the bond "^\^as completely un-
known. Indeed, its nature could not possibly be known be-
fore something was known of the structure of the atoms.

In 1916 G. N. Lewis worked out the electron theory of
valence, in which he emphasized the stability of the group of
8 electrons in the case of the lighter atoms. If the outer ring
contains exactly 8 electrons, the element has zero valence;
that is, it is one of the rare gases and is incapable of forming
molecules or compounds. AV'hen the outer electron ring of
the element contains less than 8 electrons, it can form com-
pounds in w^hich the electron ring of the one element is com-
pleted by electrons from another element, making 8 electrons

140 THE PATH OF SCIENCE

in all. On the basis of this theory, Lewis and Irving Lang-
muir were able to explain the structures of many chemical
compounds; and the Lewis model of the nature of valency
has been generally accepted. One difficulty in this explana-
tion, however, is that the electrons, depicted by Lewis as part
of the structure of the atoms, were bound in position, whereas
in the Rutherford-Bohr atoms, the electrons were free to re-
volve in their orbits. In fact, the atom as pictured by the
physicists has never been entirely reconcilable with the prop-
erties required by the chemists for their atoms. Recently,
however, the mathematical physicists appear to have found
the solution for such difficulties.* By the application of quan-
tum mechanics, it seems that the orbital atom may provide
the necessary mechanism for the formation of the electronic
bonds required for the stability of compounds.

Recent developments in nuclear physics have accelerated
the synthesis of chemistry and physics into one subject.
We have seen that the nuclei of the atoms are known to
consist of protons and neutrons, the total number correspond-
ing to the atomic weight of the element, whereas the number
of protons gives the atomic number. The atoms of nearly
all the elements are stable; only the few radioactive elements
disintegrate of their own accord. These radioactive ele-
ments, however, give out a great deal of energy when their
atoms disintegrate. The total energy given out by a pound
of radium in a year would convert nearly a ton of water into
steam, although it would take twenty-five hundred years for
half the radium to disintegrate. The radioactive elements,
therefore, indicate that an enormous amount of energy is
available if the nuclei of the atoms can be made to disinte-
grate.

Experiments by Rutherford and his associates showed that
this disintegration could be accomplished Avhen the nuclei
were struck by particles of very great energy, such as the alpha
rays from radium. The breakdown of nitrogen atoms by

* Chapter V, p. 113.

THE GROWTH OF CHEMICAL IDEAS 141

Rutherford in 1919 by these charged alpha particles was the
first example of the artificial disintegiation of atomic nuclei.

The next problem for the physicists was to produce artifi-
cially accelerated particles that would disintegrate nuclei in-
stead of using the alpha particles naturally emitted from
radioactive atoms. Attention was therefore turned to the
production of very high voltages, by ^vhich beams of elec-
trons and heavier particles, such as charged protons or deu-
terons— the nuclei of deuterium— could be accelerated. By
the use of large induction machines or high-voltage trans-
formers and valve tubes, it was found possible to obtain
electric pressures of the order of millions of volts. An im-
portant step was taken by E. O. Lawrence, who invented
the cyclotron. In it, a beam of atomic nuclei started at a
comparatively low voltage is accelerated by an alternating
electric field as the particles travel in a spiral orbit produced
by a magnetic field. As they swing around the circle, they
are continually exposed to acceleration and travel faster and
faster until finally they escape as a very rapidly moving
beam of atomic nuclei. The nuclei generally used are those
of hydrogen and helium and, especially, deuterium.

Using hydrogen nuclei (protons) produced in an electric
discharge and accelerated to high velocity by means of ap-
plied voltage, J. D. Cockroft and E. T. S. Walton in 1932
found that they could produce helium nuclei by the combi-
nation of protons with lithium nuclei. If we write this out
as an equation, and insert the weights of the particles in-
volved, we get the following:

Li + H = 2He

7.0182 1.0081 8.0080 [H- .0183]

Thus in this reaction the transformation of the lithium and
hydrogen nuclei into two helium nuclei leaves a surplus of
mass; and, since no other particles of matter are produced,
this mass must be converted into energ)\ The experiment
showed, indeed, that large amounts of energy "^vere produced
in the form of radiation. W't can calculate the amount of

142 THE PATH OF SCIENCE

energy produced from Einstein's equation (Chapter V, p.
115), stating that the energy produced, in ergs, is the change
of mass, in grams, multiplied by the square of the velocity of
light, which has the tremendous value of 9 X 10-^. When
atoms are disintegrated in this way, enormous amounts of
energy are released. No effective energy could be obtained
from such experiments, ho^\ ever, because only a very few of
the charged protons are captured by the lithium nuclei, and
so much energy is required to produce the beam of charged
protons that the procedure is quite hopeless as a means of
producing useful energy.

What is needed is a nuclear reaction that would be self-
propagating. When a piece of paper is lighted, only a small
portion burns initially, but the flame spreads until all the
paper is consumed. To get energy from the atom, an atom
is required that in disintegiating produces particles that will
disintegrate the next atoms they meet. In 1939 some experi-
ments showed that such a self-propagating reaction w^as pos-
sible for one of the uraniuin isotopes. There are several
isotopes of uranium; the coinmon one has an atomic weight
of 238. It is radioactive and disintegrates very slowly indeed
to form the radium series of elements. Another isotope of
uranium has an atomic ^veisrht of 235 and occurs to the ex-
tent of 0.7 per cent, or about 14 pounds per ton of uranium.
This isotope is disintegrated by the impact of neutrons, but
it does not disintegrate by simply emitting one or two par-
ticles. The atom actually splits in two, forming two new
elements that are first radioactive and then turn into stable
elements. This process is known as fission^ and when such a
catastrophe happens to an atom, a number of neutrons are
emitted. In the case of uranium 235 , as it is called, a neutron
starts the reaction, and then it is propagated by the neutrons
produced by fission. For this reaction to be propagated
through a mass, a certain quantity of 235 is required. Other-
wise, so many neutrons escape froin the outside into the air
that not enough are available to keep the disintegration go-
ing throughout the mass. Also, the 235 must be fairly pure.

THE GROWTH OF CHEMICAL IDEAS 143

If too much of the common isotope of uranium, the 238
isotope, is present, the neutrons will be absorbed by the atoms
of 238 and will not be available to disintegrate the 235.

The production of the atomic bombs that were dropped
on Japan depended on the working out of these problems on
an engineering scale. The uranium 235 was separated from
ordinary uranium by very laborious processes that produced
only a very small amount in each piece of apparatus, but by
building enormously large factories enough of the isotope
could be obtained for effective use in bombs. At the same
time, a new element, plutonium, was produced, this ma-
terial being made by the exposure of uranium 238 to neu-
trons supplied from uranium 235, the whole reaction taking
place in a structure called a pile.

Plutonium was first made in a cyclotron. A neutron adds
uranium to an atom of 238 to produce an unstable uranium
isotope, which emits an electron from its nucleus and turns
into a new element, number 93; and this in its turn emits
an electron and turns into plutonium, el-ement 94. Plu-
tonium is similar in its radioactive properties to uranium
235. Chemically, of course, it differs from uranium and
can be separated from it by chemical means. Plutonium in
sufficient quantity undergoes a self-prop'a gating fission like
uranium 235, so that atomic bombs can be made either by
the use of the uranium isotope 235 or by the use of plutonium
produced from uranium in a pile.

Chapter VII
THE GROWTH OF BIOLOGICAL IDEAS *

The sciences did not develop in a logical order. Without
previous advances in the physical sciences, biology could
make only limited progress. It was, however, one of the
first sciences to which serious study was devoted; whereas
chemistry, as we have seen (page 119), made very little ad-
vance until toward the end of the eighteenth century.
Twenty-two centuries before, in the fourth century B.C.,
Aristotle had already made considerable progress in the in-
vestigation of animal life. He was an acute natural his-
torian with a particular interest in the study of reproduc-
tion and development. In the following centuries biology
continued to be studied and taught in the museum at Alex-
andria. The store of biological knowledge continued to
grow until the time of Galen, in the second century after
Christ. Galen studied in Alexandria and his native Asia
Minor, and later in Rome. He was essentially a medical
man, but he made important studies on the anatomy and
physiology of various mammals. With his death the helix
of history had completed a revolution, and biology sank
back into insignificance.

It is true that knowledge of the work of Aristotle and Galen
was kept just alive during the long period of the Dark Ages,
but there was little or no progress. When the study of the
ancient authors ^vas revived, they came to be regarded as

* The reader who requires a textbook treatment of the history of
biology should use one or more of the following standard works:
W. A. Locy, Biology and Its Makers, New York, Henry Holt, 1915.
E. Nordenski()ld, The History of Biology, London, Kegan Paul, 1929.
C. Singer, A Short History of Biology, Oxford, Clarendon Press, 1931.

144

THE GROWTH OF BIOLOGICAL IDEAS 145

authoritative and not open to correction. It is not easy now-
adays to understand the spirit of those times, when biologists
were not expected to discover new facts, but only to expound
and illustrate the old opinions. Progress demanded not a
revival of the ancient knowledge but a breaking down of the
belief in the infallibility of the writers of antiquity. When
at last this tradition was broken, largely through the initiative
of the anatomist and physiologist Andreas Vesalius (page 77),
new knowledge of living organisms came rapidly; so rapidly,
indeed, that the old knowledge was soon of relatively small
importance, and it can scarcely be regarded as the basis of
modern biology. For this reason the biology of antiquity,
despite its considerable intrinsic interest, deserves only a
passing mention in a short history.

Modern biology may be said to have originated about 1537,
when Vesalius left his native Belgium, settled in the Uni-
versity of Padua, and began to become influential. From
then onward progress has been more or less continuous.
Nevertheless, it is convenient to divide the history of mod-
ern biology into earlier and later periods; and 1838 is a con-
venient year from which to date the later period. The first
decades of the nineteenth century were a time of steady ad-
vance in several departments of biology. In 1838 this steady
advance was suddenly followed by spectacular discoveries.
The cell theory, enunciated by Schleiden in 1838, led to an
outburst of cytological research; and the study of the minute
structure of organisms received a second great stimulus from
the re-introduction of the staining technique about a decade
later. Then in the fifties came the first understanding: of
the alternation of generations in plants, and Dar^vin's and
Wallace's theory of evolution by natural selection. All these
advances, following one another in rapid succession, make it
reasonable to date the later period of modern biology from
the year 1838. Our history will therefore be related in tw^o
sections, the first covering the three centuries that started in
15^7, and the second dealing with the rapid advances that

146 THE PATH OF SCIENCE

have occurred in many branches of biology between 1838
and the present day.

The rebirth of biolog)% then, started about 1537 in the
fields of human anatomy and physiology. Although A^esalius'
factual additions to knowledge ^vere considerable, his main
service to science ^vas to dare openly to doubt the authority
of the ancient writers. Greater discoveries than his were
made by others. Andrea Cesalpino, a man of extraordinarily
diverse interests in science, technology, and philosophy, de-
scribed the circulation of the blood in 1593 but, unfortu-
nately, failed to give particulars of the ^vay he got his kno^vl-
edge. It was left to the Englishman, William Harvey, to put
the physiology of the circulation on a really sound basis. His
Exercitatio anatomica de Motu Cordis et Sanguinis is de-
servedly one of the classics of science. He not only described
the path of the circulation but also made quantitative studies
of the amount of blood pumped by the heart. KnoTvledge
of human anatomy progressed rapidly, and by 1664 the
Oxford professor Thomas Willis had described the external
form of the brain and cranial nerves of man so accurately
that little of major importance has been added to his ac-
count. People had come at last also to understand that
glands are synthetic organs that pour out their secretions
through ducts.

The object of Vesalius, Willis, and most of the other early
anatomists and physiologists was practical. They wished to
improve the art of medicine. Before biolog)' as a whole could
flourish, it was necessary that the true spirit of science shoidd
develop, that the study of nature should be undertaken as an
end in itself. A nuinber of people ^vere studying and classi-
fying plants during the sixteenth century, but they ^vere do-
ing so mainly because they ^vished to identify the species that
provided drugs and other substances of material value to man.
So long as this was so, real progress in botany could not be
made. The first person to treat the subject as an inde-
pendent science, without regard to practical applications, ^vas

THE GROWTH OF BIOLOGICAL IDEAS 147

the versatile Cesalpino; and when he died in 1603, the stage
was set for rapid developments in this science.

Kaspar Baiihin of Basle made a fairly natural classification
of the higher plants, using the idea of genera and species,
thouoh without Qrivinor them names. That w^as at the bes^in-
ning of the century; toward its close Bachmann of Leipzig
(or Rivinus, as he called himself) suggested that no plant
name should contain more than two words. Half way through
the eighteenth century the great Swedish natural historian
Linnaeus applied Bachmann's suggestion to both the plant
and animal kingdoms, founding the universally accepted
principles of the nomenclatinx of organisms. His classifica-
tion of larger groups, ho^vever, ^vas defective. It was not
until near the end of the century that the first real attempt
to classify plants on a natural system was made by Antoine
de Jussieu, a member of the celebrated French family of
biologists of that surname.

The first fairly satisfactory classification of the animal king-
dom was made by that great comparative anatomist Georges
Cuvier in his Le Regne Animal (1816). Cuvier divided all
animals into four groups: the A^ertebrata, Mollusca, Articu-
lata, and Radiata. With the true mollusks he classified three
lots of organisms (the lampshells or "brachiopods," the sea
squirts and their allies, and the barnacles), which subsequent
research showed to be unrelated both to the mollusks and to
each other. The Articulata, again, have had to be dismem-
bered into two separate phyla, or main divisions of the animal
kingdom, the Annelida and Arthropoda. His Radiata was
not a natural group. It contained eight major phyla of the
animal kingdom and some lesser groups, the affinities of
which are still obscure.

Cuvier did much to increase knowleds^e of fossil animals.
The study of paleontology had begun long before. In 1669
that versatile Dane, Nils Steensen— Catholic priest and human
anatomist of the first rank— recognized the organic origin of
fossils and concluded that the rocks in which they occur had
been laid down as sediment in ^vater. Although he could not

148 THE PATH OF SCIENCE

know it, he thus originated that branch of knowledge in
which the theory of evolution would one day find its firmest
basis. De Buffon, an imposing figure of eighteenth century
science, considered that a certain amount of change occurred
in the form of organisms with the passage of time, but he did
not formulate any systematic theory or explain the causes.
Near the end of the century Immanuel Kant, the great phi-
losopher, allowed the possibility of evolution in his Critique
of Judgmentj and Charles Darwin's grandfather was already
a firm believer in the gradual adaptation of organisms to their
needs through the inheritance of what were later to be called
acquired characters. So also was the brilliant though specu-
lative Lamarck, although his ideas on the subject did not
attract a lot of attention at the time. More important than
any of these for the firm foundation of the theory of evolution
was a clergyman and economist named Thomas Malthus. He
was not himself a student of evolution or even of biology; he
was interested in the pressure of human population on the
available means of subsistence. But his writings on the sub-
ject were later to influence both Charles Darwin and Alfred
Russel Wallace, whose theory of evolution was to have such a
profound effect on biological thought sixty years later.

Modern ideas on evolution are closely bound up with our
knowledge of heredity, but in the eighteenth century that
subject was illuminated by only a single glimmer of light.
Just the very beginnings of knowledge were visible in Joseph
Koelreuter's experiments on hybridization. But no one then
could aruess what wonders Mendel and his successors would
do with the numerical analysis of results in this field. Koel-
reuter made a start along a line that did not begin to in-
fluence thought on the causes of adaptation until long after
the main battle for evolution had been fought and won.

Understanding of the processes of reproduction came very
slowly. A Dutch student, Hamm, discovered spermatozoa
in 1679. In the next century Spallanzani filtered semen and
showed that fertilization cannot take place unless spermatozoa
are present in it; but he did not conclude that they were the

THE GROWTH OF BIOLOGICAL IDEAS 149

actual fertilizing bodies. Reproduction could not be seri-
ously investigated until it was known for certain whether
organisms arise only from pre-existent organisms or whether,
on the contrary, they are sometimes spontaneously generated
from non-living matter. Harvey himself in 1651 announced
that every organism originates from an egg (though he never
saw the tgg of mammals); and ten years later Redi, physician
at the court of Florence, showed experimentally that larvae
appear in rotting meat only if flies lay eggs on it. That re-
markable man John Needham, an English Catholic priest
living on the continent, performed experiments nearly a cen-
tury afterward that caused him to be a firm believer in spon-
taneous generation. Toward the end of the eighteenth cen-
tury Spallanzani boiled various organic materials in airtight
containers and showed that life did not originate in them.
His experiments were so carefully done that they might have
settled the matter, but, as we shall see (page 166), the subject
was raised again much later. The Mammalian egg was first
seen in 1827 by the Esthonian K. E. von Baer, who also
made marvelously exact studies of the development of various
animals and may be regarded as the father of modern de-
scriptive embryology.

It is not only from eggs, however, that animals arise. This
had been shown toward the middle of the eighteenth century
by a Genevese naturalist, Abraham Trembley, who was acting
as tutor in a family living near The Hague. Trembley ob-
served some remarkable polyps in water taken from a ditch
and studied them with such profundity that his work is quoted
in modern textbooks not as a historical curiosity but for its
sound information on an important subject. He was the
first to show that certain animals can be multiplied artifi-
cially by cutting them into pieces, and he made a careful
study of the processes of regeneration. His friend Lyonet, a
Frenchman living at The Hague, made equally exact studies
in a different field. His description of the anatomy of the
goat-moth caterpillar is an example of accuracy and careful
observation that is thought by many good judges never to

150 THE PATH OF SCIENCE

have been surpassed to this day, although others before him—
especially that unhappy Dutchman, Jan Swammerdam— had
done magnificent work on insect anatomy. Such men as these
show how wrong it is to adopt a cynical or contemptuous atti-
tude toward the biologists of the seventeenth and eighteenth
centuries.

Trembley made a marvelously detailed study of the natu-
ral budding of his little fresh-water polyp. Hydra. He showed
how a small part of the body wall protrudes, develops new
parts, and becomes a new individual, which separates. His
work on this subject actually proved that there is a real
epigenesis or increase in complexity during development.
But he was influenced so much by the belief of his friend
and compatriot Charles Bonnet in preformation that he
never relinquished belief in it. Bonnet had shown that plant-
lice multiply without the intervention of a male parent. He
was struck by the high degree of development of the young at
birth and knew that in many insects each stage of develop-
ment is enclosed within the skin of the previous stage. He
generalized from these facts and imagined that each genera-
tion of organisms was folded up in a minute form within the
reproductive bodies of the previous generation. Develop-
ment, then, was only an unfolding, not a real increase in com-
plexity. Extending this idea still further, he imagined that
all subsequent generations were already folded up within the
first female of each species that existed on the earth. This
emhoitement of generation within generation was widely be-
lieved during the eighteenth century. Although Trembley's
observations were sufficient to disprove it, it was the writings
of the placid Caspar Wolff that at last made people reject
preformation and accept epigenesis. Working first at Halle
and later in St. Petersburg, Wolff showed that there is a gen-
uine increase in complexity in the development of both
plants and animals and not a mere unfolding of preformed
parts. His work was scarcely noticed until the beginning of
the nineteenth century, after his death. AV^olff paved the way

THE GROWTH OF BIOLOGICAL IDEAS 151

for von Baer and other great descriptive embryologists of the
nineteenth century.

Scarcely anything was known about the function or sig-
nificance of flowers until toward the end of the seventeenth
century, when people at last began to realize that the stamens
and pollen could be regarded as male and the style, ovary, and
ovule as female. This knowledge came from the work of
the English medical practitioner Nehemiah Grew and the
Tubingen professor, Camerarius. The latter removed the
male flowers of plants in w^hich the sexes are borne sepa-
rately and found that fruit was not set. It was in the sixties
of the eighteenth century that the professional botanist Koel-
reuter first showed clearly that certain plants are pollinated
by the wind and others by insects. At the end of the century
the hermit-like Christian Sprengel made a wonderfully exact
study of insect pollination and the devices by which plants
escape self-fertilization.

Understanding of the significance of leaves came later than
that of flowers. In the first half of the seventeenth century
the mystical chemist van Helmont had made one very con-
crete observation: a willow watered only with rain water
gained 159 pounds, while the soil contained in the bowl in
which it grew lost only three ounces in dry weight. No one
followed up this observation until in 1727 Stephen Hales, a
Middlesex clergyman, published a work of genius called
Vegetable Staticks, in w^hich he showed that plants absorb air
through their leaves and that part of their substance is de-
rived from the air so absorbed. This work marked the origin
of knowledge about the nutritive function of leaves. Hales
also measured the transpiration of water through plants and
studied root pressure.

In the second half of the eighteenth century the Unitarian
clergyman Joseph Priestley showed that air that had been
"injured" by the burning of candles could be made suitable
for animal respiration by keeping green plants in it; in fact,
green plants give off the gas that we now call oxygen. Jan
Ingenhousz, a Dutch doctor, showed in 1779 that plants only

152 THE PATH OF SCIENCE

give off "dephlogisticated air" in sunlight; in darkness, on
the contrary, they produce the gas that we call carbon dioxide.
These discoveries were not fully understood at the time. We
now know, of course, that green plants take up carbon dioxide
from the air through their leaves and under the influence of
sunlight build the carbon into the substance of their tissues.
In both light and dark they use oxygen and produce carbon
dioxide in respiring, just as animals do, but it is only in dark-
ness that the carbon dioxide is passed out into the air, for it
cannot then be used as a source of nourishment. It was not
until the beginning of the nineteenth century that the Swiss
investigator Nicolas de Saussure put the subject of plant
respiration and nutrition on a firm basis by means of quanti-
tative studies.

Meanwhile something was being learned about the respira-
tion of animals. Up to the middle of the seventeenth century
no one had the slightest idea why one must breathe to live;
respiration was not in the least understood. In 1660 Robert
Boyle, the famous chemist, showed that mice and sparrows
die in partial vacua. Eight years later a more fundamental
discovery was announced by John Mayow, the lawyer and
Oxford don (though Boyle was probably partly responsible
for it). It was shown that it is not air as a whole, but some-
thing in air, that is necessary for life. Mayow called that
something igneo-aerial particles; it was, of course, oxygen.
Nearly a century then elapsed without further discoveries
being made on this momentous subject. At last Joseph
Black, professor of chemistry at Glasgow, showed that ''fixed
air" (carbon dioxide) is a product both of combustion and
of respiration. Not long afterward a young Scottish medical
man Daniel Rutherford showed that "fixed air" is not the
only irrespirable matter in air; but he missed the actual dis-
covery of nitrogen. It was in 1780 that the fundamental dis-
covery about respiration was made by the famous French
scientists Lavoisier and Laplace: "Respiration is therefore
a combustion, slow it is true, but otherwise perfectly similar
to the combustion of charcoal." They had realized that

THE GROWTH OF BIOLOGICAL IDEAS 153

both burning and respiration are examples of oxidation. The
old ItaHan biologist Spallanzani corrected their one big error
not long before he died at the end of the century: the com-
bustion does not occur in the lungs, as Lavoisier and Laplace
had thought, but in the various tissues of the body.

The cell theory was first foreshadowed in the seventeenth
century. The English microscopist Robert Hooke described
the cellulae of cork; the Italian Marcello Malpighi, the ultric-
ulae of various plants; and Nehemiah Grew, their cells or
bladders. The Dutch petty official Anton van Leeuwenhoek
frequently figured cells. He also discovered blood corpuscles
and saw the nuclei of those of fishes, but the time was not ripe
for an understanding of the fact that both plants and animals
consist of cells. The follow-up of these seventeenth century
discoveries was slow. Half way through the eighteenth cen-
tury Caspar Wolff, the epigenesist, held that both plants
and animals consist of ampullae, but rigid proof was lacking
and the science of cytology had yet to be born. At the be-
ginning of the nineteenth century a Frenchman, Mirbel,
maintained that the cell is the basis of all structure in plants.
That extraordinary and erratic genius Lorenz Oken, amid a
maze of fantastic writings, claimed that all organic beings—
not plants alone— originate from and consist of little blad-
ders.

About the same time advances were made in other branches
of what we should now call histology and cytology. The
young Professor M. F. X. Bichat— he was to die almost at
once, at the age of thirty— was making the first comprehen-
sive classification of the tissues of the human body, strangely
enough, without using the microscope. In 1825 a much-over-
looked French scientist, F. V. Raspail, introduced the use of
iodine into microscopical studies to show the distribution of
starch in tissues by its intense blue reaction. He thus founded
the science of histochemistry , and went on to devise tests for
other substances occurring in plant and animal tissues.

From about 1830 onward cytology progressed rapidly, as
though in anticipation of the events of 1838. The versatile

154 THE PATH OF SCIENCE

Scottish botanist Robert Brown (as eminent in plant geog-
raphy as in microscopical studies) recognized the nucleus as
a regular feature in plant cells. It had already been named in
1823, but the universality of its occurrence had never been
realized. Attention had been focused on the cell wall, a mere
lifeless box, and not on the living substance within. The
most obvious object in the living substance within the box
is the spherical or oval nucleus, and it is perhaps not strange
that the nucleus attracted attention before the substance in
which it was embedded. Now at last the substance itself was
studied, by the French zoologist Felix Dujardin, who called
it sarcode. His description of it was remarkably accurate.
"I propose to give this name," he wrote, "to what others have
called a living jelly— this viscous, transparent substance, in-
soluble in water, contracting into globular masses, attaching
itself to dissecting needles and allowing itself to be drawn out
like mucus; occurring in all the lower animals interposed be-
tween the other elements of structure." We could hardly do
better today in so few words, though nowadays we have nu-
merical data for viscosity and elasticity, and we should not
restrict the substance to the lower animals. Dujardin's word,
however, did not stick. The Czech investigator Johannes
Purkinje introduced protoplasm, and this caught on some
years afterward when the great cytologist Hugo von Mohl of
Tubingen applied it to the same substance in plants.

Purkinje did something a good deal more important than
introduce a useful new word. He pointed out that the skin
of animals, especially embryos, consists of cellulae like those
forming the connective substance or parenchyma of plants.
The stage was now set for the enunciation of the cell theory.

It was in October 1838 that the ex-lawyer M. J. Schleiden
and the anatomist Theodor Schwann dined together in
Berlin. They were a strangely assorted pair. The volatile
Schleiden, having shot himself in the forehead and recovered,
can have had little in common with the placid Schwann apart
from their intense interest in the minute anatomy of organ-

THE GROWTH OF BIOLOGICAL IDEAS 155

isms. Schleiden described to Schwann the nucleus of plant
cells, and Schwann at once recognized it as corresponding to
something with which he was familiar in cells of the spinal
cord of Vertebrates. The two men repaired forthwith to
Schwann's laboratory in the Anatomical Institute of the Uni-
versity. Schwann showed his friend the cells of the spinal
cord, and Schleiden at once recognized the nuclei as corre-
sponding to those with which he was familiar in plants. Due
recosrnition must be g^iven to the researches of those who had
preceded them in cytological investigations, but this occasion
may nevertheless be justly regarded as marking the first gen-
eral formulation of the cell theory. The two men published
separately. They made big mistakes, but the cell theory—
the theory that plants and animals simply consist of cells and
the products of cells— must properly be ascribed to them.

Throughout the forties discoveries followed one another
quickly. Mohl came to regard cell division as the usual means
of production of new cells. The Swiss zoologist von Kolliker
showed that spermatozoa are cells, not mere parasites in
semen. His friend and compatriot Karl Nageli witnessed
nuclear division and was the first to glimpse the chromo-
somes. It was these two friends, more than anyone else, who
established one of the profoundest truths in biology: that the
egg is itself a cell and gives rise to the cells of the new indi-
vidual by repeated division. (It is true that Schwann had
already regarded the egg as a cell, but he did not understand
how new cells arise.) It was not until the fifties, however,
that it became generally accepted that cells never arise except
from pre-existing cells, and not until the sixties that proto-
plasm was called "the physical basis of life," and the cell "a
lump of nucleated protoplasm."

Much was being learned, then, about the minute structure
of animals; something also about the physical properties of
protoplasm; and its chemistry was not being neglected. Fried-
rich Wohler, the distinguished German chemist, had already
synthesized urea from inorganic components in 1828 and thus
shown that there was no sharp distinction between organic

156 THE PATH OF SCIENCE

and inorganic compounds. Raspail was making advances
by applying chemical color tests to thin sections of plant and
animal tissues, and the word protein was coined. Just at
the end of the forties, however, a striking technical advance
w^as made, which greatly encouraged the study of structure
while turning attention away from the study of substance.
This was the rediscovery of staining. Dyes had been used
sporadically in biological microtechnique a long time before,
but the biologists of the day did not know this. One after
another they began to rediscover what had been forgotten
and to apply it very much more actively than it had ever
been applied. The different constituents of tissues and cells
have extraordinarily different affinities for different dyes; and
by a little experimenting one can soon learn to make one part
of the cell stain in one color and another part in another.
One of the great difficulties in studying protoplasm had been
its transparency. That difficulty was now removed at a stroke,
and a clear insight was given into the minute structure of
organisms.

Dyes, unfortunately, tell us little about chemical composi-
tion, and the study of substance soon became overshadowed
by that of structure. Raspail's work with real chemical tests
was overlooked, and microscopists began to become amateur
dyers. Then came Darwin with his Origin of Species; and
morphology— the study of form— received a second powerful
stimulus. People began to think that the main purpose of
biology was to exhibit the evolutionary relationships of or-
ganisms, and that could be done by the study of structure,
without much attention being paid to substance or function.

In recent years there has been a healthy tendency to revert
to the study of substance instead of concentrating exclusively
on structure. All sorts of interesting^ methods have been
used to find out more about the actual substances of which
cells are composed. Some of these methods are actually new;
others are revivals of very old ones. One of them, micro-
incineration, actually originated with Raspail in the eighteen
twenties but has only recently been developed. Thin slices

THE GROWTH OF BIOLOGICAL IDEAS 157

of plant and animal tissue are heated in an oven until all the
organic matter is burned away and only inorganic ash is left.
The process is so carefully carried out, however, that the ash
remains exactly where it was, and the microscope reveals the
exact location of the inorganic constituents within individual
cells.

America has led the world in originating and developing
novel methods for investigating the substances of which the
cell is composed. Professor R. R. Bensley of Chicago, youth-
ful despite his years, has been and still is a pioneer in this
work. It was he who first showed how the minute com-
ponents of cells can be separated from one another by pass-
ing: tissues throuo^h fine sieves and then centrifusrino^ the ma-
terial at carefully regulated speeds. In this way some of the
most elusive cell constituents, previously only peered at under
the highest powers of the microscope, have been obtained in
masses that one can hold in one's hand. Instead of having
to rely on conjecture as to their composition, one can now
subject the material to direct chemical analysis.

But we must return to the outburst of discovery in various
fields that followed the formulation of the cell theory. The
phenomena of reproduction began to be put upon a cellular
basis. In 1855, for the first time, the German botanist
Nathaniel Pringsheim saw the essential feature in the act of
fertilization. As early as 1823 the microscopist Giovanni
Amici had observed the tube formed by the pollen grain and
seen it enter the ovule. Pringsheim now saw the cellular
nature of fertilization. He was working with Vaiicheria,
one of the lowly plants that form masses of branching green
threads in our ponds and ditches. He found that two cells,
the active male spermatozoid and the female ovum or egg,
fuse together to form a single cell and that the single cell
grows and differentiates until it becomes a new plant indi-
vidual. Spermatozoa had been known since the seventeenth
century and the corresponding spermatozoids of ferns since
the forties, and it seems rather surprising that an understand-
ing of the general principles of fertilization came so slowly.

158 THE PATH OF SCIENCE

It was not until the seventies that the Swiss scientist Hermann
Fol actually saw the spermatozoon of the starfish enter the
egg and thus showed for animals, as Pringsheim had shown
for plants, that fertilization consists of the fusion of two cells.

Meanwhile, the fundamental principles of the reproduc-
tion of plants were at last being discovered. A considerable
obstacle had to be overcome before progress could be made
in this subject. It had been supposed, quite naturally, that
the ovule was to a plant what the egg is to an animal. It was
an amateur botanist ^vho made all the fundamental discov-
eries that exposed the falsity of this view. Early in the fifties
Wilhelm Hofmeister, a music-seller, showed that mosses and
ferns exhibit an alternation of generations: that the spore of
a fern plant does not grow into another fern but into a com-
pletely different kind of plant, which itself reproduces sex-
ually to produce the fern plant once more. That was remark-
able enough, but Hofmeister went straight on to show that
there is an exactly comparable alternation of generations in
the flowering plants: part of the ovule is actually another
generation living parasitically on the parent that produced
it. This was one of the most important botanical discoveries
ever made, and it was all the more noteworthy because Hof-
meister did his work at a time when the actual process of
fertilization was not understood in either plants or animals.
Hofmeister, who was self-taught and had had no academic
training, now became a professor of botany at a great Ger-
man university.

Attention now began to be focused on nuclei. When
nuclear division occurs, chromosomes become apparent.
Chromosomes are colorless and transparent, but they have
an intense affinity for many ordinary dyes. Indeed, it is for
that reason that they are called by a name that means color
bodies. They had been glimpsed by Karl Nageli early in the
forties; now, owing to the rediscovery of staining, they had
become one of the easiest things in the cell to study. In the
seventies the German botanist Eduard Strasburger made out
the principal features of nuclear division in plants, and shortly

THE GROWTH OF BIOLOGICAL IDEAS 159

afterward the process was found to be essentially the same in
animals. Each chromosome divides longitudinally at cell
division, and of the two halves one goes into each daughter
cell to help reconstitute a new nucleus. About the same
time the German biologist Oscar Hertwig made the momen-
tous discovery that the essential feature of fertilization is
the fusion of two nuclei, one derived from each parent. It
was in the eighties that the Belgian zoologist Edouard van
Beneden made one of the most fundamental discoveries of
cell science: each nucleus in the body contains two packs of
a definite number of chromosomes, the number beino;- con-
stant throughout all the cells of the body in each species, ex-
cept the spermatozoon and egg, which have only one pack
each. The significance of fertilization now began to become
apparent; it brought two packs together again.

People were not slow to see that the extraordinarily precise
behavior of the chromosomes must indicate some function of
significance for life; and it was suggested that they were con-
nected with heredity. So they are, and the knowledge that
would have proved it was already lying on the dusty shelves
of the libraries of Europe. But no one read the necessary
paper. An almost unknown Austrian biologist, the monk
Gregor Mendel, had written it in 1866. It had been pub-
lished in an obscure journal and sent to London and else-
where; but scarcely anyone paid any attention. His paper
was independently rediscovered in 1900 by three scientists in
different parts of Europe; and it was at once realized that a
very important discovery had been made, so important, in-
deed, that the study of heredity is to this day often called
Mendelism.

Mendel worked mainly with edible peas, which he grew
in the garden of his monastery. His experiments were novel
in that he crossed plants differing in one or a few sharply
contrasting characters; and these he followed through, gen-
eration by generation, always counting accurately the number
of plants showing each character. It was particularly his
analysis of the ratios in which the characters reappear that

160 THE PATH OF SCIENCE

brought him posthumous fame. He showed that the genes,
as we now call the units responsible for heredity, do not in-
terfere with one another when they come together at fertili-
zation. A hybrid inheriting genes for both tallness and
dwarfness does not have genes for medium size in its germ
cells: on the contrary, each of its offspring inherits from it
only tallness or dwarfness. When Mendel's paper was dis-
covered, it was quickly shown that his laws of inheritance,
as they came to be called, were not soinething peculiar to the
edible pea but were of universal application to plants and
animals, including man.

The paper was discovered in 1900, and two years later a
fact of first-rate importance was pointed out by W. S. Sutton
of Columbia University. The way in which the chromo-
somes are distributed from parent to offspring was known.
Sutton pointed out that it was exactly the same as the way
in which the genes are distributed, according to Mendel's
findings. Mendel had died in 1894, a few years before van
Beneden had made his discoveries. Had he lived those few
years, Mendel might perhaps have forestalled Sutton. But
the last years of his life were so much occupied with the
financial affairs of his monastery that it is unlikely that he
kept in touch with chromosome research.

It was already known in 1901 that the sexes differed slightly
in their chromosome complement, and it was not long before
people realized that chromosomes are not only the bearers of
the genes for ordinary characters, but also the determinants
of sex. A few years later an American biologist began study-
ing inheritance in a little fly rather similar to the housefly but
smaller, called Drosophila. This animal presents extraordi-
nary advantages for the study of heredity. It can easily be
kept in large numbers in the laboratory, the reproductive
cycle from one generation to the next is very short, and the
chromosomes are few. It has taught us more about heredity
than any other organism. A group of workers centered
around T. H. Morgan at Columbia University began to make
marvelous discoveries. It had been known for some time

THE GROWTH OF BIOLOGICAL IDEAS 161

that certain genes behave under certain circumstances as
though they were linked to others in heredity. Soon it be-
came apparent that the number of groups of linked genes is
the same as the number of different chromosomes (only four
in each cell, in Drosophila). Morgan and his collaborators
were soon able to say which chromosome was concerned with
the inheritance of which group of linked genes and, further,
in what order the genes were arranged along each chromo-
some. They could say that at this point on a given chromo-
some was the gene that expresses itself most obviously by its
effect on the shape of the wings; here, farther along the same
chromosome, another affecting the size of the legs; farther
again, a gene affecting body color; and farther still, one af-
fecting^ the size of the winsjs; and so on for hundreds of other

genes.

The evidence for the arrangement of the genes in a certain
order along the chromosomes was entirely indirect. The
chromosomes looked more or less the same all along their
length; there were no little marks that might actually be the
genes. The complicated indirect evidence was obtained, like
Mendel's, from the counting of the numbers of individuals
showing various inherited characters in each generation, not
from a minute study of the chromosomes themselves. It was
not until the nineteen thirties that final ocular proof of the
chromosome theory of heredity was obtained. It became
known that some curious objects in certain cells of Drosophila
and other flies were nothing but gigantic chromosomes, about
one hundred times as long as normal ones. They are like
tapes with stainable marks across them. These marks are
something like the divisions on a measuring tape but differ
in that some are thick and some thin; and these thick and
thin marks follow one another in a resrular order. That resf-
ular order is the same in very nearly all the corresponding
chromosomes in the cells of all the flies of the same species,—
very nearly, but not quite— and the exception gave the clue
to a most important discovery. A few peculiar specimens of
Drosophila were known, in which the ordinary indirect evi-

162 THE PATH OF SCIENCE

dence suggested very strongly that some of the genes, cor-
responding to a short length of one chromosome, were the
"wrong" way around. It occurred to T. S. Painter and his
associates at the University of Texas to look at the giant
chromosomes of these particular specimens. In his micro-
scope he saw for the first time concrete proof of the chromo-
some theory of heredity: the thick and thin marks were in
fact arranged the wrong way around in part of the chromo-
some concerned.

Our modern understanding of heredity has thrown a strong
light on the causes of evolution without, as yet, providing an
explanation that commands general assent. Back in 1858 a
theory of causes had been put forward by Charles Darwin
and Alfred Russel Wallace. The idea had occurred to them
independently. Both had read Malthus on population (page
148). In Darwin's mind the idea formed gradually over a
long period of years; into Wallace's it flashed suddenly while
he was suffering from an attack of malaria in the East Indies.
They saw that organisms produce far more offspring than
can survive; that those offspring differ among themselves; and
that, on the average, those that chance to be the best adapted
to their environment will survive. These fittest individuals
would pass on their characters to their offspring, and thus
the race would gradually evolve. The publication of The
Origin of Species in 1859 is a landmark in the history of
biology.

Nowadays we can see that Darwin's chief service to science
was the production of a mass of evidence that evolution has
occurred. That mass of evidence has been multiplying ever
since, and the fact of evolution is not today in doubt. But
although he studied variation and wrote a large book on it,
Darwin never found out how variations are inherited. It
was Mendel who did that. It is interesting to speculate on
what would have happened if Mendel had sent a copy of his
paper to Darwin. The latter, however, died without ever
hearing of Mendel's work, and real study of the causes of

THE GROWTH OF BIOLOGICAL IDEAS 163

evolution was delayed until after the product of the monas-
tery had been brought into the light of day in 1900.

The geographic distribution of organisms, their habitats,
foods, and "enemies" seem relatively simple matters for study,
and one might have looked for the development of these
branches of biology early in the history of science. It is true
that Linnaeus and other eighteenth century biologists re-
corded the habitats of the plants they described, and Captain
Cook took biologists with him on his great voyages of explora-
tion; but no serious attempt was made to draw general con-
clusions or to found a special branch of biology covering the
natural conditions of life of plants and animals. It was not
until 1858 that an ornithologist, P. L. Sclater, made an at-
tempt to divide the world into zoological regions. The theory
of evolution then gave an impetus to such studies. It was
necessary to find not only what organisms lived where, but
how that particular distribution had come about in the course
of geological time. In the seventies Alfred Russel Wallace,
himself a great traveler, rounded off his general contribution
to the theory of evolution by a particular study of geographic
distribution. His zoological regions, founded for the most
part on those of Sclater, have retained much of their validity
to the present day. Wallace's line, w^hich he drew with such
remarkable accuracy through the map of the East Indian
archipelago, still separates the extraordinary fauna of the
Australasian region from the animals of eastern Asia.

The study of the home life of organisms or ecology, as it
eventually came to be called, still remained in a primitive
state. Darwin himself was a first-rate ecologist, as every
reader of The Origin of Species must know. Academic biolo-
gists, however, continued to leave the subject alone, as though
mere natural history were beneath their notice. Not suffi-
cient attention was paid to the fact that plants and animals
have their particular structure and functions simply because
their ancestors lived in certain habitats, were subject to the
rigors of certain climates, fed on certain foods, and were
liable to attack by certain other organisms. It was inde-

164 THE PATH OF SCIENCE

fensible to make detailed studies o£ structure and function
while neglecting the environmental factors in response to
which the structure and function evolved, but ecology is only
now coming into its own. Old-fashioned natural history is
becoming strictly scientific. The habitats of organisms are
coming to be described not in vague terms, but in the form
of accurate numerical data for the temperature and humidity
of the atmosphere, the intensity of the visible and ultraviolet
light, and so forth. The complex interrelations of organisms
are also beinsr disentans^led. It has been shown that there
are regular cycles in the abundance and scarcity of many
species, though we do not yet understand the underlying
causes. It is very unfortunate that ecological studies have
come so late in history; for man has acted like a vandal in
destroying the natural habitats in which organisms evolved.
In Great Britain only a few small patches of virgin country
remain. Through his radical transformation of his own habi-
tat, man has disturbed that of most terrestrial organisms. He
himself has become an environmental factor in the lives of
plants and animals comparable in importance with the nat-
ural phenomena of temperature, humidity, mountain-build-
ing, and the rest. It is a pity that he did not start studying
ecology before he nearly destroyed the natural subject matter
of this branch of biology. The ecology of the future is likely
to be concerned mostly with the relationships of organisms
to the artificial environments created by man.

The grand period of biology started and ended with cyto-
logical studies. The year 1838 saw the formulation of the
cell theory. About half a century later the general principles
of chromosome behavior were known. Now, at last, a retro-
gressive movement had set in. Darwin's theory led to a con-
centration of attention on the structure of organisms with a
concomitant loss of interest in their substance and functions.
People who could have been continuing the scientific study
of organisms were indulging in speculation and drawing dia-
grams from their imagination showing ho^v one group of
organisms had been derived from another. A book was writ-

THE GROWTH OF BIOLOGICAL IDEAS 165

ten to show that Vertebrates evolved from kino: crabs. No
limit was set to the free play of the imagination when once
the idea of evolution had been accepted. Side by side, how-
ever, with much that was valueless— and often curiously inter-
mingled with it— went a profound study of the comparative
anatomy of animals. So complete, indeed, was this study that
no problem of major importance was left for solution in the
twentieth century.

Comparative anatomy alone could not provide insight into
the causes of evolution. Help came at last from quite an
unexpected quarter. It was the rediscovery of Mendelism in
1900 that eventually gave the necessary impetus to studies of
evolution. It gradually became apparent that the survival of
organisms in the struggle for existence might depend on what
Mendelian genes they possessed. Those individuals that had
genes determining characters favorable to survival would be
automatically selected; the rest would perish and leave few
or no offspring. It was seen that in any species a very large
set of possible combinations of different genes was available,
and on these combinations "natural" or automatic selection
would operate: there would be survival of the individuals
with the fittest genes. But this was not all; it was found that
the genes themselves sometimes undergo sudden changes.
The cause of this process of mutation is not understood, but
it certainly results in the production of new genes; and these
behave according to Mendel's rules, generation after genera-
tion, until mutation occurs again. Mutation and recombina-
tion, then, are thought to provide the material on which
Darwin's natural selection can act; but our ideas on the causes
of evolution must remain hypothetical until we can demon-
strate unequivocally the selection of favorable genes under
natural conditions of existence.

Although we do not know the causes of natural mutation
and are, thus, still ignorant of the real cause of evolution,
quite a lot is kno^vn about how mutation can be made to
occur artificially in the laboratory. In 1927 H. J. MuUer, at
the University of Texas, discovered that the rate of muta-

166 THE PATH OF SCIENCE

tion can be enormously increased by subjecting organisms to
x-rays; and ultraviolet light and radium have since then been
shown to act in the same way. These agencies act on the
chromosomes of the germ cells. We may look for great ad-
vances in this line when someone has discovered how to con-
trol the process. At present it is a hit-or-miss affair; there
is no known way of producing one ne^v gene rather than
another.

It is strange to recall that the controversy on spontaneous
generation was only laid to rest in the middle of the nine-
teenth century. We have already seen (page 149) that Spal-
lanzani had disproved spontaneous generation by careful ex-
periments in the sixties of the century before, but people
were not easily convinced. The great Swedish chemist Ber-
zelius (page 121) still believed in the spontaneous generation
of some of the lower animals at the beginning of the nine-
teenth century; so, later still, did that restless genius of physi-
ology and marine zoology, Johannes Miiller. The most
ardent supporter of spontaneous generation, however, was
the Rouen professor Felix Pouchet, who thought that the
fermentation of decaying substances was actually the process
by which the micro-organisms found in such substances orig-
inate. This cart-before-the-horse opinion was opposed by
Louis Pasteur, whose critical experiments finally convinced
the scientific world in 1861.

Pasteur went straight on to the study of micro-organisms as
the causes of disease. In 1835 an Italian amateur microscop-
ist, Agostino Bassi, had shown that a disease of silkworms was
caused by a microscopic fungus. Not much attention had
been attracted by this discovery; and now, strangely enough,
Pasteur started his investigation of germs by studying another
disease of the same insect. Things moved quickly in the six-
ties. Another Frenchman, Casimir Davaine, discovered bac-
teria in the blood of animals suffering from anthrax and
showed that one-millionth of a drop of infected blood was
sufficient to carry the disease into a previously healthy indi-
vidual. Pasteur's final proof that micro-organisms are not

THE GROWTH OF BIOLOGICAL IDEAS 167

spontaneously generated but arise only from pre-existing
micro-organisms naturally had a profound influence on the
development of bacteriology; for it was at last obvious that
exclusion of the germ meant exclusion of the disease. Early
in the seventies a German investigator, C. J. Eberth, per-
formed the experiment that linked Davaine's with Pasteur's.
He filtered the deadly blood of animals suffering from an-
thrax and showed that the filtrate ^vas innocuous. There was
nothing in the filtered blood that could multiply and cause
disease, and the germs could not be generated spontaneously.
Bacteriology now made rapid strides, thanks largely to ad-
vances in technique. Robert Koch introduced valuable
methods for making bacteria readily visible under the micro-
scope by staining them, and he also discovered how to grow
them outside the body on jelly in glass vessels, a technique
that is still in use today.

Microscopists now looked confidently for the germs of the
most diverse diseases; but their confidence was misplaced.
It was soon discovered that some diseases could be artificially
transmitted from one animal to another, as are diseases caused
by germs, despite the fact that no sign of any micro-organism
could be detected under the microscope. Pasteur considered
that such diseases must be caused by micro-organisms too
small for the microscope to resolve. Diseases of this kind
were found to occur also in plants. And now, in the last
decade of the century, Eberth's filtration experiment was
found not to be universally valid. It was shown that the juice
of a tobacco plant infected with mosaic disease would cause
the same disease in previously healthy plants even if the juice
were filtered. Something had been discovered that could
only be observed through its effects on organisms; this some-
thing had the power of self-multiplication but, unlike ordi-
nary germs, could pass through a filter. This was the starting
point of our knowledge of the filter-passing viruses, which
are the cause of so many diseases of man, such as smallpox,
chicken pox, measles, German measles, influenza, and com-
mon colds.

168 THE PATH OF SCIENCE

Soon after the turn of the century it was found by P. Rem-
linger in Constantinople that the virus of rabies will pass
through one filter but not through another. This gave the
clue that made it possible to estimate the size of virus par-
ticles, although the microscope could not reveal them. Ex-
traordinarily fine filters were made, in which the size of the
holes, though ultramicroscopic, could be determined indi-
rectly. In the twenties virus particles were already known
to be minute. The virus of foot-and-mouth disease is particu-
larly small, not many times larger, in fact, than certain large
molecules, such as the molecule of hemoglobin. A compli-
cated building cannot be constructed from a few bricks, and
it is clear that the viruses must be extremely simple in struc-
ture: they seem to stand halfway between living and non-
living matter. We cannot regard them, however, as the
forms in which life first appeared on this planet, for they
seem remarkably dependent on the living cells of organisms,
and they do not multiply in profusion outside the body as
bacteria do. The invention of the electron microscope is
already beginning to help in the elucidation of the nature
of viruses. The resolving power of this new instrument with
suitable objects is much higher than that of the ordinary light
microscope, and actual micrographs of virus particles have
been obtained.

Again and again in the history of science we see new devel-
opments foreshadowed in old writings. In 1656 the London
physician Thomas Wharton had claimed that the secretion of
the pineal gland, in the brain, passed into the blood stream;
but no one followed up this idea. It had only recently been
discovered that glands have ducts, and the contrary idea—
that some of them have not— was unattractive. It was not
until the nineteenth century that people began to understand
how hormones or chemical messengers originate in ductless
glands, pass into the blood stream, and exert powerful in-
fluences on the action or growth of distant parts of the body.
In our own times it has been discovered that plants too have
their hormones.

THE GROWTH OF BIOLOGICAL IDEAS 169

From the thirties of the nineteenth century onward, thanks
largely to the work of the great German chemist Justus von
Liebig, proteins, fats, carbohydrates, salts, and water were
recognized as the main nutritional requirements of man and
other animals. So firmly did this idea take root that great
independence of mind was necessary in anyone who would
doubt it. Yet a Dutchman, G. Grijns, working inconspicu-
ously in the East Indies, did dare to doubt it; he even claimed
that men became ill and died just because proteins, fats, carbo-
hydrates, salts, and water were not enough. That was at the
very beginning of the present century, and not long afterward
the great Cambridge biochemist Sir Frederick Hopkins set
the study of vitamins on its feet by critical feeding experi-
ments on animals.

We left the grand problem of respiration on page 153 with
Spallanzani's discovery that the reaction of combustible sub-
stances with oxygen occurs not in the lungs, as Lavoisier
thought, but in the various tissues of the body. This was not
definitely proved until the eighteen thirties, and at that time
it was still thought that the oxygen traveled from the lungs
to the tissues in simple solution in the water of the blood. In
the fifties people began to think that it must travel in loose
combination with some unknown substance. Today it seems
difficult to believe that it was not until the eighteen sixties
that this substance was shown to be hemoglobin, the familiar
red coloring matter of blood. The discovery was largely due
to the investigations of the great German biochemist F.
Hoppe-Seyler. Everything seemed straightforward. The
oxygen in the air of the lungs combined with the hemoglobin
in the red blood corpuscles and was carried in this combined
form to the tissues; it then escaped from combination, dif-
fused out of the blood into the cells, and there combined
with carbon and hydrogen to form carbon dioxide and water.
The energy produced by this combustion was the energy
necessary for life.

The form in which oxygen travels in the blood stream had,
indeed, been discovered, but the manifold complications of

170 THE PATH OF SCIENCE

its behavior when it gets to the tissues had not even been
glimpsed. In the eighteen eighties C. A. MacMunn brought
for^vard evidence that the tissues themselves, apart from the
blood, contain substances resembling hemoglobin. These he
named histohaematin and myohaematin. The great Hoppe-
Seyler said that MacMunn's substances were simply decom-
position products of the hemoglobin of the blood. MacMunn
defended himself: he had shown in his very first paper that
his substances were present in the tissues of insects, which
have no hemoo^lobin in their blood. This miQ;ht have seemed
conclusive, but Hoppe-Seyler refused to consider the evidence
from insects. He simply printed a note alongside MacMunn's
last paper saying that he considered all further discussion of
the subject superfluous. People accepted his opinion, and
little more was heard of histohaematin, myohaematin, or
MacMunn.

It was not until the twenties of the present century that
D. Keilin of Cambridge showed that MacMunn had been
right and Hoppe-Seyler wrong. It would appear that
throughout the plant and animal kingdoms every cell that
gets its energy by the ordinary process of combustion con-
tains MacMunn's substances (or cytochrome, to use Keilin's
word). MacMunn had really been studying something far
more fundamental than Hoppe-Seyler. The latter was inter-
ested in the vehicle by which oxygen is transported to the
tissues in certain animals; MacMunn, on the contrary, was
on the verge of discovering what happens to oxygen when it
actually gets to cells, whether by Hoppe-Seyler's vehicle or
not. We realize nowadays that cell respiration is a matter
of enormous complexity. The oxygen by no means simply
diffuses into cells and combines with combustible substances.
It first combines with cytochrome and is then handed on by
this cellular respiratory pigment to combine with the hydro-
gen of combustible substances, each stage of the process being
made possible by the presence of particular intracellular fer-
ments. Knowledge of the processes of cellular respiration is
growing rapidly. It is strange to think that if MacMunn had

THE GROWTH OF BIOLOGICAL IDEAS 171

not been crushed by Hoppe-Seyler, we should probably have
had this knowledge nearly forty years sooner. A useful lesson
can be learned from the sad story: under no circumstances
must research be controlled by authority. It is true that
Hoppe-Seyler had no legal authority, such as one scientist has
over another in a totalitarian state; yet his influence was suf-
ficient to retard by several decades the investigation of one
of the most fundamental problems of life.

One cannot guess what branches of biology' are going to
develop most rapidly in the future, though one can surmise
that certain lines have been rather thoroughly ^vorked out
and offer poor prospects. Much may be expected from the
full incorporation of physiology into biology. In the past
animal physiology has been a sort of ancillary branch of medi-
cine, as botany was of pharmacology^ in the sixteenth century.
Plant physiology has never suffered under the same disadvan-
tages; it has developed naturally like the other branches of
botany and in concert with them, and is universally regarded
as a branch of botany. Zoology, greatly to its detriment, ^vas
for lono: resrarded as being^ concerned with all branches of
knowledge of animals except that of function. This idea was
as detrimental to physiology as to the major subject. A
change of outlook is at last manifesting itself. Physiologists
have begun to untie the strings that have bound them to
man, guinea pig, and frog.

If physiology can break loose from subservience to medi-
cine and stand on its own legs, we may look for rapid progress
in our understanding of the processes of growth and differ-
entiation. These are tw^o of the most fundamental phenom-
ena of life. Until now they have been studied mostly by
biologists lacking special training in physiology, for profes-
sional physiologists have held aloof. Wilhelm Roux, son of
a fencinor instructor, founded the science of the mechanics of
development toward the end of the nineteenth century. The
embryological experiments carried out by the philosophic
Hans Driesch about the turn of the century led him to con-
clude that a purely mechanical and chemical explanation of

172 THE PATH OF SCIENCE

development was impossible. Then, in the early part of the
present century, Hans Spemann of Freiburg was able to local-
ize in early embryos the actual substances that "organize" its
further development. And W. Vogt of Munich, by marking
spots with stains on the surface of living embryos, has watched
and recorded the complex movements of cells during differ-
entiation. These men and others have made real progress in
investigating the causes that transform a simple egg into a
complex adult body, the old problem that Wolff started to
attack nearly two centuries ago. This surely should be a very
attractive problem for present-day physiologists, but it is only
one among many that await solution by a fully integrated
science of biology, in which animal physiology will take its
natural place.

Chapter VIII

THE PRODUCTION OF SCIENTIFIC

KNOWLEDGE

We have followed the growth of scientific research from its
beginning in the seventeenth century, when the investigators
were amateurs engaged primarily in other pursuits but in-
spired by interest to experiment in the field of natural philos-
ophy. As their knowledge grew, they found a natural home
in the universities as professors of natural philosophy. Their
welcome in the universities arose from the fact that in the
Middle Ages the study of natural phenomena was considered
suitable for ecclesiastics, w^ho regarded the knowledge that
they derived from their inquiries as a means of developing
the fullness of the reliofious belief both of themselves and of
those whom they taught, and who felt that the revelation of
the marvels of nature was a fitting part of worship. These
ecclesiastics not only studied in their retreats but also taught
the more intelligent young men of the day, so that the uni-
versities evolved from the institutions of the church.

When the methods of experimental science were developed,
the readiness of the universities to accept the responsibility
for the advancement of knowledge was due essentially to the
fact that the results obtained w^ere immediately applicable
to the purpose of teaching. Indeed, only by assiduous effort
and discovery could the facts of natural philosophy be suffi-
ciently correlated to make it possible to present them in an
orderly manner so that they could be understood by the im-
mature minds with which a university has to deal. This need
for investigation by the teacher was so marked and the success
of teachers who w^ere engaged in experimental study was so

pronounced that it was generally recognized that the best ad-

173

174 THE PATH OF SCIENCE

vanced training in science could be obtained only under a
man who was himself actively engaged in promoting the
science that he taught. Through the nineteenth century,
the advancement of science was a function of the work of the
universities.

Toward the end of the nineteenth century, the impact of
science upon the social life of the western world became evi-
dent. Lecturers and writers, such as Tyndall and Huxley,
were pointing out to the public that the advances which were
occurring in the scale of living arose from the growing knowl-
edge of natural science. And H. G. Wells had a considerable
influence upon public thought when he published in 1902 his
book entitled Anticipations of the Reaction of Mechanical
and Scientific Progress upon Human Life and Thought.* In
this book Wells attempted to analyze the trends of invention
and development apparent at the beginning of the twentieth
century and to foresee how those new developments might
react on the structure of society. It is an excellent book, and,
looked at forty years later, it is astonishingly accurate, sug-
gesting that an anticipation of the general course of events
over a limited period is not at all impossible, though quite
obviously there will be a considerable distortion of the time
scale for the different phenomena. Wells, for example, seri-
ously underestimated the rate of development of aircraft. On
the other hand, he overestimated apparently the development
and influence of the technically trained men.

In the nineteenth century there arose a number of technical
industries that depended primarily upon discoveries and in-
ventions made by some individual or group who developed
their original discoveries into an industrial process. The
history of many industries is that they were originated and
developed by a man of genius fully acquainted with the prac-
tice of the industry and with such theory as was then known;
that his successors failed to keep up with the progress of the
industry and with the theory of the cognate sciences; and

* London, Chapman and Hall, Ltd., 1902.

THE PRODUCTION OF SCIENTIFIC KNOWLEDGE 175

that sooner or later some other genius working on the subject
advanced the available knowledge and gave a new spurt to
the development of that industry. Thus, in the early days of
the technical industries, the development of new processes
and methods was often dependent upon some one man, some-
times the owner of the firm which exploited his discoveries.
But with the increasing complexity of industry and the paral-
lel increase in the amount of technical and scientific informa-
tion, necessitating increasing specialization, the work of in-
vestigation and development, ^vhich had been performed by
an individual, was delegated to a special department of the
organization, from which arose the modern industrial research
laboratories.

The organization of research sections in industry first be-
came of importance in the dye industry in Germany. After
the initial discovery of the synthetic dyes by Perkin in Eng-
land, Hofmann and his students made large numbers of dyes
from the oils separated from coal tar, and the students of Hof-
mann founded manufacturing companies to make the dyes.
In this industry, continual research was essential, and very
soon gi'oups of chemists were producing a stream of new
processes and products, all of them protected as completely
as possible by patents. The success of this organization and
the expansion of the dye works until they controlled the
chemical industry of Germany and a great part of the world
inspired others to follow their example.

Certain other industries were founded by scientific men
who had made discoveries, and these also engaged in scien-
tific research on a large scale. Research was organized from
the very beginning in the telephone companies that Alex-
ander Bell founded, and Elihu Thomson brought the same
system into the General Electric Company when it was
formed. Soon after the beginning of the twentieth century,
therefore, industrial research was firmly established in the
German chemical and electrical industries, in the American
electrical industry, and, to a small extent, in the British and
American chemical industries.

176 THE PATH OF SCIENCE

The prototype of another kind of organization for the ap-
plication of science to industry is the Mellon Institute of the
University of Pittsburgh. Laboratories of the type of the
Mellon Institute may perhaps be distinguished as technologi-
cal research institutes, since their work is primarily in tech-
nology rather than in pure science.*

At the end of the nineteenth century, the governments of
the world started to support a limited amount of scientific
research. The oldest government-supported research is that
of the observatories, of which the first was Greenwich Ob-
servatory, founded in 1675 and supported on a very parsi-
monious scale by the British government ever since, the head
of the institution enjoying the title of Astronomer Royal.
During the nineteenth century the federal government of the
United States created the Coast and Geodetic Survey, the
Naval Observatory, the Department of Agriculture, and the
Geological Survey. On the whole, these institutions ^vere
devoted primarily to the application of science, although the
Bureau of Standards, founded in 1901, and the British Na-
tional Physical Laboratory, founded in 1899, like the Reichs-
anstalt, organized by the German government after the
Franco-Prussian War, carry out much basic research in
physics in addition to their primary task of maintaining the
physical standards used in commerce and industry.

At the beginning of the twentieth century, a new factor
entered the field of pure science. This was the creation of
two privately endowed institutions— the Carnegie Institution
in Washington and the Rockefeller Institute. From the for-
tunes that supplied the funds for them came also the Rocke-
feller Foundation and the Carnegie Corporation. The great
sums available from these sources, no less than the wise judg-
ment of those who administered the sums, have enabled them
to make the greatest contributions to the progress of science
not only in America but also throughout the world. The
Carnegie Institution, particularly, originated a new type of

* Chapter IX, p. 214.

THE PRODUCTION OF SCIENTIFIC KNOWLEDGE 177

scientific laboratory. The Geophysical Laboratory and the
Mount Wilson Observatory are of the convergent type, in
which the work of many scientists specializing in diverse fields
of science can be concentrated upon certain groups of prob-
lems. Such laboratories, which are discussed later under the
name of research institutes^ are likely to be most powerful
agencies for the production of scientific knowledge in the
future.

One of the most important factors in the organization of
scientific research at the present time is the increasing com-
plexity and elaboration of the apparatus used not only in
applied science but even in pure science. Research in pure
physics in the nineteenth century required a very minimum
of equipment, and substantial increases in knowledge were
made by workers in small laboratories who spent only a very
small sum on apparatus and constructed much of that ap-
paratus with their own hands or with the assistance of a lab-
oratory mechanic. Today the apparatus required for physical
research is of the most complex type and requires a great
expenditure of money and very well-equipped machine shops.
The nuclear physicist, for example, has progressed from the
simple apparatus used by J. J. Thomson, Aston, and Ruther-
ford to the cyclotrons invented by Lawrence, of which the
largest has cost well over $1,000,000. The cryogenic labora-
tries, which make large quantities of liquid hydrogen and
helium for research at low temperatures, are necessary for
much physical research, and the physical phenomena ex-
hibited by the stars are studied with the aid of telescopic
equipment involving capital expenditures of millions of
dollars.

Again, the identification of coincidences in the frequency
differences between spectral lines, which enables the lines to
be assigned to different systems in an element, is an extremely
laborious operation when performed by hand, and progress
in this field of physics was very slow until instruments were
designed by which these frequency differences could be ana-
lyzed automatically. As a result, the very complicated spectra

178 THE PATH OF SCIENCE

of a number of the elements have been analyzed ^vithin a
few years.

In chemistry, the simple laboratories used for analytical
work and for the early research in organic chemistry are no
longer sufficient for progress in many fields. Work on gas
reactions requires very complex equipment. Much chemical
work is done at high pressures and much at very high tem-
peratures, and more and more these methods of producing
and studying chemical reactions are of importance. Silicate
chemistry has involved a complex technology of furnace work.

In certain fields of work, a whole laboratory may be con-
sidered a tool. In the advancement of physiology, for in-
stance, a requisite is a synthetic organic laboratory that can
prepare the many compounds required. And now it seems
likely that physiological research will require a supply of
chemicals made with isotopes of the elements or with radio-
active isotopes prepared synthetically in the laboratories of
nuclear physics.

During a recent discussion of the co-operation that might
be effected between industrial research laboratories and the
investigators who were studying medicine, it ^vas suggested
that what was really required by the medical men ^vas not co-
operation but a supply of synthetic chemicals for which they
did not have to pay. Experimenters in medicine, as in physi-
ology, require a very large number of synthetic chemicals, the
cost of which is far greater than can be met from the usual
scanty budget of the investigator. What is needed is a philan-
thropic organic chemist to make the chemicals that are re-
quired; and if progress is to be made in medicine and physi-
ology, this demand must be met. Perhaps one of the most
useful things that a philanthropist could do at the present
time would be to endow a synthetic organic laboratory to
prepare chemicals for use in the medical sciences.

Another tool absolutely necessary in physiological chem-
istry is the animal colony, and for this to be really effective it
will be distinctly expensive both in first cost and in opera-
tion. Colonies of selected animals kept under very uniform

THE PRODUCTION OF SCIENTIFIC KNOWLEDGE 179

conditions and supplied widi analytically controlled food
must be established, and these require much attention and
care if the experiments are not to be interrupted by acci-
dental losses from disease. It is necessary, in fact, for us to
pay more attention to the health of our experimental animals
than we do to our own health. Similar colonies are required
for the study of heredity.

The mere accumulation of facts is being expedited very
much by improved apparatus. In the study of photography,
for instance, much of the fundamental information is ob-
tained in the form of a curve known as the characteristic
curve, which relates the density of a developed image to the
exposure given to the light-sensitive material. To obtain
these curves, the material is exposed to a series of light in-
tensities and developed, and then the densities resulting are
measured and the curve plotted. With a visual instrument,
the measurement of density is a very slow operation, and
much effort is required to produce twenty curves in a day.
Indeed, such a rate of production cannot be maintained; the
making of some four hundred photometric matches in a day
is very tiring. Today automatic instruments using photo-
electric cells measure the densities and draw the curves, and
it is well within the capacity of such an instrument to produce
over a thousand curves in a day when used by an unskilled
operator. More and more, scientific men are designing im-
proved methods of collecting and analyzing the data on which
they can base their studies. Thus they are again accelerating
our production of knowledge.

A useful classification of research laboratories in general
is based on consideration of whether all the problems investi-
gated are connected with one common subject or are of many
kinds having no connecting bond of interest. The first type
of laboratory might be called unipurpose or convergent and
the second, multipurpose or divergent.

In the convergent laboratories, although the actual investi-
gations may cover as great a range of science as those under-
taken in a divergent laboratory, all the investigations are

180 THE PATH OF SCIENCE

directed toward a common end, that is, toward the elucidation
of associated problems related to one subject. Thus the staff
of the Geophysical Laboratory of the Carnegie Institution,
which includes physicists, geologists, crystallographers, min-
eralogists, and chemists, works on the structure of the rocks
and their manner of formation. Although the field of the
actual investigations ranges from high-temperature photom-
etry to the study of complex solubility diagrams and their
interpretation on thermodynamical principles, the results of
all the work carried out are converged on the problem of the
structure and formation of the earth's crust. The Nela Park
Laboratory of the General Electric Company, in the same
way, is studying the production, distribution, and measure-
ment of illumination; and all its work, which may involve
psychology, physiology, physics, and chemistry, is related to
that one subject.

A laboratory of the convergent type, which carries on work
in one field of science for a considerable time, may conveni-
ently be described as a research institute. Research institutes
have come into existence in the last half century without our
realizing that they represent an innovation in the organiza-
tion of research, but they will probably be the most important
agencies for the production of scientific knowledge in the
future. In many cases they have been formed by outstanding
investigators at universities. A professor specializes in some
field of work and directs the studies of his graduate students
into that field. Then others who are interested are attracted
to join him until his laboratory is recognized as the natural
center for researches on that subject.

Many examples of this process could be given, from which
I can take, almost at random, only a few as illustrations. The
invention of the cyclotron has made the radiation laboratory
at the University of California the central point of the world
for research in nuclear physics. At Cambridge University
in England, the Cavendish Laboratory has been an institute
of physical research under two successive directors, J. J.
Thomson, who determined the nature of the electron, and

THE PRODUCTION OF SCIENTIFIC KNOWLEDGE 181

Sir Ernest Rutherford, who established the foundations of
radioactivity. Under men such as tliese, ahnost all the ^vork
carried on in the laboratory has been concentrated on the
subject in which they themselves were working; and instead
of teaching general physics, the laboratory is a most valuable
and effective research institute. Kamerlingh Onnes estab-
lished at Leyden a laboratory for research at very low tem-
peratures, where he investigated the superconductivity of
metals and the extraordinary properties of liquid helium.
Peter Kapitza was so original in his ideas for the study of the
physics of very high magnetic fields that the Royal Society
fathered for him a special laboratory at Cambridge, and
Kapitza is now carrying out similar work in the Soviet Union.
In different fields of scientific work, Harlow Shapley at Har-
vard is concentrating the work of a group upon the proper-
ties of the meta-galaxy, and T. H. Morgan in his laboratory
at the California Institute of Technology has concentrated
on the problems of genetics, especially as exemplified in the
Drosophila fly (Chapter VII, page 160).

In all these cases, the interest and capacity of a university
teacher have supplied the incentive for the organization of a
research institute as part of the university structure. Unfor-
tunately, such institutes often languish and die when the
teacher himself passes; only rarely can the university find a
successor who will justify the continuance of the specialized
work. Greater stability is attained when such institutes have
been founded deliberately by philanthropic foundations who
desired to expend money on the advancement of scientific
knowledge. With the present trend toward the use of more
and more complicated and expensive apparatus and toward
greater specialization in the methods used in investigation,
research institutes are becoming more and more necessary for
the advancement of knowledge in the future.

At this point it may be well to summarize the various
agencies available for the production of scientific knowledge.
The basic institution on w^hich everything else depends is the
scientific department of the university, and this differs from

182 THE PATH OF SCIENCE

all other institutions in that it has and should have no direc-
tion from outside and complete freedom in its choice of sub-
ject. It is from the universities that the bulk of the new ideas
by which science is advanced are likely to come, since in all
other institutions there is some restriction and will probably
always be some restriction in the fields selected for work.
The application of science is dealt with primarily in the re-
search laboratories of industry, in the endowed technological
institutes, and in the laboratories operated through govern-
ment departments, which are increasing very rapidly in size
and complexity. The more complicated fields of science re-
quire for their exploitation research institutes, each of which
deals with a limited field of science and is recognized as a
center for the advancement of knowledge in that field.

Research institutes will not relieve the universities of their
responsibilities for teaching and for conducting scientific re-
search; indeed, the activity of the universities in the prosecu-
tion of research may be expected to increase. Whereas the
fundamental business of a university is to teach, the argument
for research has been that teaching is impossible unless the
knowledge is available and that those engaged in the produc-
tion of knowledge are the best teachers of it. This is un-
doubtedly true within limits, and it is probable that a research
institute is the best training place for a research student.
Certainly the giaduates from the Cavendish Laboratory
would justify the policy of its directors, and a student who
had worked under Ramsay would be the first to insist that
the eager pursuit of knowledge in that ill-equipped labora-
tory at University College, London, was a inost stimulating
atmosphere in which to acquire the methods and habit of
research. But for the student who wants a general kno^vl-
edge of the subject and does not propose to devote himself
to research, a too specialized university laboratory has its
disadvantages. Moreover, the universities are finding it in-
creasingly difficult to supply the equipment required for re-
search. In the past, the enthusiasm of the investigator, the
availability of sympathetic wealthy individuals, and, by no

THE PRODUCTION OF SCIENTIFIC KNOWLEDGE 183

means least, the great philanthropic foundations have, in the
end, provided the funds, but at a great sacrifice of time and
effort by scientific men.

To a certain extent, the industrial research laboratories
will undertake responsibility for special fields of work. The
Kodak Research Laboratories in Rochester are, indeed, a
research institute devoted to the study of photography (Chap-
ter IX, page 208). But industrial laboratories are funda-
mentally intended to deal ^vith the application of science
rather than with the creation of new knowledge, and it is
almost certain that they cannot be expected to provide ade-
quately for the advancement of science on all fronts.

Public taxation is a very important source of the funds
needed for the support of scientific research at the present
time and one likely to supply the greater part of those funds
in the future. In Soviet Russia, with its planned economy,
the government has already organized its scientific ^vork in
a great group of research institutes distributed throughout
the land and controlled, in the last instance, by the members
of the Academy of Sciences.* The Academy was founded by
Peter the Great. Formerly, its headquarters were in Lenin-
grad, but they have been transferred to Moscow. There are
about ninety academicians. In general, each group of in-
stitutes is operated by a special committee wIiost^ chairman
is one of the members of the Academy. Thus, in agricultural
science. Professor T. D. Lysenko of the Academy is the presi-
dent of the Academy of Agiicultural Science, which includes
altogether thirty members of the Academy of Sciences. Under
this operating committee there are throtighout the Soviet
Union over three hundred institutes of various sizes contain-
ing, as a whole, about ten thousand scientists and, in addi-
tion, about eight thousand general assistants, field, and labora-
tory workers. The administrative control of the system is
operated separately from the direction of the scientific work.

* J. G. Crowther, Soviet Science, London, Kegan Paul, Trench,
Trubner & Co., Ltd., 1936.

184 THE PATH OF SCIENCE

Similar groups of institutes exist in Russia in all fields of
science. A very large organization deals with physics, which
is chiefly supported through a division of the government com-
missariat of heavy industry known as the Scientific Research
Sector. Institutes operated by it include the Physico-Techni-
cal Institute in Leningrad, directed by Professor Joffe; the
Institute of Chemical Physics in Leningrad; the Optical In-
stitute of Leningrad; the Karpov Institute of Physical Chem-
istry in Moscow; and the Physico-Technical Institute of
Kharkov. That in Russia, as elsewhere, institutes are de-
veloped to suit the idiosyncrasies of individual scientists is
shown by the example of the Institute of Physical Problems.*
This institute was organized by Kapitza in 1937 under the
control of the Academy to study problems of theoretical
physics, especially those relating to the use of low tempera-
tures and strong magnetic fields. In his account of its or-
ganization, Kapitza einphasizes his use of a relatively small
staff and his practice of following personally the work in the
laboratory.

The elaborate organization of science that has developed
in the Soviet Union is, of course, of the same pattern as other
developments in that country. It is an organized and planned
system erected to perform a specific function, and to only a
small extent is it the result of organic growth over a number
of years.f

The recent proposals put forward by Dr. Vannevar Bush,
director of the Office of Scientific Research and Development,
in his report to the President of the United States entitled

* A very interesting report on the work of this institute by P. L.
Kapitza is published in English in Voks Bulletin, No. 9-10, 22 (1943).

■j- A number of British and American scientists visited Russia on the
occasion of the two hundredth anniversary of the founding of the
Academy of Sciences. Their reports on the scientific work done there
(Nature, Sept. 8 and Sept. 15, 1945) show that the actual conduct of
work by no means corresponds to the regimented organization suggested
in earlier accounts of the system. If we may judge by these reports, the
Russian scientific workers control their own work and choose their own
problems very much as is done in other countries.

THE PRODUCTION OF SCIENTIFIC KNOWLEDGE 185

Science^ the Endless Frontier, include a new organization for
the production of scientific knowledge in the United States.
It is to be known as the National Research Foundation. It is
intended to make available a considerable amount of money
estimated to start at $33,500,000 and to reach §122,500,000 in
five years, these sums to be supplied by the federal govern-
ment from taxation. It is not proposed that the Research
Foundation should build, own, or operate laboratories. In-
stead, continuing the practice of the Office of Scientific Re-
search and Development through the war, programs will
be organized and supported in existing laboratories and
especially in the universities, and funds will be available for
assisting in the training of research workers and in the sup-
port of publication. This wide proposal has not yet been
implemented by legislation, so that it is too early to judge its
effect upon the future organization of scientific research in
the United States. The effect should, of course, be very bene-
ficial though there is certainly some danger that the support
of scientific research in the universities by an external body
might limit the freedom of choice of subject. No doubt this
danger will be recognized by the members of the Foundation,
and they will do their utmost to guard against it. Neverthe-
less, the history of science is full of cases where the interests
of some scientific worker have been so opposed to the general
trend of thought at the time that it would have been quite
impossible for him to obtain support for his ideas, and he
has been subject to active opposition and ridicule (Chapter
VII, page 170).

The most important advances in science will continue to
be unexpected, improbable, and even unpalatable, and it is
essential that the men who are to make them should not be
prevented from doing so. In consideration of this matter, it
must not, however, be forgotten that universities at the pres-
ent time are tending more and more to embark upon indus-
trial research in co-operation with industry, much of this
so-called research being really development work of a type
calling for energy and inventive ability rather than for scien-

186 THE PATH OF SCIENCE

tific imagination. This is likely to be far more disastrous
to the free spirit of inquiry in the university than the receipt
of support from such an organization as the National Re-
search Foundation.

In Great Britain, as in the United States, the public and
the government have been impressed by the great importance
of the work done by the scientific men for the prosecution of
the war and are considering actively the possibilities of in-
creasing scientific work by the supply of public funds, w^hose
source lies eventually in taxes. There appear to be no pro-
posals in Great Britain for the establishment of research in-
stitutes. It is proposed instead to aid the universities and to
construct one or more technological institutes of the type of
the Mellon Institute, w^hile every effort will be made to en-
courage research in the laboratories owned by industry and,
especially, under the direction of the Research Associations,
which are a feature of the organization of research in Great
Britain.

In the widespread discussion of scientific research pub-
lished during recent years, there is little material relating to
the actual organization of research laboratories and institutes.
It has generally been assumed, in fact, that their organization
would be similar to that of a factory or an army. Thus, in
1920, the author of this book wrote: *

There are tw^o forms of organization. In the depart-
mental system the organization is that familiar to most
businesses. The work of the laboratory is classified into
several departments; physics, chemistry, engineering, and
so on, according to the number necessary to cover the field,
and each of these departments has a man of suitable scien-
tific attainments in charge. In a large department each of
these men will in turn have assistants responsible for sec-
tions of the department, all the heads of departments finally
being responsible to the director of the laboratory.

Under the alternative or cell system the laboratory con-
sists of a number of investigators of approximately equal

* C. E. Kenneth Mees, The Organization of Industrial Scientific Re-
search, p. 81, New York, McGraw-Hill Book Co., 1920.

THE PRODUCTION OF SCIENTIFIC KNOWLEDGE 187

Standing in the laboratory, each of them responsible only
to the director, and each of them engaged upon some
specific research. Each such investigator, of course, may
be provided with assistants as may be necessary.

Each of these systems has advantages and disadvantages.
Under the departmental system, the advantages are strict
organization, good co-operation throughout the depart-
ments, a plentiful supply of assistants for the abler men
who form the heads of departments or sections of the de-
partments. The chief disad\'antage is that the system tends
to stifle initiative in the younger men. While it is true
that research men require to serve a considerable appren-
ticeship to older investigators, there comes a time when
every man wishes to try to develop his oun line of research
on his own initiative and to carry out work by himself, and
while it is quite possible to provide for such men in a de-
partmental organization, there is some danger that men
who are really capable of original work may not get the
opportunity to carry it out.

The cell system, on the other hand, provides a good ar-
rans^ement for men of orio^inal initiative and of the self-
reliant type; it enables a man to continue a single line of
work by himself for a long time and patiently to bring to
a conclusion work that in a departmental organization
might have been abandoned because of its apparently un-
remunerative character. On the other hand, the cell sys-
tem tends to exaggerate the vices of such men. They tend
to become secreti^'e, to refuse co-operation, to be even re-
sentful if their work is inquired into; ^vhile if a man who
has developed a line of work for himself in a cell leaves the
laboratory, it may be very difficult for anybody else to take
up the work, in ^vhich case a great deal of time and money
is lost, and w^ork that should have been carried forward is
left unfinished. Another objection to the cell system is
that men who are good organizers and who are of the type
that can carry on work requiring many assistants do not
easily find a place in it.

In practice, a balance between these t^vo systems of or-
ganization is essential and will develop in any laboratory.
It is not possible to work a rigid departmental system, and,
on the other hand, no cell system in its most definite forai
could be effective. The form of orsfanization ^vhich is the
easiest in administration is undoubtedly some modification
of the departmental system, since only by this means can

188 THE PATH OF SCIENCE

Students fresh from college acquire adequate training and
at the same time keep in touch with different branches of
their subject and avoid the danger of immature specializa-
tion. A laboratory should therefore be organized in de-
partments with an intradepartmental section in which a
young man who develops the ability to carry out his own
work may be able to take up work on his own initiative,
retaining his position in the department and carrying on
his work under the general supervision of the chief of his
department. There will always be a tendency in the de-
partmental organization for men to desire to split away
from the department to which they are attached and be-
come semi-independent in the laboratory, and this tendency
must be resisted in the organization and by the director of
the laboratory. At the same time, it is important that the
control should not be so rigid that men feel that they are
prevented from exercising their own initiative.

Twenty-five years later, the writer of this passage must
acknowledge that it does not correspond to the realities of
the situation. Scientific research cannot really be organized
under department leaders, who are themselves working scien-
tists carrying out research w^ork. The fact is that the unit of
scientific research is a scientist ^vith a group of assistants and
he is, by definition, capable of directing his own work by his
own methods. In the operation of his work, he must be inde-
pendent of all control and free to do whatever he ^vishes.
The function of his superior in the organization is not to con-
trol the operation of the work; it is to direct the work toward
the problems that seem most desirable, to insure and assist
co-operation between the individual research units, to pro-
vide the necessary working conditions and environment, and,
in an industrial laboratory, to see that any results obtained
are applied in practice. This cannot be done by a man ^vho
is himself interested in his own scientific w^ork since he ^vill
inevitably devote himself to research on certain problems,
using some members of the department as assistants and leav-
ing the rest of the department without control. This state-
ment can easily be challenged by those who have observed
the successful direction of university laboratories by active

THE PRODUCTION OF SCIENTIFIC KNOWLEDGE 189

scientific workers. Nevertheless, inquiry will show that even
where the laboratory and its chief have become famous, the
direction of the laboratory was weak, and success ^vas due to
the gieat skill sho^vn by the chief and those who worked di-
rectly with him in his own problems. In a university labora-
tory, the junior scientists are there for only a short time; they
are still learning the methods of research and will soon pass
on to other positions. Neglect by a chief absorbed in his own
problems can be tolerated by such men; but in an industrial
laboratory or a research institute, where men spend their
whole career, such neglect leads to much unhappiness and
frustration.* The point at issue can be understood, perhaps
from an analogy. The type of organization generally adopted
is derived from the military analogy. The department leaders
correspond to officers who give orders to their subordinates.
But the true analogy of a scientific research organization is
not an army; it is an orchestra. Each musician of an orchestra
is important and independent; the members are correlated
through the conductor, who is represented in the laboratory
by the department head or in small laboratories by the di-
rector. It is not the duty of the laboratory head to command
his scientific staff; it is his duty to lead it. Thus the military
type of organization usually adopted for industrial labora-

* P. L. Kapitza (Voks Bulletin, No. 9-10 [1943]) believes that the
director of a laboratory cannot be effective unless he works with his
own hands. He says: "Only when one works in the laboratory oneself,
with one's own hands, conducting experiments, even the most routine
parts of them,— only under these conditions can real results be achieved
in science. Good work cannot be done with other people's hands. A
person who devotes ten or twenty minutes a day in directing scientific
work can never be a great scientist. At least, I never saw or heard of
a great scientist who worked in that manner, and I do not think it can
be done. I am certain, that the very moment even the greatest scientist
stops working in the laboratory himself, he not only ceases to develop
but, in general, ceases to be a scientist." Kapitza, however, is speaking
of an institute employing only a very few scientists, and he acknowledges
that when the work expands and development work is involved, the
time of the director will be taken up with other matters than work in
the laboratory.

190

THE PATH OF SCIENCE

tories and even for research institutes, as shown in Figure 4,
does not really operate at all. Instead, the operating system
is that shown in Figure 5.

In a small laboratory, one having less than about twenty
scientific men, no department heads for research work are
necessary; the men can be responsible to the head of the

DIRECTOR

ADMINISTRATIVE
STAFF

EXECUTIVE
STAFF

ffiSSi

SCIENTISTS

Figure 4. Formal Organization Chart of a Research Laboratory.

laboratory, who is generally known as the director. Any
"service" or "development" divisions, on the other hand,
should have efficient department heads in control of them so
that the director can devote his attention to the scientific re-
search without being distracted by the demands of those to
whom the "service" is given. In a large laboratory, each
section engaged in work in a special field should be respon-
sible to a department head acting as an assistant director.
Thus the organization of a large industrial laboratory might
be represented by the chart shown in Figure 6.

The efficiency of a research laboratory depends to a very
great extent upon the director. The qualifications of the
director of a research organization are scientific ability, in-

THE PRODUCTION OF SCIEXTIFIC KNOWLEDGE 191

tegrity of character, and energetic activity. There are scien-
tists who are splendid research men and can operate with a
small group of students or assistants and obtain most success-
ful results, but who ^vould be utterly useless in a large labora-
tory. They would not have the energy to keep in touch with
the innumerable details of such a laboratory and, at the same

DEVELOPMENT
GROUPS \

SERVICE
GROUPS

S- SCIENTIST AND ASSISTANTS

Figure 5. Approximation to the Actual Organization of a Laboratory

of Medium Size.

time, to concentrate on the critical points in the research
work and lead their men rapidly to a successful conclusion in
each field of ^vork in which such a conclusion became pos-
sible. Accounts of great research leaders always refer to them
as spending time in the laboratory, discussing -matters ^vith
their staff, helping or suggesting in one field after another,
encouraging the despondent, and rejoicing ^vith the suc-
cessful.

The problems involved in finding suitable directors for
industrial research laboratories are discussed later. In lab-
oratories Avorking in pure science, the difficulties are perhaps

192

THE PATH OF SCIENCE

less, since it is not necessary to find a scientific man who is
also capable in the commercial field. Nevertheless, the suc-
cess of research institutes will depend to a large extent upon
the choice of directors. The trustees of such institutes must
find suitable directors for the institutes and then apply the

DEVELOPMENT
GROUP

SERVICE GROUPS

S- SCIENTIST AND ASSISTANTS

Figure 6. Approximation to the Actual Organization of a Large Lab-
oratory.

pragmatic system to their enlargement or diminution. When
an institute director is being successful and is producing val-
uable work, his field of activity should be enlarged and the
institute given increased support. When he is doing only
moderately well, it is probably unwise to expand his field
even though he may blame insufficient support for his in-
ability to produce results. Good men will produce results
with a minimum of means, but as soon as they do so, the
further means should be supplied.

THE PRODUCTION OF SCIENTIFIC KNOWLEDGE 193

Great care must be taken in the oriQ;inal selection of the
director, since it is very difficult to remove him and his re-
moval involves a great disruption of the work of the institute.
Occasionally those responsible for the organization will realize
that they have made a mistake— that the man they have chosen
cannot do the work set before him— and then there should be
no hesitation in making a change. This may seem an easy
thing to do, but it is really very difficult. The great defect in
management of all kinds is the tendency of those in authority
to tolerate inefficiency rather than to face the unpleasant task
of removing the inefficient. It is commonly believed that
business men are harder in their dealings than public officials
or executives in other walks of life. Anyone who has had
much business experience will, however, agree, I think, that
the greatest fault of business management is a tendency in
personnel matters to avoid the issue because of weakness and
sentiment. The motto for an executive of any kind in the
treatment of those responsible to him is that he should be
tough and he should be generous. He should demand a high
standard of efficiency and endeavor to maintain it by making
any changes that seem necessary, but he should be generous
to the weaknesses of the inefficient and the misfortunes of
the unlucky. It is unlikely, of course, that these principles
for the selection and guidance of research directors will be
carried out fully by any board of direction, but I believe that
their application will be greatest if the controlling body con-
sists primarily of scientific men.

The oreat dangrer is that the institutes misrht fall victims to
a system of political jobbery and that the staff and even the
director might be appointed for other reasons than their com-
petence. This difficulty, however, would supply its own
remedy. The institute would simply fail, and the advance
of science, locally checked, would proceed elsewhere.

A problem that will arise if a considerable number of
research institutes are supported by public fimds will be the
use and application of the results obtained. This will be
complicated by the belief held by the public that a new tech-

194 THE PATH OF SCIENCE

nical development is largely accomplished when the original
discovery is made, a belief which has been encouraged by
scientists without industrial experience who believe that any
delay in the application of a scientific discovery is due to
malignancy on the part of industrialists rather than to the
inherent problems of promoting a scientific discovery to the
stage where it is of general use.

In industrial research ^ve usually consider that the cost of
the work in the research laboratory is of the order of 10 per
cent of the total cost of developing an entirely new product
to the point where it is ready for the market. Since the cost
is an accurate measure of the energy involved, it is fair to
consider that the original invention represents on the average
only 10 per cent of the work involved in the development of
a new product.

In a system of private enterprise, discoveries made in re-
search institutes are not developed commercially unless those
who develop them can see the possibility of a return for the
work they have to do. If such discoveries are offered for
development by the granting of non-exclusive patent licenses
without any possibility of even a temporary monopoly being
obtained, they will not be attractive to those who must
spend much inore money and energy than were required for
the original discovery. On the other hand, the spirit of the
time is quite opposed to the gianting of an effective monopoly
for even a moderate term of years. During the second W^orld
War, the Alien Property Custodian in the United States made
available a large number of patents confiscated from enemy
holders, but in the terms on which these patents are offered,
there was a provision for an exchange of licenses if the licen-
see holds patents in the same field. This requirement of
itself was sufficient to prevent industries from availing them-
selves of these patents to any great extent. The problems,
therefore, arising from any attempt to control the use of
discoveries and inventions of government-controlled research
institutes are very great indeed. Probably by far the best
solution would be to publish all the results, to take out no

THE PRODUCTION OF SCIENTIFIC KNOWLEDGE 195

patents, and to leave the industrial ^vorld to apply whatever
it could, obtaining its protection from the control of sub-
sidiary inventions, which almost always arise in the develop-
ment of a primary discovery.

The conclusions reached, therefore, as to the system of
scientific research likely to develop in the future may be sum-
marized as follows: The advancement of science will continue
to depend upon the universities and upon the industrial lab-
oratories, but much of the responsibility may be transferred
to institutes devoted to special branches of science, probably
supported by public funds and, it is to be hoped, controlled
eventually by the scientific academies. If such a development
comes to pass, it may be expected that science will advance
more rapidly than at the present time; that society at large
will recognize its dependence on the advance of science to a
much greater extent than it does at the present time; and that
there will be a considerable amount of insistence by both the
general public and the official world on the planning and
control of the scientific work.

There is at present much discussion of the value of plan-
ning for the promotion of scientific research, and the discus-
sion has become somewhat embittered by its relation to party
politics. The laissez-faire attitude of liberalism that per-
vaded intellectual thought in the nineteenth century is largely
displaced today by the desire for a planned economy, which
has developed from the writings of Marx, Engels, and their
successors. This change arises from several causes, but mainly
from the anxiety for the future that men feel today and from
the rising importance in the intellectual life of the world of
the engineers, to whom planning is a fundamental of life.
If you have been educated chiefly by reading Plato and
Euripides, you will have little faith in planning. If, on the
other hand, you have been educated at an engineering school
and have since spent your time in erecting buildings, mak-
ing bridges, or designing automobiles, you will have much
faith in planning. The people who dominated thought fifty
years ago had been educated as classicists; the people who

196 THE PATH OF SCIENCE

lead thought today have been educated as engineers. Which
school of thought is right? The ans^ver to this depends on
what we want to do.

We can plan for the future and then we can carry out our
plans provided that we remember the limitations of planning.
We can only plan things that we can control, and our plans
will be carried out only so long as our control is effective. We
can plan production in a factory because we can control it.
If the production is falling below our needs, we can increase
it; if it exceeds them, we can diminish it. To plan, \ve need
two things: first, the kno'^vledge of the processes that we are
attempting to control; second, the physical power to control
those processes. It is when we extend our planning from the
things that we know to the fields where our knowledge is
weak and from the things that we can control to those that
are in their nature uncontrollable that our planning fails.

When these principles are applied to the planning of scien-
tific research, we find that the kinds of research that can be
planned best are those which are least fundamental. Pro-
duction can always be planned. The last stages of develop-
ment can be planned with considerable certainty. When a
new chemical has been made in the laboratory and the yields
have been tested, a pilot plant must be built. The building
of this pilot plant and even the time which it will take to test
the processes on a moderate scale can be foreseen, and so in
chemical factories pilot plant operation is usually carried out
not as a research experiment but as a co-operative effort in-
volving both the research men who originated the process
and the production men who will operate it. Not infre-
quently the whole is under the direction of a chemical engi-
neering group who specialize in pilot plant operations.

When more basic research is considered, planning neces-
sarily becomes less certain. If ^ve have made a new chemical
in the laboratory, we know that we can make it in a pilot
plant in spite of the fact that new problems may arise. But if
the chemical has never been made or even if it has been made
but the yields are unsatisfactory, we know less certainly ho^v

THE PRODUCTION OF SCIENTIFIC KNOWLEDGE 197

much time and effort will be required to get the process ready
for a pilot plant test. Nevertheless, all applied research of
this type can be planned and, to a considerable extent, should
be planned.

W'hen, however, we go back still further and attempt to
discover an entirely new process, it is unlikely that any close
planning of the work will be of value. In practice, what is
done is to present the problem to a competent chemist and
leave him to study parallel syntheses in the literature and to
try one method after another which may lead to the result
that he requires.

The chances of making discoveries that will advance a
branch of science can be increased simply by having more
men engaged in work in that field. Much of the recent ad-
vance in the science of astronomy has come from the accumu-
lation of facts by a considerable number of observers, these
facts being published and so made available for analysis by
a limited number of skilled mathematical analysts. Many
discoveries in astronomy have been made, as is said, "by ac-
cident," but the accident could only have occurred to an
astronomer who w^as working in that field. The discovery
of the sharp absorption lines produced by the scattered mole-
cules of interstellar space, for instance, could not have been
made unless astronomers had been photographing distant
galaxies with powerful spectroscopes, and even then their
detection depended upon the use of a comparatively fine-
grained and therefore relatively insensitive photographic
plate. Scientific discoveries of a basic type result, therefore,
not from an attempt to make a given discovery but from con-
centration upon a special field of work by men using instru-
ments of sufficient power and having sufficient skill to recog-
nize the discoveries when they appear.

In the organization of scientific research, therefore, the
value of planning varies from the necessity for detailed plan-
ning by engineering experts when a discovery is to be applied
on a large scale to the most complete freedom of thought and
experiment when we do not know what to look for and have

198 THE PATH OF SCIENCE

no conception o£ what is likely to be found. As Dr. Baker
said when discussing the discovery of the x-rays:

If someone had thought it convenient to make the human
body transparent, and had allocated money for the research,
the result would have been a comprehensive plan, a team
of research workers, a very large card index, a waste of
money, and no x-rays. . . . Yon Rontgen had no thought
of trying to make human flesh transparent when he discov-
ered the penetrating powers of x-rays. He was interested
in the phenomena of electric discharge in high vacua, and
did not guess that the result of his work would be the dis-
covery that certain rays could be used in the diagnosis and
treatment of human illness.*

A most interesting discussion on the planning of scientific
research has arisen in the columns of the New York Times
following the publication of the report by Bush to the Presi-
dent of the United States. The report was criticized in an
editorial (New York Times ^ J^^ly 21, 1945) on the ground
that it does not go far enough in providing for the planning
of the work under the control of the federal government.
This editorial brought a reply from J. B. Conant, who had
through the war been the chairman of the National Defense
Research Committee. Dr. Conant's views may be summarized
by a quotation: "There is only one proved method of assist-
ing the advancement of pure science— that of picking men of
genius, backing them heavily, and leaving them to direct
themselves. There is only one proved method of getting
results in applied science— picking men of genius, backing
them heavily, and keeping their aim on the target chosen."

In wartime, targets can be chosen with a reasonable degree
of certainty and the second procedure succeeds. In pure
science, no such objective can be defined. The subject was
taken up by O. E. Buckley, president of the Bell Telephone
Laboratories,-)" who protests against the idea that industrial

* John R. Baker, The Scientific Life, p. 59, London, George Allen
and Unwin, Ltd., 1942.

f This is by far the largest research laboratory in the world, employing
over five thousand people and costing about 530,000,000 a year.

THE PRODUCTION OF SCIEXTIFIC KNOWLEDGE 199

research can be directed successfully from above. Buckley
says: "One sure way to defeat the scientific spirit is to at-
tempt to direct inquiry from above. All successful industrial
research directors know this, and have learned by experience
that one thins^ a 'director of Research' must never do is to
direct research, nor can he permit direction of research by
any supervisory board."

Buckley upholds Bush's plan, agreeing, however, that re-
search efficiency can be improved by teamwork but objecting
to the planning or "mapping out the field of science to reveal
gaps in knowledge" suggested by the New York Times.

Warren Weaver, a prominent member of the directing staff
of the National Defense Research Committee, believes that
any attempt to use the methods effective during the war
would be disastrous if employed to control scientific investi-
gation during times of peace. He believes that national sup-
port for science should sponsor every movement and develop-
ment that helps to create a favorable atinosphere for research
but should by no means set up any group to chart its course.

In an article dated September 9, 1945, W^aldemar Kaempf-
fert, a scientific editor of the New York Times, insists that
the advance of science should be accelerated by planning and
organization, contrasting this with "the inefficient laissez-faire
method of the past." He suggests that "a J. Willard Gibbs,"
who wanted to apply statistical mechanics to chemistry, might
"join the organization" and "work happily in its atmosphere."
Dr. Kaempffert says: "Whether such a man Tvorks alone or
with others, no Director in his senses would tell him ho^v he
should proceed." When we remember the history of \\^illard
Gibbs, it scarcely seems probable that if an organized research
group had existed he would have been invited to join it or
would have worked happily in its atmosphere.

W. R. Whitney, director of the great laboratory of the
General Electric Company, the prototype of all industrial
research laboratories, wrote in 1931:

There exist two widely divergent paths by which man-
kind has advanced. One is Bacon's "variation in the ef-

200 THE PATH OF SCIENCE

ficient"— doing better in some ways what has ah^eady been
done. It has become familiar to man in economics, in
^vork of general welfare, in the mere mechanics of time-
saving. The other path, extending beyond specific concep-
tions, leads to random and bold experiment— to pure re-
search, where discovery is often unexpected. The most
remarkable discoveries of the next eighty years will be of
that kind.

It is interesting that even those w^ho are most anxious to
introduce the maximum of planning into the control of scien-
tific research agree on its failure in regard to discoveries of
the greatest importance. J. D. Bernal says:

In any survey of the business of scientific research, gen-
eral lines of advance can be seen and fairly probable con-
clusions drawn from them. What cannot be seen are the
possibilities of fundamental, new discoveries and their
effect in revolutionizing the whole progress of science. The
practical problem is to see that science advances on the
^\ idest and most comprehensive front, being prepared to
accept and use as welcome gifts the radical discoveries that
come in its way.*

This is in fact, of course, the abandonment of planning.
It is these very revolutionary discoveries that make it im-
possible to plan the future of science.

When looking back, it is very easy to see how science could
have been planned. Looking forward, all we can do is to
continue to spread the frontiers of our knowledge and, as
Bernal says, "to accept and use as welcome gifts the radical
discoveries that come in our way."

Phillips f points out that since progress is made by trial
and error, and its extent is therefore proportional to the
number of trials, the conditions most favorable to progress
will be those that favor the greatest number of trials. These
conditions will be those where the number of independent
thought centers is greatest, that is, the conditions of maxi-

* J. D. Bernal, The Social Function of Science, p. 343, New York,
The Macmillan Co., 1939.

f Chapter II, page 19, footnote.

THE PRODUCTION OF SCIENTIFIC KNOWLEDGE 201

mum individual liberty. This is the true reason for the
importance of personal liberty; progress depends on liberty.
It is also the reason for the failure of any system for planning
scientific research. The increase in efficiency of operation
achieved by planning is balanced by the loss of independent
thought, -^v ith a consequent diminution in the trial of ideas.
This is especially true of the conduct of scientific research in
the universities where any restriction of the liberty of investi-
gators to choose their own ^vork or even any inducement to
follo^v lines chosen for them is to be deplored. It is even
desirable that a large number of investigators should be
forced, by lack of external suggestion, to find for themselves
subjects for their work.

Chapter IX

APPLIED SCIENCE AND INDUSTRIAL

RESEARCH

As we have seen, the apphcation of science to industry
developed first in the industries which themselves owed their
existence to the gi^owth of science, especially the chemical and
electrical industries. The value of research in producing new
materials and methods of manufacture slowly made it clear
that in every industry in which technical processes were in-
volved—and in what industries are they not involved?— organ-
ized scientific research was necessary if the industry was to
survive and flourish. The thing that convinced business men
of this was the age-old fear of competition. A man might
believe that new scientific discoveries were of no value to
him, but he could not entirely forget that his active com-
petitor might take advantage of these discoveries— might, in-
deed, even be secretly making discoveries behind his back
and might come out some day with a new line of products
that would take his business away from him.

The primary function of the research department in an
industry is to provide the scientific knowledge to meet diffi-
culties, improve processes and products, and discover and
develop new products; but in modern industry the research
department has assumed broader functions. George East-
man once said that his research laboratory ^vas "responsible
for the future of photography." On the other hand, C. C.
Paterson of the General Electric Company, Ltd., has said:
"Industrial research exists in order that industry may have
within itself those scientific resources in workers and equip-
ment which will help the industry to cultivate the scientific

outlook throughout all its personnel and activities." These

202

APPLIED SCIENCE AND INDUSTRIAL RESEARCH 203

two statements together may be taken as representing the
ideals to^^vard which every industrial research laboratory
should strive.

In the early days of industrial research, a business assigned
to it only a very small part of the executive budget. Confi-
dence in the attainment of valuable results was small. If the
use of science in the business succeeded, it was regarded as a
kind of windfall. The success of the business depended, as
in the past, upon the efficiency of production and selling.
Businesses, at any rate all except the very largest, tend to be
dominated by one of the gi^eat functional departments, such
as that concerned with selling, in which case production is
attuned to the needs of the sales department. In others, the
more actixe and aggressive groups are those engaged in pro-
duction, and these companies sell what they produce rather
than produce what they need to sell. But with the gi'owth
of industrial research, the development and introduction of
new products have become of such great importance that
there are companies in which quite avoAvedly the research
and development departments represent the primary driving
force; the production departments manufacture the new
products and the sales department sells them. In many com-
panies the economic value of the research work is now fully
recognized, and the financial journals devote a considerable
amount of space to the development of industrial science.

The number and size of the industrial research laboratories
have increased rapidly during the last thirty years. In the
excellent monograph issued by the National Resources Plan-
ning Board, it is stated that since the first World W^ar, indus-
trial research in the United States has assumed the propor-
tions of a major industry.* In 1920, about three hundred
laboratories xvere engaged in industrial research. In 1940,
the number had increased to more than 2200. The total
personnel had groxvn from approximately 9000 to over

* Report of the National Research Council to the National Resources
Planning Board, p. 37, U. S. Government Printing Office, Washington,
D. C, 1941.

204 . THE PATH OF SCIENCE

70,000. An estimate of the total expenditure on industrial
research in the United States, based upon the cost per man
in a number of laboratories, gives a total figure for 1940 ex-
ceeding $300,000,000. Since the increase in industrial re-
search continued through the years of war, it is not unlikely
that the total expenditure for 1945 was of the order of
$500,000,000. Incidentally, these figures offer a complete
refutation to the gloomy prophesies of certain "liberal" think-
ers of thirty years ago. At that time, one of the arguments
that Justice Brandeis used against the development of large
units in industry was that they would infallibly neglect
technical and scientific research and, thus, progress would
be stifled by the operation of what he considered to be
monopoly.*

Industrial research in the United Kinordom has o^rown
rapidly both before and during the war. According to Dun-
sheath, f the direct expenditure of the Department of Scien-
tific and Industrial Research was about $2,000,000 and of
the Research Associations J (in 1938) about as much again.
Expenditure by private companies is much lower than in
the United States but is still very considerable. A survey
by the Federation of British Industries published in the
early part of 1946 recorded 9000 graduate scientists engaged
on research and development in British industry, with a
total expenditure thereon of about £20,000,000 annually—
a proposed increase of research staff of 25 per cent and of
laboratory space of more than 2,000,000 square feet.

Industrial laboratories may be classified in three general
divisions:

1. Plant laboratories exerting analytical and testing con-
trol over materials, processes, and product.

* The statement by Brandeis was actually quoted in 1944 by N. Kaldor
at a conference on industrial research in England as if it represented a
fact instead of a quite erroneous prediction!

f P. Dunsheath, "Industrial Research in Great Britain: a Policy for
the Future," Journal of the Royal Society of Arts, 91, 167, 242 (1943).

iPage 211.

APPLIED SCIENCE AND INDUSTRIAL RESEARCH 205

2. Development laboratories working on improvements in
product and processes, tending to lessen cost of production
and to introduce new products on the market.

3. Laboratories working on pure theory and on the funda-
mental sciences associated with the industry.

Laboratories of the first type are so obviously necessary
that practically all plants are equipped with them, and fre-
quently each department of a factory maintains its own
control laboratory.

Laboratories of the second class are frequently called "re-
search" laboratories and have been largely instrumental in
introducing scientific control into industry. In such a devel-
opment laboratory, the work ranges from the simplest and
most obvious alterations to problems of extreme difficulty
involving scientific knowledge of a high order. The func-
tion of the development laboratory is to collect ideas from
all sources and apply them to manufacture. Those investi-
gations of the pure research section that result in new prod-
ucts or methods will usually pass through the development
branch to the manufacturing departments. The man -^vho
has been in charge of an investigation in pure research should
follow his work through the development branch into the
manufacturing departments until it becomes a recognized
and established feature in manufacture.

It is often desirable for the laboratory itself to have facili-
ties for carrying new developments to the stage of production,
and, indeed, in many laboratories it is considered necessary
not only to manufacture on a small experimental scale but
even to place certain new products on the market, transfer-
ring production to the works only when the demand is such
that a full-scale manufacturing organization is required to
meet it. This is particularly useful in the case of products
that are new to the industry and that require novel and diffi-
cult manufacturing methods and, at the same time, the de-
velopment of a new market.

If the whole future of an industry is dependent on the work
of the research laboratory, then not merely an improvement

206 THE PATH OF SCIENCE

in processes or a cheapening in the cost of manufacture will
suffice, but fundamental work is required in the whole field
in which the manufacturing firm is interested. For this pur-
pose something very different from the usual plant laboratory
is needed, and to inaintain progress, the w^ork of the research
laboratory must be directed primarily toward the funda-
mental theory of the subject. This is a point that has some-
times been overlooked in discussions of industrial scientific
research, much stress being generally laid upon the imme-
diate returns to be obtained from plant laboratories and upon
the advantage of scientific control of the operations. But in
every case where the effect of research ^vork in industry is
very marked, that work has been directed not toward the
superficial processes of industry, but toward the fundamental
and underlying theory of the subject.

According to C. M. A. Stine of the Du Pont Company:

Fundamental research and what may be termed "pio-
neering applied research" should be differentiated. The
distinction is based principally upon the scope of the work
and the extent to which it is limited by certain recognized
practical objectives. In general, research undertaken upon
some broad general subject, such as the structure of cellu-
lose, belongs to the category of fundamental research.

On the other hand, if a company engaged in the produc-
tion of textiles coated with cellulose derivatives, or in the
manufacture of photographic film, or of other products
utilizing derivatives of cellulose, undertakes research aimed
at the development of new cellulose derivatives, in the hope
of developing such derivatives as might exhibit useful prop-
erties fitting them for application in manufactured prod-
ucts, the w^ork becomes pioneering applied research. After
the discovery of a new cellulose derivative and the evalua-
tion of its properties, the next step might be actually to
manufacture it, wiiereupon the investigation assumes the
complexion of ordinary applied research.

The investigation of monomolecular films by a producer
of electrical equipment might be fundamental research,
whereas the investigation of monomolecular films by an
oil refiner engaged in the production of lubricants might
be largely in the field of applied research. Thus, the classi-

APPLIED SCIENCE AND INDUSTRIAL RESEARCH 207

fication of the research depends upon the character of the
problem and the nature of the agency carrying on the
investigation.*

Fundamental research involves a laboratory very different
from the usual plant laboratory. It requires a large, elabo-
rately equipped, and heavily staffed laboratory engaged
mainly in ^vork that for many years is unremunerative and
that, for a considerable time after its foundation, produces
no results that can be applied to manufacture. Such a lab-
oratory has a cumidative value as its work is continued. At
the beginning it is of service to the industry in bringing a
new point of view to bear on many of the problems; it is of
value especially in establishing standard methods of testing
and standard specifications for the purchase of raw materials,
while much of its energy may profitably be devoted to the
investigation of the use of the products of the industry.
Many large industrial laboratories, indeed, are maintained
as much in the interests of the customer as for the produc-
tion departments. A research laboratory of this type also
studies the merits of new industrial propositions of which
the value has not been commercially established, but all
these early uses of the laboratory eventually prove subsidiary
to its main work on fundamental problems. When this main
line of research begins to bear fruit, it- absorbs the energies
of both the laboratory and the factory. This, however, takes
many years.

As explained previously, research laboratories may be of
the divergent or convergent type. Those of the Bell Tele-
phone Company, the General Electric Company at Schenec-
tady, the W^estinghouse Electric and Manufacturing Com-
pany, and the Eastman Kodak Company are essentially of
the convergent type. The work of the research laboratory of

* Charles M. A. Stine, Vice President, E. I. du Pont de Nemours and
Company, Wilmington, Del., "Fundamental Research in Industry, Re-
search—A National Resource, II. Industrial Research." Report of the
National Research Council to the National Resources Planning Board,
p. 98, U. S. Government Printing Office, Washington, D. C, 1941.

208 THE PATH OF SCIENCE

the Eastman Kodak Company is concentrated primarily on
the study of photography. The extent of its work in this
field is shown by its publications. In the last thirty years, the
laboratory has published about a thousand scientific papers,
and of these by far the greater number deal with some aspect
of the theory of photography. To take a single year: In 1936,
papers were published on the formation of the latent image;
the analysis of gelatin; the absorption spectra of cyanine dyes;
the theory of image errors in lenses; the measurement of
photographic densities; the stability of developers; the meas-
urement of graininess; the decomposition of cellulose ni-
trate; the effect of stilfur compounds on photographic emul-
sions; and the application of quantum mechanics to the
process of exposure.

In the divergent group of laboratories are included many
research institutions that are interested in science in general
or in science as applied to industry and that attack any prob-
lem promising progress in knowledge or, in the case of an
industrial laboratory, financial return. The greater number
of university and industrial laboratories are necessarily of
this type. It would be a disadvantage for a university lab-
oratory, whose primary business is training students, to be
too narrowly specialized. Specialized university laboratories
are desirable only for post-graduate students. Industrial lab-
oratories, on the other hand, must be prepared to deal ^vith
any problems presented by the plant. As these are of all
kinds, covering generally the whole field of physics, chem-
istry, and engineering, it is impossible for many plant labora-
tories to specialize except in so far as they deal ^vith the plant
processes themselves.

The position of an industrial research laboratory in the
organization and its relation to the other departments of
the company with which it is associated are of considerable
importance.

Research laboratories have originated in many different
ways. The earliest grew out of plant testing and control
laboratories and were, therefore, responsible directly to the

APPLIED SCIENCE AND INDUSTRIAL RESEARCH 209

works manager. More recently, laboratories have generally
been established as independent departments of the company
and are responsible to the general manager only. If an execu-
tive of a manufacturing company is a technical scientific
expert, he may have felt the need for a laboratory and estab-
lished one under his own control. In this case, the laboratory
is necessarily very closely associated with his W'Ork. A labora-
tory may have been established under a separate director, not
himself associated with the executive officers of the company,
as a reference department for the executives. In this case also
the laboratory is closely associated with the officers of the
company and tends to be concerned largely with questions of
policy and the introduction of new products. In a large com-
pany, a research laboratory is usually established as a separate
department, having its own organization and available as a
reference department for all sections of the company.

The position that the research laboratory should occupy in
an industrial organization is perhaps best determined by the
criterion that the research department should be responsible
to the officer of the company wdio is in charge of the develop-
ment of new products. If the introduction of new products
is in the hands of the plant organization, the research depart-
ment should be responsible to the plant manager; if there is
a definite development department, or, if new products are
introduced through the agency of some definite executive, it
is to that executive that the research department should be
responsible. The research laboratory, in fact, should be asso-
ciated primarily wdth development.

It cannot be too strongly emphasized that the success of the
research laboratory depends upon the application of its work.
Since application naturally depends to a great extent upon
co-operation with other departments of the company, every-
thing that promotes such co-operation is to be encouraged
and anything different is to be discouraged. There is some
question, on the other hand, w^hether the laboratory^ re-
sponsible for original w^ork leading to new products should
deal with manufacturing problems. If a research staff en-

210 THE PATH OF SCIENCE

gaged on fundamental research is frequently called upon to
deal Tvith plant problems, the more fundamental work is
subject to interruption and disrupted efficiency. At the same
time, the study of plant problems suggests many important
lines of work to the laboratory staff. Nothing is more stimu-
lating to the co-operation of manufacturing departments Tvith
the laboratory than the successful solution by the laboratory
of problems submitted by the plant departments. It is some-
times difficult for the laboratory to solve such problems. \^ery
often the practical solution depends upon minute knowledge
of the working process; and a laboratory is expected in some
supernatural way to solve problems that have baffled men
thoroughly acquainted with all aspects of the process. But
even if the laboratory fails to solve a given problem to the
satisfaction of the department concerned, the study of the
process itself is quite likely to result in suggestions which may
be of more value than the solution of the problem submitted.
If the manufacturing organization is of sufficient size, a sepa-
rate laboratory for the more fundamental problems may be
desirable, leaving special departments of the laboratory better
acquainted with manufacture to undertake those from the
plant. Thus a link is formed between the purely scientific
research and the manufacturing departments.*

While a large laboratory fully equipped for fundamental
research represents the most effective means of prosecuting
industrial research, such a laboratory can be maintained only
by large manufacturing companies, as the cost of maintenance
is very heavy and only a large company can afford such an
expenditure. On the other hand, national industry is not
carried on principally by large manufacturing companies,
either in the United States or in Great Britain. In Britain,
98 per cent of the factories are said to employ less than a
thousand workers, and 80 per cent less than a hundred. Prob-
ably the situation is the same in the United States. The chief

* P. G. Nutting, "Research and the Industries," Scientific Monthly,
7, 149 (1918).

APPLIED SCIENCE AND INDUSTRIAL RESEARCH 211

problem, therefore, in the application of science to national
industry is presented by the smaller businesses that cannot
afford to maintain a really large laboratory. In Great Britain,
the solution offered by those responsible is membership in
one of the research associations organized under the Depart-
ment of Scientific and Industrial Research to serve entire
industries.

A conference on problems of scientific and industrial re-
search was held in 1944 at Nuffield College, Oxford, England,
and an excellent summary of the discussion was published by
the Oxford University Press.* In this report the operations
of the research associations are described. The British Re-
search Associations ^v ere formed during the first World War
when the British government at the end of 1916 announced
its intention to allot £1,000,000 for the formation and main-
tenance by the Department of Scientific and Industrial Re-
search of approved associations for research in co-operation
with the industries. The plan was to form associations of
which approximately half the cost would be paid by the in-
dustries and the remainder by the government, these asso-
ciations to carry out systematic research and to apply science
to the problems of industry. The scheme was widely ap-
proved, and by the end of 1920, thirteen research associations
had been formed. The total number to date is just under
thirty.

In the twenty odd years since the first associations were
formed, the plan has met with little opposition, yet those
men who have been most closely connected ^vith the research
associations have, on the whole, been disappointed, a disap-
pointment which is commonly attributed to the lack of funds.
The sum of £1,000,000 was, of course, utterly inadequate for
research relating to the whole of the British industry; yet it
w^as found difficult to raise an equal sum from the industries.
Undoubtedly, funds could be raised after a research associa-

* Problems of Scientific and Industrial Research, Oxford University
Press, April 1944.

212 THE PATH OF SCIENCE

tion had demonstrated its value; on the other hand, it is
very difficuk for a research association to do this until it has
the funds. After the first ten years' work of the department,
the advisory council in their review in 1925-1926 said that,
when they reflected how trivial in relation to the total output
of an industry is the expenditure needed, they could not be-
lieve that private enterprise would fail to maintain on an
adequate basis the associations that had already shown their
value. Nevertheless, the council believed that voluntary con-
tributions would be inadequate and favored the introduction
of some kind of compulsory levy. After this report had been
issued, there was a gradual improvement in the financial sup-
port of the associations, and under war conditions it has in-
creased, although it is still inadequate.

The Nuffield report goes on to discuss the objectives of the
research associations. Should they, for instance, undertake
long-term programs of applied research, study the scientific
facts on which the processes of the industries are based, and
merely publish their results, leaving it to the firms to apply
them to their own work? Or should the research association
translate as much as possible of its work into results that can
be applied by the industry even though the individual firms
have no adequate scientific staffs? Again, should the associa-
tions devise their own research programs or should they be
ready to study problems proposed by any subscribing firm and
advise such firms how to deal with their o^vn specific prob-
lems? The conference felt that there could be no uniform
answer to these questions. The answer would depend upon
the industry. Modern scientific industries such as the elec-
tric or scientific instrument industries need a different policy
from that of the older technologies, such as the textile or
leather industries. In the more technical industries, the in-
dividual firms have their own laboratories, and they allot to
the research association only long-term problems suitable for
collective effort. In the older industries, where the processes
are still largely based on tradition, the research associations
have a double function. On the one hand, they must study

APPLIED SCIENCE AND INDUSTRIAL RESEARCH 213

short-range problems, ^vhich offer immediate results; on the
other, they should certainly undertake a long-range study of
the fundamental scientihc problems of the industry that have
been neglected in the past. Thus the older industries need
an active program of scientific research much more than the
modern industries, but it is much more difficult to do this
work and to obtain support for it. Some industries, such as
those dealing with textiles, are divided between the succes-
sive stages of production. The research association must
think in terms of the industry as a whole rather than of a
single section. In the cotton industry, for instance, there are
not only the problems of the spinning, weaving, dyeing,
bleaching, and finishing branches, but there are also the
problems of the cotton plant itself and of the raw material
that it produces.

Most research associations are faced with the problem of
combining a variety of functions in one institution. If the
association concentrates on the major long-run problems,
many of the smaller firms with immediate difficulties will be
dissatisfied. If, instead, it deals primarily with service work,
it may degenerate into a mere testing station, and will cer-
tainly lose the good will of larger firms to whom it is giving
little information of value.

Research associations cannot take the place of the research
laboratories of the industry itself. In the latter, the new de-
velopments achieved are important for the individual firm.
They give that firm advantage over its competitors and an
improved position in the industry, and they bring to the
laboratory, therefore, the enthusiastic support of the other
parts of the organization. No company capable of doing its
own research will pass to an association serving its competi-
tors equally with itself the problems that seem to it most
promising.

While the British Research Associations have undoubtedly
been useful to the small units in their industries, they cannot
be considered on the whole to have promoted the establish-
ment of research laboratories in the individual companies of

214 THE PATH OF SCIENCE

the industry. The examples of successful research have, of
course, tended in this direction and, in many cases, may have
induced manufacturers to form their own research groups.
But their effect in this direction has been offset to some ex-
tent by the tendency on the part of the financial heads of the
industries to assume that membership in a research associa-
tion is sufficient to take care of their scientific needs.

In the United States there are a few organizations com-
parable to the British Research Associations. Most firms,
however, have their own centralized research laboratories or
utilize the facilities of large endowed laboratories such as the
Mellon Institute, Battelle Memorial Institute, or the Armour
Research Foundation, w^hich may conveniently be called
Technological Research Institutes.

The Mellon Institute, at the University of Pittsburgh, the
prototype of these laboratories, was founded in 1911 to carry
out the scheme of industrial fellowships originally introduced
by Robert Kennedy Duncan of the University of Kansas.
Duncan adopted this scheme partly to train students in indus-
trial research and partly because he felt that such research
work as was attempted in small factories was often undertaken
under very bad conditions.* He felt too that the manufac-
turer often has neither the knowledge nor the experience
requisite to establish successful research, that he is not will-
ing to allow sufficient space or equipment for it, and that a
man w^orking alone in a small industry is hampered both by
lack of the stimulation he might get from association with
other scientific workers and by want of proper skilled direc-
tion of the work.

In such a laboratory as the Mellon Institute, the manu-
facturer can arrange to have the work done under conditions
that insure that he alone obtains the result of the work; and
yet the research men will have the advantages of the Insti-
tute, contact with other scientific workers, the availability of

* R. K. Duncan, "Industrial Fellowships," Journal of the Society of
Chemical Industry, 28, 684 (1909).

APPLIED SCIENCE AND INDUSTRIAL RESEARCH 215

sources of information such as a reference library, and direc-
tion of the work by experienced administrative officers of
the laboratory. According to the system in operation at the
Mellon Institute, a manufacturer having a problem that re-
quires solution may become the donor of a fello^vship, ^vhich
provides the salary of the fellow selected, and the Institute
supplies laboratory space and the use of all ordinary chemicals
and equipment.

In 1944-1945, there were 94 industrial research programs
in operation, employing 242 scientists and 232 assistants. The
service staff of the Institute numbered 169, and total expendi-
ture was slightly more than $2,000,000. The subjects under
investigation were diversified: for instance, catalysis as related
to the synthesis of butadiene; utilization of corn products,
such as starch, oil, and zein; improvement in ^vaste disposal
in streams; structural glass; coal and coke products; synthetic
lubricants; properties of cotton fibers; petroleum products;
organic silicon resins; industrial hygiene.

The Battelle Memorial Institute was founded by Gordon
Battelle, industrialist, whose will provided for the building
and endowment of an independent institute "for the purpose
of education . . . the encouragement of creative research
. . . and the making of discoveries and inventions" for in-
dustry. Its operation began in 1929.

In its plan, Battelle provides the plant, equipment, and
staff. The company or group under whose auspices the re-
search is done pays for the time of the personnel assigned to
the project and the out-of-pocket costs. Sponsored research
at Battelle in 1945 was estimated at $3,000,000, and the lab-
oratories housed a staff of approximately 800 technologists
and assistants. Each project undertaken is the responsibility
of the Institute as a whole, and, using the methods of group
research, all equipment and the knowledge of the entire staff
of technologists in diversified fields can be brought to bear
on the solution to a technological problem. In addition to
its research work, Battelle conducts a program that offers

216 THE PATH OF SCIENCE

training to selected young men who plan to follow industrial
research as a career.

The Armour Research Foundation developed in 1936 from
industrial research directed by the faculty of the Armour
Institute of Technology. It has grown very rapidly and in
the year 1943-1944 had in operation 117 long-term projects
with a total budget of $1,670,000. It carries on its work
under a plan whereby each problem is subjected to the col-
lective thinking and co-operative action of a permanent staff
of research workers in many fields of science, and in which
every possible routine operation is removed from the research
T worker's responsibility and placed in the hands of auxiliary
service laboratories.

In general, these technological research institutes are in-
creasing both in size and in number and are rendering a great
service to American industry. During the year 1945 alone,
two new ones were founded— the Southern Research Insti-
tute, at Birmingham, Alabama, and the Midwest Research
Institute, at Kansas City, Missouri. Research facilities are
thus made conveniently available to industries within
these regions. The institutes provide equipment, often on
a semi-plant scale, that would not otherwise be available for
experimental work, and they often specialize in certain fields
of work with a long-range, continuous progiam approximat-
ing to the work of a specialized research group. They are
also of great value for training men; and in many cases manu-
facturers who have endowed an industrial fellowship even-
tually establish research laboratories of their own, employing
in them the men who have carried on the work as fellows.
These technological institutes thus serve as nurseries for pri-
vate industrial research laboratories in addition to doing work
directly and training men. This influence is of the greatest
importance, because however effective is the actual research
work done in an external laboratory, that ^vork should supple-
ment rather than take the place of scientific work done as an
integral part of the business.

APPLIED SCIENCE AND INDUSTRIAL RESEARCH 217

The technological status of industry has little permanency.
It is often assumed that those hrms that have developed large
amounts of technical skill Avill continue to dominate their
industries and that other industries will remain ^vithout any
corresponding scientific guidance. This is not true, how-
ever, as the Nuffield College report points out. Industrial
progress depends not only on the existence of large firms
carrying on research over a wide field but equally on the
continual emergence of ne^v^ firms animated by a scientific
spirit in their approach to industrial problems.

Before 1920 the petroleum industry of the United States,
one of the most wealthy and po^verful industries, did very
little scientific research. Since then it has not merely estab-
lished scientific divisions and research laboratories, but it has
come to the very forefront of industrial scientific research
and has developed entirely new branches of industrial chem-
istry. This is no rare phenomenon. Again and again, a
change in management or the emergence in management of
one individual has revolutionized a manufacturing company
and eventually an industry. Thus, instead of a picture of a
static industrial world in w^hich there are giants and pygmies,
the facts show a Avorld in ^vhich the giants must ^vork unceas-
ingly to remain strong and the pygmies are continually grow-
ing and asserting their right to a place in the sun.

It is asserted far too often that "small businesses cannot
afford to support scientific research." Few businesses can
afford to support research. They carry out their research, as
they do the rest of their operations, for profit, that is, to be
supported by it; and if they are successful, they do not remain
small, they gro^v. When Ernst Abbe joined Carl Zeiss, he
entered a very small business, ^vhich became the leading op-
tical industry of the world. Wlien Ludwig Mond joined John
Brunner, he founded a business w^hich became one of the
chief components of Imperial Chemical Industries.

The Zeiss firm or the alkali works of the future are today
small firms with an active leader imbued Avith the spirit of
science. The problem for the small business, in fact, is not

218 THE PATH OF SCIENCE

how to get its scientific work done by somebody else but how
to find that active leader.

When the first industrial research laboratories were or-
ganized, in the early years of this century, the managers of
industrial undertakings realized that they required a group
of investigators whose results could be applied to that par-
ticular industry. They realized also that they themselves did
not understand how scientific work ^vas carried out or how it
could be applied. They therefore chose an individual, fre-
quently a teacher of science at a university, who was em-
ployed to enter the industrial organization as director of re-
search. Characteristically, the first task assigned to the re-
search director was usually to build a laboratory, an opera-
tion which he undertook with the enthusiasm and zest born
of ignorance, since very few scientific men know anything
about buildings. Having built the laboratory, the research
director proceeded to organize a staff and to start doing scien-
tific research. The success of these early pioneers varied con-
siderably, but almost all were successful to some extent.

The efficiency and accomplishment of an industrial labora-
tory depend to a very large extent upon the director. In fact,
it may be said of research laboratories, as of other human
institutions, that they are the reflex of a man. The large in-
dustrial research laboratories are at the present time passing
through a critical stage, in which the founding directors are
passing and are being replaced by their successors. Their
experience shows to how great an extent the success of a re-
search laboratory is dependent upon the individuality of its
director. There are laboratories which have had a distinctly
successful career and which, with the passing of the directors
who organized and developed them, have fallen into obscurity.
Moreover, it is extremely difficult to find suitable men to
direct industrial laboratories. Such a man must be both a
scientist and an executive, and he must have an interest in
and a capacity for the commercial operations of the business
in which he is eng^as^ed. The reason that the director of an
industrial research laboratory must be interested in the com-

APPLIED SCIENCE AND INDUSTRIAL RESEARCH 219

mercial operations of his company is that he must make his
laboratory pay; and if he does not know how to do that, no
one else can do it for him.

It is even more difficult to select a director for the research
department of a small company than for the large laboratory
of a great manufacturing concern. The ideal would be a man
who combined the necessary scientific ability and experience
with definite capacity for the executive operation of a busi-
ness, so that he could very soon become one of the senior of-
ficers in charge of the business.

Unfortunately, though the necessary characteristics are not
really rare, there is no source to which those responsible for
the conduct of business can turn for guidance in their selec-
tion. What is needed is a staff college or university depart-
ment where scientists ^\ ho wish to specialize in the applica-
tion of science can obtain post-graduate training- of the type
supplied by the Harvard School of Business Administration
and wdiere they will be known to be available for positions.
The establishment of such colleges or departments in Great
Britain and the United States would go far toward supplying
the present need for the increased application of science in
the smaller businesses.

C. G. Renold * in his address to the Manchester Chamber
of Commerce realized that the application of science to a
small business required the services of a scientist with execu-
tive functions. Since he assumed, however, that such a con-
cern could not set up its own research department and would
rely on a co-operative laboratory, he suggested the appoint-
ment of a "Scientific Liaison Officer" to formulate problems
and interpret the answers into practice. If such an officer
were competent, he would almost certainly want to do re-
search work under his own direction and would establish a
laboratory. Perhaps, however, there are business manage-
ments to whom the idea of a "liaison officer" might seem less
startling and dangerous than a research director.

* Science and Industry, p. 28, Manchester Chamber of Commerce,
King St., Manchester 2, England, 1944.

220 THE PATH OF SCIENCE

The actual direction of industrial research is a matter of
great importance and one on which there is much difference
of opinion. The fundamental problems are what researches
are to be done, along what lines is work to be started, how
long is it to be kept going when the prospects for success
look bad, when is loss to be cut and the work abandoned?
These problems are at the heart of the whole matter, and the
decisions with regard to them constitute the direction of
research.

As business managements have become familiar with the
use of science and its importance to industry has increased,
manao^ements have tended to become more and more inter-
ested in the actual direction of the scientific work. They no
long^er feel that the research director can be left to initiate
work along the lines that he thinks are likely to be profitable,
to exploit his idiosyncrasies, or even to play his "hunches."
They consider it necessary to operate the research and de-
velopment sections because the future of the business depends
upon it. The research director must expect to receive direc-
tion and instructions from the management of the company,
and must expect to have to justify the plans that he puts for-
ward. This tendency is common among almost all the com-
panies in which industrial research has been successful.

As a result of the anxiety of management to supervise the
work of the research department, there has arisen a system of
control that is sometimes known as the project system. Ac-
cording to this, the research manager proposes a plan of re-
search divided into a large number of individual projects, to
each of which are allocated certain definite funds. This plan
is considered by various groups and, finally, by a special com-
mittee of the executives of the company assigned to the task,
and is approved both in whole and in detail. The work done
is reported periodically, and the expenditure on each project
is considered in relation to the original allocation of funds for
that purpose, new funds being allocated as necessary, and each
project being finally closed either as a success or as a failure

APPLIED SCIENCE AND INDUSTRIAL RESEARCH 221

that must be abandoned. This project system may be re-
o^arded as one extreme in the control of the research work.

The other extreme, almost universal in the early days of
industrial research, is the direction of the research by an indi-
vidual responsible only to the top management of the com-
pany and ^vithout supervision in his own work. To him, the
company entrusts the funds that it proposes to spend, and
from him the company asks only results, with such account-
ing controls as insure merely that the funds have been ex-
pended for research in accordance with ordinary business
principles. This method regards the whole of the research
expenditure frankly as a gamble in which the management,
having hired an expert in the field, leaves it to him and to
his men to spend their funds in the hope that the company
will get an adequate return. The project system regards
research as a business which can be organized, and, ^vhile
recognizing that some of the projects will fail, proposes that
the successful ones should carry the failures. Viewed in this
way, the project system will be far more attractive to business
management than the opposite system, in which control over
the choice of research projects is exercised only by the research
men.

In assessing the relative advantages of the project system
and of the individual direction of industrial research, we
must consider their relative efficiency and their cost. The
overhead cost of a laboratory operated on the project system
is necessarily greater than that of a laboratory operated with-
out it, so that it should be demonstrably more efficient if it is
to be worth while.

The development of new products for the market, like
production itself, can be organized and planned; so can the
service work. But when we turn to the scientific '^vork of the
laboratory, to the researches from which new discoveries may
come, any systematized planning becomes difficult and per-
haps impossible. This can be met by the direct allocation of
certain funds for this fundamental ^vork. It enables the scien-
tific men to carry out work that no committee ^vould approve

222 THE PATH OF SCIENCE

or could direct and, to a great extent, meets the most serious
objection to the operation of the project system.

For the direction of the service and the development prob-
lems, which in most laboratories represent the greater portion
of the work, the project system would be preferable were it
not for the fact that it costs a great deal more. The project
system requires a complete accounting system, a great deal of
reporting involving stenographic assistance and filing, and,
in addition, it consumes an immense amount of time, both
of the scientific staff and of the management of the company,
spent on the careful consideration of the various projects. In
many large laboratories, much of the time of the senior
scientific staff is devoted to conferences and committee meet-
ings at which the problems of the laboratory are discussed in
detail. This is so serious that some laboratories openly state
that it is undesirable for the best scientific men to be group
leaders since they are left little time for scientific work and
that the scientific experts should have their work directed by
a group leader who is essentially a business man with scien-
tific training. It is very difficult to calculate accurately the
relative costs of the two systems, but with certain simplifying
assumptions, it is not impossible to make guesses.

1. Let us assume that in both systems the scientific men
are paid the same amount.

2. Let us assume that in both systems the scientific men
are of the same average ability.

Then the cost by the two systems per scientific man employed
for the same total amount of ^vork done can be measured by
the total cost of the laboratories. Accordino^ to available figr-
ures, the cost of some laboratories run by the project system is
approximately $10,000 a year for each scientific man working
in the laboratories; in laboratories without the project sys-
tem, in which the work is directed only by the scientific staff,
the average cost is of the order of $7000 per man per year.*

* These figures date from 1930; they have undoubtedly increased, but
the proportion will be unaffected.

APPLIED SCIENCE AND INDUSTRIAL RESEARCH 223

Thus, under the project system, the work of a scientific man
costs approximately 40 per cent more than if there were no
external control of the work done. In addition, it must be
remembered that no allowance is made for the time of the
company executives not in the laboratory who assist in the
supervision of the laboratory work.

For the project system to be worth while, therefore, from a
purely commercial point of view, it must be assumed that
approximately 40 per cent of the work of the scientific men
in a laboratory operating without the system will be mis-
directed and could be eliminated by the use of the project
system. It is doubtful that this is the case, and it is probable
that the project system materially increases the cost of operat-
ing a research laboratory and does not produce an equivalent
efficiency in results.

In the unplanned laboratories, many mistakes are made.
These are evils of commission. Probably the project system
avoids them to some extent, but under the project system
there are more likely to be errors of omission. The errors
of commission are visible to the management; the errors of
omission are invisible because unknown. If a piece of work
that costs $100,000 ends in failure, it is obvious, and it ap-
pears reasonable to everybody that the man responsible should
be broug^ht to account for it and told not to make the same
mistake another time. There is no real danger of his doing
so, of course; next time he will make a different mistake. On
the other hand, an error of omission, in which the possibility
of a most valuable development is not recognized, is unknown
even to the director himself, since he will be satisfied, in the
characteristic human fashion, that his judgment was probably
right. There is only one case where an error of omission can
be evaluated. It is where it has been decided to make a
change in the plans— not to do a thing or to stop doing some-
thing; then, for no reason directly connected with the de-
cision, it is not put into effect and the work is carried on.
For instance, a suggestion for a particular piece of research
is considered by the scientific men concerned and by the

224 THE PATH OF SCIENCE

director in the light of the information he has. They decide
not to do it, but then the legal department reminds them:
"You have forgotten that we made a contract in which we
agreed to carry out this piece of work." The success or fail-
ure of the work, then, is a clear test of the validity of the
original decision. In three cases from the author's experi-
ence, where the decision had been made to abandon a piece
of work but where it was carried forward without any change
in opinion and for quite other reasons, the work proved en-
tirely successful. Experiences of this kind demonstrate how
difficult it is to make plans for the conduct of research and
even the decisions essential for its operation.

The experience of the last thirty years suggests that the
greatest success has attended those industrial research labora-
tories in which the director has been permitted a high degree
of autonomy and an assurance of continued support. Indus-
trial research is an adventure; it is even a gamble, though
one in which the odds are on success, provided that the ^vork
is continued in spite of delays and discouragements. Such
an adventure demands from its sponsor much courage and
much confidence. But if the director and his staff are well
chosen, the confidence will not be misplaced, and the re-
wards will be commensurate with the risks.

Chapter X
THE PATH OF SCIENCE

In the early chapters of this book, we followed the growth
of human civilization. We saw in the history of that giowth
the mountins: knowledsie of science, visible first as the ration-
alization of technology and then pursued for its own sake. It
was found convenient to represent the history of civilization
as a helix, in which the cyclic structure discernible in the arts
is shown in the coils, and the cumulative giow th of knowl-
edge is shown as the vertical component. It will be recalled
that at the beginning the vertical component was small and
the coils, representing the cycles of civilization, lay closely
upon one another. With the coming of the Graeco-Roman
culture, organized knowledge developed, and in the seven-
teenth century, after the invention of printing and the dis-
covery of the experimental method, modern science came into
existence. At the present time, the progress of science is so
rapid that it dominates the whole world picture and chal-
lenges the ability of the leaders of mankind to meet the social
changes that it produces.

As we follow the path of science through the ages, ^ve can
note certain points at which the scientific method was applied
to a new group of the problems that confronted mankind.
These are not the points at which the major discoveries and
inventions were made; they are the occasions when new ap-
plications of the scientific method emerged. Perhaps the
first of these occasions may be chosen as that at which causa-
tion was realized— when it was understood that like causes
beget like effects and, as a result, rational technology was
born. Another turning point in history came after the in-
vention of writing, when the methods and formulae for tech-

225

226 THE PATH OF SCIENCE

nology were written down and so preserved and transmitted,
a point that in Egyptian history is associated with the work of
the architects and engineers who carried out the great build-
ings of the Old Kingdom, including the Pyramids. In the
later Greek period, from 400 B.C. to 200 b.c, the relation of
science to philosophy emerged; logic and mathematics evolved
as the tools of thought; and the epistemology of science de-
veloped. In the seventeenth century, the experimental
method was discovered; and the development of the body of
valid ideas, which today we term science, proceeded apace.

At the beginning of the twentieth century, the experi-
mental method of science ^vas found to be directly applicable
to the control of industry, and from that application has come
the rapid growth in the efficiency of production that has
marked the present age.

But the path of science is not ended. As Joan Evans says:
"The present should retain its true proportion ... a mo-
ment between an infinite past and a hurrying future." In
that future, there are already signs of a new field for the
application of the methods of science, the field of the social
sciences— sociology, economics, and politics.

The application of the methods of science to the social
sciences is by no means novel. Plato and Aristotle discussed
it and, indeed, regarded the understanding of the principles
of political economy as the chief end of scientific investiga-
tion. Francis Bacon laid down the application of science to
politics as the principal object of the pursuit of knowledge.
The philosophers of the eighteenth and nineteenth centuries
based much of their sociological and economic doctrines upon
the supposed nature of scientific knowledge. Two of those
philosophers, holding very different political views, Herbert
Spencer and Karl Marx, founded all their sociological pre-
cepts upon what they believed to be the teachings of science.

A. N. Whitehead, however, points out that the whole
tradition of the thinkers who have written on sociology and
political philosophy is warped by the assumption that each
generation follows the practices of its fathers and transmits

THE PATH OF SCIENCE 227

to its children the conditions that it finds in society.* For
the first time in history, this assumption is false (compare
Chapter I, page 10 ff.). Moreover, since the social and eco-
nomic changes characteristic of the present age are produced
by the development of science, they increase as the develop-
ment of science accelerates. As Whitehead says: "Today we
are at the beginning of a new crisis of civilization, which gives
promise of producing more fundamental change than any
preceding advance. . . . The whole of human practical ac-
tivity is in process of immediate transformation by novelties
of organized knowledge." f This is true because the growth
of science is not only very rapid, but it is still accelerating.
The production of new science, in fact, is accelerated by the
science already produced; and this phenomenon is parallel
to that which the chemist knows as an autocatalytic reaction.
Autocatalytic reactions are those in which the product of
the reaction itself increases the rate at which the reaction
proceeds. If we heat guncotton, that most important ex-
plosive, it gives off a little nitric acid, which makes it decom-
pose faster, so that it gives off more nitric acid and decom-
poses faster and faster until finally the heat generated may
be sufficient to produce an explosion. Any chemical reaction
that produces heat will increase autocatalytically if the heat is
not conducted away. Such a reaction is interesting to watch.
We put the solvent in a vessel, add all the ingredients, and
perhaps warm them a little. Then, the reaction starts and
generates heat as it proceeds. It goes faster and faster, and
the solution may rise in the vessel and froth; and then, as the
reaction decreases and the materials are used up, the solution
sinks again. If there is not enough room, the vessel will boil
over; if there is enough room, it will undergo a complete
transformation into a new system. The termination of the
reaction is produced by the exhaustion of one of the com-

* A. N. Whitehead, Adventures of Ideas, p. 117, New York, The Mac-
millan Co., 1933.

f "Statesmanship and Specialized Learning," Proceedings of the
American Academy of Arts and Sciences, 75, No. 1, p. 5 (1942).

228 THE PATH OF SCIENCE

ponents, just as the production of plankton in the sea is lim-
ited by the supply of mineral salts, principally phosphate, in
the water. In northern latitudes, the phosphate in the sur-
face water is renewed by the change of temperature in the
spring and in the fall. As the temperature of the surface
water in the spring rises to 28° fahrenheit, it becomes heavier
than the colder water and sinks, bringing to the surface a
supply of fresh water containing phosphate. This is followed
by an outburst of plankton growth limited only by the min-
erals available.

If the autocatalytic production of science is limited by some
factor necessary to it, it will accelerate until that factor be-
comes exhausted and then settle down to progress at a rate
dependent upon the supply of the factor. Up to the present,
no such limiting factor for the production of scientific knowl-
edge is apparent.

As the production of new knowledge and of new inventions
goes on, the conditions under which we live change, and we
have to adjust our lives to meet the changing conditions.
Sometimes adjustment is delayed either because the need for
it is not realized or because some group having power in the
society resists any adjustment. Then, when the adjustment
comes, it is violent. Our efforts should be directed, there-
fore, so that we can adjust our social conditions continuously
as the advance of science makes changes necessary, and so that
we recognize that the world today is a changing world and
not the relatively static world of the past.

The realization of the need for adjustment has led many
thinkers to the conclusion that the method of adjustment is
simple, that all that is required is to plan changes in our social
and economic systems to meet the advances of science. It is
believed that by planning we can avoid the difficulties and
disasters that afflict us in the absence of a central planning
organization. This goes so far in some circles that it is even
proposed to plan scientific discovery, but it is equally impos-
sible to plan in detail the economic future of a society. The
reason is the same. We do not know what discoveries are

THE PATH OF SCIENCE 229

possible; we do not know what will happen to our economics
in the near future; nobody knows.

It is not even possible to plan the whole conduct of a war,
at least if the war is to be won. There is little doubt that the
German and the Japanese staffs had complete plans for the
war that they have just lost. Those who defeated them, of
course, planned their operations, their supplies, and their
production. But these plans were based on fundamental prin-
ciples and were subject to instant change as the conditions of
the struggle changed. For this reason, prophesies as to the
course of the war had no validity; and an excellent lesson in
the weakness of human prevision can be obtained by reading
any book written between 1930 and 1945 that deals with the
probable course of the struggle between Germany or Japan
and their opponents. In politics and economics, the lesson is
the same: No one foresaw the Great Depression, the long-
continued New Deal administration in the United States, or
even such an isolated event as the fall from power of Winston
Churchill at the end of the European War.*

The progressive adjustment of social organization to meet
the rapid changes produced by the development of science
and technology cannot be determined by the direct transfer
of the techniques used in the physical and natural sciences.
As von Hayek points out, there are great differences between
the methods of the physical sciences and those of the social
sciences.f The scientist confronted with the problems of
sociology tends to imagine a theoretical society that will
follow the principles of physical science and which he can
therefore understand. This is clearly marked in the social
philosophy of Comte and Saint-Simon and in the suggestions
of the "technocrats" and of J. D. Bernal and J. G. Crowther
with their idea of "frustration" (Chapter III, page 62).

* H. B. Phillips, "On the Nature of Progress," American Scientist,
253 (1945).

■f F. A. von Hayek, "Scientism and the Study of Society," Economica,
N.S., 10, 39 (1943).

230 THE PATH OF SCIENCE

This application of the methods of physical science to the
study of society has been extended to history, so that those
who believed that a cyclic pattern could be discerned in his-
tory have desired or have been urged to "verify" their theory
by relating it to the present course of events or even by
prophesying the future. If the prophecies were confirmed,
the theory would be "verified," just as the reappearance of
Halley's comet confirmed the calculations of that great as-
tronomer. This is, of course, absurd; we know nothing of the
future, and the actors in the drama of history cannot possibly
understand the part that they themselves play in that drama.
This is true in fact, and it is also true even if we assume that,
when viewed from the standpoint of the future, the present
happenings will fall into a definite pattern. If we are pre-
pared to accept provisionally Petrie's cyclic theory (which can
only be justified strictly for art), a glance at Figure 1 (Chapter
II, page 32) will show that according to Petrie the present
corresponds to the end of the medieval cycle, while the modi-
fication suggested in Figure 2 places the present at the rising
stage of a modern cycle. Which is right cannot be deter-
mined for several hundred years even if the cycles continue
unperturbed by the unprecedented rise of science.

While the techniques of the physical sciences cannot be
transferred to the field of sociology, the scientific method it-
self can and must be used for the study of the structure of
society, its reaction to changing conditions, and the adjust-
ments required to enable it to retain stability as those condi-
tions change. An example of the application of the scientific
method to a primitive society is Malinowski's * study of the
social organization of the Trobriand islanders, which de-
pends upon the elaborate ceremonial trading system known
as the kula. A scientific study of modern industrial society
by T. N. Whitehead f is based to some extent upon field

* B. Malinowski, Argonauts of the Western Pacific, London, Rout-
ledge, 1922.

f T. N. Whitehead, Leadership in a Free Society, Cambridge, Harvard
University Press, 1936.

THE PATH OF SCIENCE 231

Studies made by the Western Electric Company in their fac-
tories. Whitehead points out that any group in society en-
deavors to insure its own survival, and that if changes are to
be acceptable they must originate within the group, prefer-
ably as from the established leader of the group. Thus the
conservative forces of society can be overcome by evolution
from within but they will oppose changes from without. The
trade union movements or the co-operative movements are
based upon the support of the individual members, many of
whom have been active in their development. In the same
way, a new religion makes rapid headway as a spontaneous
movement among the people, only to be resisted to the death
when its followers attempt to impose it upon others. Modern
society, however, has an economy based upon machine in-
dustry, and this industry is engaged in continual never-ending
change controlled by relatively logical, scientific thinking.
The result has been an increasing clash between the con-
servative instincts of the various groups of society and the
interests of the industrial leaders whose operations imperil
the continuance of those social groups.

As Whitehead says, it is impossible to resist the changes pro-
duced by the impact of technology even if such a resistance
were desirable. "So the next stage in the progress of an in-
dustrial society is surely to increase the range of systematic
thinking to include not only the technological processes but
also the social processes which hold men together." *

Twenty-five years ago, scientists were believed by the lay
public to be impractical, absent-minded people devoid of
administrative ability or common sense. Today public opin-
ion has swung to the opposite extreme, and it is even urged
that men trained in the methods of scientific research should
enter political life and endeavor to obtain a controlling posi-
tion in the administration of the commonwealth. As Bernal
says, "This solution suffers from two radical objections: first,
that no one can think of any way of transferring control into

* T. N. Whitehead, loc. cit., p. 84,

232 THE PATH OF SCIENCE

their hands; and, second, that most existing scientists are
manifestly totally unfitted to exercise such control." *

There are, indeed, certain characteristics of scientific think-
ing that make it difficult for scientists to operate in the po-
litical sphere. The age-old foe of the scientific method is
authority, and for a scientist to accept authority is to abandon
his faith. But an almost equally objectionable idea to the
scientific mind is that a decision should be made under the
influence of emotion, and in politics emotion plays a very
great part. In most political matters we do not think; we
feel. One who claimed to know him praised a certain na-
tional statesman, whereupon his listener reminded him that
though the statesman might be the wisest and noblest of man-
kind, he was yet a man and not a god. When, a few years
later, the eulogist had changed his political views, he was
reminded that the statesman might be the vilest and basest
of mankind, but he was a man and not a devil.

The cleavage in intellectual outlook and mental habits be-
tween the political leader and the scientist, the engineer,
or, for that matter, the industrialist is a very real and funda-
mental one and is by no means to be dismissed summarily.
It is common for scientists and industrialists to discuss the
methods of the politician as if he were either merely stupid
or deliberately wicked, f while the views of the political ex-
pert on the "intellectuals" are often scornful in the extreme.

As long as men's actions are controlled by their emotions,
an objective thinker who discusses every proposition without
emotion can have no part in modern political life, since a
politician must understand the effect of emotional thought
and must be prepared to utilize emotional appeal if he is to

* Bernal, The Social Function of Science, p. 398.

•f An antidote for this error can be found in F. W. Oliver's The End-
less Adventure (London, Macmillan and Co., 1930), The section "Some
Modern Dilemmas" should be of particular value to those prone to
facile criticism, while that "In Praise of Politicians" presents an excel-
lent picture of the debt we owe to those who govern us. See also "The
Magnitude of the Task of the Politician," F. M. Davenport, Harvard
Business Review, III. 468 (1933).

THE PATH OF SCIENCE 233

obtain popular support. A successful political leader must
tend, therefore, either to believe his own emotional appeal
or to become a cynic and to some extent a hypocrite if he
exerts that appeal without belief. It is this difficulty that
makes even the greatest democratic leaders seem insincere in
many of their actions. The appeal to emotion is unavoidable
if popular sanction is to be obtained, and yet their critics and
often they themselves in retrospect feel that appeal to be false
and unwarranted. For this reason alone the political arena
would seem to be unsuitable for the scientific man, and those
who believe most fully in the value of the scientific spirit
should be prepared to understand and sympathize with
leaders who must obtain general popular approval for their
actions.

In practice the adoption of political methods controlled by
pure reason could only succeed if they involved a dictatorship
and the rule of the majority of the people by a small minority.
A realization of this is evident in some of the writings of those
scientists who advocate planning.* J. G. Crowther says that
"in crises the possession of power is more important than the
cultivation of intellectual freedom." f Crowther has evi-
dently forgotten Lord Acton's dictum based on the saying
of William Pitt: "Power corrupts, and absolute power cor-
rupts absolutely."

At the present time, therefore, it seems that the many at-
tempts to frame a scientific theory that could guide political
action have been wholly unsuccessful. Political action, never-
theless, need not be arbitrary; the long-established funda-
mental principles remain that have been available to guide
human action through the ages. Truth and justice, mercy
to the weak, and understanding for the erring are principles
that require no formal justification. These are not the

* For a full discussion of planning in relation to science, see J. R.
Baker, Science and the Planned State, London, George Allen 8: Unwin,

1945.

f J. G. Crowther, The Social Relations of Science, p. 331, New York,
The Macmillan Co., 1941.

234 THE PATH OF SCIENCE

principles of science; they relate to spiritual rather than
natural laws. Nevertheless, the study of the phenomena of
society and the reactions of human beings to their social and
economic environment, if pursued in accordance with the
fundamental principles of science, will lead to a more gen-
eralized knowledge of the subject and eventually to methods
that can be applied in practice.

If the present system of government cannot change to meet
the requirements of the changing world, it must inevitably
give way to other systems. That this is so is the claim of
many leaders of political thought. But only a few years ago
it seemed impossible that industry should ever be organized
to use scientific methods. The industries of the last century
were, with few exceptions, utterly remote from the methods
of thought current in the laboratories of the universities and
were controlled largely by * 'self-made" autocrats. Within our
lifetimes all that has changed, and the leaders of our modern
industries are often technically trained experts, completely
removed from their predecessors as to their outlook and
habits of thought. In order to attain a similar result in the
field of politics, we need no revolution; we require only an
orderly evolution. As Janssen says, "There are very few
difficulties that cannot be surmounted by a will strong enough
or by study sufficiently profound." *

To effect this orderly change, we must improve the meth-
ods of thinking of the public so that they will select suitable
governors and then will require from them real leadership
and accurate thought. It is both our right and our duty to
select for ourselves those who govern us, and the necessary
changes can be effected by the proper exercise of that right
and duty. The art of government is exceedingly difficult, and
it is of the utmost importance, especially in times of transition

* In reference to his establishment of an observatory on the summit
of Mont Blanc in spite of his lameness. R. A. Gregory, Discovery or
The Spirit and Service of Science, p. 67, London, Macmillan and Co.,
Ltd., 1916.

THE PATH OF SCIENCE 235

such as the present, that the men chosen as administrators
should be selected with the utmost care.

The selection of the best methods of procedure in govern-
ment, as in science, depends eventually upon judgment, and
judgment depends upon the natural capacity of the judge
and on his training and experience. In any judgment there
will be error, and errors will occur in accordance with the
laws of probability. The judgment will be better as the
probable error is smaller, but there will always be some error.
The administrator, moreover, will suffer from bias. If he is
sufficiently objective in mind and sufficiently experienced, he
will recognize that and will attempt to make a correction for
it just as we correct precision measurements for the "personal
equation." We should, therefore, select our methods of gov-
ernment so that there is a maximum chance of arriving at
the best judgment, a minimum opportunity for bias, and a
probability that the best judgment that can be arrived at will
be applied.

In so far as our present methods do not meet these require-
ments, they should be changed. The most important matter,
however, is that we must be prepared to seek out specifically
the best men that we have for the functions of government—
not always the best in ability but often the best in character,
since a man might have first-class judgment and yet be so
biased by his ambitions that his decisions would be affected.

In addition to selecting the most suitable leaders, however,
the public must be willing to accept their leadership, to value
the expression of intelligent thought, and to discount all
appeals to emotion and to sectional interests. As Sir Ronald
Ross says:

We must not accept any speculations merely because
they now appear pleasant, flattering, or ennobling to us.
We must be content to creep upwards step by step, plant-
ing each foot on the firmest finding of the moment, using
the compass and such other instruments as we have, observ-
ing without either despair or contempt the clouds and
precipices above and beneath us. Especially our duty at

236 THE PATH OF SCIENCE

present is to better our present foothold; to investigate;
to comprehend the forces of nature; to set our State ration-
ally in order; to stamp down disease in body, mind, and
government; to lighten the monstrous misery of our fellows,
not by windy dogmas, but by calm science.*

* R. A. Gregory, op. cit., p. 233.

INDEX

Abbe, Ernst, 217
Abderhalden, E., 130
Academic dcs Sciences, 85, 86
Academy of Agricultural Science,

183
Accademia del Cimento, 85
Acetic anhydride, 128
Acetylene, 125
Achromatism, 98
Acton, Lord, 233
Adams, Brooks, 72
Agricola, 77
Agriculture, 26
Alaric, 27
Alchemy, 119
Alembert, Jean d', 92
Alexandria, 72, 88, 144
Alexandrian school, 67
Aliphatic chemistry, 125
Alkaloids, 130
Alpha particles, 111
Alpha rays, 136
American Philosophical Society,

86, 87
Amici, Giovanni, 157
Ampere, A. M., 104
Anatomy, 78, 144, 145
Anaximander, 70
Andromeda nebulae, 117
Animal colonies, 178
Animals, respiration of, 152
Anode rays, 108
Anthrax, 166
"Anticipations," 174
Arabic philosophy, 76
Arabic translations, 76
Arabs, settling of, 38

Archaeology and history, 17, 18

Archimedes, 67, 72

Argon, 116, 134

Aristarchus, 72

Aristophanes, 95

Aristotle, 71, 72, 74, 75, 76, 78,

79, 80, 88, 95, 144, 226
Aristotle's elements. 93
Armour Research Foundation, 216
Aromatic chemistry, 125
Arrhenius, Svante, 131, 133
Art, cycles of, 39

development of, 21

introduction of, 25

modern, 39
Aston, F. W., 108, 138, 177
Astrology, 41
Astronomer Royal, 176
Astronomy, 41, 88, 115, 116
Astrophysics, 117
Atlantis, New, 82
Atom, Bohr-Rutherford, 112, 137,
140

Rutherford, 111, 137
Atomic bombs, 143
Atomic nuclei, 140

disintegration of, 141, 142, 143

fission of, 142
Atomic numbers, 137
Atomic structure, 137, 138
Atomic theory, 93, 121
Atomic weights, 138
Attila, 27

Augustine, St., 5, 74
Aurelius, Marcus, 4
Authority, doctrine of, 75

237

23S

INDEX

Authority and scientific method,

232
Autocatalytic reactions, 227, 228
Avogadro, A., 122

Bachmann (Rivinus), 147
Bacon, Francis, 3, 6, 58, 72, 74, 79,

80, 81, 83, 226
Bacteria, 166
Bacteriology, 167
Baer, K. I. von, 149, 151
Baeyer, Adolph von, 129
Baker, John R., 80, 126, 198, 233
Bassi, Agostino, 166
Battelle Memorial Institute, 215
Bauhin, Kaspar, 147
Beard, C. A., 13
Becker, J. J., 120
Becquerel, H., 135
Bell, Alexander, 175
Bell Telephone Company, 175, 207
Beneden, Edouard van, 159
Bensley, R. R., 157
Benzene, 125, 126
Berlin Academy, 86
Bernal, J. D., 62, 63, 199, 200, 229,

231,232
Berzelius, J. J., 121, 122, 124, 131,

166
Beta rays, 136
Bichat, N. F. X., 153
Biology, analogy with cycles, 37

development of, 144
Birge, R., 139
Black, Joseph, 93, 152
Blood, circulation of, 146
Bohr, Niels, 111, 112, 137
Boltzmann, L., 93, 95
Bonnet, Charles, 150
Boullay, P., 124
Boulting, A. S., 20
Boyle, Robert, 55, 67, 83, 152
Brahe, Tycho, 90, 91, 96, 117
Brandeis, L., 204

Breasted, J. H., 66, 70
Britain, destruction of Roman cul-
ture in, 3
Broglie, Louis de, 56, 113
Bronsted, J. N., 133
Brown, Robert, 154
Brunner, John, 217
Buckley, Charles E., 198, 199
Buffon, Georges de, 148
Bunsen, Robert, 116, 124
Bureau of Standards, 176
Bury, J. B., 6

Bush, Vannevar, 184, 198, 199
Byzantine art, 33

Cabot, Philip, 9, 16

Caloric, 93

Calvin, J., 74

Camerarius, 151

Capitalism, growth of, 77

Carnegie Corporation, 176

Carnegie Institution, 176

Carnot, N. L. S., 94

Carroll, Lewis, 68

Catalysis, 131

Cathode rays, 105

Catholic struggle in England, 20

Causation, realization of, 225

Cavendish laboratory, 180, 182

Cell structure, 153, 155

Cell theory, 145, 155, 157, 164

Cells, differentiation of, 172

nuclear division in, 155

respiration of, 170
Cesalpini, Andreas, 146
Chadwick, J., 138
Changes, 10, 12, 14, 15, 41
Characteristic curve, photographic,

179
Characters, acquired, 148
Chemical analysis, 122
Chemical apparatus, 178
Chemical formulae, 121
Chemical ideas, growth of, 119

INDEX

239

Chemical Physics, Institute of,

Leningrad, 184
Chemical structure, 125
Chemical symbols, 121
Chemical synthesis, 122

natural compounds, 129
Chemicals, aliphatic, 125

aromatic, 125

synthetic organic, 122 ff., 178
Chemistry, 41

apparatus for, 119

development of, 119

organic materials for, 119

organic synthesis, 123

physical, 130

physiological, 129, 178
Childe, Gordon, 17, 18
Christianity, astronomical doc-
trines of, 79

effect on science, 74, 75
Christianity and philosophy of his-
tory, 5
Chromatic aberration, 97
Chromosomes, 158, 159, 160, 161
Civilization, conditioned by migra-
tion, 36

cycles of, 29

history of, 225

progress of, 21

revolutions of, 28
Cockroft, J. D., 141
Coincidence observations, 51
Colbert, J. B., 85
Collingwood, R. C, 8, 9, 33
Color vision, 97
Combustion, principle of, 120
Common sense, 55, 56
Communication in ancient times,

18
Comte, Auguste, 7, 116, 229
Conant, J. B., 198
Constantinople, fall of, 19
Constructs, 56
Cook, Captain, 163

Coolidge, ^V. D., 110
Copernicus, 70, 78, 79, 90
Cosmology, 90

Copernican, 91

early, 88
Couper, A. S., 125, 139
Crafts, J. AI., 127
Crawford, O. G. S., 37, 38
Crookes, William, 105, 106
Crowther, J. G., 183, 229, 233
Cryogenic laboratories, 177
Curie, Madame, 135, 136
Curie, P., 135
Cuvier, G., 147
Cyclotron, 141, 177
Cytochrome, 170
Cytology, 145, 153, 155

Dalton, J., 93

Daniel, G. E., 23

Darwin, Charles, 53, 145, 148, 156,

162, 163, 164, 165
Darwin, Erasmus, 148
Data, sense, 56
Davaine, Casimir, 166, 167
Davenport, F. M., 232
Davisson, C. J., 113
Davy, H., 93, 103
Debye, P., 133
De Forest, Lee, 109
Democritus, 70
Descartes, Rene, 6, 58, 61, 79, 80,

96
Deuterium, 139
Diffraction, 98, 99, 100
Disintegration, social, 10
Dispersion, 97
Dodgson, Charles L., 68
Doppler, Christian, 118
Doulton, John, 121
Dreisch, Hans, 171
Drosophila, 160, 161, 181
Dujardin, Felix, 154
Dumas, Jean, 124

240

INDEX

Duncan, R. K., 214
Dunsheath, P., 204
Dye industry and research, 175
Dynamo, 104

Eastman, George, 202
Eastman Kodak Company, 207, 208
(See Kodak Research Labo-
ratories)
Eberth, C. J., 167
Ecclesiastics and universities, 173
Ecology, 163, 164
Economics and politics, foresight

in, 228
Edison, Thomas A., 44, 61, 62, 109
Edison effect, 44
Eggs, fertilization of, 158, 159

of mammals, 149
Egypt, art in, 36

craftsmen in, 68

Eighteenth Dynasty, 28

Fourth Dynasty, 27, 28, 30, 37

history of, 27, 30

instrumental equipment in, 18

Middle Kingdom, 28, 30, 37

New Kingdom, 30, 37

Old Kingdom, 27, 28, 30, 226

prehistoric dating of, 25

Twelfth Dynasty, 28, 30, 37
Einstein, Albert, 56, 94, 113, 114,

115, 142
Electric arc lamp, 103
Electric battery, 103
Electric light, 104
Electric motor, 104
Electrical engineering, 104
Electricity, alternating current, 104

conduction of, 102
through gases, 105

current, 103

early history, 102

induction of, 102

nature of, 104

static, 103

Electricity, technology of, 44
Electrolytes, 133
Electrolytic dissociation, 133
Electromagnetism, early, 103
Electron microscope, 113, 168
Electronic tubes, 109
Electronics, 109
Electrons, 108, 109, 137

diffraction of, 113
Electrons and waves, 113
Elements, chemical, classification

of, 133, 134
Embryology, 149
Emotion and politics, 232
Empedocles, 71
Energy, conservation of, 94

radioactive, 140

transformation of, 94
Engineering, progress in, 43
Enriques, 56
Entropy, 94, 95
Enzymes, 130

Epicurean philosophy, 72, 73
Epigenesis, 150
Eratosthenes, 72
Essex, Earl of, 80
Ether, 99
Euclid, 72
Euler, L., 92
Evans, Joan, 226
Evelyn, John, 83
Evolution, 145, 148, 162, 165

Facts, classification of, 44, 49

collection of, 81

observation of, 49, 53

observers of, 49

selection of, 52
Facts and theories, 54
Faraday, Michael, 20, 54, 104, 105,

125, 133
Fellowships, industrial, 214
Fermat, Pierre de, 96, 99

INDEX

241

Fermat's law, 115
Ferments, 130

Ferns, reproduction of, 158
Fertilization, of eggs, 158, 159

of plants, 157
Feudal system, collapse of. 11, 77
Field, general theory of, 115
Fischer, Emil, 129, 130
Fission of atomic nuclei, 142
Fleming, J. A., 44, 109
Flint, 23, 24

technology of, 42
Flowers, function of, 151
Fol, Hermann, 158
Foresight, 229
Fowler, Ralph, 56
France, Anatole, 19
Frank, Tenney, 39
Frankland, E., 127
Franklin, Benjamin, 86, 103
Fraunhofer, J. von, 98, 116
Frazer, J. G., 46, 47
Fresnel, Augustin, 100, 101, 113
Friction, heat produced by, 93
Friedel, C, 127
Frustration, 62, 63, 229

Galen, 73, 76, 78, 144

Galileo, 18, 61, 67, 78, 79, 85, 88,

89, 96, 119
Galvani, L., 103
Gamma rays, 136
Gassiot, J., 105
Geissler, Heinrich, 105
Genera, 147

General Electric Company, 207
Generation, spontaneous, 166
Genes, 160, 165
Genetics, 181

Geophysical Laboratory, 177, 180
George, W. H., 49, 50, 52, 55
Gerhardt, C. F., 124
Germer, L. H., 113
Gibbs, Willard, 95, 131, 132, 199

Gilbert, William, 81, 102

Glands, 168

Glass, optical, 98

Government, the art of, 234, 235

Grant, Joan, 18

Gravitation, Newton's law of, 92

Gray, Stephen, 102

Greece, craftsmen in, 68

cycles in, 33

dark period in, 3

history in, 3

medicine in, 68

philosophers in, 70

philosophy in, 4

science in, 67, 70
Greek books translated into Ara-
bic, 76
Greek education, 3
Greek philosophers, 68
Greek science, 226
Greenwich observatory, 176
Grew, Nehemiah, 151, 153
Grid tubes, 110
Grignard reaction, 127
Grijns, G., 169
Grimaldi, Francesco, 98, 100
Growth, processes of. 172
Guldberg, C. M., 131
Gutenberg, J., 20

Hales, Stephen, 151
Halley, E., 69, 84, 85
Hamilton, W. B., 55, 99, 113
Hamm, 148

Harvey, William, 146, 149
Hatshepsut's temple, 31
Havens, Raymond Dexter, 39
Hayek, F. A. von, 1, 2, 62, 229
Heat, 93, 95
Hebrew scriptures, 75
Heisenberg, W., 113
Helium, 116. 134
Helmont. J. B. van, 151
Hemoglobin, 169

242

INDEX

Henry, Joseph, 104
Heraclitus, 70
Heredity, 159
Herodotus, 28
Hertwig, Oscar, 159
Hertz, H. R., 101, 106
Hill, A. v., 15
Hipparchus, 72
Hippocrates, 68, 70, 73
Histochemistry, 153
Histology, 153
History, 65

classical cycle of, 30, 33, 37

cycles in, 2, 4, 7, 8, 9, 27, 31,
33, 35, 36, 40
duration of, 31

events of, not understood, 19

helix of, 173,225

la^vs of, 2

natural, 164

perspective, distortion in, 18, 19

principles of, 1, 27

science of, 2

theory of, cyclic, 7, 39, 230
helical, 40, 173

written, 17
History and archaeology, 17, 18
History and Christianity, 5
History and physical science, 230
Hittorf, J. W., 105, 106
Hoff, J. H. van't, 131, 133
Hofmann, A. W. von, 122, 123, 175
Hofmeister, Wilhelm, 158
Hooke, Robert, 85, 98, 153
Hopkins, Frederic, 169
Hoppe-Seyler, F., 169, 170, 171
Hormones, 130, 168
Huckel, E., 133
Humanism and science, 16
Humanists, early, 75
Huxley, Leonard, 53
Huxley, T. H., 53, 64, 174
Huygens, Christiaan, 86, 99
Hybridization, 148

Hydra, 150

Hydrogen isotopes, 139
Hyksos, 28, 30, 37
Hypotheses, 54

Ice, melting of, 93
Imhotep, 65

Imperial Chemical Industries, 217
India, 15

Inductive reasoning, 81
Industrial research, application of,
209

control of, 220

early days, 203

small industry, 211. 217

United Kingdom, 204
Industrial research laboratories,
classification of, 204, 205

co-operation with, 210

development, 205

function of, 202

fundamental, 205, 206

number, 203

origin of, 208, 209

plant, 205

position in organization, 208,
209

size, 204
Industrial society, 230, 231
Industry, application of science to,
202

scientific control of, 234
Ingenhousz, Jan, 151
Inquisition and Galileo, 79
Institute, Optical, Leningrad, 184
Institute of Chemical Physics, Len-
ingrad, 184
Institute of Physical Chemistry,

Moscow, 184
Institute of Physical Problems, 184
Institutes, research, 177
Interference of light, 99, 100
Invention, 43

INDEX

243

Inventions, development of, 194

major, 23
Inventors, 61
Ions, 133
Isomers, 127
Isotopes, 109, 138

chemicals made with, 178

neon, 108

uranium, 142, 143

Janssen, Jules, 116, 234

Jeans, Sir James, 84

Joffe, 184

Joule, J. P., 94

Junto Society, 86

Jupiter, satellites of, 79, 99

Jussieu, A. de, 147

Kaempffert, Waldemar, 199

Kaldor, N., 204

Kant, Emmanuel, 6, 148

Kapitza, Peter, 181, 184, 189

Keilin, D., 170

Keith, Sir Arthur, 37

Kekule, August, 124, 125, 126, 127,

139
Kelvin, Lord, 61, 62
Kendall, May, 53
Kepler, J., 58, 81, 90, 91
Kepler's laws, 91, 92, 96
Kirchhoff, Gustav, 116
Koch, Robert, 167
Kodak Research Laboratories, 183
Koellicker, Rudolf, 155
Koelreuter, Joseph, 148, 151
Koerner, W., 127
Kula, 230

Lacy, W. A., 144

Lagrange, J. L., 92

Lamarck, Jean de, 148

Languages, classical, 3

Langmuir, Irving, 140

Laplace, P. S., de, 92, 93, 152, 153

Laue, Max von, 111

Laurent, A., 124

Lavoisier, A. L., 93, 120, 121, 152,

153, 169
Law, scientific, 57, 58
Laws of history, 2
Laws of motion, 89
Lawrence, E. O., 141, 177
Leaders, selection of, 235
Leadership in free society, 230
Leaves, function of, 151
Leeuwenhoek, Anton van, 153
Leibniz, G. W. von, 84, 86
Lenard, P., 106
Lenses, 95, 96
Leucippus, 70
Lewis, G. N., 139, 140
Liaison officer, scientific, 219
Liebig, Justus von, 122, 123, 124,

127, 129, 169
Light, corpuscles of, 98, 99

electromagnetic theory of, 101

interference of, 100

polarization of, 101

rays of, 99

velocity of, 99

waves of, 99, 100
Linnaeus, 147, 162
Literature, development of, 22

modern, 39
Little, A. D., 66
Lockyer, Norman, 116
Louis XIV, 85
Lucretius, 5, 73, 121
Lyonet, 149
Lysenko, T. D., 183

MacMunn, C. A., 170
Magic, 45, 46, 47
Magic and religion, 48
Magnet, discovery of, 102
Malinowski, B., 47, 48, 230
Malpighi, Marcello, 153
Malthus, T., 148, 162

244

INDEX

Malus, E. L., 100

Margenau, H., 56

Marx, K., 82, 226

Mass, definition of, 89

Mass action, law of, 131

Mass energy relation, 115

Mass spectrograph, 108, 139

Maxwell, J. Clerk, 101, 113

Mayer, Julius, 94

Mayow, John, 152

Mechanics, beginnings of, 78, 88

laws of, 92
Medici brothers, 85
Mees, C. E. K., 186
Mellon Institute, 176, 214, 215
Mendel, Gregor, 63, 148, 159, 160,

161, 162, 165
Mendeleev, D. I., 134
Mendelism, 165
Mensuration, early, 88
Menzel, D., 139
Mercury, perihelion of, 114
Metallurgy, 41
Meteorology, science of, 45
Michelson, Albert, 113
Michelson-Morley experiment, 114
Microincineration, 156
Micro-organisms, 166
Microscope, invented, 78, 83
Middle Ages, 67
Midwest Research Institute, 216
Migration, effect on civilization, 36
Mirbel, 153
Mohl, Hugo, 154, 155
Molecules, 122

motion of, 94
Monasteries, 74
Mond, Ludwig, 217
Moon observed by Galileo, 79
Morgan, T. H., 160, 161, 181
Morgan, William, 104, 106
Morley, Edward, 114
Morphology, 156
Moseley, H. G. J., 137, 138

Motion, laws of, 88, 89, 92

Mount Wilson Observatory, 177

Miiller, Johannes, 166

Muller, H. J., 165

Museum at Alexandria, Egypt, 144

Mutation, 165

Niigeli, Karl, 155, 158

National Physical Laboratory, 176

National Research Foundation,

185
Natural selection, 145, 165
Nature, existence of, 58
Nebulae, 117, 118

Andromeda, 117
Needham, J., 38, 149
Nela Park Laboratory, 180
Neolithic period, 23, 24, 40
Neon isotopes, 108
Neoplatonism, 74
Neptune, discovery of, 116
Nernst, W., 131

Newton, Sir Isaac, 20, 52, 55, 58,
61, 67, 69, 72, 84, 85, 86,
90, 91, 92, 96, 97, 98, 100,
119, 138

laws of, 89, 92
Nezv York Times, 198, 199
Nordenskiold, E., 144
Nova, observation of, 78
Nuclear physics, 140, 180
Nuclei of atoms, 140
Nucleus, cell, 154
Nuffield College, Oxford, 211

report of, 217
Nutrition, 169
Nutting, P. G., 210

Observations, 51
Observer, interest of, 52
Oersted, H. C., 103, 104
Oken, Lorenz, 153
Oliver, F. W., 232
Onnes, Kamerlingh, 181

INDEX

245

Optical glass, 98

Optical Institute, Leningrad, 184

Organisms, classification of, 147

Ornstein, Martha, 82, 87

Osmotic pressure, 133

Ostwald, Wilhelm, 131, 132

Oxygen, 121

Painter, T. S., 162

Paleolithic period, 23, 40

Paleontology, 147

Parallax of stars, 91

Pasteur, Louis, 166, 167

Patents, development of, 194

Paterson, C. C, 202

Pendulum, 99

Periodic table, 134

Perkin, W. H., 123, 175

Petrie, W. M. F., 9, 24, 25, 28,
29, 30, 31, 33, 35, 37, 38,
230

Petroleum, chemicals from, 128

Petroleum industry, research in,
217

Phase rule, 132

Phillips, H. B., 19, 200, 229

Philosophical Transactions of the
Royal Society, 84

Philosophy, Arabic, 76
Greek, 68
Stoic, 72

Phlogiston, 120

Photographic research, 179

Photographs, observation of, 50

Photography, science of, 43
technology of, 43

Photo tubes, 110

Phvsical Chemistry, Institute of,
Moscow, 184

Physical methods and social sci-
ences, 229

Physico-technical Institute, Khar-
kov, 184
Leningrad, 184

Physics, growth of ideas, 88
nuclear, 140
origin of, 88

Physiological chemistry, 178

Physiology, 171

Pilate, Pontius, 19

Pile, atomic, 143

Pitchblende, 135

Pitt, William, 233

Planck, Max, 55, 112, 113

Planets, orbits of, 91

Plankton, production of, 228

Planning, industrial research, 6, 7,
8, 195, 221 ff.
scientific research, 195

public discussion of, 198
in society, 228, 229
in war, 229

Plants, fertilization of, 157
reproduction of, 158
respiration of, 151

Plastics, 129

Plato, 4, 7, 9, 68, 71, 72, 74, 95,
226

Pliny, 73

Plutonium, 143

Polanyi, M., 49

Polarization of light, 100, 101

Political action, fundamental prin-
ciples of, 233, 234

Political economy, 226

Political methods and pure reason,
233

Politician, task of, 232

Politicians as seen by scientists, 232

Politics and economics, foresight
in, 229

Politics and emotion, 232

Politics and science, 226

Pollination, 151

Polonium, 136

Polybius, 7, 9

Polymerization, 128, 129

Pottery, 25, 26

246

INDEX

Pouchet, Felix, 166
Preformation, 150
Priestley, Joseph, 120, 151
Pringsheim, Nathaniel, 157
Printing, its importance in science,

69
Printing early books, 76
Progress, 17

in engineering, 43

idea of, 6, 13

in material aspects, 11
Progress and science, 21, 42
Progress and technology, 43
Project system of research control,

220
Prophets, 47
Protein, 156

Proteins, chemistry of, 130
Proton, 138
Protoplasm, 154
Proust, J. L., 121
Ptolemy, 72

Ptolemy (astronomer), 90
Purine derivatives, 129
Purkinje, Johannes, 154
P)Tamid builders, 27, 30, 226
Pyramids, 43
Pythagoras, 4, 71, 80

Quadrants, use of, 90
Quantum mechanics, 113
Quantum theory, 112, 113

Rabies, virus of, 168

Radicals, 123, 124

Radioactive energy, 140

Radioactivity, 111

Radium, 136

Ramsay, William, 116, 134, 182

Raspail, F. B., 153, 155, 156

Rayleigh, Lord, 63, 107, 119, 134

Rays, anode, 198

cathode, 105, 106, 109

light, 99

Rays, positive, 108

Reaction, 90

Reactions, autocatalytic, 227, 228

chemical rate of, 130, 131

termination of, 228
Redi, 149
Reform bill, 20
Reformation, 11
Refraction, double, 99, 101

law of, 96
Regeneration, 149
Reichsanstalt, 176
Relativity, theory of, 113, 114
Religion, 47

Christian, and authority, 75
Religion and magic, 48
Religion and natural phenomena,

47
Remlinger, P., 168
Renaissance, 77
Renold, C. G., 219
Research, applied, differentiated
from fundamental, 206
Department of Scientific and In-
dustrial, 204, 211
direction of, 189
in the electrical industry, 175
General Electric, 175
in the German chemical indus-
try, 175
industrial, 175

application of, 209
control of, 220
early days, 203
organization of, 186
origin of, 175
small industry, 211, 217
success in, 224
United Kingdom, 204
methods of, 173
organization of, 185
in the petroleum industry, 217
photographic, 179, 208

INDEX

247

Research, planning of, 195, 196,
197, 198, 221 fE.
scientific, agencies for, 181, 182
apparatus used, 177
direction of, 189
government supported, 176
organization of, 81, 195
unit of, 188
telephone, 175, 207
Research associations, British, 204,
211, 213,
functions of, 212, 213
Research department in industry,
function of, 202
growth and importance, 203
Research director, 218
for small industry, 219 ff.
training for, 219
Research institutes, 82, 83, 177, 182
support of, 193
technological, 176, 214
Research laboratories, classification
of, 179
convergent, 180
directors of, 189, 190, 191, 192,

193
divergent, 208

industrial, classification of, 204,
205
co-operation with plants, 210
development, 205
function of, 202
fundamental, 205, 206
number, 203
origin of, 208, 209
plant, 205
position in organization, 208,

209
size, 204
organization of, 186, 190
Respiration of cells, 170
of animals, 152
of plants, 151

Richardson, O., 44
Rivinus (Bachmann), 147
Rockefeller Foundation, 176
Rockefeller Institute, 176
Roentgen, Wilhclm, 106, 135, 198
Roman Empire, 37, 38

fall of, 29
Roman law, 38
Roman philosophy, 72
Rome, collapse of republic, 9

cycle of, 33
Romer, O., 99
Roozeboom, H. W. B., 132
Ross, Ronald, 235
Roux, Wilhelm, 171
Royal Society, 82, 83, 84, 85, 86

Philosophical Transactions of,
84
Ruhmkorff coil, 105
Rumford, B. T., 93
Russia, organization of research

in, 183
Russian Academy of Sciences, 183
Rutherford, Daniel, 152
Rutherford, Ernest, 111, 136, 138,

140, 141, 177, 181
Rutherford atom, 137
Rutherford-Bohr atom, 137, 140

Saint-Simon, Comte de, 229
Salomon, House of, 82
Sarton, George, 16, 21, 22, 41
Saussure, Nicolas de, 152
Scheele, Karl, 120
Schleiden, M. J., 145, 154, 155
Schroedinger, E., 113
Schwann, Theodore, 154, 155
Science, 41

application of, 182
to industry, 202, 226

applied, 62, 63, 64

development of, 57

direction of, 63

early, 70

248

INDEX

Science, effect on conditions of life,
174, 228
experimental, 4, 48
growth of, 15, 22, 65, 67
history of, 21
ideas of, 48
instruments in, 51
laws of, 58

method of, 42, 48, 59, 60, 63, 64
observations in, 57
of photography, 43
production of, limiting factor

for, 228
progress throughout history, 225

rate of, 225
publication of, 69
Science and classification of facts,

44
Science and humanism, 16
Science and meteorology, 45
Science and the Planned State, 233
Science and progress, 21, 42
Science and social conditions, 228
Science and society, 15
Science and sociology, 226
Science and superstition, 45
Science and technology, 44
Science and universities, 173
Science teaching in English uni-
versities, 68
Sciences, social, 226
Scientific discoveries, chance of

making, 197
Scientific laws, 57
Scientific Life, The 198
Scientific method, application to

problems, 225
Scientific method and authority,

232
Scientific methods and industry,

234
Scientific methods and the struc-
ture of society, 230

Scientific Research and Develop-
ment, Office of, 184
Scientific revolution, 81
Scientism, 229

Scientist, characteristics of the, 49
Scientists, in action, 49
classification of, 61
kinds of, 60

as seen by politicians, 232
Scientists and politics, 231 ff.
Sclater, P. L., 163
Sculpture, archaic age in, 31
Shapley, Harlow, 181
Silk worms, disease of, 166
Similarity in magic, 46
Singer, C, 60, 67, 73, 144
Snell, W., 96

Social conditions, improved, 12
Social conditions and science, 228
Social sciences and physical meth-
ods, 229
Society, adaptation of, 234
planning in, 228, 229
structure of and scientific
method, 230
Society and science, 15
Sociology and science, 226
Socrates, 71

Solar system, nature of, 78
Sound, reproduction of, 110
Southern Research Institute, 216
Soviet Union, philosophy of. 62
Spallanzani, L., 148, 153, 166, 169
Species, 147

origin of, 156, 162, 163
Spectacles, 95, 96
Spectra, analysis of, 177

mechanism, 112
Spectrum, 97

solar, 98
Spemann, Hans, 172
Spencer, Herbert, 7, 38, 226
Spenglcr, Oswald, 8, 9
Spermatozoa, discovery of, 148

INDEX

249

Spiral nebulae, 117, 118

Sprengel, Christian, 151

Stability of conditions, 1

Stahl, George Ernst, 120

Staining technique, 145, 153, 156

Stamp, Lord, 14

Stars, observations of, 90

Steensen, Nils, 147

Stellar composition, 116

Stine, C. M. A., 206, 207

Stoic philosophy, 72

Stoicism, 74

Strasburger, Eduard, 158

Sugars, chemistry of, 130

Superstition and science, 45

Sutton, W. S., 160

Swammerdam, Jan, 150

Swedish Empire, 27, 150

Sylvius, Aeneas, 20

Synthetic organic chemicals, 178

Technocracy, 229

Technological research institutes,

176, 214
Technology, 13, 42, 43

of ancients, 17

of electricity, 44

impact on society, 231

industrial rise of, 174
Technology and progress, 43
Technology and science, 44
Telegraph, 104
Teleology, 73
Telephone, 104
Telephone research, 179
Telescope invented, 78, 83
Thales, 68, 70, 71
Theories, 54

absurd, 55, 56

nature of, 57

postulates of, 55

verification of, 55
Theory, general field, 115

Thermodynamics, laws of, 94

Thomson, Elihu, 175

Thomson, J. J., 61, 62, 107, 109,

177, 188
Thorium, radioactivity of, 135, 137
Tobacco, mosaic, 167
Tools, 23

Trembley, Abraham, 149, 150
Trobriand society, 230
Tubes, electronic, 109, 110

photo, 110
Tutankhamen, 28, 43
Tyndall, J., 174
Types, chemical, 124

Universities, medieval, 75
Universities and ecclesiastics, 173
Universities and science, 173
Uranium, radioactivity of, 135, 137
Uranium isotopes, 142
Urea, 129

synthesis of, 155
Urey, H., 139

Valence bonds, 139

Valve tubes, 110

Vaucheria, 157

Vesalius, Andreas, 77, 81, 145, 146

Vico, 7, 9

Vinci, Leonardo da, 77, 81

Viruses, 167, 168

Vitamins, 130, 169

Vogt, W., 172

Volta, A., 103

Waage, P., 131

Wallace, A. R., 145, 148, 162, 163

Wallace's line, 163

Walton, E. T. S., 141

W^ar, foresight in, 229

Weaver, Warren, 199

Wells, H. G., 2, 51, 174

Western Electric Company, 231

250

INDEX

Westinghouse Electric Company,

207
Wharton, Thomas, 168
Whitehead, A. N., 12, 13, 226, 227
Whitehead, T. N., 230, 231
Whitney, W. R., 199
Wilhelmy, L., 130
William of Occam, 55
Williamson, A. W., 124
Willis, Thomas, 146
Wohler, Friedrich, 123, 124, 127,

129, 155
Wolff, Caspar, 150, 153, 172
^Volsey, Thomas, 12
Wolters, A. W. P., 50

Wren, Sir Christopher, 83
Writing, origin of, 26, 27, 225, 226

X-ray tubes, 110

X-rays, 110, 111, 135
diffraction of, 111
discovery of, 106, 198
emitted by elements, 137
nature of, 102, 111
producing mutation, 166

Young, Thomas, 97, 100

Zeiss Carl, 217

Zilsel, E., 57, 67, 75, 77

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