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Call No. i?3'^r/ /f ^4 ^ Accession No.% ' 


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Late Research Associate in Geography in Yale University 



Copyright, 1015, 1922, 1924-, by Yale University Press. 
Printed In the United Stales of America. 

Published, 1915. 

Second Printing, 19 16. 

Third Printing, 1919. 

Second and Enlarged Edition, 1922. 

Third Edition with Many New Chapters, \ 924. 

Third Edition, Second Printing, 193*3. 

Third Edition, Third Printing, 1935. 

Third Edition, Fourth Printing, September, 1939. 

Third Edition, Fifth Printing, April, 1945. 

Third Edition, Sixth Printing, April, 1948. 

All rights reserved. This book may not be reproduced, in 
whole or in part, in any form (except by reviewers for the 
public press), without written permission from the publishers. 


List of Illustrations vii 

Preface to First Edition xi 

Preface to Third Edition xv 

Author's Bibliography xvii 

Chapter I. Introduction 1 

Chapter II. Race or Place 30 

Chapter III. The White Man in the Tropics . . 56 

Chapter IV*. The Effect of the Seasons .... 76 
Chapter V. The Effect of Humidity and Tempera- 

Jure 109 

Chapter VI. Work and Weather 136 

Chapter VII." Health and the Atmosphere . . . 153 

Chapter VIII. Mortality, Moisture, and Variability 174 

Chapter IX. Health and Weather 194 

Chapter X: The Ideal Climate 220 

Chapter XI. The Distribution of Civilization . . 240 
Chapter XII. Vitality and Education in the United 

States 275 

Chapter XIII. The Conditions of Civilization . . 291 

Chapter XIV. The Shifting of Climatic Zones . . 315 
Chapter XV. The Pulsatory Hypothesis and Its 

Critics 335 

Chapter XVI. The Shifting Centers of Civilization . 347 
Chapter XVII. Aboriginal America and Modern Aus- 
tralia 366 


Chapter XVIII. The Climatic Hypothesis of Civiliza- 
tion 387 

Appendix 413 

Index 433 


Figure 1. The Effect of the Seasons on Factory 

Operatives in Connecticut and at Pittsburgh 84 
Figure 2a. Human Activity and the Seasons ... 92 
Figure 2b. Human Activity and the Seasons ... 93 
Figure 3. Seasonal Variations of Mental Compared 

with Physical Activity 105 

Figure 4. Relative Humidity and Work in Connecticut 112 
Figure 5. Average Weekly Temperature During the 

Summers of 1910-1913 in Connecticut . . 116 
Figure 6. Effect of the Days of the Week on Piece- 
Workers 120 

Figure 7. Variations in Daily Wages 122 

Figure 8. Human Activity and Mean Temperature . 124 
Figure 9. Growth of Wheat at Various Temperatures 129 
Figure 10. Mean Temperature and Vital Processes in 

Plants, Animals, and Man 130 

Figure 11. Human Activity and Change of Mean Tem- 
perature from Day to Day 140 

Figure 12. The Stimulus of Storms 147 

Figure 13. Seasonal Variations in Energy and Health . 154 
Figure 14. Seasonal Variations in Conceptions and 

Deaths in Japan, 1901-1910 .... 159 
Figure 15. Post-operative Death Rate at Boston in 

Relation to Humidity and Temperature . 180 
Figure 16. Relation between Deaths from Pneumonia 
and Influenza and Interdiurnal Changes of 

Temperature 184 

Figure 17. Correlation between Weather Elements and 
Daily Deaths in New York City, December 
to March 1882-1886 196 



Figure 18a. Excess or Deficiency of Death Rates in 

Months of Extreme Weather in American 

Cities, 1900-1915 206 

Figure 18b. Excess or Deficiency of Death Rates in 

Months of Extreme Weather in American 

Cities, 1900-1915 207 

Figure 19. Correction for Effect of Other Climatic 

Factors 211 

Figure 20. Excess or Deficiency of Deaths in Relation 

to Stormy Periods Lasting One Month, Two 

Months, ancLThree Months, 1900-1915 . 216 
Figure 21. Net Effect of Weather in the United States 218 
Figure 22. The Effect of Climate on Human Energy as 

Inferred from Work in Factories . . . 234 
Figure 23. The Distribution of Civilization^n Europe 257 
Figure 24. The Distribution of Civilization in Asia . 259 
Figure 25. The Distribution of Civilization in Australia 260 
Figure 26. The Distribution of Civilization in Africa 261 
Figure 27. The Distribution of Civilization in South 

America 262 

Figure 28. Civilization in North America, According 

to all Contributors 264 

Figure 29. Civilization in North America, According to 

Twenty-five Americans 265 

Figure 30. Civilization in North America, According 

to Seven British Contributors .... 268 
Figure 31. Civilization in North America, According 

to Six Germanic Europeans 269 

Figure 32. Civilization in North America, According 

to Six Latin Europeans and One Russian . 272 
Figure 33. Civilization in North America, According 

to Five Asiatics 273 

Figure 34. Climatic Energy in the United States on the 

Basis of Factory Work 276 



Figure 35. Vitality in the United States, According to 

Life Insurance Statistics 276 

Figure 36. Distribution of Climatic Health on Basis of 

Seasonal Variations in 33 Cities, 1900-1915 277 
Figure 37. Civilization in the United States . . . 277 
Figure 38. Distribution of Education in the United 

States 284 

Figure 39. Percentage of Gainfully Employed Persons 
in the United States Engaged in Manu- 
facturing, 1919 284 

Figure 40. Distribution of Climatic Energy in Europe 292 
Figure 41. Distribution of Health in Europe . . . 293 
Figure 42. Distribution of Civilization in Europe . . 293 
Figure 43. The Distribution of Human Health and 

Energy on the Basis of Climate .... 295 
Figure 44. The Distribution of Civilization . . . 295 
Figure 45. Birthplaces of Persons of Unusual Ability 

in the United States 307 

Figure 46. Changes of Climate in Western Asia and 

Growth of Trees in California . . . .318 
Figure 47. Changes of Climate in California for 2,000 

Years 321 

Figure 48. The Shifting of the Storm Belt .... 358 


THIS volume is a product of the new science of geography. 
The old geography strove primarily to produce exact maps 
of the physical features of the earth's surface. The new goes 
farther. It adds to the physical maps an almost innumerable 
series showing the distribution of plants, animals, and man, and 
of every phase of the life of these organisms. It does this, not 
as an end in itself, but for the purpose of comparing the physi- 
cal and organic maps and thus determining how far vital phe- 
nomena depend upon geographic environment. Among the things 
to be mapped, human character as expressed in civilization is 
one of the most interesting and one whose distribution most 
needs explanation. The only way to explain it is to ascertain the 
effect of each of many cooperating factors. Such matters as 
race, religion, institutions, and the influence of men of genius 
must be considered on the one hand, and geographical location, 
topography, soil, climate, and similar physical conditions on 
the other. This book sets aside the other factors, except inci- 
dentally, and confines itself to climate. In that lie both its 
strength and weakness. When the volume was first planned, I 
contemplated a discussion of all the factors and an attempt to 
assign to each its proper weight. The first friend whom I con- 
sulted advised a directly opposite course, whereby the emphasis 
should be centered upon the new climatic facts which seem to 
afford ground for a revision of some of our old estimates of the 
relation between man and his environment. In writing the book 
I have growingly felt the wisdom of that advice, and have been 
impressed with the importance of concentration upon a single 
point, even at the expense of seeming to take a one-sided view. 


If the reader feels that due weight is not given to one factor or 
another, he must remember that many unmentioned phases of 
the subject have been deliberately omitted to permit fuller 
emphasis upon the apparent connection between a stimulating 
climate and high civilization. 

The materials for this volume have been derived from a great 
variety of sources. Although personal observation and investi- 
gation are the basis of much that is here stated, still more has 
been derived from the world's general store of knowledge. Except 
in a few special cases I have not attempted to give references. 
To the general reader footnotes are not only useless, but often 
a distraction and nuisance. The careful student, on the other 
hand, cannot form a fair estimate of the hypothesis here pre- 
sented without reading previous publications in which I have 
set forth the reasons for many conclusions which are not fully 
discussed here for lack of space. These publications contain 
numerous references. Accordingly, the needs of the student will 
be met by giving a brief list of books and articles which have 
served as preliminary steps to the present volume. These publi- 
cations form a logical series with only such repetition as is 
necessary to make each a complete unit. It is scarcely necessary 
to add that the rapid growth of the subject during the past ten 
years has led to important modifications in some of the earlier 

The facts set forth in this volume have by no means been 
derived wholly from observation and reading. Not far from a 
hundred people have given direct personal assistance. They are 
so numerous that it is impossible to mention them all by name. 
Therefore it seems best not to single out any for special thanks. 
Many of my colleagues among the Yale faculty and among the 
geographers of America have gone out of their way to offer sug- 
gestions, or friendly criticisms, or to bring to my attention 
publications and facts that might have escaped my notice. 
Others connected with such organizations as the Carnegie Insti- 


tution of Washington and the United States Weather Bureau 
have placed me under obligation by the kind way in which they 
have taken a personal rather than official interest in answering 
queries and providing data. Equally great courtesy has been 
shown by officers and other members of the teaching force at 
West Point and Annapolis, and by officials connected with 
various factories, including some whose figures it has not yet 
been possible to tabulate. Another large group comprises con- 
tributors to the map of civilization, many of whom devoted to 
this work time which they could ill afford. Lastly, I owe much 
to personal friends who fall in none of the groups already speci- 
fied. I suppose that the total time given to this book by all these 
scores of people makes their contribution larger than mine. My 
chief hope is that they may feel that their kindness has not been 
wasted. To each and all I can only express my deep sense of 
gratitude, and most of all to those whose advice from the be- 
ginning has done more than anything else to keep this book true 
to a single aim. 

E. H. 
Yale University, 

New Haven, Conn., 
July, 1915. 


IN preparing the third edition of this book two circumstances 
have led to a radical revision. First, the World War has 
receded far enough into the background so that people's minds 
are once more able to concentrate upon the far-reaching prob- 
lems of science, instead of the temporary details associated with 
war. During the past three years this has led to a marked in- 
crease in the number of publications dealing with the problems 
of this book. Second, during the nine years since the first edition 
was issued many new facts have come to light which amplify 
and strengthen the general hypothesis of the effect of climate 
upon civilization. 

The present edition differs from the first in several important 
respects : 

1. In the first edition inheritance, physical environment, and 
culture were recognized as the three main factors in determining 
the distribution of civilization. Physical environment was of 
course treated fully, since it is the main subject of the book. 
Enough was also said about human culture to show that I fully 
appreciate its importance, especially as an explanation of the 
difference between aboriginal America and the Old World. In- 
heritance, however, was dismissed briefly. In the present edi- 
tion it receives a good deal of emphasis, especially in the first 
chapter, which is almost wholly new. It would be emphasized 
much more strongly were it not that in The Character of Races 
I have devoted a whole book to the problem. That book and this 
are so closely allied that neither is complete without the other. 

2. The relation of climate to health has been much discussed 
during the past nine years. Accordingly three new chapters, Vii 


to IX, have been added on this topic. They balance the three 
preceding chapters by discussing the manifold effects of cli- 
mate and weather upon man from the standpoint of disease and 
death, instead of from the standpoint of the day's work. 

3. In the first edition of Civilization and Climate I assumed 
that historians and others would be more familiar with the evi- 
dence of climatic changes during historic times than is actually 
the case. Accordingly in Chapter XIV the hypothesis of pulsa- 
tory climatic changes is more fully elaborated than formerly, 
while Chapter XV, which is new, is devoted to criticisms of that 

4. Chapters XVI and XVII are devoted to some of the main 
criticisms of the hypothesis that climate is one of the three main 
determinants of the distribution of civilization. An especially 
important new feature is a study of the white man in tropical 

5. In addition to this a large number of minor points have 
been added. Hence, although certain sections such as Chapters 
III to VI remain practically unchanged, the book as a whole has 
a distinctly new aspect. In its present form the book does not 
insist as strongly as before upon the supreme importance of 
climate, but the arguments which lead to the conclusion that 
climate ranks with racial inheritance and cultural development 
as one of the three main factors in determining the distribution 
of civilization seem much stronger than previously. 

E. H. 
New Haven, September, 1924. 


THIS list contains the titles of publications of the author 
which deal with the problems of this book. For details as 
to many points here discussed, the reader is referred to these 

(A) Books and longer articles on changes of climate and their 
effect on man: 

(1) EXPLORATIONS IN TURKESTAN. Publications 26 and 73 
of the Carnegie Institution of Washington, 1905, pp. 157-317. 

(2) THE PULSE OF ASIA. Boston, Houghton Mifflin Company, 
1907, 415 pp. 

ton Mifflin Company, 1911, 433 pp. 

ICA. Publication 192 of the Carnegie Institution of Washington, 
1914, 341 pp. 

of the Geological Society of America, vol. 25, 1914, pp. 477- 

(B) Shorter articles dealing with phases of the problem of 
climatic changes not treated under (A) : 

(6) THE BURIAL OF OLYMPIA. Geographical Journal, Lon- 
don, 1910, pp. 657-686. 

(7) THE OASIS OF KHARGA. Bulletin of the American Geo- 
graphical Society, New York, vol. 42, 1910, pp. 641-661. 

glacial Climatic Changes, Publication No. 352, Carnegie Insti- 
tution of Washington, 1924. (In press.) 

(C) Books and articles dealing with climate and civilization: 



CONDITION OF TURKEY. Journal of Race Development, Worces- 
ter, Mass., vol. 1, 1911, pp. 460-481. 

ACTER. Journal of Race Development, Worcester, Mass., vol. 2, 
1912, pp. 256-281. (Reprinted in a volume entitled JAPAN AND 
JAPANESE AMERICAN RELATIONS, edited by G. H. Blakeslee, 
New York, 1912, pp. 42-67.) 

cal Review, vol. 18, 1913, pp. 213-232. 

AMERICA. In Latin America. Clark University Addresses, 1913, 
edited by G. H. Blakeslee, pp. 360-386. 

(13) THE GEOGRAPHER AND HISTORY. The Geographical 
Journal, London, January, 1914. 

Journal of Race Development, Worcester, Mass., vol. 6, 1915, 
pp. 167-184. 

Geographical Review, vol. 1, March, 1916, pp. 192-201. 

ings of the 19th International Congress of Americanists, Wash- 
ington, 1917, pp. 150-164. 

ELEMENTS IN THE FALL OF ROME. The Quarterly Journal of 
Economics, vol. 31, February, 1917, pp. 173-208. 

(18) THE RED MAN'S CONTINENT. New Haven, 1919. 


(20) BUSINESS GEOGRAPHY. New York, 1922. 

(D) Books and articles published since the first edition of CIVI- 
LIZATION AND CLIMATE and dealing largely with the relation 
between climate and health: 

(21) WORLD POWER AND EVOLUTION. New Haven, 1919. 

GRAPHS. Modern Medicine, vol. 1, May, 1919. 


WEATHER. Ecology, vol. 1, January, 1920. 

PITALS. The Modern Hospital, vol. 14, April, 1920. 

Modern Hospital, vol. 14, May, 1920. 

EXAMPLE OF MEXICO. The Geographical Review, vol. 11, April, 

OPERATIVE DEATH RATE. American Journal of Surgery, vol. 35, 
July and October, 1921. 

IN 1918. The Scientific Monthly, vol. 17, November, 1923. 

Bulletin of the National Research Council, vol. 6, July, 1923. 

(E) Books and articles dealing with natural selection and racial 

Association of American Geographers, 1924. 

(31) THE CHARACTER OF RACES. New York, 1924. 

(F) Books dealing zvith the nature and causes of climatic 
changes : 

(32) CLIMATIC CHANGES (with S. S Visher). New Haven, 

WEATHER. New Haven, 1923. 



THE races of the earth are like trees. Each according to its 
kind brings forth the fruit known as civilization. As russet 
apples and pippins may grow from the same trunk, and as 
peaches may even be grafted on a plum tree, so the culture of 
allied races may be transferred from one to another. Yet no one 
expects pears on cherry branches, and it is useless to look for 
Slavic civilization among the Chinese. Each may borrow from 
its neighbors, but will put its own stamp upon what it obtains. 
The nature of a people's culture, like the flavor of a fruit, de- 
pends primarily upon racial inheritance, which can be changed 
only by the slow processes of biological variation and selection. 
Yet inheritance is only one of the factors in the development 
of civilization. Religion, education, government, and all of man's 
varied occupations, customs, and institutions his inherited 
culture as the anthropologists say form a second great group 
of social influences whose power seems almost immeasurable. 
They do for man what cultivation does for an orchard. One tree 
may bear a few wormy, knotty little apples scarcely fit for the 
pigs, while another of the same variety is loaded with great red- 
cheeked fruit of the most toothsome description. The reason 
for the difference is obvious. One tree grows in a grassy tangle 
of bushes with no room to develop, little chance to get sunlight, 
and scant opportunity to obtain nourishment because of the 
abundance of other plants and the poverty and thinness of the 
unfertilized soil. The other stands in the midst of a carefully 


tilled garden where it has plenty of room to expand and enjoy 
the sun, and where its roots can spread widely in a deep, mellow, 
well-fertilized soil. Moreover, one tree is burdened with dead 
wood and suckers, and infested with insects and other parasites ; 
while the other is carefully pruned, scraped, and sprayed. 

In spite of the most careful and intelligent cultivation, a tree 
of the finest variety may fail to produce good fruit. Too much 
rain or too little ; prolonged heat or constant cloudiness ; frost 
when the blossoms are opening, or violent wind and hail may all 
be disastrous. The choicest tree without water is worth less than 
the poorest where the temperature and rainfall are propitious. 
Its health is ruined, and it can bear no fruit. Here, as in the 
preceding case, the great need of the tree is health in the fullest 
and broadest sense. A good climate, good cultivation, and good 
nourishment are merely means of giving the tree perfect health 
and thus allowing the fullest development of its inheritance. 
Thus the two great factors which really determine the quality 
of the fruit are inheritance and health. The other factors, 
namely, food, climate, parasites, and cultivation, are important 
chiefly as means whereby health, or, perchance, inheritance, is 

Does the fruit known as civilization depend upon these same 
conditions? It seems to me that it does. Few would question that 
a race with a superb mental and physical inheritance and en- 
dowed with perfect health is capable of adding indefinitely to 
the cultural inheritance received from its ancestors, and thus 
may attain the highest civilization. But if that same cultural 
inheritance were given to a sickly race with a weak inheritance 
of both mind and body, there would almost surely be degenera- 
tion. Aside from biological inheritance, the main factors in 
determining health are climate, food, parasitic diseases, and a 
people's stage of culture, which corresponds to the cultivation 
of the tree. Moreover, these same four factors, through their 
potency in selecting some types for preservation and others for 


destruction, and perhaps through their power to cause muta- 
tions, are among the main agencies in determining inheritance. 
Climate stands first, not because it is the most important, but 
merely because it is the most fundamental. It is fundamental 
by reason of its vital influence upon the quantity and quality not 
only of man's food but of most of his other resources ; it plays 
a large part in determining the distribution and virulence of 
the parasites which cause the majority of diseases ; and through 
its effect upon human occupations, modes of life, and habits, it 
is one of the main determinants of culture. On the other hand, 
neither food, disease, nor culture has any appreciable effect 
upon climate, although they may modify its influence. Moreover, 
climate has a direct effect upon health in addition to its indirect 
effect through food, disease, and mode of life. Hence although 
climate may be no more important than other factors in deter- 
mining the relative degree of progress in different parts of the 
world, it is more fundamental in the sense that it is a cause 
rather than a result of the other factors. 

In studying climate it is essential to draw a sharp distinction 
between three types of influences. In the first place climate has 
a direct effect upon man's health and activity. Second, it has 
a strong indirect but immediate effect through food and other 
resources, through parasites, and through mode of life. Third, 
by its combined direct and indirect effects in the past it has 
been a strong factor some would say, the strongest in caus- 
ing migration, racial mixture, and natural selection ; and it may 
have had something to do with producing the variations which 
the biologists call mutations. Thus it has had a powerful effect 
upon inheritance. 

From the days of Aristotle to those of Montesquieu and 
Buckle, there have been good thinkers who have believed that 
the direct effect of climate is the most important factor in de- 
termining the differences between the degree of progress in vari- 
ous parts of th? earth. Others have held that wherever food is 


available for a moderately dense population and man can avoid 
diseases like tropical malaria, human culture can rise to the 
highest levels. The location of the world's great nations seems 
to them largely a matter of accident. 

The majority of people reject both of these extreme views. 
Few doubt that climate has an important relation to civilization, 
but the majority consider it less important than racial inherit- 
ance, proper food, or good institutions in the form of church, 
state, and home. We realize that a dense and progressive popula- 
tion does not live in the far North or in deserts simply because 
l 1 he difficulty of getting a living grinds men down and keeps 
them isolated. We know that the denizens of the torrid zone are 
slow and backward, and we almost universally agree that this 
is connected with the damp, steady heat. We continually give 
concrete expression to our faith in climate. Not only do we talk 
about the weather more than about any other one topic, but we 
visit the seashore or the mountains for a change of air. We go 
South in winter, and to cool places in summer. We are depressed 
by a series of cloudy days, and feel exuberant on a clear, brac- 
ing morning after a storm. Yet, in spite of this universal recog- 
lition of the importance of climate, we rarely assign to it a 
'oremost place as a condition of civilization. We point out that 
cpreat nations have developed in such widely diverse climates as 
v he hot plains of Mesopotamia and Yucatan and the cool hill 
country of Norway and Switzerland. Moreover, although Illi- 
nois and southern Mongolia lie in the same latitude and have 
the same mean temperature, they differ enormously in civiliza- 
tion. To put the matter in another way, we recognize two great 
sets of facts which are apparently contradictory. We are con- 
scious of being stimulated or depressed by climatic conditions, 
*nd we know that as one goes northward or southward, the dis- 
tribution of civilization is generally in harmony with what we 
should expect on the basis of our own climatic experiences. 
Nevertheless, even in our own day, regions which lie in the same 


latitude and apparently have equally stimulating climates differ 
greatly in their degree of civilization. When we compare the 
past with the present, we find the same contradiction still more 
distinctly marked. Hence our confusion. From personal experi- 
ence we know that the direct effects of climate are of tremendous 
importance. Yet many facts seem to indicate that this impor- 
tance is less than our observation would lead us to anticipate. 

The reason for this doubtful attitude can easily be discovered. 
The things that we call facts are often not well established. 
Although we believe in the influence of climate, we know little 
of the particular climatic elements which are most stimulating 
or depressing. How much do we know of the relative importance 
of barometric pressure, wind, temperature, or humidity ? What 
about the comparative effects of the climates of England and 
southeastern Russia? In addition to this, we are far from know- 
ing what type of climate prevailed in Egypt, Greece, or Mespo- 
tamia when they rose to eminence. Many good authorities have 
asserted that the climate of those regions was the same two or 
three thousand years ago as now. This view is rapidly losing 
ground, but those who believe in a change are not certain of 
its nature. They are not yet wholly agreed as to whether it has 
produced an important influence upon the particular climatic 
elements which are most stimulating to the human system. 

This book has been written because two recent lines of in- 
vestigation apparently combine to explain at least part of the 
contradictions which have hitherto proved so puzzling. In the 
first place a prolonged study of past and present climatic varia- 
tions led to the conclusion that the climate of the past was dif- 
ferent from that of the present. In early historic times, for 
example, some parts of the world appear to have been drier than 
now* and other parts moister. In any given place, however, the 
change from the past to the present has not consisted of 
~* eadily progressive tendency in one direction but of variations. 
In the places that were formerly moister than now there appear 


to have been alternate changes toward dryness and then toward 
moisture ; while in the places that are drier than in the past there 
have been corresponding variations of the opposite types. In 
a word, the climate of historic times seems to have undergone 
a pronounced series of pulsations which have varied in char- 
acter from one part of the earth to another. The second line of 
investigation which originally led to the writing of this book 
was a study of the climatic conditions under which people of 
European races are able to accomplish the most work and have 
the best health. This investigation led to the conclusion that the 
principle of climatic optima applies to man quite as fully as to 
plants and animals. According to this principle each living 
species has the best health and is most active under certain 
definite conditions of temperature, humidity, wind movement, 
storminess, variability, and sunlight, or, more exactly, under 
certain combinations of these conditions. Any departure from 
the optimum conditions leads to a decrease of activity and effi- 

During the last ten years the importance of racial inheritance 
and racial selection has been strongly emphasized. In the first 
edition of Civilization and Climate the importance of race is 
strongly emphasized, but I failed to see how important a part 
has been played by climatic changes in selecting certain types 
of people for destruction or preservation. Such selection is ap- 
parently one of the chief ways in which the character of races 
is altered. The climatic pulsations of the glacial, post-glacial, 
and historic periods appear to have exerted a profound influence 
upon the degree of habitability of different parts of the earth. 
Thus famine, distress, and disease have arisen, and the pressure 
of population has led to migration, racial mixture, and the pres- 
ervation of one type of people in one place and another some- 
where else. Natural selection under the stress of climate goes far 
toward explaining many of the cases where the distribution of 
civilization does not agree with what would be expected on the 


basis of the direct effect of climate. So important is this that 
I have written a book on The Character of Races for the ex- 
press purpose of applying the principles of natural selection to 
the history of racial development. That book might well have 
been called Civilization and Race in order to emphasize the 
fact that it is a continuation of the present work. The change 
in my own realization of the part played by climatic changes is 
one of the chief reasons why the present edition of Civilization 
and Climate is in some respects almost a new book. 

A large part of the reasoning of this book stands or falls with 
the hypothesis of climatic pulsations in historic times. The steps 
which led to the hypothesis may be briefly sketched as follows : 
In 1903, under the inspiration of the broad vision of Raphael 
Pumpelly and the careful scientific methods of William Morris 
Davis, I began to study the climate of the past. Two years' work 
with the Pumpelly Expedition sent to Turkestan by the Carnegie 
Institution of Washington led to the conviction that Reclus, 
Kropotkin, and others are correct in believing that two or three 
thousand years ago the climate of Central Asia was moister than 
now, a view which I advocated in Explorations in Turkestan. 
Later, during the Barrett Expedition to Chinese Turkestan, it 
became evident that the scientists who hold that the ancient 
climate in those regions was as dry as that of today also have 
much strong evidence to support their view. It soon appeared, 
however, that this apparent contradiction is fully explained 
by the fact that throughout the dry regions of Central Asia and 
the eastern Mediterranean the evidences of moist and dry con- 
ditions, respectively, are grouped in distinct periods ; the begin- 
ning of the Christian era was moist, for example, and the seventh 
century dry. This led to what I have called the "pulsatory 
hypothesis," which furnished a name for The Pulse of Asia. 
According to this hypothesis, although the historic and pre- 
historic past in those particular regions was in general moister 
than the present, the change from moist to dry has taken place 


irregularly in great waves. Even in early historic times certain 
centuries were apparently drier than today, while others not 
long ago were moist. In 1909, this view was confirmed during 
the Yale Expedition to Palestine, the results of which are set 
forth in Palestine and Its Transformation. 

Then a series of journeys in the drier parts of the United 
States and in Mexico and Central America, in cooperation with 
D. T. MacDougal of the Desert Botanical Laboratory of the 
Carnegie Institution, showed that the main features of previous 
conclusions apparently apply to the New World as well as the 
Old. The most important feature of this work in America was 
the measurement of the thickness of the annual rings of growth 
of some four hundred and fifty of the Big Trees of California 
the Sequoia Washingtoniana, which grows high in the Sierras. 
These measurements made it possible to form a fairly reliable 
climatic curve for 2000 years and an approximate curve for 
another thousand. The final data as to the Big Trees were pub- 
lished in The Climatic Factor, which appeared in 1915, at the 
same time as Civilization and Climate. The agreement of the 
California curve with the climatic curve of western Asia as pre- 
viously worked out, and the constantly growing evidence as to 
the reliability of tree growth as a measure of climate have done 
far more than anything else to cause the hypothesis of climatic 
mlsations to be widely accepted. Here is the way the matter 
is summed up by the British meteorologist, C. E. P. Brooks, in 
his book on The Evolution of Climate (1922) : "The question of 
climatic changes during the historic period has been the subject 
of much discussion, and several great meteorologists and geog- 
raphers have endeavoured to prove that at least since about 500 
B.C. there has been no appreciable variation. It is admitted that 
there have been shiftings of the centers of population and civi- 
lization, first from Egypt and Mesopotamia to the Mediterra- 
nean regions, and later to northern and western Europe, but 
these have been attributed chiefly to political causes and es- 


pecially to the rise of Islam and the rule of the 'accursed Turk. 1 * 
Recently, however, there has arisen a class of evidence which 
cannot be explained away on political grounds, and which ap- 
pears to have decided the battle in favour of the supporters of 
change; I refer to the evidence of the trees. The conclusions 
derived from the big trees of California have fallen admirably 
into line with archaeological work in Central America, in central 
Asia and other regions, and have shown that the larger varia- 
tions even of comparatively recent times have been very exten- 
sive, if not world-wide, in their development." 

Another important factor in perfecting the pulsatory hy- 
pothesis has been the study of the Maya ruins in Yucatan and 
Guatemala. They join with other evidence in suggesting that 
changes of climate are of different types in different parts of 
the world. Central America seems to have been relatively dry 
at times when the Big Trees of the Sierras suggest that Cali- 
fornia was moist. This is an important modification of some of 
the conclusions which I have seemed to imply in earlier books. 
At practically the same time when this newer conclusion was 
published, an almost identical idea was presented by J. W. 
Gregory of England, whose article 7s the Earth Drying Up? in 
the Geographical Journal for 1914 is the strongest criticism of 
my climatic theories that has ever appeared. It will be discussed 
more fully later. The fact that two investigators who seemed to 
be opposed should independently publish the same conclusion 
without knowing what the other was doing greatly strengthens 
the force of that conclusion. 

Having reached the conclusion that pulsatory climatic 
changes have taken place during historic times and have differed 
in type from region to region, the next step was to study the 
mechanism and cause of the supposed changes. In Palestine and 
the eastern Mediterranean the conditions of vegetation, espe- 
cially the palm and vine, as Gregory has well shown, make it 
almost certain that variations in storminess and rainfall, rather 


than in temperature, have been the primary factor. The recorded 
observations upon the mild climatic pulsations of the past hun- 
dred years support this conclusion. Various lines of evidence 
also indicate that climatic pulsations probably consist of a 
shifting of the earth's climatic zones or at least of the areas of 
cyclonic storms alternately toward and away from the equator. 
The idea as to zones, although not as to storms, was announced 
by the German geologist, Penck, at essentially the same time 
that I announced it, but the two conclusions were wholly inde- 
pendent and were based on quite different data. In both cases it 
was specifically recognized that the same kinds of climatic 
shiftings have taken place both in prehistoric and historic times, 
although the earlier changes were of greater magnitude. In these 
shiftings the temperate zone of storms appears to have been 
shoved irregularly back and forth. When it was farther south 
than at present, the subtropical countries which now are subarid 
must have been relatively moist. At the same time the subtropical 
arid belt was apparently sliif ted toward the equator so that on 
the borders of the torrid zone certain lands which now are wet 
were then relatively dry. When the shifting of zones took place 
in the opposite direction the reverse changes of climate appar- 
ently took place. 

It was only after the preceding conclusions as to climatic 
pulsations had reached essentially their present form that I 
began the next phase of the investigation, namely, the study of 
the actual effect of present climates upon human health and 
activity. This is important because some critics have supposed 
that I have unduly emphasized the importance of climatic 
changes, or have even formed a theory in regard to them for the 
purpose of bolstering up a preconceived idea that differences of 
climate from place to place are a main cause of the present dis- 
tribution of human progress. On the contrary, up to this period 
my reasoning had been somewhat as follows : If climatic changes 
have occurred during historic times, they must have had some 


economic effect because such changes alter the capacity of a 
region to support population. The economic changes in their 
turn must have led to political disturbances and migrations. 
Is there any evidence of such events at times when the climate 
suffered unusually great or rapid changes? 

The possibility of such a connection between climate and 
history has deeply interested a great number of students. Kro- 
potkin, for instance, has vividly portrayed the wav in which a 
gradual desiccation of Asia presumably drove into Europe the 
hordes of barbarians whose invasions were so important a fea- 
ture of the Dark Ages. If the change from the climate of the 
past to that of the present has been marked by pulsations rather 
than by a progressive change in only one direction and if there 
have been certain periods of rather rapid change and of great, 
though temporary, extremes, as seems highly probable, the cor- 
respondence between historic events and climatic vicissitudes 
may be closer than would otherwise seem credible. Indeed, as 
soon as I had framed a preliminary outline of the curve of 
climatic changes during historic times, it appeared as though 
many of the great nations of antiquity, had risen or fallen in 
harmony with favorable or unfavorable conditions of climate. 
During periods of drought, not only are the people of the drier 
regions forced to migrate, especially if they are nomads, but 
increasing aridity, even in more favored places such as Greece, 
must cause economic distress, and thus engender famine, misery, 
and general discontent and lawlessness. A recent journey to 
China, which gave an opportunity for a study of the famines and 
barbarian invasions that have afflicted that country for two 
thousand years, has added greatly to the already abundant evi- 
dence of the truth of this view. It has also emphasized the re- 
markably intimate connection between economic distress and 
political discontent, a connection which is obvious in advanced 
countries like the United States, Australia, and Europe as well 
as in backward regions like China, Persia, India, and Mexico. 


While these economic and political effects of climatic changes 
were being studied I became more and more impressed by the 
fact that when each country rose to a high level of civilization, 
it appears in a general way to have enjoyed a climate which 
approached more closely than now to certain well-defined con- 
ditions. These conditions appeared to resemble, but by no means 
duplicate, those now prevailing in most of the regions where 
civilization is highest. In spite of marked variations, the general 
tendency during periods of high civilization has apparently been 
toward cool, but not extremely cold, winters, and toward sum- 
mers which though warm or even hot for several months are 
generally varied by storms or at least by winds which produce 
frequent changes of temperature. It became especially evident 
that a relatively high degree of storminess and a relatively long 
duration of the season of cyclonic storms have apparently been 
characteristic of the places where civilization has risen to high 
levels both in the past and at present. Hence such places experi- 
ence much variability, a condition which later work has led me 
to believe highly beneficial. 

Up to this point in my investigations, I saw no ground for 
appealing to anything except economic and political factors in 
explanation of the apparent connection between civilization and 
climate. Then a little book on Malaria: A Neglected Factor in 
the History of Greece and Rome, by W. H. S. Jones, convinced 
me that climatic changes have altered the conditions of health 
as well as the economic situation. Later studies indicate that in 
other countries such as Central America, Indo-China, Java, and 
Egypt, as well as Greece and Rome, changes in the amount and 
virulence of such diseases as malaria and yellow fever may have 
been potent factors in diminishing the vitality of a nation. In 
fact it now seems probable that through their effect on bacteria, 
on the water supply, on the breeding places of insects, on the 
quality of the food, and perhaps in other ways climatic changes 


may exert quite as much effect as through the more direct eco- 
nomic channels. 

The study of diseases was the natural prelude to a closer 
inquiry into the fact that at times of favorable climate in coun- 
tries such as Egypt and Greece the people were apparently filled 
with a virile energy which they do not now possess. Many 
authorities attribute the loss of this to an inevitable decay which 
must overtake a nation as old age overtakes an individual. Others 
ascribe it to the lack of adaptability in various institutions, to 
increasing luxury, to contact with inferior civilizations, to a 
change in racial inheritance, or to various other factors, most 
of which are doubtless of importance. Previous to 1911 a few 
authorities such as 0. Fraas had connected the decline of energy 
in Egypt, for example, with climatic changes, but they gave so 
few reasons and the whole matter seemed so doubtful that I had 
little faith in their suggestions. At that time, Charles J. Kull- 
mer of Syracuse University sent me a manuscript calling atten- 
tion to the remarkable similarity between the distribution of 
cyclonic storms and of civilization. His article was never pub- 
lished, but was presented at a meeting of the Association of 
American Geographers. He advanced the idea that the baro- 
metric changes which are the primary cause of storms, or 
perhaps some electrical phenomena which accompany them, may 
produce a stimulus which has much to do with the advancement 
of civilization. Although he presented no definite proof, his sug- 
gestion seemed so important that I determined to carry out a 
plan which had long been in mind. This was to ascertain the 
exact effect of different types of climate by means of precise 
measurements. Dexter, in his book on Weather Influences, 
had made a beginning. Lehmann and Pedersen had made a small 
series of measurements whose highly suggestive results have been 
published under the title Das Wetter und imsere Arbeit. A 
few physicians and students of child psychology were also at 
work, and their results have been summed up in such publica- 


tions as Hellpach's GeopsycJiische Erscheinungen and Berliner's 
Einfluss von Klima, Wetter und Jahreszeit auf das N erven- und 
Seelen-leben. Nevertheless, there existed no large series of meas- 
urements of the actual efficiency of ordinary people under dif- 
ferent conditions of climate. 

The ideal way to determine the effect of climate would be to 
take a given group of people and measure their activity daily 
for a long period, first in one climate, and then in another. This, 
however, would not be practicable because of the great expense, 
and still more because the results would be open to question. If 
people were thus moved from place to place, it would be almost 
impossible to be sure that all conditions except climate remained 
uniform. If the climate differed markedly in the two places, the 
houses, food, and clothing would also have to be different. Social 
conditions would change. New interests would stimulate some 
people and depress others. Hence no such experiment now seems 

The most available method is apparently to take a group of 
people who live in a variable climate, and test them at all seasons. 
The best test is a man's daily work, the thing to which he devotes 
most of his time and energy. Accordingly, I took the records of 
four groups of people ; namely, some five hundred factory opera- 
tives in three Connecticut cities, New Haven, New Britain, and 
Bridgeport; nearly nine thousand operatives at Pittsburgh; 
three or four thousand operatives in southern cities from Vir- 
ginia to Florida; and over seventeen hundred students at the 
United States Naval Academy at Annapolis, and the Military 
Academy at West Point. In most cases each person's record 
covered an entire year, or at least the academic year. All the 
records were compared with the weather, as explained in later 
chapters. The results were surprising. Changes in the barometer 
seemed to have little effect. Humidity apparently possesses con- 
siderable importance, but the most important element is clearly 
temperature. The people here considered were phvsicallv most 


active when the average temperature ranged from 60 to 65 F., 
that is, when the noon temperature rose to 70 or more, while the 
night temperature fell to 55 or so. This is higher than many of 
us would expect. Mental activity, however, reached a maximum 
when the outside temperature averaged about 38 F., that is, 
when there were mild frosts at night. Another highly important 
climatic condition seemed to be the change of temperature from 
one day to the next. People did not work well when the tempera- 
ture remained constant. Great changes were also unfavorable. 
The ideal condition, or optimum, seemed to be mild winters with 
some frosts, mild summers with the temperature rarely above 
75 F., and a constant succession of mild storms and moderate 
changes of weather from day to day. 

The facts just stated seem to be of great significance as will 
be fully explained in this book. They suggest that the weather 
exerts a rather large and easily measurable effect upon man's 
capacity for both physical and mental work. This conclusion 
naturally led to a query as to how the climates in different parts 
of the world vary in their effect on human efficiency. Accord- 
ingly, I constructed a map showing how human energy would 
be distributed throughout the world if all the earth's inhabitants 
were influenced as were the fifteen thousand people of the four 
American groups mentioned above. This map was found to agree 
to a remarkable extent with a map of the present distribution 
of civilization based on the opinions of about fifty geographers 
and other widely informed men in a dozen countries of America, 
Europe, and Asia. Moreover, it agreed with the conclusions 
previously drawn as to the relation of climatic changes to the 
civilization of the past. Take, for example, the decadent coun- 
tries as to whose past climate we have some definite idea. In 
practically every case the climate during their more flourishing 
periods appears to have approached the optimum, as determined 
in the United States, more nearly than at present. This does 
not mean that the climate of Egypt, North India, China, 


Greece, or the Maya regions in Guatemala was ever like that of 
either New York or California. It merely means that it ap- 
proached more closely than at present to one or the other of these 
American types. Hence at the time of its greatness each region 
apparently enjoyed more than its present advantages in eco- 
nomic conditions, in freedom from parasitic diseases, and in 
direct climatic stimulus. 

When my investigations had reached this point, the first edi- 
tion of Civilization and Climate was written. During the nine or 
ten years that have since elapsed not only has much new evidence 
come to light, but my own point of view has changed consider- 
ably. The changes are set forth in the series of books and articles 
listed in the preface to the present (third) edition. They are 
referred to at some length in later chapters, but may here be 
briefly summarized. 

The comments on Civilization and Climate by historians and 
others make it more and more evident that the crux of the hy- 
pothesis of this book lies in changes of climate. The question, 
however, is not whether the climate of ancient Egypt, for ex- 
ample, was like that of modern England. It certainly was not 
and never could be. The contrast of the two countries in latitude, 
topography, and relation to land and sea makes any such close 
resemblance impossible. The real question is this : When Egypt 
rose to its greatest heights did its climate approach appreciably 
nearer than now to the type which provides the optimum condi- 
tions of energy, health, and economic strength for a people in 
the early Egyptian stage of development? Bear in mind that 
when the ancient Egyptians first rose to a state approaching 
civilization, they had not yet learned to use iron tools. Even in 
later days they had nothing like our modern skill in using wood 
and coal for heating houses, in manufacturing cotton and woolen 
cloth on such a scale that even the poor can be warmly clothed, 
in building houses that are proof against wind, rain, and cold ; 
nor had they our skill in combating disease. Hence their stage 


of development caused the optimum climate to be warmer for 
them than for us. We are able to guard ourselves against low 
temperature and exposure, and thus gain an important stimulus 
without suffering much harm. They could not withstand cold 

Bearing in mind then, that the optimum climate varies accord- 
ing to a nation's stage of civilization and also that there is 
doubtless some difference in the optimum from race to race, our 
problem becomes to determine how far the climate of the past in 
any given region was like that which is best for the stage of 
human progress, and perhaps the race, with which we happen 
to be dealing. This point of view is slightly different from that 
of the first edition of this book. The change is due largely to 
GilFillan's article on The Coldward Course of Progress in the 
Political Science Quarterly, 1920. 

So far as changes of climate are concerned, the ten years since 
this book was written have seen considerable new evidence as to 
the reality and nature of historic as well as prehistoric pulsa- 
tions. As an entire new chapter will be devoted to this matter, 
and as the comment of Brooks on the convincing character of 
the evidence has already been quoted, it is enough to point out 
here an interesting fact as to the kind of people who have ac- 
cepted the conclusions of this book. The non-scientific public, 
which has doubtless been the widest audience of Civilization and 
Climate, has accepted the book on the reasonableness of its main 
hypothesis, and with an open mind as to future proof or dis- 
proof. Geologists, archaeologists, and those geographers who 
have had a geological training are the types of scientists who 
have found the hypothesis most convincing. This is because 
most of the methods of reasoning and lines of evidence employed 
in discussions of climatic changes are such as are commonly used 
in geology, archaeology, and geography. The evidence consists 
chiefly of ancient lakes and streams, old roads in deserts, dead 
vegetation and its rings of annual growth, abandoned fields and 


irrigation systems, and especially ruins and other traces of man, 
which are really human fossils. Such evidence appeals to geolo- 
gists, archaeologists, and geologically trained geographers. 

Anthropologists, economists, and historians, on the other 
hand, have been slow to believe that climatic changes have had 
much influence upon human history. They accept, indeed, the 
geologists' conclusion that previous to recorded history great 
climatic changes drove man this way and that, destroyed ancient 
types of culture, and either wiped whole races out of existence, 
or profoundly modified them, physically, mentally, and socially. 
They apparently have no difficulty in accepting the geological 
evidence that among primitive men, as among plants and 
animals, climate has been one of the most powerful factors in 
determining the distribution and vigor of different types. But 
when it comes to the period of written history many historians, 
and some anthropologists and economists, no longer trust the 
geological methods of reasoning. Their opinions are more or 
less unconsciously molded by two widely accepted assumptions. 

The first assumption is that climatic uniformity is a normal 
condition. This idea seems wholly untenable in view of the con- 
stantly growing evidence of numerous and important glacial 
periods and other extreme types of climate at all stages in geo- 
logical history. The more we know of the geological record, the 
more clear it becomes that change, not uniformity, is the rule. 
Even in the long periods when the larger types of climatic 
changes have been absent, there is abundant evidence of minor 
fluctuations and pulsations. The second assumption is equally 
doubtful. It holds that written records and statistics are more 
reliable than the geological type of evidence. Of course written 
records and statistics are far more reliable than any other types 
of evidence if they are sufficiently full, if they can be trusted, 
and if they are prepared by people who are conscious of the 
purposes for which they are to be used. But the written and 
recorded evidence as to the climate of the past consists of mere 


scraps of information set down in most cases accidentally and 
with no idea of their possible significance in the distant future. 
Such evidence has, of course, great value, and must be studied 
assiduously. Nevertheless, it is inevitably subordinate to the 
geological type of evidence, which may be either physiographic, 
botanical, or archaeological. 

It seems clear, then, that the ultimate decision as to whether 
climatic changes have taken place on a large scale during his- 
torical times does not rest with historians. It rests primarily 
with persons who are trained in climatological, and especially 
geological, methods. During the last ten years geographers as 
a whole, in spite of some exceptions, seem to have become per- 
suaded that the historical period has witnessed a series of cli- 
matic pulsations like those of the prehistoric or post-glacial 
period although on a smaller scale. According to their own 
written statement in answer to a questionnaire, over nine tenths 
of the geographers of America, if we may judge from the fifty 
who have expressed their opinions, hold this view, although they 
are not quite so fully agreed as to how great the effect of these 
pulsations upon man may have been. Of course it is possible 
that a few geographers failed to answer the questionnaire be- 
cause they did not wish to express an opinion contrary to mine. 
I think, however, that the number of such is very limited, for 
most of those who are known to hold views unlike my own ex- 
pressed them freely. Even when all due allowance is made for 
failures to answer, it seems clear that among the people who 
are best competent to weigh the evidence the great majority 
believe in pulsations of climate. If these geographers with a 
geological training are right, there seems to be no escape from 
the conclusion that during certain periods of ancient history the 
climate of places like Egypt, Mesopotamia, and North India 
approached the optimum more closely than at present. Since the 
lower stage of culture in those early days presumably caused 
the optimum temperature for human progress to be higher than 


is now the case among the most advanced races, the climatic 
conditions were even more favorable than I realized when this 
book was first written. If this conclusion is well grounded, it 
becomes a basic fact which the historian must take into account 
just as every careful student of early man now continually takes 
account of the fact that primitive man was greatly influenced 
by the vicissitudes of the successive glacial epochs, and just as 
every economist recognizes that modern man, on a smaller scale, 
is profoundly influenced by good or bad crops. History can 
never be written correctly until its physical basis is thoroughly 
understood, and until it is recognized that economic conditions, 
and human health and energy vary from age to age almost as 
much as do the conditions of politics, religion, and personality. 
Another line where there has been much progress in the last 
ten years is the determination of the nature and importance of 
the climatic optimum for man's physical development and health 
as opposed to his economic development. After Civilization and 
Climate had been completed, I undertook a study of the rela- 
tion of deaths to climate. The results appeared in World Power 
and Evolution. Some eight and a half million deaths in about 
sixty cities in the United States and thirty in France and Italy 
were analyzed according to the average weather of each month 
during periods which in most cases amounted to at least ten 
years. Except for about 400,000 in the United States, all the 
deaths occurred during the normal period immediately preced- 
ing the Great War. In addition to this, about 50,000,000 deaths 
in other countries were analyzed less intensively, but with es- 
sentially the same results. On the other hand, about 700,000 
deaths in New York from 1877 to 1888 have been very minutely 
analyzed according to the day of death. For the six years from 
1883 to 1888 the number of deaths each day has been compared 
with the weather day by day during the two weeks ending with 
the day of death. In another investigation 7200 deaths from 
lobar pneumonia in New York in 1913 were compared with the 


weather for each day. Again, in the two largest hospitals in 
Boston the relation of the weather to 2300 deaths succeeding 
operations was looked into. At a later date the death rate during 
the influenza epidemic of 1918 in the United States was analyzed 
by still a different method in order to determine whether the 
weather had any effect in altering the rate from city to city. 

The net results of these investigations, as shown in World 
Power and Evolution and in various technical articles agree 
closely with those of the investigation of factory workers and 
students. They confirm the work of other investigators in show- 
ing almost beyond question that there is a distinct optimum 
condition of climate for man just as for plants and animals. 
This optimum varies relatively little from one set of people to 
another or from place to place. Even for negroes the departure 
from the white standard is by no means so large as would be 
expected, though it is unmistakable. Any departure from the 
optimum for a given race or individual seems to render people 
not only less efficient, but also more susceptible to disease and 
hence an easier prey to bacteria and other parasites. Moreover, 
as appears in World Power and Evolution, there is some evidence 
that departures from the optimum climate render people less 
buoyant, less capable of prolonged and steady mental activity, 
and correspondingly less likely to make progress. The signifi- 
cant fact about the whole matter is that, so far as I am aware, 
in every case where large bodies of people have been carefully 
analyzed, the same major responses to climate become evident, 
even though there may be differences in details. Thus the prog- 
ress of the last ten years seems to add appreciably to the general 
certainty as to the nature and importance of climatic optima, 
and as to the effect of departures therefrom upon health, effi- 
ciency, and progress. 

The difference between the present and first editions of this 
book in respect to natural selection and racial inheritance is 
especially important. It may be illustrated by ancient Greece. 


In the first edition I supposed that the reason for the peculiar 
ability of Greece was a mystery which there was no immediate 
prospect of solving. It was the result of some unexplained bio- 
logical process. I believed that no matter where those particular 
people might have gone or at what period they had happened 
to live they would have achieved much more than any ordinary 
people. As events actually shaped themselves, the ancient Greeks 
migrated to a land near more ancient centers of civilization 
whence they could receive the inspiration of the greatest pre- 
ceding cultures. By reason of the numerous gulfs and harbors of 
their land the Greeks were easily able to get what they wanted 
from other countries, provided they had energy enough to sail 
abroad for material riches, and capacity enough to absorb the 
mental riches with which they came in contact. So far as climate 
is concerned, Greece appears to have enjoyed unusually favor- 
able conditions throughout most of the period from perhaps 
1000 to 300 B.C., and especially about 400 B.C. Previous to 1100 
B.C., however, there seems to have been an unfavorable period 
culminating perhaps 1300 to 1200 years before Christ, while 
at a later date a period of rapid climatic degeneration from 
800 to 200 B.C. was followed by highly unfavorable conditions 
during the succeeding century. The favorable climate during the 
period of the greatest Grecian development apparently ren- 
dered the economic conditions distinctly more favorable than 
those of today, and stimulated the Greeks to a high degree of 
physical and mental energy. At the same time it rendered the 
environment unfavorable not only to the anopheles mosquito 
which causes malaria, but to other disease-bearing organisms. 
Thus the Greeks with their high inheritance enjoyed an environ- 
ment which gave full opportunity for the development of the 
best that was in them. The fall of Greece, according to the hy- 
pothesis set forth in this book ten years ago, was greatly in- 
fluenced by a rapid deterioration of climate. In the third 
centurv B.C., a decrease in rainfall caused a most serious diminu- 


tion in the capacity of Greece to support population. This in- 
creased the political difficulties while at the same time the ability 
of the people to cope with such difficulties was diminished by a 
decline in the stimulating qualities of the climate. At the same 
time the increase in marshes and in stagnant pools, because of 
changed conditions of rainfall, made the environment favorable 
for malarial mosquitoes, while poverty, a poor food supply, and 
other adverse conditions also fostered disease. In general, the 
poor economic and political situation, and the unfavorable con- 
ditions of health tended to kill off the blonde Norse invaders 
who seem to have been the leaders among the early Greeks. 

At present my view of the rise and fall of Greece differs from 
the one set forth above in only one respect, but that is highly 
important. Instead of recognizing natural selection as an im- 
portant cause merely of the decline of Greece, I now regard it 
as one of the main causes of the rise of that country. The people 
who made Greece great, as I have shown in detail in The Char- 
acter of Races, were primarily the Dorians and especially the 
lonians. These people appear to have originated far to the 
north, perhaps in the great plains of Russia. They carne to 
Greece in a series of migrations, the first of which may have been 
that of the Achseans in the fourteenth century before Christ, 
while a later invasion culminated in the Dorian invasion two or 
three centuries later. The lonians appear to have been largely 
Greeks of the old Achaean and Minoan upper classes, who were 
led to migrate by the prolonged disturbances and fighting which 
harassed Greece for generations and perhaps centuries after 
the Dorian invasion. Attica had previously been almost depopu- 
lated and did not attract the Dorians because it was infertile 
and poverty-stricken by reason of its dryness. Later, however, 
perhaps in part because of an amelioration of climate, it became 
the refuge of large numbers of the old upper classes from the 
rest of Greece. When its population became too dense, some of 
the settlers, together with many of the more able and energetic 


people from other parts of Greece, went across the 
Sea eastward to the Ionian coast of Asia Minor. Now we are 
expressly told by Thucydides and others not only that the 
settlers in Attica were a highly selected group from the leading 
families of the rest of Greece, but that they strenuously kept 
themselves apart from the lower classes. Even if an Athenian 
married a woman of the lower classes his children followed the 
social status of the mother and not of the father. Thus among 
the citizens of Athens a selected inheritance was kept almost 
unimpaired for many centuries. 

But note another important fact. Not only was there a rigid 
selection of good material when the lonians settled in Athens, 
but there appears to have been a perhaps more rigorous selec- 
tion during the earlier migrations of the people who finally be- 
came Greeks. Every migration is more or less selective because 
the weak, the feeble, the cowardly, and those lacking the spirit 
of adventure, together with those who lack determination, are 
gradually weeded out. The longer and more difficult the migra- 
tion, the more strenuous is the selection, especially among women 
and children. All but the most vigorous, both mentally and 
physically, are weeded out with peculiar rapidity. Thus the net 
result of practically every long or difficult migration in which 
women as well as men take part is to pick out a relatively small 
group of people of unusual capacity. The group may contain 
only one out of twenty, or one out of one hundred or a thousand 
of the original stock. Now the Athenians, as we have just seen, 
went through this selection twice, and may have gone through 
it at earlier times also. They also maintained the quality of the 
original stock more or less completely by refraining from inter- 
marriage with any but the elite of other regions and by various 
practices such as infanticide, which eliminated weaklings. Such 
selection with various modifications has been, I believe, one of 
the most effective factors in producing competent races. 

But what has this to do with climate? Much, because a large 


number of the migrations of history appear to have been more 
or less directly started by climatic vicissitudes. For example, 
the Irish migration to America during the nineteenth century 
was due largely to the fact that a series of good potato harvests 
in the early decades of the century permitted the population of 
Ireland to increase enormously. Then came a series of unduly 
rainy years accompanied by bad crops. Famine and distress en- 
sued, and immediately an enormous migration to America set in. 
In later years, as is shown by Bruckner's data which I have 
cited in an article on A Neglected Factor in Race Development 
(Journal of Race Development, October, 1915), the migrations 
from Ireland and likewise from Germany to the United States 
have varied in close harmony with the climatic conditions and 
consequent agricultural prosperity of both the Old World and 
the New. When the crops are bad in Europe but good in Amer- 
ica, as is not uncommon, emigration from the Old World is 
greatly stimulated for a few years. On the contrary a period of 
bad crops in America coinciding with good crops in Europe 
gradually diminishes the pressure which leads to migration. 
Similar examples on a large scale have occurred time after time 
in the history of China, Central Asia, and other regions. 

Contrary to the common belief, most parts of the world 
normally contain practically as large a population as they are 
capable of holding under the social and economic conditions 
which happen to prevail at any given time and place. The birth 
rate among mankind, as Carr-Saunders convincingly shows in 
The Population Problem, is so large and responds so quickly to 
economic changes that only a few decades or generations are re- 
quired for even a relatively depopulated country to fill up to 
what Woodruff in his Expansion of Races has called the satura- 
tion point. Thus the great majority of migrations can be under- 
stood only by thinking of all parts of the world as normally 
having nearly their full quota of population. Among primitive 
hunting tribes, for example, this quota may mean only one 


person per square mile, while in a modern highly civilized com- 
munity it may mean a thousand per square mile. The conditions 
are like those of a bucket filled to the brim with water. As soon 
as any object is dropped into the bucket some water runs over. 
In the same way, in most parts of the world any deterioration of 
economic conditions such as frequently arises from bad crops, 
immediately necessitates either a lowering of the standard of 
living or a diminution of population through an increased death 
rate by reason of poverty, famine, or war, or through migration. 
A migration, as a rule, is merely a slow drifting of people with 
unusual energy and initiativefrom unfavorable to favorable 
districts. But not infrequently, and especially after one of the 
sudden climatic vicissitudes which have been common in history, 
it becomes a violent stream of invasion such as many of the bar- 
barian outpourings about 1400 to 1200 years before Christ 
and again at various later periods. 

The original Greeks apparently took part in extensive wan- 
derings of both the mild and violent kind, and natural selection 
presumably worked among them effectively. The net result was 
a highly selected race which gave the world a marvelous group 
of famous men. These men, it appears, accomplished great things, 
not only because of their high innate qualities, but because grow- 
ingly favorable climatic conditions from six to four hundred 
years before Christ improved their economic situation and 
helped to give them great energy and splendid health. According 
to this view, Greece apparently lost her ability partly because 
the fine original stock became mingled with weaker elements, 
and partly because the change of climate which began soon after 
400 B.C. and which took place most rapidly from 300 to 200 
B.C., not only enabled malaria to spread with baleful rapidity, 
but introduced a stage of diminishing resources, scanty food 
supply, overpopulation, and lessened climatic stimulus. These 
factors presumably combined with other well-known conditions 
to produce poor health and perhaps restriction of families among 


the upper classes, thus killing off the old dominant stock of 
northern origin. Hence the racial elements to which Greece owed 
her greatness disappeared, and the country fell into intellectual 
insignificance. Other factors undoubtedly cooperated, but such 
conditions as political corruption, social degeneracy, and undue 
personal ambition are probably results of racial decay and poor 
health quite as much as causes. The essential point is that at 
the beginning a time of climatic stress among nomads in rela- 
tively cool grasslands seems to have led to migration and a 
favorable type of selection. Another period of similar stress 
amid a highly developed people in a relatively southern land 
where there was less opportunity or incentive for migration led 
to the dying off of the more able people. Yet even in this case 
many of the most competent Greeks migrated, thus still farther 
impoverishing the mother country and giving rise to highly 
gifted colonies like the Alexandrian community in Egypt. 

To sum up the whole hypothesis of the relation of climate to 
civilization, here are the factors as I see them at present. Most 
parts of the world are so well populated that any adverse eco- 
nomic change tends to cause distress, disease, and a high death 
rate ; migration ensues among the more energetic and adventur- 
ous people. Perhaps the commonest cause of economic distress is 
variations in weather or climate which lead to bad crops or to 
dearth of grass and water for animals. Such economic distress 
almost inevitably leads to political disturbances and this again 
is a potent cause of migrations. The people who migrate perforce 
expose themselves to hardships and their numbers diminish until 
only a selected group of unusually high quality remains. Such 
people, either as warlike invaders or in small bands, enter a new 
country. They may find it well populated and merely impose 
themselves as a new ruling class, as seems to have happened 
several times in India, or they may find it depleted of people as 
in Attica. When the period of climatic stress is ended and the 
climate improves, the dominant newcomers not only possess an 


unusually strong inheritance, but are stimulated by unusually 
good economic conditions and by improved conditions of health 
and energy. Moreover since the population is apt to remain 
below the saturation point so long as the climate improves, the 
standards of living tend to rise and to become relatively high. 
Thus many people are freed from the mere necessity of making 
a living and have the opportunity to devote themselves to the 
development of new ideas in literature, art, science, politics, and 
other lines of progress. The repeated coincidence between periods 
of improving climate and periods of cultural progress appears 
to be due not only to the direct stimulus of climate, as I sup- 
posed in the first edition of this book, but to that stimulus com- 
bined with a high racial inheritance due to natural selection. 
This, I am well aware, by no means offers a complete explanation 
of history, for many other elements must also be considered. But 
it helps to explain many historic events which have hitherto been 
only partially understood. 

Here, once more, is the sequence climatic changes produce 
economic results through an increase or a diminution of the food 
supply. Thus there arises either a temporary condition of under- 
population with comparative political tranquillity and oppor- 
tunities for the growth and expansion of civilization, or a con- 
dition of overpopulation with consequent political turmoil, 
war, migration, and the repression of civilization. This point 
of view was dominant when I wrote The Pulse of Asia and 
Palestine and Its Transformation. Climatic changes also appear 
to have a direct effect in stimulating or repressing man's physi- 
cal activity, a viewpoint which dominated the first edition of 
the present book. It is obvious that through their effect upon 
food, insects, bacteria, and man's own powers of resistance 
climatic changes must exert a great influence upon disease. 
Hence I was led to write World Power and Evolution from the 
standpoint of disease and the death rate. But this does not end 
the matter, for climate apparently exerts a direct selective 


effect in preserving certain types of people and destroying 
others, and it certainly exerts these effects indirectly through 
various conditions already mentioned. Therefore it was only 
logical that The Character of Races should center around 
natural selection, especially in its climatic aspects. The next 
step is obviously a study of the relation of climate to mutations 
and thus to the origin of the new types among which natural 
selection makes its choice, but that is as yet impossible. Beyond 
this lies the synthesis of the effects which climate produces 
through economic and political conditions, through war and 
migration, food and natural resources, energy and health, and 
through natural selection and mutations. And all these results of 
the climatic environment must be put into due relation not only 
with the results of the other factors of physical environment, 
but with the opposite side of the shield, that is, with the purely 
human factors such as institutions, customs, ideas, and all man's 
passions, ideals, and aspirations. Then it will be possible to form 
a true philosophy of history. Meanwhile the present edition of 
Civilization and Climate tries to take a broader and deeper view 
of human progress than its predecessor, but it makes no claim 
to deal exhaustively with more than one small phase of the 
matter, namely, the direct effects of climate upon human ^health 
and energy. 


THE problem which confronts us is primarily to separate the 
direct effects of climate from those of inheritance, regard- 
less of whether the inheritance has been influenced by the climate 
of the past. It may be made concrete by comparing two sharply 
contrasted races, Teutons and negroes. Suppose that there were 
two uninhabited Egypts, exactly alike, and that one could be 
filled with negroes and the other with Teutons. Suppose that 
these settlers were average members of their races, and were 
equipped with the same religion, education, government, social 
institutions, and inventions. This might easily happen if the 
negroes came from the United States. Suppose, further, that 
neither race received new settlers from without, or lost any 
except through natural selection. Which would succeed best? 
"The Teutons, of course," is the answer. "What a foolish ques- 
tion." But is it so foolish? You are thinking of the first genera- 
tions. I am thinking of the twentieth or later. Does anyone know 
what five hundred or a thousand years of life in Egypt would 
do for either Teutons or negroes if no new blood were intro- 
duced ? 

At the end of that time the two sets of people would assuredly 
be different, for the effect of a diverse inheritance would last 
indefinitely. The advantage in this respect would presumably be 
on the side of the Teutons. I wish to emphasize this matter, for I 
shall have much to say about the effect of climate, and I want 
to make it perfectly clear that I do not underrate the impor- 
tance of race. Although the matter is by no means settled, many 


authorities think that the brain of the white man is more com- 
plex than that of his black brother. Strong, in the Pedagogical 
Seminary for 1913, and Morse, in the Popular Science Monthly 
for 1914, have shown that in Columbia, South Carolina, the 
white children are mentally more advanced than the colored. By 
applying the Binet tests to 225 children in two white schools and 
to 125 children in a colored school, they obtained the following 
table, showing the amount by which the two races exceeded or 
fell short of what would be expected. 


More than one year backward, 29.4% 10.2% 

Satisfactory, 69.8% 84.4% 

More than one year advanced, 0.8% 5.3% 

Among the white children those from the middle classes made 
a better showing than those of factory operatives, but both 
were ahead of the colored. So far as home environment is con- 
cerned, the factory children have almost no advantage over the 
colored children. A slight advantage may possibly arise from 
the fact that when the Binet tests were originally devised, they 
were designed to measure the capacities of white children. The 
negro race may have capacities which the white does not possess 
and which do not play a part in the tests. In appreciation of 
humor, for example, and in equability of temperament there 
can be little question that the black rnan surpasses the white. 
These things, however, can scarcely account for the fact that 
29.4 per cent of the colored children showed a mental develop- 
ment more than a year behind that which would be expected from 
their age, while only 10.2 per cent of the white children were 
equally backward. 

So far as I am aware, every exact test which has been made 
on a large scale indicates mental superiority on the part of the 
white race, even when the two races have equal opportunities. 
For example, in Washington the colored children remain in 


school quite as long as the white, but they do not accomplish so 
much in the way of study and do not reach so high a grade. In 
the cities of the South, Mayo and Loram find that where the 
races are given essentially the same instruction, the proportion 
of whites who are promoted is greater than that of negroes. 
Moreover, the difference seems to increase with years, which 
suggests that the average colored child not only stands below 
the average white child in mental development at all ages, but 
ceases to develop at an earlier age. In the high schools of New 
York, the superiority of the white race is shown by Mayo's 
examination of the average marks. By the time the children 
reach the high school, the processes of promotion have weeded 
out a much larger proportion of colored children than of white. 
Hence, the negroes form a specially selected group whose supe- 
riority to the average of their race is more marked than the 
superiority of the white high school children when compared 
with the rest of the white race. Nevertheless, the average marks 
of the white children are distinctly higher than those of the 

In order to test the capacity of the two races in a wholly 
different way, I have made a comparison of white and colored 
workmen employed under precisely similar conditions. The first 
case was a cigar factory at Jacksonville, Florida. The employees 
were practically all Cubans. Both the whites and the blacks have 
very little education, and their home environment in Cuba differs 
to only the smallest extent. They earn good wages, but are often 
out of work, and are generally shiftless and unreliable. There is, 
of course, no color line in Cuba, and the same is true in the cigar 
factories. Black men and white work side by side at the same 
tables. In such a factory, if the black man is as capable as the 
white he has exactly as good a chance, for he is paid by the piece, 
and his earnings depend entirely on himself. What, then, do we 
find? Taking all the operatives, we have 39 white and 65 negroes. 
Their average earnings, as measured by the wages of two weeks, 


are in the ratio of 100 for the whites to only 51 for the negroes. 
To make the comparison more favorable to the negroes, let us 
eliminate those who roll low-grade cigars where little skill is 
required and the pay is low. We then have 39 white men and 44 
negroes. They are doing exactly the same work under exactly 
the same conditions, but the whites earn a dollar where the 
negroes earn 75 cents. At a similar factory at Tampa, Florida, 
17 colored men were at work and 303 white. In this case prac- 
tically all of the few negroes happened to be men of long experi- 
ence, while many of the whites were comparatively new. Never- 
theless, the whites are still on a par with the colored men, the 
ratio being 100 to 99.8. 

One of the best places for comparing the two races is the 
Bahama Islands. For reasons which I shall present later, the 
process of making "poor whites" has probably gone farther in 
the Bahamas than in almost any other Anglo-Saxon community. 
Part of the white people are like their race in other regions, but 
a large portion have unmistakably degenerated. Witness their 
intense and bigoted speech, their sunken cheeks and eyes, their 
sallow complexion, and their inert way of working. In spite of 
racial prejudice, there is no real color line in the Bahamas. 
Persons with more or less negro blood are worthy occupants of 
the highest positions, and are universally accepted in the most 
exclusive social circles. The British government gives the negro 
every possible opportunity. The state of affairs may be judged 
from the remarks of a "poor white" sailor, who said to me : "You 
want to know why I likes the southern states better than the 
North. It's because they hates a nigger and I hates him, too. 
What kind of a place is this where they do everything for the 
nigger and nothing for the white man? It's bad enough to have 
to go to jail, but it's damned hard for a white man to be taken 
there by a nigger constable." In one Bahaman village I saw 
negro girls teaching white children in the public schools. In that 
same village a number of the leading white men cannot read or 


write. When they were children their parents would not send 
them to school with negroes. The despised negroes learned to 
read and write, but have now largely forgotten those accomplish- 
ments. The proud whites grew up in abject ignorance. Today 
the same thing is going on. I visited two villages where the white 
children are staying away from school because they will not go 
to negro teachers. The homes of such whites are scarcely better 
than those of their colored neighbors, and their fathers are 
called "Jim" and "Jack" by the black men with whom they work. 
Racial prejudice apparently works more harm to the whites 
than the blacks. So far as occupations go there is no difference, 
for all alike till the soil, sail boats, and gather sponges. 

When the lumber industry was introduced into the islands, 
whites and blacks were equally ignorant of the various kinds of 
work involved in cutting trees and converting them into lumber. 
The managers did not care who did the work so long as it was 
done. They wanted three things : strength, docility or faithful- 
ness, and brains. They soon found that in the first two the 
negroes were superior. Time and again persons in authority, 
chiefly Americans, but also some of the more capable native 
whites, told me that if they wanted a crew of men to load a boat 
or some such thing, they would prefer negroes every time. The 
poor white shirks more than the colored man, he is not so strong, 
and he is proud and touchy. Other things being equal, the negro 
receives the preference. But other things are not equal. The very 
men who praise the negroes generally added : "But you can't use 
a negro for everything. They can't seem to learn some things, 
and they don't know how to boss a job." The payroll reflects 
this. Even though the negroes receive the preference, the 4*00 
who are employed earn on an average only about 60 per cent as 
much as the 57 white men. If we take only the 57 most competent 
negroes, their average daily wages are still only 88 per cent as 
great as those of the native whites. The difference is purely a 
matter of brains. Although the white man may be ignorant and 


inefficient, with no more training than the negro, and although 
his father and grandfather were scarcely better, he possesses an 
inheritance of mental quickness and initiative which comes into 
evidence at the first opportunity. 

All these considerations seem to point to an ineradicable racial 
difference in mentality. As the plum differs from the apple not 
only in outward form and color, but in inward flavor, so the 
negro seems to differ from the white man not only in feature and 
complexion, but in the workings of the mind. No amount of 
training can eradicate the difference. Cultivation may give us 
superb plums, but they will never take the place of apples. We 
have tried to convert the black man into an inferior white man, 
but it cannot be done. Initiative, inventiveness, versatility, and 
the power of leadership are the qualities which give flavor to the 
Teutonic race. Good humor, patience, loyalty, and the power 
of self-sacrifice give flavor to the negro. With proper training he 
can accomplish wonders. No one can go to a place like Hampton 
Institute without feeling that there is almost no limit to what 
may be achieved by cultivation. In an orderly, quiet way, those 
negro boys and girls go about their daily tasks and give one the 
feeling that they are making a real contribution to the world's 
welfare. To be sure, they work slowly, they are not brilliant in 
their classes, they rarely have new ideas in their manual work, 
but yet they are faithful. The willing, happy spirit of their work 
is something that we nervous, worried white people need sorely 
to learn. Once in a long time there comes a leader, a man to 
whom both white and black look up, but such leadership is 
scarcely the genius of the race. Yet leadership is what the black 
man must have. At such places as Hampton he gets it, and one 
realizes that the white man's initiative joined to the Christian 
spirit which is there so dominant can give a training which 
overcomes much of the handicap of race. 

Having turned aside to pay tribute to the potency of race, 
education, and religion in determining the status of civilization, 


let us come back to physical environment. What part does this 
play? Is it so important that a strong race in an unfavorable 
climate is likely to make no better showing than a weak race 
in a favorable climate? How far can a bad climate undo the effect 
of a good training? 

In answer to these questions, we may well compare the Teu- 
tonic and negro races when each is removed from the climate in 
which it originally developed. Before proceeding to this a word 
should be added to forestall any possible misunderstanding of 
rny attitude toward the southern parts of the United States 
and toward other progressive regions which, nevertheless, suffer 
somewhat from climatic handicaps. In searching for the truth 
I shall be forced to say some things which may not be wholly 
pleasing to residents of such regions. It must be clearly under- 
stood, however, that these are not stated on my own authority. 
All are based either on the consensus of opinion among a large 
number of persons including many southerners, or upon the 
exact figures of the United States census or other equally re- 
liable sources. My part has been simply to interpret them. Be- 
lieving that the South contains a great number of people who in 
all essential respects have an inheritance equal to that of the 
best northern stocks, I have tried to find out why the southern 
part of the United States has prospered less than the northern. 
This does not mean that I reject the old ideas as to the cause, 
but simply that I emphasize another which has not received 
sufficient consideration. It does not discredit the South nor its 
people. It does not alter the fact that southerners possess a 
courtesy and thoughtfulness which we of the worried and hurried 
North need greatly to imitate. Nor does it mean that men of 
genius are not as likely to be born in one section as another. 
Instead of this, it merely indicates that in addition to the many 
efforts now being made to foster progress in the South by other 
means, we should add a most vigorous attempt to discover ways 
of overcoming the handicap of climate. This book is written with 


the profound hope that the truth which it endeavors to discover 
may especially help those parts of the world whose climate, al- 
though favorable, does not afford the high degree of stimulation 
which in certain other restricted areas is so helpful. 

Let us first undertake a study of what the census shows as to 
negroes and whites in different parts of the United States. The 
only people whom we can compare with accuracy are the farmers, 
for they are the only ones for whom exact statistics are avail- 
able. Fortunately they are the part of the community where 
social prejudices and other hampering conditions have the 
smallest influence. The prosperity of the farmer, more than that 
of almost any other class of society, depends upon his own indi- 
vidual effort. If he is industrious, he need never fear that he and 
his family will not have a roof over their heads and something 
to eat. Even when the crops are bad, he rarely is in danger of 
suffering as factory operatives often suffer, at least not in the 
eastern United States, with which alone we are now concerned. 
Moreover, the prejudice against colored people has little effect 
upon farmers. No one hesitates to buy vegetables peddled by a 
darkey farmer. Finally, farming is the occupation in which the 
South has been least hampered as compared with the North. For 
over half a century the negro has been able to buy land freely in 
any part of the country. The southerners, whether white or 
black, have suffered economically because of slavery and the con- 
sequent war, but they have a good soil and a climate far better 
for agriculture than that of the North, and they have peculiarly 
good opportunities to raise tobacco and cotton, two of the great- 
est money-making crops in the world. Taken all in all, the 
farmers of the country ought to show the relative capacities of 
different races and of the same race under different conditions 
better than almost any other class of people. 

In 1904 the United States Census Bureau published a bulle- 
tin on the negro. From that I have prepared Table 1 showing 
the relative conditions in four groups of states in 1900. The first 




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Average a 
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land whic 


row of numbers (line 1) shows the total number of white and 
colored farmers. The second row shows that the farms of the 
northern white men average about 100 acres in size, while those 
of the southern white men are larger. The colored farms, on the 
other hand, have an average size of about 50 acres. In the next 
row of figures, line 3, we notice that the northerners forge ahead. 
Even in the relatively hilly states of New York and Pennsyl- 
vania, the white farmers have improved 63.5 acres per farm, or 
69 per cent of the whole, leaving only 31 per cent in the rough 
state of bushes or woods. The northern negroes do exactly as 
well in proportion to their holdings, for they have cleared 33.0 
acres, which is also 69 per cent of the average farm. In the 
Carolinas, Georgia, and Florida, on the contrary, the white men 
have improved only 34 per cent of their land, and the colored 
men 58 per cent. For the states farther west (comparison B), 
approximately similar conditions prevail. The negroes are 
obliged to clear a larger percentage than the whites because 
their small holdings would not otherwise furnish a living. The 
significance of the figures lies in the fact that the northerners, 
whether white or black, show more energy in improving their 
land than do the southerners of the same kind. 

Since this table was in print the corresponding data for 1910 
and 1920 have appeared. Unfortunately they are less full than 
for 1900 and do not include the value of products, line 9. For 
line 4 the percentages for each of the three census years are as 
follows : 


Comparison A 

Comparison B 




































In comparison A, the gain of the other groups in relation to 
the northern white farmers is noticeable. This, however, does 


not mean merely that agriculture is improving in the South, but 
also that it is declining in the Middle Atlantic States. In B, the 
percentages are almost unchanged. 

In both comparisons of Table 1 items 4 and 9 are the most 
significant. They show the value of the farms and the value of 
the annual products. In each item of Table 1 the values are stated 
in dollars as given in the census report, while underneath I have 
added percentages. In computing the percentages the highest 
value is reckoned as 100 per cent and the rest figured accord- 
ingly. In each item of both comparisons for all three census 
years, as given in Table 2, the northern whites stand at the top. 
In general, taking both comparisons into account, the northern 
white man's farm is worth twice as much as that of his colored 
neighbor, and he gets twice as much from it. The southern white 
man has a farm worth less than that of the northern negro, but 
he gets from it approximately the same amount of products. The 
southern negro's farm is worth less than half as much as the 
southern white man's and he gets from it about two thirds as 
much. Taking all the farms from our four groups of states 
and reckoning them according to the value of what they actually 
produced in 1900 and of their value in 1920, the census ranks 
them as shown in Table 3. 


Per value of Per value of 

products in 1900 farms in 1920 

Northern whites, 100 100 

Southern whites, 51 44 

Northern negroes, 49 49 

Southern negroes, 34 18 

This little table possesses profound significance. It shows un- 
mistakably two types of contrast. First, there is the racial con- 


trast, the result of long inheritance. That, apparently, is what 
makes the negroes fall below the whites in both the North and 
the South. There is also a climatic contrast. That, apparently, 
is why the negroes who come to the North rise above the usual 
level of their race, while the whites of the South fall below the 
level of theirs. I realize that the contrast between the two sec- 
tions is explained in a hundred ways by as many different people. 
One ascribes it to the fact that slavery was a poor system eco- 
nomically. Another says that the South is cursed for having 
consented to the sin of slavery. Again, we are told that the pre- 
dicament of the South is due to the War of Secession, the failure 
to develop manufactures, the absence of roads and railroads, 
bad methods of farming, the presence of the negro making the 
white man despise labor, and many other equally important 
causes which cannot here be named. Still other authorities 
ascribe the condition of the South to its supposed settlement by 
adventurers, whereas the North had its Pilgrims. 

I would not minimize the importance of these factors. All are 
of real significance, and if any had been different, the South 
would not be quite what it is. All depend upon the two funda- 
mental conditions of race or inheritance, and place or climate. 
Yet in the contrast between the North and South, the climatic 
effects seem to be the more potent. Slavery failed to flourish in 
the North not because of any moral objection to it, for the most 
godly Puritans held slaves, but because the climate made it un- 
profitable. In a climate where the white man was tremendously 
energetic and where a living could be procured only by hard and 
unremitting work, it did not pay to keep slaves, for the labor of 
such incompetent people scarcely sufficed to provide even them- 
selves with a living, and left little profit for their masters. In the 
South slavery was profitable because even the work of an ineffi- 
cient negro more than sufficed to produce enough to support him. 
Moreover, the white man was not energetic, and his manual work 
was not of much more value than that of a negro. Hence, it was 


easy to fall into the habit of using his superior brain, and letting 
the black man perform the physical labor. If the Puritans had 
settled in Georgia, it is probable that they would have become 
proud slave-holders, despising manual work. 

So far as inheritance is concerned, the white southerners, 
according to the generally accepted principles of biology, must 
be essentially as well off as the white men of the North. New 
England has probably had a certain advantage from the strong 
fiber of her early settlers, but that section is excluded from our 
comparison because it has so few colored farmers. In New York, 
Pennsylvania, New Jersey, and the states farther west, the white 
farmers in 1900 were of highly mixed origin, and there is little 
reason to think that they inherit any greater capacity than do 
the white men of the South. Hence, we infer that the difference 
shown by the census is largely a matter of climate. It has arisen 
partly by indirect means such as slavery and disease, partly by 
direct means such as the disinclination to physical exertion. This 
demands emphasis, for we are told that the South needs nothing 
but a fair opportunity, plenty of capital, and abundant roads, 
railroads, and factories, or else it needs only education, a new 
respect of one race for the other, cooperation between the two 
for the sake of the common good, and a deeper application of 
the principles of Christ. All these things are sadly needed, but 
it is doubtful whether they can work their full effect unless sup- 
plemented by a new knowledge of how to neutralize the climatic 
influences which seem to underlie so many southern problems. In 
the climate of the South a part of the white population becomes 
a prey to malaria, the hookworm, and other debilitating ail- 
ments. People cease to be careful about food and sanitation. 
Even those who are in good health do not feel the eager zest for 
work which is so notable in the parts of the world where the 
climatic stimulus is at a maximum. Thus one thing joins with 
another to cause a part of the people to fall far below the level 
of their race, and to become "Poor Whites," or "Crackers." 


These increase in number as one passes from a more to a less 
favorable climate. It is their run-down, unkempt farms which 
bring the average of the southern whites so dangerously near the 
level of the negroes. The best farms of the South vie with those 
of the North. They show what could be done if all the inhabitants 
could be instilled with the energy and wisdom of the best. 

Aside from North America the only large area where Teutons 
and negroes come into direct contact as permanent inhabitants 
is South Africa. There they meet on practically equal terms. The 
English and Boers began to settle in South Africa in large num- 
bers only in the first half of the nineteenth century. In 1921 the 
South African Republic contained about 1,500,000 Europeans, 
4,700,000 Bantu natives, and 700,000 other natives and 
Asiatics. A large proportion of the white men were not born 
there, and hence the new conditions have not had time to pro- 
duce their full effect. The majority of the natives are Zulus, but 
the most capable appear to be the Basutos, an allied race who 
have preserved a large measure of independence in the Draken- 
berg mountains. Both the Zulus and the Basutos came from 
the North a few generations ago. Some preceded the white man 
and some have come since his arrival. 

The colored people are most numerous in the north and east 
of the Republic, that is, in Rhodesia and Natal. The white men 
are most abundant in the south and in the central plateau, that 
is, in Cape Colony, Orange River Colony, and Transvaal. With 
ever increasing force, however, the blacks are pushing into the 
white man's country. They are brought as laborers for the 
mines ; they are wanted for the farms ; they are in demand as 
servants ; and they are themselves taking up farms and success- 
fully cultivating them. They are doing more than this, however, 
for they are actually ousting the Europeans. In 1902 the Eng- 
lish and the Boers finished a bitter war. Ten years later their 
enmity had almost vanished in the common fear of the negro. 
Aside from the disturbances due to the European War of 1914, 


the great political question has long been the black man. One 
party advocates segregation, with a white man's South Africa 
in the highlands from Transvaal southward, and a black man's 
South Africa in Natal and Rhodesia. No black man, they say, 
should be allowed to live permanently outside his own country, 
although he might go elsewhere to work temporarily. The other 
party holds that such measures are too radical, but it also 
recognizes the gravity of the situation. 

The problem presents itself under an economic guise. The 
colored men have a lower standard of living than the whites. 
Hence they work more cheaply. They furnish so abundant a 
supply of labor that white laborers have no chance. Thus a 
large number of the Europeans even a tenth according to 
ardent believers in the future of South Africa are "poor 
whites." They are a shiftless set, living from hand to mouth, 
proud of their race, yet less efficient than the blacks. The prob- 
lem of preventing them from becoming an immediate charge 
upon the community is serious. They lack the push and energy 
which characterize the rest of the white population. According 
to Stevens, in his book White and Black, 5 per cent of the 
white population in certain regions have fallen so low that they 
would rather resort to crime than work in competition with the 
black man. These figures have been questioned, but they are 
abundantly confirmed by Dr. Andrew Balfour, Director-in- 
Chief of the Wellcome Bureau of Scientific Research in London. 
In some lectures on Sojourners in the Tropics and Problems of 
Acclimatisation, published in The Lancet in 1923, he states that 
he "referred the matter to Colonel P. G. Stock, of the Ministry 
of Health, who knows South Africa intimately, and he confirmed 
Huntington's statement, pointing out, however, that in parts of 
the Transvaal chronic malaria may be to blame." The most 
sinister fact is that these "poor whites" appear to have been 
largely born in the country. The newcomers are on the whole 
more energetic. They find employment, and if they have difficulty 


in one place, move on to another. The poor whites lack the ini- 
tiative to do this. If they fall into difficulties, they tend to lie 
down and give up. They need higher wages than the blacks in 
order to maintain their traditional standard of living. They are 
not efficient enough to get higher wages. If they had the restless 
energy which characterizes the children and grandchildren of 
emigrants from Europe in Canada, for example, they would 
scarcely fall into such straits. 

Since the problem is economic, the South Africans are striv- 
ing to apply economic remedies. This is wise, but success is 
doubtful unless other factors are also considered. Back of the 
economic facts, and in many ways conditioning them, lies the 
climate. South Africa is supposed to have a climate admirably 
adapted to Europeans. I shared the common opinion until I 
began to gather statistics of the eff ect of climate upon efficiency. 
These, as will be shown later, indicate that although the South 
African climate is pleasant, it lacks the stimulating qualities 
which are so important in Europe and North America. This 
lack of stimulus increases rapidly as one goes from south to 
north. Here, then, is the situation that confronts us : In South 
Africa the white men settled first in the regions most favorable 
from a climatic point of view and then pushed northward into 
worse conditions. Even the best parts of South Africa cannot 
approach England and Holland in the excellence of their cli- 
mate. Hence, the white settlers are everywhere at a disadvantage. 
On the other hand, the Bantu negroes have come into South 
Africa from the north, where the climate is far less favorable 
than in their new homes. Thus the two races face each other 
under conditions which lessen the white man's energy, while they 
stimulate the black man. The whites are still far ahead, and will 
doubtless continue to be so indefinitely. Nevertheless, the weaker 
ones are being weeded out and prepared for destruction. What 
the final result will be, no man can say. It depends upon whether 
we can discover a means of preventing the deterioration which 


now seems to attack a portion of the population when people 
move from a good climate to a worse. 

A more striking case than that of South Africa is found in 
the Bahama Islands. At the time of the American Revolution a 
considerable number of Loyalists were so faithful to England 
that they sacrificed their all in order to escape from the new 
flag with its stars and stripes. Leaving their homes in Georgia 
and other southern states they sought the British territory of 
the Bahamas. Other colonists came from Great Britain. Now, 
after from three to five generations, the new environment has 
had more opportunity than in South Africa to produce its full 
effect. Almost nowhere else in all the world have people of the 
English race lived as genuine colonists for several generations 
in so tropical a climate. What has been the result? There can 
be but one answer. It has been disastrous. Compare the Bahamas 
with Canada. The same sort of people went to both places. 
Today the descendants of the Loyalists in Canada are one of 
the strongest elements in causing that country to be conspicu- 
ously well governed and law-abiding, and the descendants of 
other colonists, both British and French, vie with them in this 
matter. In the Bahamas the descendants of the same type of 
people show today a larger proportion of poor whites than can 
probably be found in any other Anglo-Saxon community. Al- 
though no figures are available, my own observations lead to 
the conclusion that the average white farmer is scarcely ahead 
of the average negro. 

Whatever the exact figures may be, there can be no question 
that in the Bahamas the two races tend to approach the same 
level. This seems to indicate a marked retrogression of the white 
race in regions which are climatically unsuitable. Let me hasten 
to say that many of the more intelligent Bahamans do not differ 
from the corresponding portions of the Anglo-Saxon race else- 
where. At home they feel themselves handicapped, but when the 
young people go away to the northern United States or Eng- 


land, they frequently show marked ability. Their inheritance is 
still good. As to the poor whites, who were described in connec- 
tion with the lumber industry, it is not so certain that their in- 
heritance remains unimpaired, for in some villages genuine ab- 
normalities both of body and mind are seen. This, however, may 
be due to the intermarriage of cousins which has been common 
in certain communities. 

The inefficiency of many of the white Bahamans, however, is 
not due to intermarriage, as is sometimes implied, for villages 
where this prevails are scarcely worse than those where it is no 
more common than in America. Nor is the inefficiency due to 
disease. The hookworm is practically unknown. According to 
a report of Dr. McHattie, Chief Medical Officer of the Islands, 
only two cases had been reported up to October, 1913. In this 
report, for which I am indebted to the courtesy of Dr. J. A. 
Ferrell of the Rockefeller International Health Commission, the 
author points out that "the remarkably rapid manner in which 
the soil . . . dries after even the heaviest rain" prevents the 
development of the infective larvae. For similar reasons malaria 
is no more prevalent than in Delaware, for instance, and in gen- 
eral the islands are decidedly healthful. A monotonous diet may 
be another detrimental factor, but it is scarcely the root of the 
matter. Many of the people are well fed, and all could be so if 
they displayed any energy. Indeed, many people say that life 
is altogether too easy in the Bahamas. The soil is wonderfully 
fertile, crops of some kind will ripen at all seasons, and a man 
can work less than half his time and still readily procure an 
abundance to eat and wear for himself and his family. On the 
other hand, we are often told that the difficulties of life have 
broken the spirit of the inhabitants. The soil, in spite of its rich- 
ness, is thin, and rocks are so abundant that the plough is almost 
unknown. Hand agriculture in little patches in the midst of 
naked limestone is the rule. It cannot be denied that there are 
difficulties in comparison with many other tropical countries. 


For instance, I was talking with a negro whose parents were in 
a slave ship bound from Africa to Cuba when a British warship 
captured it. The slaves were taken to the Bahamas and liberated. 
In answer to a question as to how his parents liked the islands 
compared with Africa, the son said: "They didn't like it. They 
used to say, 'In Africa one could lie around all day and do 
nothing and always find something to eat. Here one has to work 
or else starve.* " The truth seems to be that compared with 
North Prussia or Maine the Bahamas are a very easy place in 
which to make a living, but that much more work is needed than 
in some other tropical regions. They are at the happy mean. 
Other difficulties such as the tropical hurricanes which sweep 
over the country once in every few years ; insect pests, which 
are neither more nor less harmful than in other countries ; the 
American tariff; competition with Cuba, and above all the iso- 
lated position of the islands are frequently cited as causes of 
the constant Bahaman failures. The islands are always suffering 
from bad luck, and something must be to blame. 

All these various factors doubtless play a part in retarding 
the development of the Bahamas. Back of them, however, lies 
a factor of even greater import, namely, an inertia due to the 
climate. It does not cause the difficulties mentioned above, but 
it aggravates them and makes it almost impossible to overcome 
them. I talked about this with perhaps fifty of the more intelli- 
gent people, including both natives and foreigners who have 
been there a number of years. Almost without exception they 
said the same thing. "This climate is one of the best in the world. 
You can see that for yourself. It is very healthful, and we have 
very few sicknesses. The only trouble is that it does not make 
one feel like work. In winter it is all right, although even then we 
cannot fly around the way you Americans do. We always feel 
lazy, and in summer we want to sit around all the time." As an 
American picturesquely put it : "Until I came to the Bahamas 
I never appreciated posts. Now I want to lean against every one 


that I see." Many of the men and almost all the women com- 
plained of feeling tired. Even the children are listless. One young 
man stated the case very strongly, "We go to bed tired in sum- 
mer and we get up more tired, and the summer lasts from April 
to October." Again and again people said : "Oh, it's all very well 
for you to think we're lazy, but try living here six months or a 
year and you'll be as lazy as we are. It's something in the air. 
Just look at these young ministers who come out from England. 
At first they are full of energy, but after a year or two it oozes 
out, though their spirit is still as zealous as ever." Two of the 
ministers spoke of the fact that when they came out they thought 
nothing of walking twenty miles, but now they dread the thought 
of two. Several of the most thoughtful and intelligent islanders, 
men who have succeeded in business and whose judgment would 
be respected anywhere, said: "We know that we are physically 
ttnable to do what English and Americans can do. We are weaker 
than our fathers, and they were weaker than theirs. It is a grief 
to send our children away, but in our hearts we know that this 
is not a white man's country." All this, it must be remembered, 
is not due to any specific disease, so far as we are aware. Indeed, 
I met several people who said that a stay of a few years in the 
Bahamas had improved their health, but at the same time had 
made them feel inefficient. 

Aside from extremely ignorant persons whose opinion is of 
little value, the only men who spoke of the climate more hope- 
fully were five or six highly trained officials and others occupy- 
ing positions of authority. These men, without exception, can 
control their own time. In most cases their office hours are from 
9 or 10 a.m. to 2 p.m., or less. They are men of naturally strong 
physique ; they have the opportunity and the will to take regular 
exercise ; and, most important of all, they make long and fre- 
quent visits to the United States or England. 

The benefit to be derived from a visit to a more bracing cli- 
mate is astonishing. The contrast between the dull, sallow com- 


plcxions and thin cheeks of the women and girls who have always 
lived on the islands and the round, rosy cheeks of those who 
have recently come back from a long stay at the North is most 
striking. According to a local saying you cannot tell whether a 
Bahaman woman is pretty until she goes away, and has a chance 
to fill out her cheeks and get some color. It is by no means strange 
that the stronger, more energetic young white people are fast 
leaving the islands. I asked a Bahaman girl, who had been study- 
ing nursing in New York, whether she enjoyed life more in the 
United States than in the Bahamas. "How can one help enjoying 
it more there?" she answered. "There one feels like doing things. 
Here one never feels like anything." Like almost everyone else 
she was sure that it was the climate even more than the new social 
environment which made the difference. 

One thing that surprised me was to hear the Bahamans speak 
of the stimulus of living in Florida. A native merchant remarked: 
"If I hire a new man I don't have to ask whether he has been to 
Florida. I know it by the way he works, but it docs not last 
long." Here again the social environment is an important factor, 
but various people told me that the air somehow makes them feel 
more capable of work in Florida than at home. The women of 
Florida I heard them say it themselves are pale and wan 
compared with their northern sisters. One of them, whose color 
still shows her northern origin, remarked: "When I come home 
after a summer in the North, I am full of energy and see all sorts 
of things that I want to change about the house. But after a 
month or two I don't care whether things are fixed or not." One 
hears the same sort of thing everywhere. A factory superin- 
tendent from Atlanta, Georgia, told me that the Florida work- 
men, even the most skillful mechanics, drive him frantic because 
they are so shiftless and so ready to take a day off whenever 
they feel like it far more so than at Atlanta, even though 
Atlanta seems slow to northerners. Yet, in spite of all these 
things, Florida is a more stimulating place than the Bahamas. 


Its summers are not much better, but its winters are sometimes 
frosty, while in the Bahamas the thermometer practically never 
goes below 50 F. Perhaps of greater importance, as we shall 
see later, is the fact that in Florida the temperature from day to 
day varies much more rapidly than in the Bahamas, even though 
both places are in the same latitude. Hence, the mainland is 
blessed with a genuine climatic stimulus compared with the uni- 
form islands. 

The last thing to be said about the Bahamas concerns the 
effect of the climate on mental activity. Practically all the 
islanders with whom I talked thought that the effect of the cli- 
mate on mental activity is at least as great as on physical. 
Several of the more thoughtful, without any suggestion on my 
part, put the matter in this way: "The worst thing about this 
climate is the effect on the mind. Not that people do not have as 
good minds as elsewhere, but one soon gets weary of hard mental 
effort. It is extremely difficult to concentrate one's thoughts. 
At night one cannot seem to make himself read anything serious 
nothing but the lightest kind of stories." In our own southern 
states one hears the same complaint. Even in Virginia the book- 
sellers say that during the long summer almost no one touches a 
serious book. One feels it everywhere, for on the trains, at the 
railroad stations, and at the newsdealers it is generally difficult 
to find the higher grade of magazines. Time and again during 
a recent journey of three months in the southern states I tried 
to get such papers as the Outlook, Independent, Harper's, At- 
lantic* Review of Reviews, The Century, and so forth but 
all that I could find was trashy story magazines. The dealers 
rarely keep the better magazines because people will not read 
them. Lack of training surely has something to do with the 
matter, but mental inertia due to lack of climatic stimulus seems 
to be at least equally important. 

Let us return now to our question as to a Teutonic and a 
negro Egypt. The farmers of the northern and southern states, 


the race problem of South Africa, and the backwardness of the 
Bahamas, all seem to point to the same conclusion. When the 
white man migrates to climates less stimulating than those of 
his original home, he appears to lose in both physical and mental 
energy. This leads to carelessness in matters of sanitation and 
food, and thus gives greater scope to the diseases which under 
any circumstances would find an easy prey in the weakened 
bodies. The combination of mental inertia and physical weakness 
makes it difficult to overcome the difficulties arising from isola- 
tion, from natural disasters, or from the presence of an inferior 
race, and this in turn leads to ignorance, prejudice, and idleness. 
Thus there arises a vicious circle which keeps on incessantly. 
From its revolving edge a part of the community is thrown off as 
poor whites, whose number increases in proportion to the ener- 
vating effect of the climate and the consequent speed with which 
the circle revolves. That climate is the original force which sets 
the wheel in motion seems to be evident, because it is only in 
adverse climates that we find the "cracker" type of "poor white 
trash" developing in appreciable numbers. If white men lived a 
thousand years in Egypt it seems probable that a large propor- 
tion of them would degenerate to this type. Whether they would 
still retain an inheritance of health and mentality sufficient to 
keep them ahead of a similar body of negroes can scarcely be 

The chief reason for doubt in this respect is that we do not 
yet know just how natural selection would work in such a case. 
It would almost certainly act in two ways. First, many of the 
abler young people of the white race would presumably migrate, 
as they do in the Bahamas. This tendency is generally strongest 
in the upper classes who can afford to send their children away 
to school. It is also strong among the young people of all classes 
who possess more than the average initiative, ambition, and 
physical strength. It becomes weaker and weaker as one goes 
down the scale, and almost ceases among the "poor whites," who 


have so little mental capacity and so much physical inertia 
that in spite of much grumbling they remain where they are 
and compete with the colored people. The other kind of natural 
selection consists of a selective death rate. Children who inherit 
certain physical and mental traits are more likely to die than 
are children who do not possess those traits. What the traits 
are which cause extermination we do not know. A fair skin, a 
nervous temperament, an excess of activity, and an unwilling- 
ness or incapacity to get sufficient rest may be qualities which 
doom certain white stocks to gradual extinction outside their 
own climate. In places like South Africa and the Bahamas the 
temperament which is willing to intermarry with the colored 
people helps certain types of white people to perpetuate their 
inheritance, but at the same time it gradually eliminates the 
qualities of energy, initiative, and inventiveness which seem to 
be so much more characteristic of Nordics than of negroes. 

It must not be forgotten that theoretically it may be possible 
that some day a carefully controlled series of crosses between 
whites and blacks may eliminate the weak traits of each and 
combine the good traits. Thus a race may arise which resembles 
negroes in its good temper and its capacity to withstand a 
tropical climate, but which will have the progressive, executive, 
and inventive capacities of the white race. Such crosses have 
been made among animals. For example, Mr. M. F. C. Honore 
of the Transvaal has sent me the following quotation which he 
believes to be prophetic of what will some day happen in South 
Africa. It is from Winston Churchill, the British Cabinet Minis- 
ter. "At Naivasha [practically on the equator in British East 
Africa] there is the Government stock farm. One may see in their 
various flocks, the native sheep, the half-bred English, the three 
quarter bred, etc. The improvement is amazing. The native 
sheep is a hairy animal, looking to the unpractised eye more 
like a goat than a sheep. Crossed with Sussex or Australian 
blood, his descendant is transformed into a woollen beast of 


familiar aspect. At the next cross the progeny is almost indis- 
tinguishable from the purebred English in appearance, but 
better adapted to the African sun and climate. It is the same 
with the cattle. In the first generation the hurnp of the African 
ox vanishes. In the second he emerges a respectable English 

Such carefully controlled crossbreeding may perhaps be 
possible among mankind after hundreds or thousands of years. 
But first we must know what human qualities are "unit char- 
acters" so that they are inherited according to the Mendelian 
law and are not due to the combination of a series of such char- 
acters. Then we must learn what qualities are dominant over 
others so that the presence of one hides the other. Another highly 
complex problem is to determine what qualities are linked with 
others so that one cannot be inherited without the other. The 
fact that linked qualities are very common may mean that cer- 
tain good qualities like the tolerance of the negro for a hot cli- 
mate can never be inherited without certain undesirable qualities 
like the lack of care for the future which is one of the chief causes 
of negro shiftlessness. Even if such linkage is not an insuperable 
barrier to the production of a really new race by intelligent 
crossbreeding there still remains the almost insurmountable 
obstacle of deep-seated human customs, racial antipathies, and 
modern ideas of individual liberty. Nevertheless, it is worth while 
to reflect on the following dream of Laf cadio Hearn : "It is 
neither unscientific nor unreasonable to suppose the world even- 
tually peopled by a race different from any now existing yet 
created by the blending of the best types of all races ; uniting 
western energy with far eastern patience, northern vigor with 
southern sensibility, the highest ethical feelings developed by all 
great religions with the largest mental faculties evolved by all 
civilizations ; speaking a single tongue composed from the richest 
and strongest elements of all preexisting human speech, and 


forming a society unimaginably superior yet unimaginably un- 
like to anything which now is or will ever be." 

This is an inspiring dream even though most biologists now 
regard it as impossible. So far as climate is concerned the hard 
reality seems to be that at present, both by its direct action and 
through natural selection a warm, monotonous, and unstimu- 
lating climate tends to reduce human activity both physical and 
mental, regardless of race. 


THUS far we have dealt with the temperate zone. Even the 
Bahamas lie north of the Tropic of Cancer. Let us now 
turn to the torrid zone, which contains the world's richest and 
most inviting fields of future development. Let us inquire into 
the effect of that region upon Europeans who attempt to live 
there permanently. The isolation of the tropical regions, their 
lack of facilities for transportation, and the great difficulties of 
agriculture will doubtless be overcome, but that will by no means 
solve the problem. Two great obstacles will still remain the 
native inhabitants and the white man's own mind and body. 

Whatever may be the cause, it is generally agreed that the 
native races within the tropics are dull in thought and slow in 
action. This is true not only of the African negroes, the South 
American Indians, and the people of the East Indies, but of the 
inhabitants of southern India and the Malay peninsula. Perhaps 
they will change, but the fact that the Indians both of Asia and 
South America have been influenced so little by from one to four 
hundred years of contact with the white man affords little 
ground for hope. Judging from the past, there is scant reason 
to think that their character is likely to change for many gen- 
erations. Until that time comes they will be one of the white 
man's greatest obstacles. Experience shows that the presence 
of an inferior race in large numbers tends constantly to lower 
the standards of the dominant race. Here in America, although 
the negro forms only a tenth part of the population, he is one 
of our gravest problems. Yet he is not so great a handicap as 


are the native races of the tropics. Whatever the negro may 
have been when he was first brought to America, he is now less 
stolid and indifferent, more subject to stimulating influences 
than he was when he came, or than the Indians of tropical 
America. It is literally true in South America, for instance, that 
the more an Indian is paid the less he will work. If one day's pay 
will buy two days' food, he will work half the time ; if the pay is 
increased so that one day's pay will buy food for three days, he 
will work one third of the time. The experiment has been tried 
again and again. The most considerate employers of tropical 
labor agree with the most inconsiderate that in general it is use- 
less to attempt to spur the Indians by any motive beyond the 
actual demands of food and shelter. Kindness and consideration 
on the part of the employer undoubtedly promote faithfulness, 
but they seem rarely to arouse ambition or energy. With the 
negro in Africa, as everyone knows, much the same condition 
prevails, but where he has been brought to the United States this 
is by no means so true. For example, in Central America it is 
generally thought that a negro from Jamaica is more efficient 
than an Indian, while a negro from the United States is much 
more efficient. The negro in the United States is generally con- 
sidered more efficient than he was in Africa, whereas his stay-at- 
home brother and the Indian of tropical America, remaining in 
their old environment, do not seem to have changed. 

Doubtless the change in the negro is due to a new social en- 
vironment quite as much as to a new physical environment, and 
many authorities believe that the social change is the more im- 
portant. This, however, does not materially alter the case. As 
conditions are now, it is extremely difficult to change the physical 
environment of tropical races so long as they remain in their 
present habitat, and it seems to be equally difficult to change 
their social environment. Those who dwell permanently in the 
white man's cities are influenced somewhat, but the results are 
often disastrous. Here as almost everywhere within twenty de- 


grees of the equator, the general tendency seems to be to revert 
to the original condition as soon as immediate contact with the 
white man is removed. 

This does not mean that contact with a higher civilization 
will never benefit the people of the tropics, but merely that the 
process is bound to be slow. The aborigines of tropical America, 
for example, show little sign either of disappearing, or being 
swallowed up by a multitude of immigrants, as has been the case 
in temperate latitudes, nor do they appear to be changing their 
character. On the contrary, in Latin America, the only tropical 
region except Australia where the white man has settled in large 
numbers, the proportion of Indian blood is apparently increas- 
ing at the expense of the white, and the Indians act and think 
almost like their ancestors three or four centuries ago. This is 
largely because the white man, except in a few favored places, 
suffers from tropical diseases more than does the native, and his 
children tend to move away if strong, or to be weaklings who die 
young and leave few children. It is notorious that India contains 
almost no fourth generation of Indian-born British. The British 
children are either sent back to Europe to recover their health, 
or else become enfeebled and their descendants die out. Even 
with the help of modern medical science, it is not yet certain that 
the permanent white population can increase greatly, although 
sojourners are sure to become numerous. In Australia, to be 
sure, the white man seems to be succeeding within the tropics, 
but he is still new there and has the inestimable advantage of 
active natural selection and freedom from contact with the 

In many well-populated tropical countries modern science 
lowers the death rate among the natives, and thus increases 
their numbers. The white man has permitted the native popula- 
tion of India to double and that of Java to increase seven-fold, 
partly by conquering diseases and partly by the prevention of 
famine and war. If the conclusion just reached is correct, it 


seems probable that tropical countries will long continue to 
maintain a dull, unprogressive population. Contact with such a 
population constantly exposes the white man to a most deterio- 
rating influence. For example, the inferior mental ability of the 
lower race, and its incapacity for effective organization lead to 
the abuse of its labor and to its exploitation in some form of 
peonage, even though the fact may be disguised by legal phrase- 
ology. Again, the presence of a despised race is almost certain 
to lead to low sexual morality. In the same way, political equal- 
ity becomes a mere form of speech, for the dominant race will 
not permit the other to gain rights at its expense. Manual labor, 
too, is despised, for it is associated with the idea of an inferior 
race. All these things may be looked upon as disadvantages of 
the lower race, but I believe that the higher reaps by far the 
greater injury. The conditions just mentioned appear to be 
among the most potent factors in rendering it difficult for the 
white man to attain as much success in tropical regions as in 
those farther to the north or south. Their evil effect is roughly 
proportional to the difference between the two races. That dif- 
ference is at a maximum where a low tropical race remains in 
its original, unstimulating environment, and is brought into 
contact with immigrants of a highly developed race who com- 
pletely change their environment. The newcomers are released 
from old restraints at a time when they stand in peculiar need 
of them. Instead of being stimulated to greater love of political 
freedom and equality, sterner morality, and more intense in- 
dustry, as was the case among the settlers in New England, the 
immigrants are in danger of being weakened in all of these re- 
spects. The effect on the original immigrants is bad enough, 
but on their children it is far worse. The settler, or European 
colonist, who is possessed of wealth and power, can to a slight 
degree shield his family, but even in such cases the children are 
'"n constant contact with servants. They grow up with a supreme 
contempt for the natives, and at the same time with the feeling 


that they can treat them as they choose. If poorer people, that 
is, colonists in the ordinary sense of the word, attempt to live in 
the tropics, especially if they are people who work with their 
hands, their children are exposed still more to all the con- 
taminating influences of contact with the natives. Hence, the 
second and third generations, and the fourth and fifth, if there 
are any, suffer more than their ancestors. 

The degree to which the indirect or external handicaps of 
tropical countries are effective in lowering the standards of 
civilization depends largely upon the amount of energy and 
will power possessed by the inhabitants. This, in turn, depends 
upon physiological conditions. Obviously, diseases have much 
to do with the matter. This subject has been so much discussed 
that I shall here refer to it only briefly. There can be little 
doubt that malaria and the many other diseases which are 
characteristic of tropical countries play an important part in 
causing a low state of civilization. The old idea that the people 
who live in tropical regions are immune to local diseases is no 
longer accepted by students of tropical medicine. Adults, to be 
sure, are often immune, but apparently this is only partially true 
of children. Vast numbers of children die in infancy and early 
childhood from the diseases which prevent the white man from 
permanently living within the tropics. Others suffer, but recover. 
They bear the results with them to the grave, however, in the 
form of enlarged spleens, or other injuries to the internal organs 
of the body. The world has of late been astonished at the ravages 
of pellagra and of other diseases due to such organisms as the 
hookworm. People who are subject to them cannot be highly 
competent. Their mental processes, as well as their physical 
activity, are dulled. So long as a community is constantly 
afflicted with such disorders, it can scarcely rise high in the 
scale of civilization. Nothing is more hopeful for the tropics 
than the rapid progress in the control of these diseases. If they 
could be eliminated, not only might the white man be able to 


live permanently where now he can be only a sojourner, but the 
native races would probably be greatly benefited. How great 
this benefit would be we cannot yet tell, but the elimination of 
the diseases which especially affect children would probably do 
much to increase vitality, energy, and initiative. This in itself 
would be an immeasurable boon not only to the natives, but to 
the white man, who would thereby be freed in part from some of 
his worst social dangers. 

This highly desirable result cannot be obtained quickly. The 
achievements of the United States in Panama are sometimes said 
to prove that diseases can be eliminated anywhere in tropical 
countries. This is true, but it must be remembered that Panama 
is a highly specialized case. During the building of the Canal 
a great number of people were collected in a small area, and 
enormous sums of money were freely expended. Everyone was 
subject to strict, semi-military rule, and similar conditions still 
continue. Such methods cannot be applied to millions of square 
miles. The expense would be prohibitive. The ordinary farmer 
in tropical regions cannot expect to be protected by his govern- 
ment. He must protect himself. In the long run even tropical 
races may learn this lesson, but it will be a difficult and expensive 
task, and will require a radical change in the people themselves. 
Such a change will doubtless come, but not for generations, and 
not until a long selective process has gone on whereby those 
who do not adopt modern medical methods will gradually be 
eliminated, while those who adopt them will persist. 

There has been so much misunderstanding of Panama and so 
many wild statements that it may be well to set forth the exact 
facts. The Health Department of the Panama Canal, as it is now 
called, has charge of three districts, whose population in 1917 
was as follows: the city of Panama, 61,074; the city of Colon, 
25,386 ; and the Canal Zone, 27,543. For purposes of health and 
sanitation all are under the control of the United States, and no 
expense is spared to make them as healthful as possible. In order 


to avoid the complications due to the influenza epidemic of 1918, 
let us take the period from 1912 to 1917. By 1912 the health 
measures of the United States Army had reached such perfection 
that the death rate had been reduced 50 per cent. The improve- 
ment still continues, but it is now slow and apparently does little 
more than keep pace with the similar improvement in the ad- 
vanced parts of the world. The two cities of Panama and Colon 
contain the ordinary mixed population of tropical seaports : 
negroes from the West Indies ; Mestizos half Spanish, half 
Indian from the neighboring parts of Central and South 
America ; a few Chinese and other Asiatics ; some Europeans and 
Americans. A considerable number of the employees of the Canal 
live there. The Canal Zone, on the other hand, contains a large 
proportion of Canal employees, chiefly Americans, West Indian 
negroes, and Europeans. Among all of these the percentage of 
men between twenty and fifty years of age is large. The follow- 
ing figures show the crude death rates from 1912 to 1917 among 
the civilian population, excluding soldiers, in the three districts 
of Panama and in certain other areas with which comparisons 
may profitably be made. 

Panama . 30.5 Chile . . . 27.9 Bombay (1910-1912) . . 37.0 
Colon . . 24.8 Spain . . . 22.0 Calcutta (1910-1912) . . 26.1 
Canal Zone. 13.6 United States . 13.9 Amsterdam (1901-1913) . 12.6 

A multitude of other figures might be presented all of which 
would show that while the work done in Panama has been ad- 
mirable, the general conditions of health in the cities of Panama 
and Colon are still twice as bad as in the advanced parts of the 
world. They are about on a par with those of similar cities of 
India, for Bombay and Calcutta, by reason of their size and 
desperate overcrowding, presumably have higher death rates 
than do Indian cities as small as Panama and Colon. The death 
rate for infants under one year bears out this general conclusion, 
as appears from the following figures showing the deaths per 
one thousand births in 1915, 1916, and 1917: 


Panama, Colon, and the Canal Zone 232 

Colored people in New York 182 

Colored people in United States Registration Area .... 172 

White people in United States Registration Area .... 96 

White people in Minnesota 69 

The area where births are registered in the United States in- 
cludes only a small part of the South, so that the death rate 
among colored infants as a whole is higher than appears above. 
In Richmond, Virginia, during 1917, 1918, and 1919, it aver- 
aged 198. In cities farther south it doubtless reaches a level as 
high as that for people of all sorts at Panama. 

The foregoing data make it obvious that the widespread idea 
as to the healthfullness of Panama is based solely on the small 
number of people in the Canal Zone. But the death rate of 13.6 
given above for the Canal Zone has by no means the significance 
that is usually supposed. Its use for comparative purposes is 
vitiated by two facts ; first, the number of deaths by violence, 
chiefly by accident, is unusually high in the Canal Zone ; and 
second, the inhabitants of the Canal Zone are a highly selected 
group mostly of good physique and in the prime of life and hence 
bound to have a relatively low death rate no matter where they 
live. The best way to make a fair comparison is to take people 
of the same age, sex, and occupation who have otherwise also 
been selected by the same method, and compare the death rates 
in different places. But this is impossible. As the next best thing 
let us take the death rate from 1912 to 1917 among the Canal's 
white employees from the United States and compare it with the 
rate for men of similar age elsewhere. If we assume that the pro- 
portion of white men of different ages in the Canal Zone is the 
same as among the white employees from the United States and 
was also the same at the census of 1920 as in the period from 
1912 to 1917, both of which are essentially the case, it is easy 
to compute the relative death rate in other regions on the same 
basis as the rate for Panama. Using the data prepared by the 
International Institute of Statistics together with the records 


of Yale University, we find that if the proportion of men of vari- 
ous ages were the same in the other places as among the white 
American employees of the Panama Canal, the death rates 
among such men would be as follows : 

Approximate death 

rate when deaths 
Death rate from due to violence 
all causes are eliminated 

New York State, 1906-1915 12.3 10.6 

Connecticut, 1906-1915 10.8 9.3 

Washington State, 1908-1913 7.8 5.3 

New Zealand, 1906-1915 6.7 4.8 

White Canal employees from the United 

States, 1912-1917 4.9 2.7 

Students in Yale University, 1912-1917 . . 1.9 1.7 

Does this mean that the climate of the states of New York and 
Connecticut is relatively bad, while that of Panama and the home 
of Yale University at New Haven is remarkably good? Not at 
all. It simply means that the two states have relatively normal 
death rates for their particular climates and for a comparatively 
unselected population. They are handicapped by their numer- 
ous unhealthful factories and cities and by the great number of 
their immigrants, many of whom are poor, ignorant, and of low 
caliber mentally. Moreover, many of the more energetic young 
people have migrated westward. The adventurous and persistent 
qualities which lead to migration are partly due to health and 
physical vigor, and partly to mental initiative, adaptability, and 
readiness to try a new life and new methods. It needs no demon- 
stration to show that such people are sure to have a low death 
rate, especially when they are highly prosperous, as in the state 
of Washington. They have the physical vigor to withstand dis- 
ease, they have the good sense to take care of themselves, and 
they have the means wherewith to purchase good food, good 
shelter, good sanitation, and good medical service. Since New 
Zealand is harder to reach than Washington, its immigrants 


have been even more highly selected for thrift, health, and 
physical and mental vigor. 

Panama, like Washington and New Zealand, attracts chiefly 
the more vigorous type of people. The man who is organically 
diseased rarely thinks of going there. Moreover, in Panama 
white employees come from America as adults. On the contrary, 
many of the people of Washington and New Zealand were born 
there and have remained regardless of whether they possess the 
pioneer vigor and initiative of their parents. Again, even if they 
have the brave spirit that overcomes physical handicaps, the or- 
ganically weak are not allowed to go to Panama as employees. 
If they try to go, they are weeded out by physical examinations. 
Even that, however, does not end the matter, for the examina- 
tions are repeated each year. Every individual who shows signs 
of weakness is advised to leave Panama as soon as possible; 
many are ordered home ; and not a few are deported, especially 
those suffering from mental disorders. During the three years 
for which I have been able to find data (1914, 1915, and 1917) 
the deportations on account of disease among employees of all 
sorts, both white and colored, amounted to approximately 40 
per cent of the total deaths from disease. If these people had 
stayed in Panama, as they stay in New York, Connecticut, 
Washington, or New Zealand, many of them would soon have 
died. Inasmuch as such deportations have been going on for 
years, it is practically certain that without them the death rate 
at Panama would be decidedly larger than now. In addition to 
the persons who are deported, a far larger number go home 
voluntarily on the advice of their physicians. Moreover, many 
who show no immediate signs of disease remain at home after 
one of their earlier furloughs because they find the climate at 
Panama uncomfortable. 

In addition to all this it must be remembered that the white 
employees at Panama are practically all officials or clerks ; they 
belong to a class of society which by reason of its intelligence is 


able to take care of itself, so that its death rate is normally much 
lower than that of the great body of men of similar age. More- 
over, the employees are well paid and admirably housed. They 
likewise have long and frequent vacations at home whereby the 
effect of the tropical climate is partially neutralized. All these 
conditions, even without the excellent medical care which the 
employees receive, free of cost, would insure a degree of health 
in Panama much better than in most tropical regions. On the 
other hand, if the population of Panama were an ordinary un- 
selected type and if none of the weak or sick were sent away, it 
seems probable that in spite of admirable sanitation and medical 
care the death rate would be larger than in New York among 
people of similar age. This last statement is merely an opinion, 
since by its very nature it is not susceptible of actual proof. We 
know as a fact, however, that the death rate at Panama is 
greatly lowered by the selection of healthy, intelligent employees 
as well as by good medical care. 

The conditions at Yale or any other university suggest that 
in such cases selection is even more important than medical care. 
From June, 1912, to June, 1917, the average number of under- 
graduates at Yale was 2476, among whom the total number of 
deaths was nine through disease and one by accident. This gives 
an annual death rate of 0.8 per thousand against 4.5 for all 
the young men of Connecticut between 15 and 24 years of age. 
In other words, an unselected young man in Connecticut is 5.6 
times as likely to die as is a selected Yale student. If a similar 
ratio prevailed among the University men up to the age of about 
55 years, and if the proportion of men at each age were the same 
as at Panama, their death rate, barring accidents, would be only 
1.7 against 2.7 among the white American employees at Panama. 
Now as a matter of fact, from the standpoint of health the 
employees at Panama are far more rigidly selected than are the 
Yale students. No medical examination is required for entrance 
to the University, no one is actually sent away because of his 


health, and the amount of medical attention is less on the whole 
than at Panama. Other things being equal, this ought to give a 
higher death rate at Yale than at Panama. Yet, as a matter of 
fact, it actually gives Panama the higher rate by 60 per cent. 
This turning of the tables against Panama seems to be due to the 
adverse climate. 

The net result of the preceding investigation is this : There 
can be no doubt of the great value and success of the medical and 
sanitary work at Panama. It has cut the death rate in halves at 
the cities of Panama and Colon. Nevertheless, the death rate in 
those cities is still extremely high, about twice that of the United 
States as a whole. So far as the white people at Panama are con- 
cerned, the death rate is very low, but that proves nothing about 
the climate. It merely proves that it is possible to obtain prac- 
tically any death rate by selecting the cases. One could go to 
hospitals and select the critical cases. That might give a death 
rate of eight or nine hundred. One might select college athletes 
and from time to time throw out any who showed signs of illness, 
and the death rate would be zero. But to use such death rates as 
evidence concerning the climate would be highly misleading. It 
is poor policy to use any such reasoning in respect to Panama, 
Northern Australia, or any other region where the climate pos- 
sesses disadvantages. To do so encourages false hopes. When 
these are disappointed, people tend to blame the whole science 
of tropical medicine. That science is doing wonderful things, 
but as yet there is no evidence that it has overcome the effects of 
climate, although it has certainly mitigated them. We shall re- 
turn to this subject in connection with Australia. There, as in 
Panama, the tropical death rate is lower than those of better 
climates, but this is due primarily to the selection of certain 
types of residents. I have dwelt on this matter because there is a 
vast deal of misapprehension and very little realization of the 
importance of selection. 

Let us return now to our main question. Suppose that the 


white man should succeed in cultivating the tropical forests, 
transversing the waste places, and conquering the diseases. Sup- 
pose also that he should eliminate the deteriorating influences of 
low social and moral standards among the natives. But suppose 
also that there were no selection of the white colonists. If all this 
were suddenly done, and average unselected white men were set 
down in a tropical garden of Eden, would they be able to hold 
their own among the peoples of the world? Would Teutons or 
Latins under such circumstances be able permanently to main- 
tain as high a standard of civilization as is maintained by their 
brothers in Europe? Or would there be a change in some of the 
traits which we are wont to call racial? Clearly we are back at 
the point where we started, and are confronted by the question 
of race versus place. We must determine how much of our Euro- 
pean and American energy, initiative, persistence, and other 
qualities upon which we so much pride ourselves is due to racial 
inheritance, and how much to residence under highly stimulating 
conditions of climate. 

One of the lines along which we may seek for an answer is by 
a comparison of the character of Europeans in tropical coun- 
tries with their character in the temperate zone. Whatever differ- 
ences we may find are presumably due partly to physiological 
and partly to sociological causes, but they manifest themselves 
chiefly through the will. In tropical countries weakness of will 
is unfortunately displayed not only by the natives, but by a 
large proportion of the northerner sojourners. It manifests 
itself in many ways. Four of these, namely, lack of industry, an 
irascible temper, drunkenness, and sexual indulgence are par- 
ticularly prominent, and may be taken as typical. Others, such 
as proneness to gambling and disregard for the truth, might 
equally well be considered if space allowed. 

In the quality of industry the difference between people in 
tropical and other countries is well known. We have already 
touched on it in the Bahamas, but let us amplify it further. 


Practically every northerner who goes to the torrid zone says at 
first that he works as well as at home, and that he finds the climate 
delightful. He may even be stimulated to unusual exertion. Little 
by little, however, even though he retains perfect health, he slows 
down. He does not work so hard as before, nor does the spirit of 
ambition prick him so keenly. On the low, damp seacoast, and 
still more in the lowland forests, the process of deterioration is 
relatively rapid, although its duration may vary enormously in 
different individuals. In the dry interior the process is slower, 
and on the high plateaus it may take many years. Both in books 
and in conversation with inhabitants of tropical regions one 
finds practical unanimity as to this tropical inertia, and it 
applies both to body and mind. After long sojourn in the tropics 
it is hard to spur one's self to the physical effort of a mountain 
climb, and equally hard to think out the steps in a long chain of 
reasoning. The mind, like the body, wants rest. Both can be 
spurred to activity, but this exhausts vitality. The common ex- 
planations of tropical inertia are diverse. One man says that 
within the tropics hard work is unnecessary, because salaries 
are high ; another asserts that it is because servants are cheap ; 
still another claims that hard work is dangerous to the health ; 
and almost all agree that "anyhow, one doesn't feel like working 
down here." Probably all four of these factors cooperate, and 
each, doubtless, produces pronounced results, but the last two, 
health and "feeling," seem the most important. 

In spite of individual exceptions, white men who spur them- 
selves to exert their minds as earnestly and steadily within the 
tropics as at home are in great danger of breaking down in 
health. They become nervous and enfeebled, and readily suc- 
cumb to tropical diseases. This is one of the most powerful 
deterrents to the development of an efficient white population 
in equatorial regions. If the more intellectual members of the 
community ruin their health, they are almost sure to die before 
their time, or else to go back to the North. In either case they 


are not likely to leave many children to perpetuate their char- 
acteristics. Thus if white colonization takes place on a large 
scale within the tropics, there is grave danger that the physically 
strong but mentally lethargic elements will be the ones to be- 
come the ancestors of the future population. In the past this 
factor must have operated to weed out the more intellectual 
members of each of the many races that have migrated toward 
the equator. The inertia which prevents the less competent mem- 
bers of a tropical community from overworking may perhaps 
be interpreted by teleologists as a merciful provision of Provi- 
dence to warn man that he must not work too hard in the torrid 
zone, but that will scarcely help to advance civilization. Few 
people will question the reality of the tropical inertia. It is the 
same lassitude which everyone feels on a hot summer day the 
inclination to sit down and dream, the tendency to hesitate 
before beginning a piece of work, and to refrain from plunging 
into the midst of it in the energetic way which seems natural 
under more stimulating conditions. 

Lack of will power is shown by northerners in tropical regions 
not only in loss of energy and ambition, but in fits of anger. The 
English official who returns from India is commonly described 
as "choleric." Every traveler in tropical countries knows that 
he sometimes bursts into anger in a way that makes him utterly 
ashamed, and which he would scarcely believe possible at home. 
Almost any American or European who has traveled or resided 
within the tropics will confess that he has occasionally flown 
into a passion, and perhaps used physical violence, under cir- 
cumstances which at home would merely have made him vexed. 
This is due apparently to four chief causes. One is the ordinary 
tropical diseases, for when a man has a touch of fever, his temper 
is apt to get the better of him. In the second place, the slowness 
of tropical people is terribly exasperating. The impatient north- 
erner uses every possible means to make the natives hurry, or to 
compel them to keep their word. His energy is usually wasted 


the native remains unmoved, and the only visible result is an 
angry and ridiculous foreigner. Yet a show of anger and violence 
often seems to be the only way of getting things done, and this is 
frequently used as an excuse for lack of self-control. In the 
third place, the consequences of becoming angry arc less dan- 
gerous than elsewhere. The inert people of tropical countries 
often submit to indignities which an ordinary white man would 
bitterly resent. Of course they object to ill treatment, and will 
retaliate if possible, but they generally do not have sufficient 
energy or cunning to make their vengeance effective against the 
powerful white man. Finally, those who have lived in the tropics 
generally find that, even when things go smoothly, and they are 
in contact with people of their own kind and are in compara- 
tively good health, they are more irritable than at home. In 
other words, their power of self-control is enfeebled. Of course 
there are many exceptions, but that does not affect the genera] 

Drunkenness, our third evidence of lack of self-control, need 
scarcely be discussed. Within the tropics, the white man's alco- 
hol in the form of rum is scarcely more injurious to the natives 
of Africa than it is in other forms to himself. In places such as 
Guatemala and parts of Mexico, drunken men and women may 
be seen upon the streets at almost any time of day. Nowhere else, 
during extensive travels in America, Europe, and Asia, have I 
seen so much drunkenness as in Guatemala. Among white men a 
large number drink as badly as the natives. Here is an example ; 
a railway conductor was telling me about drinks in Guatemala: 

"They've got something here called 'white-eye,' " he remarked. 
"You know that Mexican 'mescal,' and how strong it is? Well, 
white-eye's got mescal chained to a telegraph pole. Yes, I drink 
it. A man's got to drink something. The first time I tried it, I 
got crazy drunk and smashed things up the way they all do. I 
was arrested and fined fifty dollars. [This is really only two and 
a half, for Guatemalan currency consists of non-redeemable 


paper, which at that time was worth about five cents on a dollar 
a characteristic evidence of tropical incapacity.] I got fined 
several times that way and didn't like it. Then one day when I 
was going to get drunk, I said to myself, Til go and pay my fine 
now and then they won't bother me.' I did that several times, and 
the *jefe politico' liked it [presumably because it was an easy 
way of pocketing the money]. Then he said to the police : 'Don't 
bother this man. Just let him get drunk all he likes, and he'll pay 
his fines at the proper time.' I tell you, white-eye is bad stuff. 
The only proper way to drink it is to take a quart bottle in the 
morning. Find a place that will stay shady all day. Drink the 
whole thing right down and get so dead drunk that you will 
sleep till night." 

I do not cite this man as typical of all the white men in the 
tropics. Far from it. Many conduct themselves with sobriety 
and industry, but such men almost invariably make frequent and 
protracted visits to the better climate of the North. If a white 
man stays steadily for long periods in the tropics, however, and 
if his character has any weak spots, they are almost sure to be 
exaggerated. The drunkenness of the tropical white man arises 
in part from the constant heat, which makes people want some- 
thing to drink at all times, partly from the monotony of life, 
and still more from the absence of the social restraints which 
exercise so powerful an inhibitory influence at home. Back of all 
these things, however, among both the white men and natives, 
there seem to lie two conditions which arc directly connected 
with the climate. One is the same cnfecblement of the will which 
makes a man burst into anger. The other is a constant feeling 
of inefficiency which makes a man crave something to brace 
him up. 

The last of the ways in which weakness of will is evident in 
tropical countries is the relation of the sexes. Its importance can 
scarcely be overestimated. It leads to the ruin of thousands of 
northerners, even though they do not yield to drink, to anger, 


or to laziness. When once they have fallen into pronounced im- 
morality the other weaknesses soon follow. The condition of the 
native races is still worse. Everywhere within the tropics mis- 
sionaries say that their converts can be taught honesty, in- 
dustry, and many other virtues, but that even the strongest find 
it almost impossible to resist the temptations of sex. Many 
Europeans condone this. They say that it is natural, and that 
the natives had better be left to their own conventional ways of 
restricting but not preventing sexual intercourse. Perhaps they 
are right, although I cannot be certain. That is not the point, 
however. We are at present concerned with the effect which free 
indulgence has upon civilization and upon the capacity for 
progress. This may be illustrated by what Gouldsbury and 
Sheane, for example, say of the Zulus in northern Rhodesia. 
They hold that one of the greatest reasons why these people 
remain so backward is that their thought and energy are largely 
swallowed up in matters of sex. During the years when the 
young men ought to be getting new ideas and thinking out the 
many little projects and the few great ones which combine to 
cause progress, the vast majority are thinking of women, and 
planning to gain possession of some new woman or girl. Under 
such circumstances no race can rise to any high position. 

The causes of these conditions are various. Many writers dis- 
miss the matter by saying that the social standards of tropical 
people are low and tend to cause northerners to conform to them. 
This is true, but it explains nothing. A real, though minor, rea- 
son for the lowness of the standards is found in the free, open 
life which is almost universal within the tropics. People are out 
of doors so much and it is so easy to meet in secret that tempta- 
tion arises very frequently. Much more important is the scanty 
dress of the women, and its character, which calls attention to 
their sex. Livingstone speaks with disgust of the way in which 
his carriers, hour after hour, discussed the breasts of the half- 
naked women whom they met. Even in the North women seem to 


be strangely indifferent to the effect of their mode of dress upon 
men. They do not seem to think that they are responsible if their 
low-necked gowns and the making of their clothing in such a 
way that each little movement of their bodies can be detected, 
stir men's passions. They appear oblivious to the fact that the 
display of their beauty often means that some other woman must 
pay the penalty. Within the tropics these conditions are exag- 
gerated. I believe I am speaking within bounds when I say that 
any young man of European race with red blood in his veins is 
in more danger of deteriorating in character and efficiency be- 
cause of the women of the tropics than from any other single 

The strength of this deteriorating force is not merely exter- 
nal. Either the actual temptation to sexual excess is greater 
in the tropics than elsewhere, or else the inhibitory forces are 
weakened by the same processes which cause people to drink to 
excess, to become unduly angry, and to work slowly. Hcllpach 
states that it is said that in southern Italy sexual irregularities 
increase greatly at times when the hot, damp wind known as 
the sirocco blows across the Mediterranean from the deserts 
of northern Africa. This is so well recognized among the people 
themselves that offenses committed under such circumstances 
are in a measure condoned. Violence, too, is more common at 
such times, for self-control of every kind is weakened. In eastern 
Turkey the hot desert winds cause the whole community to be- 
come cross and irritable. I have there seen a missionary, a man of 
unusual strength of character, shut himself up in his study all 
day, because he knew that he was in danger of saying something 
disagreeable. I cite this case because, among the people whom I 
have known, missionaries are, on the whole, most completely 
masters of themselves and the least likely to let minor circum- 
stances turn them from the Christlike lives which they are striv- 
ing to live day by day before the native communities. For this 
same reason, to return to our immediate subject, I quote the 


remark of a missionary in Central America when we were dis- 
cussing the morality of the country. He was a most austere man, 
a member of a small and extremely devout sect, and his whole 
being was devoted to preaching the gospel. Speaking of his own 
experiences, he said: 

"When I am in this country, evil spirits seem to attack me. 
I suppose you would call them something else, but that is what 
I think they are. When I am at home in the United States I feel 
pure and true, but when I come here, it seems as if lust were 
written in the very faces of the people." 

In all the evils which have just been mentioned laziness, 
anger, drunkenness, and immorality social causes undoubtedly 
play an important part. A strong public opinion would save 
many a young northerner from drink and immorality, and would 
keep him faithful to his work. A clear religious faith or a high 
ideal of duty would do the same thing. Good homes, proper dress, 
and many other material changes would help greatly. So, too, 
would a study of how it has come to pass that certain tropical 
races, in spite of their environment, have developed compara- 
tively high moral codes to which they strictly adhere, while a 
few have actually learned the lesson of industry. Along with the 
social aspect of the question, however, and neither more nor 
less important, goes the physical. We must discover to exactly 
what extent physical conditions help or hinder the development 
of strong character. That is the purpose of the chapters that 



IN comparing Teutons with negroes, or tropical people with 
those of the temperate zone, we have been following a method 
as old as the days of Aristotle. Such comparisons have led to 
most interesting generalizations not only at the hands of Aris- 
totle himself, but of many other men such as Montesquieu, Hurn- 
boldt, and Ratzel. Yet the importance of climate as a factor in 
civilization is still in doubt. For instance, no one denies that 
South Africa is confronted by a grave race problem, but many 
say that it is purely economic, and has nothing to do with cli- 
mate. They support this view by strong arguments. Thus we 
are left in uncertainty. The only way to remove this is to devise 
some method whereby to separate the effects of climate from 
those due to all other causes, whether economic, historic, social, 
religious, racial, or something else. Accordingly, the rest of this 
volume will be devoted to an investigation of the exact effect of 
various climatic factors upon selected groups of people, and to 
an attempt to discover how human energy and other qualities 
would be distributed if all the earth's inhabitants were influenced 
like these particular groups. 

In the study of climate one of the most puzzling features is 
the diversity of opinion among persons of good judgment. For 
instance, at what season do people work fastest in the northern 
United States? Some will say the winter, some the spring, a 
considerable number the fall, and a few the summer. Most will 
say that they are least efficient in summer, but others believe 
that they are at their worst in the early spring or late winter. 


Again, ask a dozen friends whether they work best on clear days 
or cloudy. The majority will probably answer that the first clear 
day after a storm is by all means the best. A small number will 
perhaps think the matter over more carefully, and then say that 
after a storm the clearness of the air and the brightness of the 
sun are certainly inspiring, but one really accomplishes more 
when it rains. 

This divergence of opinion is due largely to the fact that 
climatic effects are of two kinds, psychological and physiologi- 
cal. We are always conscious of the first, but often unconscious 
of the second. The two are admirably distinguished in Hellpach's 
book on Geopsychische Erscheinungen. An example will make 
the matter clear. It is well known that at high altitudes the num- 
ber of red corpuscles in the blood increases enormously, and 
the capacity to absorb oxygen and to give out carbon dioxide 
is correspondingly modified. Yet many people can go to altitudes 
of 5000 feet or more without realizing that their physiological 
functions have been altered. To cite my own case, up to the age 
of twenty-one I had never been a thousand feet above the sea. 
Then I went to live at an altitude of 4500 feet. The only physio- 
logical effect of which I was conscious was unusual sleepiness for 
the first few months, but whether this was due to the altitude or 
to the dryness of the air, I do not know. For two or three years 
I never thought of the physiological effect of the altitude until 
one day, happening to have climbed to a height of 7000 feet, I 
began to run up hill. I lost my breath and became tired so quickly 
that I was alarmed and thought I must be sick. I was much re- 
lieved when it occurred to me that the altitude was not favorable 
for running up hill. Manifestly my physiological functions were 
different from what they were at sea level, although I was un- 
conscious of it. On the other hand, psychologically I was daily 
conscious of living in a place where the air was extraordinarily 
clear, and where the mountains were always in sight across a 
splendid plain twelve hundred feet below us. Presumably both 


the physiological and psychological conditions had an appre- 
ciable effect upon the work of every day, but which was the 
greater it is impossible to tell. 

In this connection Lchmann and Pcdersen state an interesting 
fact. In Denmark and Norway they made a series of daily tests 
of the strength of three individuals by means of a dynamometer. 
They found that the change of atmospheric pressure due to an 
ascent of two or three thousand feet makes no appreciable dif- 
ference. A similar descent, however, is accompanied by a marked 
increase of strength which disappears within three or four days. 
They suggest that this may be due to the persistence of abun- 
dant red corpuscles when people come down from high places. 
The red corpuscles multiply very rapidly under the influence 
of low pressure, but are slower in disappearing when the pres- 
sure once more increases. Thus, for the first day or two after a 
person has come down from the mountains, more than the normal 
amount of oxygen may be absorbed, and muscular strength 
correspondingly increased. Possibly this is why mountaineers are 
generally so irresistible when they descend upon the plains in 
sudden raids. My colleague, Prof. H. E. Gregory, suggests 
that this may account for the fact that in the horse-races of 
the pioneer days of the southwestern United States, the poor, 
scrawny animals brought down from the mountains by the In- 
dians usually belied their appearance and outran the better- 
looking animals of the white men. They may have had an excess 
of red corpuscles. Professor Gregory adds that in some of the 
highland regions of South America there is a strict rule that 
before a race the competing horses must spend a certain number 
of days at the race course. This may have arisen because the 
animals which race directly after coming from the mountains 
are apt to win. There is considerable doubt as to the truth of 
this theory, but it illustrates the possibility that we may be 
deeply influenced by atmospheric conditions of which we are 
almost unconscious. 


In our opinions as to the effect of the seasons or of daily 
changes of weather the relation between psychological and 
physiological influences is probably the same as in the case of 
altitude. The external conditions which we see and feel make 
a greater impression than those which prevail within our bodies. 
For example, most of us think that in the northern United States 
we work fast in winter. As a matter of fact, the statistics of ten 
thousand people show that we work slowly. The ordinary im- 
pression is apparently psychological. In order to keep warm 
out of doors in winter we walk fast and this leads us to think 
that we do everything rapidly. 

Again, the blue sky, clear air, bright sunshine, and fresh 
colors of the first day after a storm are unquestionably inspir- 
ing, but does that inspiration make us work any better? May it 
not lead to a nervous excitement which actually hinders our 
work, by causing us to look out at the beauties of nature or to 
be less concentrated in other ways? The actual figures show that, 
taking the year as a whole, on dull days, especially the second 
such day when a storm begins to clear, we accomplish more than 
on bright days, even though we grumble about the clouds and 
the dampness. A bright day certainly makes us cheerful, but its 
chief helpfulness, so far as our work is concerned, is felt when 
it is a change from the monotony of a series of dull days. Clouds 
and rain produce exactly as much rejoicing when they succeed 
prolonged clear weather of the kind that we praise so highly. In 
America I have never seen so much rejoicing over a bright day 
as I have seen in Turkey when the first rain fell after the long 
subtropical summer with its truly superb weather. The rejoic- 
ing was in part due to the fact that the coming of the rains means 
good crops, but I have again and again seen exuberant joy 
among people to whom the crops made no difference whatever. 
I have seen Americans shout for joy because the clouds had 
come, and run out into the rain to let the cool drops refresh 
their faces. 


The questions which have just been asked and the possibili- 
ties that have been suggested show how indefinite are our ideas 
of the effect of climate. We understand its psychological effects 
fairly well. We know little of its physiological effects, however, 
except when they are extreme or unusual, or when people are 
sick or are in some other pathological condition. We need to 
determine how ordinary people are influenced by ordinary con- 
ditions of weather. That is the purpose of our present discus- 
sion. The most feasible way to do this, as has already been said, 
is to take groups of people who live in a variable climate, and 
measure their efficiency under different conditions of weather. 
The best and fullest test of efficiency is a person's daily work. 
If the subject does not know that he is being tested, so much 
the better. Piece-workers in factories are doing exactly what is 
required for our purpose. Accordingly, to begin with New Eng- 
land, I have taken the daily records of about 300 men and 250 
girls, most of them for a complete year. The records are dis- 
tributed over the four years from 1910 to 1913. The 550 people 
were emplo^yed in three factories in the cities of Bridgeport, 
New Britain, and New Haven, in the southwestern part of Con- 
necticut. In all cases the officials in charge of the factories were 
most courteous and helpful in assisting me to obtain the neces- 
sary data, and I wish most warmly to express my gratitude to 
all concerned. 

In the selection of operatives for such a purpose, various con- 
ditions must be fulfilled. In the first place, they must be piece- 
workers who are paid according to their work and not at a fixed 
rate per day. In the second place, they must be employed in 
factories where their output is not limited by restrictions im- 
posed by unions, or by the fear that if they earn too much, wages 
will be reduced. They must be doing work that is of essentially 
the same kind every day, so that their wages will not vary much 
because thev are sometimes engaged upon new and unfamiliar 
tasks, or upon easy tasks at some times and hard ones at others. 


Furthermore, the same people must work steadily for month 
after month, throughout the year, if possible, and without tak- 
ing much time off, as is such a common practice among factory 
hands. Finally, they must be working where there is abundant 
incentive to steady, faithful work, where the conditions of air 
and light are reasonably good, and where accurate daily records 
make it possible to determine not only the daily wages of each 
individual but the average efficiency per hour or per day of 
standard length. The number of factories where all these condi- 
tions are fulfilled is small, for they demand special types of 
occupation and a high standard of management. The three 
factories from which data have been obtained all meet the re- 
quirements. I explained what I wanted to the superintendent 
or to some other responsible official in each case. He then selected 
the group or groups of operatives whom he thought proper, and 
placed the figures in my hands. There was no selection on my 
part, and in each case I have used all the figures, omitting only 
a few obvious errors amounting to perhaps a quarter of one 
per cent. 

An investigation such as is here set forth may follow two 
modes of procedure. One is to take a few persons and investigate 
each minutely in order to eliminate all accidental variations. 
The other is to take many people and get rid of the personal 
variations by averages. The wages of a workman depend upon 
many factors aside from the weather. One man has been scolded 
by his wife because he did not earn enough last week, another 
wants to buy some clothes for his little boy, and a third was 
drunk last night. A sore toe may have far more influence than 
any possible climatic variation. To ferret out all these accidental 
circumstances is out of the question. Fortunately, they do not 
occur every day, and most people work weeks at a time without 
being much influenced by them. Moreover, when large numbers 
of people work in different cities and during different years, the 
individual circumstances neutralize one another. The dav that 


John Jenkins is disturbed because his boy has run away, Tony 
Albano is working hard because he is going to be married. Hence, 
by taking five hundred people we are able to eliminate accidental 
and individual circumstances and thus to reach a reliable result. 
All three of the factories whence our data are obtained make 
hardware, but the work varies greatly. In one factory where 
Italians are the predominant nationality, brass sockets for elec- 
tric lights, and other little brass fittings are made. One group of 
people was here engaged in tending machines. Some were turn- 
ing out screws, others were putting pieces of sheet brass into 
automatic machines which turn out perforated plates. The work 
requires little skill, but much quickness and concentration. An- 
other group, composed largely of Italians, was engaged in roll- 
ing and drawing hot brass, a heavy and somewhat difficult kind 
of work, requiring considerable strength. It is difficult because 
the brass must be used hot, and hence the men must work in 
abnormally high temperatures. At another factory, the one 
from which the largest number of records was obtained during 
three successive years, there were two main groups of men and 
two of women. The girls, from sixteen to twenty years of age, 
were Americans by birth, but of varied descent, being chiefly 
Irish, Germans, Scandinavians, English, and other north Euro- 
peans. Their work was the packing of hinges and screws, which 
are first wrapped in tissue paper and then placed in pasteboard 
boxes. This is a light, easy task in which dexterity and accuracy 
in picking up the right number of pieces are particularly im- 
portant. For the first week or two when screws are packed, the 
tips of the fingers become sore, which makes the work proceed 
slowly. If a girl is changed from packing hinges to packing 
screws, her wages fall off for a time, but such changes are not 
frequent, and do not appreciably influence our figures. The men 
at this factory were of all ages, and were of the same races as 
the girls. They were engaged in grinding and buffing the hinges. 
The first operation is hard, heavy work. The hinges are held 


upon rapidly revolving emery wheels in order to grind them to 
a smooth surface. The other operation, buffing, is similar except 
that it is easier, for the hinges after being ground are polished 
upon rapidly revolving cloth buffs covered with emery dust. In 
the third factory, the operatives were of north European de- 
scent, almost all being native-born. Practically all, both girls and 
boys, were young, only a few being much over twenty years of 
age. The older girls leave to be married, and the boys, who are 
comparatively few in number, go elsewhere to find harder and 
hence better paid work. The work consists of the preparation 
of armatures and other wire coils for electrical purposes. Some 
operatives wind the wire upon rapidly revolving spools. Others 
put together the various parts of an armature. The work is 
light and not tiresome. It requires much dexterity and accuracy. 
Strings have to be tied at particular spots, pieces of paper must 
be inserted, the machines must be stopped when the right point 
has been reached, and little ends have to be grasped and inserted 
in their proper places. Taking our three factories together, the 
work ranges from the hardest to the lightest. It is of many 
kinds, requiring different degrees of strength and skill. The 
wages depend not only upon the amount of work completed, but 
upon the number of pieces rejected. In other words, the wages 
represent not only speed, but accuracy. 

Let us now turn to the actual performance of the operatives. 
This is summed up in Figure 1. The four upper solid lines repre- 
sent the work done week after week, each year from 1910 to 
1913. In Figure 1 the work of only about 410 people has been 
used. The rest have been omitted because the figures are not 
complete for a whole year. In only one case has there been a 
deliberate omission of figures which cover an entire year. That 
was the Italians who draw hot brass and hence are subject to 
abnormal conditions of temperature. The method of procedure 
has been to find for each working day the average hourly wages 
for each group of operatives. Hourly wages have been used in- 

Jan Feh Mck Apr May Jirte. Jify Avy&pt Oet Nw.D**. 


Figure 1. 'I'hc Effect of the Seasons on Factory Operatives in 
Connecticut (solid lines) and at Pittsburgh (dotted lines) 


stead of daity, so as to make it possible to compare half-days 
with whole. If part of the operatives were absent on any par- 
ticular day, they were simply omitted, and the average for the 
rest was taken. When the daily averages had been found, they 
were averaged together by weeks. In doing this, a half-day, such 
as the Saturdays in summer, was given only half as much weight 
as a whole day, and days when part of the operatives were absent 
or when the machinery was shut down for a while, were given a 
correspondingly smaller weight. Thus allowance is everywhere 
made for irregularities in the number of employees and the length 
of time that they work. The final process consisted of combining 
the different groups. In order that each individual may have the 
same importance, all the figures have been reduced to per- 
centages. In this way if a girl earned a maximum wage of twelve 
cents an hour, it is called 100 per cent, while if a man's maxi- 
mum wages were thirty cents, this sum also is called 100 per cent. 
Thus the variations in the wages of the girl and the man have 
the same weight in our final computations. Because of the enor- 
mous amount of work which would have been entailed, it was 
not possible to reduce the wages of each individual to percent- 
ages, but only those of each group. Had it been possible to work 
out each individual's wages separately, the results shown in our 
curves would probably have been more striking than is now 
the case. 

In Figure 1 the height of the curves indicates the efficiency 
of the operatives at various seasons for four successive years. 
The fifth curve, heavier than the others, is the average of the 
preceding four. Turning to the upper line, we see that in early 
January, 1910, the efficiency of about 60 factory operatives in 
Bridgeport was 88 per cent as much as during the week of 
maximum efficiency that year. By the middle of the month it 
had fallen to 86 per cent. Later it rose fairly steadily to 96 
per cent at the end of April. Then it dropped a little, rose still 
higher in June, and fell off distinctly during the summer, but 


not so low as in winter. During the autumn it rose steadily until 
early November, when it reached the highest point of the year, 
after which it fell rapidly. In the same way each curve may be 
traced week by week. I shall return to them shortly. Meanwhile, 
it would be advantageous for the reader to look them over and 
draw his own conclusions, picking out the features which are 
common to all, and noting those which show different degrees 
of intensity from year to year. 

In Figure 1 it will be noticed that the solid lines never reach 
100 per cent. This is partly because they have been smoothed, 
and partly because they have been corrected to compensate for 
the increased efficiency due to practice. The process of smooth- 
ing, as everyone knows, is used by mathematicians to eliminate 
minor variations and thus permit the main trend of a curve to 
be more apparent. It merely takes off the high points and the 
low. The figures for three weeks are averaged, and the average 
is used instead of the original figure for the middle week. In the 
present case, and in practically all the curves in this book, the 
process of smoothing has been performed twice on each curve. 
If the letters a to e represent the average wages for five suc- 
cessive weeks, the figure actually used for the middle week, c, 
is obtained from the following equation : 

a -f 2b + 3c + 2d + e 

This process of smoothing can add nothing to a curve ; it simply 
takes away the less important details. If carried far enough it 
would produce straight lines. 

In addition to smoothing the curves I have corrected them 
for the effects of practice. The curves for 1911, and 1912, and 
1913 are all based on the same factory at New Britain. When 
the wages for each year are averaged, we find that those for 

1912 were 1.5 per cent higher than for 1911, and those for 

1913 were 1.5 per cent higher than for 1912. This means that 


constant practice caused the average employee, including both 
old hands and new, to be 1.5 per cent more skillful at the end of 
the year than at the beginning. Hence, from January onward, 
the curve rises a little until in December it is 1.5 per cent higher 
than it would be if the operatives had not grown more skillful. 
To eliminate this we simply tip the entire curve, raising the 
January end by three quarters of one per cent and depressing 
the December end by the same amount. The fluctuations, of 
course, remain unchanged. 

In Figure 1, if there had been no correction, the highest and 
lowest points of the upper curve would lie at the points indi- 
cated by the crosses, and the other curves would be changed in 
corresponding ratios, there being no change at the end of June. 

Turning to less technical matters, let us consider the degree 
of resemblance in the four upper solid lines of Figure 1. All are 
unmistakably low in January. Then from February to June 
we note a general rise, varied by minor fluctuations which differ 
from year to year. At the middle or end of June all reach a 
distinct maximum, although in 1912 and 1913 it is of slight 
proportions. Next we have a drop during the summer, pro- 
nounced in 1910 and 1911, but not at all prominent in 1912, and 
scarcely noticeable in 1913. Following this there comes a series 
of irregular fluctuations, differing from curve to curve, but in 
each case culminating in a strong maximum at the end of Octo- 
ber or the beginning of November. Six weeks later, in the middle 
of December, another slight maximum is suggested, and then 
all the curves drop suddenly. In the average curve the minor 
fluctuations tend to disappear. They are more or less accidental, 
and represent peculiar conditions which pertain to one year but 
not to others. The features that have been named, however, show 
no sign of disappearing. They are five in number, namely, an 
extremely low place in midwinter, and a less pronounced low 
place in midsummer ; a high point in June, a still higher point at 
the end of October, and a hump in mid-December. Much the most 


variable feature is the low place in summer. This is highly sig- 
nificant, as we shall shortly see. 

Before we discuss the causes of the variability of the summers 
let us consider the meaning of the curves as a whole. In the first 
place, it is evident that, although details may vary from year 
to year, the general course of events is uniformly from low in 
the winter to high in the fall with a drop of more or less mag- 
nitude in summer. To what can this be due? Did the factories 
shut down in January, or run on part time, or decrease work 
because of lack of orders, or to overhaul the machinery and so 
forth? Do the high wages in October and November indicate a 
special rush of orders at that time? Of course, any variations 
in the way in which the factor}^ is running must be reflected in 
the wages of the operatives, but in the present case this does not 
apply to the main variations, although it may apply to minor 
details. In neither of the two factories here considered were the 
responsible heads able to offer any explanation of the peculi- 
arities of the curves on the basis of facto ry management or the 
exigencies of business. Both are engaged in making staple arti- 
cles, the chief demand for which comes in the spring when build- 
ing operations begin. There is no Christmas rush on hinges and 
electric light sockets. After Christmas the factories shut down 
for a few days at the beginning of the year, but that ought to 
increase rather than diminish the hourly earnings. When opera- 
tives are working only part time they feel the need of earning 
as much as possible each hour. If part of the hands are laid off, 
that would also increase the average hourly wages, for the 
weaker ones would be dropped, and the average ability of those 
who remain would be high. 

In this connection, it is important to understand that in 
these factories a man is free to work as hard as he wishes at any 
time of the year. The managers have deliberately adopted the 
policy of getting as much work as possible out of each opera- 
tive. Overhead charges for interest, superintendence, bookkeep- 


ing, salesmen, and other outside expenses, and also the charges 
for unproductive labor such as engineers, janitors, and the like 
are no greater no matter how hard the productive employees 
work. If the producing operatives should double their output, 
most of the other expenses would scarcely increase at all. Hence, 
it would not only be possible to pay double wages for double 
work, but it would be profitable to the factory even if it paid 
perhaps $2.50 where now it pays $1.00. In view of these condi- 
tions, both factories have adopted systems whose special object 
is to encourage extra exertion. In one case, part of the men work 
upon what is known as the "premium" plan. The management 
and the men have agreed that the various tasks shall be rated 
according to the number of hours which they may fairly be sup- 
posed to require. If a man performs an eight-hour task, he is to 
be paid for eight hours' work, no matter whether he does it in 
six hours or ten. If, however, he finishes the work in less than the 
stipulated time, he goes to work at another task for the rest of 
the period. For half of this time he is to be paid, while the factory 
gets the benefit of the other half. For example, if an eight-hour 
task is finished in six, the operative works two more hours. He 
is then paid for nine hours although he has only worked eight, 
while the factory gets ten hours' work and pays for nine. Thus 
both are the gainers. In one case the managers made a mistake 
in deciding upon the number of hours needed for a certain task. 
It had never been done quickly, and no one knew how rapidly it 
might be done. The man who does it soon earned ten or twelve 
dollars a day, where he formerly earned perhaps two and a half 
or three. Inasmuch as the management had agreed not to change 
the rates, they stuck to their bargain. The task only occupies 
one day each month, and the matter is not serious. Moreover, 
even though the operative earns such high wages, the work 
actually costs the factory less than when he was earning two 
dollars and a half. 

In the other factory the girls are stimulated by bonuses. That 


is, they are not only paid for their work, but if they do more 
than is expected they are paid a bonus. For example, if a girPs 
wages averaged about a dollar a day, and she did work worth 
$1.20, she did not receive $1.20, but $1.25 or even $1.40. The 
factory finds this worth while because so much more can be pro- 
duced without any increase in charges for interest, office work, 
and other overhead expenses. When this bonus system was first 
introduced, it produced only a slight effect. The girls did not 
seem to care about the bonuses and made little effort to get 
them. Then the management realized that the parents were get- 
ting the extra money, and so it made no difference to the girls, 
most of whom gave their pay envelopes unopened to their fathers 
or mothers. Thereafter the bonus was not put in the pay envel- 
ope, but was handed out in loose change. The girls kept it and 
began to work hard. In the third factory, whose figures are not 
extensive enough to be used in Figure 1, but which enter into 
other computations, a similar system is employed. A limit is 
set for each task. If the work is performed within that time a 
bonus is paid. Otherwise the operatives receive only the regular 
pay, no matter how much time they spend. The introduction of 
this system has increased the output of the factory enormously. 
Inasmuch as the various systems of bonuses and premiums are 
equally applicable at all times of the year, it seems impossible 
to find in the factories themselves any reason why earnings 
should be very low in January, moderately low in July, high in 
June, and very high in November. 

We seem forced to search outside of the factories for the 
reasons for our seasonal fluctuations of wages. Such things as 
panics, hard times, or strikes would certainly cause a general 
change in the conditions of work, but nothing of the kind oc- 
curred during the period under consideration. Moreover, such 
events do not recur at the same time each year. Aside from the 
seasons, the only event which recurs regularly year after year 
at the same time and which is important enough to cause varia- 


tions in wages is Christmas. Its effect can be seen unmistakably 
in each of the solid year-curves. In that for 1910 it appears in 
the little hump which culminates during the next to the last 
week in December. In the other three it comes a week earlier be- 
cause this factory does not pay the week's wages on the Satur- 
day of the week in question, but a week later, after there has 
been time to check up the work and make allowances for that 
which is poorly done. Hence, money for Christmas must be 
earned before the middle of December. If there were no such 
thing as Christmas, the wages would probably drop off in the 
way shown by the dash line in the average curve of Figure 1. 
After Christmas the wages probably drop somewhat lower than 
would otherwise be the case, for there must be a reaction from 
the previous effort, but it is noticeable that the wages do not 
reach their lowest ebb directly after Christmas, but keep on 
falling for nearly a month. Something else keeps them low. The 
Christmas hump is significant chiefly because it shows unmis- 
takably that an outside stimulus which applies to all the opera- 
tives produces a distinct result. We may properly infer that 
the other permanent features of our curves are also due to some 
outside force which influences all the operatives. That force must 
be connected with the seasons, and it must be far more powerful 
than Christmas, for its effects are far greater. There seems to 
be no recourse except to ascribe the fluctuations of the curves 
to climate. 

The verity of the conclusion just reached is strongly con- 
firmed by comparison with other regions and other types of 
human activity. Figure 2, which, for convenience, is here divided 
into two overlapping portions, presents a series of curves ar- 
ranged according to climate, those from regions with cold win- 
ters and cool summers being at the top, and cool winters and hot 
summers at the bottom. The curves range from the Adirondacks 
in northern New York to Tampa in southern Florida, and in- 
clude one from Denmark. With them I have repeated some of 

Figured. Human g-S'S&^g-gsltiSS 
Activity and the ^^^feS^^^^^^O 25 








A. Gain in Weight of 
1200 Tubercular 90 
Patients at Sara- A 



nac Lake, N. Y., g5 















B. Work of 160 Fac- 




tory Operatives in 



Connecticut, 1913. 



Repeated from ** 


Figure 1. 







f \ 



C. Work of 60 Fac- % 
tory Operatives in 








Connecticut, 1911. 94 
Repeated from 
Figure 2. G 

D. Deaths in the 








State of New York, 




1892-1906. In- D 
verted. In the 
scale of this curve, 







100 represents the 

Ss ^ 

- .** 

\ j 

average death 






E. Strength of 90 110 
School Children in ^ 






Denmark, 1904-6. 


















f \ 





F. Work of 410 Fac- 





tory Operatives in 



Connecticut, 1910- p 


1913. Repeated 



from Figure 1. 















G. Work of 65 Girls at % 
Winston-Salem, N. Q 






% ^ 

C., 1914. 







,Q & c * , b *ti+ J > g Figure 2b. Human 

^feS<JJ3 ^ i < co O Q Activity and the 











F. Work of 410 Fac- 





96 tory Operatives in 





Connecticut, 1910- 


94 1913. Repeated 


from Figure i. 










G. Work of 65 Girls at 






Winston Salem, N. 






C., 1914. 









98 H. Work of 120 Opera 
lives in Cot ton Fac- 




tories at Columbia, 





96 S. C., 19 12- J 4. 








I. Work of 120 Opera 
tives in Cotton Fac- 





tories near A u- 





100 gusta, Ga., 1912-14. 




J. Work of 57 Carpen- 



ters at Jackson- 





-. - 

96 ville, Fla., 1911 14. 


^ ' 









K. Work of 400 Cipir- 


makers at Jackson- 



ville, Fla., 1911. 






1913, 1914. 














96 L. Work of 2300 Cigar- 
makers at Tampa, 


Fla.. 1912-14. 












NOTE. In Figures 2a and 2b the unit is a year's work of an individual. Thus "120 Opera- 
tives, 1912-14," means an average of 40 per year for three years. 


the curves of Figure 1 for the sake of comparison. The most 
remarkable feature of this series is that, although there is great 
diversity of place and of activity, all the curves harmonize with 
what would be expected on the basis of Figure 1. 

The first curve, A, is based on the work of Lawrason Brown, 
a physician who has published records of the weight gained by 
patients suffering from pulmonary tuberculosis at a sanatorium 
at Saranac Lake in the Adirondacks. A gain in weight in this 
disease is a favorable symptom, for one of the most marked 
effects of tuberculosis is to cause a wasting away of the flesh. 
In the present tabulation the patients who lost weight are not 
included, and a drop in the curve does not indicate loss of 
weight but merely a decreased rate of gain. If the patients who 
lost weight were also included, however, the form of the curve 
would still be the same, according to Brown. The Adirondacks, 
as everyone knows, have long cold winters, while the summers 
are delightfully bracing, being warm enough to be pleasant, but 
never hot enough to be debilitating. Hence, from about the first 
of April to the end of September the sick people make a marked 
gain. During the other six months, although they may gain more 
than would be the case in their own homes, they do not find the 
climate nearly so advantageous as in summer, and the disad- 
vantage increases until the snow disappears. The next curve, B, 
is a repetition of the Connecticut curve for 1913. That year the 
winter was by no means so severe as is ordinarily the case in 
the Adirondacks. Hence, the curve does not remain low quite so 
long as does A, and does not begin to fall so soon. The summer, 
however, was almost as cool as among the Adirondacks, and 
hence there is no drop during July. 

The next pair of curves represents a year with a hot summer 
in Connecticut, C, and the death rate for fifteen years in the 
state of New York, D. The curve for deaths has been turned 
upside down, so that high places represent few deaths, that is, 
high vitality corresponding to high energy in the factory opera- 


lives. In New York State as a whole the effect of the summers 
is very different from what it is in the Adirondacks. The cities 
swelter for a few weeks in July, and that sends the death rate 
up enormously, especially among children, who are quickly 
taken sick, and who either die after a few days' illness, or re- 
cover. That is why the curve drops so sharply in mid-summer. 
In the winter, on the contrary, although it drops almost equally 
low, the maximum number of deaths per day does not come till 
March, although by that time the average energy of operatives 
lias risen considerably. This is because people become sick in 
January and February, especially those who are elderly, and 
finally die after lingering illnesses quite unlike those of children. 
The death rate of other places might be used quite as well as 
that of New York. The Japanese rate, for instance, is as fol- 
lows, the figures being those for the ten years beginning with 
1899. The figures represent percentages of the normal. Those 
for the state of New York, computed on the same basis, are added 
in parentheses : 

January, 104 (105) 

February, 108 (108) 

March, 103 (109) 

April, 90 (106) 

May, 85 (100) 

June, 84 (90) 

July, 97(110) 

August, 116 (104) 

September, 118 (97) 

October, 102 (89) 

November, 96 (86) 

December, 98 (93) 

Here the course of events is almost the same as in New York, 
but with significant differences which harmonize with the cli- 
mates of the two places. Winter in Japan is less severe than in 
New York, and its effects do not last so long, for the highest 
mortality is in February instead of March. The Japanese sum- 
mers, on the contrary, are characterized by prolonged heat, and 
also by great humidity, especially during the rainy season from 
July to September. At the end of this period the mortality is at 
a maximum. The debilitating effect of the summer lasts so long 
that November and December have a higher death rate than 
May and June. The late spring is especially favorable, not only 


because of its own excellent character, but because it follows a 
winter which is not severe enough to be highly disadvantageous. 

Curves E and F represent the strength of ninety school chil- 
dren in Copenhagen as measured by Lehmann and Pedersen, and 
the average energy of factory operatives for four years in Con- 
necticut. The Danish measurements were carried on during the 
school years of 1904-1905 when sixty children were tested 
weekly, and 1905-1906 when ten were tested daily. By com- 
bining the two years into one and making allowance for the fact 
that children grow stronger from month to month just as 
factory operatives grow more skillful, we obtain curve E in 
Figure 2. Since neither summer nor winter is especially severe in 
Denmark the dip at the two seasons is the same. The maxima in 
June and November are almost synchronous with those in Con- 
necticut. The minima are both delayed six or seven weeks, but 
the winter minimum in March agrees with the maximum death 
rate in New York. The summer minimum ought possibly to come 
in July or August, but the figures for those months are not ob- 
tainable, for during that time the schools in Copenhagen have 
vacation. In addition to this we should expect the Danish curve 
to lag a little behind that of Connecticut because of the maritime 
climate. Inasmuch as Denmark is constantly swept by west winds 
from the ocean it does not so quickly grow cool in winter nor 
warm in summer as does Connecticut, where the prevailing winds 
are from the continental interior, which of course becomes 
rapidly warm in summer and cool in winter. Thus it appears that 
the strength of Danish children and the energy of factory opera- 
tives in Connecticut have an almost identical relation to sea- 
sonal variations of climate. 

Judging by curves C to F in Figure 2 one might hazard the 
hypothesis that man is subject to a seasonal rhythm which re- 
peats itself wherever he goes without regard to the climate. On 
this basis one would expect maxima of efficiency in June and 
November in all parts of the world. In curves A and B, however, 


we have already seen that where the summers are particularly 
favorable and the winters unfavorable this rhythm breaks down, 
and the June maximum and summer minimum disappear. If we 
go farther south to places where the winters are favorable and 
the summers very hot, we find a change in the opposite direction, 
for the winter minimum tends to disappear, and the summer 
minimum greatly increases and shoves the two maxima more and 
more into the winter until the two coalesce. This is evident in 
curves G to L. These represent variations in the wages of piece- 
workers in southern factories, compiled according to the method 
used in Connecticut. Curve G shows the work of sixty-five Anglo- 
Saxon girls in a tobacco factory in Winston-Salem, North Caro- 
lina. They were pasting labels on cans. Notice how their winter 
minimum comes in early May instead of June. In September the 
curve drops suddenly. This is because at that time the effect of 
the war began to be felt, the price of cotton fell so low that the 
South was in great distress, and the sale of the goods made by 
this factory began to be curtailed. Therefore the girls were not 
given as much work as they could do. 

Curves H and I are from cotton mills in South Carolina and 
Georgia, and each represents two mills. In South Carolina the 
two mills are close together at Columbia, while in the other case 
they are fifteen or twenty miles apart, one being in Georgia 
near Augusta, and the other across the Savannah River in South 
Carolina. The operatives in all cases are of pure Anglo-Saxon 
stock, chiefly of the "poor white" class. Men and women are 
included in nearly equal numbers. Part are weavers, while others, 
engaged in the occupations known as slubbing, spooling, and 
speeding, tend machines which spin the thread and wind it on 
bobbins ready for the weavers. In all cotton factories the air 
in the weaving room, and to a less extent in the others, is kept at 
a high temperature and a high humidity. This is necessary be- 
cause when the air becomes cool, or especially when it becomes 
dry, the thread is apt to break and cause blemishes in the cloth. 


Hence, in factories where high-grade goods are manufactured 
the inside temperature is so abnormal and the amount of goods 
produced depends so largely on the breakage that it is almost 
impossible to obtain satisfactory figures. In the factories here 
considered, however, nothing but coarse cloth is manufactured. 
The breaking of the thread does little harm, and relatively slight 
attention is paid to the temperature and humidity of the weav- 
ing rooms. Moreover, for slubbing, speeding, and spooling, the 
temperature and humidity make far less difference than for 
weaving. Hence, the variations in the amount of goods produced 
per person depend largely on the energy of the operatives in 
watching their machines and preventing them from standing 
idle because of broken threads, empty bobbins, or other acci- 
dents. The exigencies of business, that is, the demands for goods, 
make no difference to the operatives so far as their production 
per hour is concerned, for the machines run at a uniform speed 
whether the factory runs one day a week or six. The cotton mill 
curves arc essentially the same as that of the tobacco factory. 
In H there is a double spring maximum, due to accidental cir- 
cumstances, but the true maximum would probably come about 
the end of April. In I the spring maximum comes still earlier, 
that is in mid-April, as is appropriate to a place so far south. 
The autumn maxima, on the other hand, come later than in 
Connecticut, one being in early December and the other toward 
the end of November. 

The work of carpenters in Jacksonville, as shown in curve J, 
is different from anything else that is here considered because it 
is performed out of doors. The fifteen men per year whose 
records are here used were engaged in making the same kind of 
repairs time after time. A careful record of the hours that they 
spend is kept, but the number varies greatly on account of the 
weather. If it rains they cannot work. Summer is the rainiest 
period, but that does not tend to diminish the amount of work 
done per hour. In fact it increases it. The rain comes in hard 


showers, and while it is falling the men rarely try to work, and 
the time is not reckoned. When the rain is over they work better 
than before because the air is cooler, although still far from 
being cool. In winter, on the contrary, from December to March, 
the rain is a pronounced hindrance. It often comes in the form 
of a drizzle, and the carpenters try to keep on working while it 
is falling. Moreover, after the rain the wood is wet, there is apt 
to be a chilly wind, the hands feel numb, and everything is op- 
posed to great efficiency. Yet in spite of this, more work per hour 
is done in February, the worst winter month, than in May, June, 
July, or August. If these men were at work in well-protected 
sheds which were heated on the occasional cool days, there is 
little doubt that in December their curve would reach a maxi- 
mum higher than that now reached in November, while even if 
the following months were not still better, they would at least 
show no pronounced drop. 

The lower two curves, K and L, represent the work of cigar- 
makers at Jacksonville in northern Florida and Tampa in the 
southern part of the state. Those in Jacksonville were mostly 
Cubans, nearly two thirds being negroes, and the rest of Span- 
ish descent. At Tampa only a handful of negroes is included, 
but a large sprinkling of real Spaniards is found among the 
Spanish Cubans. The curves for the cigar factories are com- 
piled on a different basis from the others. The reason is that 
there are no definite hours. The factories are open twelve hours 
a day, usually from 6 a.m. to 6 p.m. The operatives saunter in 
as they please, provided they do not come later than 8 a.m., and 
leave when they choose, although an attempt is made to let no 
one depart before 4 p.m. While at work they sit close together 
at tables, and talk volubly except when a hired reader is vocifer- 
ating the news from a Spanish newspaper. At some time in the 
morning they go out for a lunch, but are rarely gone as much as 
half an hour. Otherwise they stay at their work till it is finished. 

Since there are no fixed hours, we cannot measure the exact 


earnings per hour, as we have done in other cases, but only the 
earnings in proportion to the time that a man might have 
worked if he had chosen to do so. In other words, we measure 
partly the actual capacity for work, and partly the inclination 
to work. In general the two seem to vary together, but the work 
of the New York State Commission on School Ventilation has 
shown that during short periods of high temperature the ca- 
pacity may remain unimpaired, while the inclination declines. 
In the practical work of life a lack of inclination is almost worse 
than a lack of capacity. 

During the warmer half of the year the possible working time 
in the Florida cigar factories may be properly reckoned as 
eleven and a half hours. In winter, however, the light at morn- 
ing and evening is not adequate for the somewhat exacting work 
of cigar-making. Therefore the men are not allowed to begin so 
early as in summer, nor to work so late. The exact time depends 
on the degree of cloudiness as well as the height of the sun. The 
factory managers say that in December the working time is cur- 
tailed an hour and a quarter or more for the month as a whole. 
In order not to make the winter production appear unduly large, 
I have reckoned that during the shortest week -not month 


the working time is an hour and nine minutes, that is, 10 per 
cent less than in summer. Before and after that date it steadily 
increases to the solstices, when it reaches the normal. Thus we 
get the lower curve for Tampa. It drops low in summer and 
rises to a single maximum in winter. At Jacksonville the varia- 
tions in the length of the working day on account of light are 
less than at Tampa because a lower grade of cigars is made, and 
hence the men are allowed to work under less favorable condi- 
tions of light. Inasmuch as the exact effort of dark mornings 
and evenings cannot be determined, I have drawn two lines at 
each end of the curve. The lower shows the wages if no allow- 
ance is made for light, and the upper if the full Tampa allow- 
ance is made. The actual truth lies between the two. For our 


present purpose this uncertainty makes no difference, since in 
either case we have the summer minimum and winter maximum 
which all our other studies would lead us to expect in this lati- 

The exigencies of business have more effect on the work of the 
cigar-makers than on that of the other operatives employed in 
Figure 2, but they do not determine the main fluctuations of the 
curves here used. In some cigar factories, to be sure, if business 
is slack the employees are often not allowed to make more than 
half or two thirds the usual number of cigars. For this reason I 
have omitted two factories whose figures I worked up, but whose 
curves I finally found to be almost wholly controlled by the 
supply and demand of the business. In the three factories which 
were finally used, however, that is, one at Jacksonville and two 
at Tampa, the operatives are only rarely placed on a limit. It 
is too expensive, especially where high-priced cigars are made, 
for four cigars a day have to be allowed to each man for 
"smokes." Each man smokes his full number, if not more, no 
matter whether he makes one hundred cigars or two hundred. 
The rush season for cigars begins in June or July and becomes 
increasingly intense until about the middle of November, by 
which time most of the Christmas orders have been received. 
Business is dullest in January and February. The operatives, 
however, know nothing about this, except as they see that men 
are taken on or discharged. The frequency of changes in the 
number of employees makes the cigar-maker's life hard, and 
accounts for much of his proverbial shiftlessness. 

Another thing which affects the wages of cigar-makers is the 
dampness of the air. During the warm, damp days so character- 
istic of the Florida summer, the tobacco is very pliable and 
easily worked, while on dry, winter days its brittleness causes it 
to break so that the work is hampered. If it were not for this 
the difference between summer and winter would be intensified. 

The most striking proof of the effect of the seasons is yet to 


be recorded. It consists of a series of data corresponding to those 
of the Connecticut factories, but based on the work of operatives 
in a large factory engaged in making electrical apparatus at 
Pittsburgh, Pennsylvania. The employees whose wages were 
investigated were employed in winding wire coils, assembling 
the parts of motors, and other similar operations which demand 
accuracy and speed. The admirable way in which the records of 
this company are kept renders the figures of great value, but 
lack of time and funds has made it necessary to limit the present 
investigation to monthly, or, in 1912, bi-weekly averages of 
hourly earnings. For this reason the resulting curves, which 
have been inserted as fine dotted lines in Figure 1 (page 59), are 
smoother than those of Connecticut where the daily earnings 
have been utilized. The number of piece-workers on which these 
Pittsburgh curves are based is shown in the following table: 

1910. Approximately 950 men and girls in winding section. 

1911. Approximately 750 men and girls in winding section. 

1912. Twenty-seven girls, winders; 42 men, tinners, black- 
smiths, painters. In this case all the operatives were especially 
steady hands who worked throughout the year. In the few cases 
where they were absent, interpolation has been resorted to. 
Hence this year's curve is more reliable than the others which 
are based on all the operatives in a given section or in the whole 
factory without regard to whether they worked steadily. 

1913. Approximately 7000 men and girls in the entire fac- 

The general form of the curves for Pittsburgh and Connec- 
ticut is obviously the same. In 1910 notice the deep dip in Janu- 
ary, and the moderate drop in summer. The next year, 1911, 
presents quite a different aspect. Because of the hot summer, 
the depressions in January and July are almost equally deep, 
the difference between the highest and lowest points is less than 


in most years, and the autumn maximum does not rise high above 
that of May or June, as is usually the case. The curves for 1912 
both show a deep depression in winter which lasts unusually 
long. During the summer, on the contrary, there is not so great 
a decrease in efficiency as during the previous two years. Finally, 
in 1913, both curves rise almost steadily from midwinter to late 
fall, with only a slight drop in summer. 

The agreement between the curves for Connecticut and Penn- 
sylvania is far too close to be accidental. At Pittsburgh, just 
as at the other factories, variations in the total number of em- 
ployees form an accurate measure of the demand for work, but 
these by no means vary in harmony with the actual production 
per operative. Often the average amount of work done by a 
given group of individuals, or by all the piece-workers, declines 
when the number of operatives increases, but quite as often the 
reverse is true. Hence the conditions under which the factories 
are run do not explain the variations in wages. Moreover, it 
stands to reason that the same irregular variations would not 
occur season after season in an electric factory in Pittsburgh 
and in brass and hinge factories in Connecticut 400 miles away 
unless all were under the same control. The only common con- 
trolling factor which varies in harmony with the curves of 
Figure 1 is the general character of the seasons. This is essen- 
tially the same in both places. 

We have now seen that from New England to Florida physi- 
cal strength and health vary in accordance with the seasons. 
Extremes seem to produce the same effect everywhere. The next 
question is whether mental activity varies in the same way. Leh- 
mann and Peclersen made a series of tests of the ability of school 
children in addition. Their general conclusion is that mental 
work varies in the same way as physical, but reaches its highest 
efficiency at a lower temperature. This agrees with the investi- 
gations of a few other scientists, and with the general conclu- 
sions of the world as summed up in the old adage, "No one is 


worth a tinker's dam on whom the snow does not fall." Before 
we can accept this, however, tests are needed on a large scale. 
The most feasible method at present seems to be by means of the 
marks of students in such schools as West Point and Annapolis. 
There the young men live an extremely regular life with a mini- 
mum of outside distractions. Their recitations are graded with 
great severity and regularity, and a given subject is often 
taught six days in the week. The marks are handed to the heads 
of departments at frequent intervals and are posted where the 
students can see them. No class is taught in divisions of more 
more than ten or twelve, so that every student has a full oppor- 
tunity to show how well he is prepared. In order to avoid all 
chance of favoritism the instructors do not keep the same divi- 
sion month after month, but change every few weeks. Altogether 
it would be hard to devise a system which more thoroughly 
eliminates the human and accidental factors. As an instructor at 
West Point put it: "We are not really teachers. We are just 
put here as officers to see whether the cadets have studied their 
books, and to decide how many marks to take off." This is pre- 
eminently true in mathematics, where the solution of a problem 
is either right or wrong and can be marked accordingly. 

When I broached my plan to the superintendents at the two 
academies, it was received with much interest, and every facility 
was placed at my disposal. I take this opportunity to express 
my warm appreciation of their courtesy. Some of the instructors 
were commissioned to see that the proper records were available. 
The marks of individuals were, of course, not necessary. The 
various marks for each day or week were merely added, and 
averaged. The data here employed embrace the following: (1) 
The weekly averages in mathematics for the first-year or enter- 
ing class at Annapolis for the six academic years beginning with 
1907-1908 and ending with 1912-1913. These classes recite six 
times a week. (2) The daily marks for the first-year class in 
English at Annapolis for the year 1912-1913. This class recites 



four times a week. (3) The daily marks in mathematics for a 
year and a half for the classes entering West Point in 1909 and 
1910. Recitations are held six days a week. The classes at 
Annapolis average about 220 in number and those at West Point 
about 120. The entire number of students whose marks have 
been used is between seventeen and eighteen hundred, but as 
some of the marks cover a period of a year and a half, the total 
is equivalent to about nineteen hundred students for a single 

All these marks have been combined into the three lower 
curves of Figure 8. Before discussing them a few words should 

Oct Nov. Dec, Jan Feb. Mar flpr. Hay June 

470 Operative* 

Z40 Student* in 
Mathematics at 
West Point 

22O Students in 
English at 

Mathematics at 

Figure 3. Seasonal Variations of Mental Compared with 
Physical Activity 


be said as to the method of preparation. The systems of mark- 
ing at the two academies are quite different. At Annapolis the 
department of mathematics tries to keep the average as nearly 
uniform as possible. If the instructors discover that the average 
is rising or falling they mark more severely or leniently to 
counteract it. At West Point, on the other hand, the marks 
regularly begin high at the opening of the term and fall steadily 
toward the end. There is no attempt to keep them at a uniform 
level, but the instructors merely mark harder and harder or 
give more and more work as time goes on. Both systems tend 
to mask the effect of the seasons. The influence of the deliberate 
attempt to keep the marks at a uniform level at Annapolis is 
largely overcome by using a series of six years. The irregulari- 
ties of one year counteract those of another except where special 
circumstances such as vacations interpose a disturbing element 
at the same time each year. In the English department at Annap- 
olis there is less stringency about keeping the marks at a uni- 
form level, and those of a single year show clearly the normal 
seasonal trend. At the end of the year, however, I have omitted 
the two weeks before examinations because there was then a 
sudden spurt accompanied by abnormally high marks. Other- 
wise all the Annapolis marks without exception have been em- 
ployed in computing the curves of Figure 3. 

At West Point it has been necessary to eliminate the effect of 
the steady fall. The method is the same as in the correction for 
increasing practice. In order to eliminate the effect of such 
things as football games, holidays, examinations, reprimands, 
or other circumstances which clearly have nothing to do with 
climate, I have omitted all the days whose marks fall more than 
10 per cent above or below what would be expected at that par- 
ticular date. Omissions of this sort are such a common procedure 
in astronomical and physical measurements that the mathema- 
tician requires nothing more than a mere mention of what has 
been done. To the layman it may seem that they are of great 


importance. In reality they rarely alter the general form of the 
final curves, for exceptionally high figures balance exceptionally 
low. In the second curve of Figure 3 the effect is slight except 
upon the first weeks in January. There the minor maximum 
which occurs just after the Christmas recess is only about half 
as large as it would be if no data were omitted. At Annapolis it 
is not necessary to omit the days of special events because the 
marks are not subject to such wide fluctuations. It is interesting 
to notice that the classes in mathematics there are influenced 
by the vacation, which comes at the end of January, just as at 
West Point. The English marks, on the contrary, are uninflu- 
enced, probably because English is an easier subject than 
mathematics. Moreover, as it is taught fewer days per week, 
and hence has less weight in determining the final marks for the 
work of the whole year, the students do not devote so much 
energy to it. 

By this time the reader has doubtless interpreted Figure 3 
for himself. The upper line is the standard average curve for 
factory operatives in Connecticut. It is the same as the average 
curve of Figure 1, except that it begins in September instead of 
January. It is placed here to permit a comparison of the physi- 
cal work with mental. The curves of mental activity all resemble 
it in having two main maxima, in fall and spring. At West Point, 
where the climate is essentially the same as in Connecticut, the 
mental maximum in the fall comes about ten days later than the 
factory maximum, while the spring maximum comes two and a 
half months earlier. Both occur when the mean temperature is 
a little above 40 F. At Annapolis the maxima are, as it were, 
pressed toward the winter. The fall maximum in English, to be 
sure, begins early in November, but lasts till the middle of De- 
cember. Since it represents the work of only a single year, it is 
less important than the curve of mathematics, whose fall maxi- 
mum does not come till the first half of December. The spring 
maxima of both curves come in the middle of March. At Annap- 


oils, just as at West Point, the time of best work is when the 
mean temperature is not far from forty degrees. 

Summing up the matter, we find that the results of investiga- 
tions in Denmark, Japan, Connecticut, Pennsylvania, New 
York, Maryland, the Carolinas, Georgia, and Florida are in 
harmony. They all show that except in Florida neither the 
winter nor the summer is the most favorable season. Both physi- 
cal and mental activity reach pronounced maxima in the spring 
and fall, with minima in midwinter and midsummer. The con- 
sistency of our results is of great importance. It leads to the 
belief that in all parts of the world the climate is exercising an 
influence which can readily be measured, and can be subjected to 
statistical analysis. It justifies us in going on with confidence 
to ascertain exactly what effect is produced by each of the 
climatic elements, such as temperature, humidity, and pressure. 


HAVING seen that both physical and mental energy vary 
from season to season according to well-defined laws, let 
us now investigate the special features of seasonal change which 
are most effective. Temperature is far the most important, but 
before considering it, let us discuss those of minor importance. 
One of these is light. Many students have ascribed great influ- 
ence to sunlight, and to its variations from season to season, or 
from one part of the world to another. For example, C. W. 
Woodruff, an army surgeon, has written an interesting book 
on The Effect of Tropical Light on White Men. Its main thesis 
is that the backwardness of tropical countries is due to excessive 
sunlight. The actinic rays at the blue end of the spectrum, 
especially those beyond the limits of vision, possess great chemi- 
cal power, as is evident from the fact that by their aid photo- 
graphs can be taken even when no light is visible to the naked 
eye. Such rays, when they fall upon the human body, are thought 
to stimulate the cells to greater activity. At first this is bene- 
ficial : if it goes to excess the cells apparently break down. The 
process is analogous to the ripening of fruit. A moderate change 
in the green tissues produces the highly favorable condition of 
ripeness: more brings on decay. Thus while the return of the 
light after the winter of the temperate zone may be beneficial, 
excessive light may be highly injurious. 

So far as our factory operatives are concerned, no effect of 
light is to be discerned in the South, while in Connecticut it is 
at best only slight. The heavy line next to the bottom in Figure 


1 (page 34) shows that from mid-September to the middle of 
November the amount of work increases, although the days are 
growing shorter. This is exactly opposite to what would be 
expected if the shortness of the days were of primary impor- 
tance. Moreover, in June when the days are longest we find a 
sudden drop. If the length of the days had much to do with the 
matter, there is no reason why more work should be done in 
November than in June. Nor should we find that a shortening 
of the days during September is accompanied by the same kind 
of increase in efficiency which is seen in March when the days, 
although of the same length as in September, are growing longer 
instead of shorter. For all these reasons we assign only slight 
importance to variations in the amount of light. Nevertheless, 
some effect can apparently be detected. Compare the two lower 
curves of Figure 1. In spite of the low efficiency occasioned by 
the winter's cold, the curve of work begins to rise sooner than 
does the curve of temperature which is placed below it. The first 
appreciable lengthening of the days in January may cause this 
by its cheering and stimulating influence. 

The line of reasoning applied to light applies also to the pos- 
sibility that the variations of the curve of work depend on the 
extent to which people are shut up in the house. Obviously, this 
has nothing to do with the two maxima in November and May, 
nor with the minimum in July. In November people's houses 
have been shut up for a month, more or less, while in May and 
July they are wide open, or at least as wide open as they ever 
are. The extremely low minimum in January, however, is prob- 
ably due at least in part to the necessity of shutting up the house 
in winter. In October the weather becomes so cold that people 
begin to shut up their houses ; they live in stuffy, unventilated 
quarters, and fail to take exercise in the open air. By the middle 
of November this has had time to produce an effect which natu- 
rally becomes more and more marked as the weeks go on. This 
would harmonize with the decline of energy from November to 


the middle of January. In January, however, the decline ought 
not to cease if it is due chiefly to confinement within the house. 
It ought to continue until about the middle of March, for not 
till that time do people in Connecticut begin to let in the outside 
air, and not even then to any great degree. As the curve of work 
has risen distinctly by that time, some other factor must inter- 
vene, presumably the increase of light to a slight extent, and the 
rise of the temperature to a larger extent. 

A third factor to be considered at this point is the relative 
humidity of the atmosphere. A sharp distinction must be drawn 
between the humidity of the outside air and that which prevails 
within doors. Physicians, students of factory management, 
school superintendents, and many other people have repeatedly 
discussed the supposed harmful effects of the dry air in our 
buildings during the winter. A much more fully attested fact is 
the harmful influence of great humidity during hot weather. 
We are more conscious of this than of the harm arising from 
excessive dryness. This does not necessarily mean that the total 
effect is worse than that of dryness, however, for hot, humid days 
are much rarer than the winter days when the air in our houses 
is drier than that of the majority of deserts. 

So far as our curves of work are concerned, humidity does not 
seem to be responsible for the fluctuations except as it is influ- 
enced by temperature. In other words, the average humidity of 
the outside air from season to season does not vary in such a way 
as to cause maxima in May and November, and minima in Janu- 
ary and July. The average humidity of the outside air in No- 
vember and in January is not greatly different. Nevertheless, the 
inside humidity is probably an important factor in causing the 
low efficiency of midwinter. 

The relation of work and humidity among the factory opera- 
tives of Connecticut is illustrated in Figure 4. There the year 
has been divided in three parts: (1) winter, (2) spring and 
autumn, and (3) summer. In each part all the days having a 



given humidity have been averaged together, and the smoothed 
results have been plotted. The heavy, solid lines represent what 
I believe to be the true conditions when other disturbing elements 
are removed, while the dotted lines show the actual figures. In 
winter the dampest days are unmistakably the times of greatest 
efficiency. We may shiver when the air is raw, but we work well. 

50 55 60 65 70 75 80 85 90 95 100% Rel. Hum. 











Figure 4. Relative Humidity and Work in Connecticut 

a. Winter. b. Spring and Fall. c. Summer. 

This is partly because in winter the dampest third of the De- 
cembers, Januaries, etc., averages nearly 2 F. warmer than the 
driest third. Moreover, moist air at any given temperature feels 
warmer than dry and hence is less likely to cause people to 
overheat their houses. 

In the spring and fall, when the temperature ranges from 
freezing to 70, with an average of about 50 F., the best work is 
performed with a relative humidity of about 75 per cent. In 
other words, neither the dry nor the wet days are the best. The 


summer curve is the most complex of the three. It rises first to 
a maximum at 60 or 65 per cent, then falls, and once more rises 
to a higher maximum. The first maximum seems to be due to 
humidity, the second to temperature. A hot, damp day is un- 
questionably debilitating. The majority of the dampest days 
in summer, however, are comparatively cool, for they accom- 
pany storms. The coolness counterbalances the humidity, and 
people's efficiency increases. Hence, we disregard the right-hand 
maximum and conclude that with an average temperature of 65 
to 70 a relative humidity of about 60 per cent is desirable. 

The most unmistakable feature of the curves as a whole is 
that they show a diminution of work in very dry weather. This 
presumably has a bearing on the low level of the curve of energy 
in winter. At that season the air in our houses ought to have a 
humidity of 60 or 65 per cent, but most of the time the figure 
is only 20 or 30. On very cold days the percentage is still lower. 
For instance, if the outside air has a temperature of 14 F. 
( 10 C.) and contains all the moisture it can hold, which is 
usually not the case, its relative humidity when it is warmed to 
70 F. will be only 12 per cent. Even on days when the outside 
humidity rises to 100 per cent and the temperature is 40, the 
air in an ordinary steam-heated house has a relative humidity 
of only 85 per cent, which is far below the optimum. Apparently, 
this extreme aridity is debilitating. It probably dries up the 
mucous membranes in such a way as to increase our suscepti- 
bility to colds. In this way it may be an important factor in 
causing February and March to have the highest death rate of 
the year. There has been a good deal of discussion as to the 
actual importance of atmospheric humidity, and no small 
amount of disagreement. We shall return to the matter later 
when we study health. 

While the effects of light, of closed houses, and of excessive 
dryness explain part of the fluctuations of the curve of work, 
they have little bearing on any season except the winter. An- 


other matter which may be suggested in this connection is vaca- 
tions. These, like many other conditions of human life, are 
largely seasonal. Do people work fast in the fall because they 
have been rested by vacations? In professional occupations and 
in business this certainly seems to be the case, but not among 
factory operatives. As a rule such people do not take summer 
vacations. They usually stop work at irregular intervals, or 
else after Christmas when many factories shut down or work on 
part time for a few days to prepare for the new year. The form 
of our main curve, however, shows that neither at this time nor 
in summer do vacations produce any appreciable stimulating 
results. If they were the cause of fast work, the curve ought to 
be the highest within a few weeks after the people return to work, 
but this is not the case. During the vacation period of July and 
August the amount of work is moderately low, and in early 
January, after the Christmas break, very low. At the end of 
August it begins to increase, and increases steadily for two and 
a half months. The maximum in November is so long after the 
vacation period that it can hardly have anything to do with it. 
What has just been said has an important practical appli- 
cation. There is a common idea that people need vacations in 
summer. Of course there are strong arguments for this, since 
pleasant recreation is then possible out of doors. Nevertheless, 
the need is apparently greater in winter than in summer. To 
meet this it is probably wise that work should be light during 
the winter. Already, as everyone knows, many factories run on 
part time during the first few weeks of the year, and now we see 
that there are strong physical reasons for this. Another impor- 
tant suggestion afforded by our curves is this : If the operatives 
of a factory, or people engaged in any other kind of work, are 
to be speeded up, the time to do it is when nature lends her aid. 
To speed up at the end of January is analogous to taking a 
tired horse and expecting him to win a race. Later in the year, 
however, during the spring, especially in May, people may ap- 


parently be pushed to the limit, and will not suffer, because their 
energies are naturally increasing. This is still more the case in 
October and early November. After the middle of November 
pressure may produce important results, as we see at Christmas. 
Nevertheless, the chances are that if continued it will produce 
undue exhaustion, followed by a serious reaction. Possibly the 
nervousness of Americans is due partly to the fact that although 
we relax somewhat in summer, we keep ourselves at high pressure 
through the winter when the need of relaxation is greatest. 

Turning now to temperature, we see that in Figure 1 (page 
84) the lower curve, showing the march of temperature through 
the year, and the Connecticut curve just above it are similar in 
many ways. Both are low in midwinter. From February onward 
they rise together until about the middle of June. Then the effi- 
ciency curve falls while the other goes on rising, a condition 
which fully accords with ordinary experience. The fall of the 
efficiency curve begins when the average temperature has risen 
to about 68. When the temperature stops rising, the work stops 
falling, and then remains nearly steady through July. At the 
end of July the mean temperature has fallen to about 71. Dur- 
ing the succeeding period of favorable temperature the two 
curves disagree, for the amount of work goes up while the tem- 
perature falls. When the average temperature falls below 48, 
however, and begins apparently to be unfavorable to physical 
exertion, the curve of work turns downward. Thereafter, if we 
omit the Christmas hump and use the dotted line, the tempera- 
ture and the amount of work decline together until they reach 
the lowest point in January. It is worth while once more to call 
attention to the somewhat surprising fact that in southern New 
England, contrary to our ordinary opinion, low temperature 
seems to be much more injurious than high. 

This by no means indicates that high temperature is favor- 
able. Let us consider the effect of the high temperatures of the 
four successive summers shown in Figure 1 (page 84). Compare 

x/fJvy&Jvty August Sept 

Figure 5. Average Weekly Temperature During the 
Summers of 1910-13 in Connecticut 


the summer dip in the Connecticut curve, that is, the area below 
the horizontal lines, with the heavily shaded areas of Figure 5, 
which shows the average temperature each week during the four 
summers from 1910 to 1913. The black portions indicate weeks 
having an average temperature night and day of over 73. The 
size and distribution of these periods of extreme heat are in close 
correspondence with the amounts by which the curves of Figure 
1 drop below the horizontal lines during the summers. This is 
illustrated in the following little table. The line marked "defi- 
ciency in work" indicates the amount by which the efficiency of 
the operatives diminished because of the hot weather, that is, 
the area below the horizontal lines of Figure 1. The year when 
the diminution was greatest is reckoned as 100 and the others 
in corresponding ratios. The other numbers show the area of 
the heavy black shading in Figure 5 and represent the intensity 
and duration of the hot weather. Here, too, the year of maxi- 
mum heat is represented by 100, and the others by proportional 

YEAR. 1910 1911 1912 1913 

Deficiency in work, 58 100 8 2 

Severity of heat, 52 100 50 34 

In each case 1911 stands highest, 1910 next, and then 1912 
and 1913. In 1911 the heat not only was extreme, but lasted 
long, three weeks at one time and two at another. The death rate 
for July, 1911, in Massachusetts was 50 per cent greater than 
in the preceding June. In 1910 the hot weather was not so severe, 
it lasted four weeks instead of five, and was divided into three 
parts instead of two. In 1912 the number of hot weeks was the 
same as in 1910. One was extremely hot, but the rest were not 
bad. Moreover, they did not come together, and the last was 
separated from the others by three cool weeks during which 
people had time to recover, which was not the case in 1910. 


Finally, 1913 was a very mild year with only two extreme weeks 
which were separated by three moderate weeks. 

An examination of Figure 5 makes it clear that only the ex- 
treme weeks are harmful. Thus 1911 was a truly terrible summer 
and 1913 a delightful one. Yet during 1911 the temperature 
remained above 69 for only eight weeks while in 1913 it re- 
mained above that figure for twelve weeks. Thus it appears that 
if the average temperature does not rise above about 70, and 
if the noon temperature rarely exceeds 80, the physical capac- 
ity of European races in the United States does not suffer any 
serious diminution. A slight further rise however only four or 
five degrees produces disastrous consequences. A single week 
of such weather does no great harm, but when several weeks 
come together people rapidly become weakened. The weakening 
is greater than appears in our diagrams, for during hot spells 
many of the operatives, particularly the girls, stop work entirely 
or stay at home in the afternoon. Those who remain are the 
stronger ones, and naturally their wages are higher than the 
general average. Moreover, in 1911 the heat was so intense that 
the factory shut down for two or three days. Thus, if allowance 
is made for these facts, the difference which a few degrees make 
between two summers such as 1911 and 1913 becomes even more 
pronounced. The full effect of a hot summer, especially when it 
is very damp, may be gauged by the death rate in Japan (page 
95). September is there 18 per cent worse than the average, in- 
stead of 3 per cent better as in New York. 

The relation between the temperature and the amount of work 
in winter during the four years under discussion is not so pro- 
nounced as in summer, but can easily be detected. The hot sum- 
mer of 1911 was followed, as frequently happens, by an uncom- 
monly cold winter. The reason for both is the same. Usually hot 
weather in New England is commonly due to the movement of 
heated air from the interior toward the coast, particularly from 
the southwest to the northeast. Cold winters are due to a similar 


transportation of air from the interior, this time from the north- 
west. The interior of a continent, as is well known, cools off very 
rapidly in winter and becomes hot rapidly in summer. When 
these conditions are carried from the interior to the coasts, they 
bring to New England what climatologists call a continental 
climate instead of the more maritime climate which otherwise 

The effect of the cold winter of 1911-1912 can easily be seen 
in the curve for 1912 in Figure 1 (page 84). That year the aver- 
age temperature where the factories are located was 19.0 for 
the first five weeks compared with an average of 32.7 for the 
three other years whose curves are given. For the next five weeks 
the temperature was 24.4 compared with 35.3. The effect of 
this is seen in the low position of the 1912 curve of work far into 
the spring. The fact that the energy of the operatives remained 
low after the temperature began to rise suggests that the eifect 
of extreme conditions may last long after more normal condi- 
tions begin to prevail. The same thing is suggested by the fact 
that after the summer of 1911 the curve of work does not rise 
so high in November as in the preceding May. During each of 
the other three years the November maximum is higher than its 
predecessor. Although a single winter and a single summer are 
not enough to prove that the effect of extreme conditions does 
thus persist for many months, they suggest that a long stay in 
an adverse climate may produce results which last for years. In 
spite of a previous statement, it appears that our plan of es- 
caping from possible extreme heat by taking summer vacations 
in the mountains or at the seaside is wise. Equally wise is the 
growing habit of getting away from the severe cold for a while 
in winter. The only trouble is that those who most need such a 
change are rarely the ones who get it. If people could spend the 
summer on the Maine coast, the winter in Georgia, and the rest 
of the year in New York, they ought to be able to do the best 

Mon. Tve. 

Thvr Fri. 







98 <& 


Figure 6. Effect of the Days of the Week on Piece- Workw 

1. 60 Men, April-July, 1912. 

2. 60 Men, August-November, 1011. 
. 49 Girls, 1912. 

4. 31 Men, 1012. 

5. 14 Girls, 1912. 

6. 24 Men, 1912. 

7. 60 Men, January-March, 1910. 

8. Weighted Average of Nos. 1-7, or approximately MO People for On* Year* 


kind of work at all seasons almost without the necessity of a 

The effect of temperature ma}' be shown in more ways than 
have yet been presented. Let us determine how fast people work 
on days having various temperatures, no matter in what month 
they occur. The very cold days, of course, all come in winter, 
but may be in December, January, or February. The very hot 
days come anywhere from May to September, while days with a 
temperature of about 50 occur in almost every month of the 

The method can be illustrated by taking all the Mondays, 
all the Tuesdays, the Wednesdays, and so forth, and averaging 
the work of each day of the week. This has been done for 230 
people. The results are shown in Figure 6, which is inserted to 
show exactly how our results are obtained, and how necessary it 
is to have a large number of people. We are striving to separate 
the effects of one single condition from those of a vast number. 
We start with the wages of individuals which vary from day to 
day for hundreds of reasons wholly unconnected with the day 
of the week or the weather. The variations are so great that even 
if a man is influenced by the approach of pay-day, for example, 
we should probably not be able to detect it if we merely looked at 
his wages for a month or two. Therefore we average all the 
people of a department together, and obtain results such as 
appear in Figure 7. This shows the actual wages in percent- 
ages of the maximum which were earned by 170 people divided 
into five departments during five weeks in January and Febru- 
ary, 1913. There is little uniformity in the different lines. Where 
one goes up the other goes down. Yet closer examination shows 
that in at least four out of the five departments the wages during 
the last two weeks were a little larger than during the earlier 
weeks. The variations of the different curves are in part due 
to the persistence of individual vagaries which have not yet been 
averaged out, and in part to conditions affecting whole depart- 



ments. For example, a foreman is cross one day and good- 
natured the next ; a belt breaks and delays work ; or some of the 
operatives converse so much that their work suffers appreciably. 
If a number of departments are averaged together these acci- 


Monday Monday 

Monday Monday 

7. Variations in Daily Wages. Five Departments 
(170 people) at New Britain, Conn. 


dents, as well as those which pertain to individuals, disappear, 
but not until a great many people are considered. 

To find the effect of the days of the week, we take data such 
as are illustrated in Figure 7, select all the Mondays, Tuesdays, 
and so forth, and average each day. This gives the curves of 
Figure 6. Here we begin to detect a certain degree of uniformity, 
although the accidents and peculiarities of each department 
are still in evidence. On the whole, however, the curves are higher 
at the end of the week than at the beginning. All, to be sure, are 
irregular, and the two lower not counting the heavy line 
slope in the opposite direction to the rest. The fact that the re- 
maining five slope in the same direction shows, however, that 
these different people in different factories and during different 
years were subject to a common influence. Finally, we average 
all the departmental curves, giving each a weight proportional 
to the number of operatives. Thus we obtain the heavy lower 
line of Figure 6. This is still irregular, for although 230 people 
are included, all influences other than that of the days of the 
week are not yet eliminated. Nevertheless, the wages clearly in- 
crease toward the end of the week. If the operatives were paid by 
the day instead of by the piece, this would probably not be the 
case. They would work slowly at the end of the week by reason 
of being tired. With the piece-workers, on the contrary, other 
considerations are dominant. If they work a trifle slowly on 
Monday, they can make it up tomorrow. On Tuesday they can 
be slow and make it up on Wednesday, but a few who fell behind 
on Monday are beginning to work harder. So it goes from day 
to day until on Friday and especially Saturday many feel that 
their earnings for the week are insufficient, and hence make an 
extra effort. In some cases this may not be true, as in the curve 
next above the average curve. Yet it remains a general truth, 
and the lower curve of Figure 6 is a concrete expression of the 
fact that in the factory under discussion there is a difference 
of at least 2 per cent between Monday and Saturday. Possibly 

15 20 25 30 35 40 45 50 55 60 65 70 75 

- 4-1 

Figure 8. Human Activity and Mean Temperature 

A. 300 Men in Two Connecticut Factories, 1010-13. 

B. 196 Girls in One Connecticut Factory, 1911-13. 

C. One Man (P) in Denmark, June-December, 190(1. 

D. One Man (L) in Denmark, June- December, 1906. 

E. 880 Cigar-makers in Factory B at Tampa, Fla., 1913. 

F. 400 Cigar-makers in Factory A at Tampa, Fla., 1913. 

G. 3 Children Typewriting in New York, 1905-6. 

H. 880 Cigar-makers in Factory B at Tampa, Fla,, 1912. 

I. 1560 Students in Mathematics and English at West Point and Annapolis, 1909-191& 

NOTE. All the curves except G and 1 
every case is reckoned as 100. 

The maximum ill 


the real difference is greater, and is obscured by other circum- 
stances. In the cigar factories of Florida it rises to a far greater 
value, for the Cubans are much disinclined to work after a holi- 
day. Not only are about 10 per cent of the operatives absent on 
Mondays, but those who are present come so late or are so in- 
disposed to work that they accomplish only about 80 per cent 
as much work as on other days. This is so important a matter 
that allowance for it has been made in computations where in- 
dividual days rather than weeks are concerned. The figures for 
each day of the week for 780 men at Tampa are as follows : 
Monday, 81.9 per cent; Tuesday, 98.7 per cent; Wednesday, 
99.8 per cent; Thursday, 100 per cent; Friday, 98.3 per cent; 
and Saturday, 97.9 per cent. The other days are reckoned as of 
equal weight, but the figures for Monday have been increased 
in the ratio of 82 to 100. 

By the employment of a method similar to that used with the 
days of the week we obtain the curves shown in Figure 8. These 
are based on varying numbers of people, from one to over 700. 
Yet all show the same general character. With the exception of 
G and H, which are distinctly the least reliable, the physical 
group all reach maxima at a temperature between 59 and 65. 
Even the two less reliable curves reach their maxima within the 
next four degrees. All the curves decline at low temperatures, 
that is, on the left, and also at high. The irregularities at the 
extreme limits are largely due to the fact that there the number 
of days is so small that exact results cannot be hoped for. 

Figure 8, with the brief statements which accompany the 
respective curves, tells the whole story so plainly that it scarcely 
seems worth while to amplify it. Several points, however, may 
well be emphasized. For instance, below a certain temperature, 
which varies from curve to curve, a further reduction does not 
seem to produce much effect. People apparently become some- 
what hardened, or else the conditions within the warmed houses 
do not change much in spite of a change in the outside air. An- 


other noticeable thing is that the curve for girls has greater 
amplitude than that for men in the same region. Part of this 
is due to the inclusion of the group of Italians, already referred 
to, who are engaged in drawing hot brass and hence are benefited 
by the coldest kind of weather. Even if they were omitted, how- 
ever, the girls' curve would still vary more than that of the men. 
This seems to indicate that either because of their sex or because 
of their age, girls are more sensitive than men. 

Another point brought out by the curves is that as we go to 
more southerly climes the optimum temperature of the human 
race becomes higher. It is important to note, however, that the 
variation in the optimum is slight compared with the variation 
in the mean temperature of the places in question. For instance, 
in Connecticut the optimum seems to be about 60 for people of 
north European stock. This is about ten degrees higher than 
the mean temperature for the year as a whole. In Florida, on the 
other hand, the optimum for Cubans is about 65, which is five 
degrees lower than the mean temperature for the year at Tampa. 
In other words, with a difference of twenty degrees in the mean 
annual temperature, and with a distinctly northern race com- 
pared with a southern, we find that the optimum differs only 
about 5 F. This seems to mean that for the entire human race 
the optimum temperature probably does not vary more than 
ten or fifteen degrees. 

We have not yet pointed out all the important matters sug- 
gested by the curves of Figure 8. Above the optimum the curves 
in general begin to decline quite rapidly, but then cease to do 
so and at high temperatures are not so low as would be expected. 
This is largely because in hot weather many operatives, espe- 
cially the girls and the Cubans, do not feel like work, and so 
stay away from the factories. Those who come in spite of the 
heat are the strongest and most efficient. Naturally, their aver- 
age wages are higher than those of the ones who stay away, and 
hence the general level of our curves is too high in the portions 


based on the hottest weather. The mental curve, however, falls 
off very rapidly at high temperatures. This is because the stu- 
dents are obliged to be present on hot days just as on others. 
They must recite whether they wish or not. Hence, their curve 
is more reliable than the others. In this connection some ex- 
periments carried on by the New York State Commission on 
Ventilation are of interest. In an attempt to determine the most 
favorable conditions of ventilation the Commission placed sev- 
eral groups of persons in rooms where the temperature and hu- 
midity were under exact control, and measured their strength, 
mental activity, food consumption, and other conditions. The 
experiments lasted six or eight hours a day, and each set of 
subjects was tested for several weeks. Three temperatures were 
used, namely, 68, 75, and 85. No appreciable effect upon 
strength could be detected, nor upon mental activity, and vari- 
ous other functions. This is probably because the experiments 
were not sufficiently prolonged. That is, the subjects were in the 
experimental rooms only a third or a quarter of each day, and 
hence their condition did not have time to change appreciably. 
Although the subjects did not lose in actual strength, however, 
their inclination to work declined at high temperatures even 
within six or eight hours. 

Thus far we have been dealing with large bodies of people. It 
is peculiarly important to find that no matter how small the 
number, the same relation to temperature is discernible. One of 
the curves in Figure 8 shows the speed and accuracy of three 
children who wrote upon the typewriter a few stanzas from the 
"Faerie Queen" or a page from George Eliot daily for a year, 
and weekly for another year. Their records were kindly placed 
at my disposal by Prof. J. McK. Cattell. I have corrected them 
for the effects of practice, and have combined speed and ac- 
curacy in such a way that each has the same weight. At one 
period, for some unknown cause, the efficiency of the children 
declined greatly for two months or more. If this were eliminated 


their maximum would come at a lower temperature than now 
appears, probably not much above 60. In the curves of indi- 
viduals, we are fortunate in having careful tests made by two 
psychologists, Lehmann and Pedersen, at Copenhagen. They 
tested their own strength daily with the dynamometer, and their 
curves, copied directly from their monograph, are before us. 
One is uncommonly regular with a maximum at 64<. The other, 
less regular, has its maximum at 59. The agreement of Danish 
curves based on single individuals with New England curves 
based on hundreds is highly important. 

The last thing to be considered in Figure 8 is the mental curve 
at the bottom. It is based on so large a number of people, and 
is so regular, that its general reliability seems great, although 
I think that future studies may show the optimum to be a few 
degrees higher than is here indicated. It agrees with the results 
of Lehmann and Pedersen. Furthermore, from general observa- 
tion we are most of us aware that we are mentally more active 
in comparatively cool weather. Perhaps "spring fever" is a 
mental state far more than a physical. Apparently people do 
the best mental work on days when the thermometer ranges from 
freezing to about 50 that is, when the mean temperature is 
not far from 40. Inasmuch as human progress depends upon a 
coordination of mental and physical activity it may be that the 
greatest total efficiency occurs halfway between the mental and 
physical optima, that is, with a mean temperature of about 50. 

Curves such as those of Figure 8 are not peculiar to man 
alone. They are apparently characteristic of all types of living 
creatures. To begin with plants, many experiments have deter- 
mined the rate of growth of seedlings at various temperatures. 
The commonest method has been to grow different sets of seed- 
lings in large numbers under conditions which are identical ex- 
cept in temperature, and then to measure the average length of 
the shoots. In all cases growth is slow at low temperatures, in- 
creases gradually with higher temperatures, reaches a maximum 



like that of man, and then falls off quickly. The course of events, 
however, is not always so regular as here indicated. The curve 
of wheat, for example, as worked out by MacDougal is given in 
Figure 9. The peculiar double maximum there seen appears in 
each case where careful tests are made. It seems to be due to 
some inherent quality of the plant, and is of especial interest in 

Figure 9. Growth of Wheat at Various Temperatures 
After MacDougal 

The figures on the left indicate growth in mm. during 48 hours 

our present study because we shall soon come upon an analogous 
case in man. When many species are averaged, such irregulari- 
ties disappear, and we obtain the curve at the bottom of Figure 
10, which has been prepared by MacDougal on the basis of his 
own measurements and others given in such works as Pfeffer's 
Physiology of Plants. Many of the lower plants, such as marine 
algae, have their optima at lower temperatures than those here 
indicated, and the same is probably true of Arctic species. On 
the other hand, certain low algae which grow in hot springs must 
have their optimum at a temperature above that of ordinary 
plants. These differences are immaterial. We are now concerned 



only with the fact that so far as plants have been measured, their 
response to temperature resembles that of man. 

Apparently, we have to do with a quality which pertains to 
all kinds of living beings, and is presumably an inherent char- 
acteristic of protoplasm. The nearest approach to pure proto- 
plasm is found in unicellular organisms whose bodies show only 
the beginnings of differentiation into parts having separate 
functions. The infusoria furnish a good example. One of these, 
paramoecium, has been carefully studied by L. L. Woodruff. His 


Mental and 


Absorbhon of 
Oxyoen by 

Raie of fission 
of infusoria 


Figure 10. Mean Temperature and Vital Processes in Plants, 
Animals and Man 


original purpose was to determine whether it was possible for 
this organism to keep on reproducing itself without conjugation 
for any great length of time. Under the conditions of nature the 
small motile cells often spontaneously develop a median cell wall 
and ultimately divide into two new individuals, thus reproducing 
the species. This process, however, does not go on indefinitely, 
for when two cells come in contact they fuse with one another, 
and then begin a process of fission which, like the other process, 
ends in two individuals. Thus we have two types of reproduc- 
tion, asexual and sexual, which apparently give rise to the same 
kind of paramcecia. Woodruff's purpose was to determine 
whether asexual reproduction can persist indefinitely, or whether 
it leads in time to extinction. He has shown that if the media of 
nutrition contain a sufficient number of elements, paramcecium 
can reproduce itself indefinitely by the asexual method. Between 
May 1, 1907, and May 14, 1914, he had carried his cultures 
through 4417 generations without conjugation. In the spring of 
1924 the paramoecia were still thriving after about fourteen 
thousand asexual generations. In the course of this work he has 
found that the rate of cell-division is an accurate test of the 
conditions under which protoplasm exists. For example, when 
extracts from nephritic kidneys or certain other diseased organs 
are added to the nutrient solution, even though they are present 
in such small quantities that they cannot be detected by chemical 
analysis, they make their presence evident by a falling off in the 
rate of fission. 

One of Woodruff's most important lines of work has been to 
test the relation of his infusoria to temperature. From many 
experiments he finds that their activity corresponds closely to 
van't Hoff's law of chemical activity. According to this well- 
established law, chemical reactions of most kinds at ordinary 
temperatures become nearly three times as active with every rise 
of 10 C. Even in inorganic chemical reactions, however, and 
far more in those of the living cell, there is a distinct limit where 


this rule breaks down. This limit forms the optimum of the 
species. At higher temperatures the degree of activity declines, 
and finally death ensues. On the basis of these conclusions, 
Woodruff's data permit us to draw the second curve from the 
bottom in Figure 10. 

The next higher curve shows the amount of oxygen absorbed 
by the common crayfish at various temperatures. The most ex- 
tensive work on this subject appears to have been done by Brun- 
now. The facts here given are taken from the summary by Putter 
in his Vergleichende Physiologie. The amount of oxygen ab- 
sorbed by an animal is an excellent measure of its physical 
activity. When supplemented by measurements of the amount 
of carbon dioxide given off, and of the speed with which certain 
other metabolic or katabolic processes take place, it gives a 
true picture of the animal's general condition. Apparently, these 
various processes follow van't Hoff's law just as do the growth 
of plants and the cell-division of the infusoria. The optimum in 
the three cases does not vary greatly, that for plants being 
about 86, for paramoecium 83, and for the crayfish 74 F. 

Physiologists are not yet fully agreed as to the cause of the 
phenomena shown in these curves, although there is little doubt 
as to the general facts that they imply. One hypothesis may be 
briefly stated. According to Putter's summary, the most prob- 
able explanation is that activity goes on increasing according 
to the ordinary chemical law until it becomes so great that the 
organism is not capable of absorbing the necessary oxygen. 
That is, at a low temperature the creature easily gets what oxy- 
gen it needs, and gives it out again in the form of carbon dioxide 
or of other oxidized products which remove the waste substances 
from the body. As the temperature rises, the normal increase in 
chemical activity takes place, the animal is still able to get rid 
of all its waste products, and thus its life processes are strength- 
ened. With a further rise of temperature a change sets in. The 
chemical processes which break down the tissues of the body be- 


come still more active, but the supply of waste products to be 
eliminated by oxidation becomes so great that they cannot all 
be removed. This is because in every organism there is a distinct 
limit to the amount of oxygen which the creature can mechani- 
cally convey to different portions within a specified time. If the 
supply of oxygen is not sufficient to oxidize all the waste prod- 
ucts, some of these will remain in the system. They act as 
poisons. Their first effect is to diminish the organism's activity. 
If they accumulate to too great an extent death ensues. 

The discussion of this hypothesis must be left to the physiolo- 
gists. They must decide whether the hypothesis which explains 
the curves of cold-blooded animals and plants is also applicable 
to warm-blooded animals. There can be little doubt, however, 
that variations in the rate at which metabolism takes place in 
the human body play a part in the variations in efficiency which 
we are here studying. The researches of Thomson illustrate the 
way in which we are beginning to discover the truth. In Man- 
chester, England, from April to July, 1910, and again in March, 
1913, he measured the percentage of CO2 given off in the breath 
of four individuals under different conditions of temperature, 
humidity, and pressure. From his figures, given in the Man- 
chester Memoirs, I have compiled the following tables : 


Temperature, 50-51 52-53 54-55 56-57 58-59 60-61 62-63 64-65 98 

4<7r 4 * r2 4t66 4<T1 4i61 4<41 4<88 4 * 62 4 - 


Relative Humidity, 70-75% 76-80% 81-85% 86-90% 
Percentage of CO 2 , 4.75 4.60 4.60 4.45 


The interpretation of these tables is difficult, and I can merely 
offer a suggestion. An increase in the proportion of CO2 ex- 
haled from the lungs obviously indicates an acceleration of the 
metabolic processes which break down and consume the bodily 
tissues. This liberates energy which may manifest itself in at 
least three ways and possibly more. It may give rise to heat 
which is used to maintain the body at the normal temperature ; 
it may be used to accomplish physical or mental work; and it 
may cause an excess of heat which gives rise to further metabo- 
lism of a harmful nature. In the first part of the table the per- 
centage of C02 is comparatively high at the lowest temperature 
recorded by Thomson, and decreases with only slight irregu- 
larity till the thermometer reaches 62 F. This is close to the 
temperature which we have found to be the optimum. Below that 
point the increased metabolism is probably needed to keep the 
body warm. At higher temperatures increased production of 
CO2 is again apparent. This perhaps means that too much 
chemical activity is taking place, and that toxic substances are 
accumulating in the way suggested by Putter. At the optimum, 
according to this interpretation, the body does not have to use 
an undue portion of its strength in keeping warm, nor is it 
injured by too great stimulation. Thus it is in the best condition 
for work. 

The second part of the table shows that in the driest weather 
which England enjoys, metabolism is more active than in wet 
weather. Perhaps part of this is due to the fact that in dry 
air the body loses water and is cooled by evaporation, and hence 
requires more heat than in wet air of similar temperature. There 
is more to the matter than this, however, but further measure- 
ments are needed before an adequate explanation can be offered. 
All that can be done here is to point out the fact that in man, as 
in the lower organisms, activity varies according to tempera- 
ture. This is evident in Figure 10, where the dotted upper line 
is the curve of mental activity, while the accompanying solid 


line shows the conditions if all accidental irregularities could 
be removed. The third line in the same way represents the physi- 
cal activity of both men and women in Connecticut. I have not 
used the figures from the South because they are not quite so 
reliable as those from Connecticut. Finally, the second line from 
the top shows physical and mental activity combined, each 
being given the same weight. It may be taken as representing 
man's actual productive activity in the things that make for a 
high civilization. The resemblance of the human curves to those 
of the lower organisms is obvious. In general, the lower types of 
life, or the lower forms of activity, seem to reach their optima 
at higher temperatures than do the more advanced types and 
the more lofty functions such as mentality. The whole trend of 
biological thought is toward the conclusion that the same laws 
apply to all forms of life. They differ in application, but not in 
principle. The law of optimum temperature apparently controls 
the phenomena of life from the lowest activities of protoplasm 
to the highest activities of the human intellect. 


THE effect of a given climate depends on two primary fac- 
tors. One is the character of the seasons as expressed in 
averages such as are furnished by our weather bureaus. The 
other is the changes from day to day, that is, the weather. The 
boy quoted by Mark Twain was nearly right when he defined 
the difference between weather and climate as being that "Cli- 
mate lasts all the time and weather only a few days." Two 
climates may be almost identical in their seasonal averages, and 
yet differ enormously in their effect on life, because in one the 
change from day to day is scarcely noticeable, while in the 
other there are all sorts of rapid variations. The old Irish- 
woman who was driving her pigs to market in a pouring rain 
did not realize it, but she gave expression to a truth of the 
greatest importance, when a friend pitied her for being out in 
such weather, and she replied, "Indade it's bad, but sure it's 
thankful I am to have any kind of weather." 

The changes from one day to another depend largely upon 
our ordinary cyclonic storms. In such storms the barometer 
goes down and then up ; the wind changes in direction and ve- 
locity ; the air becomes humid, clouds gather, rain usually falls, 
and then clear skies and dry air prevail; the temperature also 
changes, often rising before a storm and falling afterward, 
although the exact sequence depends on the location of a region 
in respect to the ocean and to the center of the storm ; the daily 
range of temperature also varies, for in damp or cloudy weather 
the nights do not become so cool nor the days so warm as when 


the air is clear. To understand the influence of the weather all 
these conditions must be investigated. Most of them, however, 
appear to be of relatively slight importance when considered by 
themselves. For instance, Lehmann and Pedersen could find no 
appreciable effect of the pressure of the atmosphere except 
where low pressure prevails a long time. The decrease in effi- 
ciency at such times, however, is probably due more to pro- 
longed cloudiness and its attendant circumstances than to the 
barometric conditions. My own work leads to the same result. 
The curves of efficiency compared with pressure are so contra- 
dictory that it does not seem worth while to publish them. The 
same is true of the range of temperature from day to night, and 
of the direction and force of the winds. I have no doubt that all 
these matters are important, and that some day their effect will 
be worked out. In general, however, their influence is exerted 
indirectly through changes in temperature and humidity. In 
hot weather a great range from day to night is unquestionably 
highly favorable, but at ordinary temperatures it seems to make 
no special difference, except through its effect upon the mean 

As to the winds, Dexter, in his book on Weather Influences, 
shows that they produce a marked effect upon the nerves, as is 
indicated by the unruliness of school children in Denver when 
high south winds prevail. Part of this is doubtless due directly 
to the wind, but the unseasonably high temperature and extreme 
dryness which accompany it are probably more important. Yet 
we are all conscious of the effect of a steady high wind. Some 
people are stimulated. I have seen a small boy, who was usually 
very quiet, climb to the top of a tall tree when a violent wind 
came up, and swing in the branches, singing at the top of his 
voice. For a while such stimulation is probably beneficial, but if 
continued day after day it makes people excitable and cross. A 
striking example of the effect of a prolonged wind is seen in 
eastern Persia in the basin of Seistan. During the summer, from 


June to September, the so-called "Wind of One Hundred and 
Twenty Days" blows so violently from the north that in the 
oases trees cannot grow except under the lee of high walls. The 
acrid wild melon, which ripens its beautiful little green and 
yellow fruit in the desert, does not spread its slender branches in 
all directions after the common fashion of plants. The gales 
crowd the branches into a sheaf which points so uniformly in 
one direction, a little to the west of north, that it can safely be 
used as a compass. When Europeans have to endure this wind 
they say that it is one of the most trying experiences imaginable. 
Not only does it render them irritable, but it deadens their ini- 
tiative and makes them want to stay idly in the shelter of the 
house. The natives, although possessed of many good qualities, 
are inert and inefficient even in comparison with their fellow 
Persians who live farther to the north and west. On the whole, 
we may probably conclude that occasional short-lived gales and 
frequent light or moderate winds are beneficial, while long 
periods either of steady calms or of gales are depressing. 

Aside from the conditions of weather already mentioned, 
there are two whose effect appears plainly when curves are con- 
structed according to the method described above. One is the 
change of temperature from one day to another, and the other 
is the character of the day as to clouds and sunshine. In con- 
sidering changes of temperature from one day to the next, we 
deal with the mean temperature for each day and not with the 
extremes. A change of as much as 15 is rare. Suppose that the 
thermometer stands at 60 at sunrise, rises to 80 by two 
o'clock in the afternoon, then falls rapidly to 50 at sunset and 
to 40 by midnight. Suppose also that the next day the tempera- 
ture is 40 at sunrise, rises a little above 55 during the day, 
and falls again to 45 at night. The two days would be very 
different, and we should speak of them as being marked by a very 
great change of temperature, a difference of 40 within ten 
hours. Yet the average of the first day would be about 64 and 


of the second 49, a difference of only 15 in the mean tempera- 

On the basis of this supposition the reader can estimate the 
importance of the various degrees of change indicated in Figure 
11. At the left the curves show the average efficiency on days 
when the temperature has fallen ; in the middle are the days with 
no change ; and at the right are the days characterized by a rise. 
Taking only the two upper curves, those for men and girls in 
Connecticut factories, the resemblance is striking. When we con- 
sider the heterogeneous character of the original materials the 
resemblance is still more important. The men's curve is based 
on 120 men at Bridgeport in 1910 and 1911, and on 180 men 
at New Britain in 1911, 1912, and 1913. The girls' curve is 
based on 196 girls at New Britain in 1911, 1912, and 1913, and 
on 60 girls at New Haven in 1913 and 1914. Even when the girls 
and men are working in the same factory, there is no reason, 
aside from the weather, why their wages should be high on the 
same day. The chief difference between the two curves is that 
the one for the girls varies more than that for the men, and 
reaches its maximum slightly farther to the right. Apparently, 
here, just as in the case of mean temperature, the girls because 
of their age or sex are more subject to the influence of the 
weather than are the men, and hence their curve dips deeper. 

Let us now interpret the upper curves, beginning at the 
middle. There they fall to their lowest level. This means that 
when the temperature of today is the same as that of yesterday, 
people work more slowly than after a change, no matter whether 
the change is upward or downward. A variable climate is there- 
fore highly desirable if people are to be efficient. Perhaps the 
most surprising feature is that the lowest point of the physical 
curve, and a depression of the mental curve, C, come not at 0, 
but at 1. The zero point is low, lower than any point of the 
physical curves except 1. Hence, our conclusion as to the 
injurious effect of uniform temperature is justified, but that 

Fall of Temperature 
-14F -12 -10 -8 -6 -4 -2 


Rise of Temperature 
"H +6 +8 +10 








Figure 11 Human Activity and Changes of Mean Temperature 
from Day to Day 

A. 300 Men in Two Connecticut Factories, 1910-13. 

B. 259 Girls in Two Connecticut Factories, 191 1-18. 

C. 460 Students in Mathematics and English at West Point and Annapolis, 1900-1911 

D. 760 Cigar-makers at Tampa, Fla., in Winter (October-March), 1912 and 1013. Factory A. 

E. 400 Cigar-makers at Tampa in Winter, 1913. Fac'- B. 

F. 400 Cigar-makers at Tampa in Summer (April-September), 1913. Factory B. 

G. 380 Cigar-makers at Tampa in Summer, 1912. Factory A. 
H. 880 Cigar-makers at Tampa in Summer, 1913. Factory A. 







does not explain the curious dip at 1 . The repetition of the 
same phenomenon in each of the three upper curves, and a simi- 
lar occurrence at 2 and 3, respectively, in the two curves 
for the winter in Florida strongly suggest that we are con- 
fronted by a peculiarity which pertains to man as a species, in 
the same way that a double optimum of mean temperature per- 
tains to wheat as shown in Figure 9. Possibly, a slight fall in 
temperature causes people to shiver, as it were, and only when 
the fall is slightly larger is the circulation of the blood so stimu- 
lated as to increase the activity of the various organs. In the 
South it may be that people's blood is more sluggish than in the 
North, so that the reaction due to cooler weather does not 
follow quite so soon, and hence the period of shivering is not 
over until the fall in mean temperature amounts to more than 
about 3. I do not assert that this is so, but it is the only expla- 
nation that comes to mind. 

To go on with our interpretation of the physical curves, a 
slight rise of temperature seems to be favorable, but beyond 
that the favorable effects of increased heat, which are strong in 
cold weather, are neutralized by the unfavorable effects in warm 
weather. In fact, our personal experience tells us that even 
when the heat is not extreme, a sudden rise may make us un- 
comfortable and lazy, as often occurs in the spring. In spite of 
this, however, a rise is in general better than uniformity. When 
the temperature falls, on the other hand, a distinct stimulus is 
received, provided the fall amounts to as much as 4. The best 
effects are seen with a fall of from 6 to 9 with girls and of 
7 to 11 with men. Here again the implication is that men are 
on the whole less sensitive than girls. An extreme drop is not 
so favorable as one of more moderate dimensions, especially for 
the girls. Taking the physical curves as a whole, the greatest 
amount of energy would be expected in climates where the mean 
temperature first rises 2 or 3 a day for a few days and then 
drops 4 to 8 a day. If the changes are greater than this, the 


effect is still stimulating, but not so beneficial as under the more 
moderate conditions. If there is practically no change, on the 
contrary, the level of efficiency lies within the low central de- 
pressions of our curves, and is less than under either of the other 

Mental work resembles physical, but with interesting differ- 
ences. When the temperature falls greatly, mental work seems 
to suffer more than physical, and declines as much as when there 
is no change. It receives a little stimulus from a slight warming 
of the air, but appears to be adversely affected when the air 
becomes warm rapidly. This last statement, however, must be 
qualified. The physical curves are based on the complete year, 
and the conditions of summer have an opportunity to balance 
those of winter. The results show the net effect for all seasons 
combined. The mental curves, on the other hand, do not include 
the summer vacation, which lasts from the middle of June to the 
first of September at West Point, and from the middle of May 
to the first of October at Annapolis. If this were included, the 
effect of a pronounced lowering of the temperature would be 
more noticeable than at present, for such a lowering is naturally 
more stimulating in July than in January. In another respect, 
also, the curve of mental efficiency needs modification. It is based 
on figures from two climatic provinces, namely, southern New 
York and Maryland. The great decline at times when the tem- 
perature rises rapidly is due largely to conditions in Maryland, 
where the hot days of the spring are much more debilitating than 
in New York. The students belong to a race which has never 
learned to endure sudden heat. Hence they feel it strongly. If 
allowance is made for the two conditions just mentioned, the 
mental curve will approach much more closely to the physical. 
A drop of temperature amounting to 8 or more will appear 
more stimulating than now seems to be the case, and a rapid 
rise will not seem so harmful. Hence, the general conclusion for 
both physical and mental activity will be essentially the same. 


It may be summed up thus : Taking the year as a whole, uni- 
formity of temperature causes low energy ; a slight rise is bene- 
ficial, but a further rise is of no particular value ; the beginning 
of a fall of temperature is harmful, but when the fall becomes 
a little larger it is much more stimulating than a rise ; when it 
becomes extreme, however, its beneficial qualities begin to decline. 
This conclusion must, of course, be appropriately modified ac- 
cording to the season. A cold wave in January is very different 
from one in July. In our curves we have given January and July 
an opportunity to neutralize one another. They have not done 
so. This means that after all allowances have been made for the 
seasons, the total effect of cold waves is decidedly beneficial, and 
of warm waves slightly so. Frequent changes, therefore, are 
highly desirable. 

Let us pass on now to the Florida curves. Here we find a 
curious difference between summer and winter which is not easy 
to understand. Let us leave that for the moment, however, and 
consider only the two winter curves. Their general resemblance 
is marked. The differences at the extremities are not important 
because the number of days there concerned is very small. It must 
be remembered that the two curves are from independent and 
rival factories. The position of any particular point in either 
curve depends upon a number of days scattered irregularly 
through the months from October to March. Aside from a genu- 
ine effect of climate, there seems to be no possible way in which 
400 men in one factory in 1913 could be made to work so that 
their curve would be the same as that of 380 men in another 
factory in the two years 1912 and 1913. Here, as in Connecticut, 
West Point, and Annapolis, we are apparently dealing with a 
peculiar quality which is inherent in the human species. 

One of the Florida curves, E, is low at 0, while the other is 
medium. This means that days when there is no change of 
temperature are not particularly favorable. At plus 2 to plus 
4, however, both are fairly high, which indicates that a moder- 


ate rise of temperature is favorable. A further rise seems to be 
harmful. The effect of a slight fall of the thermometer has al- 
ready been discussed. A further fall is beneficial. The most 
notable thing about curves D and E is the maximum from 4< 
to 7. It comes at about the same place as the mental maxi- 
mum, and is similar to the Connecticut maximum except that the 
people in the far South do not seem to be able to stand such 
extreme changes as do those in the North. In fact, it seems most 
significant that the Connecticut men, who are the strongest of 
our various groups, are most stimulated by a strong change of 
temperature. The Connecticut girls come next, but, being less 
sturdy, they do not profit quite so much by rigorous conditions. 
The mental curve is largely determined by Annapolis, and as the 
climate there is less severe than in Connecticut, the students seem 
to feel more keenly the effects of extreme changes, although they 
are stimulated by those of moderate dimensions. The same is 
still more true of the people of Florida in winter. Finally, during 
the summer the Floridans are stimulated by a slight drop of 
temperature, provided it is not enough to make them feel chilly, 
but enough to start their blood in motion. A greater drop makes 
them feel cold, while even the slightest rise of temperature in 
their long monotonous summer is unfavorable. 

We are ready now to sum up our results. The outstanding 
point is that changes of temperature, provided they are not too 
great, are more stimulating than uniformity, while a fall is more 
stimulating than a rise in the latitudes now under consideration. 
The effect of changes depends largely upon the degree to which 
people are inured to them. When they are weakened by a long hot 
period like that of the Florida summer, even a slight cooling of 
the air brings relief and activity, provided it does not go so far 
as to make people feel chilly. When the same Floridans become 
wonted to the somewhat sterner, albeit mild air of their winter, 
the first effect of a lowering of the temperature may be to make 
them shiver, but soon they are stimulated, and work fast. They 


are not so tough, however, as to be able to get benefit from the 
occasional days when really strong cold waves sweep down 
upon them. On the other hand, a rise of temperature stimulates 
them, unless it is of considerable severity. Farther north the 
same applies except that, being tougher, the people are more 
benefited by strong changes. Judging by the difference between 
summer and winter in Florida, it looks as if a little hardening 
would cause even the Cubans to respond favorably to changes 
at least as severe as those in Maryland, thus making the left- 
hand part of their curve like C in Figure 11. Taking it all in all, 
the one thing that stands out preeminently is that a fall of from 
4 to 7 is everywhere stimulating, provided people are accus- 
tomed to it. 

Man is not the only organism that is benefited by changes of 
temperature. Numerous experiments have shown that plants 
are subject to a similar influence. If a plant is subjected to un- 
duly low or high temperature, its growth is retarded. As the 
temperature approaches the optimum, the rate of growth in- 
creases. When the optimum is maintained steadily, however, not 
only does the increase cease, but retrogression sets in, and the 
rate of growth declines. A moderate change of temperature away 
from the optimum and then back again after a few hours checks 
this decline, and keeps the plant at a maximum degree of ac- 
tivity. Thus conditions where the thermometer swings back and 
forth on cither side of the optimum are distinctly better than 
where the optimum is maintained steadily. Thus it seems to be 
a law of organic life that variable temperature is better than 

The physiological process by which frequent changes of tem- 
perature affect the body is not yet known. The best suggestion 
seems to be that of Dr. W. B. James. It is universally recognized 
that one of the most important of the bodily functions is the 
circulation of the blood. The more active and unrestricted it is, 
the more thoroughly is the whole system nourished and purified. 


Provided it does not impose an undue strain on the heart or 
arteries, anything that stimulates the circulation appears to be 
helpful. Changes of temperature are a powerful agent to this 
end. Witness the effect of a bath, either cold or very hot. Few 
things are more stimulating than a Swedish bath. An attendant 
holds two hoses, one with cold water and the other with hot, and 
plays them alternately upon the patient. A man goes into such a 
bath with hanging head and dragging feet. He comes out with 
head erect and a new spring in his walk. Apparently, frequent 
changes of the temperature of the air produce much the same 
effect. No one change produces so pronounced an effect as a 
Swedish bath, but the succession of stimuli due to repeated 
changes throughout the year must be of great importance. 

Before leaving this subject, let us test the effect of changes 
in still another way. Let us see what happens during an average 
series of days such as make up our common succession of weather 
in New England. The ordinary course of events is first a day or 
two of clear weather, then a day or two of partly cloudy weather, 
next a cloudy day with or without rain, and finally another 
cloudy day during which rain falls. Then the sky clears in prepa- 
ration for another similar series. On this basis I have formed the 
six groups indicated at the top of Figure 12. At the left, the 
efficiency on all clear days which follow cloudy or partly cloudy 
days has been plotted, just as in another diagram we plotted 
the efficiency on Mondays. Next come the clear days which follow 
another clear day. If several of these follow in unbroken suc- 
cession, they are all included, but a third or fourth clear day is 
rare. In the next group come the partly cloudy days which 
follow either a clear or a cloudy day. The great majority follow 
clear days. A second partly cloudy day is much rarer than a 
second clear day, and a third is still rarer. The first cloudy day, 
the fifth column, includes cloudy days which follow either clear 
or partly cloudy days. Finally, the sixth column includes not 
only the second cloudy day, but the third and fourth if such are 



recorded. In general, this column represents days when a storm 
comes to an end, while the one to the left of it represents the 
time when a storm first becomes well established. The rest of the 
diagram, to the right of the sixth column, is merely a repetition 
of the part already described. It is inserted to show how an ideal 
series of storms would repeat itself. 

Figure 12 discloses some surprising facts. For instance, the 
first clear day is characterized by the slowest work in the two 






Figure 12. T'ie Stimulus of Storms 

(1) 60 Men at Bridgeport, 1910. 

(2) 60 Men at Bridgeport, August, 1911-July, 1912. 

(3) 170 Men and Girls at New Britain, 1913. 

(4) Weighted Average of (1), (2), and (.!), Ktiual to 2PO People for One Tear. 






upper curves and by almost the slowest in the third. Our im- 
pression of the stimulus of the bright, clear air after a storm 
receives a flat contradiction. It is apparently psychological, 
not physical. The second clear day makes a better showing than 
the first. It stands high in two curves, and low in only one. The 
first partly cloudy day is high in one curve, and medium in two. 
The second partly cloudy day is medium in all three. The same 
is true of the first cloudy day. The last cloudy day is as sur- 
prising as the first clear day. In each of the three curves it 
stands highest. People work fastest at the end of a storm. In the 
lower curve of Figure 12, the whole matter is summed up in a 
single line. Here we see that during an average "spell of weather" 
people are least efficient on the clear days ; moderately efficient on 
the partly cloudy days, and on the first cloudy day ; and most 
efficient at the end of a storm. We may tell ourselves that this is 
unreasonable, but when we think it over, we are likely to be 
aware of its truth. Before a storm we may feel depressed, but at 
the end, when the rain or snow is almost over and the air begins 
to have that excellent quality which makes us forget all about 
it, we bend to our work with a steadiness and concentration 
which are much less common at other times. Hellpach empha- 
sizes this in his book on the psychological effect of geographical 
conditions. We fail to appreciate it largely because the aesthetic 
impressions of a beautiful, clear day are felt much more con- 
sciously than are the physiological conditions which throw us 
vigorously into our work. Each storm, with its changing skies, 
varying humidity, and slow rise and rapid fall of temperature, 
is a stimulant. Each raises our efficiency. 

This ends our survey of the effect of climate upon daily work 
in the eastern United States. We have considered the influence of 
the seasons, of mean temperature, of humidity, of winds, of 
changes of temperature from day to day, and of the character 
of each day and its relation to storms. We have also seen that 
although different races, or people under decidedly diverse cli- 


matic environments, are at their best at slightly different tem- 
peratures, the differences are inconsiderable, and changes of 
temperature are as valuable to one as to the other. The question 
now arises whether the climatic effects are really of great im- 
portance. In Figure 12, the stimulus of the succession of clear 
and cloudy days amounts to only 1 per cent. In Figure 11 
changes of temperature from day to day produce a variation 
of only a little over 2 per cent, if we omit the irregular and un- 
reliable extremities of the curves. In Figure 4, the maximum 
effect of humidity appears to be only 3 per cent. In Figure 8, 
however, the differences are greater, for the effect of mean 
temperature upon the girls in Connecticut is 7 per cent. Finally, 
in Figure 1, the effect of the seasons reaches nearly 9 per cent 
when four years are averaged, and nearly 15 per cent for indi- 
vidual years. 

These figures are far from representing the full importance 
of the various factors. This will readily appear from a little 
consideration. In the preceding paragraph, the percentages in- 
crease in proportion to two conditions, first, the degree to which 
the influence of a single factor is separated from the influence 
of all other factors, and second, the length of time during which 
each factor is able to exert its influence. The smallest figure, 1 
per cent in Figure 12, does not represent any individual factor, 
unless it be cloudiness. It does not even represent the fluctua- 
tions which attend an individual storm, for the days were selected 
without regard to their position in a cyclonic disturbance, but 
simply according to their cloudiness. The variations shown in 
the curve are due to many factors, including mean temperature, 
changes of temperature, relative humidity, and others of minor 
importance. As no two of these are necessarily at their maximum 
at the same time, they neutralize one another. Moreover, a given 
condition lasts only a day in most cases, and so has no oppor- 
tunity to produce any great effect. In the curve of changes of 
temperature from day to day, which shows the next larger 


effect, a single factor is singled out. Its full force can by no 
means be seen, however, for the humidity often varies in such a 
way as to neutralize it. Moreover, the effects of especially low 
or high temperatures may often completely overshadow any 
stimulus arising from the mere fact of a change. Furthermore, 
the effect of changes of temperature rarely continues more than 
two days. For example, if the thermometer averages six degrees 
lower on one day than on the preceding, it may happen that there 
will be a further drop before the next day, but there is far more 
chance that the temperature will rise a little or remain station- 
ary, or fall so little that it will not be stimulating. Hence, the 
effect is rarely cumulative, and the influence of each single day 
must usually stand by itself. Much the same is true of relative 
humidity, except that by heating our houses we artificially in- 
duce long periods of great aridity. The effects of mean tempera- 
ture, on the other hand, have greater opportunity to show their 
full importance, though they, too, are hampered. Relatively low 
or high temperatures last many weeks, which makes it possible 
for the effect of day after day to accumulate. Yet our curves 
by no means show the full effect, for a cold day with a mean 
temperature of 30 may come in November at a time when effi- 
ciency is still at its highest. It produces its normal effect, but a 
single unpropitious day, or even a week, does not suffice to de- 
press people's vitality to a degree at all approaching the low 
limit reached after two months of cold weather. Likewise, a day 
with the most favorable temperature, not far from 60, may be 
sandwiched between very hot days in July, or between two cold 
days in March. Hence, people will display little energy on those 
particular days, and the average efficiency at the optimum tem- 
perature will appear correspondingly lower than it ought. 
Finally, the seasons have more opportunity than the individual 
climatic elements to produce their full effect. Even here, how- 
ever, the variability of our climate does not allow any special 
combination of circumstances to work long unimpeded. Warm 


waves break the cold periods of winter, and cool waves come in 
summer. Storms are more active in winter than in summer, and 
hence their stimulus works toward overcoming the effect of pro- 
longed cold. Moreover, no single season is of great duration, and 
extreme conditions do not last long enough to produce their full 
effect. From all this we may conclude that the total influence of 
climate upon energy is much greater than appears in any one 
of our curves. 

The difficulty of determining the exact proportions of any 
individual influence may be made clear by an example. We know 
that man's power to work depends upon food, drink, sleep, and 
clothing. Suppose that while he was still supplied with these in 
normal quantities we were to try to measure the effect of each. 
We should test his strength at stated intervals after he had 
eaten his meals, or after he had had a drink. We should find out 
how many hours he slept each night and compare that with his 
work. We should measure his achievements before and after he 
put on his spring underwear or fall overcoat. We might get re- 
sults, but it is highly doubtful whether they would be as distinct 
as those here discussed. We have no difficulty in measuring the 
effect of food, drink, sleep, and clothing, for we can easily vary 
them to suit the needs of our experiment. With climate the case 
is different. We must take it as we find it, and must experiment 
on people who are constantly subject to its influence. Some day 
we shall test people first in one climate and then in another, but 
that will be difficult because it takes a considerable time for cli- 
mate to produce its full effect. Being obliged to search for the 
effects of climate without being able to change them in accord- 
ance with the needs of our experiment, we are in almost as diffi- 
cult a case as the experimenter who should desire to determine 
the effect of the amount and kind of food consumed by a group 
of individuals, but who had no control over how much they ate. 
They might allow him to measure what was set before them at 
each meal and what remained when it was over, but they would 


eat as much as they liked and when they liked. He would get 
results, if he did his work carefully, but they would by no means 
represent the full effect of food. 

The influence of climate upon men may be likened to that of 
a driver upon his horse. Some drivers let their horses go as they 
please. Now and then a horse may run away, but the average 
pace is slow. Such drivers are like an unstimulating climate. 
Others whip their horses and urge them to the limit all the time. 
They make rapid progress for a while, but in the end they ex- 
haust their animals. They resemble climates which are always 
stimulating. In such climates nervous exhaustion is likely to 
prevail and insanity becomes common. A third type of drivers 
first whip their horse to a great speed for a mile or two, and then 
let them walk slowly for another mile or two. They often think 
that they are accomplishing great things, and they are better 
off than the two types already mentioned, but they still have 
much to learn. They are like a climate which has a strong con- 
trast of seasons, one being favorable and the other unfavor- 
able. Still a fourth kind of driver may whip his horse sometimes 
and sometimes let him walk, but what he does chiefly is to urge 
the animal gently with the voice, then check him a little with the 
rein. By alternate urging and checking he conserves the animal's 
strength, and in the long run can cover more distance and do it 
more rapidly than any of the others. Such a driver resembles a 
climate which has enough contrast of seasons to be stimulating 
but not to create nervous tension, and which also possesses fre- 
quent storms whose function is to furnish the slight urging and 
checking which are so valuable in the total effect, although each 
individual impulse is almost unnoticeable. 


WE have investigated the relation of the weather to human 
energy. Let us do the same for health. In a previous 
chapter we saw that variations in the death rate in New York 
and Japan and the gain in weight among tubercular patients 
exhibit seasonal fluctuations much like those of workers in fac- 
tories. As a means of measuring health, deaths are more im- 
portant than disease for two reasons. First, experience has 
shown that when several years are averaged together, the death 
rate is an almost perfect measure of the number and severity of 
the diseases which afflict a community. Second, the records of 
disease are very scanty and imperfect ; they have never been 
tabulated on any large scale for the entire population. Only in 
rare cases can the records of certain diseases be used as well 
as those of deaths. Accurate mortality records, on the contrary, 
have now been kept for many years. 

The health of practically every community varies in response 
to the seasons. In the northern United States most physicians 
are far busier in February and March than in May and June. 
In July and August the demand for their services increases 
again, especially among children. Then come the best months of 
the year, especially October, when good health and good spirits 
abound. Different types of disease, to be sure, display different 
seasonal adaptations. Those of the respiratory organs, for ex- 

* This chapter and the two that follow are entirely new. They are based 
largely on publications mentioned in the list at the end of the prefaces, but 
none of the material in Chapter IX has hitherto been published. 



ample, reach a maximum in winter, while those of the digestive 
tract are more numerous in summer. 

Admitting, then, that both energy and health show marked 
seasonal variations, our aim is to determine how closely the two 
sets of variations are in harmony. Part of the answer is illus- 
trated in Figure 13. The upper line, A, represents variations in 

1010 mi 1*12 1913 


Figure 13. Seasonal Variations in Energy and Health 

A. Work of factory operatives in Connecticut. 

B. Work of factory operatives in Pennsylvania. 

C. Health (death rate inverted) in Connecticut. 

D. Health (death rate inverted) in Pennsylvania. 

Scale for A and B on left, for C and D on right. B and D are placed below A and C for con- 
venience, although belonging at essentially the same level. 

the efficiency of factory workers in Connecticut from January, 
1910, to December, 1914, as already given in Figure 1. The 
second line, B, is the similar curve for Pittsburgh. The two lower 
lines illustrate fluctuations in health in Connecticut (C) and 
Pennsylvania (D). They are the curves of the death rate in- 
verted so that high parts indicate good conditions or few deaths, 
and low parts, poor conditions or many deaths, thus per- 
mitting easy comparison with the efficiency curves. It is ob- 


vious not only that the two efficiency curves and the two health 
curves run almost parallel, but that there is also a close parallel- 
ism between health and efficiency. Aside from the weather all 
possible causes of such parallelism seem to be excluded, for epi- 
demics, business disturbances, and the like, did not occur in such 
a way as to explain the similar fluctuations in two diverse phe- 
nomena hundreds of miles apart. 

Note how closely the four curves agree even in details. Low 
efficiency during January, 1910, is followed in a month or two 
by very poor health. During the spring both efficiency and 
health improve. Then comes the summer with a mild tendency 
toward a drop in all the curves, and the autumn with the main 
maximum of the year. In 1911 the parallelism of the four curves 
is again evident, as is the lag of the mortality curve after that 
of efficiency. In 1912 and 1913 the sag of all the curves in sum- 
mer diminishes and disappears ; for those years, it will be re- 
membered, had only short periods of really hot weather. The 
similarity of the four curves, especially in the summer, would 
be still more marked were it not that the deaths of children under 
two years of age have been omitted in the mortality curves. 

Since many other observations point in the same direction, 
we conclude that unfavorable weather, such as commonly pre- 
vails in January, has an immediate effect in reducing people's 
vitality and energy. Hence their work falls off. At the same time 
they become more susceptible to disease. Accordingly, in due time 
the number of deaths increases. Naturally the greatest mortality 
lags several weeks after the lowest efficiency ; it takes time for 
bacteria to produce infection, and for infection to lead to death. 
The lag is longer in winter when respiratory diseases are the 
chief enemy than in summer when digestive diseases with their 
more rapid course are the chief foes. The agreement between 
health and energy is thus so close that both appear to depend 
npon essentially the same fluctuations of the weather. 

It is especially important to determine the relation of the 


weather to mental as well as physical health. Hence peculiar 
interest attaches to certain studies of mental abnormalities 
carried on by Norbury.* He finds that the admissions to psy- 
chiatric hospitals show that "Mental disorders in their incipi- 
ency and recurrence parallel the efficiency curves of Huntington. 
(Maximum in the spring, minimum in the autumn.)" His curves 
show that certain maxima of admissions for mental disorders oc< 
curred at the following periods : 

Civil Hospitals of New York State, 1916-1921, June. 
Norbury Sanatorium in Jacksonville, Illinois, 1900-1923, May. 
Massachusetts State Hospital, 1922-1928, May and June. 
State Hospitals, northern United States, 1922-1923, March. 

After the maximum the diminution in admissions is in all cases 
very rapid. The number of admissions fell to the lowest point at 
the following periods : 

New York State Hospitals, September-February. 
Dr. Norbury's Sanatorium, October-February. 
Massachusetts State Hospital, November-February. 
State Hospitals, northern United States, August-February. 

Across the Atlantic insanity in London reaches a distinct maxi- 
mum in May and is low from July to February. Almost identical 
conditions prevail as to suicide, except that the fall from the 
high point in June is not so rapid as in the case of insanity, al- 
though the minimum is reached earlier, that is, in November and 
December, instead of from July to February. As to the nervous 
disorders in continental Europe, Gamier states that general 
paralysis in Paris follows a seasonal course almost identical 
with that of insanity in London. Now nervous breakdowns, in- 
sanity, suicide, and paralysis, as Norbury shows, are all due 

* Frank Parsons Norbury: Seasonal Curves in Mental Disorders. Medi- 
cal Journal and Record, vol. 119, 1924. 


mainly to the same cause, namely fatigue of the nerves. Such 
fatigue, he says, is apparently controlled to a large degree by 
the seasons. But just as the maximum number of deaths lags 
some weeks or even a month or two after the time when the 
weather produces the lowest efficiency in factories, so the maxi- 
mum effect of fatigue of the nerves lags still more, and the great- 
est number of nervous breakdowns may occur three or four 
months after the period of least efficiency as measured by daily 

The universality with which the bodily functions respond to 
the seasons may be judged from two other recent investigations. 
In one case Hess* has shown that among infants the phosphates 
of the blood, which are an essential element for growth, show a 
pronounced seasonal tide. During the year covered by his ob- 
servations the percentage of phosphates in the blood stood at 
4.34 mg. per cent during June and July, 1921. It may have 
risen higher during the succeeding months, but no records were 
kept. In December it had fallen to 3.92 and in March to 3.58. 
Pi'esumably it would have fallen still lower, but whenever the 
phosphates fell below 3.75 the children were treated with ultra- 
violet light, which effectively increases not only the phosphates, 
but also the calcium and probably other important elements of 
the blood. It has been found by many authorities that the chil- 
dren's disease known as rickets follows a seasonal course like 
that of the phosphates and is connected more or less closely with 
the amount of ultra-violet light. For our present purposes, how- 
ever, the important point is that the essential phosphates in 
children show the same general seasonal variation as the death 
rate, and as mental breakdowns among adults, the lag being 
perhaps greater than in the death rate but less than in mental 

"Alfred F. Hess: A Seasonal Tide of Blood Phosphate in Infants. Th* 
Journal of the American Medical Association, December 30, 1922, vol. 79, 
pp. 2210-2212. 


Another case of seasonal fluctuations is discussed by Porter* 
of the Harvard Medical School. In cooperation with the Health 
Department of Boston, monthly records of the weight of several 
thousand of the youngest school children were begun in 1909 and 
continued until 1919. Among the boys born in 1905 the average 
increase in weight from month to month during the years 1911 
to 1918 was as follows : 

January to February -{-0.18 Ibs. July to August -f0.801bs.f 

February to March -{-0.4/7 August to September -}-0.93t 

March to April -f-0.22 September to October -f 0.96 

April to May 0.16 October to November -f 0.61 

May to June -j-0.05 November to December -|-0.63 

June to July -fO.SOf December to January -fO.98 

In interpreting this table, allowance must be made for cloth- 
ing. In May the children exchange their winter clothes for those 
which are somewhat lighter, while about the end of September 
the opposite change takes place. Allowance must also be made 
for the long summer vacation with its opportunities for out- 
door play which naturally causes the children's weight to in- 
crease rapidly. If allowance is made for these two facts the 
regularity of the seasonal trend of growth is intensified. From 
January onward the children grow slowly ; in the spring after 
the phosphates have reached the minimum and at the very time 
when grown people are most subject to mental breakdowns, the 
children practically cease to grow. Not until the summer vaca- 
tion begins do they recover from the effect of the winter. In the 
summer the fourfold advantages of freedom from school, favor- 
able weather, much outdoor life, and a more varied and healthful 
diet than at other seasons cause rapid gain in weight. This gain 

* W. T. Porter: The Seasonal Variations in the Growth of Boston School 
Children. American Journal of Physiology, May, 1920. 

f The boys were not weighed during the summer vacation. The average 
increase in weight from June to September was 2.23 pounds, and this has 
been allotted to the summer months in what seem to be reasonable propor- 



seems to be checked somewhat when school begins, but is resumed 
during the late fall and early winter. In spite of confinement in 
school, little outdoor play, and a diet relatively poor in vita- 
mines and other important elements, the children gain weight 
more rapidly in December than in any other month except 
perhaps at the end of the summer vacation. The chief favorable 
factor appears to be the climate, the stimulus of which does not 
disappear until the advent of really cold weather. The sudden 
decline in the children's rate of gain during January appears to 
correspond closely with the drop in the efficiency of factory 
workers at about the same time, but the effect on growth lasts 
much longer than does the more direct effect upon activity. 

Among the many other instances of seasonal fluctuations in 
human health, one of the most remarkable is illustrated in 
Figure 14. The upper line indicates for each month the average 

Apr May June July Aug Sept Oci 

Deo Jcu> 






Figure 14. Seasonal Variations in Conceptions and Deaths in Japan, 



daily number of conceptions which resulted in the birth of living 
children in Japan during the ten years from 1901 to 1910. A 
pronounced maximum in June is followed by a diminution of 46 
per cent, which culminates in September at the end of the long, 
hot, humid summer. Then comes a recovery which is checked but 
not reversed during the winter, and which resumes its course 
during the delightful spring weather of April, May, and June. 
The second curve shows the average number of deaths per day. 
It is almost exactly the reverse of the curve of conceptions. In 
other words, during the months when many people are sick and 
die, the number of conceptions is either very low or else a large 
number of conceptions result in miscarriages or still-births. The 
most extraordinary feature of Figure 14 is the fact that the 
curves of conception and mortality cross one another in Sep- 
tember. The same fact is illustrated in the lowest curve, which 
indicates the excess of conceptions over deaths. In June the 
conceptions which give rise to living children outnumber the 
deaths by nearly 2.5 to 1. In September the conceptions are less 
numerous than the deaths. No seasonal variations in farm work 
or social customs seem competent to explain more than an in- 
significant part of the great contrast between May and Sep- 
tember. The explanation seems to be that the hot, humid summer 
saps the vitality of the Japanese, especially the women, so that 
they are physically unable to reproduce themselves. If the 
weather which prevails in July and August should prevail 
throughout the year, the Japanese as a race would apparently 
diminish in numbers instead of increasing with disquieting rapid- 
ity. Under such circumstances natural selection would presum- 
ably work with great vigor. A race might arise capable of 
withstanding the most intense tropical conditions, but it would 
presumably differ from the present Japanese in many qualities 
such as energy and initiative. 

It would be easy to multiply examples, but space forbids. All 
sorts of physiological conditions appear to vary from season 


to season in essentially the same way except that some responses, 
such as the energy of people in good health, lag only a little after 
the climatic conditions, others, such as diseases and the rate of 
reproduction, lag several weeks ; and still others, such as the 
growth of children and the occurrence of nervous breakdowns 
and suicides, lag still farther. In the case of the mental disturb- 
ances the lag is so great that it almost seems as if the onset of 
stimulating weather after a period of unfavorable weather, 
had the effect of causing a sudden collapse. In reality the real 
state of affairs may perhaps be this : the winter months produce 
an effect like that of driving a horse without rest and as rapidly 
as possible over a bad road. When a stretch of good road is 
reached the driver, to whom we may liken the weather, whips the 
animal to his topmost speed and the tired beast soon breaks 

Let us now try to analyze the effect of the seasons upon health, 
and determine the relative part played by temperature, humid- 
ity, and variability. A study of about nine million deaths by 
means of climographs as described in World Power and Evolu- 
tion, leads to the conclusion that the optimum or most favorable 
condition for human health is an average outside temperature 
of about 64 F. (18 C.) for day and night, a relative humidity 
of about 80 per cent, and a fairly high degree of storminess, or 
at least of variability from day to day. This means a climate in 
which the midday temperature rises to 70 more or less, while 
that of the night falls below 60. With the rise in temperature 
the noonday relative humidity declines to perhaps 60 per cent, 
while during the cool night it rises high enough so that dew is 
precipitated. But a constant succession of clear days is not 
desirable. There must be occasional rains and variations in tem- 
perature, wind, and cloudiness from day to day. Tampa experi- 
ences such conditions at the end of February, New Orleans in 
March, Asheville in May, Atlantic City in early June, Seattle 
in August, Nantucket and Boston in September, and Portland, 



Oregon, in October. At the seasons when people go in largest 
numbers to many famous health resorts the majority of such 
places enjoy climatic conditions closely approaching those 
which are ideal for physical health. 





of change 


No. of 


of 10F. on 

Nature of criteria 



death rate 

1. Deaths, north Italy, 1899-1913 




2. Piece-work, men, two Connecticut 

factories, 1910-1913 



3. Piece-work, girls, one Connecticut 

factory, 1911-1913 



4. Deaths, British Columbia, 1914- 





5. Deaths, southeastern United States, 





6. Piece-work, Pittsburgh, 1910-1913, 




7. Deaths, southern Italy, 1899-1913 




8. Cigar-making, Cubans, Tampa, 

Florida, 1913 



9. Deaths, southern France, 1901-1910 




10. Deaths, northeastern United States, 





11. Deaths, whites, eastern United 

States, 1912-1915 




12. Deaths, dry interior of United 

States, 1900-1912 




13. Deaths, northern France, 1901-1910 




14. Deaths, east central United States, 





15. Cigar-making, Cubans, Tampa, 

Florida, 1913 




16. Deaths, negroes, eastern United 

States, 1912-1915 




17. Cigar-making, Cubans, Tampa, 

Florida, 1912 



18. Deaths, California, 1900-1912 





The preceding table illustrates the type of statistical evidence 
on which is based the conclusion that a mean temperature of 
64 F. is the optimum. The experimental evidence will be illus- 
trated later. 

Columns A, B, and C explain themselves. Column D indicates 
the approximate percentage by which a change of 10 F. raises 
or lowers the death rate when the temperature ranges between 
30 and 60. When all seasons are taken together the net effect 
of a rise of temperature under such conditions is to lower the 
death rate, while a fall increases the death rate. This, however, 
applies only to a rise or fall in which the new condition of 
temperature endures for some time, as in the change from season 
to season. 

In twelve of the eighteen cases in this table the optimum out- 
side temperature was from 62 to 65 F., and in five cases 
64 F. Two of the cases where the optimum falls to 60 or lower 
were piece-work in Connecticut factories. This may be because 
such work involves mental as well as physical activity. We have 
found some evidence that the optimum temperature for mental 
work is considerably below that for physical work. Naturally 
an occupation where mental and physical alertness are both 
needed would be most favored by a temperature between the best 
temperatures for the body and the mind. As to the low optimum 
of the north Italians, 58, I have no explanation. The cause 
could perhaps be detected by a study of the other elements of 
the weather such as humidity and wind, or of local diseases such 
as malaria. It is worth noting, however, that Campani* from 
an analysis of 24,500 deaths at Milan obtains results closely 
similar to those here set forth. His results, to be sure, are espe- 
cially important in respect to variability rather than tempera- 
ture. He finds that deaths are least numerous just after storms 
while the wind is blowing. They are most numerous in still air 
during periods of stagnation and after periods with little change 

* A. Campani: Oazetta degli Ospeddiedelle Cliniche, Milan. 


of temperature. Changes of temperature are beneficial in north 
Italy just as in America. 

Among the three cases of the preceding table where the opti- 
mum temperature is above 65, one represents Cubans of 
Spanish descent but with a good deal of colored admixture, and 
a second represents negroes. In the first case life in a tropical 
climate has presumably raised the optimum temperature some- 
what. In the second, although the negroes here dealt with lived 
largely in the parts of the United States from Maryland north- 
ward, they probably still retained an ancestral adaptation to a 
slightly warmer climate than that which is best for the white 
race. It is worth noting, however, that the Cubans have spent 
practically their whole lives where the coolest month averages 
about 70 and the hottest over 80, while the ancestors of the 
negroes have dwelt for untold generations in regions still 
warmer. Nevertheless the optimum for both groups, 68, seems 
to be lower not only than the average temperature of their 
homes, but than the average for the coolest months in those 
homes. I might add that for negroes the optimum humidity 
seems to be a little higher than for white men. This again may be 
an inheritance from a former environment. Such differences 
between diverse races suggest that permanent physiological 
changes take place whereby races become adjusted to diverse 
climates. The slightness of the differences, however, suggests that 
such adjustment is very slow and incomplete. An earlier and 
more fundamental adjustment to climate appears still to be 
largely dominant, and may represent the climate under which 
man's chief physical evolution took place. 

As for the extreme variation in California, where 70 appears 
to be the best temperature, I am inclined to think that it is due 
to accident. The California results depend largely on two cities, 
San Francisco where the mean monthly temperature never 
reaches 70, and Los Angeles where conditions of wind and 
humidity may account for the favorable conditions during the 


months of high temperature. It is interesting to note that the 
average of the six extreme cases in the table is 64.2, against 
63.9 for the twelve medium cases. It must be borne in mind, 
however, that the best temperature is not the same in dry 
climates as in moist. We shall return to this later. 

The conclusion that an outside mean temperature of about 
64 F. is the optimum for Europeans agrees closely with the con- 
clusion now widely accepted that an inside temperature not 
above 68, and preferably lower, is the ideal. The effects of de- 
viations from this ideal have been the subject of many careful 
experimental investigations, among which those carried on by 
the New York State Ventilation Commission under the chair- 
manship of Prof. C.-E. A. Winslow are especially notable. The 
results of these experiments, as set forth in a volume entitled 
Ventilation, are so important that I shall conclude this chapter 
by quoting several pages which pertain not only to temperature 
but to other atmospheric conditions. 

"The work of previous investigators from Hermans to Leon- 
ard Hill has made it abundantly clear that extreme high atmos- 
pheric temperatures are highly prejudicial to human health and 
comfort, and that it is to such temperatures rather than to 
chemical pollution that the most serious effects of bad air are 
due. The most important result of our experiments has perhaps 
been the demonstration that even moderately high temperatures 
between 24 and 30 C. (75-86 F.) are accompanied by 
demonstrable harmful results. 

"A. Body Temperature and Circulatory Phenomena. We 
find that the rectal body temperature exhibits a definite relation 
to the temperature of the atmospheric environment, the body 
temperature when observed at 8 a. m. during the summer time 
showing a fairly close parallelism with the average temperature 
of the outdoor air for the preceding night. In our experimental 
chamber we found that at 68 F. the rectal temperature and 
heart rate tended to fall, the Crampton index of vasotone in- 


creased, the resistance of the peripheral portion of the circu- 
latory system rose, and the velocity of the blood flow was 
correspondingly lessened. At 75 F. the rectal temperature, 
heart rate, and Crampton index changed but slightly. At 86 F. 
with 80 per cent relative humidity, the rectal temperature and 
heart rate rose, the Crampton index fell, the peripheral resist- 
ance decreased and the velocity of blood flow increased. 

"The final average results attained under the three atmos- 
pheric conditions were as indicated below. 

20 C. (68 F.) 
50 per cent 

24 C. (75 F.) 
50 per cent 

30 C. (86 F.) 
80 per cent 

Rectal temperature 
Heart rate, reclining 
Heart rate, standing 
Crampton index 

36.7 C. 

37.0 C. 

37.4 C. 

"We are not prepared to say whether the maximum heart 
rates attained at 75 F. as compared with 86 F. are significant ; 
but it is clear that rectal body temperature bears a direct, and 
the Crampton index an inverse, relation to atmospheric tem- 
perature. After vigorous physical work the return of the heart 
rate to normal was somewhat more prompt at 68 F. than at 

"Systolic and diastolic blood pressure showed no very definite 
relation to temperature between 68 F. and 86 F. ; but at 
101 F. blood pressure as well as rectal temperature and heart 
rate showed marked increases. 

"B. Other Physiological Phenomena. The rate of respiration 
was slightly increased by moderately high temperatures, from 
an average of 17.9 at 68 F. to 19.3 at 75 F. and 19.7 at 
86 F. ; while at 101 F. the increase was very marked. The 
dead space of the lungs, the volume of the supplemental air, the 
alkaline reserve of the blood, the respiratory quotient, the car- 


bohydrate metabolism, the protein metabolism and the total 
metabolism showed no demonstrable relation to atmospheric 
temperature under the conditions studied in our experiments. 

"C. Comfort and Mental Efficiency. So far as the sensations 
of the subjects are concerned, as evidenced by their votes as to 
the comfortableness of the experimental chamber, the difference 
between 68 F. and 75 F. is comparatively slight; but a tem- 
perature of 86 F. with 80 per cent relative humidity is dis- 
tinctly uncomfortable, the average votes falling sharply when- 
ever this condition is reached. This discomfort is not, however, 
accompanied by any inability to perform mental work ; such as 
naming of colors and opposites, cancellation, mental multiplica- 
tion, and addition. Subjects urged to maximal performance did 
equally well under both conditions, the conditions being main- 
tained for four hours a day on five consecutive days, or for eight 
hours a day on four consecutive days. Longer hours of exposure 
continued for a prolonged period might of course yield different 
results. Even when the subject was left free to work or not, as 
much mental work was accomplished at 75 F. as at 68 F. 
although in one short experiment a temperature of 86 F. did 
seem to diminish the inclination to do mental work. At 75 F. 
typewriting (which involves a certain amount of neuro-muscular 
activity) seemed to be slightly diminished while performance in 
mental multiplication was actually increased. In general, how- 
ever, we have no clear evidence that moderate overheating im- 
pairs mental efficiency. 

"7X Influence of Atmospheric Humidity. Somewhat exhaus- 
tive studies of the alleged influence of atmospheric humidity 
upon mental achievement and comfort have yielded entirely 
negative results. With relative humidities of 50 per cent and 25 
per cent, respectively (all other conditions being the same), 
there was no significant difference in the votes of the subjects 
as to their subjective sensations of comfort, no difference in 
temperature of the air next to the chest, or in pulse rate, and 


no difference in the performance of a long series of complex 
neuro-muscular tasks specially designed to test the alleged in- 
fluence of a dry atmosphere upon nervousness and efficiency. 
Longer periods of exposure might of course produce effects not 
detected by us ; but it seems clear that exposure to a relative 
humidity as low as 25 per cent at a temperature of 75 F. for 
eight hours a day on five days a week does not produce any 
demonstrable harmful effects. 

"J. Physical Work. We have demonstrated on the other hand 
a very marked and significant influence of atmospheric tempera- 
ture upon the performance of physical work. An increase of 
room temperature from 68 F. to 75 F. caused a decrease of 
15 per cent in the physical work performed by men who were not 
compelled to maximum effort but were stimulated by a cash 
bonus ; and an increase from 68 F. to 86 F. with 80 per cent 
relative humidity caused a decrease of 28 per cent in the physical 
work performed under conditions of maximal effort:. The fall at 
75 F. was most marked in the afternoon hours when fatigue 
effects were called into play. 

"F. Susceptibility to Disease. Finally, we have found very 
definite evidence of the harmful influence of moderately high 
atmospheric temperatures, particularly if followed by sudden 
exposure to low temperatures, in promoting susceptibility to 
bacterial infection. We find that rabbits maintained at a tem- 
perature of 86 F. show a distinctly delayed formation of hemo- 
lysins and a slightly reduced agglutinative power, as compared 
with animals kept at 68 F. ; and that rabbits kept at 76- 
70 F. and then chilled to 20-50 or chilled first and kept at 
79 F. are much more susceptible to infection than animals kept 
at 65-70 F. 

"Exhaustive observations of the nasal mucosa of human sub- 
jects show that in a warm atmosphere there is an increase, in 
a cool atmosphere a decrease in the swelling, moisture, and red- 
ness of the nasal mucous membranes. Sudden change from a hot 


to a cold atmosphere, particularly when combined with drafts, 
produces a moist and distended but anemic condition of the 
mucosa, presumably highly favorable to bacterial invasion ; and 
workers who have been habitually exposed to high temperatures 
show a marked excess of atrophic rhinitis. Hot moist air (as in 
the case of laundry workers) seems to be much more harmful 
than hot dry air (as in the case of furnace men). 

"//. The Effect of Chemically Vitiated Air upon Physiological 
State, upon Comfort, and upon Efficiency 

"In parallel with our experiments upon the effect of tempera- 
ture, we also studied the possible influence of air, chemically 
vitiated by human occupancy, but at the same temperature and 
humidity as fresh air used as a control. The factor of air move- 
ment was excluded by the use of room fans to stir up both fresh 
and stale air so that no difference existed save the very slight 
changes in oxygen and carbon dioxide and the more obvious 
changes in odoriferous organic constituents due to respiration 
and effluvia from the body. 

"A. Physiological Reactions, Comfort, Mental Efficiency, and 
Resistance to Infection. In most of the reactions studied in our 
experiments the influence of chemical vitiation of the atmos- 
phere appeared to be absolutely nil. Temperature and humidity 
being the same, we compared fresh air containing 5 to 11 parts 
per 10,000 of carbon dioxide with vitiated air containing 23 
to 66 parts and found no difference in body temperature, heart 
rate, blood pressure, Crampton index, rate of respiration, dead 
space in the lungs, acidosis of the blood, respiratory quotient, 
rate of heat production, rate of digestion, and protein metabo- 

"Comfort votes indicated that the subjects were quite unable 
to distinguish from the standpoint of sensation between the fresh 
and the stale air conditions ; the performance of mental work was 
quite unaffected by the chemically vitiated atmosphere. 


"In a special series of animal experiments, guinea pigs ex- 
posed to strong fecal odors for considerable periods failed to 
exhibit any increased susceptibility to inoculations with foreign 
bacteria or to injection of diphtheria toxin. 

"B. Physical Work. In regard to the performance of physical 
work on the other hand, there appeared to be a distinctly harm- 
ful influence of the vitiated air. Temperature and humidity being 
the same, our subjects performed 9 per cent less work in stale 
than in fresh air, a difference less marked than that produced by 
warm as compared with cool air (15 per cent) but apparently 
significant. When both unfavorable conditions were combined 
(in warm and stale air) only 77 per cent as much physical work 
was performed as in cool fresh air. 

"C. Appetite and Growth. Finally we found a marked influence 
exerted by stale air upon the appetite for food as determined by 
serving standard lunches to parallel groups of subjects in stale 
and fresh air, respectively, but with the same temperature and 
humidity. In the four different scries of experiments which were 
successfully completed on this basis without the intrusion of in- 
terfering factors, the excess of food consumed under fresh air 
conditions was respectively 4.4, 6.8, 8.6, and 13.6 per cent. Since 
the probable errors involved in these experiments were relatively 
very slight it seems evident that the chemical constituents of 
vitiated air may not only diminish the tendency to do physical 
work but also the appetite for food. 

"This conclusion is strengthened from another direction by 
demonstration that exposure to strong fecal odors causes a 
restraining influence upon the rate of growth of guinea pigs 
during, but not after, the first week of exposure. 

'7/7. Practical Conclusions in Regard to Ideal Conditions of 


"The experiments of the commission have in general con- 
firmed the conclusion of earlier investigators that the first and 


foremost condition to be avoided in regulating the atmosphere 
of occupied rooms is an excessively high temperature. We have 
found that even slight overheating (75 F.) produces the follow- 
ing harmful results : 

"(1) A burden upon the heat-regulating system of the body 
leading to an increased body temperature, an increased heart 
rate and a marked decrease in general vaso-motor tone as regis- 
tered by a fall in the Crampton index. 

"(2) A slight but definite increase in rate of respiration. 

"(3) A considerable decrease in the amount of physical work 
performed under conditions of equal incentive a decrease 
amounting to 15 per cent at 75 F. and to 28 per cent at 86 F. 

"(4) A markedly abnormal reaction of the mucous mem- 
branes of the nose, leading ultimately to chronic atrophic rhini- 
tis and when followed by chill, producing a moist and distended 
condition of the membranes calculated to favor bacterial inva- 
sion. In animals exposure to high atmospheric temperatures, 
particularly when followed by chill, diminishes the protective 
power of the blood and markedly increases general susceptibility 
to microbic disease. 

"For these reasons we believe that the dangers of room over- 
heating are far more serious in their effect upon human health 
and efficiency than has generally been realized and that every 
effort should be made to keep the temperature of the school- 
room, the workroom, and the living-room at 68 F. or below. 

"With regard to the problem of relative humidity it is obvious 
that a high moisture content combined with high temperature 
must always be harmful, since the effect of a humid atmosphere 
is to decrease the heat loss from the body by evaporation. The 
specifically harmful influence of unduly low humidity which has 
been postulated by various writers upon ventilation has, on the 
other hand, not been apparent in our investigations. 

"Our results in regard to the influence of the chemical com- 
posHion of vitiated air (temperature and humidity effects being 


excluded) have been generally negative. In two respects, how- 
ever, our experiments suggest that some chemical constituents 
of the air of an unventilated room may be objectionable. Such 
air appears (1) to decrease the appetite of human subjects for 
food, and (2) to diminish substantially the amount of physical 
work performed under conditions of equivalent stimulation. 

"We may conclude then that the primary condition of good 
ventilation is the maintenance of a room temperature of 68 F. 
or below without the production of chilling drafts ; but that it 
is also important, on account of certain subtle but real effects 
of vitiated air upon appetite and inclination to work, to pro- 
vide for an air change sufficient to avoid a heavy concentration 
of effluvia such as was associated in our experiments with a car- 
bon dioxide content of 23 to 66 parts per 10,000." 

Except in respect to humidity at moderate and low tempera- 
tures this long quotation reenforces the conclusions set forth in 
this book and in World Power and Evolution. It brings out the 
extreme sensitiveness of human health to atmospheric condi- 
tions; it shows that temperature is undoubtedly the most im- 
portant factor; it adds experimental proof to the widespread 
opinion that as soon as the temperature rises much above 70, 
man's capacity and inclination for physical work decline and 
his susceptibility to disease increases. If high atmospheric hu- 
midity is added to high temperature, as in many tropical coun- 
tries, the harmful effects are shown to be much accentuated. 
The fact that the Ventilation Commission detected no effect of 
high temperature and humidity upon mental work seems to mean 
merely that when people are subjected to moderately adverse 
conditions for short periods amounting to less than twenty per 
cent of the time for a few weeks the physical handicaps do not 
become pronounced enough to exert a measureable influence 
upon the mind. It seems only logical to suppose that if the ad- 
verse physical conditions arising from high temperature and 


high humidity were to continue and produce their full effect, the 
mental powers would ultimately suffer. Thus even this phase of 
the Commission's work is not inconsistent with the conclusions 
of this book. In this same connection it is interesting to note that 
although the Commission made no experiments on the effect of 
variability, its report contains in several places the specific sug- 
gestion that variability may be an important but unconsidered 
factor. The only point wherein the Commission's conclusions 
radically differ from my own is in respect to humidity, a subject 
which we shall consider in the next chapter. In spite of this dis- 
crepancy the report of the Ventilation Commission, in its main 
aspects, confirms the general conclusions of this book as to the 
relatively depressing effects of tropical climates, regardless of 
specific diseases ; and as to the beneficial effects of relatively cool, 
variable climates. 



INASMUCH as there is some disagreement as to the effect of 
atmospheric moisture upon health, it will be well to examine 
the evidence carefully. On the basis of the deaths in Paris from 
1904 to 1913, Besson,* the chief of the "Service Physique et 
Meteorologique" of that city, has come to the conclusion that 
"on the whole, when the humidity increases, the mortality [from 
diseases of the respiratory organs] decreases two or three weeks 
later. ... If one examines each season separately one finds 
that this rule fails only in summer when there is no clear result, 
According to a widespread opinion humidity acts in an un- 
favorable manner upon human health. The result announced 
above cannot fail to surprise many people. One sees that an in- 
crease in the number of deaths from diseases of the respiratory 
organs is on an average preceded not by an increase but by a 
decrease in the humidity." To test this further, Besson divided 
the winter months into two groups, one with a mean relative 
humidity below 86 per cent and averaging 82.4 and the other 
above 86 per cent and averaging 89.2. He found that the deaths 
per week when relatively high or low humidity prevailed and in 

the succeeeding weeks averaged as follows : 

Advantage of 

Deaths per week high over low 

Low High humidity in per 

humidity humidity cent of low 

The same week 




One week after 




Two weeks after 




Three weeks after 




Four weeks after 




* Louis Besson: Relations Entre les Elements M6t6orologiques et la 
Mortalite. Annales des Services Techniques d'Hygiene de la Ville de Paris, 


It seems clear that during these ten years in Paris the drier 
weeks of winter, even though they were quite moist, were accom- 
panied by a slightly increased death rate from respiratory dis- 
eases and were followed in the next two weeks by a death rate 
about 6 per cent higher than that which followed the moist 
weeks. Besson ascribes part of this effect to the direction of the 
wind, but the effect of the wind must be produced largely 
through humidity and temperature. What part is played by 
temperature in the results for Paris is not clear. 

A study of my own includes temperature as well as humidity, 
and gives results almost identical with those of Besson. I used 
the deaths from pneumonia in New York City during the year 
beginning in April, 1917, and compared them with the weather 
on the day of death and on the preceding day. All the days with 
any given temperature were divided into two equal groups on the 
basis of their relative humidit}'. Here are the results for the 
7200 deaths from lobar pneumonia. Those for broncho-pneu- 
monia were somewhat similar, but much more irregular, pre- 
sumably because the number of deaths was only a third as great. 



DAY. (NEW YORK, APRIL 1, 1917, TO MARCH 31, 1918.) 

Mean temperature 20 or less 21-32 38-45 46-55 56-65 G6-70 71-75 76 or 


Low relative humidity 28.4 26.7 28.7 21.5 19.8 10.5 6.5 6.8 
High relative humidity 26.3 25.9 28.0 18.8 15.1 8.2 6.1 6.5 

Advantage of moist over 

dry 8.0% 3.1% 2.5% 14.3% 31.1% 28.0% 6.6% 4.4% 

The obvious fact here is that at all temperatures the moist 
days were better than the dry, as appears in the lower line. The 
same thing holds true whether we consider the deaths on the 


same day as the humidity or on the succeeding day. While Bes- 
son's data seem to show that dryness renders people susceptible 
to the initial attack of pneumonia which results in death after 
a fortnight more or less, the New York data suggest that when 
the disease nears its crisis a dry day may turn the balance 
toward death, whereas a moist day turns it toward life. In cold 
weather, however, this effect is slight, for when the temperature 
is below 45 the moist days in the preceding table reduce the 
death rate only 4.5 per cent on an average. At the temperatures 
of 56 to 70, on the other hand, an additional grain and a half 
of water vapor per cubic foot of space, or a difference of roughly 
20 per cent in relative humidity, is associated with a diminution 
of about 30 per cent in the death rate. This is especially im- 
portant because these are the temperatures at which our houses 
are kept, or ought to be kept, most of the year. It adds another 
to the bits of evidence which indicate that for respiratory dis- 
eases a dry climate is worse than a moist one. The opposite belief 
has perhaps become traditional largely because in dry climates 
people live out of doors. Other things being equal, it is always 
more healthful to live outdoors rather than indoors. 

In this connection it might be added that Besson's conclusions 
as to the relation of temperature to the death rate from respira- 
tory diseases agree with mine as to the similar relation to deaths 
from each of the two main types of pneumonia. At temperatures 
between freezing and 60 F. there is an almost perfectly regular 
decline in the number of deaths as the temperature rises ; then 
the decline becomes less and less marked until a minimum is 
reached at about 72. At higher temperatures a slight increase 
makes itself apparent, but does not go far because there are 
only a few days in either Paris or New York when the mean 
temperature rises much above 75. Still another investigation, 
that of Greenburg,* who studied the monthly deaths from pneu- 

* David Greenburg: Relation of Meteorological Conditions to the Preva- 
lence of Pneumonia. Journal of American Medical Association, 1919, p. 252. 


mo ilia in New York, Boston, Newark, and Providence, agrees 
with the two already cited as to the effect of both temperature 
and humidity upon pneumonia. Such close agreement makes it 
practically certain that the humidity of the air, as well as the 
temperature, is an important element in determining the death 
rate from respiratory diseases. 

The need of certainty as to the effect of atmospheric humidity 
is so great that I shall sum up a number of other examples in the 
form of a long table which the non-scientific reader can skip. 
Since the effect of humidity varies according to temperature, we 
must carefully distinguish between temperatures above and 
below the optimum of 64. At the optimum temperature in every 
one of the groups of deaths listed in section A of this table, the 
best conditions of health prevailed when the relative humidity 
averaged 70 per cent or more for day and night together. At 
higher temperatures a relative humidity which averages above 
70 per cent (for day and night together) does very decided 
harm. At the optimum temperature the effect of humidity seems 
to be at a minimum, and a humidity above 70 per cent does little 
harm. A lower humidity, although somewhat harmful, has less 
effect than at other temperatures, the increase in the death rate 
ranging from 5 to 15 per cent, according to the degree of dry- 
ness. This may be one reason why the New York Ventilation 
Commission found no clear effect of low humidity. Their main 
experiments were performed at temperatures close to the opti- 
mum. At temperatures below the optimum the effect of humidity 
upon the death rate is very clear, much more so than at the opti- 
mum. For example, at a temperature of about 40 F. a difference 
of only 10 per cent in humidity appears to produce approxi- 
mately the effect shown in section A of the following table. 



A. Increase in Monthly Death Rate Accompanying a Decrease of 10 Per Cent 

in Relative Humidity at a Temperature of 40 F. 

(1) Northeastern United States, 1900-1912 0.8% 

(2) East central United States, 1900-1912 1.3% 

(3) Dry interior of the United States, 1900-1912 2.0% 

(4) Boston (deaths after operations), 1906-1915 3.1% 

(5) Large cities of United States (whites non-contagious dis- 

eases), 1912-1915 3.3% 

(6) Large cities of United States (negroes, non-contagious dis- 

eases), 1912-1915 4.0% 

(7) British Columbia, 1914-1916 7.0% 

(8) Large cities of United States (whites, contagious diseases), 

1912-1915 9.5% 

(9) Southern France, 1901-1910 10.0% 

(10) Northern France, 1901-1910 11.0% 

(11) Northern Italy, 1899-1913 12.6% 

B. Increase in Monthly Death Rate Accompanying a Decrease of 10 Per Cent 
in Relative Humidity at All Temperatures, December-March, 1900-1914 

(12) St. Louis 0.5% 

(13) New York City 1.2% 

(14) San Francisco 3.8% 

(15) Baltimore 5.0% 

(16) Chicago 7.8% 

C. Increase in Daily Death Rate Accompanying a Decrease of 10 Per Cent 

in Relative Humidity at All Temperatures During the Influenza 

Epidemic in New York City (September-December, 1918) 

and Boston (October, 1918-April, 1919) 

NOTE. The figures in this section indicate percentages of the average daily 
change in the death rate instead of percentages of the actual deaths. Hence 
the figures are perhaps five times larger than if they were reckoned as in 
A and B. 

(17) Onset of influenza, Boston 3.0% 

(18) Onset of influenza, New York 6.9% 

(19) Deaths from influenza, Boston 11.3% 

(20) Deaths from pneumonia, New York 21.6% 

(21) Deaths from influenza, New York 26.2% 

(22) Deaths from pneumonia, Boston 8.3% 

(23) Onset of pneumonia, Boston 1.8% 


This table represents all the available mortality data except 
those already mentioned and certain others to be given shortly. 
Practically all the evidence seems to point in the same direction. 
In 21 out of the 23 sets of data in the table the moister days or 
months have an advantage over the drier. The negative figures 
for Boston, Nos. 22 and 23, may be accidental, or may mean 
that Boston's famous east winds, unlike the moist winds in most 
places, are really too damp. Taking the table as a whole, an 
increase of 10 per cent in humidity at low temperatures is corre- 
lated with an average decrease of not far from 6 per cent in the 
death rate. 

Let us now turn to quite a different investigation. In Boston 
I made a study of the number of deaths following operations 
performed in different kinds of weather. On the basis of about 
2300 deaths after operations from 1906-1915 the addition of 
a grain of moisture per cubic foot of space to the air within 
doors would have diminished the death rate as follows, provided 
the inside air thereby acquired the qualities pertaining to the 
outside air moistened by nature : 




Percentage of decrease in 
deaths for one additional 
A. Mean temperature grain of water per cubic foot 

30 or less 



. . . . 16.5% 



50-60 .... . . 




Because of the small number of deaths this table is irregular, 
but the irregularities have little significance. At temperatures 
below the optimum the death rate was higher after operations 



performed in damp weather than after those performed when the 
air was dry. This was especially true when the moist weather 
continued a day or two after the operations. At high tempera- 
tures, however, the effect of humidity is not at all the same as at 
low, as appears in Figure 15. Dry conditions are shown toward 






& 0.25 


Relative Humidiiy at 6 AH 

K> 60 SO 

Above 70'al 6 AM. 

4}-SO'at 8 AM 
61-70*ctt 8AM 
51-60'ai 8AM 

Figure 15. Post-operative Death Rate at Boston in Relation to Humidity 

and Temperature 

the left, moist toward the right. The height of the lines shows 
the number of deaths per day succeeding operations performed 
when various conditions of relative humidity prevailed at 8 a.m. 
The broken lines, A, B, and C, indicate the number of deaths in 
cool weather. Note their regular decline toward the right. High 
humidity was evidently an advantage. Now contrast the dotted 
lines with the solid line, A, indicating the effect of humidity 
when the temperature at 8 a.m. was above 70. Under such con- 
ditions, far more than in cooler weather, dry air was bad. 
Moderately moist air with a relative humidity of 50 to 60 per 
cent was better than even the moistest air at lower temperatures. 


But note how rapidly the death rate after operations performed 
in hot weather rises if high humidity is added to great heat. 
Nevertheless the evil effects of very damp hot days in Boston do 
not appear to be so bad as those of very dry hot days. This study 
of surgical operations seems to afford strong evidence of the 
extreme sensitiveness of the human body to variations in hu- 
midity as well as temperature. The fact that it gives a different 
result at temperatures above and below the optimum tends to 
establish confidence, for the results at high temperature and 
high humidity are in perfect accord with common experience and 
with the experiments carried on by such organizations as the 
New York Ventilation Commission and the laboratory of the 
American Society of Heating and Ventilating Engineers at 

In other countries as well as in France, Italy, and the United 
States, whence our data have thus far come, the statistics seem 
usually to indicate that extreme dryness is harmful to health. 
Other things being equal, the death rates appear generally to be 
higher in dry regions than in moist. For example, Lucknow and 
Cairo in dry climates have death rates far higher than Madras 
and Bombay, which are moist and tropical. Mexico City on its 
high, cool, but dry plateau, and Johannesburg and Madrid in 
somewhat similar locations, have exceptionally high death rates 
in view of their temperature and latitude. In Mexico and India 
the dry season of March, April, and May has a decidedly higher 
death rate than the succeeding wet season. This happens in spite 
of the fact that the temperature in Mexico City during May 
averages 65 and is almost ideal, while in July it averages a 
degree or two cooler and is almost equally ideal. In India, on 
the other hand, both the dry spring and the wet summer are hot, 
so that the wet season is very muggy. Yet the people heave a sigh 
of relief when the rains come, for it brings hope of a diminution 
of disease as well as of good crops. 

Let us turn to variability or storminess, another factor which 


seems to cooperate with temperature and humidity in determin- 
ing the effect of climate. This factor is especially important be- 
cause of its bearing on changes of climate and their effect on 
history. In World Power and Evolution the study of climo- 
graphs based on eight million deaths in France, Italy, and the 
United States suggests that people's sensitiveness to changes of 
temperature is almost directly proportional to the uniformity 
of their climate. For example, in San Francisco a change of 
only 7 in the mean monthly temperature (50 January, 57 
July) is associated with a change in the death rate from I6A 
per cent above normal to 11.7 per cent below, or about 4 per 
cent for every degree of temperature. At St. Paul and Minne- 
apolis a change from a mean temperature of 12 in January 
to 67 in June is accompanied by a change in the death rate 
from 5.5 per cent above normal to 6.9 below, or only 0.23 per 
cent for each degree of temperature. In the same way a differ- 
ence of about 9 C. between January and May in Naples is 
accompanied by a difference of 35.3 per cent in the death rate, 
whereas in Milan a difference of 16 C. in temperature is asso- 
ciated with a difference of only 26.8 per cent in the death rate. 
Put in another way this means that the apparent effect of a 
given change of temperature is 2.3 times as great in Naples of 
the South as in Milan of the North, and over seventeen times as 
great in San Francisco with its remarkably uniform climate as 
in St. Paul and Minneapolis with their severe winters and many 
storms at all seasons. 

In other words, where great changes of weather take place, 
people become hardened to them. The reality of this hardening 
is demonstrated again and again by the way in which north- 
erners who move to the tropics lose their power of resistance to 
even the slightest changes of temperature, but regain it after 
a few years of renewed residence in a severe climate. The relation 
between variability and the power to resist disease seems quite 
clear, but as yet there seems to be no conclusive evidence as to 


the relative importance of variations from day to day such as 
accompany storms, and of variations from season to season. The 
evidence which will now be set forth pertains to changes of 
temperature from day to day. 

In World Power and Evolution one of the most important lines 
of evidence has to do with variations of temperature from one 
day to the next in New York City. A study of about 400,000 
deaths during a period of eight years from 1877 to 1884 shows 
that when the temperature falls the death rate also falls, while 
a rise in temperature is regularly accompanied by a correspond- 
ing rise in the death rate. This happens not only in summer, 
when one would expect it, but at all seasons, including even the 
winter, when one would surely suppose that warm weather would 
be beneficial. And so it is, in the long run, but the immediate 
change toward warmth is temporarily harmful. 

In this investigation, instead of employing the absolute num- 
ber of deaths, as in previous cases, the change in the number of 
deaths from one day to the next has been used. This is done 
partly in order that the greater frequency of days with abrupt 
changes of temperature in winter than in summer may not con- 
fuse our results. It is likewise because in dealing with changes 
of temperature the natural question is whether such changes 
have any effect in changing the death rate. 

The upper part of Figure 16 illustrates another investigation 
of the same kind in respect to daily deaths from pneumonia in 
New York. The left-hand side of the diagram indicates the con- 
ditions which prevail when the mean temperature of the day of 
death is higher than that of the preceding day, while the right- 
hand side indicates that the temperature has fallen. The two 
solid lines indicate the summer relationships from April to Sep- 
tember, A being lobar pneumonia, and B broncho-pneumonia. 
The dotted lines show winter conditions, C lobar, and D broncho- 
pneumonia. The significant points about these four curves are 
as follows : 



(1) They are all essentially alike. This suggests that they all 
conform to some definite physiological law. 

(2) Every one of them is low at the two ends and high in the 

Rise of Temperature Drop of Temperature 

10* 5' 5" JO'F 






Deaths from 
Pneumonia. In 
New York. Apr 
1917 lo Mar 1918 

Deaths from 
Pneunronia and 
Inflaenza, com- 
bined during 
Epidemic of 1918 
New York 
- -Boston 

Figure 16. Relation between Deaths from Pneumonia and Influenza and 
Interdiurnal Changes of Temperature 

middle. This seems to indicate that under normal conditions such 
as prevailed in the year ending in March, 1918, patients suffer- 
ing from either form of pneumonia are less likely to die on days 
when there has been a marked change of temperature in either 


direction than on days when there is little or no change. This 
conclusion applies to both summer and winter, but is more true 
in summer than winter. Hence, for pneumonia patients, a vari- 
able climate seems better than one that is uniform. The agree- 
ment of the curves with our conclusions derived from factory 
work and with those of Campani in Italy is noteworthy. 

(3) A drop of temperature, on an average, is decidedly more 
effective than a rise in lowering the death rate. This again 
agrees with the results of our factory investigation. 

The lower part of Figure 16 shows the results of a similar 
investigation of the influenza epidemic in the latter part of 1918. 
Because of the enormous variations in the death rate I have here 
used the percentage rather than the actual number of deaths 
by which each day's death toll differed from that of the pre- 
ceding day. Both New York (solid lines) and Boston (dotted 
lines) have been included. The investigation has been broadened 
to include (1) the number of cases in which influenza (a) and 
pneumonia (b) attacked a patient, or at least, in the case of 
Boston, were reported to have done so, and (2) the number of 
deaths from influenza (c) and pneumonia (d). The significant 
points in Figure 16 are as follows : 

(1) All the lines except that for deaths from pneumonia in 
Boston (c') slope in the same way, thus indicating that a rise of 
temperature is worse than no change, and that a fall is much 
better than either. This disagrees with the preceding investiga- 
tion of normal pneumonia, but that may be simply because the 
lower part of Figure 16 includes only the winter months and 
not those of the spring when the advent of warm days would be 

(2) The average changes in the rates for all the conditions 
shown in the lower part of Figure 16 amount to an increase of 
14.1 per cent in the deaths and illnesses on days with a strong 
rise of temperature and 3.4 per cent on days with little or no 
change, whereas on days with a strong drop of temperature the 


change takes the form of a drop of 18.4 per cent. This means 
that for all the days when the temperature was markedly dif- 
ferent from that of the preceding days, no matter whether it was 
higher or lower, there was an average drop of 2.2 per cent in the 
rates of disease and death against a rise of 3.4 per cent on the 
days of comparatively uniform weather. In other words, here, 
just as in normal pneumonia, the variable weather had an ad- 
vantage over the uniform weather. This conclusion is quite con- 
trary to the usual ideas, but it is supported by many other bits 
of evidence. 

One such bit is found in the following data as to the average 
number of deaths per day in Boston hospitals after surgical 
operations, when specified changes of temperature took place 
between the day of an operation and the succeeding day. 

Interdiurnal change of temperature 

Daily deaths 
December to 

Daily deaths 
March to 

Changes of 9 F. or more in either direction 
Change of 4 to 8 in either direction . 
Change of 3 or less in either direction . 



The first column suggests that in winter the changes of tem- 
perature are too severe in Boston, so that days with only a little 
change have an advantage of about 4 per cent over the d&ys 
with a violent change. From March to November, however, the 
conditions are quite different: operations performed on days 
with the smallest changes are followed by 41 per cent more 
deaths than are those performed when the temperature changed 
most strongly from the day of the operation to the next day. 
Thus for the year as a whole the variable weather displays a 
distinct advantage just as in New York. 

The net result of our studies thus far is the conclusion that 
temperature, humidity, and variability all play important parts 


in determining variations in health and mortality from day to 
day, month to month, season to season, and year to year. For 
each climatic factor there appears to be a distinct optimum or 
most favorable condition, but this varies considerably in re- 
sponse to differences in the other factors. Thus the optimum 
temperature in dry weather is not the same as in wet, and pre- 
sumably is not the same in variable weather as in that which is 
uniform. The high level of the optimum temperature which we 
found in California may possibly be due in part to the uniformity 
of the weather. Again, a degree of humidity which is highly 
favorable at a temperature of 50 F. may work severe harm at 
80, just as a degree of variability which is highly beneficial in 
warm weather may be too extreme in the midst of a cold winter. 
In the rest of this chapter I shall describe certain investiga- 
tions in which the three climatic factors of temperature, hu- 
midity, and variability are analyzed in reference to the influenza 
epidemic in 1918. The investigation of influenza was carried out 
by a Committee on the Atmosphere and Man appointed by the 
National Research Council of the United States. A mathe- 
matical method known as partial correlation coefficients was em- 
ployed. This method has the remarkable quality of picking out 
and isolating the effect of any one among a number of factors 
as in an experiment. In the present case the Committee set itself 
the completion, or at least the extension, of a task already begun 
by Professor Pearl of Johns Hopkins University. The task was 
to ascertain whether any environmental conditions were re- 
sponsible for the great differences in the mortality of the influ- 
enza epidemic of 1918 from one city to another. During the ten 
weeks of the main epidemic Philadelphia, for example, had a 
death rate from influenza and the resultant pneumonia four times 
as great as that of Milwaukee, while the rate in Pittsburgh was 
twice as great as in the neighboring and similar city of Cleve- 
land. Before the committee's investigation was finished the fol- 
lowing twenty-two factors had been examined : 


A. Factors of human environment (demography). 

1. Age (proportion of inhabitants of various ages). 

2. Sex (number of females per hundred males). 

3. Density of the population (persons per acre within city). 

4. Rate of growth from 1900 to 1910. 

B. Factors of geographical position. 

5. Distance from Boston, where the epidemic began. 

6. Longitude. 

7. Latitude. 

C. Physiological factors; normal death rates in 1916, 1916, and 1917 from: 

8. All causes. 

9. Pulmonary tuberculosis. 

10. Organic diseases of the heart. 

11. Nephritis and acute B right's disease. 

12. Typhoid fever. 

13. Cancer and other malignant tumors. 

D. Racial factors. 

14. Percentage of negroes, 1920. 

15. Percentage of foreign born, 1920 

E. Industrial factor. 

16. Percentage of population engaged in manufacturing, 1919. 

F. Climatic factors. 

17. Mean temperature for day and night. 

18. Change of mean temperature from one day to the next. 

19. Absolute humidity (weight of water vapor per cubic foot of space). 

20. Relative humidity, or percentage of possible water vapor. 

21. Weather a combination of Nos. 17-20. 

22. Climatic energy as denned in this book. 

Directly or indirectly these twenty-two factors embrace most 
of the conditions which may have been effective in causing 
people's power of resistance to the epidemic to vary from city to 
city. Sanitation and medical practice fail to appear in the list 
because their degree of excellence cannot easily be expressed in 
figures. But the death rate from typhoid fever is generally sup- 
posed to be an unusually good measure of sanitary efficiency, 
while other death rates are in most places a fairly good index 
of the excellence of the medical service. Almost the only im- 


portant field which the factors do not cover is that of variations 
in the disease-bringing bacteria so far as such variations are 
due to causes not included in our table. When all these various 
factors are investigated by means of the most exact and delicate 
mathematical method yet known, the only one which shows any 
conclusive causal relation to the destructiveness of this particu- 
lar epidemic is the weather. 

In the work which ultimately led to this conclusion, the Com- 
mittee on the Atmosphere and Man took the death rate from 
influenza and pneumonia during the ten weeks succeeding the 
outbreak of the epidemic in each of thirty-six large cities in the 
United States. These ten weeks cover the first and, in most 
places, much the more important outbreak. The committee also 
obtained data as to the temperature, relative humidity, absolute 
humidity, and change of temperature from one day to the next. 
The weather data were tabulated for periods of ten days be- 
ginning seventy days before the onset of the epidemic and con- 
tinuing fifty days thereafter. Previous to the thirtieth day 
before the epidemic there is evidence of no real relationship be- 
tween any weather condition and the destructiveness of the in- 
fluenza. During the thirty days just before the onset of the 
epidemic, however, the temperature and especially the absolute, 
as distinguished from the relative humidity show a distinct rela- 
tion to the succeeding death rate. This means that if the weather 
was warm during the month before the influenza reached a city, 
the death rate was high; if the amount of moisture in the air 
was great, the conditions were still worse. At Boston, for ex- 
ample, from the twentieth to the eleventh day before the epi- 
demic the temperature was higher than during the corresponding 
period in any other cities except New Orleans, New York, and 
Los Angeles. This was natural, for the epidemic broke out in Bos- 
ton earlier than elsewhere. In places like St. Paul, Toledo, and 
Grand Rapids, the cool and fairly dry autumn weather which 
prevailed for a month before the epidemic apparently gave peo- 


pie a certain degree of stored-up vigor which stood them in good 
stead and lessened the ravages of the disease. If the tempera- 
ture was variable, as in Cleveland, Columbus, and Richmond, 
and especially if it fell during the ten days after the onset of 
the epidemic, the death rate was lower than where the contrary 
conditions prevailed. On the other hand, high relative humidity 
during the ten days before the onset was associated with a 
relatively high death rate. Cambridge, New Haven, and New 
Orleans suffered most in this respect. The dampness perhaps 
made it easy for the bacteria to be transmitted. Droplets of 
water in the air may act as carriers of the bacteria, or may pre- 
serve their virility. 

From the tenth to the thirtieth days after the onset of the 
epidemic the virulence of the bacteria was apparently so great 
that the state of the weather made no difference in the death 
rate. At any rate there is no evidence that the immediate weather 
conditions had any effect in overcoming the sudden and sweeping 
character of the infection. After the thirtieth day, however, 
there came another change, and the apparent effects of tempera- 
ture and absolute humidity again rose high. This was the time 
when in most places the disease reached its maximum and began 
to decline. At that time cool and moderately dry weather once 
more was associated with a low death rate. This does not neces- 
sarily mean that cold weather is favorable at the time of an 
epidemic. In fact, quite the contrary may be the case, for very 
low temperature may be as bad as high. Labrador suffered 
greatly in the epidemic of 1918. 

Having reached the conclusion that atmospheric conditions 
influenced the severity of the epidemic, the next step was to find 
a numerical expression for the weather by combining the tem- 
perature, humidity, and variability according to their apparent 
importance. When this had been done, the method of partial 
correlations was used to compare the weather with the severity 
of the epidemic and with all the other factors which showed any 


sign of being important, namely, deaths from tuberculosis, 
deaths from all causes, deaths from heart diseases, and climatic 
energy. The weather proved to be the only one whose correlation 
coefficient was more than four times the probable error, and 
hence large enough to be significant. The final partial correla- 
tion coefficient, when the four other factors named above were 
held constant, that is eliminated, amounts to 0.57. This is 7.6 
times the probable error, which means that there is only one 
chance in hundreds of millions that we are being misled by acci- 
dental agreements between the weather and the death rate. 

"Thus," to quote the report of the committee, "the statistical 
fact is clear. The weather, which means primarily the weather 
just before the onset of the epidemic and at or just after the 
climax, is the one factor thus far investigated which shows a 
clear, pronounced, and persistent relation to the destructiveness 
of the epidemic. This does not mean that the weather was in 
any sense a cause of the epidemic. It is even possible that the 
weather may be related to the epidemic only indirectly, as is the 
case with the death rate from heart disease, although no factor 
capable of producing this result has yet been suggested. Even 
if the weather is a causal factor in producing variations in the 
virulence of the epidemic, there is no reason to think that it is 
the only factor. If the degree of relationship between two vari- 
ables is proportional to the square of the correlation coefficient, 
as is sometimes held, the weather, even if it is a direct a;^ent, may 
be responsible for no more than a third of the variations from 
city to city. Nor do our high correlation coefficients mean that 
the weather had anything to do with setting the date of the epi- 
demic or with determining the severity of the 1918 epidemic 
compared with other epidemics. Neither do they prove anything 
as to the effect of the weather in other countries, although else- 
where a relationship similar to that found in the United States 
seems probable. For instance, the British government estimates 
that in India the death rate from the epidemic was about six 


times as great as in the United States, while scanty reports from 
other tropical countries indicate a similar excessive mortality. 
The one thing which seems clear from the present investigation 
is that the weather is the one factor whose apparent relation- 
ship to the epidemic is not seriously reduced or modified when 
other conditions are held constant. 

"The results of this investigation should be qualified in still 
another respect. It is not necessary to suppose that other epi- 
demics will show exactly the same relationships as the epidemic 
of 1918, even though they may be strongly influenced by the 
weather. In the first place, the epidemic of 1918 was so peculiar 
in its virulence, its rapid dissemination, its fatality for persons 
in the prime of life, and in other respects, that it may well have 
been peculiar in its climatic relationships. In the second place, 
the epidemic occurred at a season when the approach of cold 
weather normally exerts a strong stimulating effect in the 
United States. It is well known that from August to October or 
even November the death rate normally declines. The epidemic 
seems to have reflected this condition. Just so far as the weather 
approached the conditions which prevail at the time when the 
autumn mortality is lowest, the ravages of the epidemic were 
checked. At some other, colder season, relatively low tempera- 
ture and low humidity might be as harmful as high temperature 
and high humidity appear to have been in September, October, 
and November, 1918. As a matter of fact, the epidemic of Feb- 
ruary and March, 1919, shows only a small positive correlation 
between the monthly death rate and the temperature. Other con- 
ditions, perhaps other conditions of weather, were then domi- 
nant; or possibly some cities were too cold while others were 
too warm, a condition which would make the use of correlation 
coefficients impracticable. 

"Finally, even if the weather should prove to be an important 
factor in causing variations in the virulence of influenza, we still 
have little evidence as to how its effects are produced. Presum- 


ably the weather gives to the human being more or less power of 
resistance to disease. But it is not improbable that the weather 
also has an important effect upon the vigor, reproductive rate, 
or transmission of the disease-bringing bacteria." 


THIS chapter deals with two investigations of the relation 
between health and the weather. They seem to me the most 
conclusive evidence yet available along this line because the 
various weather elements are more clearly separated than in 
most cases, and because there is no danger of confusing the 
effects of different seasons. The first investigation pertains to 
the weather day by day, and is by far the most extensive in 
which daily data have been employed. It represents a coopera- 
tive effort carried on by the Committee on the Atmosphere and 
Man of the National Research Council of the United States and 
the Metropolitan and New York Life Insurance companies. In 
addition to the author those most closely concerned in planning 
the work were Dr. J. Arthur Harris of the Carnegie Institution's 
laboratory at Cold Spring Harbor and Dr. L. I. Dublin of the 
Metropolitan Life Insurance Company, but many suggestions 
were received from others. The results appear to be fairly con- 
clusive as to mean temperature and changes of temperature, 
but are inconclusive as to relative humidity. 

In order to obtain an adequate series of daily mortality data 
the Committee was obliged to go back to the years 1882 to 1888 
in New York City. At that time and for a few years previous 
the actual day of death was recorded and the facts were sum- 
marized by days and published in the annual reports of the New 
York Board of Health. This highly valuable record has not 
since been equalled either in New York or elsewhere, so far as 
I am aware. The Committee used three sets of mortality data: 


(1) deaths of children under five years of age; (2) deaths of 
persons over five years of age; (3) deaths from pneumonia. In 
order to avoid errors due to the growth of population and the 
improvement in medical practice, each year was treated as a 
separate unit, and each category of deaths was reduced to per- 
centages of the average number of deaths per day in that par- 
ticular year. 

For the phase of the investigation here under discussion, the 
method of partial correlation coefficients was employed. For the 
layman it may be well to repeat that by this method the 
effects of different factors can be separated as in an experiment. 
In order to avoid periods when the temperature is sometimes 
above and sometimes below the optimum, the months of De- 
cember to March were chosen. This is also advisable because 
the effect of the various climatic elements in winter is less under- 
stood than their effect in summer. One aim of the work was to 
eliminate the effect of the seasons and determine whether a 
mere departure of the weather elements from the normal for any 
special month has any effect. Accordingly, in preparing the data 
for the correlation coefficients each month was treated as a sepa- 
rate unit, and the departures of all kinds were reckoned from the 
averages for December, January, and so forth. This made it 
possible to ascertain almost beyond question that the weather 
day by day causes small variations in health which are super- 
posed upon the large seasonal variations. 

The Committee used three elements of the weather: (1) the 
mean daily temperature; (2) the interdiurnal change of mean 
temperature from one day to the next; and (3) the mean daily 
relative humidity. In nature the effects of these three elements 
are inextricably mixed, but the method of partial correlation 
sorts them out. The results of this sorting appear in Figure 17. 
The day marked zero is the day on which a given condition of 
weather occurs. The weather elements on each such day have 
been compared with the deaths on that day and on each of the 

Mean Temp&raiurc l,,k r-diun?al Change of 

Cha/jyes of Tempemlure iu..{ TciY)peTCllUTe 

Rdalive Hiunidity hdil totwl^ Temp and Retatwe uniid% Comtant 

Relative Humidity 

Temperature and Changes of 
Temperature hriUl Ccmalank 

C <a 






odhs over 
ve Ycur5 

G R, 



: 17. 

Correlation between Weather Elements and Daily Deaths in New York City, 
December to March, 1882-1886 


fourteen succeeding days. The lengths of the bars in Figure 17 
indicate the size of the partial correlation coefficients. The three 
diagrams on the left show the relation between mean temperature 
and the deaths in our three categories when the interdiurnal 
change of temperature and the relative humidity are held con- 
stant and thus eliminated. The three central diagrams show 
similar coefficients for changes of temperature when mean tem- 
perature and relative humidity are held constant ; while the right- 
hand set apply to relative humidity when mean temperature and 
changes of temperature are held constant. 

Where the bars of Figure 17 lie above the central line, the 
coefficients are positive ; that is, a high condition of the weather, 
such as high humidity or high temperature, is associated with 
a high death rate. Where the bars are below this central line the 
reverse is the case, high temperature, for example, being asso- 
ciated with few deaths. But note that in studying changes of 
temperature our purpose is not to discover the effect of a small 
change compared with that of a large change regardless of 
whether the temperature rises or falls. It is to discover whether 
the effects of a rise and of a fall are the same or different. Ac- 
cordingly, the average condition has been counted as that in 
which there is no change of temperature from one day to the 
next ; a rise of temperature has been given a plus sign and a fall 
a negative sign. Hence in the central column of Figure 17 a bar 
above the line means that a high death rate is associated with a 
rise of temperature, while a bar below the line means that the 
death rate is high when the temperature falls. 

The degree of significance of the bars in Figure 17 may be 
judged from the shading. Where the bars are lightly shaded 
their length is less than three times the probable error. This 
means that they have little or no significance. When the light 
shading reaches its greatest length, that is, when the coefficient 
is three times the probable error, there is one chance in twenty- 
two that a bar of this length would be produced accidentally 


even if our two sets of figures have no real relation. Suppose for 
a moment that the death rate and the relative humidity have no 
real relationship. Nevertheless, with figures the size of those 
here used we should accidentally get a correlation of 0.075 (three 
times the probable error) once in every twenty-two correlations. 
The three diagrams on the right of Figure 17 depict forty-five 
correlation coefficients. Hence mere chance would be likely to give 
us two that rise as high as 0.075. What we actually find is two 
which rise a little above that level. 

The areas marked by diagonals indicate values between three 
and four times the probable error. Now, the likelihood that a 
coefficient of any particular size will be produced accidentally 
decreases very rapidly as the coefficients become larger. Thus 
while there is one chance in twenty-two that a coefficient will be 
three times the probable error, there is only one chance in one 
hundred forty-two that it will be four times the probable error. 
Among the ninety coefficients in the first and second columns of 
Figure 17 mere chance would not be likely to give more than one 
coefficient rising to the outer limit of the diagonals, but as a 
matter of fact we have eleven. If the coefficient is five times the 
probable error there is only one chance in 1341 that it is due 
to accident arid not to a real relationship ; if six times, only one 
in 19,300; seven, 427,000; eight, 14,700,000. For all practical 
purposes a coefficient eight times the probable error gives full 
certainty of a relationship of some sort. 

In general we may say that in Figure 17, or any similar dia- 
gram, the conditions that suggest a relationship are (1) coeffi- 
cients more than three times the probable error; (2) a con- 
siderable series of coefficients all having the same sign and hence 
all falling either above or below the central line; (3) a series of 
coefficients which systematically change from high values to low 
or from positive to negative, or vice versa. The conditions which 
are generally agreed to amount to practical proof of a relation- 
ship are ( 1 ) individual coefficients which rise to at least six times 


the probable error; (2) several successive coefficients rising to 
at least four times the probable error; (3) a considerable series 
of coefficients which systematically and persistently change their 
values in some orderly sequence such as from three or four times 
the probable error on the plus side to an equal value on the 
negative side. All three types are represented in Figure 17. 

We are now ready to interpret that Figure. Bear in mind that 
the length of the columns indicates the degree of relationship 
between deaths and the weather elements, and has nothing to do 
with the actual number of deaths. Remember also that when we 
speak of temperature in what follows, we mean temperature after 
the effects of relative humidity and interdiurnal changes of tem- 
perature have been eliminated by means of partial correlations. 
In similar fashion relative humidity and changes of temperature 
mean those two factors individually after the other two have 
been eliminated. To begin in the upper left-hand corner, the posi- 
tion of the bar for day above the central line in diagram A 
indicates that during the 726 days from December to March in 
the six years under discussion, high temperature on any par- 
ticular day tended to be accompanied by a large number of 
deaths of children under five years of age on that same day. The 
small size of the bar, however, indicates that this relationship 
is too small to be considered seriously. On the other hand, the 
temperature on any given day had a pronounced relation to the 
deaths during the next three days, as appears in the heavy black 
shading of days 1 to 3. High temperature was systematically 
followed by a low death rate, and low temperature by a high 
death rate. Inasmuch as we are dealing with only a single day's 
weather, and inasmuch as the largest coefficient ( 0.167) is 
seven times the probable error, the total effect of the mean tem- 
perature for all days on the deaths among children must be 
great. On the fourth day after a given temperature, however, 
it has practically disappeared. 

Diagram B suggests that the reaction of older persons to the 


outside temperature is similar to that of little children. Curi- 
ously enough, however, on the day when a given temperature 
occurs the effect is stronger than among the children, while on 
succeeding days the opposite effect is weaker and is somewhat 
more delayed. Probably the immediate harmful effect of high 
winter temperature arises from the fact that when the outer air 
is unusually warm for the season, our houses are likely to be 
kept too warm, especially on the first day of such warmth. On 
the other hand, when unusually cold days arrive, many houses 
which have been too warm become cooler and that is helpful, but 
soon the fires are pushed and the old condition of hot, stuffy 
rooms returns. 

In diagram C, showing the relationship between the mean tem- 
perature and the deaths from pneumonia, the most important 
feature is the fairly regular decline from a moderately high 
level on the left to a low level on the right. This apparently 
means that temperatures which are high for the season tend to 
cause death among pneumonia patients, but have a good effect 
in preventing other people from contracting the disease, so that 
the death rate from pneumonia falls off after about two weeks. 
Further comment on these first three diagrams is unnecessary. 
They confirm the results obtained in other ways, and show that 
the temperature of even a single day plays an appreciable and 
measurable part in determining the general health of the com- 

Look now at the middle column of Figure 17. This depicts the 
relationship between the death rate and the change of tempera- 
ture from one day to the next when the mean temperature and 
the relative humidity are both eliminated by means of partial cor- 
relations. Among children less than five years old, as appears at 
the top, a rise of temperature tends strongly to cause many 
deaths on the day when it occurs and on the succeeding day, 
while a drop acts in the opposite fashion. So strong is this effect 
that the largest partial correlation coefficient (0.202) is 8.4 


times the probable error. Inasmuch as there is scarcely one 
chance in one hundred million that so large a coefficient should 
be accidentally obtained, we may be practically certain that 
changes of temperature from one day to the next (regardless of 
the mean temperature) exert an important effect upon the health 
of young children. The suddenness with which this effect comes 
to an end is noteworthy. The portion of diagram D from the 
third to the fourteenth day is typical of the coefficients obtained 
when there is no relationship between two sets of phenomena. 

Diagram E indicates that among older people changes of 
temperature from day to day have almost the same effect as 
among children, a rise being harmful and a drop beneficial. In 
this case, however, the relationship is not so marked as among 
the children, the delay is greater, and there is a reaction on the 
fifth day. Thus the harm done by a rise of temperature, or the 
good done by a fall, is partly neutralized by effects of the oppo- 
site kind a few days later, but the neutralization is only partial, 
as appears from the greater size of the shaded areas above than 
below the zero line. 

Pneumonia patients (diagram F) present another case where 
effects of opposite types occur at different times. People suffer- 
ing from this disease are probably harmed somewhat by a rise 
of temperature on the very day when it happens, and are simi- 
larly helped by a fall, but these effects are too slight to be sig- 
nificant. Two days after a given change of temperature, on the 
contrary, the pneumonia patients show a distinct benefit if the 
change has been toward warmer conditions ; they are harmed by 
a change in the opposite direction. This occurs regardless of 
whether the actual mean temperature is high or low, for that 
factor has been eliminated by our partial correlations, as has 
relative humidity. The changes themselves appear to be the 
effective agent. But how about the relatively high positive corre- 
lation on the eleventh day in diagram F? There is about one 
chance in one hundred and fifty that this is due to accident, 


whereas there is only one in about fifty thousand that the larger 
coefficient of the second day is accidental. Nevertheless, the posi- 
tive correlation on the eleventh day may be significant. If so, it 
presumably means that a rise of temperature is accompanied by 
conditions favorable to the development of pneumonia, so that 
an unusually large number of people die about eleven days after- 
ward. Here again we appear to have a curious contradiction 
between the effect of relatively high temperature and of the 
change toward such a temperature. This contrast appears so 
constantly and consistently that its reality can scarcely be 

One of the clearest and most convincing features of this in- 
vestigation of daily changes of temperature is its unequivocal 
character. In all three diagrams (D, E, and F) the high coeffi- 
cients are either higher or more numerous than in the corre- 
sponding diagrams for mean temperature (A, B, and C). This 
agrees with several other lines of evidence, such as the sensitive- 
ness of people in monotonous climates, in suggesting that varia- 
bility of temperature not only from season to season but from 
day to day may be almost as important as the mean temperature 
itself. Such slight evidence as is yet available also suggests that 
variability in other respects such as sunshine, rainfall, moisture, 
and wind may have an appreciable effect upon health. The em- 
phasis thus given to variability as a distinct factor, apart from 
the conditions which vary, is of much significance in connection 
with changes of climate and the relation of climate to the dis- 
tribution of civilization. It confirms the conclusions derived from 
our study of factories, general death rates, influenza, pneu- 
monia, and operations, and is itself confirmed by strong evidence 
which is yet to come. 

Turning now to relative humidity, we find that diagram G is 
completely negative. During the years in question the relative 
humidity of the air had no appreciable effect upon the health 
of children under five years old in New York. This is true even 


when the effects of mean temperature and changes of tempera- 
ture are eliminated. Among older people (diagram H) the same 
is true so far as any immediate effect is concerned, for days 
to 6 have irregular and insignificant coefficients. From the sixth 
to the fourteenth day after any given condition of relative hu- 
midity, however, there is a slight but persistent positive correla- 
tion every day. On two days this rises to almost four times the 
probable error. This suggests that in winter high humidity may 
possibly be favorable to the contraction of diseases from which 
people die a week or two later. A similar suggestion in respect 
to influenza has already been discussed. The pneumonia diagram 
(I), however, has a different aspect. None of its coefficients are 
large enough to be significant, but the fact that the first seven 
are all positive gives a hint that high relative humidity may 
have a slightly unfavorable effect upon pneumonia patients. 

It is most perplexing to find that different sets of data give 
different indications as to the relation between atmospheric 
humidity and health. The present investigation with its almost 
negative results, but with a slight suggestion that damp air 
facilitates the transmission of harmful micro-organisms, agrees 
with the experiments of the New York Ventilation Commission, 
and with the results obtained by the Committee on the Atmos- 
phere and Man in its work on influenza. Opposed to this are the 
results of what seem to be equally reliable investigations per- 
taining to deaths after operations, to the death rate from pneu- 
monia by months as set forth by Greenburg, to Besson's inquiry 
into the weekly death rate in Paris, and to the monthly death 
rate where millions of people were studied as described in World 
Power and Evolution. Moreover, a new investigation, shortly to 
be described, points even more strongly toward atmospheric 
humidity as an important agent in promoting health. A possible 
explanation of this apparent contradiction may be that humid- 
ity affects people in two ways, directly through the skin, nerves, 
and lungs ; and indirectly through minute organisms that bear 


disease. The disease-bearing organisms being very short lived, 
are quickly influenced by variations in atmospheric moisture. 
Hence a day or two of unusually high relative humidity may be 
enough to give them an opportunity to produce disease. Man, on 
the other hand, may be influenced more slowly so that the bene- 
ficial effect of moisture upon him becomes apparent only when 
he is subjected to moderately moist conditions for some time. 
Thus relatively long oscillations in health may arise through the 
effect of atmospheric moisture upon man, and short oscillation* 
through the effect upon the bringers of disease, and the two may 
easily be of opposite character. 

We now come to what seems to me a most conclusive study as 
to the general effect of the weather upon health. In order to gain 
a comprehensive view of the variations in this effect from place 
to place and likewise from season to season, I have made a fresh 
investigation of the deaths each month from 1900 to 1915 in 
thirty-three cities of the United States. Every city with over 
100,000 population in 1910 has been used so far as mortality 
data are available. Each city and each month of the year has 
been treated as a separate unit, the Januaries, Februaries, and 
so on being divided into two equal groups on the basis of each of 
the following climatic factors : 

(1) Mean daily temperature. 

(2) Mean daily relative humidity (average of 8 a.m. and 

(3) Variability or storminess (number of storms whose 
centers passed within two hundred miles of the given city, allow- 
ing double weight to those within one hundred miles). 

(4) Wind (total number of miles per month). Five cities 

Data for the wind were investigated only at New York, Balti- 
more, Chicago, St. Louis, and San Francisco. The Chicago data 
are doubtful because the growth of the city appears gradually 


to have cut off the wind from the Weather Bureau Station and 
caused an apparent decline in windiness. 

An example will show how the data were used. The eight warm- 
est Januaries in New York averaged 6.0 F. warmer than the 
eight coldest, and had fewer deaths by 0.6 per cent. In February 
the excess of temperature in the eight warmest months amounted 
to 6.5 and their death rate was 4.1 per cent less than that of 
the cooler months. In March the corresponding figures were 
6.4 and 9.7 per cent; in April 3.8 and 4.5 per cent; in May, 
on the contrary, an excess of 3.5 in temperature was accom- 
panied by a death rate 1.5 per cent greater in the warm months 
than in the cool months, while in July, although the eight warm 
months averaged only 2.8 above the eight cooler months, the 
excess in their death rate rose to 14.2 per cent. 

The use of this method brings out many interesting facts on 
which we cannot now dwell. It eliminates entirely all complica- 
tions due to the seasons, for each month stands by itself and can 
be compared with any other month. It likewise shows nothing as 
to the general effect of the seasonal variations of either weather 
or mortality. It merely shows how the departures of any par- 
ticular climatic factor from the normal for that particular 
month affect the death rate. Boston, for example, is thus found 
to be benefited in summer by the coolness of its damp east winds ; 
dampness without coolness is the bane of New Haven in summer ; 
New York, by reason partly of its great size and partly of its 
fine climate, is unusually regular in its responses to the weather, 
but for some unexplained and possibly accidental reason is 
averse to storms in midsummer as well as in midwinter. Although 
Baltimore is hot in summer, it suffers little harm from humidity 
even when that factor runs high. Baltimore is likewise benefited 
at all seasons if it has more than its usual allowance of storms, 
while Boston, being far north, normally has so many storms that 
it is better off during the less stormy months except in summer. 
Chicago, on the other hand, is benefited by storms except during 













the coldest months ; it is likewise benefited by high relative hu- 
midity except in the autumn, but curiously enough it is not bene- 
fited by high temperature in winter, perhaps because the warm 
months experience dry southwest winds, bare ground, and dust. 
Somewhat the same is true in Pittsburgh and Denver. Cleveland 
and San Francisco have climates of such a type that departures 
from the normal produce relatively little effect, whereas in cities 
like St. Paul and Minneapolis in the north and St. Louis and 
Cincinnati farther south the effects are much greater. In 
southerly places like Nashville and Memphis the effect of de- 
partures from the normal weather is especially great. Presum- 
ably it is still greater in the far south, but Atlanta is the only 
other southern city for which data are available. 

In Figure 18 (a and b) the thirty-three cities have been com- 
bined into geographical groups. Each city is weighted according 
to its population as follows : 100,000 to 200,000 = 1 ; 200,000 
to 400,000^2; 400,000 to 1,000,000 = 3; 1,000,000 to 
2,000,000 = 4 ; over 2,000,000 = 5. The curved lines indicate 
the extent to which the death rates in the eight warmer, moister, 
or stormier Januaries, Februaries, and so forth, from 1900 to 
1915 differed from the corresponding death rates in the eight 
cooler, drier, and less stormy Januaries and other months. The 
figures in the scales beside the diagrams indicate departures in 
percentages of the normals. The normals are the estimated num- 
bers of deaths that each place would have experienced per month 
in any given year if the number of deaths changed regularly in 
response to the growth of the city and the improvements in medi- 
cal practice without regard to weather, seasons, epidemics, and 
so forth. The method of getting the normals is explained in 
World Power and Evolution. In Figure 18 and the other figures 
of the same kind all the curves have been smoothed by the 

a + 2b + c 


which is a common way of eliminating the confusing minor ir- 
regularities which arise because of the small number of years 
for which data are available. In the figure the heavily shaded 
areas mean that the months with relatively high temperature, 
high humidity, high storminess, or high winds had lower death 
rates than the months in which the weather factors stood lower. 
For example New York, Philadelphia, and New Haven form a 
group of cities lying within a distance of about one hundred and 
fifty miles and having similar climates in spite of individual 
idiosyncrasies. In the first column of Figure 18, diagram B 
shows that in these cities the months of January, February, and 
especially March are too cold, for in each month the death rate 
in the eight warmest years was from 3 to 5 per cent lower than 
in the eight coldest, as appears from the dark shading. In April 
the average temperature was about right, for the curve crosses 
the zero line ; in that month the bad effect produced by weather 
that is a little too cool is balanced by the corresponding effect 
of high temperature during the same month. As summer ad- 
vances the warm months begin to have a disadvantage, as is 
indicated by the dotted shading. The eight warmer Julies had an 
average death rate about 6 per cent greater than that of the 
cooler Julies even in the smoothed curve ; in the unsmoothed 
curve this rises to 10.4. Inasmuch as the eight warmest Julies 
averaged only about 3 warmer than the coolest eight, each 
degree of excessive temperature raised the death rate more than 
3 per cent. 

Passing on to the second column of Figure 18 it appears that 
high relative humidity is beneficial to New York and its neigh- 
bors throughout the winter, and especially in April when an 
excess of 6 per cent in relative humidity is accompanied by a 
diminution of 6 per cent in the death rate. During the three 
summer months the highest humidities do harm, the smoothed 
maximum excess of deaths being 4 per cent while the unsmoothed 
figures are 5.8 per cent accompanying an excess of 6.4 per cent 


in the relative humidity. The duration of the period when hu- 
midity is harmful is short. During the autumn and early winter 
the nearness of the curve to the zero line indicates that it makes 
little difference whether those months are relatively dry or 
moist, perhaps because the general conditions of health are so 
good that people can resist extremes which might harm them 
at less favorable seasons. Nevertheless, the damper rather than 
the drier months were the best. 

In the third column of Figure 18 the storms of the New York 
group of cities appear to have had less influence than either the 
temperature or the humidity. In the late winter and spring the 
more stormy months were the most healthful; in summer the 
less stormy ones had a very slight advantage, too small to be 
significant ; the autumn again was like the late winter, while 
November and December were like June and July. This particu- 
lar curve happens to be one where the effect of storms is at a 
minimum. The most important thing about it is that the dark 
shading is much more extensive than the light, which means 
that on the whole the stormiest months were times of better 
health than those that were less stormy. 

In the right-hand column of Figure 18, where the effect of the 
wind is shown, the upper diagram is based only on New York. 
It is very symmetrical, and indicates that in winter high winds 
are accompanied by a high death rate, while in summer they are 
accompanied by a low death rate. 

The question at once arises whether the four types of curves 
in Figure 18 really represent the effect of the individual climatic 
factors or whether each curve is compounded of the effects of 
all four factors. For example, are high winds really favorable 
in summer, or do they merely appear to be so because they are 
accompanied by low temperature or low humidity or some other 
favorable condition? The answer is found in Figure 19. The solid 
curves there are the same as those which we have just been 
examining for the New York group of cities in Figure 18, but 



are plotted on a larger vertical scale. The dotted lines are the 
same curves corrected to allow for the other climatic factors. 
In making the corrections it was assumed that temperature is 
the most important climatic factor, and is followed by humidity, 


5 Temperature 

Relative Humidity 






o Wind New York 



Figure 19. Correction for Effect of Other Climatic 

storms, and wind in this order, for this is what is commonly 
supposed, and it is supported by the investigation here de- 
scribed. The method of making the corrections was as follows : 
Knowing how much the temperature and the death rate in the 
moister months differed from those in the drier months, it was 


easy to determine how much effect a given difference of tempera- 
ture produces. Since we know the difference in temperature be- 
tween the moister and drier months, it is possible to make 
allowance for this difference month by month and thereby elimi- 
nate from the humidity curve the effect of temperature. When 
the humidity curve had thus been corrected, the storm curve was 
corrected in the same way on the basis not only of the tempera- 
ture curve but of the corrected humidity curve. Next the humid- 
ity curve was corrected to allow for the effect of storms, and the 
temperature curve to allow for the effect of both storms and 
humidity. Finally, the wind curve was corrected to allow for 
variations in all three of the other factors. The result was the 
dotted lines in Figure 19. At the top of the diagram the cor- 
rected and uncorrected lines showing the effect of temperature 
upon the death rate are practically alike. The next pair of lines, 
those for humidity, are almost alike, but allowance for the other 
factors seems slightly to reduce the importance of humidity in 
the spring and raise it in summer. In the third pair of lines the 
corrections seem to lower the general level a trifle, thus making 
it appear that storms are a bit more beneficial than appeared at 
first sight. Finally, the corrected and uncorrected curves for the 
winds are completely different. The good effect in summer has 
practically disappeared in the corrected curve. If the data for 
the wind had been available from New Haven and Philadelphia, 
as well as New York, the smoothing of the wind curve might pos- 
sibly have been still more complete. As things now stand, the cor- 
rections seem to indicate that in Figure 18, in spite of minor 
details due to other factors, the apparent effects of temperature, 
humidity, and storms represent approximately the real effects, 
and would represent them still more closely if a larger number 
of cities were averaged together as will be done in Figure 20. 
As for the wind, it may be that high winds in winter have some 
direct effect in raising the death rate, but in summer practically 
all of their effect appears to arise from the conditions of tern- 


perature, humidity, and storms, or variability which accompany 

Let us return now to Figure 18. In the left-hand column the 
groups of cities east of the Mississippi behave almost as one 
would expect. Except for Rochester and Buffalo (D), which 
appear to be practically never too hot, all the diagrams are 
heavily shaded in winter and lightly shaded in summer, thus 
indicating that the winters from Tennessee and northern 
Georgia to Minneapolis and Boston are too cold and the sum- 
mers too hot for the best health. In the center of this area, to be 
sure, group E (Cleveland, Toledo, and Detroit), group F 
(Pittsburgh, Columbus, and Indianapolis), and group G (At- 
lanta, Nashville, and Memphis), show a curious depression in 
summer, as if the harmful effect of hot weather was somehow 
inhibited, perhaps because the hot winds are dry so that the bad 
effects of high humidity are mitigated when the temperature 
rises. West of the Mississippi all of the groups (K to N) suggest 
that while hot summer weather is generally bad except on the 
cool Pacific coast, unusually warm winter weather is also often 
harmful. This is presumably because the warm months are gen- 
erally dry ; and our monthly data seem to show that dryness 
is almost always harmful in cold weather. 

That this last statement is true seems to be abundantly veri- 
fied by the second column in Figure 18. Here there is no such 
equal distribution of heavy and light shading as in the diagrams 
showing the effect of temperature. On the contrary, almost every 
individual diagram displays a greater area of heavy shading 
than of light, and some of the diagrams such as C, G, and K have 
practically no light shading. In general the amount of heavy 
shading, that is, the good effect of atmospheric moisture, in- 
creases as one goes from the moister and cooler parts of the 
country to those that are warmer and drier. It reaches a maxi- 
mum in diagram L for Denver and Spokane, the two cities in 
our list where the atmospheric moisture is least. This clearly 


means that in practically all parts of the United States, so far 
as data are available, and especially in the drier parts, the health 
of the inhabitants would be materially improved if there were 
more atmospheric moisture. This clear-cut and apparently un- 
equivocal result agrees with the study of deaths set forth in 
World Power and Evolution, and with the study of the death 
rate after operations. The contrast between these three lines of 
evidence, on the one hand, and the results of our investigation of 
daily deaths in New York, together with the work of the Ventila- 
tion Commission, on the other, is the reason for our suggestion 
that humidity has two diverse and opposed effects. It seems to 
be beneficial in its direct effect, except at temperatures above 
the optimum, and harmful in its indirect effect through bacteria. 

Much of what has been said of atmospheric moisture is like- 
wise true of storms, as appears in the third column of Figure 18. 
Notice how largely the heavy shading predominates. Note also 
that it is scarce in northern groups of cities such as B, H, 
and M, but increases as one goes southward until in groups G, 
J, and especially C practically every month of the year shows 
a lower death rate when storms are relatively abundant than 
when they are few. Here, just as in the case of humidity, the 
regions which have few storms, like those which have little at- 
mospheric moisture, give heavily shaded diagrams because an 
increase in the number of storms is an advantage to health at 
practically all seasons. But places like Boston, which are exposed 
not only to many storms but to strong oceanic winds, may get 
too many storms in the winter. 

The question of the effect of storminess is so important that 
I have prepared Figure 20 to show what happens when stormy 
periods last several months. The upper diagram in each case 
shows the conditions when the storms of a given month are com- 
pared with the deaths of that month. In the second diagram the 
months of the sixteen years used in our study have been grouped 
into halves according to the number of storms not only in the 


month when deaths occurred, but in the preceding month. In the 
lower diagram the storminess of three consecutive months has 
been compared with the deaths in the third month. To begin 
with Boston, a relatively high degree of storminess lasting only 
a single month is slightly beneficial in summer and again, curi- 
ously enough, in winter, but this may be a mere accident due to 
the shortness of our record. If the stormy period lasts two months 
the good effect of storms is much increased. In fact, Boston's 
health would apparently be distinctly improved if the city could 
have frequent periods of relatively high storminess lasting two 
months during the summer, but not during the late winter. The 
lightly shaded area in the autumn is so small that it may be acci- 
dental. If the periods of storminess last three months, however, 
Boston gets too much of them and the death rate rises markedly. 
In other words, Boston seems to lie close to the fortunate level 
where it gets neither too many nor too few storms in the long 
run, although in the more extreme periods it gets too many, just 
as in milder periods it does not get enough. 

Contrast Boston with Chicago in Figure 20. A single month 
of more than the average storminess helps Chicago a good deal 
during all seasons except midwinter. But two successive months 
of unusual storminess, and especially three, do harm at prac- 
tically all seasons. In other words, an increase in storminess 
hurts Chicago more than Boston. Nevertheless, both cities evi- 
dently profit greatly by the fact that they have many storms, 
as appears when they are compared with cities farther south. 
In New York, for example, Figure 20 shows that increased 
storminess during periods of more than one month is beneficial in 
summer but not in winter, while Seattle is benefited by increased 
and prolonged storminess at practically all seasons. This simply 
means that New York, with less severe storms than Chicago or 
Boston, would profit by a mild increase in storminess. On the 
other hand, Seattle, with far less storminess than the other cities 
would be better off to have decidedly more. 


JFM A M J Jy A 6 O N D 

New Yorlt 

Figure 20. Excess or Deficiency of Deaths in Relation to 
Stormy Periods Lasting One Month (Upper Diagrams), 
Two Months (Middle), and Three Months (Lower), 


At the bottom of Figure 20 Baltimore and Washington, which 
are treated as a single unit, and Memphis on the Mississippi 
River in Tennessee present still a third type. At all seasons 
their stormiest months are the most healthful, for these cities 
lie toward the southern edge of the storm belt. They have far 
less stormy weather than New York, Chicago, and Boston, but 
more than Seattle. During the years under discussion all these 
places were especially stormy in March. They are benefited by 
prolonged periods of storminess in summer and autumn, but 
cannot stand such periods in the winter and spring. Too much 
emphasis must not be placed on the minor details of any of the 
diagrams in Figure 20, especially that of a small city like Mem- 
phis, for the number of years included in our data is small. 
Nevertheless, there seems to be little question that storminess 
has an important effect upon health. In a belt of country ex- 
tending from New York and Boston westward to Chicago, the 
beneficial effects of storminess are greatest. To the north of that 
belt increased storminess appears to have a harmful effect upon 
health; to the south the present degree of storminess is not 
enough on an average, and a higher degree regularly causes an 
improvement in health at most seasons. 

In concluding this chapter let us turn to Figure 21. Here the 
data for all of our thirty-three American cities have been com- 
bined into a single diagram. This shows the effect produced by 
an unusually high condition of any one of the four climatic fac- 
tors upon the death rate in the whole northern United States 
together with the Pacific coast. In using such a large area there 
is great opportunity for opposed conditions in different regions 
to cancel one another, but this cancellation is far from complete. 
Before we interpret Figure 21 let us consider for a moment the 
degree to which the diagrams may be the result of chance. In 
most such cases it is the custom for mathematicians to compute 
the probable error by means of a formula. Our method, however, 
whereby cities are weighted according to their population, and 



the departures are reckoned from normals which pertain to the 
year instead of the individual months, would cause such compu- 
tations to take an excessive amount of time. Accordingly I have 
calculated the data for four months exactly as in the diagrams, 
except that pure chance has been allowed to control the choice 
of months for each of the two groups of eight years into which 
the sixteen years have been divided. The smoothed results for 



Relative Humidity 



Figure 21. Net Effect of Weather in the United States 

comparison with Figure 21 are January 0.47, April 0.40, July 
0.72, October 0.79. In each of the four diagrams the extremes 
are four to seven times as great as the accidental variations thus 
obtained. This fact, together with the systematic character of 
the results, makes it practically certain that we are dealing with 
real relationships and not with accidental coincidences. 

If this be accepted, our diagrams in Figure 21 show that in 
the United States as a whole, excluding the South except in 


California, a certain amount of harm is done to health in winter 
by low temperature, but not so much as one would expect. The 
high temperatures of summer do much more harm. The effects 
of the wind seem to be very clear, but are probably due largely 
to the conditions of temperature, humidity, and storminess 
which accompany the winds. Now for the most surprising fact ; 
lack of moisture does almost as much harm to the United States 
in winter as does low temperature, while in the spring it does 
only a little less than does high temperature in summer. At all 
seasons the United States as a whole, omitting the parts for 
which we have no data, has poorer health in unusually dry 
weather than in that which is unusually moist. Almost the same 
thing is true of storms. The country is better off when stormi- 
ness is unusually abundant, except in the late fall. In Figure 21 
the average departures from the zero line, regardless of whether 
the departures are positive or negative, are as follows : tempera- 
ture 4.09 per cent, relative humidity 3.96, and storminess 3.60. 
These figures seem to represent approximately the relative im- 
portance of the three great climatic factors. Thus in spite of 
certain puzzling facts as to humidity, the general result of our 
study of health in relation to the weather is to confirm the re- 
sults of our previous study of efficiency in factories. The same 
conditions of temperature, humidity, and variability which cause 
people to work quickly or slowly in the ordinary affairs of life 
seem also to cause their health to be good or poor. 


WE are frequently told that the Riviera or southern Cali- 
fornia has an ideal climate. Florida lays claim to it m 
winter, the Alps in summer. Two of the few regions which rarely 
assert their preeminence in this respect are Boston with its east 
winds and London with its fogs. Yet in many ways they have a 
strong claim to high rank. It all depends upon what we mean by 
"ideal." For rest and recreation a warm, equable climate is 
doubtless most delightful; for a fishing or climbing trip some- 
thing quite different is desirable. For most people the really 
essential thing in life is the ordinary work of every day. Hence, 
the climate which is best for work may in the long run claim to 
be the most nearly ideal. But such climates are also the ones 
that are best for health. Hence they are the ones which people 
will ultimately choose in the largest numbers. The few disagree- 
able features at certain seasons are no worse than the shiver 
at the beginning of a cold plunge. 

On the basis of both work and health, the best climate would 
apparently be one in which the mean temperature rarely falls 
below the mental optimum of perhaps 38, or rises above the 
physical optimum of about 64. From this point of view the 
most ideal conditions would seem to be found where the tempera- 
ture for the year as a whole averages not far from 51, as at 
London, Paris, New York, and Peking. In four chief portions 
of the globe, the winter temperature averages not far from 38, 
and that of summer not far from 64. The first of these is Eng- 
land. At London the thermometer averages 38 in January and 


63 in July, while at Liverpool the figures are 39 and 60. If 
an average of 51 at all seasons were ideal, southwestern Ireland, 
with a range of from 45 to 59, and the Hebrides, from 42 
to 55, would be more ideal than London. On the continent, 
where the seasonal variation is greater than in Britain, the 
length of the relatively unfavorable periods with temperatures 
above 65 and below 38 also increases. 

A second region where the temperature conditions approach 
the ideal is the Pacific coast of the northern United States and 
southern British Columbia. Seattle, averaging 39 in January 
and 64 in July has practically the same temperature as Lon- 
don. Southward the seasonal range decreases. San Francisco, 
averaging 49 in January and 59 in September after the cool 
summer fogs have passed away, may claim in many ways to be 
ideal. Still farther south the temperatures of Los Angeles and 
San Diego, 53 or 54 in January and 69 in August, fluctuate 
about the physical optimum and would be ideal for physical ac- 
tivity if mean temperature were the only criterion. The mental 
optimum, however, is lower than the temperature of all except 
the unusually cold days, and variations from day to day are 
rare. A short distance inland the Californian climate becomes 
less favorable than on the coast, for the average in summer at 
Fresno, for example, is 82. Even though the heat is mitigated 
by low humidity, the continuance of such high temperature 
causes people to feel indisposed to activity. 

England and the Pacific coast owe their climatic excellence 
largely to the fact that ocean winds from the west blow freely 
over them. Two regions in the southern hemisphere enjoy the 
same advantage, namely, New Zealand and part of South Amer- 
ica, including southern Chili and portions of Patagonia. We are 
apt to think of these South American regions as sparsely settled 
places of little importance. This is true, for the present, but it 
is not because the climate prevents activity. The climate, to be 
sure, is a drawback, but the harmful feature is not the tempera- 


ture, but the rainfall. Plants, not man, are the chief sufferers. 
Unlike our other three regions, this part of the world has a 
deficient rainfall except in the west, and there high mountains 
hinder settlement. In spite of this, the few small portions of 
Patagonia that permit profitable agriculture are making prog- 
ress and would doubtless do so rapidly if not hampered by re- 
moteness, by the absence of railroads, and by the social handi- 
cap of their aborigines. 

It must not be inferred that the climates of Patagonia, New 
Zealand, England, and the Pacific coast of the United States 
are necessarily ideal. Mean temperature is not the only impor- 
tant factor. Among other things the relative humidity must be 
considered. The deficiency of moisture in Patagonia not only is 
disastrous economically, but, to judge from the preceding 
studies, it lessens man's energy. A similar effect is produced by 
excess of moisture, and thus harm is done in Ireland and western 
Scotland, which would otherwise be almost as fortunate as Eng- 
land. New Zealand, the central Pacific coast of North America, 
and England itself are sometimes unduly damp for long periods, 
but nevertheless enjoy a relative humidity of not far from 70 per 
cent much of the time. Other regions, however, such as the 
eastern United States and central Europe, seem to be more 
favored in this respect. 

The change of temperature from day to day, as we have seen, 
seems to be as important as relative humidity, and must accord- 
ingly be considered more fully. Its effect on human activity seems 
to be second only to that of the mean temperature of the seasons. 
The intensity and number of daily changes depend upon two 
chief factors, first, the range of temperature from the warmest 
to the coldest part of the year, and second, the number of 
cyclonic storms. Where the winters are cold and the summers 
hot, the changes from day to day are also extreme. For instance, 
in the Dakotas, where the mean temperatures of January and 
July differ by 60 F., a change of equal magnitude may take 


place in twenty-four hours. On the other hand, in a place like 
the Congo, where the difference between the coldest and warmest 
months is only three or four degrees, the days are correspond- 
ingly uniform. The whole matter is illustrated by maps in many 
physical geographies and in such publications as Bartholomew's 
Meteorological A tlas. The parts of the world where the change 
of seasons favors a highly advantageous degree of change from 
one day to the next include most of North America, but omit 
Florida, the Pacific coast of the United States, and the regions 
from the Mexican border southward. All of central and eastern 
Europe is also included except parts of Italy and Greece. A large 
area in North Africa and a small area in the south of that conti- 
nent also rank high, as do central Australia and the part of 
South America which includes central Argentina. Finally, all 
except the southern parts of Asia lie within the high area. Thus 
this particular favorable condition occurs not only in many 
regions whose climate is also good from other standpoints, but 
in a much larger number whose general climatic conditions are 
decidedly unfavorable. This is not surprising, for the beneficial 
effect of pronounced changes of temperature from day to day 
is often nullified by great heat in summer or extreme cold in 
winter. Moreover, the seasonal range of temperature forms only 
one of the two factors which determine the amount of stimulation 
derived from changes of temperature from day to day. 

The other factor is the number of cyclonic storms. By this, 
as has already been explained, we mean the ordinary storms 
which produce our changes of weather from day to day in the 
United States and Europe. Probably the storms are more im- 
portant than the range of temperature from season to season, 
for they bring rain, humidity, changes in the winds, and all sorts 
of stimulating variations. The world's stormiest region, so far 
as known, includes the Great Lakes region of the United States 
and southern Canada. Around this center there is an area of 
great storminess extending southward approximately to Mary- 


land and Kansas, and northwestward through the Dakotas to 
Alberta. Eastward it includes New England and the Maritime 
provinces, while northward it quickly disappears. To the south 
the storminess diminishes gradually, so that Florida has a 
moderate degree of variability in winter but not in summer. 
Southern California is the least stormy part of the United 
States. In Europe the very stormy regions include Britain, 
most of France, Germany, parts of Scandinavia, and the north- 
ern part of Italy, together with western Austria and the Baltic 
region. In Asia, Japan is the only place where cyclonic storms 
are at all numerous. The lands of the southern hemisphere gen- 
erally have few storms. New Zealand is the chief exception, al- 
though there they do not cause such great changes of tempera- 
ture as in America and Europe. The extreme southern tip of 
South America is likewise stormy, but its storms do not cause 
much variability. On the contrary, they give rise to a monotony 
of wind and clouds which is extremely deadening, according to 
the testimony of those who have lived in such places as Tierra 
del Fuego or the Falkland Islands. Farther north, in central 
Argentina, there is a moderate number of storms, comparable 
to those in the southern United States, and their effect is dis- 
tinctly favorable. 

We are now prepared to estimate the relative stimulating 
power of the various climates of the world. In England, for ex- 
ample, the mean temperature of the seasons and the degree of 
storminess are both highly favorable, while the seasonal changes 
are only moderate. Germany is above medium in temperature, 
and high in seasonal changes and storminess. In this respect, it 
resembles the northeastern United States and southern Canada. 
Japan is similar except that it is somewhat too warm and damp. 
The coast of British Columbia and of the neighboring states is 
highly favorable in mean temperature, and medium in storminess 
and seasonal changes. Around San Francisco, the mean tempera- 
ture is still better, but both seasonal changes and storms are 


mild. In compensation for this, however, there are frequent 
changes of temperature because fogs blow in from the ocean, 
and are quickly succeeded by the warm, bright weather which 
generally characterizes the interior. Farther south where the 
fogs cease, the conditions become less favorable from the point 
of view of the changes from one day to another, although the 
mean temperature of the seasons still remains advantageous. 

The chief defect of the climate of the California coast is that 
it is too uniformly stimulating. Perhaps the constant activity 
which it incites may be a factor in causing nervous disorders. 
When allowance is made for the fact that California's urban 
population is relatively smaller than that of states like Massa- 
chusetts and New York, insanity appears to be even more 
prevalent than in those states. Moreover, the cities of the Cali- 
fornia coast have the highest rate of suicide. In 1922 four 
California cities led the list in suicides, the number per 100,000 
population being : San Diego 47.8, Sacramento 37.9, San Fran- 
cisco 30.4, and Los Angeles 30.3, against about 15 in the eastern 
cities. Possibly these facts may be connected with the constant 
stimulation of the favorable temperature and the lack of relaxa- 
tion through variations from season to season and from day 
to day, although other factors must also play a part. The people 
of California may perhaps be likened to horses which are urged 
to the limit so that some of them become unduly tired and break 

In the same way the people of the eastern and central United 
States are more nervous and active than those of Europe but 
not necessarily more efficient because of still different climatic 
handicaps. They are alternately stimulated and relaxed by 
frequent changes from day to day, and in this are like horses 
that are well driven. In the spring and autumn, however, the 
combined effect of ideal temperature and highly invigorating 
daily changes spurs them to an astonishing degree of effort. 
Then comes the hot summer or the cold winter, either of which is 
debilitating. People do not diminish their activity at once, espe- 


ciallj in the winter. They draw on their nervous energy, and thus 
exhaust themselves. They are like horses which pull on the bit, 
and when urged a little break into a run, straining themselves by 
their extreme speed. Then they are pulled up so suddenly that 
they are thrown back on their haunches and injured. In Ger- 
many somewhat the same conditions prevail, although not to so 
great an extent. England apparently comes nearer to the ideal 
than almost any other place. The climate is stimulating at all 
times, both by reason of abundant storms and because of a 
moderate seasonal range. It never, however, reaches such ex- 
tremes as to induce the nervous tension which prevails so largely 
in the United States. 

In strong contrast to these highly favored regions are such 
places as the center of Asia, where the winters are depressingly 
cold and the summers unduly hot. The range from season to 
season is apparently helpful, but its good effects are largely 
nullified by the infrequency of storms. Day succeeds day with 
no apparent change. In the desert of Takla-Makan in Chinese 
Turkestan in the fall of 1905, 1 found that one of the most sur- 
prising features was the way in which winter came upon us 
unawares. Each morning the thermometer stood a trifle lower 
than the preceding morning, but there was never any change 
such as that which we so often experience in America when the 
first severe frost suddenly comes after a series of days as warm 
as summer. Frost at last began to prevail at night, but not until 
we found the water frozen hard in the morning did we realize that 
winter was upon us. So it goes, month after month, with deaden- 
ing monotony. Yet when a storm does come the change is often 
much more extreme than in more oceanic regions. It is frequently 
so great that its value as a stimulus is much diminished. 

Tropical regions suffer even greater disadvantages than do 
places like the center of Asia. Not only is the temperature un- 
favorably high, but there are practically no cyclonic storms 
except in portions where a few hurricanes occur each year. 


Thunder storms, to be sure, are abundant, but they rarely bring 
any important change of temperature. Moreover, the seasonal 
range from the warmest to the coldest month is generally less 
than the difference between day and night. Day after day dis- 
plays no appreciable variation from its predecessor. The uni- 
formity of the climate seems to be more deadly than its heat. 
Such uniformity, perhaps as much as the high temperature and 
high humidity, may be one of the most potent causes of the 
physical debility which affects so many white men within the 
tropics, and which manifests itself in weaknesses such as drunk- 
enness, immorality, anger, and laziness. Even in tropical high- 
lands the same deadening monotony prevails, although to a less 
degree than in the lowlands. Such monotony is perhaps the 
condition which will do most to prevent the white man from living 
there permanently for generation after generation. His general 
health may not seem to suffer, but if he works hard he is in great 
danger of breaking down nervously. The temperature of the 
highlands may be highly stimulating. There are many places 
where the mean temperature during every month in the year is 
within a few degrees of either the physical or mental optimum, 
or of their average. At Quito in Ecuador, for example, the cold- 
est month, November, averages 54.3 F., and the warmest 
months, February and September, 55. Nowhere within the 
tropics, however, are there any regions which enjoy the physical 
optimum at one season and the mental optimum at another. If 
we are justified in associating a high rate of insanity on both 
the Atlantic and Pacific coasts of the United States with the 
peculiar climatic conditions, we should expect that white men 
in tropical regions at high altitudes would suffer still more in 
the same way, or else would become inert, but no figures seem to 
be available to determine this point. 

We might proceed to discuss scores of ways in which a knowl- 
edge of the exact effects of climate may assist in the under- 
standing of historic events, or help in guiding future develop- 


ment. As a step in this direction let us construct a map of the 
world showing the degree of energy which we should expect 
among normal Europeans in various regions on the basis of cli- 
mate. This map will be based entirely on our studies of work 
among factory operatives and students, and I shall leave the 
description of it unchanged from the first edition of this book 
except for the correction of an error. Later we shall test this 
map of "climatic energy" by one of "climatic health" based on 
our studies of mortality and disease. Both maps are determined 
by (1) the mean temperature month by month, (2) the amount 
of change from one day to another, and (3) the relative humid- 
ity. The conditions which prevail at various seasons in the east- 
ern United States duplicate those of almost every portion of 
the globe. There are hot, dry days like those of the Sahara ; hot, 
damp days like those in the Amazon forests ; cold days like those 
on the great ice-sheet of Greenland, and days of almost every 
other description. At this point we must make an assumption 
which cannot be tested until vastly more data have been col- 
lected. Let us assume that the continuance of a given condition 
produces the same effect as its temporary occurrence. For ex- 
ample, in Connecticut our measurements of the effect of days 
having a mean temperature of 75 are based on occasional days 
scattered through the summers of several years. Only in rare 
cases do four or five days of such extreme temperature follow in 
succession without interruption by more moderate weather. The 
actual figures show that the first hot day does not greatly 
diminish people's energy, for the human body is able to resist 
for a while and to carry the impetus of previous good conditions 
into the first part of a bad period. After two or three days, how- 
ever, the heat takes hold on people and makes them inefficient, 
or even causes some to collapse. If such weather continued for 
months we should become somewhat accustomed to it, and the 
period of collapse would be past. Just what the rate of work 
would then be we cannot yet determine. It would almost certainly 


be slower than on the first hot day, but it would probably be 
faster than on the third or fourth. Because of this uncer- 
tainty we are obliged for the present to assume that it would 
be equal to the average of a number of first days and a much 
smaller number of second, third, fourth, and so on. Having 
made this assumption, but recognizing that it needs testing, we 
may go on to construct our map. We must remember that it is 
not supposed to be a map of the actual energy displayed by the 
people of various places, but of the energy that we should expect 
among Europeans if they lived in these places and were influ- 
enced as are the people of the eastern United States. 

In making such a map it is fortunate that the most important 
factor is also the one most carefully tabulated by climatologists, 
and for which our investigations of energy give the most un- 
equivocal results. The mean temperature for every month in 
the year is given for about 1100 stations in all parts of the 
world in Hann's Klimatologie. The third curve from the top in 
Figure 10, it will be remembered, shows the average efficiency 
which would be expected at any given temperature on the basis 
of the work of factory operatives in Connecticut and New York. 
A table inserted as an appendix to this book shows the value for 
each degree of temperature according to the centigrade scale, 
the maximum being reckoned as 100 at a temperature of 15 C. 
or 59 F. To determine the effect of mean temperature upon 
human activity we simply take from Hann the mean temperature 
of each month, and then from the table in the Appendix, or from 
the curve in Figure 10, find the corresponding relative efficiency. 
Then we add the values for all the months. If every month had 
an average temperature of 59, with a corresponding relative 
efficiency of 100, the efficiency for the place in question would 
be 1200. As a matter of fact this is never reached, but London 
stands at 1196.6, San Francisco at 1198.6, and Quito in Ecua- 
dor at 1198.9. The worst place is Massaua near the southern 
end of the Red Sea, where the figure is 1070. 


The next process in constructing a map of climatic energy is 
to determine the effect of changes of temperature from day to 
day. Unfortunately exact statistics are not available in most 
regions, and we are obliged to employ an approximation. Since 
changes from day to day depend chiefly upon the seasonal range 
of temperature and the number of storms, I have combined the 
two, giving equal weight to each, and giving the two together 
approximately one half the weight assigned to seasonal tempera- 
ture. That is, the difference between Quito and Massaua, as 
stated in the last paragraph, is 128.9. This represents the maxi- 
mum effect of the seasons, so far as the average temperature is 
concerned. The maximum effect of the seasons as far as changes 
from day to day are concerned is reckoned as 30, and the maxi- 
mum effect of storminess on the same basis is also reckoned as 
30. Since highly extreme conditions are not favorable, I have 
assumed that no seasonal change beyond 30 C., or 54 F., is of 
value, and also that changes below 7 C. (19.4 F.) or above 
23 C. (73.4 F.) are of no value. In other words, if the range 
from the mean temperature of the coldest to the warmest month 
is from below 7 C. to above 23 C., it is reckoned as having a 
value of 30, just as it would be if 7 were the lowest point 
and 23 the highest. If the range should be from 4 C. to 16 C., 
it would be reckoned as having a value of 12, while if it were 
from 20 C. to 28 C., the value would be only 3, because the 
extremely hot weather above 23 would scarcely be stimulating 
even if there were slight changes from day to day. In the same 
wav extreme storminess does not produce an effect in propor- 
tion to the number of storms. One storm may succeed another 
so rapidly that the weather ceases to have sufficient variety, and 
becomes dull and lowering all the time. This is the case at Cape 
Horn, and also in certain parts of the North American Great 
Lakes region in winter. Accordingly a storminess of 20 centers 
per year according to Kullmer's scale which means far more 
than 20 storms is reckoned as the optimum. Greater stormi- 


ness is held to have the same stimulating value as 20 centers, 
while everything lower is counted proportionally. The whole 
matter is so technical that it cannot be understood without de- 
tailed explanations. These are now unnecessary, since the very 
simple method to be described shortly gives an almost identical 
but more accurate map. 

Humidity has not been considered, because the necessary 
figures are not available. In most of the cooler parts of the 
world it would make little difference, although a few unduly 
damp places like Ireland, or excessively dry regions like Chinese 
Turkestan would be lower than now appears. The chief differ- 
ence would be in the warm portions of the world. Agra in north- 
ern India, for instance, now has a lower rank than Bombay and 
Calcutta, but if allowance were made for humidity this would 
probably be reversed, for Agra is pleasantly dry much of the 
year. The same reversal would probably occur between dry 
Khartum and wet Equatorville on the Congo. Arizona and other 
desert portions of the United States would also make a better 
appearance than on the present map. It must not be forgotten, 
however, that our data for New England show that extreme 
dryness does more harm than extreme humidity. This, however, 
does not apply to high temperatures. Under such conditions 
great humidity is undoubtedly most debilitating. Yet even when 
the air is hot, it may be too dry. In such a place as Death Valley, 
in summer with the thermometer at 100 to 135 in the shade, 
it is almost impossible to drink enough water to preserve normal 
physiological conditions. Even a brief period of physical ac- 
tivity gives rise to much discomfort, and people who stay 
through the summer are in danger of suffering permanent injury 
to health. 

Our knowledge of the effect of both extreme humidity and 
extreme dryness is unfortunately still qualitative rather than 
quantitative. Some day, however, exact figures for all the vari- 
ous climatic elements will be obtainable, and we shall construct 


a map showing the actual efficiency to be expected in every part 
of the world. It will be so accurate that the manufacturer, for 
example, who contemplates establishing a factory, will be able 
to determine the precise efficiency of labor in the different places 
which he has in mind, and can put the matter into dollars and 
cents for comparison with the cost of transportation, raw ma- 
terials, and other factors. 

Meanwhile, our map makes no claim to be more than a first 
approximation to the truth. Therefore no maps of individual 
continents are now presented, but merely a map of the world, 
Figure 22, and of the United States, Figure 34. In preparing 
these the figures for Hann's stations have been placed on the 
maps. Then a line has been drawn to include all places falling 
not more than 25 points below the possible maximum. These 
are ranked as "very high" and are shaded black. A second line 
includes places falling from 25 to 50 below the maximum, and 
the area thus delimited is ranked as "high," and shaded with 
heavy black lines. The next division, indicated by light lines, 
is ranked as "medium," and the values range from 50 to 75 below 
the maximum. The area shaded with thickly scattered spots 
includes places ranging from 75 to 115 below maximum, and is 
counted as low. The fifth division, shaded with widely scattered 
spots, is "very low," and ranges from 115 to 155. Finally, the 
hot desert areas which fall below 155 are left unshaded, but if 
humidity were considered they would probably rank as high as 
the wet parts of the tropics. 

Let us now make a similar map on the basis of health. For this 
purpose I have used the climograph for the eastern United 
States as given in World Power and Evolution. Each column and 
each horizontal line of the original climograph was plotted, 
smoothed, and prolonged to the necessary limits of temperature 
or humidity where these exceeded those actually occurring in the 
eastern United States. It was assumed that a temperature of 
100 F. and a relative humidity of 100 per cent would speedily 


cause death, and that a mean temperature of 120 for day and 
night, even with the lowest relative humidity, would ultimately be 
fatal. From the smoothed data thus prepared the departures of 
the death rate from the normal under any combination of tem- 
perature and humidity can be determined. On the basis of the 
data previously given it was assumed that the effect of variability 
is approximately equal to that of temperature or humidity. Since 
the best degree of variability seems to be about twenty-one 
storm centers per year according to Kullmer's scale, this number 
was counted as the optimum. It was assumed that places having 
this degree of storminess or more have an advantage in health 
equal to one half of that due to temperature and humidity com- 
bined. This combined effect was measured by the difference be- 
tween the two extremes of Yuma, 7.8 per cent above normal, and 
San Diego, 6.3 per cent below normal. Although equal impor- 
tance is thus assigned to temperature, humidity, and storminess 
in the United States, the importance of storms for the world 
as a whole amounts to only about one fourth that of the other 
two combined. 

Unfortunately the data as to relative humidity are scanty and 
lack uniformity. Excellent and uniform figures, however, are 
available for the United States and India, and less satisfactory 
figures for Russia and Siberia. These indicate that if complete 
data were available a map of climatic energy on the basis of the 
effect of the weather on health in the United States would 
closely resemble the one based on factory work, as may be seen 
by comparing Figures 34 and 36. Hence in the absence of good 
data as to humidity we may for the present use the map of 
climatic energy based on factory work. (Figure 22.) The simi- 
larity of this map to the Indian, Siberian, and American portions 
of the map based on our data for health and the weather in the 
United States goes far toward proving its general reliability. 

The most noticeable feature of Figure 22 is two large black 
areas of "very high" energy in the United States and southern 



Jf9 MO KO 100 %0 60 40 JtO 

AO 40 60 So 200 1W 

Figure 22. The Effect of Climate on Human Energy as Inferred from 
Work in Factories 

Canada on the one hand, and in western Europe on the other. 
Each is surrounded by a heavily shaded "high" area of large 
extent. The remaining high areas, four in number, are surpris- 
ingly limited. One lies chiefly in Japan. It is shown as extending 
into Korea, but the correctness of this is doubtful, for the 
records of storms in that region are imperfect. The second lies 
chiefly in New Zealand, but extends into Australia. The records 
of storms in this region have been published less fully than in 
Europe and America, but the general appearance of the map 
seems to be approximately correct. The third of the minor high 
areas is located in the southern part of South America. The 
records here are very imperfect, and the extent of the high area 
is doubtful. The reason for this uncertainty is not only that 


reliable records of storms are not abundant, but that the avail- 
able data do not enable us to determine how much change from 
day to day is caused by the average storm. The amount of 
change must be slight compared with that experienced under 
similar circumstances in North America and Eurasia, because 
no part of the southern end of South America is far from the 
ocean. The fourth of the minor high areas lies along the Pacific 
coast of North America. As already stated, its southern portion 
owes its character not to storms or seasonal changes, but to 
frequent breezes blowing in from the ocean. It extends only a 
short distance inland, and is too narrow to be prominent on the 
small-scale maps of this volume. 

In the far North human energy appears to decline more than 
would be expected. We know that population is scanty, and 
civilization low, but we commonly ascribe this to the difficulties 
of agriculture. Little can be demanded of people who must get 
a living by hunting and fishing. From the map, however, it ap- 
pears that even if other circumstances were favorable we should 
not look for any great achievements. This accords with the slow, 
inefficient character of the Eskimos, and of the Ostiaks and other 
inhabitants of northern Siberia. Grenfell in his book on Labora- 
dor says that the Eskimo "cannot compare with the Newfound- 
land white fisherman for perseverance and 'snap.' An Eskimo 
does not get one fish for the other's ten." This happens even 
when the Eskimo is in his native habitat, and is doing work to 
which he has been trained from childhood. Racial inheritance 
may have much to do with this, but the testimony of white men 
is that after a long stay in the Arctic they themselves lose ambi- 
tion and energy. 

At the other extreme of climate the regions within thirty de- 
grees of the equator seem to be characterized by essentially the 
conditions that we should expect. The status of the highlands is 
striking. A high degree of energy among white men would not 
be expected permanently in any of them. We are often told that 


the climate of tropical highlands is as fine as any in the world. 
Not infrequently people are urged to colonize such regions. In 
book after book we read that there is not the slightest reason 
why the white man should not live there as well as at home. I do 
not assert that this may not be possible. In fact, I strongly hope 
that some day it will come to pass. Nevertheless, our map seems 
to indicate that previous to any such desirable consummation 
we must greatly increase our knowledge of how to adapt our- 
selves to nature, and especially of how to select physical types 
which are capable of preserving their own health and raising 
children in spite of the monotonous climate. At present, while 
the white man may learn to preserve his health in tropical 
regions, he can scarcely expect to retain the vigor which he dis- 
plays in the more favored parts of Europe. 

The most unexpected feature of the map is the diminution of 
energy as one proceeds eastward from western Europe to central 
Asia. In the deserts of Turkestan and Mongolia, and especially 
in the Tibetan highland, the map should probably show lower 
conditions than are actually depicted, but as records are not 
available, the medium shading has been extended across the whole 
of the unknown area. Before making the studies here described 
I should have said that a man in Siberia could be as efficient as 
in far western Russia in the same latitude. Yet the Baltic Prov- 
inces are very high in climatic energy, while eastward there is a 
steady decline until only medium conditions are reached. The 
reason is readily apparent. In the first place, the Siberian winter 
is colder and longer than that of the region near the Baltic Sea. 
More important than this, however, is the decline in storminess 
as one passes eastward across Russia into Siberia. The cyclonic 
centers of low pressure, which constitute storms, are either 
broken up when they approach Asia in winter, or else swing out 
toward the sea to avoid the great area of high barometric pres- 
sure which lies over the continent during the cold season. Hence, 
during midwinter the far interior is characterized by clear and 


extremely cold weather, not hard to bear, but steadily benumb- 
ing. In the spring and autumn, on the other hand, storms are 
fairly frequent, and are often of most terrific intensity. The 
burans, as they are called, are even worse than our western 
blizzards, which are the same thing under another name. They 
destroy cattle and horses by the thousand, and human beings 
often perish within a hundred yards of their houses. Only when 
the burans are at an end and the milder storms of the late spring 
and summer prevail does Siberia enjoy a highly stimulating 

The conditions just described afford an interesting commen- 
tary on the common idea that the plains of Siberia are to be the 
scene of a wonderful development of European civilization 
during the next few centuries. I formerly shared this opinion, 
but have now been obliged to modify it. While this chapter was 
being written I spoke of this change of opinion to a Russian 
friend who has come to America for the sake of greater freedom. 
"Yes," he said, "that is just what the exiles say. I have many 
friends who are exiles. When they are sent to Siberia they take 
books with them and expect to do much work in writing and 
along other lines. Some plan to carry on linguistic studies, and 
some to make various other kinds of scientific investigations, but 
they almost never do it. They say that at first they begin to 
work with great vigor, but after a year or two their energy de- 
clines. They have the desire to work, but do not seem able to do 
so. They attribute this to being so far from home, and to the 
lack of stimulating contact with civilization. I think there may 
be more to it than that, for they seem to lose their energy." 

Nansen, in his fine book, Through Siberia: The Land of the 
Future, emphasizes this point. He frequently speaks of the slow- 
ness and inertia which he encountered. Here per acre the Sibe- 
rians raise far smaller crops than the Norwegians, and the main 
reason assigned by Nansen is lack of care, forethought, and 
energy in cultivating and fertilizing the soil. "There is no hurry 


here," he says, "Siberia is still a country that has a super- 
abundance of time, as of everything else ; they may think them- 
selves lucky for having so far escaped the nervous stress that 
we know too well in Europe." He also quotes Rodishev, one of 
the most enlightened members of the Duma, who sums up his 
impressions of a journey in Siberia with the statement that the 
Siberians are "a people without enterprise or initiative." Yet 
the vast body of Russians in Siberia consists of pioneers who 
voluntarily went to the new country. The mere fact that they 
broke old ties and made the hard journey into the wilderness 
bespeaks more than the usual degree of energy and initiative. 
Similar people in the United States and Canada display great 
activity ; in Siberia the climate seems to damp their vigor. 

All this suggests that the old Russian autocracy accomplished 
its purpose more fully than it realized. It not only exiled many 
of its most thoughtful and active people, but sent them to a 
place where not only do the isolation and hardships diminish 
their power, but where nature insidiously accomplishes exactly 
the kind of repression that the authorities desire. From the 
standpoint of climate,, without respect to the many other factors 
which may cause quite other results, the relative positions of 
Russia and Siberia do not seem likely to change. Both, we may 
rightly hope, are destined to advance far beyond their present 
position, but while there is reason to think that western Russia 
may approach the standard of western Europe, Siberia suffers 
from a handicap which may never let her overtake the Baltic 
regions on the west of the great northern republic. 

Turning to China, we find that the summers are often debili- 
tatingly hot, with a steady, damp heat that is apt to be trying. 
The winters, on the other hand, are by no means so long as in 
Siberia, nor so severe. Yet they are far worse than in western 
Europe, and as bad as in any part of the United States. Cold 
waves often sweep down from the north, and are so severe that 
instead of being stimulants, they are depressing in regions like 


Peking. In the south, however, they are beneficial. Everywhere 
cyclonic storms are rare, so that there is no stimulus of great 
importance from that source. This is one of the chief reasons 
why China does not stand high on the energy map. The northern 
parts of the country are more favored than those in the south or 
in the far interior, but the difference is not great. Indeed, the 
uniformity of all parts is surprising. The disadvantages of high 
temperature in the south are balanced by those of low in the 
north. If China were part of a smaller continent her nearness to 
the moderating influence of the sea would help her much more 
than is now the case. All through the winter she is under the 
benumbing control of the vast continent to the west, which not 
only sends out severe cold waves, but prevents the passage of 
storms. Japan, on the contrary, does not suffer so much in this 
way. Extremes of temperature are 'milder than in China, and 
stimulating storms are frequent. Her greatest drawback is the 
long period of hot, damp weather in summer. Nevertheless she 
stands high. Here we must bring our review of the map of cli- 
matic energy to a close. We shall come back to it again when 
we have studied the distribution of civilization. 


DOUBTLESS the reader has already noticed the striking 
resemblance between the distribution of climatic energy 
and of civilization. Look again at Figure 22 and see how the 
black areas agree with the places of highest culture. In view of 
this it seems advisable to construct a map of civilization to serve 
as a standard of reference. Only two methods appear feasible. 
One is by statistics ; the other on the basis of opinion. Both pre- 
sent grave difficulties. The statistical method will ultimately 
prove far the better, but it may not be practicable for centuries. 
For a fair estimate of the position of a country we need accurate 
statistics of education, morality, industry, inventions, scientific 
and artistic skill, wealth, pauperism, charity, crime, and many 
other aspects of human life which will readily suggest them- 
selves. No reliable figures for many of these things have ever 
been gathered in any part of the world ; no statistics for any of 
them have ever been gathered in many countries. Statistically 
it is almost impossible to compare Afghanistan, for example, 
with Kamchatka. Even where accurate statistics are available, 
the methods of compiling them are often so diverse as to make 
comparisons misleading. We may know exactly how many 
people are arrested and convicted for theft in half a dozen 
countries, but in one country the police may be so inefficient that 
few criminals are apprehended, while in another practically 
every thief may be caught. Thus the better may easily appear 
the worse. The only way to use statistics at present seems to be 
as a check upon the other method. We can select some country so 


extensive that its various parts differ decidedly, but sufficiently 
homogeneous so that the figures for all portions are comparable. 
Since the United States meets these conditions better than any 
other country we shall examine its statistics in several cases, and 
shall use them as a test of a map prepared on the basis of opinion. 

For a map of the civilization of the entire world we must rely 
on the opinion of well-informed persons, but we shall find that 
this agrees closely with the indications of statistics. The value 
of a map based on personal opinion depends partly on our defi- 
nition of civilization and partly on our confidence in the judg- 
ment of the persons in question. Even the best and broadest ex- 
perience does not eliminate personal or racial bias. Therefore, 
the only safe course is to obtain the opinions of many people 
belonging to different races and ruled by different ideals. Ac- 
cordingly, in the autumn of 1913, I asked over two hundred 
people in twenty-seven countries to help in preparing a map. 
Most fortunately this was before the great war broke out. Good 
feeling prevailed everywhere, and among men of sound judg- 
ment there was perhaps as little racial prejudice as at any time 
during the course of history. This is especially important 
because similar conditions may not prevail again for years. 

The persons whose assistance was asked were selected for 
various reasons. The larger number were geographers whose 
first duty is to know all parts of the world. Ethnologists in con- 
siderable numbers were included for the same reason, but they 
responded less freely than the geographers. Historians, diplo- 
mats, colonial officials, travelers, missionaries, editors, educa- 
tors, and business men were all included. The only criterion was 
that each person should possess an extensive knowledge of the 
world through personal knowledge, or, in a few cases, through 
reading. Some were selected because of knowledge of special 
regions not well known to most people and only reached by ex- 
tensive travel. To all these many kinds of people, numbering 213 
in all, I sent the following letter : 


"May I ask your cooperation in the preparation of a map 
showing the distribution of the higher elements of civilization 
throughout the world? My purpose is to prepare a map which 
shall show the distribution of those characteristics which are 
generally recognized as of the highest value. I mean by this the 
power of initiative, the capacity for formulating new ideas and 
for carrying them into effect, the power of self-control, high 
standards of honesty and morality, the power to lead and to 
control other races, the capacity for disseminating ideas, and 
other similar qualities which will readily suggest themselves. 
These qualities find expression in high ideals, respect for law, 
inventiveness, ability to develop philosophical systems, stability 
and honesty of government, a highly developed system of educa- 
tion, the capacity to dominate the less civilized parts of the 
world, and the ability to carry out far-reaching enterprises 
covering long periods of time and great areas of the earth's 

"In preparing such a map it is evident that statistics may 
afford much assistance, but they need to be supplemented. They 
touch only upon material things in most cases, and none are 
available for a large part of the world. Therefore, our best 
resource is the personal opinion of competent judges. Accord- 
ingly, I am asking a hundred geographers, anthropologists, and 
other persons of wide knowledge, whether they are willing to 
take the time to divide the regions indicated in the accompanying 
list into ten groups according to the criteria mentioned above. 
Group 10 will include regions of the very highest character, 
that is, those where the greatest number of valuable qualities 
are found in high degree. Group 1 will include those which are 
lowest in these respects. On the basis of this grouping I shall 
determine the average position of each region and shall prepare 
a map accordingly. 

"The purpose of such a map is threefold. In the first place, 
it will prove intrinsically interesting to a large number of 


people, and is likely to arouse considerable discussion. In the 
second place, in all geographical, historical, sociological, and 
economic discussions it seems to me that we need a clearer, 
stronger emphasis upon human character, that is, upon the 
mental and moral qualities which dominate the civilization of 
the various nations. If this is so, it is highly important, in the 
third place, that we should determine much more fully than has 
yet been the case how far various moral and mental qualities are 
influenced by physical environment, race, historical develop- 
ment, biological variations, and other causes. In order to deter- 
mine these things we need a map which shall serve at least ap- 
proximately as a standard of reference. In discussing the 
influence of such things as racial character, differences of reli- 
gion, social institutions, modern means of communication, the 
form of the land, the relation of land and sea, variations of 
climate and the like, we shall be able to gain much light by com- 
paring their distribution with that of human character as it 
now exists according to a consensus of expert opinion. 

"The matter can best be illustrated by outlining a specific 
purpose to which I mean at once to apply the proposed map. 
[Here follows a brief description of the map of human energy 
on the basis of factory work.] 

"I recognize that those to whom this letter is sent will say at 
once that they are not sufficiently familiar with all parts of the 
world, and that they have no means of distinguishing between 
different parts of China, for example, or between the different 
portions of equatorial Africa. This is certainly true, but it must 
be remembered that the classification is very rough. It is only 
desired that the one hundred and eighty-five names on the en- 
closed list be divided into ten groups, no group to contain less 
than fifteen names or more than twenty-one, and each preferably 
to contain eighteen or nineteen. It may not be easy to determine 
whether all of the divisions of France, for example, fall in the 
first group, but it is perfectly evident that none of them will 


fall in the fifth or lower. The chief thing is to place them as 
nearly as possible in their proper group according to one's own 
personal opinion. A given region may properly fall in the fifth 
group, but the purpose of this classification will not be defeated 
if it is placed in either the fourth, fifth, or sixth, for when the 
opinions of one hundred persons are averaged, individual idio- 
syncrasies will disappear. In view of the varying degrees to 
which each individual is familiar with the different regions of 
the world, I should be glad if each contributor would underline 
the names of regions with which he is well acquainted either by 
travel or reading, and would place question marks after the 
names of regions as to which his knowledge is especially deficient. 
Names not underlined or questioned will be considered as inter- 
mediate. The three grades of familiarity thus indicated will be 
weighted in the ratios of 3, 2, 1. [This has not been done, partly 
because only about half of the contributors made the division 
into three grades, and partly because the final results are not 
appreciably changed by using the unweighted values.] The 
grade of the various regions should be indicated by underlining 
or questioning the names upon the small slips mentioned below, 
but may be done upon the accompanying list if that is more con- 
venient, but in that case please be sure to return the list. For 
convenience of classification I enclose slips containing the names 
of the different divisions. These may be spread out upon a table 
and arranged in ten columns and shifted from column to column 
until an approximately satisfactory arrangement is reached. 
When thus arranged those of each column should be placed in 
the corresponding envelope of the ten here enclosed, and all may 
be mailed in the large addressed envelope. Envelope ten is for 
the highest group, and one for the lowest. 

"In making the classification, one or two points need to be 
borne in mind. In the first place, the past should not be con- 
sidered: Greece, for example, should be placed in the group 
where its condition during the past one hundred years would 


place it without reference to its ancient greatness. In the second 
place, if two races inhabit a given region, both must be con- 
sidered, and the rank of the region must depend upon the aver- 
age of the two, giving each one a weight proportional to the 
number of people. For instance, in a state such as Georgia where 
nearly half the people are negroes, they must receive half the 
weight. Still another point is that the rank of a country can 
often be determined by considering the position which its people 
take when they migrate elsewhere. For instance, the position of 
Syrians as compared with Germans when they migrate to Eng- 
land or the United States is a fair criterion as to the relative 
merits of the two races. After the first generation, however, this 
should not be applied, for the younger generation owes much of 
what it is to the new country. A final point concerns countries 
which are poor in natural resources, or which are not located in 
the main centers of the world's activity, but which are neverthe- 
less of high character. For example, so far as importance in 
the affairs of the world is concerned, England vastly outranks 
Scotland. Nevertheless, our estimate of the greatness of Eng- 
land owes much to the large number of Scotchmen who have 
gone out to build up the British Empire. Therefore, in estimat- 
ing the relative merits of Scotland and England, the matter of 
size or even of commercial importance should receive relatively 
little consideration, whereas the character and ability of the 
people as rulers, merchants, scientists, writers, and men of all 
sorts should have a predominating weight. 

"In publishing the final results I should be glad if I might 
print the names of those who have contributed, but of course this 
must be as each individual may choose. The individual lists will 
not be published, and will be treated as confidential. I judge 
that other contributors will feel, as I do, that their classifica- 
tions are of necessity so imperfect that they do not care to 
distribute them to the world at large. Hence, while the list of con- 


tributors will be published unless the contributors prefer other- 
wise, their individual opinions will be withheld. I hope, however, 
to publish a list showing the average rank of each country and 
the range of opinion between those who put it highest and those 
who put it lowest. Inasmuch as the plan here outlined depends 
upon the cooperation of many contributors, no single individual 
can in any respect be held responsible for features of the final 
map which do not meet his approval. 

*"In addition to the general list of divisions, I enclose a set 
of cards bearing the names of the states of the United States, 
and of the provinces of Canada. Would you be willing to arrange 
these in groups and place them in the proper envelopes, employ- 
ing the same method as for the larger divisions? Group 1 will 
be the states or provinces which are least progressive, or least 
influential, so far as the general character of their citizens is 
concerned, and Group 6 the highest. Each group should contain 
about ten names. The object of this you see is to make a map of 
the United States and southern Canada on the same basis as 
that of the world, but on a more minute scale. 

"The rough grouping here suggested ought not to take more 
than a few hours' time. Many days, to be sure, might be devoted 
to it, but the added accuracy thus gained would not be sufficient 
to make it worth while. If you can give the necessary time at 
your earliest convenience I shall be most grateful. If you cannot, 
would you be willing to return the list, the slips, and the en- 
velopes in order that I may ask someone else to do it in your 
place? Whether you contribute or not, I shall take pleasure in 
sending you copies of the final results. Trusting that I may hear 
from you soon, I am 

"Very truly yours, 


* This paragraph was included only in the letters sent to Americans and 
to one or two Europeans especially familiar with America. 


Replies were received from 137 persons, while others sent 
copies of their publications, so that an answer of some sort came 
from about three fourths of those addressed. The majority of 
the remaining fourth were foreigners to whom a six-page letter 
in English might appear formidable. About 90 per cent of the 
English and Americans sent replies, which is a very large pro- 
portion as such things go. I am convinced that the rest failed 
to answer chiefly because the classification required more time 
and was more difficult than I at first realized. The fact that 
classifications continued to be received for an entire year indi- 
cates that many meant to answer, but put my letter aside for a 
more convenient season which never arrived. A third of those who 
replied, fifty-four to be exact, actually made classifications, and 
all but two or three conformed so closely to the general plan 
that it has been possible to use them. The names of the con- 
tributors are given in the Appendix. I take this opportunity to 
express the warmest appreciation of their kindness in cooperat- 
ing so cordially. Not only their classifications, but their letters 
were of the highest value and in many cases contained sugges- 
tions which have been of great assistance in preparing this vol- 
ume. The same is true of many letters from persons who did not 
contribute, but who took pains to explain their reasons and to 
suggest ways in which my plan might be improved. Except where 
direct quotations are employed I have not attempted to acknowl- 
edge my indebtedness for various ideas which distinctly modify 
the tenor of these pages. This is partly because the same thought 
was often expressed by several persons, and partly because in 
many cases I cannot tell from which of several letters an idea 
was derived. Except in two instances I have also refrained from 
mentioning names, because where so many have contributed 
materials of great value, it might seem invidious to mention some 
and not others. Therefore, I can merely express my gratitude 
to all concerned. The net result of this attempt at scientific 
cooperation among men of many races and tongues leaves a 


strong impression of the spirit of fellowship and friendly help- 
fulness among men of wide interests in all portions of the world. 

The countries represented in the final classification and the 
number of contributors are as follows: Australia 1, Canada 1, 
Norway 1, Sweden 1, Netherlands 1, Russia 1, Spain 1, Portu- 
gal 1, France 2, Italy 2, Japan 3, China 3, Germany 5, Great 
Britain 7, and the United States 24. The number of Chinese and 
Japanese is particularly gratifying. The ratio between the num- 
ber of contributors and the number to whom letters were sent is 
higher among them than among any other main group except 
the Americans, as may be seen in the Appendix. It is to be re- 
gretted that no one from India or South America cooperated, 
and only one, a Russian, from the European countries east of 

The difficulty of making the classification is considerable. 
Several contributors spoke of spending an entire day upon it, 
or of taking out the slips time after time to arrange them more 
satisfactorily. Some said that they spent two entire days upon 
it. All seemed impressed by the way in which a systematic classi- 
fication of this kind brings out the weak spots in a man's knowl- 
edge. For instance, here is the way in which one contributor 
expressed himself : 

"One appreciates what a big world this is and how little one 
knows about it when he attempts such a task as you have set. 
It is a most excellent means of taking the conceit out of one." 

Another puts it in this way : 

"I must confess that it is the most difficult and one of the most 
humiliating games I have ever tried to play ! I always knew I 
was a fraud as a President of a Geographical Society, but I 
never knew before how great was my deception! The greatest 
difficulty I found lay through my ignorance of the proportion 
of the different races inhabiting a district." 


An interesting feature of the letters was the diversity of 
opinion as to the advisability of any such classification of coun- 
tries. To take the adverse opinions first, one of my best friends, 
an American geographer, put the matter very strongly : 

"I am complying with your request for a sorting of the slips 
you sent me. It is a very bad plan, and not, I think, of value. 
Indeed I am not sure that I would have done it for anyone else 
than you." 

I am glad to say that later he expressed a much less severe 
opinion. Another geographer, a Teutonic European, speaks 
most cordially in part of his letter, but comes out bluntly in 
opposition to this particular plan : 

"I am wholly unable to take part in this work. I take your 
scheme as a failure ... I guess you are here, like some other 
Americans, under the influence of a too systematizing spirit. 
It seems to me impossible to classify mankind by this simple 

Still a third, an American anthropologist, is equally uncom- 
promising : 

"Speaking frankly I do not conceive that the method you 
suggest is possible of scientific results. One must choose between 
statistics which are definite and mere judgments which are gen- 
eral. To apply the geographic method to a compound of sta- 
tistics and loose generalization may be productive of grave 

And a fourth, also an American anthropologist, expresses 
himself as follows : 

"It has been my endeavor, in my anthropological studies, to 
follow the same principles that are laid down for natural 
sciences ; and the first condition of progress is therefore to elimi- 
nate the element of subjective value; not that I wish to deny 


that there are values, but it seems to me necessary to eliminate 
the peculiar combination of the development of cultural forms 
and the intrusion of the idea of our estimate of their value, 
which has nothing to do with these forms. It seems to my mind 
that in doing so these obtain subjective values, which in them- 
selves may be the subject of interesting studies, but which do 
not give any answer to the question that you are trying to 

Another anthropologist, this time a European, at the end of 
a particularly long and suggestive letter, expresses himself thus : 

"Taking all that I have written here into consideration, I 
think that if we were going to grind all the different regions of 
your long list in the same statistical mill, and to try to compute 
an average, a highly improbable and fantastic result would be 
obtained. For my own edification I put some of your criteria 
to the test, though in a different way. I drew up a list of twelve 
characteristics of the 'highest value, 5 in which I included sense 
for beauty in literature (belles lettres) and a few others, and 
then distributed them to eleven different regions of the globe. 
My familiarity with those regions by a long sojourn or travel 
and reading, covers a lifetime. To each characteristic for each 
region I assigned a number, from 1 to 1 0. I then added the differ- 
ent values or points to try to find a ratio, which might be called 
'index of civilization.' I give it valeat quantum valere potest." 

The table possesses so many points of interest that it is in- 
serted below. At the end I have added a column showing the rank 
of the various regions according to all the contributors, as com- 
puted according to the system presently to be outlined. If the 
plan embodied in this table could be carried out on a large scale, 
it would undoubtedly be better than mine. The difficulty is that 
it requires a vast amount of work and a degree of familiarity 
with the various peoples of the earth which is found only among 


a few exceptional students who can almost be counted on the 
fingers. In course of time we may perhaps hope for a map 
based on some such minute study of human nature. Yet when it 
is before us, there is every reason to think that its general fea- 
tures, with which alone we are concerned in this book, will be 
almost identical with those of the map which we shall shortly 
consider. The reasons for this will be given later. 

One important point stands out in this table. I have given too 
little weight to the aesthetic side of human nature. In framing 
a definition of civilization I consciously thought of art in all its 
forms, but it seemed as if this were included in "the capacity 
for formulating new ideas and for carrying them into effect," 
just as science is meant to be included. Moreover, the course of 
history seems to show that every nation which rises high in other 
respects sooner or later experiences a period of high develop- 
ment in art, architecture, literature, and science. Nevertheless, 
these things should have received more specific recognition in my 

To turn now to the other side of the question, those who be- 
lieve in the utility of the plan presented in my letter naturally 
do not feel the necessity of stating their reasons. Nevertheless, 
a considerable number take pains to express approval. For in- 
stance, a widely traveled Englishman thinks that "there are 
tremendous possibilities in all such attempts." An American, 
who is familiar with most of the countries of the world, says : 
"Permit me to say how heartily I thank you for engaging in 
this enterprise. Despite any and all sympathetic or hostile criti- 
cism of such a work, or the cheap and hasty or really valuable 
appraisal likely to be made, such a scheme will be invaluable to 
all students of human progress." 

Another American, who has spent a large part of his life in 
the Orient, is of the opinion that: "It is a fascinating and very 
significant set of standards by which you have asked us to group 



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the regions. From the time I started after lunch until now, late 
in the evening, I have done nothing else. But there is more than 
fascination. There is a very deep issue involved, and I am glad 
to share in the construction of the map and the charts you are 
aiming to devise." 

One of the fairest estimates of both the advantages and dis- 
advantages of the plan is contained in a letter from "Ambassa- 
dor" Bryce, as we Americans still like to call him. With his per- 
mission I quote it in full. 

"Your idea is ingenious and interesting, and I should much 
like to see how it works out, though it seems to me, on first 
impressions, that the various factors involved are so many and 
so complex that the visual presentation you contemplate would 
need an amount of comment and explanation which would re- 
quire something like a treatise to accompany the map. You give 
one instance in the case of the state of Georgia. Another might 
be found in the other Georgia, south of the Caucasus, where 
besides the native Georgians (Karthli) there are Armenians, 
Tartars, and Russians, not to speak of minor races. Or take 
Japan. If one were to think of the educated and ruling Japanese 
and the sort of civilization they have created one would make 
a rating quite inapplicable to the ordinary Japanese. Without 
therefore doubting that by means of a map presentation very 
interesting results may be obtained, I should think that some 
modifications would be needed. 'Efficiency' is a very complex 

"If I had time I should like to try to think further about the 
scheme, and lend what aid I could to it ; but unfortunately I am 
so fully occupied by trying to finish a book for the sake of which 
I retired from the Embassy at Washington that I am, to my 
regret, unable to cooperate with you. I shall be grateful for any 
information as to the results you can send me if you have 


"P. S. [dated two weeks after the letter]. 

"I have kept the papers some weeks in order to see if I could 
help you. I have dealt with the states and provinces of the 
United States and Canada, though roughly. But I have found 
the difficulty of any adequate arrangement of the extra-Euro- 
pean world in point of efficiency impossible in respect of the 
extraordinary mixture of races. Turkey and India are nuts too 
hard to crack; ... In South America it would be easier, be- 
cause the races are really so mixed that a new race results. But 
in India they live side by side and are quite different. [Here 
follows a classification of South America.] It is quite interesting 
and makes one think. But after all it is the natural race divisions 
rather than territorial divisions that count everywhere outside 
western Europe. Even in Russia and the Balkans, race doesn't 
correspond to territory." 

These various letters give a good idea of the general opinion 
of the attempted classification. As an illustration of the diffi- 
culties to be overcome, lot me quote from an Italian contributor, 
an anthropologist: "What is the standard of these various 
civilizations? Yours, as it seems to me, is an European one, and 
this, I think, is a very limited one and cannot solve the prob- 
lems." A similar objection is expressed in a letter from an Eng- 
lish anthropologist. Quoting from my letter, he says : 

" 'The power of self-control, high standards of honesty and 
morality, . . . high ideals, respect for law' are eminently char- 
acteristic of many savage and barbarian peoples, notably the 
North American Indians, and in my opinion these latter stand 
very much higher than the average American citizen, but the 
latter lead in 'the power to lead and control other races, and 
capacity for disseminating ideas . . . inventiveness, highly 
developed systems, etc.' " 

I recognize the force of these comments. Races certainly differ 
greatly, even though they happen to dwell in the same physical 


environment. Moreover, people of a given race who live under 
the same environment may differ widely because of diversity in 
religion, government, or institutions. Furthermore, the defini- 
tion of civilization here presented does not pretend to be perfect. 
It is a European definition. Yet it is also a world-wide definition. 
The contemplative Hindu may perhaps be a higher type than 
the aggressive citizen of western Europe, but the contemplative 
type has made relatively little impression upon the world as a 
whole. If we turn to antiquity, the people who have left their 
impress are those who had this so-called European activity. The 
Greeks and Romans had it to a marked degree. The people of 
India had something of it when they wrote the Vedas. Gautama 
had it when he founded the Buddhist religion. He was contem- 
plative, but yet he had the qualities expressed in our definition. 
He was preeminently possessed of "high ideals, respect for law, 
inventiveness [in the broad, non-technical sense], ability to 
develop philosophical systems, and the capacity to dominate 
the less civilized parts of the world." He dominated through 
ideas, not force. The Jews had this same power. Such men as 
St. Paul, although not aggressive in the ruder European sense, 
were unsurpassed in "the power of initiative, the capacity for 
formulating new ideas and for carrying them into effect, the 
power of self-control, high standards of honesty and morality, 
the power to lead and control," and "the capacity for dissemi- 
nating ideas." The reason for regarding the standard here set 
forth as European is that Europe is today its great exponent. 
In the past, however, not only did Rome, Greece, Palestine, and 
even northern India possess it, but Egypt, Mesopotamia, and 
Carthage all displayed it. China, too, in her days of early great- 
ness, and the wonderful Maya people of Yucatan, the only ones 
to develop the art of writing in America, were animated by the 
same active, stirring, "European" qualities. That is why we 
remember them, but have forgotten most of their contempo- 


Granting that our definition of civilization is imperfect, but 
admitting that it includes the qualities which are of greatest 
importance in causing a nation to impress itself upon the world, 
let us now proceed to ascertain how these qualities seem to be 
distributed. The fifty contributors whose classifications could 
be used have been divided into five divisions as follows : ( 1 ) 25 
Americans, 1 of whom is a Canadian; (2) 7 British, 1 of whom 
is an Australian; (3) 6 Germanic Europeans, 4 of whom are 
Germans, 1 a Swede, and 1 a Norwegian; (4) 6 Latin Euro- 
peans, namely, 2 Frenchmen, 2 Italians, 1 Spaniard, and 1 Por- 
tuguese, with whom has been included 1 Russian because there is 
no other group in which he fits more appropriately; and (5) 
5 Asiatics, 2 of whom are Chinese and 3 Japanese. A third 
Chinese contribution was most unfortunately lost in the mail. 
The average opinion of each of these five groups is given in the 
tables in the Appendix. To obtain the final rank of each coun- 
try the averages for the five groups have again been averaged. 
Thus each race, or at least each of our five divisions, has equal 
weight in determining the figures on which will be based the 
map used in later discussions. The opinion of twenty-five 
Americans, for example, has no more weight than that of five 
Asiatics. This may seem unfair, but on the whole it seems to 
be the method best calculated to give a reliable result. All of 
us are inevitably prejudiced. The Americans put America, espe- 
cially its more backward parts, higher than is correct. The 
Asiatics put their own countries too high. By giving America 
and Asia equal weight and by dividing Europeans into three 
groups animated by different ideals and different sympathies, 
we are able largely to eliminate the effect of racial prejudice. 
The final results are summed up in Figures 23 to 28, but I shall 
defer comment upon these for the present. 

In the tables in the Appendix the countries of Europe, North 
America, and Asia have been divided into groups corresponding 
as nearly as possible to race, while those of Australia, Africa, 



and South America have each been put in a single group because 
the racial differences are either not strongly marked, as in 
Australia and South America, or are highly complicated as in 
Africa. Under each group the country whose final rank is highest 
has been placed first and the rest in consecutive order. To begin 

Figure 23. The Distribution of Civilization in Europe 

with Europe, England heads the list. It is the only region placed 
in the first rank by every contributor. Northwestern Germany, 
which includes Berlin, comes next. The Germanic Europeans 
and the Asiatics all place it in the first rank. The British almost 
invariably do so, and their opinion, 9.9, averages the same as 
that of all divisions. Among the Americans and Latins several 
place this part of Germany in the ninth class instead of the 
tenth. Hence, its average position according to them is about 


9.8. Such slight differences have little significance, for 98 per 
cent is almost as good as 100 per cent. Yet they suggest that in 
1913 people who live in other parts of the world were on the 
whole not quite so sure of the Germans as of the English. 

Following northwestern Germany we find central Germany, 
then Scotland, Denmark, Holland, and so on to northeastern 
Germany. Here for the first time we come to a region which is 
placed by one group, the Latins, in a rank lower than 9.0. Yet 
even here the Latins do not assign a rank lower than 8.5 and 
everything above this ranks as "very high." Nowhere in these 
first fourteen regions does the greatest diversity amount to more 
than one degree on our scale of ten, or 10 per cent on the scale 
of 100. This is comparatively insignificant, for it means that 
while the difference between the highest and the lowest may be 
10 per cent, each of them usually differs from the average by 
only about 5 per cent. Thus so far as numbers 1 to 14 are con- 
cerned the difference of opinion among Americans, British, Ger- 
mans, Latins, and Asiatics is almost negligible. All alike rank 
these regions very high. 

Coming to Ireland, a country which, for lack of any other 
suitable group, is placed with the Teutonic regions, we find 
much more diversity of opinion. The English, presumably be- 
cause it is part of their own empire, and the Asiatics, perhaps 
because ifc seems to them like a part of England, place it very 
high, with a rank close to 9.0. The Germans, on the other hand, 
place it at 7.0, scarcely above the medium grade, while the 
Americans and Latins place it near 8.0, which means that com- 
pared with the world as a whole they think that Ireland stands 
high, but not very high. The fact that all the Teutonic regions 
except Ireland and the Austrian Alps rank above 9.0, and that 
these two, which are partly Teutonic, stand in the high group 
near 8.0, suggests that race is a dominant factor in determining 
the status of civilization. The same suggestion is enforced when 
we note that among the Romance nations the most Teutonized 



portions stand highest. Yet the fact that innate racial differ- 
ences may be of great and even overwhelming importance, as I 
have shown in The Character of Races, by no means alters the 
fact that geographical conditions also play a highly important 

Figure 24. The Distribution of Civilization in Asia 

The Romance nations of Europe seem to possess much more 
diversity of civilization than do the Teutons. Even if Albania 
and Montenegro be omitted as not being truly Romance, the 
range is from medium in Corsica and Sardinia to high in many 
regions, and very high in parts of France and northern Italy. 
Some places, such as southeastern Spain and southern Italy, 
are rated exceptionally high by the Asiatics, although the other 
contributors agree quite closely. 



Among the Slavic nations central Russia stands at only 6.2 
in American opinion, possibly because Jewish atrocities were 
freshly in mind when the classification was made. In general there 
can be no question that the Baltic Provinces and Bohemia stand 
at the top, while southeastern and northeastern Russia are at 

Figure 25. The Distribution of Civilization in Australia 

the bottom. The European region whose rank is most doubtful 
is southern Finland. The Asiatics reduce it to about 6.6, while 
the Germans rate it at 9.4. Even in so extreme a case the average 
opinion is not open to much criticism. The final rank is about 
8.0, which puts Finland at nearly the same level as Bohemia, the 
Baltic Provinces of Russia, Ireland, and the Austrian Alps. 

It would be interesting to go through all the tables and point 
out their special features, but this must be left for the reader 



to do by himself. Only one or two additional points can be 
indicated. In Asia the first thing that strikes one is the great 
diversity of opinion as to Japan and China. This is due to the 

Figure 26. The Distribution of Civilization in Africa 

fact that the Japanese and Chinese place their own countries 
much higher than do the people of other races. This is natural. 
The surprising thing is rather that these people, with their 

Figure 27. The Distribution of Civilization in South America 


justifiable pride in a great past, do not place their own countries 
at the very top. They recognize that Europe and North Amer- 
ica have in certain ways surpassed them. Aside from Japan and 
China the agreement of the different groups as to the position 
of Asiatic countries is on the whole surprising. Only in rare 
cases does the opinion of any one group depart from the average 
opinion by more than a single degree on the scale of ten. Two of 
the few exceptions are llajputana and the Syrian Desert, both 
of which are placed exceptionally low by the Asiatics. 

In Australia and North America the diversity of opinion is 
much greater than in the older continents. It reaches a maximum 
in Canada, especially in Alberta, and in southern Greenland, 
and Iceland. In such places opinion ceases to be of any special 
value. People simply do not know what sort of conditions 
actually prevail. In Australia, likewise, the comparative newness 
of the country causes some people to overrate it and others to 
depreciate it. It has not yet reached the stable equilibrium 
which gives the world as a whole a well-defined opinion. In the 
United States there is no more diversity of opinion than in 
Europe, for that country has taken its true place among the 
nations. In Australia and Canada, on the other hand, outsiders 
who live far away and who are not racially connected with the 
inhabitants are still sceptical as to whether those countries are 
actually destined to rise as high as their people claim. 

Thus far we have drawn attention to differences of opinion 
more than to agreements. Let us now examine the matter in 
another way, which brings out the essential agreements. We will 
take North America because this is the continent as to which 
there is the greatest diversity of opinion. Figures 28 to 33 pre- 
sent a series of maps based on the average opinion of all divisions 
of contributors and on the individual opinion of each division 
respectively. Here, as in Figures 23 to 27, the rank of each 
region has been written in its proper place on the map. Then 
lines have been drawn in such a way as to separate the areas 

Figure 28. Civilization in North America, According to all Contributors 

Figure 29. Civilization in North America, According to Twenty-five Americans 


above and below 9, above and below 8, and so forth. The areas 
ranking above 9.0 have been heavily shaded, those from 8.0 to 
9.0 less heavily, and so on until places below 2.0 are almost un- 
shaded. This gives a map of civilization whose main features can 
readily be grasped. In Figure 28, which represents the average 
opinion of all groups of contributors, certain main features 
stand out prominently. They are ( 1 ) an area where civilization 
declines rapidly northward in British America; (2) a high area 
extending from east to west across the northern half of the 
United States and a narrow southern band of Canada; (3) an 
exceptionally high area in the northeastern United States from 
the Mississippi to the Atlantic Ocean; (4) a similar small, high 
area on the Pacific coast; (5) a bight of lower, but not of low, 
territory extending into Nevada; (6) a rather rapid decline 
south of the United States, which is interrupted by (7) an area 
of slight improvement in central Mexico. 

Let us now turn to Figure 29 and see how the opinion of 
Americans differs from that of the world as a whole. The general 
aspect of the two maps is the same, for every one of the seven 
features just mentioned can be detected. The older states along 
the Atlantic from New England to the northern Gulf States 
have almost identically the same rank in both maps. The chief 
difference lies in this : the Americans have a higher idea of the 
new parts of their country and of the new parts of Canada than 
have the people of other places. The3 r have a correspondingly 
low idea of the countries immediately to the south of them. In 
Central America their opinion does not differ greatly from that 
of the rest of the world, but they place the West Indies and 
Mexico relatively low. In the West Indies this is probably due in 
large measure to the fact that in order to prevent internal con- 
vulsion the United States has repeatedly intervened in Cuba 
during the brief period of self-government enjoyed by that 
country. The low estimate of Mexico probably arises from re- 
cent revolutions which at the time when the classification was 


made were producing a most unpleasant impression in the United 
States. In Europe and Asia the disorders of Cuba and Mexico 
attract relatively little attention, and the contributors to our 
classification probably thought of these countries as they were 
during their periods of long peace. 

Now let us study British opinion as expressed in Figure 30. 
One of the most noticeable things is the English opinion of the 
southern United States and especially of the southwestern 
deserts. No patriotic feelings, either conscious or unconscious, 
lead them to believe that high conditions extend to the Mexican 
boundary beyond which Americans believe that there is a great 
and sudden change. Their opinion of the Atlantic portions of 
the United States is almost identical with that of the Americans 
and of the rest of the world, and they agree with other races in 
their opinion of the regions south of the United States. They 
believe, as does almost everyone, that the Pacific coast of the 
United States stands higher than the western part of the in- 
terior, but they do not think quite so well of it as do the Ameri- 
cans, although the difference is slight. The places where their 
national pride comes into prominence are in Newfoundland and 
the Canadian Northwest. It is interesting to notice that while 
they place Newfoundland and British Columbia higher than do 
the Americans, they do not have so high an opinion of the Mari- 
time Provinces nor of Alberta, Saskatchewan, and Winnipeg. 
In the latter regions this is easily explicable. A great number of 
Americans have gone to Winnipeg, Alberta, and Saskatchewan 
during recent years, and their glowing reports have made upon 
Americans a great impression which has not yet reached Eng- 
land so strongly, and has scarcely touched the rest of the world. 
Americans perhaps think more highly of the Maritime Provinces 
than do the English because many of the most energetic Nova 
Scotians and other provincials come to the States and display 
marked ability. To cite a case which has come under my own ob- 
servation, the students from Acadia College in Nova Scotia, 

Figure 80. Distribution of Civilization in North America, According to 
Seven British Contributors 

Figure 81. Civilization in North America, According to Six Germanic Europeans 


who carry on work in the Graduate School of Yale University, 
for some years maintained a higher average grade in their 
studies than did those from any other institution. 

In the German map, Figure 31, the seven general features 
already enumerated can readily be detected, just as in the 
American and English maps. The differences are largely matters 
of detail. Such a feature as the assignment of a rank of 9.0 to 
the northern Rocky Mountain states of Idaho, Wyoming, and 
Montana, and of only 8.0 to the Dakotas, Minnesota, Nebraska, 
and Iowa is probably due to lack of familiarity with the interior 
of the continent. Why Newfoundland should stand so high is not 
evident, unless it be because the name has long been known and 
is very familiar. In the high position of Iceland racial pride is 
again evident, for the Icelanders are close akin to the Germans. 

The Romance peoples present a map (Figure 32) which again 
shows all the main features. They know, however, even less of 
the recent development of the western United States and of the 
Canadian Northwest than do the Germans. To them Alberta and 
Saskatchewan are apparently undeveloped tracts where trap- 
pers and Indians still roam, for otherwise they surely would not 
assign so low a rank as 4.4. Newfoundland for some reason is 
also placed low, only 5.2, and Greenland still lower, 3.4. On the 
other hand, just as the presence of Germanic people in Iceland 
and Greenland draws the high lines far to the northeast in the 
Germanic map, and as pride of country bulges the high lines 
to include the whole of the United States in the American map, 
so a similar racial pride causes Cuba and the Creole region of 
Louisiana to be much higher on the Latin map than on any other. 

Last come the Asiatics with a map, Figure 33, which is sur- 
prisingly like the other maps. They do not yet realize what has 
happened in the Canadian Northwest, but their opinion of 
eastern Canada and Newfoundland is close to the average. The 
place where they differ chiefly from others is in their relative 
ideas of the northern Rocky Mountain states to which they 


assign a rank of only 7.6, and of the southern states which they 
place all the way from 8.2 to 9.4. Apparently the eastern United 
States seems to them highly progressive in all parts, and they 
do not attach much importance to the presence of the negroes, 
a disadvantage which Americans themselves feel strongly. 

Taking these maps as a whole we see that they all give the 
same general impression. Where one group goes to a great 
extreme, as in Newfoundland or Greenland, some other is likely 
to go to the opposite extreme. Thus the eccentricities of judg- 
ment displayed by one race are largely counteracted by those of 
another. When all are averaged, the number of inconsistencies 
is greatly diminished. To Americans and English it ms,y seem 
that Alberta and Saskatchewan, for example, should have a rank 
higher than is here given them, but we are forced to admit that 
final judgment is not possible until these regions have been well 
populated for a generation or two. Taken as a whole Figure 28 
seems to contain no important inconsistencies, even though one 
might wish to change the rank of certain places in which he is 
particularly interested. The map represents the judgment of 
thoughtful people in many countries. If fifty other equally well- 
informed people representing an equally large number of coun- 
tries in three separate continents were chosen to make another 
classification, it is highly improbable that their map would differ 
from Figure 28 so much as this map differs from the others. 
The chances are that the two would be so nearly alike as to be 
indistinguishable. Inasmuch as thei ^e is more diversity of opinion 
in regard to North America than to any other continent, the 
maps of the others approach still more closely to a true repre- 
sentation of the opinion of thoughtful people all over the world. 
The maps are by no means perfect, for human judgment is 
fallible. Yet they at least present so close an approximation to 
the truth that we may use their general features without danger 
of error. 

During the World War and the succeeding period of hot 

Figure 32. Civilization in North America, According to Six Latin Europeans 
and One Russian 

Pigttte aa. OfttatSott i Katth toetka, According to Five Aaiati<ss 


prejudice it seemed to many people that the truth of this last 
statement was doubtful. But soberer thought today shows that 
this is by no means the case. During the war the steadfastness 
and ability with which the various races fought was almost 
directly in harmony with their position in our map of civiliza- 
tion. The Portuguese, with a rank of 70, had to be taken out of 
the main line of battle, for they could not withstand Germans, 
who rank above 95. The Austrians, Poles, Italians, and Rus- 
sians, not to mention the Asiatics and Africans came out of the 
war with less military prestige than the British, French, and 
Germans. Moreover, since the war the European countries 
shaded black in Figure 23, that is, those ranking highest in civili- 
zation, have recovered more rapidly than their neighbors of lower 
rank. France and Belgium in spite of being ravished, and Ger- 
many, in spite of her financial debacle, have strengthened their 
positions in many respects, and are pushing ahead with remark- 
able energy. Russia, on the other hand, remains in a curious 
state of suspended animation, perplexing the world by her com- 
bination of inertia and radicalism. The Soviet system is perhaps 
only nominally at the root of her troubles : the wholesale exodus 
and slaughter of the old leading classes have probably done ir- 
reparable damage whose full results may not appear for many 
years. But back of both these facts lies something in Russian 
character, something which before the war held that country 
down to a rank of from 46 to 73 in Figure 23. Spain, Italy, 
Hungary, Greece, and the rest of southern and eastern Europe 
have likewise behaved as one would expect of countries on the 
level of progress indicated by their respective positions on our 
maps of civilization. Thus, on the whole, the World War and 
its aftermath seem to confirm the value of our method of esti- 
mating human progress. 



WE now have before us maps of the world depicting the dis- 
tribution of climatic energy and of civilization. Our ulti- 
mate object is to compare them, and see whether they are caus- 
ally related. It will add to the certainty of our results, however, 
if we first apply an independent, statistical test to each of 
our two maps. Since the methods of compiling statistics vary 
greatly, our results will be most reliable if we confine ourselves 
to a single country. The United States is easily the best for this 
purpose. It possesses a large and highly varied area which tends 
to produce diversity. Its census and such organizations as life 
insurance companies furnish data compiled according to the 
same method in all parts. It is homogeneous in government and 
institutions ; equal opportunities are open to all ; and the same 
ideals and methods prevail almost everywhere. Moreover, no 
part has been devastated by war or any other great disturbance 
for nearly two generations ; the people have moved freely from 
place to place ; and there has been a constant tendency to foster 
a single type of culture. From all these points of view no other 
equal area is so nearly uniform. Racially the country is of course 
complex, but until the last few decades the great majority of the 
people have been Nordics from northwestern Europe. The vari- 
ous types have mixed to such a degree and have become so 
strongly Americanized that the native white population is every- 
where similar. The only large elements which tend strongly 
toward diversity are the negroes and the recent immigrants from 

Figure 34. Climatic Energy in the United States on the Basis of Factory- 

m 122 f~\ 117 112 107 102 97 92 87 TO T 

in m 

Figure 35. Vitality in the United States, According to Life Insurance 


Figure 36. Distribution of Climatic Health on Basis of Seasonal Variations in 

Cities, 1900-1915 

Figure 37. Civilization in the United States. The Numbers Indicate the 
Relative Rank on a Scale of 6.0 According to 23 Contributors. The 
Highest Possible Rank is 6.0 and the Lowest 1.0. This Scale is Entirely 
Independent of the One Used for the World as a Whole 


non-Teutonic countries. If these are eliminated, as they are to 
a large degree in the maps that we shall consider, essentially the 
same degree of energy and civilization ought to prevail through- 
out the country except where geographic surroundings, the 
presence of some special institution, or some other disturbing 
factor makes itself felt. 

One of the best tests of energy is vitality. We have already 
seen that the death rate varies from month to month in close 
harmony with variations in the strength of factory operatives. 
Let us now see whether there is similar geographic harmony. 
Figure 34 shows the distribution of climatic energy in the United 
States. It is a revision of Figure 22, but on a larger scale. Figure 
36 is a new map of climatic energy based on seasonal variations 
in the death rate as described in Chapters VII to IX. The general 
similarity of these two maps compiled in absolutely different 
ways is one of the strong reasons for believing that they give a 
true idea of the distribution of climatic energy. Where either one 
is heavily shaded we should expect people to be strong, vigor- 
ous, and long-lived. We might test this expectation by ordinary 
mortality data, but such data make no allowance for age nor 
for such conditions as the preponderance of unhealthful cities 
and manufacturing in the Northeast, and the natural selection of 
more vigorous types as migrants to the West. A more reliable 
test is furnished by insurance companies, for their policy holders 
are much more homogeneous than the population as a whole, and 
full allowance is made for age. A comparison between the actual 
deaths among policy holders and the deaths expected on the 
basis of standard life tables gives a good idea of the vitality of 
a community. Figure 35 shows such a comparison. It is based 
on the combined experience of three prominent life insurance 
companies whose officials have kindly placed in my hands the 
figures for hundreds of thousands of people arranged by states. 

On the map the figures indicate the actual number of deaths 
compared with the average for the whole country, which is taken 


as 100. The country has been divided into five grades corre- 
sponding to those of the energy map. The two heaviest shadings 
include regions where the mortality is distinctly less than would 
be expected from the actuarial tables. The third degree of shad- 
ing indicates conditions a little better than the average; the 
fourth, high mortality ; and the lightest, very high. The indi- 
vidual maps for each of the three companies are closely similar, 
which indicates that the general features are not due to any 
special policy of one company. Indeed, so far as the policy of 
the companies is concerned, the southern states ought to present 
a better record than the northern, for the restrictions upon the 
issuance of policies are there more rigid. For instance, one 
company entirely refuses to issue any policies in certain un- 
healthful sections of the South. Elsewhere only people engaged 
in special kinds of healthful occupations are accepted. More- 
over, in the places where risks are accepted upon the same terms 
as in the North, the medical examination is often more strict, 
especially in respect to preventable diseases such as tuberculosis. 
Various other considerations differentiate one region from 
another. For instance, in cities, especially in manufacturing 
cities, the death rate is higher than in country districts, and this 
causes New York State to be unduly high. Miners are an espe- 
cially precarious class from the standpoint of the insurance 
companies, and, therefore, are excluded by at least one of our 
three companies in some of the more remote western states, and 
are accepted only in small numbers by the others. They may 
account for the poor position of Montana, but the neighboring 
mining state of Idaho ought in that case to be equally bad. In 
all the more important respects the tendency would be to cause 
the death rate in the South to be lower than in the North, were it 
not for the disturbing element of physical weakness due to cli- 
mate. In tropical countries the figures are far worse than in the 
southern states, which is what would naturally be expected. The 
fact that sick people often go west for their health does not 


enter into the problem. Such people cannot obtain insurance. 
If they have been insured before they become sick, they are 
reckoned as belonging to the place where they lived when the 
policies were issued, and not to the place where they die. 

It would be interesting to enter into further details, but space 
does not permit. The outstanding feature of the vitality map is 
its agreement with the maps of climatic energy. As people die in 
greatest numbers during months when their energy is low, so 
they die in parts of the country where their energy would be 
expected to be diminished on account of the climate. In Figures 
34, 35, and 36 conditions are best in the North from New Eng- 
land to Kansas. Westward and southward they become less 
favorable. The decline in health is probably due in part to the 
direct physiological effects of climate, and in part to its indirect 
effects upon sanitation and other methods for the promotion of 
health. The direct and indirect effects of climate almost in- 
evitably go together, for where people's energy is great, they 
are quick to adopt new means for the prevention of disease and 
the improvement of health. Moreover, in dry, and still more 
in warm, regions it is easy to tolerate unsanitary methods of 
disposing of sewage, which thus pollutes the water supply. Yet 
all these things would apparently lose part of their importance 
were it not for the weakening effect which certain climatic condi- 
tions unquestionably produce, as is so well proved by the varia- 
tion of the death rate from month to month even in places where 
the conditions of health are most carefully looked after. Here 
we must leave the matter. The general agreement of the vitality 
map with the map of climatic energy affords strong evidence 
that the climatic map is correct. 

We are now ready to test our map of civilization in the same 
way that we have tested the map of climatic energy, that is, by 
comparing it with a map based on statistics. Strength and 
energy of character cannot easily be reduced to statistics, for 
most of the conditions and activities for which we possess exact 


data depend too much upon outside circumstances and not suf- 
ficiently upon the actual qualities of the people. Prof. Mark 
Jefferson has studied the matter carefully, and I have borrowed 
freely both from his published and unpublished work. It might 
seem as if such things as railroads, the number of letters, the 
amount of manufactures, or other similar matters might furnish 
a good clue to the intellectual capacity and cultural development 
of a people, but unfortunately this is not so. Take the case of 
railroads. Nevada has more miles of railroad in proportion both 
to the number of inhabitants and the inhabited area than any 
other state in the Union. In 1920 it had 198 miles for every 
10,000 inhabitants, while Rhode Island had only 3.3, and Massa- 
chusetts 5.5. This does not mean that Nevada is more progres- 
sive than New England. The case is like that of a desert through 
which a cowboy was riding when he met a friend. 

"What you doing here?" asked the friend. 

"Nothing," was the answer. "I'm just crossing this here desert 
because it's here." 

In the same way the railroads cross Nevada because it hap- 
pens to lie between the East and the West. If it were uninhabited, 
or peopled by savages, it would still have many railroads. 

The letters sent out by a community furnish a criterion of its 
state of civilization, but even this must be used with much cau- 
tion. A hundred letters sent by a Chicago mail-order house in 
response to orders averaging two dollars apiece are no more sig- 
nificant than a single letter from Detroit in answer to an order 
for an automobile. In this case, as in many others, a concentra- 
tion of activity in certain regions may occur without any corre- 
spondingly high ability or culture. The same is true of manu- 
factures. Doubtless, manufactures generally develop wherever a 
community rises to a high state of civilization, and the manu- 
facturing processes and all that goes with them are in turn a 
help in the development of a still higher civilization. Neverthe- 
less, the accidents of position, or the presence of natural re- 


sources are commonly supposed to cause equally progressive and 
competent communities to differ enormously in the number of 
factories. We shall examine this supposition later. 

We are forced, therefore, to turn to something more personal. 
Illiteracy and education are fairly good tests, for they depend 
largely on the immediate surroundings of each individual. Illit- 
eracy would answer the purpose excellently were it not that 
people have moved about so much in recent years. Education, 
however, is still a local matter, especially in a country like the 
United States. Each state, and often each county or town, de- 
cides for itself how much it will spend for schools, how long they 
shall be open, and how stringently attendance shall be enforced. 
Hence, the schools form an unusually delicate test of the real 
character of a community. The quality of an educational sys- 
tem cannot, indeed, be measured exactly by statistics. Never- 
theless it is fairly well indicated by certain conditions for which 
accurate statistics are available. For this purpose I have selected 
the following data for the year 1920 from the reports of the 
United States Commissioner of Education and from the census. 

1 . Percentage of young people seven to fourteen years of age 
who attend school. Colored children, those born in foreign coun- 
tries, and the children of foreign-born parents are excluded in 
order to make our data as homogeneous as possible. The per- 
centages range from 82.5 in Utah and 79.6 in Idaho to 66.9 in 
Maryland and Georgia and 65.4 in Louisiana. 

2. Percentage of young people eighteen years of age who 
graduate from a four-year course in either a public or private 
high school. Since colored and foreign-born persons are not 
distinguished from native whites in the data for high school 
graduates I have assumed that all the graduates were whites, 
and have calculated the percentage of high school graduates 
accordingly. This of course gives the South a certain advantage 
and thus compensates for the fact that in using the next two 


criteria it has been necessary to include colored pupils in one 
case and colored teachers in the other. It must be remembered, 
however, that the foreign-born population of the Northeast 
tends to lower the standards there just as do the negroes in the 
South, although not so much. The maximum percentage of high 
school graduates is reached in Maine 28.6, New Hampshire 
27.8, and Oregon 26.2. The minimum is found in Georgia 3.9 
and South Carolina 2.2, but when the allowance described above 
is made for colored people the figures become 6.6 and 4.5. 

3. Average number of days per year that each pupil in the 
public schools was actually in attendance. Good schools as a 
rule are in session fairly long, and always insist on a high degree 
of regularity in attendance. The range here is from 151.3 in 
New Jersey and 149.6 in Massachusetts, to 76.0 in South Caro- 
lina and 76.9 in Mississippi. 

4. Average salary of teachers. Unless teachers are well paid, 
the more capable young people are likely to give up teaching 
for some more lucrative and less nerve-racking occupation. Con- 
trary to general belief, teachers are paid at about the same rate 
in the Northeast and the far West, the maximum averages being 
$1282 in New Jersey and $1262 in Massachusetts compared 
with $1375 in Oregon and $1281 in Washington. In the inter- 
mediate regions the general scale of recompense falls lower, 
dropping to $1081 in Illinois, which outranks all its neighbors 
except Ohio, and to $696 in South Dakota. In the South the level 
is very low with a minimum of $426 in Georgia and only $291 
in Mississippi. 

5. The excess of young men over young women among stu- 
dents eighteen to twenty years of age. This last item may at 
first sight seem unimportant, but its significance grows as one 
studies it. In regions where the standards are low there is a 
tendency for the older boys to drop out of school, while the girls 
keep on in order to become stenographers, bookkeepers, or, espe- 
cially, teachers. Maryland and Utah have the greatest excess of 

Figure 38. Distribution of Education in the United States in 1920 on Basis of Five 
Factors Equally Weighted 

Figure 39. Percentage of Gainfully Employed Persons in the United 
States Engaged in Manufacturing, 1919 


boys over girls, and Wyoming, Montana, and the Dakotas the 
greatest excess of girls. 

In using these five criteria each one was given exactly the same 
weight, that is, the census figures for any given criterion were all 
lowered or raised proportionally, so that for each criterion the 
difference between the lowest and highest figures was the same. 
As the number of criteria was increased it was noticeable that 
the resultant map, Figure 38, became more regular. In its final 
form the map shows that in a relatively narrow belt extending 
from southern New England through New York, but not Penn- 
sylvania, and continuing to Illinois, the general conditions of 
education are excellent. The same is true in Utah and on the 
entire Pacific coast. In those places, on the whole, a large per- 
centage of the children are in school, a large proportion gradu- 
ate from the high school, the school year is long and the pupils 
are regular in attendance, the teachers are well paid, and many 
boys as well as girls continue to study after the age of eighteen. 
One or another of these conditions may break down in any indi- 
vidual state, but when all are taken together the heavily shaded 
areas of Figure 38 rank high. 

One of the most noteworthy features of Figure 38 is the rela- 
tively low position of the Dakotas and the other states in the 
western part of the Great Plains, and also the similar position 
of all the Rocky Mountain states with the exception of Utah. 
The comparatively recent settlement of some of these states 
explains the situation in part, but Washington is almost as new 
as the Dakotas or New Mexico and yet stands in the first rank. 
The sparsity of population is another factor which hinders 
education. Utah, however, has a population decidedly more 
sparse than that of the Dakotas and Wyoming, but ranks 126 
where they rank from 113 to 119. Its density of population is 
scarcely greater than that of New Mexico, whose rank is 110. 
The relatively poor conditions in the Dakotas and Wyoming 
find a partial explanation in the fact that the population is more 


completely agricultural than in almost any other part of the 
United States. There are no large cities and even villages are 
comparatively scarce or small. The great majority of the people 
live scattered over the vast plain, each family on its own quarter 
section. Hence, the children are obliged to go long distances to 
school. Muddy roads often make this difficult in the spring, 
while the severe storms of winter are an even greater obstacle. 
In spite of this, the Dakotas stand at the top in the literacy of 
their people, so that the school system must be fairly efficient. 

In New Mexico quite the contrary conditions prevail. A part 
of the people, to be sure, live on widely scattered ranches where 
the children cannot go to school. By far the larger number, how- 
ever, live in compact settlements where the houses are grouped 
in a comparatively small area because of the necessity for using 
a common water supply for irrigation, or else because of mining 
industries. Under such conditions, schools can be maintained 
more easily than on huge, townless plains like those of the Dako- 
tas. The same conditions prevail in Utah and Nevada, and to 
a less extent in Idaho, Wyoming, and Montana. Nevada's rank 
of 117 may be less creditable than South Dakota's of 114. Yet 
the fact remains that the Dakotas are lower than would be ex- 
pected, while Utah is surprisingly high. 

The proud position of Utah is presumably the result of Mor- 
monism. The leaders of that faith have had the wisdom to insist 
on a thorough system of schools, and have obliged the children 
to attend them. The "Gentiles" have in self-defense been forced 
to do equally well, and the result has been admirable. Whatever 
one may think of Mormonism as a religious belief, it must be 
credited with having accomplished a remarkable work in spread- 
ing a moderate degree of education almost universally among 
the people of Utah. Without its influence, the rank of Utah 
would probably be about 118, that is, between Colorado (119), 
on one side, and Nevada (117), on the other. I emphasize this 
because it shows how clearly our maps reflect the influence of 


any peculiar condition. Manifest^, the distribution of education 
throughout most of the United States does not depend upon the 
influence of any particular institution, for essentially the same 
institutions prevail everywhere. Yet in the map of education, 
Utah is conspicuous because it is strongly influenced by a unique 
American institution which is limited to one small area. 

Another factor which would be expected to bear an important 
part in determining the distribution of education is the presence 
of the negro. Doubtless this has a pronounced effect, for an in- 
ferior race inevitably retards a higher. Yet the map indicates 
that other factors are equally important. Not only is education 
at a low ebb in New Mexico which has few negroes, but also in 
West Virginia which is comparatively free from both negroes 
and Mexicans. Moreover, Texas, where the colored people form 
only a fifth of the population, stands lower than South Caro- 
lina and Mississippi, where half the people are colored. Another 
significant fact is that the education of negroes varies from state 
to state almost as does that of whites. Although a smaller pro- 
portion of negroes than of whites go to school, the two races 
are well or poorly educated in the same places. In Figure 38 the 
figures for states with a moderate number of negroes, such as 
Virginia with 80 per cent, give a fairly correct impression, but 
the impression is not so accurate in those states where there are 
many negroes. The reason is that our index figures for states 
with many negroes are too high by reason of our assumption that 
all the high school graduates are white. Disregarding these minor 
discrepancies it seems quite clear that the degree of education is 
not proportional to the number of colored people. The southern 
states differ among themselves because of special circumstances 
such as good or bad laws, but all stand low because of more gen- 
eral factors. These factors give to Figure 38 its general char- 
acter, and seem to make it as good an epitome of the general dis- 
tribution of culture in the United States as we are yet able to 
obtain on the basis of the statistics of a single activity. Neverthe- 


less, it can scarcely be doubted that the general level of the 
South is much lower than it would be if there never had been any 
colored people there, but that would not change the general 
aspect of Figure 38. 

Let us now compare our educational map with Figure 37, 
which represents the distribution of civilization in the United 
States according to the opinion of 23 people. All of these except 
Ambassador Bryce were Americans. They grouped the states 
and provinces of the United States and Canada into six classes, 
number 6 being the highest. Massachusetts is the only state 
invariably placed in the highest class. New Mexico and Arizona, 
which stand lowest, have an average rank of 1.6. In order to 
judge how much reliance to place on the classifications, I took 
the first ten that were received and averaged them, and when ten 
more had come to hand averaged them also. Somewhat to my 
surprise, and much to my pleasure, the two sets of averages were 
practically identical. How much they differed may be seen in 
the Appendix. The average difference is only 0.2, and the maxi- 
mum 0.6. The agreement of the two sets probably indicates that 
any other group of equally well-informed persons would have 
made essentially the same classification. To be sure, in spite of 
several attempts, I was unable to obtain any contributor in the 
states west of Minnesota or south of the Ohio River. Local 
prejudices, however, have probably not exerted much effect on 
the final results, for California stands in the highest class, with 
practically the same grade as Minnesota and Iowa. 

A comparison of the maps of civilization (Figure 37) and 
education (Figure 38) is interesting. In general aspect the two 
are similar. Both have two high areas, one in the northeast and 
center, and the other on the Pacific coast. In both there is a 
decline from north to south. Another common feature is a tongue 
of high conditions jutting out toward Kansas. This eastern high 
area and its western counterpart are almost identical with those 
of the map of civilization. In both maps Massachusetts takes 


first place. In the map of progress Connecticut, New York, and 
Ohio come next, all three being equal: in the educational map 
the rank is Connecticut, New Jersey, Washington, California, 
Ohio, Utah, Oregon, and then New York. Judging by this our 
eastern contributors to the map of progress did not quite do 
justice to the Pacific coast. Nevertheless, the differences among 
the states just mentioned are too slight to be important. 

The only real discrepancies between Figures 37 and 38 are 
the high position of Utah in the educational map, which has 
already been explained, and the absence of the low tongue jutting 
into Nevada. This is perhaps due in part to an undue lowering 
of the general educational level of the Southeast by reason of 
the negroes. Also the contributors to the map of progress prob- 
ably paid too much attention to aridity, sparseness of popula- 
tion, and the ephemeral character of mining towns, and nob 
enough to the fact that the inherent quality of the people of 
newly settled regions is almost invariably high. The process of 
selection incident to migration, as I have shown in The Char- 
acter of Races, goes far to insure such quality, provided the 
migration is unassisted and is beset with sufficient difficulty. 

In concluding this chapter, let us look at another criterion 
which is often supposed to be closely associated with civiliza- 
tion. This is the percentage of the population engaged in manu- 
facturing. It is often asserted that manufacturing is most pre- 
dominant in places where supplies of coal and iron are present, 
but this is a mistake. A mathematical analysis of the states of 
the United States by means of correlation coefficients shows that 
there is no relation whatever between the amount of coal mined 
per inhabitant and the percentage of the population engaged in 
manufacturing. In the world as a whole the same is true; we 
have been misled by the accidental circumstance that England, 
western Europe, and the United States happen to be places 
where coal is very abundant. But, relatively speaking, those 
regions stood just as high in civilization before the age of ma- 


chinery as since. They were leaders then as now. The important 
factor in determining the presence of manufacturing is the char- 
acter and energy of the people. If anyone doubts this, let him 
study the progress of manufacturing in Switzerland, Sweden, 
New England, Japan, or on our own Pacific coast, in spite of 
small supplies of coal. Hence Figure 39 (page 284), showing the 
percentage of the population engaged in manufacturing, is in 
many ways a map of the distribution of progress. It also reflects 
the location of certain natural resources such as cotton in the 
South and Cuban tobacco which is manufactured on a large scale 
in Florida at Tampa and Jacksonville. Nevertheless, the main 
aspects of Figure 39 are surprisingly like those of Figures 37 
and 38. The similarity of our maps of education and manu- 
facturing to one another and to the map of progress based on 
the opinions of our twenty-three contributors, is too close to be 
accidental. It seems to show that all three present a fairly accu- 
rate portrayal of the actual distribution of human progress. 
Since our two maps of climatic energy likewise not only resemble 
one another but are closely similar to the map of mortality, we 
may feel fairly sure that in all parts of the world the same rela- 
tionship holds true. 


WE have now reached a crucial point in our investigation. 
We must compare the distribution of civilization and 
of climatic energy. The reader has doubtless noticed that our 
maps of climatic energy in the United States, whether based on 
factory work or health, display an unmistakable similarity to 
the maps of human progress based on education, manufacturing, 
and general opinion. In spite of minor discrepancies, all the maps 
show the following features: (1) a high area elongated east and 
west from New England and New Jersey to a little beyond the 
Mississippi, (2) another and much narrower high area elongated 
north and south along the immediate coast of the Pacific Ocean, 
(8) a decline from north to south in the east, and (4) a low bay 
running across the country in the Rocky Mountain region, with 
a pronounced accentuation in the dry Southwest. 

While these details are fresh in mind let us turn to three maps 
of Europe showing the relation of climatic energy (Figure 40), 
health (Figure 41), and progress (Figure 42). The map of 
climatic energy is based on our factory data but with some modi- 
fication, because we have found that the optimum temperature 
for health is 64 or 65 rather than 60 as was inferred from 
factory work. The second map shows the distribution of health. 
It is based on the official mortality statistics of the European 
countries for the years 1909-1913. Infants under one year of 
age and old people over seventy-five have been omitted because 
the figures for those groups, especially the infants, are unre- 
liable. The data for other ages have been reduced to what is 



called a standard population, so that differences in age and in 
the proportion of children from country to country have been 
eliminated. The map shows the actual distribution of health in 
Europe under normal conditions. The third map illustrates the 
distribution of civilization. It is the same as Figure 23 in the 
chapter on civilization, but is reproduced here in another form 
in order that it may easily be compared with the other two. 

From Huntington and Williams' Business Geography, by permission of 
John Wiley <& Sons, Inc. 

Figure 40. Distribution of Climatic Energy in Europe 

These three maps are so much alike that if the titles were 
removed, most people would not be able to tell which is which. 
In each map an area of heavy shading surrounds the North 
Sea, and shades off gradually in every direction. In each there 
are three projections of heavy shading, one toward Italy, a 

From Huntin'jton and Williams' Business Geography, by permission of 

John Wiley c Sons, Inc . 
Figure 41. Distribution of Health in Europe 

80 10 10 20 80 40 6O 60 TO 

From Huntington and Williams 1 Business Geography, by pvi mission of 

John Wiley <& Sons, Inc, 
Figure 42. Distribution of Civilization in Europe 


second toward the Black Sea, and a third along the Baltic. The 
maps are so much alike that there can scarcely be any question 
as to the reality of their relationship. And that relationship can 
be of only one kind. Civilization and progress undoubtedly influ- 
ence health, and health in turn has an effect on progress. But 
neither civilization nor health can have any appreciable effect 
upon the distribution of climate. The only way in which the three 
maps can be so alike, unless by sheer accident, which is practi- 
cally impossible, is for climate to exert a direct and dominating 
influence upon the distribution of health and an indirect and 
perhaps less dominating influence upon civilization through 
other agencies, such as agriculture. 

Now turn to the world as a whole. Unfortunately the mor- 
tality records of many backward countries are highly inaccu- 
rate, while for vast areas they are wholly lacking. Hence it is 
impossible to construct a map of health. We can, however, con- 
struct maps showing the distribution of climatic energy and of 
civilization. A map of climatic energy based on factory work 
has already been given in Figure 22. This is repeated in Figure 
43. The map of civilization on the same page, Figure 44, sums 
up the data already shown in Figures 23 to 28. All regions to 
which our fifty contributors assign a rank of 8.5 or higher are 
rated as "very high," and are shaded in solid black. Those from 
7 to 8.5 are rated as "high," and arc shaded in heavy lines ; those 
from 5 to 7 are "medium," and are indicated by light lines ; 3 to 
5, "low," shaded with abundant dots ; and under 3, "very low," 
and dotted only lightly. 

The first thing that attracts attention is the general resem- 
blance between the maps of energy and of civilization. Both, for 
example, show a high area in northwestern Europe. A tongue 
extends into Italy, another toward Roumania, and a third to 
the Baltic. Another projection runs out into western Siberia. 
Here the high area of the map of civilization extends about as 
far as the medium area of the map of energy. This is not surpris- 

(66 W MO K9 100 HO 60 49 O AO 40 60 80 309 MO 240 

Figure 48. The Distribution of Human Health and Energy on the 

Basis of Climate 

Figure 44. The Distribution of Civilization 


ing, for even if the people of Siberia have the energy indicated in 
Figure 43, they are hampered by the remoteness and newness 
of their country, not to mention other conditions. In central and 
northern Siberia, the difference between the two maps is slight. 
The significant thing is that in both there is the same falling off 
toward the center of Asia. Still farther east in China and Japan 
conditions are once more alike, China being medium and Japan 

In Indo-China and especially in India, the maps differ. Appar- 
ently, this arises largely from European domination, and is due 
to the constant addition of strength from that continent. This 
does not apply to Siam, however, which has worked out its own 
salvation. It ranks as very low on the energy map, and only as 
low on the other. This may have no significance, for our maps 
are still in their early stages. Further knowledge may change 
such slight disagreements into agreements. On the other hand, 
it may increase the disagreement. In that case we may discover 
that by long residence within the tropics, the races of Indo-China 
and India have become differentiated from Europeans and are 
less susceptible to the influence of steady heat. Again, race 
differs from race in its inheritance, and the Siamese may inherit 
stronger traits than are possessed by their neighbors. Finally, 
the level of Siamese civilization may have been raised by contact 
with other races, by the adoption of particular institutions of 
government, forms of religion, or social organization, or by the 
inspiration and energy of a few men of unusual gifts. I mention 
these possibilities not because they are of special importance in 
Siam, but because they illustrate the many and varied influences 
which cooperate to determine the position of a country in the 
scale of civilization. 

In comparing the maps of energy and civilization, one of the 
clearest features is the effect of a strong race upon regions 
which it rules or colonizes. Again and again the presence of such 
a race causes a region to be higher in civilization than would be 


expected on the basis of climatic energy. Java, the Philippines, 
and India are examples. It is especially noticeable in regions 
controlled by Great Britain. In Australia, for instance, the 
general decrease in both civilization and energy from southeast 
to northwest is the same in both maps, but the presence of the 
English raises the places of "very low" energy to "low" in 
civilization, and so on, each grade being raised one degree, so to 
speak, until the map of civilization shows a large high area in 
the southeast. In South Africa and Egypt, British influence 
is displayed in the same way. In the Canadian Northwest, on 
the other hand, it is not apparent. The northern parts of Alberta 
and Saskatchewan appear higher in energy than in civilization. 
We have already seen that according to American and, to a less 
extent, British opinion, this is not the case, for recent settlement 
has raised these regions to a comparatively high degree of 

In the United States the energy map shows a strip of medium 
conditions along the southern frontier, but this is rated as high 
on the other map. Such a condition illustrates how a high type 
of government causes efficient people to settle in unfavorable 
regions, and how it also adds to the effectiveness of less efficient 
people such as Mexicans and negroes, thus in part overcoming 
the handicap of climate. In the central states, on the other hand, 
civilization is not rated so high as one would expect on the cli- 
matic basis. Probably this is because the country is so new that 
our Chinese, Russian, Spanish, and other foreign contributors, 
though they have traveled and studied extensively, do not realize 
how great is the progress of recent times. California, like the 
southern states, is higher on the map of civilization than on the 
other. As already explained, this may in part be due to the im- 
possibility of making a wholly accurate map of climatic energy. 
It may also arise from the location of California on the sea- 
board, and from its early development as contrasted with the 
newer states of the interior. A comparison of the United States 


as it appears on the world-maps and as it appears on the maps 
of that country alone is important. Where the country stands 
by itself, and its parts are classified by people who live in it 
and are thoroughly familiar with it, the resemblance between 
climatic energy and civilization is greater than where the classi- 
fication is on a rougher scale and is made by people less familiar 
with it. Another reason for the difference is that a classification 
of places where a uniform standard of culture prevails and where 
the same race is everywhere dominant is much easier than where 
many types of culture and highly diverse races are considered. 
The maps of the United States represent the kind which must 
be made for each country. The difference between the features of 
the United States on the world-map and on the other represents 
the extent to which our general map of civilization is in error. 
In spite of this, however, the general features of the country are 
unmistakably the same on both maps. So far as the conclusions 
of this volume are concerned, it makes no difference which we use. 
In this lies the importance of our various tests of the United 
States. They show that although much remains to be done before 
we can construct a map which is approximately perfect, the 
most important features are reasonably distinct and unmis- 

Turning to Latin America, we find about what would be ex- 
pected in Mexico and Central America. The highlands are me- 
dium and the lowlands low. South America, on the contrary, 
presents some unexpected features. The Andean highlands, 
including Venezuela, Colombia, Ecuador, Peru, and Bolivia, are 
all ranked as low in civilization, whereas the climatic map would 
indicate medium energy. In the belt of highlands on the east 
side of Africa the same phenomenon is observable. Perhaps an 
equatorial climate is more debilitating than would be expected 
from the work of factory operatives in summer. In South 
America the presence of an ancient race whose vigor was already 
waning at the time of the discovery of the New World has doubt- 


less hindered Spanish immigrants in accomplishing what might 
otherwise have been looked for. This, however, does not alter the 
case, for the original inhabitants in the Andean countries, just 
as in the African highlands, stand lower than would be expected. 
Argentina, on the contrary, goes to the opposite extreme, and 
is higher on the map of civilization than on that of energy. The 
importance of this must not be overrated, for the climatic data 
are somewhat doubtful because of the paucity of statistics as to 
changes of temperature from day to day. As the maps now 
stand, however, they are encouraging, for they suggest that 
even with a moderately favorable climate, the Latin race in 
America is competent to rise to a high level. 

Let us turn now from these details, and look once more at the 
general aspect of the two maps. In spite of minor disagreements, 
the main features are essentially alike. There are, in each case, 
the same two great high areas in western Europe and the United 
States. The decline from western Russia eastward to the center 
of Asia, and the rise to high conditions on the eastern edge of 
Asia in Japan are equally apparent. Likewise, the maps are 
strikingly alike in the shape of the very low areas in Africa and 
South America. South of latitude 30 S. each of the southern 
continents begins to rise in energy and in civilization, and the 
rise is more pronounced on the eastern side than on the western. 
Even where the maps disagree, the explanation of the disagree- 
ment is often obvious from a consideration of the recent move- 
ments of European peoples. Some of the remaining discrep- 
ancies are explicable on well-known grounds, such as the 
impossibility of agriculture, which hinders civilization in the far 
northern parts of America and Asia. In addition to all this many 
differences in the degree of progress among people in similar 
climates are due to racial inheritance. A conspicuous example of 
this sort, as I have shown in The Character of Races, is the 
contrast between the progressive Icelanders and the backward 
people who live in a similar climate in the southern tip of South 


America. A still more conspicuous example is the difference 
between the primitive hill tribes of India and the highly compe- 
tent Parsis whose ancestors came to India more than a thousand 
years ago because of their loyalty to their old Zoroastrian reli- 

When allowance is made for obvious facts like these, the re- 
semblance between the two maps becomes more striking. Call to 
mind the method of their construction. Neither represents the 
personal opinion or bias of any one man. Any other person with 
the same data before him would have obtained similar results. 
The maps simply give expression to two distinct sets of facts. 
The first is that the opinion of men of many races agrees as to 
the general distribution of civilization. The second is that if 
the various conditions of climate produced the same effect upon 
all the people of the world as upon students and factory opera- 
tives in the eastern United States, the amount of work accom- 
plished in different countries would be closely proportional to 
the status of civilization. 

Aside from the map of climatic energy, it is hard to think 
of any other which would so closely reproduce the features of 
the map of civilization. Suppose that race were made the cri- 
terion, and that a map were shaded in proportion to the number 
of Teutons. We should find that in Europe such a map would 
closely resemble the map of civilization except that places like 
Finland, southern France, central Italy, Hungary, Bohemia, 
Servia, and others are relatively high in civilization even though 
none are more than half Teutonic, and some only very slightly, 
or almost unappreciably so. In Asia, on the other hand, there 
is much more Teutonic blood in Syria and Asia Minor than in 
Japan, yet Japan ranks far higher. The Japanese might claim 
racial superiority almost as fairly as the Teutons, and both the 
Latins and Slavs may justly point to the fact that they pre- 
dominate in some of the most advanced portions of the globe. 
When we look at the low places, we find that Teutonic areas, 


such as the Transvaal, Alaska, southern Greenland, and parts 
of Australia make a poor showing; the Latins in parts of Latin 
America are even worse ; the Slavs at their worst fall no lower 
than the Teutons ; while the Japanese nowhere fall so low. 

A map of religion does not resemble a map of civilization, no 
matter which religion is employed. Protestant Christianity, 
indeed, prevails chiefly in regions which are either high or very 
high; Iceland is by no means an exception, for its civilization 
is much higher than would appear from our table, where it is 
grouped with Greenland. Roman Catholic Christianity, on the 
other hand, prevails in locations which range from very high 
to very low ; and Greek Christianity from high to low. Buddhism, 
likewise, ranges from high in Japan to low in Tibet, while Mo- 
hammedanism never rises above medium, and in some places falls 
very low. That religion raises or lowers the tone of a country 
I do not for a moment question, but if a people are physically 
weak and are lacking in self-control because of something in 
their surroundings, the history of the world as exemplified by 
groups of people who have long been nominally Christians in 
Abyssinia, India, Latin America, and elsewhere seems to show 
that they debase even the finest religion. The higher the form of 
religion and the more self-sacrifice and devotion it requires, the 
more difficult it becomes to keep any but the most energetic and 
determined races even approximately true to it. The only cases 
where people of low efficiency seem to remain true to a high 
religion are where they are continually stimulated by the pres- 
ence of a stronger race. 

As a third criterion, suppose that we take form of govern- 
ment, and inquire whether a map of governments would resem- 
ble one of civilization. Of course, the excellence of the govern- 
ment is closely related to the degree of civilization, but not so 
with the form. Republics range from very high in Switzerland 
and France to very low in Venezuela. Limited, but autocratic 
monarchies existed in high countries like Germany, at least, 


before the great war, and also in low countries like Turkey and 
Persia. Thus we might go on to consider one after another of 
the great factors which cooperate in giving form to modern 
civilization. The nature of a nation's religious faith, its form of 
government, its social organization, its ease of intercourse with 
other nations, and various other conditions play a fundamental 
part in the distribution of civilization. Yet each is conditioned 
by the degree of energy possessed by a people, for if a race lacks 
energy, no amount of excellence along other lines will place it in 
the first rank. Energy, in turn, is greatly influenced by climate, 
and thus climate becomes an essential element in determining the 
status of civilization. We may well reverse our statement, how- 
ever, and say that no amount of energy will make a nation great 
if none of its people are gifted with genius, or if it never evolves 
an orderly form of government or a moral code which allows a 
man to enjoy life, property, and home without constant fear of 
outsiders Thus, the material and immaterial elements of civiliza- 
tion play into each other in such a way that either seems the 
more important according to the angle from which we view it. 
The interplay of diverse factors is so important that it is 
worth while to examine it in a concrete case.* Dr. Scott Nearing 
in the Popular Science Monthly for 1914 published an article 
entitled, "The Geographical Distribution of American Genius.' 
While it is impossible to measure genius, it is possible to ascer- 
tain how many people of unusual ability are born in a given 
region. That useful publication, Who's Who in America, though 
not infallible, forms a good summary of about twenty thousand 
people who have either achieved "special prominence in credit- 
able lines of effort, making them the subjects of extensive inter- 
est, inquiry, or discussion in this country," or who occupy 
positions which could scarcely be attained except by persons of 

* The following discussion is reproduced unchanged from the first edition 
of this book. In The Character of Races I have considered the changes in the 
past ten years, but they do not alter the conclusions set forth below. 


unusual ability. Taking Who's Who for 1912-1913 as a basis, 
Nearing has tabulated the birthplaces of the first 10,000 names 
according to states. He took only 10,000 because that number 
seemed enough to give reliable results. His tabulation strikingly 
reenforces the common opinion that New England, especially 
Massachusetts, has produced far more than its proportionate 
share of persons of unusual ability. The utility of his investiga- 
tion seems so great and the method so reliable that I have asked 
Dr. Nearing for permission to make use of fuller data than were 
contained in his article, and he has kindly supplied me with the 
figures for each state. In order to determine the relative status 
of the various parts of the country it is not fair to compare the 
number of eminent persons who were born in a given area with 
the present population. At the time when the men who are now 
prominent were born many of the western states contained only 
a handful of settlers. It is equally unfair to compare the number 
of such persons who live in a given region with the present popu- 
lation, for many persons who have achieved prominence owe it 
to the place where they grew up and not to that where they now 
live. The only fair way seems to be to ascertain the relation 
between the number of eminent persons born in a given region and 
the population of the region at the time of their birth. Accord- 
ingly, the first thing to do is to find when the people in Who's 
Who were born. Nearing gives the following table : 



Before 1850 2,818 

1850-1859 2,715 

1860-1869 2,717 

1870-1879 1,304 

1880-1889 95 

1890-1899 2 

Unknown 349 

Total 10,000 



The number who were born before 1840 is not given, but it 
must be considerable, for the people who attain eminence are 
among the most long-lived portions of the community. On the 
other hand, the number who were born after 1880 is too small to 
be considered. People rarely become eminent before they are at 
least thirty-five years of age. The forty years from 1835 to 
1875 cover the births of practically all who had attained suffi- 
cient distinction to be included in Who's Who for 1912. Accord- 
ingly, we must find the average population of each state accord- 
ing to the censuses from 1840 to 1870, but inasmuch as the 
number who were born previous to 1840 is less than in later 
decades, we shall come nearer to the truth if we give that census 
only half as much weight as the others. In all cases we employ 
the figures for the entire white population, whether native or 
immigrant, but omit the negroes, Chinese, and Indians. The way 
in which the matter works out is illustrated in the following 
table, where the population is given in thousands : 

White population in thousands 








South Carolina 












New Mexico .... 

The figures in the last column show the relative rank of these 
states in the production of persons of unusual ability from 1835 
to 1875. Similar figures for each state are given in Figure 45. 
Since Nearing used only the first 10,000 names of American- 
born persons in Who's Who, or only about 60 per cent of the 
total, the index figures really mean the number of eminent 
persons for every 60,000 people instead of 100,000. In a few 


cases where the average population previous to 1875 was less 
than 10,000, two or more adjacent states have been combined 
so as to give a total large enough to be significant. The numbers 
thus obtained have been enclosed in parentheses. On the map the 
United States has been divided into four grades, much as in 
Figures 34 to 39. Thus all these maps are comparable. The only 
essential difference is that Figure 45 belongs to a period averag- 
ing more than half a century earlier than the others. It presents 
the most accurate picture now available of the distribution of 
ability at that time. New states are at no disadvantage compared 
with the old, for if a region had no population previous to 1860, 
for example, and only a few thousand in 1870, full allowance is 
made for this. Many of our 10,000 eminent people have moved 
away from their early homes, but the great majority did not 
go until they had at least reached an age approaching twenty 
and the main elements of their character were already formed. 
Thus the peculiarities of the map depend not only on whether the 
population was of such a caliber that children of high ability 
were produced, but also on the conditions which molded the early 
life of such children. 

Aside from accidents three chief conditions determine the num- 
ber of eminent persons in a community. The first is inherited 
ability. Unless a man is born with more than the average mental 
capacity, the chances of his inclusion in Who's Who are slight. 
The second condition is opportunity in the broadest sense of the 
word. A bright child born on a remote farm in Maine, on a ranch 
in Arizona, or in a clearing among the Tennessee mountains may 
be so hampered by lack of education and of the stimulus derived 
from contact with people outside his own little circle that he 
never accomplishes anything that attracts attention. The third 
condition is energy. Many a man of high ability, who is also 
blessed with the best education and with all sorts of opportu- 
nities to develop his talents, fails to make any impression on the 
world because he is indolent. Frequently, a man of less ability 


but endowed with energy achieves much more. Energy depends 
partly on inheritance, but also on climate. So far as it depends 
on inheritance it should be included under the first of our three 
conditions. Thus the three may be briefly defined as (1) inherited 
qualities of all kinds, (2) opportunities, which include educa- 
tion, the degree of culture in a community, and the freedom with 
which a person can find scope for his particular talents, and (3) 
energy so far as this depends upon physical circumstances not 
connected with either heredity or opportunity. 

Let us now inspect Figure 45 to see how far our three con- 
ditions make themselves evident. Each gives rise to certain 
features which stand out unmistakably. To begin with inherit- 
ance, Massachusetts gave birth to 98 eminent persons for every 
60,000 of its white population during the specified period. That 
is, 1 white child out of every 600 born at that time has dis- 
tinguished himself. The figures for the surrounding New Eng- 
land States and New York range from 50 to 78. Such a striking 
difference is certainly not due to climate. It is equally certain 
that it is not due to opportunity. The average child in New 
York has as good a chance to go to school and enter any sort of 
occupation as has the child in Massachusetts. Yet the rank of 
New York is only half as high as that of Massachusetts. In 
Maine, Vermont, and New Hampshire the opportunities are dis- 
tinctly less than in New York. There is much less wealth, the 
people are more isolated, the number of cities is proportionately 
smaller, the common school system is no better developed, and 
the facilities for sending children to college are not so great. 
Yet even Maine outranks New York, for she produced 54 emi- 
nent persons per 60,000 while New York produced only 50. Yet 
New York itself stands very high. Aside from the New England 
States only Nebraska exceeds it, while Oregon and Delaware 
rival it. South Carolina is another state which stands far higher 
than its neighbors, for although 39 is low compared with the 
78 of Connecticut, for example, it is high compared with the 24 



of North Carolina and the 25 of Georgia. Probably, heredity 
plays an important part here, as in other cases ; although, as we 
shall shortly see, the matter is complicated by other conditions. 
Oregon and especially Nebraska, however, are unmistakable. 
Proportionately, they stand as high above their neighbors as 

Figure 45. Birthplaces of Persons of Unusual Ability in the United States. The Nu- 
merals Indicate the Number of Eminent Persons Born in Each State per 60,000 of 
the Average White Population from 1835 to 1875 

Massachusetts, Connecticut, Rhode Island, and Vermont above 
theirs. The case of these two states is most suggestive. So far 
as energy is concerned, there is nothing in the climate of either 
Oregon or Nebraska to give them a special advantage. Previous 
to 1890, by which time the education of four fifths of the people 
in Who's Who was completed, these two states did not offer 
their children especially great opportunities. In fact, the oppor- 


tunities were much less than in Oregon's next neighbor, Cali- 
fornia, or in Iowa, Illinois, Indiana, Ohio, and Pennsylvania, the 
states directly east of Nebraska. Yet Oregon ranks 30 per cent 
higher than California, and Nebraska exceeds Illinois by 60 per 
cent, and Indiana by over 90 per cent. In striking contrast to 
Nebraska we find New Mexico with a rank of only 1.5, which 
appears as 2 on the map because we have avoided the use of 
fractions. Here again neither climate nor opportunities explain 
why this state falls so far behind its neighbors. The only reason- 
able explanation is that until 1870 or later its "white" popula- 
tion consisted almost wholly of Mexicans. 

In reading the preceding pages it may have occurred to the 
reader that the preeminence of New England is only apparent, 
not real. It may be due largely to the local prejudices or limited 
viewpoint of the compilers of Who's Who. This is not the case, 
however. The book is edited and published in Chicago. Yet 
Illinois and the neighboring states all receive a relatively low 

The facts just stated are of profound significance. Massachu- 
setts, because she was settled by the strong-willed Pilgrim 
Fathers and by other Puritans who fled to the wilderness to 
maintain their high ideals, has produced vastly more than her 
proportion of the men who have made America what it is. Con- 
necticut and Rhode Island for similar reasons have followed 
closely on her heels, while the northern New England States 
have much more than held their own compared with the rest of 
the country. It has been a fad to decry puritanism, but people 
of puritan descent have taken the foremost place. They have 
done so because they inherit the strength of mind which made 
it possible for the Puritan Fathers to develop their stern con- 
scientious system and carry out their noble purposes in the face 
of temptation and opposition. When that old stock has been 
transported to places such as Nebraska and Oregon, where for 
a while it was dominant before the great tide of later immigra- 


tion, it raised the average ability to a level reached nowhere else 
except in New England. In New Mexico, on the contrary, we 
harbor a group of people, fortunately small, who are even more 
conspicuous by their lack of ability than the New Englanders 
are in the opposite way. We may excuse the Mexicans by saying 
that they do not learn our language and do not merge them- 
selves in our civilization. The competent Mexicans, however, 
usually those who possess the greatest proportion of Spanish 
blood, do learn English and make themselves felt among us. The 
others, perhaps because they inherit an inert disposition from 
their Indian ancestors, are content to remain backward. 

This brings up the great question of immigration and racial 
character. In the earliest days of colonization we received only 
the stronger elements of the various European populations. The 
North had its Pilgrims, Puritans, Quakers, and others, while in 
the southern states a part of the settlers were people who as 
Huguenots or other religious refugees were notable for tenacity 
of purpose and high ideals. The rest of the settlers were in large 
measure people of unusual courage and initiative, for others were 
not brave enough to come. For this reason, apparently, the 
states of the Atlantic coast from Georgia northward stand 
higher than those west of them. After America had been settled 
so long that migration thither was easy, we began to get immi- 
grants of medium grade, not the best nor the worst, but from 
advanced countries and from the substantial middle classes. 
These are what predominate from Pennsylvania to Iowa. They 
are good material, but not so good as the old. Otherwise why 
should so fine a state as Wisconsin have produced only half as 
many eminent men per 100,000 as has Connecticut, and no more 
than South Carolina, which labors under far greater disad- 
vantages? In these last decades we are taking into our midst 
many people scarcely better than the Mexicans. We may say 
what we choose about absorbing them and making them good 
Americans. It is our duty to do so as far as we can, but why 


blind ourselves to the facts of biology? Plough horses cannot 
race like thoroughbreds. Do men gather grapes of thorns or 
figs of thistles ? 

Today Massachusetts and New England seem to be losing 
their supremacy in the production of men of special ability. 
A study of Who's Who for 1922 shows that the conditions of 
ten years earlier still prevail, although less marked. But where 
the old New England families have sent their sons out over the 
wide expanse of our land, the loss to the mother states is more 
than compensated by the gain to the rest of the country. Unfor- 
tunately, the change means more than that. It means, first, that 
we are steadily diluting our strength. We are acting as would 
a dairyman who thought that by adding a dozen low-grade ani- 
mals to his herd of a hundred prize-winners and letting them 
breed together he was going to increase the value of his stock. 
In addition to this we are losing in another and more dangerous 
way. It is as if the dairyman should not only add poor animals, 
but should also prevent his best animals from bearing young. No 
amount of care would make the low-grade animals give as much 
milk or be of as much value as the prize-winners. Man is subject 
to the same biological laws as animals. High mental ability and 
strength of purpose are his most valuable qualities. Yet we act 
as if we thought that though these are not reproduced, our coun- 
try can continue to advance. Our unwillingness to live simply 
either prevents a large proportion of our most competent men 
and women from marrying, or causes many of those who marry 
to have few children. All men are not created equal biologically, 
and it is the best who are dying out. We must recognize that fact, 
and act upon it before we have worked irreparable injury. All 
this has been said many times by eugenists, but it must be 
repeated again and again until it is not only believed but acted 
upon. Biology teaches it; common sense insists upon it; and 
now our purely geographical studies enforce the same con- 


The second condition which controls the distribution of people 
who attain eminence is opportunity. This appears unmistakably 
in only one portion of Figure 4<5, but there it stands out sharply. 
Notice how West Virginia with 19 eminent persons per 100,000, 
Tennessee with 18, and Arkansas with 11 fall below the sur- 
rounding states. This is apparently because these are the por- 
tions of the South where mountains and other physiographic 
disadvantages cause the people to degenerate into "poor whites" 
and "crackers" in spite of a good inheritance. What these back- 
ward communities need is a "chance." They need the opportu- 
nities that are brought by schools, railroads, factories, and the 
other appurtenances of civilization. They need also the oppor- 
tunity brought by freedom from such bodily afflictions as the 
hookworm disease. Kentucky, which now has a rank of 23, would 
probably stand much higher were not a large part of the state 
peopled by mountain whites. The same is true of North Caro- 
lina. Perhaps this state would not equal South Carolina, which 
had a large number of old families of unusual ability, but the 
two would be much nearer than now. A large fraction of North 
Carolina consists either of mountains or of swampy, unhealthy 
tracts along the coast, while South Carolina is almost free from 
such disadvantages. In another portion of the country it may 
be that Maine lags behind New Hampshire and Vermont in part 
because of her relative remoteness and lack of opportunity. 
Doubtless other places show the same conditions, but the matter 
is not certain. For example, Nevada's low position with a rank 
of only 15 is probably due in part to this cause, but it is doubtful 
whether she has been much worse off than Utah, which has the 
respectable rank of 36. Idaho, Wyoming, Montana, and the 
Dakotas certainly had no more opportunities than Nevada 
previous to 1890, for they were supplied with fewer railroads, 
and were much less easily in touch with the rest of the world. 
Yet their rank is 33, or more than twice that of Nevada. Taking 


the map as a whole it seems that although opportunity is highly 
important, it is less important than heredity. 

The preceding paragraph stands as it was written ten years 
ago. Today I am inclined to think that I have not given sufficient 
weight to inheritance in estimating the position of the mountain 
whites. Note first, however, that in Figure 36, where climatic 
energy is estimated on the basis of the effect of climate on health, 
the mountain white region, by reason of its altitude, forms a 
peninsula of more favorable conditions jutting southward. Some 
non-climatic factor seems completely to overshadow this climatic 
condition. That this other factor is in part the isolation of the 
mountain valleys I do not doubt. But this is probably supple- 
mented to a large degree by inheritance. When people are able 
to move freely from one region to another, there is a strong 
tendency for those who are most competent to gain possession of 
the best places. The rich cotton soil of the Black Belt of Georgia 
and Alabama, as R. M. Harper has well shown, has attracted 
and held a large number of unusually competent families the 
kind that produce leaders. In such a region the lands of the less 
competent people are gradually bought by the competent. The 
less competent often move into the mountains, where land is 
cheap. There is likewise a backward movement whereby the most 
competent mountaineers drift to the lowlands. Thus in course of 
time there arises a genuine inherent difference of ability, and 
that may be one cause of the backwardness of the mountain 

Turning now to our last factor, that is, energy as determined 
by climate, we see that, in general, the outlines of Figure 45 are 
like those of the climatic map in Figure 36. To be sure there 
are important differences. For instance, the very high area 
which covers all the northeast and center of the country in the 
energy map is split into a New England and a Nebraska por- 
tion in the map of ability. Yet the Nebraska area of many emi- 
nent people displays an interesting resemblance to the tongue 


which projects out in the same direction on the energy map. 
The Pacific coast is likewise high on both maps, although there 
are differences of detail. Nevada, too, is at the head of a tongue 
of low conditions in both cases. On the Atlantic coast both maps 
rise from Maine to Massachusetts, and decline from New York 
to Florida. In the map of ability, however, high conditions go 
somewhat farther south than in the other map, and South Caro- 
lina, presumably because of heredity, rises unexpectedly. The 
other southern states from Georgia to Louisiana are also a little 
higher on the ability map than on its companion, probably 
because of the wealth and opportunities which prevailed in them 
previous to the Civil War, or else because of the abundance of 
old families with high ideals and strong minds. Yet even these 
states are lower than the tier of northern states from Pennsyl- 
vania to Iowa, where the average inheritance is probably no 
higher, if as high, but where the climate gives energy. 

Taken as a whole the map of ability is an admirable example 
of the way in which a variety of factors cooperate in determining 
the status of civilization. Climate, as it were, paints a broad 
background, shading gradually from very high in certain areas 
to lower in others. Then the other factors come into play. They 
paint fresh colors which may or may not resemble those of cli- 
mate. In some cases, such as Massachusetts, the same color is 
laid on by climate, heredity, and opportunity, not to mention 
proximity to the sea and to Europe, facilities for manufactur- 
ing, and various other factors which perhaps may be considered 
as opportunities. Where that happens, high civilization is sure 
to prevail. In other cases, such as South Carolina, the climate 
paints only a moderately high color, inheritance paints a higher 
one, education a low, the presence of the negroes a still lower, 
and so on indefinitely. 

Such, then, is the meaning of our maps. They do not indicate 
that climate is the only factor in determining the condition of 
civilization, or even the main one. Far from it. Yet they indicate 


that it is as essential as any other. Today civilization seems to 
make great progress only where a stimulating climate exists. A 
high civilization may be carried from such places to others, but 
it makes a vigorous growth and is fruitful in new ideas only 
where the climate gives men energy. Elsewhere it lags, or is kept 
at a high pitch only by constant reinforcements from more 
favored regions. In the past men have perceived that climate is 
apparently one of the most important conditions which favor 
or retard the growth of civilization. They have been greatly 
impressed not only by its effects upon their own bodies and 
minds, but by the fact that in warm countries the amount of 
progress is closely in harmony with what would be expected on 
the basis of one's own feelings. At the same time they have 
realized that among countries located in the same latitude there 
are differences of culture almost as great as between temperate 
and tropical countries. This has seemed to indicate that climate 
is not so important as the tropical regions would suggest. Now, 
however, we see that when people's actual achievements under 
various climatic conditions are measured, we must revise our 
opinion. Variations of temperature from day to day are much 
more important than has been realized. Therefore, in the same 
latitude the stimulating effect of the climate may differ greatly. 
The civilization of the world varies almost precisely as we should 
expect if human energy were one of the essential conditions, and 
if energy were in large measure dependent upon climate. 


WE now have before us the main hypothesis of this book, 
as stated at the end of the last chapter. But even if 
many facts suggest that civilization at present varies from place 
to place almost precisely as we should expect if it were dependent 
upon climatic energy and health, is there not abundant evidence 
to the contrary? Three objections at once present themselves: 
(1) The great nations of antiquity developed their culture in 
regions where the climate is now relatively unstimulating. (2) 
The American Indians, even when they lived in some of the 
world's best climates, failed to evolve a high civilization. (3) 
People of European races are today maintaining and developing 
a high civilization in relatively unstimulating climates such as 
that of northern Australia. Each of these objections is highly 
significant and must receive careful attention. The first will 
form the subject of the present chapter. 

In a series of books, among which The Pulse of Asia, Pales- 
tine and Its Transformation, and Climatic Changes are the 
most important, I have set forth the hypothesis that during 
historic times the earth's climate has been subject to pulsatory 
changes. It cannot be too clearly understood that this hypothe- 
sis was not framed with reference to the hypothesis of civiliza- 
tion and climate presented in this book. It was developed inde- 
pendently before I realized how closely the distribution of civi- 
lization is bound up with that of climate. In fact, the hypothesis 
of climatic changes was what led originally to the studies de- 
scribed in this book. 


The steps which have led to this hypothesis may be summed 
up as follows : In many parts of Asia, Africa, and America ruins 
of towns and cities are located where now the supply of water 
seems utterly inadequate. Old strands surround lakes that are 
now dry ; old alluvial terraces in which lie remains of human 
occupation show that the rivers have changed their habits of 
erosion and deposition since men began to become civilized. Old 
roads traverse deserts where caravans cannot now travel ; traces 
of dry springs are seen; bridges span channels which carry no 
water for years at a time ; old fields are walled and terraced in 
places where now the rainfall is too scanty to permit agriculture 
and where no water can be brought for irrigation. Elsewhere old 
irrigation canals abound in districts where today there is little 
or no water supply, or where what water there may be in the 
streams is so salty that it kills the crops instead of invigorating 
them. These things and many others, which almost every traveler 
in semiarid or desert countries has seen for himself, seem to be 
almost irrefutable evidence that at some time the climate was 
moister than now. 

Such evidence long ago gave rise to two hypotheses, which are 
now almost abandoned, those of deforestation and of progressive 
desiccation. According to supporters of the first hypothesis, the 
reckless cutting of forests has not only allowed the rains to 
denude the mountain sides of soil, but has caused an actual 
diminution in rainfall. This view once had a considerable popu- 
lar vogue, but for various reasons it has now practically ceased 
to be considered among scientists. In the first place, modern 
measurements of rainfall before and after the deforestation of 
large tracts are contradictory. At best they show only slight 
differences, too small to have any appreciable effect, and in prac- 
tically every case so doubtful that they may be due merely to 
the accident of an especially dry or rainy period of a few years 
coming not long before or after the forest was cut. Moreover, 
many of the strongest evidences of desiccation are found in 


places such as southeastern Syria where there is no reason to 
think that the country has ever been forested since it was first 
occupied by civilized man. Finally, there are thousands of square 
miles in Chinese Turkestan where the forests themselves have 
died because of lack of water, and are still standing as gaunt 
skeletons preserved for a thousand years or more because of the 
extreme dryness of the air. 

The hypothesis of progressive desiccation assumes that dur- 
ing historic times the earth has steadily been growing drier. 
This was my own view when I published Explorations in Turkes- 
tan in 1905. Many careful students still uphold it. The majority 
of its supporters, however, apparently think that it needs modi- 
fication along lines which will shortly appear. 

While evidence of more water in the past than at present is 
prominent in many places, there is also much of the contrary 
nature, less noticeable, but no less convincing. For example, 
ruins are located on the floor of lakes which must have been 
partially dry when the structures were erected. Elsewhere one 
finds irrigation canals in places now so damp that their con- 
struction would seem to be a waste of energy. In north Africa 
and Syria huge irrigation works are located in regions of 
another kind, which not only are dry now, but must have been 
dry in the past. Otherwise the Romans would not have expended 
such enormous labor to get water. These things and others 
furnish almost irrefutable evidence that at certain periods the 
water supply of many semiarid regions was no greater than at 
present. Because such evidence is less abundant and noticeable 
than the other kind, the believers in progressive desiccation 
have overlooked it. On the other hand, other students have been 
so impressed by it that they have held that there have been no 
changes of climate during historic times, and that the fluctua- 
tions which followed the last glacial epoch came to an end before 
the beginning of history. 

There seems only one way to reconcile these two opposing 


views, each of which is based on unassailable evidence. That 
way, as I first showed in The Pulse of Asia (1907), is to group 
the evidence according to its date, and see how far the indica- 
tions of moisture and aridity come at different times. For ex- 
ample, several lines of evidence, such as the location of dwellings 
in tracts that are now great swamps in Ireland, unusually pro- 
longed famines in China and western Asia, and vegetation of 
warmth-loving types in Europe suggest a dry period perhaps 
1400 to 1200 years before Christ. At the time of Herodotus, be- 
tween 400 and 500 B.C., all the evidence points to moist condi- 
tions in western Asia and northern Africa ; about 200 B.C. a 
somewhat drier climate apparently prevailed, although not so 
dry as now ; then at the time of Christ conditions were once more 
favorable. After about six centuries of gradually increasing 
aridity, a dry period more severe than that of 1200 B.C. reached 
its climax about 650 A.D. An improvement followed which cul- 
minated about 1000 A.D., then came another bad time, reaching 
its worst in the thirteenth century. It was followed by a rapid 
recovery, which did not last long enough to be of great value. 
Since the fourteenth century minor fluctuations have continued 
to take place. The whole matter is summed up in the dotted line 
of Figure 46. There the high parts of the curve represent moist 
conditions and the low dry. The curve is only approximate, and 
does not represent all the data now available, but it seems wise 
to reproduce it in the original form which it had when the "pulsa- 
tory hypothesis" of climatic changes was first formulated. 

From what has been said, it appears that during historic 
times climatic pulsations have taken place. They seem to be of 
essentially the same nature as glacial epochs and post-glacial 
stages, the difference being only in degree. Apparently, the con- 
ditions of the geological past merge without break into those of 
the present. This fact is rarely appreciated by historians and 
archaeologists, who naturally have little occasion to come in 
contact with it. Students of glaciation, however, have carried 


the matter so far that we now have abundant evidence of a great 
succession of climatic variations covering the entire period from 
the present time back to the date when ice covered much of the 
northern United States and Europe. They find no evidence of 
any sudden break between the past and the present. On the con- 
trary, by means of "varves" or layers of clay deposited each 
year in lakes that disappeared after the retreat of the ice, De 
Geer and Antevs, for example, find a constant series of pulsa- 
tions. In studying the retreat of the ice in North America, F. B. 
Taylor and others have discovered a series of some fifty small 
moraines indicating stages of retreat. These point to climatic 
cycles having an average duration of somewhere around five 
hundred years, although varying considerably. Most students 
of post-glacial climates believe that such cycles, on a diminish- 
ing scale, have continued into the historic period. 

In order to test the pulsatory hypothesis, some means of 
actually measuring the climate of the past seems necessary. In 
the southwestern United States there appear to have been 
changes like those in western Asia. In that region, Prof. A. E. 
Douglass has found that the thickness of the annual rings of 
trees furnishes a reliable indication of variations in the water 
supply from year to year. In California among the big trees I 
found that correlation coefficients for a period of about fifty 
years show clearly that the rainfall is a main determinant of 
the rate at which the trees form their rings of growth. Other 
factors of course enter into the matter, as Antevs has pointed 
out in a forthcoming publication of the Carnegie Institution of 
Washington. But these likewise are climatic. Corrections must 
be made to eliminate the effects of age, but this can be done by 
mathematical methods of considerable accuracy. It is difficult 
to determine whether the climate at the beginning and end of a 
tree's life was the same, but it is easy to determine whether there 
have been pulsations while the tree was making its growth. If 
the trees from various parts of a given district form thick rings 



for a century, then thin ones for another hundred years, and 
again thick ones, we may be almost sure that they have lived 
through a long period of unfavorable climate. 

During the years 1911 and 1912, under the auspices of the 
Carnegie Institution of Washington, I measured the thickness 
of the rings of growth on the stumps of about 450 Sequoia 
trees which had been cut for fence posts, shingles, and pencil 
wood in California. The trees varied from 250 to nearly 3250 
years of age. The great majority were over 1000 years old, 79 
over 2000, and 8 over 3000. Even where only a few trees are 
available, the record indicates the main fluctuations, although 

Figure 47. Changes of Climate in California for 2000 Years. Adjusted to 
Levels of Owens Lake. Dotted Lines Indicate Main Respects in Which 
Antevs' Method of Correction Gives a Different Result from That of 
the Author 

not the details. Where the number approximates 100, acci- 
dental variations are largely eliminated. Accordingly, in Cali- 
fornia we have a climatic record which is fairly accurate for 
2000 years and approximate for 1000 years more. This is 
expressed graphically in the solid line of Figure 46. In order to 
bring out the details the more reliable portion from 100 B.C. 
to the present time has been reproduced in Figure 47. This 
resembles the corresponding part of Figure 46, except that the 
vertical scale is three times as great, and corrections have been 
made on the basis of Owens Lake. 

In general, the tree curve resembles that of changes of cli- 
mate in Asia, although there are differences in detail. Beginning 


with 1000 B.C., both curves have a maximum. They dip down 
about 800 B.C., and rise high not far from 700. About 400 B.C. 
they disagree, but this is probably due largely to the absence of 
reliable data for the Asiatic curve. In the second century before 
Christ both are low, but not so low as at present; at the time 
of Christ they rise high, and continue to fluctuate together till 
300 A.D. At that time they show a difference which may have 
arisen because I was unduly impressed by the abandonment of 
many ruins in Chinese Turkestan at the end of the third century. 
The dash line is probably more accurate than the dotted and 
should be used. In the seventh century both curves reach their 
lowest point. Then, from 650 A.D. onward, their general course 
is closely similar, especially about 1000 A.D. In the tree curve 
the evidence of pulsations is even clearer than in the Asiatic 
curve. The general agreement between the two curves seems to 
indicate that the main climatic variations of western Asia and 
the region of similar climate in the United States are approxi- 
mately the same. Moreover, the fluctuations of both tree growth 
and rainfall among the Sierras during the last half century show 
a strong resemblance to those of rainfall in Palestine, as is set 
forth in Climatic Changes and in Post-glacial Climatic Cycles, 
a publication of the Carnegie Institution of Washington. Since 
the present growth of trees in California shows so close an agree- 
ment with the rainfall in western Asia, it is almost certain that 
a similar agreement existed in the past. The growth of the trees, 
with its pronounced variations lasting hundreds of years, is 
generally accepted as the strongest single piece of evidence that 
pronounced climatic pulsations have taken place in historic 
times. The agreement between the curve obtained from exact 
measurements in California and that obtained from physio- 
graphic and archaeological evidence in western Asia unites with 
present climatic variations in proving that these two regions of 
similar climatic type have experienced a similar series of climatic 


Another line of evidence in the western United States is pecu- 
liarly important because it employs a method absolutely differ- 
ent from those already mentioned, but reaches the same con- 
clusion. Every river holds in solution a certain amount of 
sodium, chlorine, calcium, carbon dioxide, and various other 
materials. Under ordinary circumstances this cannot be detected 
except by chemical analysis. If the river flows into a lake which 
has no outlet, however, the water is evaporated, but the dissolved 
constituents remain, and gradually increase until a brine is 
formed. Certain materials, such as the calcite, which forms tufa 
or other kinds of limestone, are removed by algae or bacteria, 
and certain others, such as potassium, seem to be absorbed by 
the clays of the lake bottoms. Sodium, and especially chlorine, 
however, do not appear to be removed until the brine becomes 
completely saturated so that crystals of common salt are formed. 
Hence, if we know the amount of sodium and chlorine brought in 
by the rivers each year and the amount dissolved in an unsatu- 
rated lake, we can easily calculate the time that has elapsed 
either since the lake was first formed, or since it last overflowed, 
A body of water that overflows, as everyone knows, soon becomes 
essentially as fresh as the rivers that supply it. 

On the eastern side of the Sierra Nevada mountains Owens 
Lake, a body of salt water in southern California, is peculiarly 
well adapted to our present purpose. Owens Lake receives most 
of its water from the river of the same name. Both have been 
measured and analyzed with unusual thoroughness because part 
of the river is carried to Los Angeles in a remarkable aqueduct 
nearly 250 miles long. H. S. Gale of the United States Geological 
Survey has carefully gathered all the available data. He con- 
cludes that, according to the figures of the aqueduct engineers, 
the accumulation of the chlorine of Owens Lake would require 
4200 years, and the sodium 3500, the average being 3850. A 
series of fresh strands and an old outlet channel show clearly 
that the lake overflowed not long ago. Hence, Gale concludes 


that "4000 years or considerably less" is the length of time 
since the lake stood at the outlet level, 180 or 190 feet higher 
than at present. These figures, however, require modification. 
The reason why Gale gives the period as "4000 years or con- 
siderably less" is that the figures of the engineers omit the lower 
third of the drainage area of Owens Lake, and this is the part 
where the waters flow most slowly and where the clays and other 
deposits which surround them are most saline. Hence, more salt 
proportionately should be accumulated here than higher up. 
Moreover, as he carefully points out, no allowance is made for 
the well-ascertained fact that when the rivers are more abun- 
dantly supplied with water, as must have been the case when 
the lake was full, the amount of dissolved salt is also greater 
although not in direct ratio to the water supply. When due 
allowance is made for these conditions and for others of minor 
importance, the time since the last overflow is reduced to 2500 
or 2000 years. In other words, at the time of Herodotus and 
perhaps at the beginning of the Christian era, the climate of the 
Owens Lake region was so moist that the lake expanded to two 
and one half times its present size and sent a stream down the 
outlet channel. 

Owens Lake does more than indicate a change of climate 
within two or three thousand years. It also shows that the change 
has been highly irregular. This is proved by a large number of 
strands lying below the level of the outlets, and by the way in 
which these vary in character and in the extent to which they 
have been covered by fresh detritus washed down from the moun- 
tains. At Owens Lake there are four series of strands. These 
apparently correspond to the four chief periods when the cli- 
mate has grown moist as shown by the growth of the big trees 
in Figure 47. Fortunately, Owens Lake lies only fifty miles east 
of the region where the trees were measured. The general cli- 
matic fluctuations of both districts are the same. The uppermost 
strand, the huge gravel beach at the level of the outlet, was pre- 


suniably last reached by the water about the time of Christ, or 
possibly in the days of Herodotus, for both the chemical evi- 
dence and the trees point to this conclusion. A series of similar, 
but much smaller beaches at lower levels record the approach of 
a dry period during which the lake fell to a low level whose exact 
position cannot be determined. Judging by the trees this must 
have culminated about 650 A.D. During this period gravels were 
washed in by mountain streams and formed what are known 
as fans, or low, flattened cones, which may be several miles long. 
These covered the old strands in many places, and extended far 
below their level to the diminished lake. 

Next the waters rose again, but not halfway to their former 
level. They formed two small strands, not gravelly like their 
predecessors, but faint and sandy as if the winds were weak. 
They must date from about 1000 A.D., when the trees indicate 
a wet period, for they are younger than the gravel fans of the 
preceding dry time. The next phase of the lake was a dry period, 
which was most extreme about 1250 A.D. More gravels were 
then deposited, and the fact that they cover the preceding 
strands and extend to a much lower level shows that the lake 
then stood low, as would be expected from the trees. 

The next high period of the lake, about 1350 A.D. according 
to the trees, is unusually interesting. The water did not reach 
so high a level as formerly, perhaps because the rainy period was 
short, but it formed a large beach of gravel quite different from 
the preceding beaches. This seems to indicate great storminess, 
a condition which is also suggested by the fact that the growth 
of the trees at this time increased more rapidly than at any other 
period for nearly 3000 years. In Europe during the same cen- 
tury, unprecedented storms caused great floods in France, while 
the severity of the waves was so intense as to break through 
beaches and sand dunes, and convert large marshy areas into 
portions of the sea along the coasts of Holland and Lincoln- 
shire. During the winters the rivers froze to an unheard-of 


degree, and three or four times men and animals passed from 
Germany to Sweden on the solid ice of the Baltic Sea, an occur- 
rence unknown in our day. In England the summers were so 
rainy that the average yield of grain diminished disastrously. 
In self-defense many landowners gave up grain-raising, and 
turned their attention to sheep and cattle. Distress and discon- 
tent were the inevitable result among the peasants. Far away in 
central Asia the Caspian Sea and the lake of Lop Nor both 
rose with great rapidity between 1300 and 1350 A.D. Thus from 
California to China evidence of various kinds unites to indicate 
that during the fourteenth century there occurred a short 
period of unusual storminess. Such conditions, if intensified and 
prolonged, would probably cause the accumulation of enormous 

To return to Owens Lake, the lowest series of strands is sandy 
and small compared with the large gravel bar of 1350, and was 
evidently formed under different conditions. Presumably the 
lake fell to a low level about 1500 A.D., and rose during the next 
century or more to form the highest strand of the latest series. 
The evidence of Owens Lake is much strengthened by that of its 
neighbors. At Mono Lake farther north in California, the more 
recent strands are almost identical with those at Owens. Since 
1900 Mono Lake appears to have risen higher than at any time 
since at least 1775, as we judge from the rings of growth of a 
tree killed by the rising salt water. Thus on all sides there is 
the strongest evidence not only that the climate of the past 
differed from that of the present, but that many minor pulsa- 
tions have occurred, and have grown less intense during the 
historic period. 

Up to about 1912 I supposed, as did practically all students 
of the subject, that the same kind of climatic changes have 
taken place in all parts of the world. At that time Penck, a 
leading student of the glacial period, came to the conclusion 
that this is by no means the case. He showed that on the north- 


ern side of arid or desert areas we find densely saline lakes, like 
Great Salt Lake in Utah, surrounded by old strands. These 
indicate that the lakes have long been contracting, so that they 
have abandoned first one strand and then another, while at the 
same time their water has become more and more highly concen- 
trated. On the equatorial side of the desert belt, on the contrary, 
we have such lakes as Chad in Africa, a shallow sheet of water, 
only slightly salty and not surrounded by any great series of 
strands. It has the appearance of being a new lake formed by a 
recent increase in rainfall. Penck points out a similar contrast 
between the sand dunes on the poleward and equatorward sides 
of the desert belt in both hemispheres. On the poleward side, the 
dunes consist of loose, moving sand appropriate to places that 
are growing drier. On the other side there are plenty of dunes, 
but they are covered with a sparse vegetation which is sufficient 
to keep them from moving and to prevent the formation of new 
dunes. Since their formation, the rainfall has evidently in- 
creased. From the dunes and lakes, as well as from other evi- 
dence, such as the snowline, Penck concludes that changes of 
climate consist of an alternate shifting of the climatic zones. 
During a glacial period he holds that the northern storm belt is 
shifted southward so that the storminess of Germany and the 
northern United States is pushed into Italy or the southern 
United States. In the same way the desert belt is displaced 
toward the equator. Thus the polar side of the desert has 
more storminess and moisture than formerly, while on the equa- 
torial side the desert is shoved into an area where equatorial 
rains formerly supported abundant vegetation. During a time 
such as the present, on the contrary, the desert expands on its 
northern border. Its lakes diminish, leaving strands behind them 
and becoming very saline ; vegetation dies ; and the wind is free 
to pile up sand dunes. On the other, or equatorial side of the 
desert, the amount of rain is greater than before. Hence, basins 
which formerly contained no water are now filled with shallow 


lakes, such as Chad, which have not yet had time to become 
highly saline. Vegetation also spreads into the desert and sand 
dunes become covered with it and cease to be moved by the wind. 
Few people have studied glacial problems more carefully than 
Penck. One result of the minuteness and care of his studies is 
that he is one of the foremost advocates of great climatic com- 
plexity. He distinguishes several post-glacial stages, and in 
addition brings his conclusions so far toward our own time that 
he states that a peculiarly dry period prevailed in central Asia 
as late as the early part of our era. 

While Penck was formulating his hypothesis of a shifting 
of climatic zones as an explanation of the glacial period, I was 
working out the same hypothesis in respect to historic times. 
Our work was wholly independent, being based on different lines 
of evidence, and, so far as I am aware, neither knew what the 
other was doing. The shifting of climatic zones is by no means 
a new idea, for it has been vaguely suggested many times. The 
new thing is to find direct evidence of it, such as Penck presents 
in his discussion of lakes and dunes. As to historic times, the 
ruins of Guatemala and Yucatan furnish perhaps the best avail- 
able test, for those regions are the most notable example of a 
civilization which developed within the torrid zone. The ruins of 
that civilization are the most remarkable archaeological remains 
in the western hemisphere. Part lie near the northern coast of 
Yucatan in a relatively dry region inhabited today by a fairly 
prosperous agricultural population. Many of the finest ruins, 
however, and most of the more ancient ones, lie back from the 
coast in a wilderness of dense forest and jungle. There agri- 
culture is almost impossible. The difficulty of clearing the rank 
vegetation and getting it dry enough to burn before a new crop 
of lusty bushes grows up is enormous. Fevers, too, prevail 
most of the year. They include the worst types of tropical 
malaria, as well as many other kinds. Foreigners are quickly 
attacked, and it would be dangerous for a white man to attempt 


to live there permanently, even with all the appliances of modern 
medical science. The natives also suffer terribly. Many of the 
children are apparently killed by malaria and other tropical dis- 
eases in infancy. Those who grow up carry the effects with them 
through life. Seventy-five per cent of the tropical workers at 
the Panama Canal are thought to have had malaria germs in 
their systems, even though they did not show outward signs of 
the disease, and the case is probably even worse among the 
natives of the lowland forests of Quintana Roo, Campeche, and 
Peten, where most of the early Maya ruins are located. One has 
only to look at their swollen paunches to see that something is 
the matter ; and their dull, apathetic manner, both in work and 
play, is another sign of some deep-seated physical ailment. 

Here, where today the Indians are so diseased and agricul- 
ture is so difficult, there dwelt an ancient race characterized by 
the qualities which we have defined as most essential to a high 
civilization. The Mayas of Yucatan and Guatemala, alone 
among the aborigines of America, carried to high perfection 
the arts of sculpture and architecture. The Incas of Peru, to 
be sure, made striking buildings, but they had no idea how to 
adorn their simple structures with columns, rosettes, arches, 
gargoyles, pediments, and many other architectural devices 
which were universal among the Mayas. These clever people 
were also adepts in astronomy, for they framed the most exact 
calendar ever known except our own. Theirs was better than 
that which eastern Europe used up to the time of the Great War. 
Most remarkable of all, the Mayas developed the art of writing 
and carried it to a pitch higher than that reached by the Chinese, 
for they apparently began to use signs to denote sounds instead 
of having a sign for each individual word. Their temples are 
great structures which sometimes rise three stories in height and 
have a length of three or four hundred feet. A single city often 
contained a score of noble buildings and extended over many 
square miles of territory. The Mayas need not shrink from com- 


parison with any people who had no greater opportunities. They 
were terribly hampered in many ways. They were not blessed 
with progressive neighbors to spur them on and teach them new 
ways. They had no beasts of burden. They could not plough the 
fields, nor transport loads except by their own labor. Every one 
of the great stones which form their temples and palaces must 
have been brought by human effort, a task which none but a 
most energetic race would undertake. Another disadvantage was 
the absence of metal tools. The Mayas perhaps had a little 
copper, but not a trace has been found of any metal tool that 
would be of service in carving their intricate f a9ades and deli- 
cately wrought statues. Flint or obsidian was all that they had, 
and yet with such poor tools they created works of art which 
command sincere admiration. To do all this with such small 
opportunities was surely one of the greatest feats ever achieved 
by any race. 

The most surprising thing about the Mayas is that they 
developed their high civilization in what are now the hot, damp, 
malarial lowlands where agriculture is practically impossible. 
A hundred miles away on the coasts of Yucatan or in the Guate- 
malan highlands far more favorable conditions now prevail. 
There agriculture is comparatively easy, the climate, while not 
bracing, is at least good for the torrid zone, and malarial fevers 
are rare. Today the main cities lie in these more favorable re- 
gions ; the energetic part of the population is there, and the in- 
terior lowlands are hated and shunned by all except a degraded 
handful. In the past the more favorable localities were occupied 
by people close akin to the Mayas, yet civilization never rose to 
any great height. Ruins are found there, but they are as far 
behind those of the lowlands as the cities of Yucatan are today 
behind those of the United States. 

In explanation of these peculiar conditions several possi- 
bilities suggest themselves. First, we may suppose that the 
Mayas were the most remarkable people who ever lived. They 


were able to carry on agriculture under conditions with which 
no modern people, not even those of European race, have ever 
succeeded in coping. They chose the worst place they could 
find, almost the worst in any part of America, even though far 
better places lay close at hand and were occupied by an allied 
people relatively few in numbers and backward in civilization. 
They were able to preserve their energy for a thousand years or 
more under the most debilitating climatic conditions ; and, lastly, 
they were immune to the many fevers which today weaken the 
dwellers in their old habitat. It is possible that a process of 
natural selection had given these people an extraordinary degree 
of genius, energy, and ability to combat disease. Indeed, it seems 
to me that this must have been the case. Nevertheless, I doubt 
whether it fully explains why the Mayas settled and thrived in 
what now would generally be accounted the worst parts of their 
general region. A second possibility is that in the time of the 
Mayas tropical diseases were less harmful than at present. We 
have no shred of evidence one way or the other. Such a thing is 
possible, but in view of the fact that there are several kinds of 
malaria, not to mention other diseases, any one of which greatly 
weakens a race, there is little chance that the Mayas were free 
from disease unless something else was also different. Even if 
diseases were not so prevalent as now, this does not explain the 
other apparent anomalies of the Maya situation. It may be, 
however, that a fairly satisfactory explanation will be found if 
the two preceding possibilities are joined with a third, namely, 
a climatic change such that the dry conditions which prevail a 
little farther north prevailed in the Maya region when these 
people attained eminence. Such a shifting of zones would increase 
the length of the dry season which now comes in February and 
March. This would diminish the amount of vegetation and cause 
scrub to take the place of dense forest. Under such conditions 
agriculture would become comparatively easy. Fevers would 
also greatly diminish, for in the drier parts of Yucatan they 


are today relatively mild, and the lowland plain would be the 
natural site of the chief development of civilization just as is 
the case in other countries. 

When the dates of Maya history are compared with the curve 
of tree growth in California, they seem to agree with the hy- 
pothesis of a shifting of climatic zones. The early chronology 
is so doubtful that we may pass it by. The seventh century, 
however, is known to have been a time when Maya civilization 
sank to a very low ebb, for scarcely a building dates from that 
time, and the traditions become most vague. The great fact of 
this period is that for some reason the Mayas completely aban- 
doned their old homes in what is now the forested south of 
Mayaland. They migrated north to the drier, less forested, and 
more healthful region of northern Yucatan. This would be what 
we should expect, for when the California trees grew slowly, as 
in the seventh century, the desert zone that almost girdles the 
globe would lie far to the north. At the same time the equatorial 
zone of rains would expand northward over Guatemala and 
Yucatan; the rainfall would be abundant and the dry season 
short ; the forests would become rank, agriculture would be 
difficult; disease would be rife; and the vitality of the Mayas 
would be sapped. From about 900 A.D. to 1100 A.D., on the other 
hand, the California trees grew rapidly. At such a time the desert 
belt would be pushed south, and favorable conditions would pre- 
vail in the home of the Mayas. At that time occurred the last 
great revival of architecture and the construction of the great 
buildings whose ruins now adorn Yucatan. Whatever the cause, 
there is no doubt that there was a marked outburst of energy. 
The later history of the Mayas has no great abundance of archi- 
tectural monuments to serve as landmarks, and hence cannot be 
correlated with the fluctuations of the California curve. Yet, 
so far as the indications enable us to judge, the two sets of 
phenomena are in harmony. 

In addition to the Maya ruins, the conditions of Palestine 


and the growth of the California trees furnish independent evi- 
dence that the zone of cyclonic storms has at certain periods 
suffered a shift equatorward. In Palestine, the rainy zone ap- 
parently once extended at least fifty miles south of its present 
limit, in spite of the fact that the mountains there die out and 
thus render the conditions doubly unfavorable to rainfall. Today 
Hebron is the last large town and Beersheba the last village. In 
the old days, Aujeh, far to the south, was comparable to Hebron, 
and other ruins indicate that settlements were located still 
farther southward. The California trees indicate a shifting of 
zones, because they grow most rapidly during years when storms 
continue late into the spring. At such times the winter zone of 
storms is pushed equatorward and continues to give moisture 
late in the spring. 

Further consideration of changes of climate is not here pos- 
sible. For that the reader must turn to Climatic Changes and 
Earth and Sun. Here our main interest centers in the results of 
such changes, and in the degree of certainty with which we can 
make use of them in the interpretation of history. For our pres- 
ent purpose the essential point is that a series of climatic pulsa- 
tions has apparently continued from a maximum phase in the 
last glacial epoch down to a minimum phase today. Nowhere do 
we find any marked break between the past and the present. On 
the whole, the early milleniums of the historic period appear to 
have been drier than the present in such regions as Syria and 
California, but this general condition of more abundant rain 
appears to have been broken by frequent dry periods which 
may have lasted hundreds of years. Some of these, as in the 
seventh century of the Christian era, may have been even drier 
than the present. Moreover, the effect of any given phase of a 
climatic pulsation is not the same in all parts of the world. On 
the contrary, the effects differ from zone to zone, from the coast 
of a continent to the interior, and from the east side to the west. 
Except in magnitude the climatic cycles of the past appear to 


have been like the small cycles of the present. California, for 
example, tends to be rainy when Florida is dry. 

It must be clearly understood that the chief characteristic of 
the climatic pulsations of the historic period has not been 
changes of temperature. Failure to understand this point has 
led to many mistakes. The chief variations have apparently oc- 
curred in the number, intensity, and paths of the kind of 
cyclonic storms which bring ordinary changes of weather in 
the progressive regions of the United States and Europe. Such 
storms are by far the most variable climatic factor. The extent 
to which the mean annual temperature or relative humidity of a 
region may vary from one year to another is very limited, but 
the rainfall, and still more the number of storm tracks whose 
centers pass near a given place, may vary greatly. Some years 
storm after storm sweeps across the country at intervals of 
only a few days, while in others a real storm occurs scarcely 
more than once a month. Even in a place like New York City 
where the climate is very regular, the number of storm tracks 
whose centers passed within 200 miles of the city in the short 
period from 1900 to 1915 varied from 21 in 1903 to 48 in 1915, 
while from July to December the variation was from 7 to 24. In 
regions having the type of climate now found in the eastern 
Mediterranean region and in California, such variations are 
far greater. At San Francisco, for example, the number of storm 
centers passing within 200 miles of the city during this same 
period varied from one in 1900, 1904, and 1914, or none in the 
twelve months from December, 1913, to November, 1914, to 
13 in 1903. In the past, according to our hypothesis, the number 
of storm tracks for century after century approached this 
higher figure, while at other periods it fell toward the lower 
figures. In other latitudes and in parts of the continents where 
other types of climate prevailed, an opposite type of change took 
place, while in intermediate regions no distinct alternation was 


CHANGES of climate are so vital an element in the main 
conclusions of this book, that I shall devote a chapter to 
criticisms of climatic hypotheses. I shall begin by summarizing 
once more the changes in my own opinions, for these changes 
have had much to do with the nature of the criticisms. 

1. When I first became convinced that climatic changes had 
taken place in historic times in western Asia I accepted without 
question an opinion then somewhat widely held that the earth 
as a whole was growing drier and warmer. 

2. Further study, as already explained, soon led me to aban- 
don this idea of progressive desiccation in favor of the hypothe- 
sis of pulsations whereby the climate first became warmer and 
drier, and then moister and cooler. 

3. The next step was the conclusion that variations in tem- 
perature are of negligible importance, and that the main change 
has been in the amount of rainfall. 

4. Investigations in regions other than deserts advanced the 
hypothesis another step by leading to the conclusion that 
changes of opposite types have taken place in different latitudes, 
and even on opposite sides of a continent in the same latitude. 

5. The last step was the conviction that the evidence points 
clearly to changes in the location, number, and intensity of 
cyclonic storms as the main factor in climatic pulsations. 

Bearing in mind, then, that the hypothesis of climatic pulsa- 
tions as presented in this book has become quite different from 
what it was when first published in 1905, let us consider some 
of the main criticisms. 


1. Many authors have endeavored to disprove all theories of 
climatic change during historic times by suggesting that the 
supposed evidences of moisture in the past are purely accidental. 
In one place, so they say, a river may have changed its course ; 
in another an earthquake may have diverted an underground 
water supply ; famous marches like that of Alexander with his 
elephants in Persia may have been possible not because the cli- 
mate was moister than that of today, but because the march 
occurred in an unusually wet year. In the same way the thou- 
sands of seemingly waterless ruins in the southwestern United 
States may all have depended upon hidden springs, one or two 
of which have been found. Such arguments are of value merely 
as guides in determining the kind of investigations that shall 
be made in the field. They break down when it is realized that 
although many conscientious investigators have had them in 
mind, the evidence that would give them weight is not forth- 
coming. It must be remembered that the evidence on which the 
hypothesis of climatic pulsations is founded is of many types ; 
it is widely spread in at least four continents ; and it depends 
upon literally thousands of ruined towns, waterless roads, aban- 
doned irrigation systems, old unirrigated fields now too dry for 
cultivation, old records of lake levels and the like. It is statisti- 
cally impossible that so many accidents should all point in the 
same direction. Accidents by their very nature tend some- 
times in one direction and sometimes in another. The evidence 
of climatic changes, however, is not only widespread, but ex- 
tremely systematic. At certain periods and in certain types 
of climate it all, so far as I can see, tends to indicate aridity. 
In other types of climate and at other periods it seems to point 
with equal unanimity in the other direction. If the evidence 
were merely the result of accidents, such a separation on the 
basis of both time and place would be impossible. 

2. A number of persons have criticized the pulsatory hy- 
pothesis under a misapprehension, or have directed their criti- 


cisms at earlier statements of the hypothesis without knowing of 
later modifications. A good instance of this is Woeikof's book 
on Turkestan. Apparently that Russian author had not read 
or had failed to understand The Pulse of Asia, but had become 
thoroughly familiar with a book written by his countryman, 
Berg, for the express purpose of combating what he believed to 
be the false conclusions of The Pulse of Asia. At any rate, 
Woeikof pronounced the conclusions of that book "inane," and 
then proceeds to prove the very thing that led to the choice of 
its title, namely, that during historical times the Caspian Sea 
and other lakes in central Asia indicate alternating periods of 
more and of less rainfall than at present. Herbette, a French 
critic, also aims his main arguments at progressive climatic 
changes, but agrees that the Caspian Sea affords unmistakable 
evidence of climatic pulsations. In general, the critics have 
tended to attack not only the idea of a progressive climatic 
change in one direction during historic times, but the idea of 
climatic uniformity. The alternative to which almost all authori- 
ties turn is climatic pulsations having a greater intensity in the 
past than at present. Over nine tenths of the geographers of 
America, if we may judge from the fifty whose opinions have 
been expressed in writing, hold this view, although they differ 
as to the degree to which climatic pulsations have influenced 

3. A certain type of critic has asserted again and again that 
in the southwestern United States, and to a less degree in other 
places, the population in regions that are now too dry to sup- 
port many people was never so dense as the ruins seem to indi- 
cate. What really happened, they say, is that the same people 
built village after village and house after house. Superstitious 
fears of death or disease, or a tendency to wander may have 
caused a house to be inhabited for a few decades and then aban- 
doned. The old house never was reoccupied, but a new one was 
built by its side. Thus ruins which appear to be large enough 


for a thousand people may never have been occupied by more 
than fifty or one hundred at any one time. Wherever the history 
of a region is well known this explanation is wholly out of the 
question, as in Syria, the Libyan desert, Persia, and many other 
parts of the Old World. It has flourished in America simply 
because the history of pre-Columbian America is unwritten, and 
archaeologists have been free to exercise their imaginations. 
Douglass, however, who perfected the methods of measuring 
climate by means of tree growth, has most effectively proved 
that in at least one case a relatively large set of ruins was all 
built at practically the same time. By comparing the rings of 
different trees he is able to tell just which ring in one tree is 
synchronous with a given ring in another. This is possible be- 
cause the rings vary greatly from year to year, and the same 
succession of rings of various thicknesses is practically never re- 
peated. By this method Douglass finds that in one of the large 
ruins at Chaco Canyon, New Mexico, the houses were all con- 
structed within about a decade. Thus the whole village must have 
been occupied at one time and there was no successive addition of 
new rooms to replace those no longer occupied. Of course this is 
only one instance, but a single concrete, well-established fact like 
this is worth more than any amount of supposition. 

4. In many quarters there has been an assumption that cli- 
matic uniformity is a normal condition. Meteorologists do in- 
deed find that so far as records are yet available, which means 
for scarcely a century, there are no certain indications of 
progressive climatic changes. But there is overwhelming evidence 
of pulsations which increase in magnitude and duration as the 
records become longer. In the same way the geological record 
continually discloses new evidence of climatic pulsations. Where 
one glacial period consisting of a single epoch was generally 
recognized half a century ago, at least six are now recognized. 
These date from all parts of geological time, and some have 
several epochs and subepochs. Moreover, the studies of Bar- 


rell, De Geer, Sayles, and many others are rapidly showing that 
during practically the whole of the earth's known history smaller 
climatic variations have occurred. Thus pulsations of climate 
are now almost universally regarded as characteristic of the 
vast periods covered by geology as well as of the short period 
covered by exact climatic records. The presumption is that 
similar pulsations of intermediate magnitude were characteristic 
of the intervening historical period. 

One of the most interesting facts in this connection is the 
change of attitude among meteorologists. For example, Ward 
of Harvard, who was for many years the only professor of 
climatology in an American university, has long been one of the 
strongest champions of climatic uniformity. In his later works, 
however, and especially in his forthcoming Climate of the United 
States, his attitude toward the hypothesis of pulsatory climatic 
changes has altered from pronounced opposition to benevolent 
neutrality. His position is that the kind of physiographic and 
archaeological evidence which must be used in solving the problem 
of climatic changes during the period prior to exact records is 
utterly different from the statistical data to which climatolo- 
gists and meteorologists are accustomed. Therefore specialists 
of those types cannot properly evaluate it, but must wait for the 
final decision of specialists in this particular line. As a matter 
of fact, the great majority of specialists in post-glacial clima- 
tology now accept the idea that climatic pulsations have con- 
tinued into historic times. 

5. The most important criticism of my climatic hypotheses 
that has yet appeared was written by J. W. Gregory,* a British 
geographer who has traveled very widely. He makes two im- 
portant points, but both pertain to matters where I had already 
come to the selfsame conclusion which he advocates. His first 
point is that various types of vegetation, such as the palm tree, 
grew in places like Palestine in the past and grow there today. 

* "Is the Earth Drying Up?" Geographical Journal, vol. 43, 1914. 


This, he says, precludes a change of climate, for if Palestine 
were colder two thousand years ago than now, the palm could 
not have flourished. The truth of this statement is undeniable 
if we are talking about pronounced changes in the mean tem- 
perature. As I have already shown, however, the evidence points 
toward changes of precipitation much more than of tempera- 
ture. The best students of glaciation agree that during the 
glacial period the mean temperature of the earth as a whole 
was probably not more than 10 or 15 F. cooler than at pres- 
ent. If the climate at the time of Christ differed from that of 
the present time by one tenth of the difference between our 
modern climate and that of the glacial period, the temperature 
of Palestine would only have to be about 1 F. cooler than now. 
That would scarcely produce any appreciable effect upon vegeta- 
tion. The actual figures show that Palestine might be at least 2 
or 3 F. colder than now without preventing the growth of the 
palm tree. Moreover, the extremes may have been greater than 
at present without much change in the average temperature. If 
the winter storms were colder than now by a few degrees, that 
would not hurt the palm tree. In Seistan in eastern Persia I 
have camped in six or eight inches of snow almost under the 
shade of a palm grove whose dates, packed in a sheepskin, were 
uncommonly delicious. The thermometer fell below 20 F., and 
a strong north wind overturned the tent, but the palm trees did 
not suffer, for in two or three days the air was again as balmy 
as spring. So far as has yet been shown, the conditions of vege- 
tation nowhere seem to be out of harmony with our hypothesis. 
Gregory's other point, like the one already discussed, agrees 
completely with a conclusion to which I had been led inde- 
pendently. He shows that so far as there is evidence of climatic 
changes, it points in one direction in some regions and in the op- 
posite direction elsewhere. He even published a map showing the 
distribution of positive and negative changes. Inasmuch as this 
conclusion agrees with that to which both Penck and myself 


had been led on entirely different evidence at essentially the 
same time, I see no reason to question it. In a word, the article 
by Gregory, which some historians have regarded as demon- 
strating that there have been no changes of climate, goes far 
toward substantiating the hypothesis of this book, for it helps 
to clear up some of the main difficulties. It does not touch at all 
upon the problem of pulsations. Like practically every other 
important criticism of my conclusions it was published while 
the pulsatory hypothesis was still being developed and before 
the most convincing evidence, that of the Big Trees, had been 
published in The Climatic Factor. Since the publication of that 
book, so far as I am aware, there has been no serious quantita- 
tive attempt to disapprove the general hypothesis of climatic 
pulsations during historic times. 

6. The contrast in the types of evidence which are conclusive 
to workers in diverse lines of research is illustrated not only 
by the fact that meteorologists are slow to accept the evidence 
of historic changes of climate, while geologists are quite ready 
to accept it, but by the fact that historians seem to think that 
if changes of climate have occurred there ought to be written 
records to this effect. This may be illustrated by two eminent 
geographers who follow the historical method. Brunhes and 
Seniple both reject the idea that climatic changes have had an 
important effect upon history, but neither gives reasons for 
such rejection. Miss Semple, for example., in an admirable paper 
on the Mediterranean lumber trade merely states that, having 
studied the evidence, she does nob think it convincing. Her work, 
with its remarkably complete references even when minor matters 
are discussed, shows that to her the real evidence on this point 
is the written word. With her usual fairness, however, she points 
out that the accounts of widespread forests in ancient Cyprus 
suggest a different climate. She also gives many other facts 
which seem much more consistent with climatic changes than 
with uniformity. At least, they seem so to persons with a geo- 


logical training. Such persons have become more and more accus- 
tomed not only to the idea of repeated climatic fluctuations of 
all grades throughout geological times, but to the idea that 
such fluctuations have caused the destruction of many types of 
plants and animals, and have hastened the development and mi- 
gration of new types. The historian, on the contrary, is accus- 
tomed to attribute almost everything to purely human action. 
Hence, in the absence of records to the contrary, he assumes 
that human causes are mainly responsible for such facts as de- 
forestation, changes in trade routes, the apparent drying up 
of sources of water, the abandonment of settlements in the drier 
parts of the world, and the migrations which so largely originate 
in dry regions. 

7. Closely connected with the preceding attitude of mind is 
a reason for the rejection of the hypothesis of climatic changes 
which has been advanced by some historians. They say that 
such changes are not needed in order to explain the historic 
facts. But this has nothing to do with the matter. The primary 
question is whether climatic changes have taken place during 
historic times. If they have taken place, the historian must per- 
force take note of them and inquire into their effect, just as he 
inquires into the effect of barriers like the Alps or of great 
men like Socrates. This wholesome attitude is beginning to 
prevail in many quarters and will doubtless grow. 

A good example of the way in which a knowledge of climatic 
changes throws light on history is set forth by A. T. Clay in an 
article on "The So-called Fertile Crescent and Desert Bay."* 
From a study of Babylonian tablets Clay discovered that a 
Semitic people known as the Amaru or Amorites had already 
risen to a position of relatively high civilization in the fourth 
millennium B.C. Their capital was at Mari on the Euphrates 
River not far from 37 N. in the very heart of what the oriental 
historian Breasted has described as a "desert bay." The tablets 

* Journal American Oriental Society, 1924. 


seemed to show that this capital was powerful enough to rule 
Babylonia, but Breasted maintained that this was impossible 
because there was no sufficient "material basis" for an empire 
such as that of the Amorites. The arable land along the Eu- 
phrates is too limited to support an empire, and the surround- 
ing land is desert. Nevertheless Legrain of the University of 
Pennsylvania found a fragment of a dynastic list which showed 
beyond question that the Amorite city of Mari on the Euphrates 
ruled Babylonia in the fourth millennium B.C. Thus the historic 
facts and the present condition of climate are completely out of 
harmony. When Clay investigated the matter on the spot, he 
found about seven hundred square miles of arable land within 
the alluvial tract which might be watered from the Euphrates. 
Much of this, however, could not now be irrigated under the 
present conditions of floods and erosion. Even if it could all be 
irrigated it is scattered in so many small bits that it would form 
a very inadequate basis for an empire which could rule Baby- 
lonia. The region round about, however, is full of evidence that 
the country was by no means a desert in the past. As Clay puts 
it : "To include the Euphrates valley in the so-called 'desert 
bay' would be equivalent to including the Nile Valley in the 
Sahara desert, the difference, however, being that unlike the 
Sahara, Mesopotamia was not a desert in ancient times. 

"It is not improbable, since we know that the climate has 
changed within the past two thousand years, that practically 
the entire area of many thousand square miles of Mesopotamia 
north of the [Euphrates] river was fertile, or at least was a 
great pastoral territory. 

"The Khabur and the Balikh rivers, which flowed through 
this region southward to the Euphrates, were augmented by 
numerous streams, some of these at present containing water, 
while others are dry. Today the Balikh river at the end of 
summer is almost dry at its mouth. In commenting upon the 
Khabur and its tributaries an Arab writer says it is 'such as 


is not to be found in all the land of the Moslems for there are 
more than three hundred pure running fountains.' Certainly 
the Hebrew writers and redactors of the old Testament [would 
not have made] themselves ridiculous in the eyes of their in- 
telligent contemporaries by placing the Garden of Eden in this 
region, if it were a 'desert bay.' 

"And what is true of the region north of the Euphrates, is 
true of the land lying to the west of the river. There are dry 
beds of rivers and streams with sand and pebble bottoms in 
which, at present, water is not seen from one end of the year 
to the other; even many of these streams are spanned by well- 
constructed bridges. There are well-heads, spring houses, in 
which water formerly gushed from the earth, some even con- 
taining inscriptions; but where neither wells nor springs exist 
today. Even in the flat and once fertile plateau, which was 
thickly inhabited, there are no signs of irrigation having been 
practiced, showing that there was once sufficient rain to make 
the country habitable. 

"There are reasons for believing that forests existed in cer- 
tain regions, where today the tree and the vine could not secure 
a footing, for the hills are denuded of their soil. The land which 
the Greeks and the Romans found so profitable to develop, is 
now largely a waste ; and it is difficult to appreciate, from what 
we see at present, what certain ancient writers tell us about the 
land ; for example Cicero, who said that 'the country is so rich 
and so productive that in the fertility of its soil, and in the 
variety of its fruits, and in the vastness of its pasture lands, and 
in the multitude of all things which are matters of exploitation 
it is greatly superior to all other countries.' " (Manilian Law 

A little to the west of this upper Mesopotamian kingdom of 
Amaru, Butler points out that a pronounced change of climate 
is necessary in order to explain the history of Syria where an 
area of 20,000 square miles which is now practically "desert 


and deserted was more thickly populated than any area of 
similar dimensions in England or the United States is today if 
one excludes the immediate vicinity of the large modern cities. 
It has also been discovered that an enormous desert tract lying 
to the east of Palestine, stretching eastward and southward into 
the country which we know as Arabia, was also a densely popu- 
lated country. How far these settled regions extended in antiq- 
uity is still unknown, but the most distant explorations in these 
directions have failed to reach the end of ruins and other signs 
of former occupation." 

It would be easy to cite many other instances where a knowl- 
edge of climatic changes helps greatly in understanding history. 
In World Power and Evolution I have shown this in relation to 
Rome, while The Character of Races gives similar illustrations 
for China, Iceland, and other regions. But regardless of whether 
the historian feels the need of changes of climate to explain the 
historic record, no scientifically-minded historian can fail to 
take account of such changes if the specialists in such matters 
agree that they have taken place. The general attitude of such 
specialists, even in 1916, and still more at present, seems to be 
well summed up in the words of D. W. Johnson, professor of 
physiography in Columbia University. "The Climatic Factor," 
he says in a review of that book, "does not solve all the problems 
presented by a theory of climatic pulsations. It does not pretend 
to do so. It does aim to show that the evidence thus far available 
strongly supports the belief that there have been within historic 
time climatic changes of a pulsatory nature. In this the author 
has, in the opinion of the reviewer, been successful." 

One of the latest expressions of opinion is that of Aiitevs in 
Post-glacial Climatic Cycles (1924). "The view of distinct cli- 
matic fluctuations, advanced especially by Huntington in a 
number of papers, is being more and more accepted. The very 
best evidence of the occurrence of climatic fluctuations of short 
as well as long duration, up to thousands of years, is probably 


to be found in the varying rate of growth of the big trees and in 
the periodic retreat and halt of the edge of the Pleistocene ice- 
sheets. Huntington shows that there have been during historic 
times, within limited regions, climatic fluctuations of different 
length and character, but particularly in precipitation. The 
most noteworthy fact is that, especially in western and central 
Asia, the climate 2000 or 3000 years ago appears to have been 
distinctly moister than today." 


THE final stage of our investigation is now before us. We 
have compared the present distribution of civilization and 
of climatic energy, and have seen their remarkable similarity. 
We have found that during historic times a pulsatory shifting 
of climatic zones appears to have taken place. Let us now 
examine the shiftings of civilization, and determine how far they 
are in harmony with those of climatic energy. 

The black area of the map of energy, Figure 43, embraces 
about 1,100,000 square miles, or 2 per cent of the total land 
surface of the earth. Its population is about 260,000,000 or 17 
per cent of the world's total. Consider what would have hap- 
pened if all except this small 2 per cent of the lands had ceased 
to exist seventeen or eighteen centuries ago. Civilization would 
probably have been altered only slightly, although history 
would have been very different. If the rest of Europe had ceased 
to exist, Byzantine art, the works of the early Christian Fathers, 
Moorish architecture, and Spanish explorations, conquests, and 
colonization would be lacking. Yet this would not seriously 
change the conditions under which we now live. 

Suppose that not only the more backward European coun- 
tries, but all the rest of the world except the very high Euro- 
pean area had been blotted out in 200 A.D. The influence of 
Greece and Rome would have persisted in Italy. The Roman 
Church, the Renaissance, and the Reformation would all have 
played their part. The absence of new lands for discovery in 
the Middle Ages would doubtless have retarded the development 


of certain ideas. Otherwise the status of civilization would have 
been changed only a little. The United States is the only non- 
European country which has succeeded in touching the daily 
life of the world as a whole. American inventions have gone 
everywhere. The denizen of Turkestan who discusses news re- 
ceived by telegraph and whose wife makes his clothes with an 
American sewing machine is being genuinely touched by the 
New World. Yet America must not boast too loudly, for without 
her aid, Britain, France, Germany, Italy, and their small neigh- 
bors would have made most of the world's great inventions. To 
an even greater degree they would have been able to develop the 
arts and sciences. 

The energetic area of western and central Europe has been the 
great center of civilization for a thousand years. From it have 
gone forth more new ideas than from all the rest of the world 
combined. Its manufactures have flooded all parts of the earth. 
Politically it dominates about 60 per cent of the earth's surface. 
Socially its domination is still greater. The United States has 
long been chagrined because South America has looked to 
Europe not only commercially but for her inspiration in litera- 
ture, art, education, and almost every other phase of activity. 
Politically the United States helped greatly in inspiring the 
South American republics, and was at the front in stirring 
Japan to the new life of the last half -century. Yet those coun- 
tries have turned their faces Europeward, because that is where 
ideas have been most numerous and have been most fully em- 
bodied in the concrete form of institutions, inventions, or scien- 
tific principles. 

Wherever one turns, he feels the tentacles of the great Euro- 
pean center of civilization reaching out and vivifying the life of 
the whole world. To tell why this is so would require a volume. 
The position of western Europe, the strong racial inheritance 
of its people, their legacy from the civilizations of the past, 
their inspiring religion, their political freedom, and their many 


powerful institutions, all play an essential part. With these, 
however, and as one of the conditions which make them possible, 
stands the fact that western and central Europe is the only 
large region which for many centuries has had these advantages 
and at the same time has enjoyed a highly stimulating climate. 

The main American high area differs somewhat in shape on 
the maps of civilization and climate, but not essentially. In 
general, it occupies the portion of the United States lying 
north of about latitude 38 and east of the Rocky Moun- 
tains, together with the adjacent strip of southern Canada. Its 
area, taking the average of the black portions of the two maps, 
is approximately the same as that of the similar European 
region, that is, about 1,100,000 square miles. The population, 
however, is only 70 or 80 million. Here, then, we have another 2 
per cent of the earth's land surface, containing between 4 and 5 
per cent of the earth's total population. Consider how dispro- 
portionately great an influence it exercises. To be sure, it falls 
far behind Europe, but that is partly because it is newer and 
less densely populated. Yet it differs from Europe only in the 
degree, not the kind of influence. We have already referred to 
some of its inventions. All the world recognizes that the tele- 
phone and telegraph and many other forms of applying electri- 
cal energy are primarily American. In architecture we have 
evolved such wholly new types as the sky scraper. In art and 
literature we follow far in the wake of Europe. Yet we have 
done some things which are widely known in other countries, 
and which are steadily molding the world's opinion. The same 
is true in science, for the day is past when Europeans can ignore 
the work done on the western side of the Atlantic. In the future 
the disparity between Europe and America along this line bids 
fair to decrease rapidly, for great institutions devoted to pure 
science are growing on a scale unknown in other lands. 

This is in part the result of another line of effort in which 
Americans have achieved unusual success. By this I mean what is 


sometimes called "big business," the amalgamation of many 
minor industries or branches of an industry into one huge 
whole. It is illustrated in such organizations as our great rail- 
roads, and the United States Steel and Standard Oil companies. 
These represent in part the effect of unusual opportunities, but 
they also indicate a great expenditure of energy in planning 
and directing such widely ramifying activities. Lastly, and 
perhaps most important of all, the United States has touched 
the world upon the political and social side. In spite of political 
sins, which are many, this country has stood for freedom and 
justice. Its example has inspired other nations, including parts 
of western Europe, and has given them a stronger desire for 
equality of opportunity and for the breaking down of unfair 
discriminations between man and man. In more backward places 
a similar influence is felt. Good judges say that in Turkey, for 
example, one of the most potent causes of the revolution of 1908 
and the establishment of representative government was the 
teaching of American missionaries. The same is true in China, 
except that there the Americans have been associated with mis- 
sionaries of many other nations, while in Turkey they have 
been almost alone. In many other ways the ideas of this small 
area radiate in all directions. In that lies the essential point. 
Because this 4 or 5 per cent of the world's population are en- 
dowed with unusual energy, they are rapidly obtaining an in- 
fluence wholly disproportionate to their numbers. 

The third important region of high civilization and energy is 
Japan. Although the area is only about one tenth that of the 
corresponding portion of Europe and America, the population 
is over 50,000,000. In proportion to population, its influence 
upon the world is less than that of the European countries and 
the United States, which perhaps corresponds with an appar- 
ently lower degree of climatic energy. Yet we all recognize that 
Japan is a factor to be reckoned with. We admire its art and the 
skill and certainty with which the country has made use of our 


western civilization. We see students flocking thither from China. 
In India the news of the progress of Japan causes a stirring of 
dead leaves as by an autumn wind. As Japan has done, so India 
would do. In India, however, the agitators chiefly talk and com- 
mit violence, whereas in Japan they go to work quietly without 
much talk or violence and make themselves so efficient that they 
do not need the help of Europeans. When Japan sees an oppor- 
tunity, such as was afforded by the war in 1914, she takes it, 
and thus advances another step in her role as the most capable 
nation in Asia. Like Europe and America she makes mistakes 
sometimes, but they are the mistakes of strength more than of 

Next to Japan among our areas of high civilization comes 
JJew Zealand, together with the adjacent corner of Australia. 
Here we have chiefly a reflection of British civilization. Most 
of the five or six million people are grouped in an area some- 
what more than twice the size of Japan. The question is not 
whether they show evidences of a high civilization, which they 
certainly do, but whether they have added to the endowment of 
ideas and institutions with which they came from England. 
They have clearly done so, for when we think of Australia there 
come to mind such things as the Australian ballot, whereby a 
man is enabled to vote freely without undue influence from 
bystanders. We think also of progressive labor legislation, and 
of a pioneer attempt at old age pensions, especially in New 
Zealand. We are made conscious that these people are not 
mere followers, but are blessed with ideas which they themselves 
originate, and which spread out from them to other parts of the 

The last area which rises to the very high grade on the map 
of civilization is California and the coast farther north. The 
population is still relatively small, and the majority grew up 
in other regions. Hence, it is too soon to judge of the ultimate 
status of this area, It is so bound up with the rest of the United 


States and Canada that its particular contribution to civiliza- 
tion cannot be clearly differentiated. Yet, through their uni- 
versities and their readiness to attempt great things, the people 
of the Pacific coast impress the world as unusually capable and 
energetic. All together these five regions comprise less than one 
twentieth of the lands. Though they are densely populated 
because of the skill of their people in agriculture and manu- 
facture, they contain only about one fourth of the world's 
population. In influence, however, they many times outweigh the 
remaining three fourths. If they decide on anything the rest of 
the world must submit. They never care to imitate the more 
backward nations, whereas such nations show a growing desire 
to imitate Europe, the United States, or Japan. The reason 
seems to be that the favored one twentieth of the land is inhabited 
by people of great energy ; and this energy appears to be due, 
in part at least, to the frequency of cyclonic storms with their 
stimulating changes of weather from day to day. 

This leads to the question whether similar conditions pre- 
vailed in the past. Throughout the course of history there have 
been centers of civilization like those which exist today. One of 
the most important was the plain of Mesopotamia. Here, in the 
earliest days, the people of Sumer and Accad invented hiero- 
glyphs, founded great cities, built mighty irrigation works, 
drained the marshes, and laid the foundations of a complex 
system of law and religion. They clearly possessed the power of 
originating ideas and of putting them into effect in a way that 
is now characteristic of the modern centers of civilization. Where 
they originally came from we do not know, but apparently they 
were not Semitic. In course of time, they were overwhelmed by 
Semites who presumably came in as rude invaders. Then there 
happened one of the most characteristic events in the history of 
centers of civilization. The Semites dropped their old culture and 
adopted that of the people whom they had conquered. They 
began also to be inventive like their predecessors, and thus de- 


veloped cuneiform writing out of the hieroglyphics of the Su- 
merians. In later days, other Semitic invasions took place. In 
each case the invaders had done no great things in their original 
homes so far as we know, but when they came to Babylonia they 
blossomed into people of inventive minds full of new ideas which 
caused the arts to rise to higher and higher levels. Then the 
Semites were conquered by a non-Semitic race, the Scythians, 
who were also called Medes, and they in turn were stirred to great 
achievements. They were conquered by still another people, the 
Persians under Cyrus, and once more the old process of stimula- 
tion was repeated. 

One of the most significant things in Mesopotamian history 
is the way in which each invading race seems suddenly to have 
risen in civilization as soon as it reached the new country. How 
much of this was due to natural selection, whereby the weaker 
people among both the conquerors and the conquered were 
weeded out during the migrations, wars, and pestilences which 
preceded the final settlement; how much to contact with a 
higher civilization; how much to more abundant opportunities 
afforded by the new environment; and how much to a direct 
physical invigoration? I shall not try to answer these questions. 
That some of the invading races achieved great things because 
they possessed innate ability seems certain. That their minds 
were rendered more alert by contact with the achievements of 
the races which they conquered is likewise beyond doubt. That 
the wealth and agricultural possibilities of Mesopotamia and the 
abundance of labor stimulated the invaders to construct palaces 
and temples, build irrigation works, gather stores of treasure, 
carve huge monuments, spend money in supporting libraries 
and students, and carry on other great enterprises also seems 
certain. These principles are so firmly established that there is 
no need to discuss them. The question before us is simply 
whether there may also have been a climatic stimulus compa- 


rable to that which now seems so important according to our 
maps of civilization and energy. 

I do not purpose to discuss the empires of antiquity. I merely 
wish to point out some of the features of their location and his- 
tory which pertain to our main hypothesis. While Babylonia 
was flourishing, Egypt in the same latitude was also developing 
a great civilization. The two were rivals. Which rose higher it 
would be hard to say. They moved along parallel lines, and at 
last both fell during the same general period, although Egypt 
retained a moderate importance for some centuries after Meso- 
potamia had lapsed into insignificance. Far to the south the 
Sabseans in southwestern Arabia also developed a fairly high 
civilization, but they formed in no sense a great center. We know 
little about them, but apparently they were behind Mesopotamia 
and Egypt in the way that modern Bulgaria is behind England. 
Therefore, we may pass them by for the present although they 
will come up again in another connection. East of Mesopotamia 
the highlands of Persia were the seat of a comparatively high 
culture, but it scarcely rivaled that of the two great countries 
in the river valleys. Going on still farther toward the rising sun, 
we find high civilization in northern India, at a very early time. 
That region never rose to such a pitch as did the countries 
farther west, and it decayed somewhat earlier. Beyond India 
the chain of ancient empires is broken until we come to China. 
In Indo-China, to be sure, traces of a state of culture higher 
than that of today are found, but they belong to a compara- 
tively late date, and it is doubtful whether they were indigenous. 
They are important, but do not apply to the period now under 
discussion. China, however, stands in the same class with Egypt 
and Mesopotamia. It reached a high state of development about 
as long ago as they did. Here, too, the art of writing developed, 
inventions of many kinds were made, strong governments were 
organized, other powerful institutions were evolved, and in gen- 
eral there was intense mental activity. 


At this point the reader is advised to consult a map of Asia 
and Europe. Notice how the great countries of the past lie 
along an arc. They begin on the east with China, whose main 
center was north of the Yangtse basin. The civilization which 
flourished there possessed qualities like those of modern Europe 
and America. The Chinese were an aggressive, active people, able 
to fight or to evolve a new religious system as the case might be. 
The sword was in their hands not merely because those were 
ancient days, but because the people or their rulers wanted to 
make conquests, or because they were quick to resent infringe- 
ments of their rights. They were not like their modern successors 
who see themselves defrauded because they have not the power to 
cope with their despoilers. Follow the map westward along a 
band eight or ten degrees wide with the thirtieth parallel a little 
south of its center. At first we find ourselves among lofty moun- 
tains which merge into the great Tibetan plateau. Here we 
should not expect any great development because of the un- 
favorable topography. At length, however, our band descends to 
the plain of northern India. On the flank of the Himalayas lived 
Gautama, the great thinker who founded Buddhism. Out on the 
plains around Delhi and Agra and in surrounding regions was 
the home of the early Aryans, who developed the Sanscrit lan- 
guage, wrote the Vedas, and made a real contribution to human 
progress. Here, just as in China, a broad expanse of arable land 
was favorable to the development of a great people. Next our 
band strikes the high mountain rim of Baluchistan and Afghani- 
stan, and then passes over the plateaus of those countries, high 
and rugged in the north, lower and intensely desert in the south. 
In these regions the ancient civilization was higher than that 
of today, but not until we reach the western side of the plateau 
do we come upon the really advanced country of ancient Persia. 

As our band leaves the Persian highland, let us change its 
direction a trifle so that its central line will point toward the 
center of the Mediterranean Sea. First it lies over Mesopo- 


tamia. There in the highly fruitful plain we find the two great 
empires of Babylonia and Assyria. They were like their modern 
successors in the Europe of our own day. When they were weak, 
they were invaded by the more backward people from the moun- 
tains on the north and east or from the desert on the south and 
west. When they were strong, they waxed ambitious ; they strove 
to extend their borders ; they desired to rule the world ; and 
they were jealous of rival nations. Thus, at their strongest, like 
the great European nations which were locked in a death 
struggle only a few years ago, they fought tooth and nail for 
supremacy. The fighting in itself is a proof of superabundant 
energy. A weak people may fight in self-defense, or to gain new 
lands when sorely pinched with want at home, but only a people 
who have a surplus of both strength and wealth can stand the 
strain of great wars whose purpose is primarily national ag- 

On the flanks of our band of culture, as we call it, lay the 
Hittites on the borders of Mesopotamia and Anatolia. Beyond 
the Syrian desert the Phoenicians, Syrians, and Jews lived in 
the center of the band. Their degree of culture was equal to 
that of the Mesopotamians, but displayed itself in different 
ways, partly because of the accidents of mountain chains and 
seas, and partly because of peculiar circumstances of their 
racial character or history. Next comes Egypt, still within the 
belt. Here still another fertile plain gave opportunity for the 
accumulation of great wealth and for the leisure which is essen- 
tial to a part of the population if new ideas are to be developed. 
They fought the same kind of wars as did their neighbors on 
the east. When they were most powerful, their strength and 
energy were such that the mere conquest of their immediate sur- 
roundings did not satisfy them. Taking Palestine, they pene- 
trated Syria and even advanced to the Euphrates to fight with 
Assyria, their great rival. And the Assyrians in turn came down 
through Palestine to wrest the sovereignty from Egypt. 


Now we pass on, curving our band a little more, so that its 
center shall pass along the main axis of the Mediterranean Sea. 
Rhodes, the JEgean Sea, Greece, Italy, and Carthage fall within 
its limits. Here, too, we see the same phenomena of the rise and 
fall of great nations. The rise did not begin quite so early in 
the west as in the east, and the fall did not come so soon. In 
Greece, as in Mesopotamia, a growth in strength brought with 
it a great struggle for supremacy, which did not end till Athens 
had subdued her rivals. The wars of Rome and Carthage were 
of this same kind in which great nations, jealous of the great- 
ness of a rival, well-nigh destroy themselves. 

In this rapid sketch we have mentioned each of the chief 
civilizations of Asia and Europe up to the time of Christ. All 
were in their day centers comparable to those which we have 
seen to exist at present. One main center lay in China, and cor- 
responded to that of modern Japan. A second, less important 
and less enduring, was located in northern India. It has no mod- 
ern representative, unless we hold that the vogue of an esoteric 
Hinduism among a few people in America and Europe is a sign 
of the existence of a widely pervasive influence derived from 
an Indian center. The third center extended widely. Its eastern 
limit was on the western border of Persia. It embraced Meso- 
potamia, Syria, Egypt, and Greece, and on its flanks included 
surrounding countries such as Asia Minor. Ultimately it moved 
westward, so that Mesopotamia and then Egypt ceased to belong 
to it, while Italy was included. Finally, it migrated still farther 
westward and also northward until now Italy is on its south- 
eastern border, and its main area is the great European center 
of our own time. 

In the western hemisphere only two centers of civilization seem 
to have existed in ancient times. One was in Peru. We shall not 
consider it here, partly because it will come up in another con- 
nection, and partly because it failed to rise to a great height, 
and never succeeded in spreading its ideas very widely. The other 

Figure 48. The Shifting of the Storm Belt 

1 Regions of Great Storminess (Over 20 Centers per Year According: to Kullmer's Scale). 

2 Regions of Moderate Storminess (10-20 Centers). 
8. Regions of Slight Storminess (1-10 Centers). 

4. Regions Without Cyclonic Storms. . 

The Median Lines of the Main Storm Area and its Branches are Indicated by Heavy Solid Linen. 
The Hypothetical Median Lines of the Ancient Storm Belts are Shown by Dotted Lines. 


ancient American civilization, that of the Mayas, is much more 
important. It falls into the same class with those of Eurasia. 
Its fertility in ideas has already been discussed. Its influence 
spread to other lands, and may be seen in various ruins in 
Mexico, and in the calendars which were employed by several 
races in that country. It must have lasted many centuries, for 
we find splendid buildings whose dates are at least seven hundred 
years apart and possibly more. Moreover, before the first of 
these was constructed there must have been a long period of 
development during which the arts of architecture and sculpture 
were perfected. At that same period the Mayas must have been 
so far advanced that they kept most accurate records of astro- 
nomical phenomena, for otherwise they could not have deter- 
mined the length of the year with the extraordinary accuracy 
displayed in their calendar. In all these respects the Maya center 
resembled those of Eurasia. It differed from most of them in not 
leaving a successor. 

So much for the ancient distribution of civilization. Now for 
that of climatic energy. Storms, as we have seen are the most 
variable of the climatic elements and also one of the most im- 
portant in their effect on human energy. Figure 48 shows the 
approximate distribution of storminess in the northern hemi- 
sphere at the present time. It is constructed with the north pole 
in the center to show the complete storm belt encircling the north 
temperate zone. The lands arc shaded to represent three grades 
of storminess. Heavy lines indicate the centers of the main storm 
belt and its branches. The region of maximum storminess lies in 
southern Canada north of Lake Ontario. Thence the main belt 
extends eastward along the St. Lawrence River to the southern 
edge of Newfoundland, where it is joined by a branch coining up 
the Atlantic coast. Then it crosses the Atlantic with a slight 
inclination toward the north, and before reaching Ireland splits 
into three branches. One passes along the northern edge of Scot- 
land, through northern Scandinavia and thence along the Arctic 


coast of Europe toward Asia where it almost dies out and 
probably merges with the second or main branch. The latter 
splits into two parts which unite again. One passes through 
Scotland and southern Scandinavia. The other goes through 
southern England, follows the Baltic Sea and then, after join- 
ing its companion, extends eastward in the latitude of Moscow 
for an indefinite distance into Siberia. It apparently passes 
entirely across Asia, but in an attenuated form. The third 
branch swings from the central Atlantic toward the Bay of 
Biscay. It becomes weakened over southern France, strengthens 
once more in the stormy Gulf of Lions, continues with great in- 
tensity in northern Italy, then loses intensity as it crosses the 
Bosnian highland, and finally passes through southern Russia 
where it rapidly dies out. Returning to the main belt of stormi- 
ness we find that after it has crossed Asia it is joined in the 
Pacific Ocean by a branch which has been highly developed in 
Japan, but which weakens northward. The combined branches 
cross the Pacific Ocean to the American shore. Then in southern 
Canada and the northern United States, after crossing to the 
east side of the Rocky Mountains, the belt once more becomes 
extremely stormy. It is joined by a branch from Colorado and 
so completes its course back to the point of greatest intensity. 

Several features of Figure 48 deserve careful attention. In 
the first place, wherever the storms in their eastward course 
approach an extensive highland they tend to be weakened or 
deflected, after which they may or may not recover their former 
intensity. This may be seen on the western side of North Amer- 
ica where storms are relatively rare until the Rocky Mountains 
have been crossed. The highlands of western Europe are not great 
enough to destroy the storms, but the main belt is broken into 
several branches, each of which seeks to avoid the high country. 
The northern branch would apparently skirt the whole of 
Scandinavia were it not that some unknown force prevents it 
from going much to the north of the Arctic circle. The next 


avoids the Welsh and English highlands, crosses into the North 
Sea over the lowest part of England, receives an accession of 
intensity, and follows the line of least resistance along the Baltic 
and across the plains of Russia. Ultimately, however, the vast 
expanse of Eurasia, especially when it becomes a high pressure 
center in winter, largely overcomes the tendency of the air to 
move in the cyclonic fashion, and storms become rare. The third 
branch, which swings still farther south, is also greatly weak- 
ened when it reaches the land of southern France, but becomes 
very pronounced in the northern Mediterranean, only to be 
weakened once more by the Balkan highland. 

Another important feature of Figure 48 is the peculiar de- 
tached areas of high storminess in northern Italy and Japan. 
In the United States two similar areas are visible on a large 
scale map of storms, although they are masked in Figure 48. 
In both cases they are apparently remnants of a southern, or 
subtropical belt whose existence at times of many sunspots is 
described in Climatic Changes. Another belt where storminess 
increases greatly at times of sunspot maxima is found on the 
north side of the present belt. It tends to reduce the habitability 
of the northern parts of Europe and North America, but with 
that we are not now concerned. In the southern belt of increased 
storminess, when sunspots are numerous, the American areas 
move somewhat southward, become intensified, and lengthen 
east and west until they coalesce, forming a continuous, although 
very faint, belt. In Eurasia the same thing seems to happen, 
although the meteorological records in Asia are not yet suffi- 
cient to permit us to test it. If the American subtropical belt 
were intensified in the way that appears to have occurred in the 
past, its place of maximum storminess would probably be in 
the Gulf of Mexico. There the obstacles presented by the high- 
lands of the southwestern United States and Mexico give place 
to the open sea and allow free play for the development of 
storms. A development of this subtropical storm belt seems to 


be a pronounced feature of the changes which now take place 
from sunspot minima to maxima, and would presumably be 
magnified if the changes were on a greater scale than those of 
the 11-year cycle. Hence, we should infer that when the Mayas 
made their greatest progress, their country was blessed with 
a stormy area like that of the Gulf of Lions which now does 
much to make northern Italy far more progressive than the 
southern part of the country. Under such conditions the climate 
of Yucatan would have been comparatively stimulating in spite 
of its warmth, for during much of the year cool waves from 
the north would have been frequent. 

In Eurasia the same principles apply with appropriate modi- 
fications because of the topography and size of the continents. 
If the subtropical storm belt should be magnified in the way 
that seems characteristic of times of many sunspots, it would 
apparently reach its chief development in the places where the 
great civilizations of the past were located. The present Italian 
center would presumably move south and then expand eastward 
along the open Mediterranean. Leaving the highlands of Asia 
Minor on its northern flank, it would pass over the Syrian moun- 
tains because it could not spread eastward in any other way. 
Possibly it would be forced a little southward so that northern 
Egypt and Palestine would get its full force. In the lee of the 
mountains the storminess of the Syrian desert would be less 
than that of Syria, but by the time the storms reached Mesopo- 
tamia they would have had an opportunity to form themselves 
anew, and we should expect a well-developed center. In Persia, 
judging by what happens today, this would be weakened but 
not destroyed. Then the great plains of northern India would 
permit the storms to gather once more in a center corresponding 
to the faint one of today. That would probably be the end of 
any distinct belt for a thousand miles, for the eastern Himalayas 
and the mountains of western China interpose so tremendous a 
barrier that we should not expect the Japanese center, even 


though it moved southward and westward, to coalesce with the 
Italian. The plains of central China, especially the Yangtse 
valley, would be the place where the present Japanese center 
would be most highly developed, provided it suffered changes 
corresponding to those indicated in the corresponding American 
area. Japan, on the other hand, would presumably be less stormy 
than now, for the storm tracks would be pushed southward and 

If these things actually occurred at the times indicated by 
our California curve, the countries which now stand highest in 
civilization would then have had a long, cold winter, ending in 
a very stormy spring and followed by a cool damp summer. The 
stimulating qualities of the climate would have been less than 
now, and the possibilities of agriculture, especially in such 
places as Germany, would have been much diminished. In the 
countries like Greece where civilization was then at its highest, 
on the contrary, the number of storms and the duration of the 
stormy period would have been decidedly greater than now. 
The rainfall also would have been greater so that agriculture 
would have been favored. More important than this, however, 
would have been the high degree of climatic stimulus because 
of frequent changes of temperature. To apply the matter con- 
cretely, lower Egypt has an average temperature of about 80 
during July, and Mesopotamia and northern India are even 
hotter. Three thousand years ago the heat was probably almost 
equally intense at certain periods, although somewhat less ex- 
treme on an average, and by no means so uniform. All the 
summers were probably hotter than was the summer of 1911 
in the northeastern United States. That summer, in some lo- 
calities, was the most severe for a century. Yet its effect on 
work was no worse than that of an ordinary winter. In Meso- 
potamia and Egypt, summers of that kind doubtless made 
people slow and inert. They were probably not so bad as the 
present summers, however, for although no appreciable quan- 


tity of rain may have fallen, a large number of storms must 
have passed over regions not far to the north. Such storms 
would stir the air and bring fresh breezes. Everyone knows that 
in hot weather a change in the wind even without rain is most 
refreshing. When the summer was over, the storm belt, according 
to our hypothesis, would migrate southward in its normal fash- 
ion, and soon Egypt and Mesopotamia would be swept by storm 
after storm. During the early fall and late spring conditions 
would be about as they are in the homes of our Connecticut 
factory operatives during cool summers such as 1912 or 1913. 
For the intervening five or six months the average temperature 
would range from about 55 to 65 F., there would be a con- 
stant succession of cool waves, and the conditions would be 
almost ideal for great physical activity. Thus, even though the 
summers were distinctly bad, the total debilitating effect would 
be little greater than that of summer and winter combined in 
Connecticut. In Greece and Italy, with their more favorable 
mean temperature, conditions would be still better than in Egypt 
or Mesopotamia. In the same way favorable conditions appear 
to have prevailed in each of the great countries of the past at 
the time when it made its most rapid progress. 

The two phases of our climatic hypothesis are now before 
us. In point of time, though not of presentation in this book, 
the first step was a study of the climate of the past. Ten years 
of work along this line had led to the hypothesis of pulsatory 
changes, and finally to the idea that the changes consist pri- 
marily of a shifting of the belt of storms. After this conclusion 
had been reached, a wholly independent investigation of the 
effect of present climatic conditions upon human activity led to 
two conclusions, neither of which was anticipated. One was 
that in the eastern United States the cold weather of winter is 
as bad for work as for health, while only the warmest summers 
cause any serious curtailment of work. The other was that 
storminess and variability from day to day are of great im- 


portance. On the basis of these two conclusions it at once be- 
comes evident that the stimulating effect of climates in the same 
latitude and having the same kind of seasonal changes may be 
very different. It also becomes clear that the distribution of 
civilization at the present time closely resembles that of climatic 
energy. From this the next step is naturally back to our previous 
conclusion that changes of climate in the past have consisted 
largely of variations in the location of the storm belt. If this is 
so, evidently the amount of climatic stimulus must have varied 
correspondingly. Thus we are led to the final conclusion that, 
not only at present, but also in the past, no nation has risen to 
the highest grade of civilization except in regions where the 
climatic stimulus is great. This statement sums up our entire 
hypothesis. It seems to be the inevitable result of the facts that 
are before us. Other factors, to be sure, are also highly im- 
portant. One of them is natural selection, a subject so much 
neglected in its bearing on human history, that I made it the 
theme of a book on The Character of Races, which might almost 
be considered the continuation of the present book. The de- 
velopment of human culture and its spread from land to land 
is, I believe, a third factor quite as important as either of the 
others. Yet, unless we have gone wholly astray, the surprising 
way in which independent lines of investigation dovetail into one 
another seems to indicate that a favorable climate is one of the 
essential conditions of high civilization. 


HAVING seen that the objections to climatic pulsations 
are largely based upon misapprehensions, let us now take 
up certain other objections to our hypothesis of the relation 
between civilization and climate. "How about the high civiliza- 
tions of the past in places outside the storm belt?" the objector 
may say. "Yucatan and Guatemala may possibly have been 
stormy, but surely not Peru, southern Arabia, Rhodesia, Ceylon, 
Java, and Indo-China. Yet in the past these have boasted a 
civilization much higher than now prevails there." 

The force of this objection must frankly be admitted. The 
ruins of Indo-Chino and northern Ceylon, and any other traces 
of high civilization located in tropical lowlands, with the excep- 
tion of Yucatan and Guatemala, appear to have little relation 
to our hypothesis. Nevertheless, they do not require a modifica- 
tion of it. More probably they represent the triumph of other 
factors over the climatic factor. They apparently indicate one or 
both of two things. First, they appear to represent a temporary 
wave of progress due to the incursion of higher cultures from 
more favored regions such as India or the neighboring highlands. 
If that is so, they possess no more significance for our climatic 
hypothesis than do the railroads and other innovations intro- 
duced by Europeans within the past few decades. In addition to 
this they probably indicate that prolonged migration or other 
difficult circumstances gave rise to pronounced natural selection. 
Thus the people who built the wonderful ruins of Java and Indo- 
China, as I have shown in The Character of Races, and perhaps 


those of Ceylon, Peru, southern Arabia, and Rhodesia, had pre- 
sumably been gradually sifted so that only a very competent 
remnant was left. Under such circumstances the effects of cli- 
mate seem to be overcome for a while, but reassert themselves in 
due time as the strong inheritance becomes diluted or weakened. 

Another possibility is that the small and insignificant belt of 
storms which now traverses northern India may have been in- 
tensified in the past. In eastern India because of the barrier of 
great mountains, a branch may have swung southeast around 
the lofty Burmese mountains to the neck of the Malay Peninsula 
and then northeast to join the storm belt which now traverses 
Japan. In crossing the plains of Cambodia, where the most re- 
markable ruins of southeastern Asia are located, it may have 
developed a distinct storm center like that of northern Italy. 
The conditions would resemble those inferred in Yucatan and 
Guatemala, although perhaps less favorable because cold waves 
would be checked by the great mountains. Indo-China and Cen- 
tral America lie in the same relative position in .their respective 
continents, a fact which may have considerable significance. I do 
not, however, attach much importance to what has just been said 
about storms in southeastern Asia, for it is pure supposition. 
Other conditions, such as racial selection and the spread of the 
highly developed culture of India seem competent to explain a 
large part of the sudden rise of these regions, while the tropical 
climate largely explains their rapid decline. 

Yemen, Rhodesia, and Peru furnish admirable examples of 
comparatively high civilizations which developed in tropical 
highlands and lasted for a considerable period without much 
intercourse with regions of higher culture. They lie at such an 
altitude that the mean temperature never departs far from the 
optimum. For instance, at Fontein, near the Rhodesian ruins of 
Zimbabwe, the figures are 54 F. in June and 71 in November. 
For Yemen none are available, but judging by the altitude its 
temperature is probably slightly lower than that of Rhodesia. 


Even at Cuzco the elevated capital of old Peru, although the 
monthly mean temperature according to Hann ranges from 46 
in July to 52 in November, the conditions are very stimulating 
compared with tropical lowlands. The temperature is too low 
for comfort, to be sure, but it is of the type that appears to 
stimulate mental activity. If immigrants possessed of an un- 
usually high inheritance, either by reason of strenuous natural 
selection or of actual biological mutations, should come to such 
a region, the relatively stimulating quality of the climate would 
combine with their innate ability to enable them speedily to 
dominate the indigenous population, and to develop many new 
ideas. Yet we should not expect such a civilization to endure so 
long or rise so high as those in more favored regions. The people 
would tend to exhaust themselves for they would never experi- 
ence any restful changes of seasons, and would be stimulated at 
all times. To revert to an earlier illustration, their condition 
would be like that of a horse which is always driven at full speed. 
Such a horse might go rapidly for a while, but would wear him- 
self out at an age when carefully driven animals were in their 
prime. The constant nervous excitation produced by such a 
climate in immigrants from a less favorable region would induce 
both progress and decay. The most nervous people would die 
out partly because they would exert themselves too strenuously, 
and partly because nervousness is a potent agency in reducing 
the birthrate. Self-control would also be weakened, thus leading 
to vice and excesses of various kinds. The chewing of the coca 
leaf, a narcotic stimulant which is thought by many people to 
be one great cause of the backwardness of Peru today, would 
harm the high-strung, competent parts of the community more 
than the dull, apathetic ones. In various other ways such a 
climate as that of Peru would be stimulating for a while, but 
would lead to exhaustion sooner than would one where greater 
variability prevails. 

We now come to perhaps the strongest objection aside from 


the question of the reality of climatic changes. A large part of 
this book has been concerned with the United States. The present 
status of that country is one of the main foundations which 
originally led to the framing of our hypothesis. Yet before the 
coming of the white man savagery prevailed where civilization 
is now highest. In the sixteenth century the climate must have 
been approximately the same as that of today, so that no expla- 
nation can be sought along that line. It is true, to be sure, that 
before the coming of the white man the most energetic and 
capable of the Indian tribes lived in what is now the north- 
eastern United States. Dixon, for example, in The Racial His- 
tory of Man, says that the "Iroquois and southern Algonkian 
tribes were among the first of those north of Mexico in ability 
and prowess." Many other authorities speak in similar fashion. 
Wissler in Man and Culture reproduces a map by Moorhead 
showing that the region from Illinois to New York was an im- 
portant center of culture from which many new types of stone 
ornaments spread in all directions. 

In spite of this we are still confronted by the stubborn fact 
that before the coming of the white man no great civilization 
had ever developed in the northern United States, while Mexico, 
although far inferior climatically, harbored a relatively civi- 
lized population. At first this seems to prove that our hypothesis 
cannot be correct. Yet more careful examination leads to a dif- 
ferent conclusion. The distribution of civilization in pre-Colum- 
bian America merely brings out a fact which I have again and 
again tried to emphasize : although climate is highly important, 
there are other factors whose weight is equally great. Even if 
our hypothesis be fully accepted, no less importance will thereby 
attach to the other great factors which condition the events of 
history. Because a man dies for lack of air, we do not think that 
air is more essential than food, drink, warmth, the circulation of 
the blood, the reproduction of the species, the ravages of viru- 
lent germs, and many other conditions. So it is in history. Even 


if our climatic ideas arc correct, it will still be true that the 
ordinary events of the historical record are due to the differing 
traits of races, the force of economic pressure, the ambition of 
kings, the intrigues of statesmen, the zeal of religion, the 
jealousy of races, the rise of men of genius, the evolution of new 
political or social institutions, and other similar circumstances. 
Yet a comprehension of the part played by the climatic factor 
will enable us to explain some of the many events which hitherto 
have puzzled us. Not all will be thus explained, for others must 
wait until the action of some other set of as yet unknown condi- 
tions is understood. 

In the present case I believe that the explanation of the fail- 
ure of the Indians to rise to a level equal to that of the people 
of the Old World is found partly in inheritance, and partly in 
the history of their culture. I shall not dwell on inheritance, 
although it may be of great importance. In The Red Man's 
Continent and more fully in The Character of Races I have set 
forth the hypothesis that the aboriginal Americans during their 
migration from Asia by way of Siberia and Alaska suffered an 
adverse natural selection due to the severe arctic environment. 
This may have given them a permanent handicap compared with 
the people of Europe and western Asia among whom the selec- 
tion was peculiarly favorable. Among the Americans, so it seems, 
there was a premium on powers of passive resistance and en- 
durance. Moreover, among all hunting tribes there is a premium 
upon the ability to make sudden but not prolonged efforts such 
as are involved in hunting and raiding. Only when agriculture is 
introduced does a new type of natural selection put a premium 
upon such qualities as steady industry. Among hunting tribes, 
moreover, the acquisitive temperament which stores up food or 
other property for periods of want, is not nearly so great an 
advantage and hence so strong a selective factor as among those 
who practice agriculture. Because the wandering hunter cannot 
transport much property. J^ loses the biological advantage 


which causes the people who have a careful, thrifty spirit to have 
a greater chance of survival than have the careless and un- 

Turning now to the cultural side of early America, at least 
two great factors appear to have imposed a tremendous handi- 
cap upon the Indians of the northeastern United States. One is 
the absence of tools of iron, and the other the lack of beasts of 
burden. These, in conjunction with the type of vegetation, offer 
such hindrance that the Indians could probably never have 
developed a very high civilization, even if they had been as com- 
petent as the races of Europe. The discovery of the use of iron 
depends on the coincidence of three conditions whose occurrence 
is almost accidental. One is the birth of a man with sufficient 
inventive genius to devise a way of obtaining the metal from 
rocky ores. The second is the occurrence of ores and other neces- 
sary materials within easy reach of such a man. The third is 
that the genius must be so relieved from the fear of enemies, the 
danger of starvation, and the ravages of disease that he has both 
time and strength to elaborate his idea. The combination of 
these three fortunate circumstances never occurred in America. 
Although a little native copper was used, we have no assurance 
that the ore was ever smelted in any large amounts. It certainly 
never was used to any great extent. Iron, except a few bits from 
meteorites, was absolutely unknown. Hence, through no fault of 
their own, the original Americans were dependent upon such 
tools as they could fashion from flint, obsidian, and other stones, 
or from bones, shells, wood, and similar materials. 

We are so accustomed to iron tools that we scarcely realize 
their immense importance. Consider their effect upon agricul- 
ture. Go into a virgin forest with its labyrinth of trees. Imagine 
the task of cutting them down with a stone hatchet. The mere 
physical labor is such that none but people of high energy 
would ever attempt it. An easier way is to girdle the trees, 
cutting off the bark in a circle, and then leaving them to dry 


until they can be burned. Even that, however, is a long process. 
In the moister parts of the world its difficulty is greatly in- 
creased by the fact that while the trees are becoming dry enough 
to burn, new vegetation is rapidly growing. In many tropical 
regions, as we have already seen, the clearing of the forests is 
scarcely feasible even today. In temperate forests the difficulties 
are not so great, but they are practically insurmountable from 
the standpoint of a savage who has never known the meaning 
of hard, steady work. In the hunting stag a man may follow 
the trail until he falls from exhaustion, but that does not give 
him the power to wield a stone axe day after day upon stubborn 
trees. Hence, if agriculture is to be practiced by primitive people, 
it must originate in regions where there are no forests. The 
vegetation must be such that the primitive savage with his hands 
or with a stick or stone can easily grub it up. Or else it must be 
so scanty that it will not interfere with his crops. Anyone who 
has seen the agriculture practiced by people who are just emerg- 
ing from some other mode of making a living knows that the 
fields are sown in the spring and then generally left untended 
until the time of harvest. Since the people are not yet able to 
get their living entirely from the crops, which is always the case 
during the transition period, they must perforce carry on the 
old occupations while the crops are growing. Hence, the weeds 
are allowed to grow as freely as the grain. In a dry climate where 
the natural growth consists only of bunchy grasses or low bushy 
weeds which grow apart from one another and can easily be 
pulled up with the hands before the next sowing, this does little 
harm. In wetter regions, such as the forested areas, the weeds 
arc much more difficult to eradicate. 

The reader has probably noticed that I have said nothing 
about grass-lands. The reason is that primitive people never 
attempt to cultivate them. If grass covers the entire ground and 
forms what we commonly call sod, crops cannot be raised in it. 
The dry grass may be burned off in the early spring, and seeds 


may be dropped in holes punched with a sharp stick, but no crop 
will be reaped. The roots of the grass are not killed. The new 
blades shoot up at once, and by the time the seeds begin to sprout 
are so high as to strangle them. The primitive savage who has 
no iron tools cannot possibly dig up the sod. Even if he has such 
tools, the laboriousness of the task bans it as a practical method 
of making a living. If anyone doubts this, let him spade up a 
turfy spot ten feet in diameter. Then let him calculate how many 
days he would have to dig in order to make a living for himself 
and his family by sowing grain. Let him also determine how a 
primitive savage who had to do this task would support himself 
and his children while he was digging before he could get a first 
crop. Finally, remember that the savage had no good spade to 
help him, but only a clumsy, heavy stone set in a handle, a 
brittle bone, or a piece of wood rudely shaped into a flat imple- 

I have emphasized the difficulties of grass-land because they 
apply directly to the problem of civilization among the Indians. 
The part of North America which is highly stimulating cli- 
matically is covered either with grass of the prairie and great 
plains type, or with temperate forest. It is universally recog- 
nized that a high state of civilization is impossible unless it is 
based on agriculture. Otherwise people must wander all the 
time. They cannot accumulate the appliances which are essen- 
tial even to the lowest real civilization. They are not attached 
to the soil, and thus have no incentive to improve a particular 
tract. If they possess domestic animals, the case is better, for 
these foster the sense of ownership and various other feelings 
which serve as uplifting influences. In North America no do- 
mestic animals except the dog and the turkey were known to the 
aborigines. This was not the f $ult of the Indians. The horse and 
camel families were then extinct in North America. The bison 
was the only animal of the ox family with which the Indians 
came in contact. It was too large and fierce to be domesticated. 


The mountain sheep might possibly have been tamed, but it is 
very wild, its habitat is the barren mountains, and it is too small 
to plough sod. Even if the Indians had been familiar with the 
idea of taming beasts of burden, they could not have achieved 
any important success. 

Without beasts of burden ploughing is impossible. Unless the 
ground is ploughed, grass-lands, as we have seen, cannot be 
cultivated. Therefore, civilization could not flourish in the 
grassy plains of North America before the coming of the white 
man. A few highly favored spots such as river flood plains 
where the grass grows in bunches and does not form turf were 
cultivated, but the areas of that kind were too small and scat- 
tered to give rise to any widespread progress. They were ex- 
posed to the ravages of Indians who had not yet learned the 
value of permanent abodes and individual property, two pri- 
mary requisites of civilization. The people who lived upon them 
were swamped in the flood of surrounding savagery. Moreover, 
the places which they were able to cultivate were subject to 
floods and other disasters, so that the cultivators were often 
forced to rely on the chase. Then again, without iron tools or 
beasts of burden, a man cannot cultivate a large area because 
the task is so great. Therefore, the crops were likely to be 
insufficient to support the family throughout the year even 
when the harvest was good. The only recourse was the chase. 
In Asia people who were in such circumstances might rely on 
domestic animals, but not in America. Hence, it was practically 
impossible for the Indians of the grassy plains to get away from 
the savage life of the hunter. 

In the forests which covered all the eastern states conditions 
were scarcely better. A man might girdle enough trees and cut 
enough brush to make a small field. When the wood was dry, 
he might burn it and obtain a crop of corn. While it was ma- 
turing he and his famity would make a living by hunting and 
fishing. The crop would support them through the winter, but 


it is extremely doubtful whether they would ever cease to regard 
hunting as a main source of livelihood. The reason is this. The 
first crop on a burned piece of forest land in the eastern United 
States meets with little difficult} 7 . For the second crop it is 
necessary to cut down and burn the weeds and bushes that have 
grown up during the preceding summer. Remember that the 
savage has no iron hoe, his seeds are planted haphazard here 
and there among the stumps, and he cannot tend his garden 
while it is growing, but must go off and hunt. When he cuts 
the bushes and weeds the second spring he does not root up the 
grass. He has no spade with which to dig it up, and no ox or 
donkey to draw a plough. If he takes good care of his field he 
soon finds that he has a meadow of tough sod on his hands. If 
he neglects it, he has a few acres of bushes. In either case if 
he would make a living from agriculture, he must go through 
the labor of clearing a new field. Meanwhile he still must be a 
nomadic hunter. He takes no great pride in his field ; he does not 
care to improve it ; he rarely builds a permanent house beside 
it. Why should he? Next year, or at most in two or three years, 
lie must build another. In a few specially favored spots the con- 
ditions may be such that agriculture is not quite so difficult. In 
the North, where the stimulating climate is found, such spots 
are few and small. The chief reason for wonder is that the 
Indians had energy to cultivate any crops whatever. In the 
southern states the grass does not form so dense a sod as in 
the North, but even there the difficulties are great. Yet a begin- 
ning had been made, and the civilized nations, including the 
Cherokees and others, lived in permanent villages and practiced 
agriculture as their main means of getting a living. If they had 
had iron tools and oxen, America today might be filled with 
highly civilized Indians instead of Anglo-Saxons and other 
Europeans. Thus, although an appropriate physical environ- 
ment and a strong mental inheritance may be essential to the 
rise of a great civilization, these two conditions may be at their 


best, and yet savagery may prevail because certain cultural 
essentials such as iron or beasts of burden are lacking. 

From this example of people who lived in one of the finest 
climates but failed to make progress, let us turn to a case of 
quite the opposite type. The white settlers in northern Aus- 
tralia live in an almost tropical climate, which is poor as climates 
are rated in this book. Nevertheless, they maintain a high civi- 
lization and believe that they can raise that civilization still 
higher. They are sometimes cited as proof that climate in itself 
has little or no effect on health and that high civilizations may 
arise regardless of climate. Nowhere else in all the world does so 
large a body of white people, chiefly of British descent, live 
within the tropics. Some two hundred thousand upon whom the 
sun shines vertically at certain seasons are doing all the work 
of life with their own hands. The men work in the fields, on the 
docks, and among the cattle and sheep ; they cut sugar cane 
under the tropical sun ; but their health docs not appear to 
suffer. The women work in intolerably hot kitchens, often among 
swarms of pestiferous flies, and in rooms where the blazing sun 
on the unceiled roof joins with the kitchen fire to produce an 
appalling temperature. Yet their death rate is phenomenally 
low, and they give birth to unusually healthy children. In fact 
the death rate in tropical Australia among all classes of the 
population is one of the lowest in the world. 

In order to make fair comparisons between regions where the 
proportion of young people is unusually large and those where 
the proportion is smaller, let us use what is known as a "standard 
population." On this basis, which is universally accepted as the 
fairest yet devised, the death rate in Queensland, the most 
northerly state of Australia was 12.1 during the normal years 
before the World War. Compare this with 10.5 in New Zealand 
which is the healthiest country in the world, 12.4 in Denmark the 
healthiest country in Europe, 15.2 in England, and 16.1 in the 
part of the United States then included in the registration area. 


In addition to this the medical examinations of young men who 
enlisted during the World War showed that the Queenslanders, 
even the tropical Queenslanders, were certainly not less robust 
and vigorous than those from other parts of Australia and much 
more so than were the similar men from England. Moreover, 
children of the second and third generation have been born in 
tropical Australia and are fine, active specimens. It seems to be 
proved beyond question that the white man can live in tropical 
Australia, that he can enjoy good health, and that white children 
of high vitality can be born there, live there all their lives, and 
become the parents of other children who seem to be equally 

These facts are highly important and encouraging. They hold 
out a definite and not unreasonable hope that some day a branch 
of the white race may live permanently within the tropics and 
carry on all the work of life without the help of any colored race. 
The fond hope of the Australians that there may permanently 
be a "White Australia" is by no means without foundation. Does 
this invalidate our hypothesis of the relation between climate 
and civilization? Let us see what the facts really are. The Aus- 
tralians are so much interested in the problem of a White Aus- 
tralia that their Commonwealth Statistician has issued a special 
bulletin on tropical Australia. He has also kindly placed at 
my disposal certain other unpublished data. I am afraid that I 
shall seem to the Australians to use these data in a wa}^ that they 
will not like. But after all, what they really want is the truth. I 
am perhaps as keen as they for a White Australia ; not only do I 
want to see my own race show its ability to conquer every kind of 
environment, but I am extremely anxious to see a conclusive 
tropical experiment on a large scale. I want to know beyond ques- 
tion whether white men can live permanently in a tropical coun- 
try, conquer the diseases, and make progress without the help or 
hindrance of any colored race. Tropical Australia affords by 
far the greatest opportunity for such an experiment. It is 


peculiarly free from tropical diseases, and there seems to be no 
good reason why it should fail to be kept free ; its colored in- 
habitants are few in number and most of them belong to the 
aboriginal Australian race which seems to be dying out and 
which is quite easily kept separate from the whites ; and it is 
under a government which is disposed to do everything possible 
to make the experiment a success. I would give a great deal to be 
able to see what kind of people live in tropical Australia one or 
two hundred years hence. But if the tropical Australians of the 
next few generations are to succeed indeed, if they are to avoid 
great misery perhaps they must know exactly what they are 
facing. To let the dream of a White Australia and the hope of 
developing a great country blind ourselves to the facts is sure 
to produce evil. 

We have already seen how extraordinarily low is the death 
rate of Queensland. If we take only the part of Australia that 
lies within the tropics we find that during the years 1920, 1921, 
and 1922 the following remarkable conditions prevailed. 





as a 






Birth rate per 1000 women aged 15-44 




Infant death rate per 1000 births 




Female death rate per 1000 




Male death rate per 1000 persons 




In the first three of these conditions non-tropical Queensland 
is more healthful and vigorous than Australia as a whole, while 
tropical Queensland is still more healthful and vigorous. In 
other words the white women in the tropical part of Queensland 
enjoy remarkably good health; they give birth to a relatively 
large number of children ; and those children are uncommonly 
healthy. What more could one ask as a recommendation of the 
climate of a country ? The men, to be sure, have a much higher 


death rate than those of other parts of Australia, but from the 
standpoint of the future of the race they are much less im- 
portant than the women and children. The Census Bulletin on 
Tropical Australia attempts to explain the differences between 
the death rates of men and women as follows: "As both sexes 
should be affected by tropical conditions to something approach- 
ing an equal degree, it is apparent that there must be some cause, 
apart from purely tropical attributes, to account for the un- 
favorable male death rate. . . . The great excess of men over 
women in the tropical population suggests that there are many 
men living under primitive conditions. Under such circumstances 
there is too frequently a disregard for precautionary sanitary 
measures, and a reckless neglect of the first symptoms of disease. 
There are other cases, too, where it is impossible by reason of 
great distance to procure medical or surgical assistance. It 
would appear to be mainly to such circumstances as these that 
the high male death rate in the tropical parts of Queensland is 
due. Otherwise, the great difference between the mortality of the 
sexes is not readily explained." 

There may be some truth in this, for in tropical Queensland 
there were in 1921 about 133 men for every 100 women. Never- 
theless it must be a minor factor. Not only is it generally be- 
lieved that frontier life is far more healthful than city life, but 
much more than half the men of tropical Australia, as well as 
a still larger proportion of the women, live in the towns where 
there are physicians and often hospitals. Moreover, as appears 
in the last sentence of the quotation from the census bulletin, 
the isolation of the *nen on the frontier is appealed to as an 
explanation of their high death rate only in the absence of any 
other reasonable cause. 

There is, however, another reasonable cause of the low death 
rate among the women, a cause which the Census recognizes as 
applying to the population as a whole, but does not recognize as 
applying to women more than to men. That cause is natural 


selection. As the bulletin on tropical Australia puts it : "Per- 
haps the most potent influence [in causing the low death rate of 
tropical Australia] has been that sort of natural selection which 
operates in the settlement of all new territories. It may be stated, 
as a rule, that only the bolder and more virile of any community 
will venture on the role of pioneer in new unsettled country, and, 
when such a new country is a tropical one, to which popular 
opinion generally ascribes more than the usual discomfort, the 
physical standard of the settlers is probably more than ordi- 
narily high." 

The logical corollary of this statement is that among women 
the selection of those who are physically fit is much stronger 
than among men. Young men rarely think of their health ; young 
women think of theirs a great deal, and between men and women 
30 to 50 years of age the contrast is still greater. That the 
women distribute themselves over tropical Australia in a dif- 
ferent way from the men is obvious from the fact that in the 
tropical part of western Australia, which is the most inacces- 
sible and undeveloped, there were in 1921 about 524 men for 
every hundred women ; in the tropical part of the Northern 
Territory, which is not quite so remote, the number of men per 
hundred women was 271 ; in tropical Queensland, which is still 
better, 133 ; and in Towns ville, one of the two largest cities, 108. 
On the other hand, in Rockhampton, which is the largest city 
of tropical Australia and also the one located farthest south 
and hence in the least enervating climate so far as the coast is 
concerned, the number of men per 100 women was only 94. In 
other words the women become relatively more and more numer- 
ous as one gets away from two conditions, namely the frontier 
and a truly tropical climate. 

But this does not end the matter. The women tend not only to 
concentrate in the best parts of tropical Queensland, but to 
remain out of tropical Australia altogether, or else to go away 
after once getting there. This is evident from the fact that 


among children up to the age of about fifteen years the relative 
numbers of boys and girls are normal. From that age onward 
the number of men in proportion to women steadily increases. 
For example, among young people 15 to 19 years of age there 
are 110 boys for 100 girls, but at the age of 30 to 34* years this 
proportion has increased to 155, while between the ages of 65 to 
69 it rises to 24*9. Yet in a normal population at this latter age 
there are only about 89 men for 100 women. Where such con- 
ditions prevail it needs no demonstration to prove that the 
women either have never come to tropical Australia or have 
come and gone away. In either case it is certain that a large 
number of the women are missing because of their health. One 
has only to talk with those who are still there, or with the 
Australian physicians, to learn how often the men like the cli- 
mate while the women dislike it, and how often the health of a 
wife or daughter causes a family either to move away, or to be 
temporarily separated. The women frequently go to the cooler 
South, while the men stay in the tropical North. Often the whole 
family moves away from tropical Australia because the women 
do not like the climate. The selective process which causes the 
men in a new tropical country to be especially strong and vigor- 
ous works still more effectively in causing the women and hence 
the children to be even more markedly of the same type. The low 
death rate in tropical Australia does not indicate that the 
climate is favorable, but merely that natural selection has been 
unusually vigorous. 

Now look at the matter in still another way. Here is a little 
table showing the death rate among persons from 15 to 49 years 
of age in the three Australian states of Victoria, which is the 
most southerly and hence the coolest, New South Wales which 
also lies quite far to the south, and Queensland which lies so far 
to the north that a quarter of its population is within the 
tropics. The death rate has been calculated according to a 
"standard population" so as to eliminate any differences arising 


from the fact that there are more young people in one section 
than in another. The residents of the three states have been 
divided according to their birthplace, the great majority of 
Australians being natives of one of the three states, or else of 
England or Scotland. 




1920, 1921, 1922. 


Male Female 

South Wales 

Male Female 

Male Female 

M. F. 


New S. Wales 



















Grand average for 

the two sexes 4.39 3.75 4.35 

The significant fact about the table is this : no matter whether 
they reside in Victoria, New South Wales, or Queensland, the 
people who were born in Queensland have a higher death rate 
than those born in the other two Australian states or in Eng- 
land or Scotland. If we combine the figures in the last column 
it appears that the residents of Australia who were born in 
Victoria, England, Scotland, and New South Wales have an 
average death rate of 4.01. On the other hand the death rate 
among the people born in Queensland, no matter where they 
reside, is 4.66 or approximately 15 per cent greater. The high 
death rate of Queenslanders in Victoria, or New South Wales, 



may be due to the fact that Queenslanders whose health is im- 
paired migrate to those cooler states. But in that case the born 
Queenslanders who remain in Queensland ought to be stronger 
than the average and their death rate should be correspondingly 
low. On the contrary, their death rate exceeds that of the people 
born in any of the other four regions. In other words, although 
the people whose residence is in Queensland have a very low 
death rate, those who were born there have a high death rate. 
Those who reside there were largely born elsewhere, and have 
had the advantage of a strenuous though unconscious process of 
natural selection. Those who were born there are more nearly 
like the average of their race than were their selected parents, 
for that is the universal biological rule, and they show what 
seems to be the effect of the tropical climate. 

Another significant fact in this connection is the number of 
children per family. We have already seen that in proportion 
to the number of women between 15 and 44 years of age the 
birth rate in Queensland is high compared with the rest of Aus- 
tralia, and is still higher in the tropical sections. That appar- 
ently is due to the fact that the weaker women either leave their 
husbands in the North arid go to the cooler South, or else per- 
suade their husbands to move away. Those who remain are 
strong and vigorous and have many children. But when we 
examine the number of children born to persons who are Queens- 
landers by birth, regardless of what part of Australia they later 
reside in, we find quite a different condition. The following 
figures show the number of children born to persons whose own 
birthplace was in various regions and who died in Australia 
during the year 1921. 

Germany 6.3 Tasmania 5.0 

Ireland 5.8 South Australia .... 4.5 

Scotland 5.7 Victoria 4.1 

England 5.4 Queensland 3.8 

New South Wales . ... 5.1 


The high birth rate among the foreign-born Australians is 
normal. There is nothing surprising about the differences among 
the birth rates of people born in New South Wales, Tasmania, 
and South Australia. The low rate among natives of Victoria, 
however, is not easily explained unless it be that Victoria, more 
than any of the other states, has lost the pioneer, frontier 
quality, and hence has the relatively low birth rate which is 
normal in old regions. For Queensland, no such explanation can 
be advanced, for that state has more of the pioneer quality than 
any other in our table. The most probable explanation is that 
the birth rate is low for the same reason that the death rate is 
high. Both conditions indicate that in spite of the strong selec- 
tive process to which their parents were subjected, the native- 
born whites of Queensland display qualities which suggest a 
lower degree of physical stamina than prevails among the other 
Australians, and which seem to be the result of the tropical 
climate. If this is the case it strongly bears out the general 
thesis of this book. 

Even the part of Australia where the tropical Queenslanders 
live is not tropical in the ordinary sense. The climate is indeed 
quite trving by reason of the length and monotony of the summer 
and because of the dampness near the coast and the great heat 
in the interior. There is, however, a real winter in the regions 
where most of the tropical Queenslanders actually live. For two 
or three months the temperature almost everywhere falls to 
between 40 and 50 during the night, while on the highlands 
there is often frost. If a climate so mildly tropical can produce 
such clear results, it seems probable that a thoroughly tropical 
climate may handicap the white man to a far greater extent. 
Nevertheless, I do not despair of the ultimate triumph of the 
white man over the tropics, and much less do I despair of a 
White Australia. The process of selection for climate has never 
been really tested. All that has happened thus far has been 
purely fortuitous. The hope of the future, I believe, lies in an 


orderly and far-sighted selection of the right types of people, as 
well as in the further development of tropical medicine and 

But suppose the matter of health should be taken care of to 
such a degree that the white race could live, thrive, and per- 
manently reproduce itself within the tropics, would civilization 
there advance as in cooler regions? I doubt it. In the first place 
the most casual observation in any tropical region shows that 
the white man as well as the colored does not act with so much 
energy as in cooler climates. No matter how good his health, he 
is forced to work comparatively slowly or for short hours, or 
else he exhausts himself. It was a Queensland sheep "selector," 
the owner of twenty or thirty thousand animals, who first called 
my attention to the "Queensland walk." We were watching a 
man who slowly sauntered from the hotel to the railroad station. 
"That's the way we all walk after we've been here in tropical 
Australia a while." Not only do people almost of necessity walk 
that way, but they often work that way. In tropical Australia, 
just as in other tropical countries, all sorts of things are allowed 
to lie at loose ends much more than among the same kind of 
people in more stimulating climates. 

The new point which I wish to make in regard to Australia 
is that natural selection works against a tropical country, and 
is working that way even more now than in the past. This sounds 
like a contradiction to what has just been said about the strong 
physique of the Queenslanders and the possibility of building 
up a genuine tropical race of white men. But there is no con- 
tradiction. I am talking now about the qualities which lead to 
progress in civilization. As one goes about in tropical countries 
and especially in Australia, one soon finds that the people who 
complain most about the climate are, first, the women, and then 
the professional men. In other words it is the people whose work 
keeps them indoors. The rancher, planter, promoter, real estate 
agent, cane cutter, and dock laborer do not seem to feel the heat 


half as much as do the minister, lawyer, doctor, engineer, and 
teacher. These intellectual workers may and do adapt them- 
selves to the climate and achieve results of high importance. 
Nevertheless, almost without exception, they are on the watch 
for a chance to get away to a pleasanter and more stimulating 
climate. Many of them are ready to accept smaller salaries for 
the sake of being in an atmosphere which is physically and 
mentally more stimulating. In this fact, perhaps, lies one of the 
greatest hindrances to the development of a high civilization 
in countries with unfavorable climates. We have already seen 
this selective process at work in the Bahamas, it is very active 
in tropical Australia, and it is energetically at work in the 
southern United States. The greater the wealth of a country, 
the greater its intellectual and physical activity, the better its 
transportation system and the more fully it picks out and edu- 
cates all its bright sons and daughters, the more likely those 
same sons and daughters are to move away from the unstimu- 
lating environments and into those which most fully give scope 
to all their faculties. In this respect, as in so many others, each 
new advance of knowledge, each new step in the mastery of 
nature, gives greater power to the regions whose climatic ad- 
vantages already help them to be leaders. To him that hath 
shall be given, and from him that hath not shall be taken away 
even that which he seemeth to have. 


WE come now to the final step in our study of the hy- 
pothesis that climate ranks with racial inheritance and 
cultural development as one of the three great factors in deter- 
mining the conditions of civilization. As to which of the three is 
most important it is impossible to say. The absence of good 
conditions in any one respect may hold a country back, while 
all three must rise to a high level if a race is to reach the highest 
plane of civilization. In this last chapter I propose to consider 
one final objection to the general hypothesis that climate has 
been a determining factor in the geographical distribution of 
human progress. That objection is that it seems impossible that 
changes of climate can have exerted so great an influence as is 
claimed in this book. 

The first and most obvious effects of climatic changes are 
economic. We have said little about them in this book because 
they have been fully discussed in the publications numbered 2, 
3, 7, 8, 10, 12, 14, 15, 17, and 22 in the list at the end of the 
preface. A single concrete case will illustrate the matter. In 
1909 I visited Palestine. That happened to be an unusually dry 
year. During the months of April and May I rode scores of 
miles on horseback amid fields of wheat that showed merely a 
few scanty stalks three to six inches high. In Beersheba I talked 
with a number of men who had tried to raise grain during a few 
preceding years of good rainfall, but were financially ruined 
by the drought of 1909. In Moab many villages which had been 
recently reoccupied under the stimulus of the building of the 


Mecca railroad were being abandoned. The inhabitants were 
moving back across the Jordan to the better watered parts of 
the country. Coincident with this migration of the agricultural 
people away from the drier areas along the borders of the desert, 
there was a corresponding outward movement of the Arabs from 
the desert. Because of the drought the great tribes from the 
interior of the Arabian desert swarmed over the grain fields 
on the eastern and southern border of Palestine, and let their 
camels eat up the few scattered stalks of wheat that had sur- 
vived. The poor villagers shot at the Arabs when they first 
appeared ; then ran in terror to the villages. Soldiers were sent 
to stop the Arabs, but in vain. The quarrels between the Arabs 
and the peasants resulted in so many gunshot wounds that Dr. 
Patterson of the Presbyterian Hospital at Hebron was swamped 
with patients. I myself was in an Arab encampment when it was 
raided by other Arabs. I was held up and my money demanded 
at another time, and I came in personal contact with raiding 
parties on three other occasions. Thus a single year of drought 
brought distress upon all kinds of people ; it caused migrations 
among those of the settled population who occupied the least 
favored locations ; it set the desert tribes in motion ; and it 
spread poverty, hunger, raids, war, wounds, and death on every 

Consider now what must have happened when Palestine 
changed from a condition of relatively abundant rainfall in the 
early part of the Christian era to a condition drier than that of 
today in the seventh century. Remember that at certain periods, 
such as the third century B.C. and the beginning of the seventh 
century A.D., a relatively rapid change took place. Remember 
ioo that Professor Butler of Princeton has been quoted above 
as saying that an area of "20,000 square miles of land on the 
(astern border of Syria is now too dry for permanent human 
occupation, but was once more thickly populated than any area 
of similar dimensions in England or in the United States outside 


the immediate vicinity of the large modern cities." This must 
mean a population of at least 100 per square mile or 2,000,000 
people. South of the region described by Butler there are addi- 
tional thousands of square miles of similar dry land full of 
ruins, while further east, in northern Mesopotamia, in the 
region described above by Clay, the same is true. Suppose for 
the sake of argument that 3,000,000 people lived in these areas 
which are now too dry to be occupied. 

When a diminution of rainfall gradually rendered this great 
multitude homeless, a corresponding reduction must have taken 
place in the productivity of the areas which are still inhabited. 
Palestine today contains about 650,000 people and Syria about 
3,000,000. There is abundant evidence that when the outlying 
districts were habitable the population of the still habitable 
areas was much greater than now. It seems, then, that at the 
time of Christ, or at least some 400 years earlier, there may 
have been over 6,000,000 people in these areas of Palestine and 
Syria. Then what happened? Regions which had been sup- 
porting perhaps 9,000,000 people in comparative comfort were 
so stricken by drought that the homes of about three million 
became almost uninhabitable, while the productivity of the 
remainder was reduced nearly half. Thus only about three and a 
half million people could live where 9,000,000 had lived before. 
Of course so great a decline did not occur in a single generation 
or even a single century. But a reduction of the capacity of the 
country from 9,000,000 to 8,000,000 persons would produce 
misery, famine, death, migration, raids, wars, and misgovern- 
rnent to an almost incredible degree. Then would follow a few 
decades or scores of years of recovery and again a reduction 
in the capacity of the country to support people. Each such 
blow must have dragged civilization downward, and the result- 
ant chaos of the Dark Ages is by no means surprising. 

The misery and discontent due to prolonged poor crops tend 
to make people unstable not only politically, but in other ways. 


Religious bitterness is almost sure to increase under such con- 
ditions. A portion of the community attributes its poverty to 
the fact that there is something wrong with the present form of 
religion. The rest are inclined to attribute their distress to the 
wickedness of their neighbors who decry the old religion. Thus 
bitterness and persecution are engendered. Those who become 
discontented with the old religion are prone to accept the new 
ideas propounded by religious enthusiasts. This seems to have 
been the case when Mohammed made his appeal to the Arabs 
after the prolonged period of increasing aridity which cul- 
minated with a sudden access of dryness in the first half of the 
seventh century. Without the genius of Mohammed that long 
period of adversity might have come to an end without any 
serious upsetting of the old conditions ; but without the dis- 
content and unrest fostered by years of distress Mohammed 
might have appealed in vain, for he would have had to speak to 
men who did not desire change, instead of to those who ardently 
longed for it. 

The people of the desert may perhaps occasionally pour forth 
from their homes without any special stimulation, but this is 
doubtful. Anyone who has had much to do with the Arabs and 
other desert nomads knows that when there is plenty of water and 
grass there is very little raiding and fighting. On the other hand, 
a single dry year causes raids in the fashion described above; 
and prolonged dry periods appear to lead to great outbursts 
of desert people like that which reached its crest under the influ- 
ence of Mohammedanism, although it began before Mohammed 
came into prominence. The Mohammedan migration was by no 
means unique. Many of the barbarian migrations of earlier times 
seem to have been impelled by similar dry periods. 

At a later time two similar invasions took place. First, from 
about 1000 A.D. to 1200 A.D. the climate of central Asia seems 
to have grown decidedly drier, and distress and discontent 
reigned among the people of the tents. At this time, as in the 


days of Mohammed, no great concerted movement might have 
arisen, had it not been for the ambitions of one man. Jenghiz 
Khan may have been no more ambitious and no abler than other 
gifted men of his race, but he happened to live at a period when 
natural calamities had brought his people to a condition of dis- 
content favorable to his aspirations. This condition, it would 
seem, was an important help in enabling him in a few years to 
arouse all the tribes of the steppes and deserts, and sweep over 
Asia, bringing almost unparalleled devastation. Three centuries 
later, at the beginning of the sixteenth century, another ambi- 
tious Asiatic, Baber by name, arose in Turkestan and emulated 
his great ancestor Jenghiz Khan. In Baber's case, also, physical 
conditions seem to have favored his projects, for after a period 
of improved climate, a rather rapid decrease in rainfall cul- 
minated at the time of his conquests. How much this had to do 
with the fact that he was able to conquer India and establish 
there the Mogul dynasty has not yet been thoroughly investi- 
gated. It seems clear, however, that this dry period should at 
least be carefully considered before any conclusions are drawn 
as to Baber and the Mogul conquest of India. 

From great wars and movements of the nations let us turn 
back to the individual people, and see how increasing aridity 
may effect a race physiologically. The chief effect is probably 
produced by the selective action of disease. Insidious diseases 
such as malaria, consumption, neurasthenia, and the like are 
presumably among the most important sifters of the wheat from 
the chaff in the physical make-up of a nation. Although malaria, 
for example, docs not kill people in any such spectacular fashion 
as do the great epidemics, it may be far more dangerous in its 
ultimate effects. The plague passes over the land and is gone; 
the dead are dead, and the living have suffered no serious injury. 
Malaria on the contrary, hangs on year after year, not killing 
its victims, but sapping their energy and vitality. The presence 
and the abundance of malaria are closely associated with cli- 


mate and topography. Without entering into any discussion of 
the origin of malaria, let me point out how a change toward 
aridity in a country like Greece and, to a less extent, Italy, 
would probably foster the disease. 

Malaria is preeminently a disease of tropical and subtropical 
countries whose climate is characterized by alternate wet and 
dry seasons. Except in the perennially moist portions of the 
tropics, the streams of such regions are subject to seasonal 
floods which spread over wide areas for a short period and then 
disappear, leaving innumerable stagnant pools and swamps, 
ideal breeding places for the anopheles mosquito. Permanent 
bodies of water usually contain fish which eat the mosquito 
larvae and reduce their numbers, or else the water moves suffi- 
ciently to carry away most of the eggs that are laid in it. When 
the climate of a subtropical country becomes drier, the condi- 
tions which favor the mosquito arc intensified. This is due in 
large measure to the fact that a diminution of the rainfall les- 
sens the amount of vegetation upon the slopes and thus allows 
the soil to be washed away rapidly. The streams are thereby 
overloaded and begin to fill the valleys with sand and gravel. 
This causes the flowing water to wander hither and thither over 
broad flood plains in innumerable channels, which form pools 
when the floods assuage. Or it may be that the water loses 
itself in marginal swamps. The streams also become intermittent, 
and no longer contain large quantities of fish. Thus everything 
cooperates to reduce the number of streams which flow steadily 
throughout the year, and to increase the number of bodies of 
stagnant water in which the mosquitoes may live. This in itself 
may produce most widespread effects. How great they are may 
be judged from the success of the United States government in 
eradicating malaria at Panama by the opposite process of 
reducing the number of places where mosquitoes can breed. 

At the present time malaria is endemic in Greece and Rome. 
That is, it is always there, and is looked upon as one of the 


necessary diseases of childhood, much as we look upon measles. 
Sir Ronald Ross of the Liverpool School of Tropical Medicine 
is responsible for the statement that nearly half the people of 
Greece have suffered genuine injury from malaria, and in Italy 
the case is scarcely better. Up to the age of puberty children 
are attacked by it every autumn. They grow weak and sallow, 
their spleens are permanently enlarged, and their vitality is 
lowered for life. No one who has known much of malaria will 
question the severity of its results and the length of time which 
elapses before they are eradicated even in the case of adults. 
In spite of quinine, which has come to our aid in modern days, 
malaria is one of the most insidious of diseases. Every traveler 
who is really familiar with the Orient knows how the sufferers 
from malaria lie and groan for days, and may have little energy 
for months. They go languidly to the necessary tasks, and as 
soon as possible sit down to rest with open, stupid mouths. Phy- 
sicians agree that it is impossible to expect much initiative or 
energy from a nation in which for centuries almost half of every 
generation has been devitalized by this baneful disease. 

From a .painstaking study of classical authors W. H. S. 
Jones* has concluded that up to about 400 B.C. in Greece and 
200 B.C. in Rome, malaria was almost unknown. Then it ap- 
peared, and during the succeeding century or two became com- 
mon. At first it attacked adults, which shows that it was a rela- 
tively new disease, which was still epidemic and not endemic, 
or else, we would add, that Greece was on the very border of its 
habitat. Later it became permanently located in the respective 
countries and attacked chiefly children, the older people having 
become immune after suffering in childhood. It is noticeable that 
the introduction of malaria coincides with the beginning of the 
weakening of Greece and Rome, and the time when it became 

* Malaria: A Neglected Factor in the History of Greece and Rome. 
Cambridge, England, 1907. 


endemic, in Greece at least, is synchronous with the epoch when 
the luster of the ancient names became irretrievably dimmed. 

Ross and Jones are of the opinion that, along with various 
other factors, malaria was one of the important causes of the 
fall of Greece and Rome. The growing effeminacy and lightness 
of the Greeks, and the brutality of the Romans, are just the 
effects which they think would be produced upon people of the 
respective temperaments of the two races. The case is so strong 
that one can scarcely resist the conclusion that this pathological 
factor may have played an important part in the psychological 
changes which appear to have accompanied the decline of civili- 
zation and of population in both Greece and Rome. It would 
be unwarranted to assert that the increase in the amount and 
severity of malaria was due wholly to climatic changes. Other 
influences, such as contact with Egypt and the introduction of 
slaves, may have been equally effective. Nevertheless, it seems 
probable that the spread of the disease in both Greece and Rome 
proceeded most rapidly when a change of climate not only ren- 
dered the topography of the valleys and the behavior of the 
streams more favorable than hitherto to the propagation of 
the anopheles mosquito, but likewise weakened the physique of 
the people so that they readily succumbed to disease. 

Natural selection presents a still more insidious way in which 
the change from relatively moist, stormy, cool conditions to 
those of aridity may have affected the Greek, Roman, and other 
races. In the opinion of many scholars one of the most important 
factors in the greatness of these powers was the presence of a 
race of blond northern invaders. Take the case of Greece. These 
northern Achseans apparently came into the country in the 
thirteenth century B.C. Their coming may have been influenced 
by the dry period of which we find some evidence at that time 
both in America and Asia. After their arrival the climate on 
the whole, although with many fluctuations, appears to have 
become more propitious. Up to the third century it continued 


to be favorable. Then it became more arid. We have seen how 
sensitive people are to climatic environment. The negro would 
apparently disappear in the northern United States were he not 
replenished from the South. The Scandinavian does not seen) 
to prosper greatly in the dry, sunny portions of the United 
States ; he is there subject to diseases of the skin and nerves 
which appear seriously to deplete his numbers in a few genera- 
tions ; whereas in the rainy Northwest, which resembles his 
native habitat, he thrives greatly both in body and estate. It 
was probably the same with the northern invaders in Greece, 
So long as the climate was propitious they flourished and lent 
strength to the country. Then, when conditions became less 
favorable, the unseen ravages of malaria and other diseases 
presumably attacked them with especial severity, and in the 
course of centuries they gradually disappeared. Today blond 
Greeks are almost unknown, although classical literature and 
many fair-haired old statues demonstrate their presence for- 
merly in considerable numbers. 

Thus far we have been discussing changes of climate, and 
have overlooked the fact that even though the climate remains 
constant, man's cultural progress may alter the location of 
the most favorable climate and hence of the centers of civiliza- 
tion. This depends upon the fact that the climate which is most 
favorable to a race in a primitive stage of development is not 
the most favorable for the same race in a higher stage of culture. 
GilFillan, in an article on "The Coldward Course of Progress,"* 
has presented an interesting study of the way in which man's 
cultural heritage, in the form of a constantly growing command 
over nature, has enabled mankind to advance farther and farther 
into regions of low winter temperature. In a savage state, with- 
out fire, clothing, or shelter other than caves, man is not likely 
to thrive where the winter temperature remains for any length 

* Political Science Quarterly, 1920. The same subject is discussed from 
another standpoint in Stefansson's The Northward Course of Empire. 


of time as low as freezing, and his main development is almost 
sure to be where the coldest months are not much below the 
physical optimum of 64 or 65 F. With each step of progress 
he is able to endure greater extremes of climate. The open fire, 
the grate, the stove, the furnace, and the central heating plant 
are all steps toward a condition where man is able to resist the 
cold, no matter how severe it may be. The use of the skins of 
animals for clothing ; the invention of the arts of spinning and 
weaving; the domestication of the sheep, goat, and camel; the 
cultivation of flax, and especially cotton ; the invention of power 
looms and of the steam engine ; all these are important steps 
which have tended to make man independent of climate. So too 
are the inventions which enabled mankind to close the mouths of 
the caves in which he lived, and then to build huts, thatch them, 
cover them with close-fitting shingles, construct them of thick 
bricks, or otherwise make them warm and weatherproof. In like 
manner man's power to resist unfavorable climates has been 
increased by every invention that has made it possible to trans- 
port food cheaply and quickly, and to preserve it for long 
periods. Today it is not difficult for large communities to live 
in health and comfort in the cold parts of the earth where their 
naked ancestors would have perished in a few days. Human 
energy may perhaps ultimately rise higher in those regions than 
in others, for many of the diseases of warmer regions do not 
flourish there, and the constant changes from the warmth within- 
doors to the cold without seem to be highly stimulating and 
healthful, provided they are properly guarded against. More- 
over, in cold regions man can be free from the effects of undue 
heat against which he has thus far shown little ability to pro- 
tect himself. Thus it appears that even without changes of 
climate the highest civilization would have tended gradually to 
migrate farther and farther north. How far this tendency will 
go is not yet clear, but the far northern location of such pro- 
gressive people as the Scotch, Canadians, Swedes, Norwegians, 


Icelanders, and Finns seems to suggest that the limit has not 
yet been reached. 

One other phase of GilFillan's work deserves careful notice. 
He points out that when civilization takes a backward step it 
also tends to move equatorward. For instance, about two hun- 
dred years before Christ the leadership of the world had passed 
from Greece, while Rome was falling into a state of confusion 
and retrogression from which its recovery was never complete, 
even in the days of Augustus. At that time the intellectual 
leadership went back toward the south, and the Alexandrines 
held aloft the torch of learning. They did not, to be sure, make 
any great intellectual or material innovations, but they at least 
kept the spirit of progress alive. In the same way in the Dark 
Ages the intellectual leadership of the world went back to North 
Africa where lived such men as Saint Augustine and his con- 

GilFillan suggests an interesting explanation of what happens 
when the most progressive nations of any given period are 
suddenly thrown backward by barbarian invasions, climatic 
changes, or similar occurrences. At such times regions which 
have formerly ranked high stand out once more as leaders. 
When the cooler countries fall to a low estate, the eclipsed 
warmer countries come into prominence. They still represent the 
highest type of civilization that is compatible with their climate, 
even though they have not been able to make that type appear 
great or important because the cooler and more energetic 
countries have not given them a chance. Thus in the Alexandrine 
period, when Greece had fallen and even Rome was at a low ebb, 
northern Egypt took the lead because the stage of progress to 
which the world had regressed was suited to Egypt's climate. 
How true this hypothesis may be, it is hard to say. The migra- 
tion of the more competent Greeks to Egypt may explain the 
Alexandrine period. Greece was becoming uninhabitable and 
poverty stricken by reason of an adverse climatic change, but 


Egypt with its perennial river was still prosperous and attrac- 
tive. Nevertheless, there seems to be much truth in the idea that 
man's social progress constantly alters his relation to climate. 
In the past great inventions have helped chiefly in enabling man 
to overcome low temperature; in the future, perhaps, they will 
help him in equal measure to overcome high temperature, dry- 
ness, and monotony. 

The last matter to engage our attention is the effect of 
changes in storminess. In reading what has been said about 
Egypt, for example, the reader has probably said to himself: 
"This book claims that the people there were once energetic and 
healthy because of frequent storms. If this is so, the rainfall 
must have been much more abundant than now. For the sake 
of argument we grant that at certain periods the precipitation 
was greater than at present, but we cannot possibly believe 
that it increased to the extent demanded by this hypothesis." 

This objection is so important that I have made a special 
investigation to determine the exact relation between stormi- 
ness and rainfall. The word storm, as already explained, does 
not primarily mean rain. To the meteorologists a storm is an 
area of low barometric pressure which is always accompanied 
by inblowing winds, and usually, but not invariably, by rain, 
Even if there is not a drop of rain, a storm may otherwise be 
fully developed and may cause strong winds which give rise to 
changes of temperature and humidity. The matter is well illus- 
trated by comparing Colorado and Georgia. According to Kull- 
mer's maps, Colorado is one of the stormy parts of the United 
States. It is crossed by the centers of about three times as many 
storms as Georgia. Yet its rainfah 1 is only about one third as 
great. In other words, Georgia has nine times as much rain in 
proportion to its storms. The reason is simple. Colorado lies 
far from the ocean, and the air which rises in the centers of 
its areas of low pressure has already lost most of its moisture. 
Georgia, on the other hand, lies so near the broad Atlantic 


and the warm Gulf of Mexico that storms draw in great quanti- 
ties of moisture. The lands around the eastern Mediterranean 
and in western Asia have a climate far more like that of Colo- 
rado than of Georgia. Part, to be sure, are near the Mediter- 
ranean Sea, but that furnishes only a little water compared 
with the great oceans. 

Another comparison shows that in the entire United States 
if the number of storms increases 20 per cent during a given 
series of years, the rainfall increases scarcely 10 per cent. In 
the arid southwest, however, the ratio is larger, the increase in 
storminess for all available stations being three times as great 
as the increase in rainfall. These figures apply to present con- 
ditions where the variations are slight and of short duration. 
If larger, more permanent changes took place, the rapidity of 
the atmospheric circulation would probably be so much in- 
creased that the ratio between increase in storminess and in rain- 
fall would be greater than at present, and might be four, or 
even six to one. The drier the region, the greater would probably 
be the ratio. 

Suppose that the ratio were four to one in Syria. A change 
which would increase the storminess by 200 per cent would 
involve a change of rainfall amounting to 50 per cent. That is, 
the number of stimulating changes would be three times as 
great as now, while the rainfall would only increase by one half. 
Such a change would render the Phoenician coast much more 
stimulating than at present. It would also increase the agri- 
cultural wealth, and would cause the limits of permanent habi- 
tation to advance some miles into the desert. There the stimu- 
lating influence might be less than on the coast, because the 
storms might be somewhat interrupted by crossing the moun- 
tains. Nevertheless, it would be important. The effect of in- 
creased storminess upon habitability, however, would be much 
less noticeable than upon energy or than in better watered 
regions. An increase of 50 per cent in a rainfall of twenty 


inches, such as is now enjoyed by many parts of Syria, would 
raise the precipitation to thirty inches, a figure which permits 
great prosperity. A corresponding change in Egypt would in- 
crease the rainfall of Alexandria from 8.8 inches to 13.2, that 
of Port Said from 3.3 to 5, and that of Cairo from 1.3 to 2. 
Farther east in Mesopotamia, Bagdad would change from 9 to 
13.5, while in Persia, Teheran would rise from 10 to 15 and 
Ispahan from 5.2 to 7.8. Deserts would still be deserts. They 
would be easier to cross than at present, and the number of 
inhabitants might be greater, for there would be more pasturage 
for camels and sheep. The springs would also be larger and more 
permanent than now, and some new ones would appear. Yet the 
predominant feature would still be great wastes of blowing sand 
and barren gravel ; the people would have to be nomads ; and 
those who entered the desert would frequently encounter rigors 
like those of today. Thus a large change in the stimulating quali- 
ties of a subarid or desert climate is possible without a change 
of rainfall greater than that for which there seems to be good 

Consider more specifically exactly what happens when stormi- 
ness increases in regions such as western Asia and eastern Cali- 
fornia. The general conditions at the time when Greece was in 
its prime, for example, appear to have been approximately as 
follows: (1) The average temperature for the year as a whole 
was probably a little lower than at present, but it is doubtful 
whether the difference amounted to more than two or three 
degrees at most. (2) The temperature of the seasons may have 
varied somewhat more than that of the year as a whole. The 
greater mixing of the air from wide areas by means of the winds 
that accompany storms presumably lowered the summer tem- 
perature a little over the lands and raised the winter tempera- 
ture. (3) The amount of rain was apparently considerably 
greater than now. Doubtless the rain then, as now, came chiefly 
in winter, while the summers were very dry just as at present, 


but the length of the rainy season appears to have been in- 
creased. That is, the rains began earlier in the autumn and 
lasted longer in the spring than at present. (4) The amount of 
atmospheric moisture over the lands was presumably greater 
than now. This would arise partly from the increased cloudiness 
and rainfall and partly from the fact that the winds were pre- 
sumably more efficacious in bringing moisture from the neighbor- 
ing seas. (5) The winds were apparently stronger than at pres- 
ent, arid varied in direction much more than now because of the 
frequent storms. (6) The greater storminess and the more fre- 
quent changes in the winds, as well as their greater strength, 
must have caused great or at least frequent variability of tem- 
perature as well as variations in other respects. Such variability 
would occur even in summer when the storms passed to the north 
of the lands that were most progressive two or three thousand 
years ago; it would be still more pronounced in the rainy 

Let us apply these generalizations to a specific case. Suppose 
that from 500 to 400 B.C. the climate of Athens differed from 
that of the present in the following respects : 

1. Temperature of July 77 F. instead of 81 F.; January 
48 instead of 46. Mean temperature of the year 62.0 instead 
of 63.1. 

2. Relative humidity at all seasons 10 per cent higher than 
now, January the moistest month, 84 per cent instead of 74 per 
cent ; July the driest month, 58 per cent instead of 48 per cent. 
As a matter of fact the change was probably not the same at 
all seasons, but I wish to keep our example simple. 

3. Annual rainfall 22 inches instead of 15, ranging perhaps 
from 3.3 inches in November to 1.0 in July instead of 2.9 in 
November and .03 in July. 

4. Number of storms twice as great as now. 

Such a change seems conservative. It is scarcely more than 


the normal variation from one year to another. Nevertheless, 
when we calculate its effect upon health in the same way that 
we have calculated the data for our map of climatic energy 
based on the effect of the seasons in American cities (Figure 86), 
the result is astonishing. From a climatic level only equal to that 
of Augusta in Georgia and Vicksburg in Mississippi, Athens 
rises to a level practically the same as that of New York and 
Chicago, the best regions in North America aside from the coast 
near Newport; a slight farther increase in storminess or a 
farther lowering of the summer temperature two or three de 
grees more would make Athens rival Paris and Berlin; and if 
the storminess should be three times as much as at present, which 
would be a small matter compared with the differences between 
one year and another at places like San Francisco, the heali fa- 
fulness and stimulating qualities of the climate of Athens would 
rival those of southeastern England, which seems to be well- 
nigh the most favored place in the whole world. When we recall 
that according to Figure 41 the estimated death rate in Greece 
is nearly twice that of England, the significance of such a 
change is apparent. It would presumably get rid of malaria to 
a large extent ; it would stimulate the Greeks to a degree of 
persistent activity quite foreign to the country at present ; it 
would raise the economic level and correspondingly improve the 
diet of the people ; and it would give to the Greeks a spirit of 
enterprise, a physical vigor, and a mental activity which would 
probably soon enable them to take advantage of all sorts of 
modern discoveries which they now use half-heartedly and in- 
effectively, if at all. The slightness of the climatic change neces- 
sary to produce important results seems to give to the conclu- 
sions set forth in the present edition of this book a reliability 
much greater than was possible in the first edition, before the 
health of American and European cities had been studied in its 
relation to the weather. 

As we come to the end of this volume I am well aware that to 


those who accept the climatic hypothesis, it may seem depress- 
ing. To the dweller in the less favored parts of the world it 
may appear to sound the knell to his hopes for great progress 
in the land that he loves. To his brother in the center of modern 
activity a most disquieting vision of possible retrogression is 
disclosed. If our reasoning is correct, man is far more limited 
than he has realized. He has boasted that he is the lord of 
creation. He has revelled in the thought that he alone among 
created beings can dwell in the uttermost bounds of the earth. 
One more of the bulwarks of this old belief is now assailed. Man 
can apparently live in any region where he can obtain food, but 
his physical and mental energy and his moral character reach 
their highest development only in a few strictly limited areas. 
The location of those areas appears to have varied greatly in 
the past ; it may vary greatly in the future. In a thousand years, 
for all that we can tell, so the prophet of evil will say, no 
highly favorable region may exist upon the globe, and the 
human race may be thrown back into the dull, lethargic state 
of our present tropical races. Even without so dire a calamity, 
the location of the regions of greatest climatic energy may in 
a few hundred years change again to Egypt, Mesopotamia, and 
Guatemala. The consequent rise of new powers and the decline 
of those now dominant may throw the world into a chaos far 
worse than that of the Dark Ages. Races of low mental caliber 
may be stimulated to most pernicious activity, while those of 
high capacity may not have energy to withstand their more 
barbarous neighbors. 

Even if such extreme disasters should not occur, the prospect 
is depressing. Take such a favored country as the United 
States. In the South we find less energy, less vitality, less edu- 
cation, and fewer men who rise to eminence than in the North, 
not because southerners are in any way innately inferior to 
northerners, but apparently because of the adverse climate. In 
the far West people seem to be stimulated to such a degree that 


nervous exhaustion threatens them. In the North we see still 
another handicap. In spite of a wonderfully stimulating climate 
most of the year, the people suffer sudden checks because of the 
extremes of temperature. These conditions favor nervousness, 
and worst of all they frequently stimulate harmful activities. 
That, perhaps, is why American children are so rude and bois- 
terous, or why so staid a city as Boston has six times as many 
murders as London in proportion to the population. Our coun- 
try takes immigrants of every mental caliber, and then stimu- 
lates some to noble deeds and others to commit murder, break 
down the respect for law, and give us city governments that 
shame us in the eyes of the world. All these things would appar- 
ently not happen to such an extent were our climate less bracing 
and did not its extremes often weaken the power of self-control. 
Other lands also have their drawbacks. Germany is much like 
the eastern United States, although not so extreme. France on 
the other hand is less stimulating. England suffers from too 
great cloudiness, and in Ireland this becomes a factor of serious 
import. If the best parts of the earth have such climatic dis- 
advantages, what shall we say of Russia, weighted down with 
benumbing cold and comparative monotony or with changes so 
extreme that they are harmful? What of China under a much 
heavier handicap of monotony ; or of tropical lands burdened 
most heavily of all? If climatic conditions influence character 
as we have inferred, does not our hypothesis weaken man's moral 
responsibility? Will not people more than ever ascribe their 
failings to nature, and so excuse themselves? In the favored 
regions will not men become increasingly arrogant and over- 
bearing, because they will be surer than ever that the rest of 
the world cannot resist them? If all these sad results are possible, 
is it well to know that climate so strongly influences us? We 
cannot change the climate, so why ascribe to it such great effects 
merely to destroy hope in some and moral responsibility in 
others ? 


The answer to these questions may be put in the form of a 
parable. Ages ago a band of naked, houseless, fireless savages 
started from their warm home in the torrid zone, and pushed 
steadily northward from the beginning of spring to the end of 
summer. They never guessed that they had left the land of con- 
stant warmth until in September they began to feel an uncom- 
fortable chill at night. Day by day it grew worse. Not knowing 
its cause they traveled this way or that to escape. Some went 
southward, but only a handful finally returned to their former 
home. There they resumed the old life, and their descendants 
are untutored savages to this day. Of those who wandered in 
other directions all perished except one small band. Finding 
that they could not escape the nipping air, the members of this 
band used the loftiest of human faculties, the power of conscious 
invention. Some tried to find shelter by digging in the ground, 
some gathered branches and leaves to make huts and warm beds, 
and some wrapped themselves in the skins of the beasts that 
they had slain. Soon these savages had taken some of the greatest 
steps toward civilization. The naked were clothed ; the houseless 
sheltered ; the improvident learned to dry meat and store it with 
nuts for the winter, and at last the art of making fire was dis- 
covered as a means of keeping warm. Thus they subsisted where 
at first they thought that they were doomed. And in the process 
of adjusting themselves to a hard environment they advanced 
by enormous strides, leaving the tropical part of mankind far 
in the rear. 

Today mankind resembles these savages in certain respects. 
We know that we are limited by climate. As the savages faced 
the winter, so we are face to face with the fact that the human 
race has tried to conquer the arctic zone, the deserts, and the 
torrid zone, and has met with only the most limited success. 
Even in the temperate zone he has made a partial failure, for 
he is still hampered in hundreds of ways. Hitherto we have 
attributed our failure to economic conditions, to isolation and 


remoteness, to racial incapacity, or to specific diseases. Now 
we see that it is probably due in part to lack of energy or to 
other unfavorable effects produced directly upon the human 
system by climate. This is no reason for despair. We ought 
rather to rejoice because, perhaps, we may correct some of the 
evils which hitherto have baffled us. 

Again and again in our discussion of factories and other 
matters we have come upon ways in which a change in our 
methods may do much to overcome the harmful effects of cli- 
mate. I do not propose to enumerate them, for the specific 
application of our results may well be deferred until we know 
whether our main hypothesis is likely to stand. Yet one or two 
general lines of progress may properly be pointed out. Take 
the harmful winters of the northern United States. It is highly 
probable that the loss of energy which occurs at that time may 
be largely avoided, or at least greatly diminished. Much of it 
arises from the fact that after the wonderfully stimulating 
autumn weather, when we have been living under almost ideal 
conditions of mean temperature, of humidity, and of variability 
from day to day, we suddenly begin to heat our houses. We 
create an indoor climate of great uniformity, of unduly high 
mean temperature, and of the most extreme aridity. All these 
conditions are harmful. If our houses were kept at lower tem- 
peratures, if the temperature were varied from day to day, and 
if the humidity were kept at the optimum, we should increase 
our efficiency greatly. We should be comfortable, also, for with 
proper humidity, and with changes from day to day, we should 
not feel the need of the high temperatures which we now require 
because the extreme dryness forces the body to give up much 
more heat than would be demanded by air of greater humidity. 
Moreover, the uniform dryness within doors does almost untold 
harm in parching the mucous membranes and thus rendering us 
peculiarly liable to colds, grippe, and similar ailments which 
often lead to serious diseases such as pneumonia and tubercu- 


losls. Of course we could not entirely avoid colds by the method 
here suggested, but we surely could diminish them. In the 
autumn before our houses are heated, colds are comparatively 
rare, and the same is true among people who live out of doors 
in winter. If the conditions inside our houses could be like those 
that prevail in the autumn, the general health of the community 
would probably be much improved. In this one way there might 
be a saving not only of millions of dollars' worth of valuable 
time, but of an immense amount of nervous energy which is 
wasted because persons who are irritated by colds do or say 
things that they would scorn under normal conditions. 

Along still other lines great improvements might be possible. 
For instance, in many factories the same amount of work is 
expected each month. Hence, at certain seasons many opera- 
tives, especially girls, work harder than they ought, while at 
others they do not work so hard as they easily could without 
special effort. If factories were run in accordance with a well- 
established seasonal curve of energy, we should find the ma- 
chinery running slowly in winter, faster in the spring, and in 
May perhaps 10 or 15 per cent faster than in January. Then 
in the summer it would run more slowly than in May, but not 
so slowly as in winter. Finally, in the autumn it would run at 
greater speed than at any other time of year. The operatives 
would scarcely be conscious of the difference, and they would 
probably do more work and preserve their health better than 
under the present system. 

If our hypothesis is true, it is likely to prove helpful not only 
to places where the climatic disadvantages are slight, but where 
they are great. Consider regions which have a winter of great 
severity, but an invigorating summer. Contrast them with 
places where the summer is too hot, but the winter favorable. 
Russia and Mesopotamia may serve as examples. Today we 
already have a small number of people who move back and forth 
each year between places of this sort, for instance northern 


Germany and the Riviera, New England and Florida. Unfor- 
tunately, those who do this are usually not the workers, but the 
idlers or those whose work is almost finished. In the future, 
however, if the principles here laid down find acceptance, we 
may expect that such interchanges will take place on a scale 
to stagger the imagination. Not only the leisure classes, but 
laborers and farmers may thus move back and forth. In winter 
most of Russia's peasants have little to do, and their enforced 
idleness is harmful. They might go to Mesopotamia where most 
of the farm work is done between October and May. If people 
could move thus from place to place, not only would there be 
an enormous increase in production, but many other benefits. 
The part of the population that moved would be stimulated, not 
only by the change of climate, but by contact with other races 
and new methods. They would be more tolerant, more pro- 
gressive, and more eager for education. Both countries would 
benefit by such an interchange of workers, and much of the 
handicap of places like Russia might possibly be overcome. 
Perhaps the day will come when only the poorest families will 
stay in an unfavorable climate more than a few years at a time 
without going at least for a season to some place where they 
will receive new stimulus. 

In tropical countries the chances for improvement are at a 
maximum. Already most Europeans and a few natives appre- 
ciate the necessity for spending part of the year among the 
mountains or in a climate different from that where they usually 
live. For the most part the lowlanders go to the highlands, but 
in lofty plateaus like Mexico it is not uncommon for foreigners 
to take a run down to the coast for a change of air. Of course 
altitude has much to do with this, but even though Vera Cruz 
has a bad climate for permanent residence, it is stimulating for 
a short while when one comes from a wholly different environ- 
ment. In the future we can scarcely doubt that this method of 
overcoming the evil effects of a tropical climate will be resorted 


to on a vast scale, not only by foreigners, but by the more 
intelligent portion of the natives. 

In the warmer parts of the earth there in another side to the 
question. Mankind needs not only seasonal changes, but varia- 
tions from day to day, or week to week. Two methods of obtain- 
ing these suggest themselves. One is by cooling the interiors of 
houses. Today this is done on a small scale by shutting out the 
sun and sprinkling water to cause evaporation. There is no 
reason why the same result should not be produced on a large 
scale. We already know how to cool houses as well as to heat 
them. We do it in ice-plants. A thousand years ago men would 
have laughed at the idea that hundreds of rooms would some 
day be heated by a single fire, yet we see it in every office building 
or hotel. In equatorial regions there is as much reason for 
equipping the houses with coolers as there is in temperate regions 
for equipping them with heaters. In both cases uniformity of 
temperature is apparently a mistake, for moderate changes 
from day to day appear to be favorable. Even though a man's 
work may be out of doors, it seems probable that he would be 
much stimulated and much better enabled to work hard in the 
heat if he could sleep in a comparatively cool house. If he lives 
where the climate is too damp, he would be benefited by having 
the house relatively dry, just as the northerner in winter appar- 
ently ought to have his house more moist than is now his habit. 
Both need to enjoy the optimum conditions. 

A second method of obtaining frequent changes may possibly 
prove of much importance. Today the seacoast in many regions, 
for example on the Atlantic shore of America from New York 
to Boston, is bordered by an almost continuous line of houses. 
At first people went to these only in the summer. Now many 
go for week-ends at almost all seasons. Fifty years ago such a 
thing was almost unknown. Fifty years hence it will probably 
be many times more prevalent than now. In tropical countries 
millions of people may not only move to other climates during 


part of each year, but many may move back and forth from the 
lowlands to the highlands every few days. Their work may be 
arranged so that almost every family can spend week-ends in 
the highlands and the rest of the time in the lowlands. In Sar- 
dinia, in order to escape the malaria of summer, many villages 
are today completely duplicated in the lowlands and highlands, 
churches, houses, shops, everything in duplicate. Moreover, 
aside from farming, mining, lumbering, and the like, most of the 
other kinds of work can be located where the climatic conditions 
are best, a matter which is becoming increasingly easy as our 
facilities for communication improve. Yet if these are to be 
within the tropics, the people engaged in them must have an 
opportunity to obtain the stimulus of changes. Perhaps they 
will frequently go from their places of work in the highlands to 
the neighboring lowlands or to the high mountains. 

The expense of such a system of having two homes for a large 
part of the population will doubtless be enormous, but that is 
relatively unimportant. If the farmers of the tropics were as 
efficient as those of the temperate zone, one man's labor would 
produce two or three times as much as in Europe or the United 
States. If white men can devise a means whereby they can live 
in the torrid zone and retain approximately the energy which 
they possess in their own countries, or if they can largely in- 
crease the efficiency of the natives, they can afford to spend 
t-normous sums in creating favorable conditions. How we shall 
go to work in detail cannot yet be determined, but that will 
easily be discovered. For the present it is enough to see that 
the hypothesis of climate as a condition of civilization is far 
from depressing. It holds out hope that the inhabitants of even 
the most favored parts of the temperate zone may improve their 
condition. It holds out still more hope that the people of the 
less favored parts of that zone and of the subtropical zone may 
be benefited. And it holds out far the greatest hope to those 


who dwell in the tropical regions which now are the most hope- 

If our hypothesis is true, man is more closely dependent upon 
nature than he has realized. A realization of his limitations, 
however, is the first step toward freedom. In suggesting pos- 
sible ways of obtaining a new ascendancy over climatic handi- 
caps we have dealt largely with material matters. Bound up 
with these, and far more important, are great moral issues. We 
are slowly realizing that character in the broad sense of all that 
pertains to industry, honesty, purity, intelligence, and strength 
of will is closely dependent upon the condition of the body. Each 
influences the other. Neither can be at its best while its com- 
panion is dragged down. The climate of many countries seems 
to be one of the great reasons why idleness, dishonesty, immo- 
rality, stupidity, and weakness of will prevail. If we can con- 
quer climate, the whole world will become stronger and nobler. 





J. Barrell, geologist, New Haven, Conn. 

P. Bigelow, traveler and author, Maiden, N. Y. 

I. Bowman, geographer, New York, N. Y. 

W. M. Brown, geographer, Providence, R. I. 

R. D. Calkins, geographer, Mt. Pleasant, Mich. 

J. S. Chandler, missionary, Madura, India. 

A. C. Coolidge, historian, Cambridge, Mass. 

S. W. Cushing, geographer, Salem, Mass. 

L. Farrand, anthropologist, Ithaca, N. Y. 

C. W. Furlong, traveler and author, Boston, Mass. 

H. Gannett, geographer, Washington, D. C. 

E. W. Griffis, traveler and author, Ithaca, N. Y. 

A. Hrdlicka, anthropologist, Washington, D. C. 

E. II . Hume, physician and missionary, Changsha, China. 

E. Huntington, geographer, New Haven, Conn. 

M. Jefferson, geographer, Ypsilanti, Mich. 

A. G. Keller, anthropologist, New Haven, Conn. 

E, F. Merriam, editor, Boston, Mass. 

J. H. Potts, missionary, Shanghai, China. 

E. Sapir, anthropologist, Ottawa, Canada. 

J. R. Smith, economic geographer, New York, N. Y. 

E. V. Robinson, economic geographer, Minneapolis, Minn. 

W. S. Tower, geographer, New York, N. Y. 

R. H. Whitbeck, geographer, Madison, Wise. 

S. W. Zwemer, missionary, Cairo, Egypt. 

Anonymous, New York City. 



George Black, Sydney, Australia. 

James Bryce, statesman, London. 

Leonard Darwin, soldier, London. 

T. H. Holdich, soldier, London. 

H. H. Johnston, administrator, Arundel, England. 

J. S. Keltic, geographer, London. 

T. S. Longstaff, geographer, London. 

D. Carruthers, explorer, Manningtree, England. 


S. de Geer, geographer, Stockholm, Sweden. 
H. F. Helmholt, historian, MUnchen, Germany. 

A. Kraemer, ethnographer, Stuttgart, Germany. 

Mrs. M. Krug-Genthe, geographer, Chemnitz, Germany. 

H. H. Reusch, geologist and geographer, Kristiania, Norway. 

H. ten Kate, anthropologist, Holland. 

F. von Luschan, anthropologist, Berlin, Germany. 
K. F. Sapper, geographer, Strassburg, Germany. 


D. n Anoutchine, geographer, Moscow, Russia. 

L. Gallois, geographer, Paris, France. 

V. Giuffrida-Ruggeri, anthropologist, Naples, Italy. 

G. Papillault, anthropologist, Paris, France. 

B. y Rospide, geographer, Madrid, Spain. 
G. Sergi, anthropologist, Rome, Italy. 

S. Telles, geographer, Lisbon, Portugal. 


Katsuro Haro, Imperial University, Kyoto, Japan. 
Inazo Nitobe, Imperial University, Tokyo, Japan. 
Naomasa Yamasaki, Imperial University, Tokyo, Japan. 
Jeme Tien-yow, Shanghai, China. 
Wang Ching-chun, Tientsin, China. 
Wu Ting-fang, Shanghai, China. 



Letters sent Replies Contributors 

Americans 64 57 25 

British 43 88 8 

Teutonic Europeans 42 28 8 

Latin Europeans . . 27 8 6 

Asiatics 21 8 6 

Non-Teutonic and non-Latin Europeans .10 2 1 

Latin Americans 6 2 

Total 213 138 54 


The following list contains the final results of the classifica- 
tion made by the preceding contributors. In examining this the 
reader should remember that the division into regions and the 
grouping of the regions according to race make no claim to 
perfection. Convenience in obtaining units small enough to 
give a detailed map and yet to be known to people of many races 
has been the primary object in dividing the different countries 
of the world into smaller sections. The sections are small in 
Europe and the United States because these regions are well 
known, and large in Siberia because very few people can dis- 
tinguish sharply between different parts of that country. In 
a few cases I have added minor divisions such as southern 
Alaska, with a special object not connected with the present 
book. The grouping by races in Europe, Asia, and North 
America has been guided also by motives of convenience. Such 
places as Ireland, Asia Minor, Bulgaria, Baluchistan, and 
others might properly be placed in other groups as well as in 
those where I have put them. The reader can easily rearrange 
for himself. My purpose has been merely to make a convenient 
classification for our immediate purpose without respect to its 
applicability elsewhere. 


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Mountainous part of Peru 

Mountainous part of Colombia 

Mountainous part of Bolivia 

Mountainous eastern region of Brazil (no 
tude 20 ^ 

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Guiana (French, British, and Dutch) . . . 

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NOTE. In the Andean countries of South America, except Chili, the 
most advanced districts are found in the highlands. The eastern lowland, 
which is heavily forested or else covered with savannah, contains only a 
scanty population composed almost wholly of Indians. The way in which 
each of these countries is divided into a "mountainous part," and an "east- 
ern lowland" seems to have created confusion in the minds of many con- 
tributors. They apparently thought of the lofty mountains, and not of the 
plateau as was intended. Hence they rank the lowlands higher than the 
mountains. As a matter of fact, the lowlands are in almost the same 
condition as the Amazon Basin (No. 185). Therefore, after the figures for 
Venezuela, Colombia, Peru, and Bolivia, I have added in parentheses a 
series of numbers indicating the rank of these countries if in each case the 
higher value in any given classification is taken as intended for the more 
advanced portion, that is, the highlands. The numbers in parentheses are 
probably nearer right than the others, and have been used in preparing the 
map of civilization, Figure 45, 




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UNITED STATES (Continued) A. B. C. D. 

34. Oklahoma 3.7 3.1 0.6 3.4 

35. Oregon 4.6 5.0 0.4 4.9 

36. Pennsylvania 5.6 5.5 0.1 5.6 

37. South Carolina 1.6 2.2 0.6 1.9 

38. South Dakota 3.8 3.7 0.1 3.7 

39. Tennessee 3.0 2.6 0.4 $.8 

40. Eastern Texas 3.1 2.8 0.3 3.1 

41. Western Texas 1.8 1.6 0.2 1.9 

42. Utah 2.4 2.3 0.1 2.5 

43. Vermont 4.4 4.7 0.3 4.4 

44. Virginia 3.8 3.8 0.0 3.9 

45. Washington 4.8 5.0 0.2 5.0 

46. West Virginia 2.5 2.9 0,4 2.8 

47. Wisconsin 5.4 5.8 0.4 5.6 

48. Wyoming 2.9 2.6 0.3 2.8 

49. Southern Alaska 1.5 1.2 0.3 1.5 


50. Newfoundland 1.9 2.0 0.1 2.0 

51. Prince Edward's Island . . 2.6 2.1 0.5 2.5 

52. Nova Scotia 3.8 3.4 0.4 3.6 

53. New Brunswick 3.3 2.9 0.4 3.2 

*54. Quebec, east of longitude 72 30' 3.1 2.6 0.5 3.0 

*55. Quebec, west of longitude 72 30' 4.1 2.6 1.5 3.4 

56. Ontario, east of Lake Huron . 5.4 4.7 0.7 5.1 

57. Ontario, north of Lakes Huron 

and Superior 3.0 2.0 1.0 2.6 

* In this case some contributors may have misunderstood what was 

intended. At least, several of them placed the part of Quebec containing 
Montreal lower than the sparsely populated portion from Quebec eastward. 

If each contributor's higher figure be taken as meant for the part of the 
province containing Montreal, the final numbers in column D become East 

Quebec 2.5 and West Quebec 3.9. I am strongly inclined to think that 
many of the Canadian figures are too low, because all but one of the 
contributors were from the United States. For this reason Canada is not 
included in Figure 43. 


a -0,0 

CANADA {Continued) A. B. C. D. 

58. Manitoba 3.5 4.4 0.9 4.0 

59. Saskatchewan, southern half, i.e., 

south of latitude ,55 ... 3.0 3.0 0.0 3.1 

60. Saskatchewan, northern half, 

i.e., north of latitude 55 . 1.3 2.0 0.7 1.7 

61. Alberta, southern half ... 2.9 2.9 0.0 3.1 

62. Alberta, northern half ... 1.7 1.7 0.0 1.8 

63. British Columbia, southern half 3.8 3.4 0.4 3.8 

64. British Columbia, northern half 1.3 1.9 0.6 1.7 


PORT IN 1910-1913 


a c. 

35 99.8% 21 93.5% 

34 92.8% 20 93.6% 

33 92.9% 19 93.6% 

32 92.9% 18 93.7% 

31 92.9% 17 93.8% 

30 93.0% 16 93.9% 

29 93.0% 15 94.0% 

28 93.1% 14 94.1% 

27 93.1% 13 94.2% 

26 93.2% 12 94.3% 

25 93.3% 11 94.4% 

24 93.3% 10 94.5% 

23 93.4% 9 94,6% 

02 93.4% 8 



c. c. 

7 94.9% 15 100.0% 

6 95.1% 16 99.9% 

5 95.3% 17 99.7% 

4 95.5% 18 99.3% 

3 95.7% 19* 98.9% 

2 95.9% 20 98.4% 

96.2% 21 97.9% 

96.5% 22 97.4% 

96.8% 23 96.9% 

2 97.1% 24 96.4% 

3 97.4% 25 95.9% 

4 97.7% 26 95.3% 

5 98.0% 37 94.6% 

6 98.3% 29 93.9% 

7 98.6% 29 93.2% 

8 98.8% 30 92.5% 

9 99.0% 31 91.7% 

10 99.2% 33 90.5% 

11 99.4% 33 89.0% 

12 99.6% 34 86.8% 

13 99.8% 36* 84.3% 

14 99.9% 3 81.0% 



Aboriginal America, 366 ff. 

Abyssinia, Christianity in, 301. 

Accad, 352. 

Accidents, and climatic changes, 336. 

Achaeans, 394; migrations of, 23 f. 

Adults, relation to weather, 199 ff. 

^Egean Sea, early culture of, 357. 

^Esthetics, importance of, 251. 

Afghanistan, 355. 

Africa, civilization in, 261 ; sheep and 
cattle in, 53 f.; status of, 298. 

Africans, in World War, 274. 

Age, relation to influenza, 188 ff. 

Agra, climatic energy at, 231. 

Agriculture, civilization and, 373; 
effect on natural selection, 370; in 
Bahamas, 47 f.; in Central Amer- 
ica, 328 ff.; in Guatemala, 330; iron 
tools and, 371; of whites vs. ne- 
groes, 37 ff. 

Alabama, Black Belt of, 312. 

Alberta, climate of, 224. 

Alcohol, in tropics, 71 f. 

Alexandria, Greeks in, 27; rainfall 
at, 200; rise of, 397. 

Algae, optimum temperature of, 129. 

Algonkian Indians, 369. 

Alps, climate of, 220. 

Altitude, physiological effect of, 77 f . 

Amaru, 342 f. 

Ambition, relation to national de- 
cline, 27. 

America, aboriginal, 366 ff. See also 
North America and South Amer- 

American Indians, standards of, 254. 

Amorites, 342 f . 

Amsterdam, death rate of, 62. 

Andean highlands, status of, 298. 

Anger, in tropics, 70 f . 

Anglo-Saxons, in cotton mills, 97 f. 

Animals, optimum temperature for, 

Annapolis, changes of mean tem- 
perature at, 140 ff.; students' rec- 
ords at, 14 f., 104 ff. 

Anopheles mosquito, 392. 

Antevs, E., cited, 320, 345 f. 

Anthropologists, and climatic 
changes, 18. 

Appetite, atmospheric pollution and, 

Arabia, ruins in, 367. 

Arabs, migration of, 388; religion 
among, 390. 

Archaeologists, and climatic changes, 
17 f. 

Argentina, climate of, 223 f.; index 
of civilization, 252; status of, 298. 

Aridity, effect on races, 394 f.; natu- 
ral selection and, 394; relation to 
Mohammed, 390. 

Aristotle, 3, 76. 

Arizona, climatic energy in, 231; 
rank in progress, 288. 

Arkansas, eminence in, 311. 

Aryans, 355. 

Asexual reproduction, 131. 

Asheville, climate of, 161. 

Asia, archaeological work in, 9; civi- 



lization in, 259 f.; climatic curve 
of, 8; climate energy in, 236; des- 
iccation of, 11; relation to ideal 
climate, 223 f., 226. 

Asia Minor, civilization in, 857; 
Greek settlement of, 24; stonni- 
ness in, 362. 

Asiatics, in World War, 274. 

Assyria, early greatness of, 356. 

Athens, ancient climate of, 401 f . 

Atlanta, weather and deaths in, 208, 
213 ; workmen in, 50. 

Atlantic City, climate of, 161. 

Atmosphere, chemical pollution of, 
169 f.; health and, 153 ff. 

Atmosphere and Man, committee on, 
187 ff., 194, 203. 

Atmospheric moisture, ancient, 401. 

Atmospheric pressure, effect of, 78, 

Attica, settlement of, 23 f . 

Augusta, climate of, 402; effect of 
seasons in, 93 ff., 97 f. 

Aujeh, 333. 

Australia, aborigines in, 378; civili- 
zation in, 260, 263 ; climate of, 223 ; 
death rate of, 67, 378; status of, 
297, 351 ; tropical, 58, 376 ff . 

Australians, nativity of, 882. 

Austria, climate of, 224. 

Austrians, in World War, 274. 

Baber, 391. 

Babylonia, 343; civilization in, 353; 
early greatness of, 856. 

Bacteria, humidity and, 190, 203; re- 
lation to influenza, 189. 

Bacterial infection, atmosphere and, 

Bahamas, climate of, 48 ff . ; white vs. 
colored, 83 ff., 46 ff. 

Balfour, A., cited, 44. 

Balikh River, 843. 

Baltic region, climate of, 224. 

Baltic Sea, ice in, 326. 

Baltimore, humidity and death rate 
in, 178; storminess at, 217. 

Baluchistan, 355. 

Bantus, 43, 45. 

Barbarians, migrations of, 11, 390. 

Barrell, J., cited, 338. 

Barrett Expedition, 7. 

Bartholomew, J. G., cited, 223. 

Basutos, Drakenberg Mountains, 43. 

Baths, stimulus of, 146. 

Beaches, at Owens Lake, 325. 

Beasts of burden, Indian civilization 
and, 371 ff. 

Beersheba, 333; drought at, 387. 

Belgium, in World War, 274. 

Berg, cited, 337. 

Berlin, climate of, 402. 

Berliner, cited, 14. 

Besson, L., cited, 174 f., 203. 

Big business, 350. 

Big trees, of California, 8 f., 820, 
341, 346. 

Binet tests, white vs. colored, 81. 

Birth rate, 25; in Australia, 378, 388. 

Bison, 373. 

Black Belt, 312. 

Blondes, in Greece, 23, 394. 

Blood, flow of, 166 ff. 

Blood pressure, 166 ff. 

Body temperature, 165. 

Bolivia, status of, 298. 

Bombay, climatic energy at, 231; 
death rate of, 62; deaths and 
weather in, 181. 

Bonuses, effect of, 89 f. 

Books, and climate, 61. 

Boston, climate of, 161; Health De- 
partment, 158; hospitals in, 21; 
humidity and death rate in, 178; 
influenza in, 185 f., 189; murders 
in, 404; operations in, 179 ff.; pneu- 
monia in, 177; school children in, 



158, stonniness at, 214 f.; weather 

and deaths, 205 f . 
Boys, in school, 283 f.; proportion 

in Australia, 380. 
Brass fittings, making of, 82 f. 
Breasted, J. H., cited, 342 f. 
Breath, carbon dioxide in, 133. 
Bridgeport, changes of temperature 

in, 139 ff.; factory operatives in, 

14 f., 80 ff. 
B right's disease, influenza and, 188 


Britain, climate and, 224. 
British, in World War, 2T4. 
British Columbia, climate and, 221, 

224; effect of temperature, 162; 

humidity and death rate in, 178. 
Brooks, C. E. P., cited, 8, 17. 
Brown, L., cited, 94. 
Bruckner, E., cited, 25. 
Brunhes, cited, 341. 
Brunnow, cited, 132. 
Bryce, J., cited, 288; letter of, 253. 
Buckle, cited, 3. 

Buddhism, 355; progress and, 301. 
Buffalo, deaths and temperature in, 


Burans, 237. 
Butler, H. C., cited, 344, 388 f. 

Cairo, rainfall at, 400; deaths in, 181. 

Calcium, in blood, 157. 

Calcutta, climatic energy at, 231; 
death rate of, 62. 

California, big trees of, 8 f ., 320 ; cli- 
mate of, 220, 225; climatic curve 
of, 8; eminence in, 308; nervous 
disorders in, 225; status of, 289, 
297, 351 f.; stonniness in, 334; 
temperature of, 164 f . 

Cambodia, storms in, 367. 

Cambridge, influenza in, 190. 

Campani, A., cited, 163. 

Campeche, malaria at, 829. 

Canada, climate of, 223 f.; loyalists 
in, 46; progress of, 396; provinces 
of, 429 f.; status of, 267, 297, 396. 
Canal Zone, 62, 64. 
Cancer, and influenza, 188 ff. 
Cape Horn, storminess at, 230. 
Carbon dioxide, in breath, 133. 
Carnegie Institution of Washington, 

7 f., 194, 320 f. 
Carpenters, seasonal work of, 93 ff., 

98 f . 

Carr-Saunders, cited, 25. 
Carthage, capacity of, 255; culture 

of, 357. 
Caspian Sea, climate of fourteenth 

century, 326. 

Cattell, J. McK., cited, 127. 
Cattle, in Africa, 53 f . 
Centers of civilization, 347 ff. 
Central America, archaeological 
work in, 9; disease in, 12; mis- 
sionary in, 75; morality in, 75; 
negroes in, 67; status of, 298, 
storms in, 367. 
Central Asia, climate of, 7 f ., 390 f . ; 

migrations in, 25. 
Ceylon, ruins in, 366. 
Chaco Canyon, 338. 
Chad, Lake, 327. 
Changes of climate, see Climatic 

Changes of temperature, 138 ff., 140 

ff., 188 ff., 196 f., 222. 
Character, of Europeans in tropics, 

68; relation to climate, 404. 
Character of Races, 7, 23, 29. 
Chemical pollution, of atmosphere, 


Cherokees, 875. 

Chicago, climate of, 402; death rate 
in, 178; storminess at, 215; wind 
at, 204. 

Children, British, in India, 58; gain 
in weight of, 158 f.; in Australia, 



377, 388; in Denver, 137; in 
tropics, 60, 378 ff . ; malaria among, 
393; mental tests of, 31, 103; rude- 
ness in America, 404; selection of, 
24; weather and, 199 ff. 

Chile, climate of, 221 ; death rate of, 

China, capacity of, 255; civilization 
in, 261, 357; climatic advantages, 
404; climatic energy in, 238; early 
greatness of, 354; famines in, 11; 
influence of United States, 350; 
journey to, 11; migrations in, 25; 
past climate of, 15 f.; storminess 
in, 362 f. 

Chinese Turkestan, autumn in, 226; 
climatic energy in, 231 ; expedition 
to, 7; forests in, 317. 

Chlorine, in lakes, 323 f . 

Churchill, W., cited, 53. 

Cigar making, 32; and day of week, 
125; and seasons, 93 Iff., 99 f.; and 
temperature, 162. 

Cincinnati, deaths in, 208. 

Circulation of blood, 165 ff. 

Cities, deaths in, 178, 204 ff., 279; 
influenza in, 189 ff. 

Civilization, agriculture and, 373; 
barometric changes and, 13; cen- 
ters of, 347 ff.; climate and, 12, 
313 f., 387 ff.; conditions of, 291 
ff., 387 ff.; definition of, 242, 255; 
distribution of, 240 ff., 352 ff.; 
higher vs. lower, 67 ff.; in United 
States, 288; map of, 15, 277, 294 f., 
415 ff.; race and, 258 f.; storminess 
and, 12 f.; table of relative, 417. 

Classification of countries, 248. 

Clay, A. T., cited, 842 f., 389. 

Cleveland, deaths in, 208, 213; in- 
fluenza at, 187, 190. 

Climate, of Bahamas, 47; of Central 
Asia, 390 f.; character of ancient, 
400 ff.; civilization and, 2, 12, 813 

f.; in Denmark, 96; and deaths, 
20 f.; energy and, 302, 312; and 
farm efficiency, 41; of Florida, 50 
f.; of ancient Greece, 22 ff.; and 
health, 3; ideal, 220 ff.; vs. inherit- 
ance, 30 ff., 312; of Japan, 95 f.; 
magnitude of effects, 149 ff.; and 
mental activity, 51; methods of 
overcoming, 406 ff.; migrations 
and, 25; of New York, 95 f.; op- 
timum, 6, 15, 20, 161; at Panama, 
67; physiological effects of, 77 ff.; 
psychological effects of, 77 ff.; 
and slavery, 41; of South Africa, 
45; summary of effect of, 10, 11, 
14, 52 f.; uniformity of, 18 f., 338 
f.; vs. weather, 136. 

Climatic changes, in Asia, 8 ; in Cali- 
fornia, 8; diverse views of, 5 f.; 
economic effects of, 387; evidence 
of, 17 f., 316, 339; in Greece, 26 f.; 
growth of idea, 335; and history, 
18, 333; migrations and, 11; nature 
of, 10, 326 ff., 333 f., 335, 340; and 
political disturbances, 11. 

Climatic energy, ancient distribution 
of, 359 ff.; and influenza, 188 ff., 
191; distribution of, 276, 278, 291 
ff., 294 f., 347 ff.; map of, 228 ff. 

Climatic Factor, 8. 

Climatic hypothesis of civilization, 
364 f., 387 ff., 403 ff. 

Climatic pulsations, 7 ff.; glacial 
epochs and, 319 f. 

Climatic zones, shifting of, 315 ff., 
327 f . 

Climographs, 161, 182 ff. 

Cloudiness, effect of, 79, 145, 149 f. 

Coal, relation to manufacturing, 
289 f . 

Coca, in Peru, 368. 

Cold, resistance to, 396. 

Cold Spring Harbor, 194. 

Coldward Course of Progress, 17. 



Colombia, status of, 298. 

Colon, death rate of, 62. 

Colonization, in tropics, 236. 

Colorado, storminess in, 398. 

Color line, 32 ff. 

Columbia, effect of seasons in, 93 ff., 

97; mental tests at, 31. 
Columbus, O., deaths in, 213; in- 
fluenza in, 190. 
Comfort, and atmospheric pollution, 

169 ff.; and temperature, 167. 
Conception, seasonal variations, 

159 f. 

Congo, climate of, 223, 231. 
Connecticut, death rate of, 64, 66; 
effect of changes of temperature 
in, 140 ff., 144; effect of humidity 
in, 112; effect of light in, 109 f.; 
effect of seasons in, 84, 92 ff., 154 
f.; effect of temperature in, 115 ff., 
162; efficiency in, 94 f.; eminence 
in, 306, 308; piece-workers in, 80 
ff.; rank in progress, 289. 
Consumption, selective action of, 

Contagious diseases, and humidity, 

Contributors, to map of civilization, 

256, 415 ff. 

Cooling of houses, 409. 
Copenhagen, children in, 96; test of 

strength at, 128. 
Correlation coefficients, 187 ff., 195 

ff., 289. 
Cotton factories, effect of seasons in, 

93 ff., 97 f., 290. 
Countries, relative civilization of, 

415 ff. 

"Crackers," 42, 52, 311. 
Crampton index, 165 ff. 
Criticisms, of climatic hypothesis, 

366 ff. 

Critics of pulsatory hypothesis, 
355 ff. 

Cross-breeding, 53 f. 

Cuba, civilization in, 266; negroes 
in, 32. 

Cubans, as cigar-makers, 99; effect 
of temperature on, 162; and holi- 
days, 125; optimum temperature 
of, 164. 

Cultivation, as factor in civilization, 

Culture, and civilization, 1, 387; and 
climate, 16 f., 395; test of, 281. 

Cuneiform writing, 353. 

Curve of climate, 319. 

Cuzco, climate of, 368. 

Cycles of climate, 320. 

Cyclonic storms, civilization and, 12 
f.; and climatic changes, 10, 334; 
cycle of, 352; effect of, 136 f.; 
location of ideal, 222 ff. 

Cyprus, forests in, 341. 

Daily wages, at New Britain, 122. 

Dakotas, climate of, 222, 224; edu- 
cation in, 285, eminence in, 311. 

Dark Ages, 11; religion in, 389 f.; 
temperature in, 397. 

Davis, W. M., cited, 7. 

Death rate, in Australia, 376 ff., 381 
ff.; in cities, 279; and climate, 20 
f.; comparative, 62 ff.; in Con- 
necticut, 154; in Europe, 291 ff.; 
and humidity, 177 ff.; and influ- 
enza, 188 ff.; in Japan, 95, 159 f.; 
of miners, 279; in New York, 94 f.; 
after operations, 179 ff.; in Penn- 
sylvania, 154; from pneumonia, 
175 f.; and seasons, 92 ff., 159 f.; 
selective, 62; and temperature, 
162; in tropics, 378; and weather, 

Death Valley, climatic energy hi, 

Deforestation, hypothesis of, 316 f. 



De Geer, S., cited, 320, 339. 

Delaware, eminence in, 806. 

Denmark, climate of, 96; death rate, 
376; seasonal effect on children, 
92, 96. 

Density of population, and influenza, 
188 ff. 

Denver, children in, 137; deaths in, 

"Desert bay," 342 f. 

Desert Botanical Laboratory, 8. 

Deserts, ancient, 400; drought in, 
388; shifting of, 327 f. 

Detroit, deaths in, 213. 

Dexter, O. E., cited, 13, 137. 

Diet, in Bahamas, 47. 

Disease, and aridity, 391; relation 
to atmosphere, 168; and civiliza- 
tion, 60; among Mayas, 331; se- 
lective action of, 391. 

Dixon, R. F., cited, 369. 

Dog, among Indians, 373. 

Domestic animals, and civilization, 
373 ff. 

Dorians, migrations of, 23 f . 

Douglass, A. E., cited, 320, 338. 

Drought, in Palestine, 387 f. See also 

Drunkenness, in Central America, 
71 f. 

Dryness, effect of, 113, 181 f. 

Dublin, L. I., cited, 194. 

Dynamometer, tests with, 78, 128. 

Earnings, of whites vs. colored, 32, 

Economic effects of climatic changes, 

387 ff. 
Economists, and climatic changes, 


Ecuador, temperature of, 227. 
Education, as test of progress, 282; 

and vitality, 275 ff. 

Efficiency, relation to deaths, 154; 
seasonal, 85 ff.; and temperature, 
431 f. 

Egypt, Alexandrian period in, 397; 
ancient climate of, 15, 16, 363 f., 
400; capacity of, 255; character 
in, 30 ff.; civilization in, 297, 357; 
decay of, 13; disease in, 12; effect 
of climate, 51 f.; energy in, 13; 
Greeks in, 27; rainfall in, 398; 
storminess in, 362. 

Egyptians, ancient culture of, 354, 

Einfluss von Klima, 14. 

Electrical apparatus, 102. 

Eminence, distribution in United 
States, 304 ff. 

Energy, and climate, 312; and emi- 
nence, 305 ff.; and health, 154; 
importance of, 302; map of, 234. 

England, climate of fourteenth cen- 
tury, 326; climatic advantages, 220 
f., 224, 226, 404; coal in, 289; death 
rate, 376; rank in civilization, 257. 

English, birth rate in Australia, 382 
ff. ; seasonal marks in, 104 ff. 

Environment, social vs. physical, 
57 f. 

Equatorville, climatic energy at, 231. 

Eskimos, character of, 235. 

Eugenists, 310. 

Euphrates region, ancient climate 
of, 343 ff. 

Euphrates River, 342 f . 

Eurasia, effect on storms, 361 ff. 

Europe, civilization in, 255, 257 ff., 
357; climate of, 221, 223 f.; coal 
in, 289; death rate, 376; impor- 
tance of, 347 ff.; maps of, 291 ff.; 
nervous disorders in, 156. 

Europeans, capacity of, 255; effect 
of tropics on, 56 ff., 68. 

Evolution of Climate, 8. 

Exiles, in Siberia, 287. 



Expansion of Races, 25. 
"Explorations in Turkestan, 7. 

Factories, piece-workers in, 80 ff.; 
seasonal variations in, 92 ff., 407. 

Falkland Islands, climate of, 224. 

Famines, in China, 11, 319. 

Farmers, white vs. negro, 37 ff. 

Fatigue, of nerves, 157. 

Ferrell, J. A., cited, 47. 

Fertile crescent, 342 f. 

Fevers, in Central America, 328 ff. 

Finland, progress of, 260, 397. 

Floods, in France, 325. 

Florida, changes of temperature in, 
140 ff., 143 f.; climate of, 50 f., 
220, 223 f.; factory operatives in, 
14 f.; manufacturing in, 290. 

Fontein, climate of, 367. 

Food, as factor in civilization, 2. 

Foreign born, influenza and, 188 ff. 

Forests, cutting of, 316 f.; in Cy- 
prus, 341; in Mesopotamia, 844; 
and primitive agriculture, 372 ff.; 
and primitive civilization, 374 ff. 

Fourteenth century, climatic stress 
of, 325 f. 

Fraas, O., cited, 13. 

France, climatic advantages, 224, 
404; climographs of, 182; death 
rate in, 20 f., 178; floods in, 325; 
index of civilization, 252; tem- 
perature of, 130, 162. 

French, in World War, 274. 

Fresno, climate of, 221. 

Gale, H. S., cited, 323 f. 

Garden of Eden, 344. 

Gamier, cited, 156. 

Gautama, 255, 355. 

Genius, geographical distribution of, 

Geographers, Association of, 18. 

Geographers, opinions of, 17 f., 19, 


Geologists, and climatic changes, 
17 f. 

Oeopsychische Erscheinungen, 14. 
Georgia, 253; Black Belt of, 812; 
climate, 50; eminence in, 807; high 
school graduates, 283; school at- 
tendance in, 282; seasons in, 97 
f.; storminess in, 398; teachers' 
salaries, 283. 

Germans, birth rate in Australia, 
383 ff.; in World War, 274. 

Germany, ancient climate of, 863 f.; 
civilization in, 252, 267; climatic 
advantages of, 224, 226, 404; cold 
winters in, 326; migrations from, 

GilFillan, S. C., cited, 17, 395, 397. 

Girls, in Bahamas, 50; and bonus, 
89 f.; factory work of, 97; pro- 
portion in Australia, 380; in 
school, 283 f.; sensitiveness to 
climate, 126; and weather, 92 ff., 
139 ff., 141 f. 

Glacial epochs, number of, 338. 

Gouldsbury, cited, 73. 

Government, and progress, 301. 

Grand Rapids, influenza in, 189 f. 

Grasslands, and primitive agricul- 
ture, 372 ff. 

Great Britain, index of civilization, 
252; influence of, 297. 

Great Lakes, climate of, 223; 
storminess on, 230. 

Great Plains, education in, 285. 

Great Salt Lake, 327. 

Greece, ancient climate of, 16, 22 ff., 
363 f.; civilization in, 367; climate 
of, 223, 402; culture of, 357; de- 
cay of, 13; disease in, 12; malaria 
in, 392 f.; natural selection in, 
23 f., 26; in World War, 274. 



Greek Christianity, and progress, 

Greeks, capacity of, 255; in Egypt, 

397; energy of, 13. 
Greenburg, D., cited, 176, 203. 
Gregory, H. E., cited, 78. 
Gregory, J. W., cited, 9, 339 ff. 
Grenfell, W. T., cited, 235. 
Growth, and atmospheric pollution, 

170; and influenza, 188 if. 
Guatemala, drunkenness in, 71; 

past climate of, 16; ruins in, 9, 

328 ff. 

Guinea pigs, and vitiated air, 170. 
Gulf of Lions, storminess of, 362. 

Hampton Institute, 35. 

Hann, J., cited, 229, 368. 

Harper, R. M., cited, 312. 

Harris, J. A., cited, 194. 

Health, and atmosphere, 153 ff.; in 
Australia, 381; and climate, 10 
ff.; and energy, 164; map of, 291 
ff.; and national decline, 27; and 
weather, 194 ff., 277. 

Health resorts, climate of, 162. 

Hearn, Lafcadio, cited, 54 f. 

Heart, relation to influenza, 188 ff. 

Heart diseases and influenza, 191. 

Heart-rate, 165 ff. 

Heat, effect of, 126 f., 171; effect 
on death rate, 117; protection 
against, 396. 

Heating and Ventilating Engineers, 

Hebrides, climate of, 221. 

Hebron, 333; hospital at, 388. 

Hellpach, cited, 14, 73, 148. 

Herbette, cited, 337. 

Heredity, and eminence, 307; op- 
portunity vs., 312. 

Hermans, cited, 165. 

Hess, A. F., cited, 167. 

Hieroglyphs, 352. 

Highlands, effect on storms, 860. 

High School, graduates of, 282 f. 

Hill, L., cited, 166. 

Himalayas, storminess in, 362. 

Hindu, capacity of, 255. 

Hinges, work with, 82. 

Historians, and climatic changes, 
18, 241 ff. 

History, basis of, 369 f.; and cli- 
matic changes, 18, 333. 

Hittites, 356. 

Holidays, and Cubans, 125. 

Holland, storms in, 325. 

Honore, M. F. C., cited, 53. 

Hookworm, 60; in Bahamas, 47. 

Horse, metaphor of, 152, 161, 225, 

Horse-races, in United States, 78. 

Hospitals, in Boston, 21; psychia- 
tric, 156. 

Houses, cooling of, 409; effect of, 
110 f.; heating of, 406. 

Huguenots, 809. 

Human activity, and changes of 
temperature, 140 ff.; and seasons, 
92 ff.; and temperature, 124 ff. 

Human energy, map of, 15, 234. 

Humboldt, cited, 76. 

Humidity, ancient, 401; and carbon 
dioxide, 133 ff.; curves of, 212; 
data for, 233; and death rates, 
177 ff., 196 ff., 202 ff.; effect of, 
14 f., 109 f., 167 f., 209 f., 214, 
219; and health, 204 ff.; ideal, 
222; and influenza, 188 ff.; mag- 
nitude of effect, 149 f.; and op- 
erations, 179 ff.; optimum of, 161; 
optimum for negroes, 164; in 
Paris, 174. 

Hungary, in World War, 274. 

Hunting, and natural selection, 870. 

Iceland, civilization in, 270, 801; 
progress in, 299, 897. 



Idaho, education in, 286; eminence 
in, 311; school attendance in, 282. 

Illinois, education in, 285; eminence 
in, 308; teachers' salaries, 283. 

Illiteracy, as test of progress, 282. 

Immigration, racial character and, 
309 f. 

Immorality, in tropics, 73. 

Incas, 329. 

Index of civilization, 250. 

India, ancient climate of, 363; 
British in, 68; capacity of, 255; 
Christianity in, 301; civilization 
in, 357; deaths and weather in, 
181; early greatness of, 354 f.; 
European domination in, 296; 
growth of population, 58; hill 
tribes of, 300; humidity data for, 
233; influenza in, 191; and Japan, 
351; Moguls in, 391; past climate 
of, 15 f.; storminess in, 362. 

Indiana, eminence in, 308. 

Indianapolis, deaths and tempera- 
ture in, 213. 

Indians, contact with whites, 56; 
energy of, 369 ff.; inheritance of, 
309, 370; in South America, 57. 

Indo-China, disease in, 12; early 
greatness of, 354; European domi- 
nation in, 296; ruins in, 866; 
storms in, 367. 

Industry, tropical, 68 ff. 

Infanticide, in Attica, 24. 

Infants, blood of, 157; death rate 
in Australia, 378. 

Infection, and atmospheric pollu- 
tion, 169 ff. 

Influenza, and humidity, 178; and 
weather, 21, 187 ff. 

Infusoria, temperature relations of, 

Inheritance, as factor in civilization, 
1 ; and climate, 3, 80 ff . ; and emi- 
nence, 305 ff.; North vs. South, 

42; vs. opportunity, 312; of Peru- 
vians, 368. 

Insanity, in California, 225; in Lon- 
don, 156; in tropics, 227. 

Insurance companies, data of, 278. 

Intermarriage, among Greeks, 24. 

International Institute of Statistics, 
63 f. 

Inventions, for resistance to cold, 

lonians, migrations of, 23 f. 

Iowa, eminence in, 308; immigrants 
to, 309. 

Ireland, changes of climate in, 319; 
climatic advantages, 221, 231, 404; 
rank in civilization, 258. 

Irish, birth rate in Australia, 383 
ff.; migration to America, 25. 

Iron, and Indians, 371 ff.; and 
manufacturing, 289 f. 

Iroquois Indians, 369. 

Islam, rise of, 9. 

Ispahan, rainfall at, 400. 

Italians, in factories, 82 f. 

Italy, civilization in, 252, 357; cli- 
mate of, 223 f.; climographs of, 
182; deaths in, 20 f.; humidity in, 
178; malaria in, 892 f.; optimum 
temperature in, 163; sexual ir- 
regularities in, 74; storminess in, 
361; temperature in, 162; in 
World War, 274. 

Jacksonville, carpenters in, 98 f.; 
cigar-makers in, 99; hospitals in, 
156; manufacturing in, 290; sea- 
sons in, 93 ff.; whites vs. negroes, 

Jamaica, negroes in, 57. 

James, W. B., cited, 145. 

Japan, civilization in, 201, 357; cli- 
mate of, 224; climatic energy in, 
239; death rate in, 95; importance 
of, 350 f.; index of civilization, 



252; manufacturing in, 290; races 
of, 253; storminess in, 361 ff. 

Java, disease in, 12; growth of 
population, 58; ruins of, 366. 

Jefferson, M., cited, 281. 

Jenghis Khan, 391. 

Jewish atrocities, 260. 

Jews, capacity of, 255; early cul- 
ture of, 356. 

Johannesburg, deaths and weather 
in, 181. 

Johnson, D. W., cited, 345. 

Jones, W. H. S., cited, 12, 393 f. 

Kansas, climate of, 224; rank in 

progress, 288. 

Kentucky, eminence in, 311. 
Khabur River, 343. 
Khartum, climatic energy at, 231. 
Kropotkin, cited, 7, 11. 
Kullmer, C. J., cited, 13, 230, 398. 

Labrador, influenza in, 190. 

Lag, of health after weather, 161. 

Lakes, chlorine in, 323 f.; saline, 
323, 327; sodium in, 323 f. 

Latin America, Christianity in, 301; 
whites in, 58. 

Latitude, and influenza, 188 ff. 

Leadership, among whites vs. ne- 
groes, 35. 

Legrain, cited, 843. 

Lehmann, cited, 13, 78, 96, 103, 128, 

Letters about map of civilization, 
242 ff.; as test of progress, 281. 

Life insurance, in South, 279; sta- 
tistics, 276. 

Light, effect of, 109 f. 

Lincolnshire, storms in, 325. 

Liverpool, climate, 221. 

Liverpool School of Tropical Medi- 
cine, 893. 

Livingstone, D., cited, 73. 

London, climate of, 220; efficiency 
in, 229; insanity in, 155; mur- 
ders in, 404. 

Longitude, and influenza, 188 ff. 

Lop Nor, climate of fourteenth cen- 
tury, 326. 

Lorain, cited, 32. 

Los Angeles, climate of, 164, 221; 
influenza in, 189; suicides in, 225; 
water supply of, 323 f. 

Louisiana, school attendance in, 282 

Loyalists, in Bahamas vs. Canada, 

Lucknow, deaths and weather in, 

Lumber industry, in Bahamas, 34. 

Lumber trade, of Mediterranean, 

MacDougal, D. T., cited, 8, 129. 
Madras, deaths and weather in, 181. 
Madrid, deaths and weather in, 181. 
Magazines, and climate, 51. 
Maine, eminence in, 306, 311; kigh 

school graduates in, 283. 
Malaria, 12. 
Malaria, in Bahamas, 47; in Central 

America, 328 ff.; changes in, 12; 

climate and, 22; in Greece, 26; 

selective action of, 391 ff.; tropi- 
cal, 60. 

Male death rate, in Australia, 878. 
Manchester, tests of carbon dioxide 

in, 133. 
Manufacturing, and influenza, 188 

ff.; and progress, 281, 289. 
Map, of civilization, 240, 256 ff., 

415 ff.; of climate vs. eminence, 

812 f.; of climatic energy, 228 if., 

232 ff. 
Mari, 842 f . 

Maritime provinces, climate of, 224. 
Mark Twain, cited, 136. 
Marriage, 810. 



Maryland, boys in school, 283 ff.; 
climate of, 223 f,; school atten- 
dance in, 282. 

Massachusetts, advantages of, 313; 
death rate in, 117; eminence in, 
303, 306, 308; hospitals in, 156; 
rank in progress, 288; railroads 
in, 281; school attendance in, 283; 
teachers' salaries, 283. 

Massaua, efficiency in, 229. 

Mathematics, seasonal marks in, 
104 ff. 

Maya history, tree growth and, 332. 

Maya regions, past climate of, 16. 

Maya ruins, 9, 329. 

Mayas, architecture of, 329 ff.; cal- 
endar, 329; capacity of, 255; 
civilization of, 359; climate, 362; 
sculpture, 329 ff. 

Mayo, cited, 32. 

McHattie, Dr., cited, 47. 

Mecca railroad, 388. 

Medes, 353. 

Medical practice, and influenza, 
188 ff. 

Mediterranean region, early culture 
of, 357; vegetation of, 9 f. 

Melon, and wind, 138. 

Memphis, storminess at, 217; 
weather and deaths in, 208, 213. 

Men, distribution in Australia, 380; 
effect of weather on, 141 f.; op- 
timum temperature for, 130; in 
tropics, 378 ff. 

Mental activity, and climate, 51; 
and seasons, 103 ff . ; and tempera- 
ture, 128 f. 

Mental disorders, seasons and, 156 f. 

Mental efficiency, and atmospheric 
pollution, 169 ff.; and tempera- 
ture, 167. 

Mental tests, white vs. colored, 31. 

Mental work, changes of tempera- 
ture and, 142 f.; and climate, 103 

ff.; optimum temperature for, 168. 

Mesopotamia, ancient climate of, 
343 f., 363 f., 400; capacity of, 
255; civilization in, 352 f., 357; 
early greatness of, 355 f.; migra- 
tions in, 407 f.; ruins in, 889; 
storminess in, 362. 

Metabolism, and temperature, 134, 

Metropolitan Life Insurance Com- 
pany, 194. 

Mexicans, inheritance of, 309. 

Mexico, civilization in, 266; climate 
of, 223, 408; deaths and weather 
in, 181; drunkenness in, 71; index 
of civilization, 252; status of, 298. 

Mexico City, deaths and weather in, 

Micro-organisms, see Bacteria. 

Middle Atlantic states, agriculture 
in, 40. 

Migrations, aridity and, 390; from 
Bahamas, 46 f.; and climate, 3, 
25; and drought, 388; effect in 
tropics, 59; into Greece, 23 f., 27; 
of Indians, 370; and natural se- 
lection, 52 f.; nature of, 26; 
seasonal, 407 ff.; weekly, 409 f. 

Milan, death rate and weather in, 
182; weather in, 103. 

Milwaukee, influenza in, 187. 

Mind, effect of tropics on, 69. 

Miners, death rate of, 279. 

Ministers, in Bahamas, 49. 

Minneapolis, weather and deaths in, 
182, 208. 

Minnesota, death rate of, 63. 

Minoans, 23. 

Missionaries, in Central America, 
75; in China, 350; in tropics, 73; 
in Turkey, 74, 350. 

Mississippi, education in, 287; 
school attendance in, 288; 
teachers' salaries, 283. 



Moab, drought in, 387 f. 

Moguls, in India, 391. 

Mohammed, aridity and teachings 
of, 390. 

Mohammedanism, and progress, 301. 

Moisture, effect on health, 174 ff. 
See also Humidity. 

Monotony, of tropical climate, 227. 

Montana, boys in school, 285; edu- 
cation in, 286; eminence in, 311. 

Montesquieu, cited, 3, 76. 

Moorhead, cited, 369. 

Morality, in Central America, 75. 

Mormonism, education and, 286. 

Morse, cited, 31. 

Mortality, in Europe, 291 ff.; and 
weather, 174 ff. 

Mosquito, anopheles, 392. 

Mountain sheep, 374. 

Mucous membranes, effect of tem- 
perature on, 168. 

Murders, in Boston, 404; in London, 

Mutations, and climate, 3. 

Naivasha, stock at, 53. 

Nansen, F., cited, 237. 

Nantucket, climate of, 161. 

Naples, deaths and weather in, 182. 

Nasal mucosa, temperature and, 

Nashville, weather and deaths in, 
208, 213. 

National Research Council, 187, 194. 

Natural selection, 52 f., 365 ff.; 
aridity and, 394; climate and, 6 
f.; death rate and, 379 ff.; in 
Greece, 21 ff., 26; among Indians, 
370; among Mayas, 331; in Meso- 
potamia, 352; in Peru, 368; in 
tropics, 385. 

Nearing, S., cited, 302 ff. 

Nebraska, eminence in, 306, 808. 

Neglected Factor in Race Develop- 
ment, 25. 

Negroes, among cigar-makers, 99; 
education and, 287; efficiency of, 
57; humidity and death rate 
among, 178; influenza and, 188 ff.; 
mentality of, 31; optimum for, 
21, 164; vs. Teutons, 30 ff.; in 
United States, 395. 

Nephritis, and influenza, 188 ff. 

Nerves, fatigue of, 157; in Peru, 
368; and wind, 137 f. 

Nervous disorders, in California, 
225; in Europe, 156. 

Nervousness, origin of, 115. 

Netherlands, index of civilization, 

Neurasthenia, selective action of, 

Nevada, education in, 286; eminence 
in, 311; railroads in, 281; rank in 
progress, 289. 

Newark, pneumonia in, 177. 

New Britain, changes of tempera- 
ture in, 139 ff.; factory operatives 
in, 14 f., 80 ff.; wages in, 122. 

New England, climate, 224; educa- 
tion, 285; eminence in, 303, 306, 
308; inheritance in, 42; loss of 
ability, 310; manufacturing in, 
290; weather of, 146. 

Newfoundland, civilization of, 267. 

New Hampshire, high school gradu- 
ates, 283; eminence in, 306, 311. 

New Haven, changes of tempera- 
ture in, 139 ff.; factory operatives 
in, 14 f., 80 ff.; influenza in, 190; 
weather and deaths in, 205 f., 208. 

New Jersey, rank in progress, 289; 
school attendance in, 283; 
teachers' salaries, 283. 

New Mexico, education in, 285 ff.; 
eminence in, 308; rank in prog- 
ress, 288. 



New Orleans, climate of, 161; in- 
fluenza in, 189 f. 

Newport, climate of, 402. 

New South Wales, birth rate among 
natives of, 383 ff.; death rate, 
381 ff. 

New York, climate of, 220, 402; 
death rate of, 63 f., 248; deaths 
from pneumonia, 175 f.; educa- 
tion in, 285; eminence in, 306; 
hospitals in, 156; humidity and 
deaths in, 178, 214; influenza in, 
185 f., 189; negroes in, 32; pneu- 
monia in, 177, 208; rank in prog- 
ress, 289; seasons in, 92 ff.; 
storminess in, 215, 334; tempera- 
ture variations, 183 ff. ; weather 
and deaths in, 194 ff., 205 f., 208. 

New York Life Insurance Company, 

New York State Ventilation Com- 
mission, 100, 127, 165, 177, 181, 
202, 214. 

New Zealand, climate, 221, 224; 
death rate of, 64, 376; importance 
of, 351. 

Norbury, F. P., cited, 156. 

Norse, in Greece, 23. 

North, changes of temperature in, 
144; slavery in, 41; vs. South, 36 
ff., 403 f . 

North Africa, climate of, 223; in 
Dark Ages, 397. 

North America, civilization in, 263; 
climate of, 223. 

North Carolina, eminence in, 307, 
311; seasons in, 97. 

Norway, progress of, 396. 

Nova Scotia, ability in, 267 f. 

Ohio, eminence in, 308; rank in 
progress, 289; teachers' salaries, 

Old Testament, 344. 

Operations, weather and, 21, 179 ff. 
Opportunity, eminence and, 305 ff., 

311; heredity vs., 312. 
Optimum climate, 161. 
Optimum temperature, 126 ff., 163. 
Oregon, eminence in, 306, 308; high 

school graduates, 382; rank in 

progress, 289; teachers' salaries, 


Ostiaks, character of, 235. 
Overheating, 171. 
Owens Lake, 321; salt in, 323 ff. 
Oxygen, absorption by blood, 78; 

consumption by crayfish, 132. 

Pacific coast, climate, 221, 223; edu- 
cation on, 285; manufacturing on, 

Palestine, climatic changes in, 389; 
capacity of, 255; drought in, 887; 
palm and vine in, 339 f.; popula- 
tion of, 389; storminess in, 362; 
tree growth and, 332 f.; vegeta- 
tion of, 9 f . 

Palestine and Its Transformation, 
8, 28. 

Palm, climate and, 9 f., 339 f. 

Panama, death rate of, 62 f.; health 
in, 61 ff.; malaria in, 329, 392. 

Parable, of savages, 405. 

Paraguay, index of civilization, 252. 

Paralysis, in Paris, 156. 

Paramoecium, temperature and, 180. 

Parasites, and civilization, 2. 

Paris, climate of, 220, 402; paraly- 
sis in, 156; humidity in, 174. 

Parsis, progress among, 300. 

Partial correlations, 187, 195 ff. 

Patagonia, climate of, 221. 

Patterson, Dr., cited, 888. 

Pearl, R., cited, 187. 

Pedersen, cited, 13, 78, 96, 103, 128, 

Peking, climate of, 220. 



Pellagra, 60. 

Penck, A., cited, 10, 326. 

Pennsylvania, education in, 285; 
eminence in, 308; immigrants to, 
309; piece-workers in, 102 ff.; 
seasons in, 154 f. 

Peonage, 59. 

Persia, 355; ancient climate of, 400; 
early greatness of, 354, 357; 
palms in, 340; storminess in, 362; 
wind in, 138 f. 

Persians, in Mesopotamia, 353. 

Peru, climate of, 368; civilization in, 
357; ruins of, 367; status of, 298. 

Peten, malaria in, 327. 

Pfeffer, cited, 129. 

Philadelphia, influenza in, 187; 
weather and deaths in, 208. 

Phoenicia, ancient climate of, 299. 

Phoenicians, early culture of, 356. 

Phosphates, in blood, 157. 

Physical activity, vs. mental, 105 f ., 

Physical work, and atmosphere, 168, 
170; and change of temperature, 
142 f. 

Physicians, busy season of, 153 f. 

Physiological reactions, and atmos- 
pheric pollution, 169 ff. 

Physiology, aridity and, 391. 

Piece-work, and temperature, 162. 

Piece-workers, day of week and, 
122; in New England, 80 ff. 

Pilgrims, 309. 

Pittsburgh, factory operatives in, 
14 f., 102 ff.; seasons in, 84; tem- 
perature in, 162; weather and 
deaths in, 208, 213. 

Place, vs. race, 30 ff. 

Plants, temperature and, 128 f.; 
variability and, 145. 

Pneumonia, deaths from, 20 f., 175 
f.; variability and, 183 f.; weather 
and death rate from, 178. 

Poles, in World War, 274. 
Political corruption, and national 

decline, 27. 

Poor whites, 42, 52, 97, 811; in Ba- 
hamas, 33. 
Population, decline in, 389; early 

density of, 337; of Japan, 160; in 

tropics, 58. 

Population Problem, 25. 
Porter, W. T., cited, 158. 
Portland, Ore., climate of, 161. 
Port Said, rainfall at, 400. 
Portuguese, in World War, 274. 
Potatoes, in Ireland, 25. 
Practice, effects of, 86. 
"Premium" plan, 89. 
Presbyterian Hospital, at Hebron, 


Probable error, 197 f. 
Professional men, climate and, 385. 
Progress, map of, 291 ff.; railroads 

as test of, 281. 
Progressive desiccation, hypothesis 

of, 316 f. 

Protestantism, and progress, 301. 
Providence, pneumonia in, 177. 
Provinces, rank of Canadian, 429 f. 
Psychiatric hospitals, 156. 
Psychological vs. physical effects of 

weather, 148. 

Pulsations of climate, 17, 338 f. 
Pulsatory hypothesis, 7, 315 ff., 

335 ff. 

Pulse of Asia, 7, 28. 
Pumpelly, Raphael, 7. 
Pumpelly Expedition, 7. 
Puritans, 308 f.; slaves among, 41. 
Putter, cited, 134. 

Quakers, 309. 

Queensland, climate of, 384; death 

rate, 376, 378, 381 ff. 
"Queensland walk," 885. 
Queenslanders, birth rate among, 



383 ff.; in World War, 377. 
Quintana Roo, malaria in, 329. 
Quito, relative efficiency in, 229; 

temperature at, 227. 

Rabbits, and temperature, 168. 

Race, and civilization, 258 f.; maps 
of, 300 f.; vs. place, 30 ff.; vs. 
territory, 254. 

Races, and aridity, 394 f.; and in- 
fluenza, 188 ff.; capacity of, 296. 

Racial character, and immigration, 
309 f. 

Racial inheritance, and civilization, 
27,387; in Greece, 21 ff. 

Racial mixture, and climate, 3. 

Racial selection, and climate, 6 f. 

Railroads, as test of progress, 281. 

Rain, ancient, 400 f.; and climatic 
changes, 9 f.; in Egypt, 398; and 
rate of work, 98 f.; relation to 
storminess, 398 ff.; in Turkey, 79. 

Range of temperature, ideal, 222. 

Ratzel, cited, 76. 

Reclus, cited, 7. 

Rectal temperature, 165 ff. 

Red corpuscles, altitude and, 78. 

Relative humidity, see Humidity. 

Religion, among Arabs, 390; in 
Dark Ages, 390; and progress, 

Reproduction, in paramoecia, 131. 

Respiration, rate of, 166 ff. 

Respiratory diseases, ideal climate 
for, 176; and moisture, 174 ff. 

Rhode Island, eminence in, 308; 
railroads in, 281. 

Rhodes, early culture of, 367. 

Rhodesia, backwardness in, 73; cli- 
mate of, 367; ruins of, 367. 

Richmond, children in, 63; influenza 
in, 190. 

Rickets, seasonal course of, 157. 

Rirers, freezing of, 325 f. 

Riviera, climate of, 220. 
Rochester, deaths and temperature 

in, 213. 

Rockefeller Health Commission, 47. 
Rocky Mountain states, education 

in, 285. 

Rodishev, cited, 238. 
Roman Catholicism, and progress, 

Romance nations, civilization of, 

258 f. 

Romans, capacity of, 255. 
Rome, decline of, 397; disease in, 

12; malaria in, 392 f. 
Ross, Sir Ronald, cited, 393 f. 
Ruins, in Central America, 328 ff. 
Russia, climatic advantages, 404; 

humidity data for, 233; possible 

migrations in, 407 f. 
Russians, in World War, 274. 

Sabseans, 354. 

Sacramento, suicides in, 225. 

Saint Louis, weather and deaths in, 
178, 208. 

Saint Paul, capacity of, 255; in- 
fluenza in, 189 f.; weather and 
deaths in, 182, 208. 

Salines, in lakes, 323. 

Sand dunes, 327. 

San Diego, climate of, 221; suicides 
in, 225. 

San Francisco, climate of, 164, 221, 
224 f.; efficiency in, 229; stormi- 
ness in, 334; suicides in, 225; 
weather and deaths in, 178, 182, 

Sanitation, and influenza, 188 ff. 

Sanscrit, 355. 

Saranac Lake, seasons at, 92 ff.; 
tuberculosis at, 94. 

Sayles, R. W., cited, 839. 

Scandinavia, climate of, 224. 



Scandinavians, in United States, 


School children, strength of, 92, 96. 
Schools, attendance at, 282 f.; effect 

on growth, 158; as test of prog- 
ress, 282. 

Scotch, in Australia, 382 ff. 
Scotland, climate of, 222; progress 

of, 396. 

Screws, work with, 82. 
Scythians, 353. 

Seasonal migrations, 407 f., 409 f. 
Seasonal variations in energy and 

health, 154. 
Seasons, ancient, 400; and children's 

weight, 158 f.; effect of, 76 ff.; 

human activity and, 92 ff.; in 

Japan, 159 f.; rhythms of, 96. 
Seattle, climate of, 161, 221 ; stormi- 

ness in, 215. 

Seistan, 340; wind in, 137 f. 
Selection, in Greece, 27. 
Semites, in Mesopotamia, 352. 
Semple, E. C., cited, 341. 
Sequoia Washingtoniana, 8 f. 
Sequoias, 321. 

Seventh century, dryness of, 390. 
Sex, and influenza, 188 ff.; and 

weather, 139 ff. 
Sexes, proportion in Australia, 380 

ff.; relation of, in tropics, 72 ff. 
Sexual reproduction, 131. 
Sheane, cited, 73. 
Sheep, in Africa, 53 f. 
Shifting, of civilization, 347 ff.; of 

climatic zones, 315 ff., 327 f. 
Siam, status of, 296. 
Siberia, energy in, 236 ff.; humidity 

data for, 233; status of, 296. 
Sirocco, in Italy, 74. 
Slaves, 41; in Bahamas, 47. 
Slavic nations, civilization of, 260. 
Slowness, of tropical people, 70 f. 
Slubbing, 97 f . 

Smoothing, of curves, 86. 

Snow, and palms, 340. 

Social degeneracy, and national de- 
cline, 27. 

Social standards, in tropics, 73 f. 

Sodium, in lakes, 323 f . 

South, books in, 51 ; changes of tem- 
perature in, 144; human capacity 
in, 86 ff.; life insurance in, 279; 
slavery in, 41; teachers' salaries, 

South Africa, climate of, 45; fu- 
ture of, 53; status of, 297; whites 
vs. negroes, 43 ff. 

South America, civilization in, 262, 
298; climate of, 221, 223 f.; horse- 
races in, 78; Indians in, 57; rela- 
tion to Europe, 348. 

South Australians, birth rate 
among, 383 ff. 

South Carolina, advantages of, 313; 
education in, 287; effect of sea- 
sons in, 97 f.; eminence in, 306, 
311; high school graduates in, 
283; school attendance in, 283. 

South Dakota, education in, 286; 
teachers' salaries, 283. 

Southern California, climate of, 224. 

Spain, death rate of, 62; in World 
War, 274. 

Specialists, opinions as to climate, 
339 ff., 345 f. 

Speeding, 97 f. 

Spleen, effect of malaria on, 393. 

Spooling, 97 f. 

Spring fever, 128. 

Standard Oil Company, 350. 

Standard population, 292, 376, 381. 

Standards of civilization, 254. 

States, relative rank of, 429 f. 

Stefansson, V., cited, 395. 

Stevens, cited, 44. 

Stock, P. G., cited, 44. 

Storminess, ancient, 401; changes 



in, 398 ff.; civilization and, 12; 
and climatic changes, 9 f.; distri- 
bution of, 359 ff.; effect of, 214 
ff.; and health, 181 ff., 204 ff., 
219; map of, 858 ff.; optimum, 
161; and rainfall, 398 ff.; shifting 
of, 327 f. 

Storms, and deaths, 214 ff.; correc- 
tion of curves of, 212; and health, 
210; ideal, 223 f.; stimulus of, 
147 f. 

Strands, at Owens Lake, 325. 

Strong, cited, 31. 

Students, marks of, 104 ff. 

Subtropical storm belt, 861 f. 

Suicide, in California, 226. 

Sumer, 352. 

Summer, effect on growth, 158 f.; 
effect on work, 115 ff. 

Sunspots, 361 f. 

Surgical operations, weather and, 
179 f., 186. 

Sweden, cold winters in, 326; manu- 
facturing in, 290; progress of, 

Swedish bath, 146. 

Switzerland, index of civilization, 
252; manufacturing in, 290. 

Syria, ancient climate of, 344 f., 
388 f., 399 f.; civilization in, 357; 
desiccation in, 317; population of, 
389; storminess in, 362. 

Syrians, early culture of, 356. 

Takla-Makan, autumn in, 226. 
Tampa, cigar-makers at, 99; climate 

of, 161; manufacturing in, 290; 

seasons in, 93 ff.; temperature in, 

162; whites vs. colored in, 83; 

work by day of week, 125. 
Tasmanians, birth rate among, 

383 ff. 

Taylor, F. B., cited, 820. 
Teachers, salary of, 283. 

Teheran, rainfall at, 400. 
Temperature, ancient, 400; carbon 
dioxide and, 133 ff.; changing 
adaptation to, 397 ff.; and cli- 
matic changes, 10, 334; correction 
of curves of, 211 f.; and culture, 
17; and daily deaths, 196 ff.; 
effect of, 14 f.; and efficiency, 109 
ff., 115 ff., 431 ff.; effect of high, 
165; of glacial period, 340; and 
health of cities, 204 ff., 208 f., 219; 
and human activity, 124 ff.; ideal, 
220; and influenza, 188 ff.; mag- 
nitude of effect of, 149 f.; and 
mental activity, 107 f.; and opera- 
tions, 179 ff.; optimum, 161; 
range of, 137; and vital processes, 
130 ff. 

Ten Kate, H., cited, 252. 

Tennessee, eminence in, 311. 

Teutonic regions, 258. 

Teutons vs. negroes, 30 ff. 

Texas, rank in education, 287. 

Thomson, cited, 133. 

Thucydides, 24. 

Tibet, 355. 

Tierra del Fuego, climate of, 224. 

Tobacco, 290; and weather, 101. 

Tobacco factories, seasons in, 97. 

Toledo, deaths and temperature in, 
213; influenza in, 189 f. 

Tools, stone vs. iron, 371 f. 

Torrid zone, effect on Europeans, 
56 ff. 

Transportation, and optimum cli- 
mate, 396. 

Tree growth, as measure of climate, 
8, 320, 333. 

Tree rings, in ruins, 338. 

Tropical Australia, disease in, 377 1 

Tropical diseases, 60 ff. 

Tropical inertia, 70. 

Tropical labor, 57. 

Tropical medicine, 67. 



Tropics, adjustment to climate of, 
408; character of Europeans in, 
68; colonization in, 70; death rate 
in, 378; influenza in, 192; insur- 
ance in, 279; natural selection in, 
385; relation to ideal climate, 226; 
white men in, 66 ff., 376 ff. 

Tubercular patients, seasonal effect 
on, 92 ff. 

Tuberculosis, in Adirondacks, 94; 
and influenza, 188 ff., 191. 

Tumors, and influenza, 188 ff. 

Turk, rule of, 9. 

Turkestan, expedition to, 7. 

Turkey, effect of rain in, 79; in- 
fluenza of United States in, 350; 
winds in, 74. 

Typewriting, and temperature, 127. 

Typhoid fever, and influenza, 188 ff. 

Ultra violet light, effect on blood, 

Uniformity, of tropical climate, 227. 

United States, civilization in, 266; 
climate of, 221, 223 f.; climatic 
advantages, 404; climographs of, 
182; coal in, 289; death rate of, 
62 f., 376; deaths vs. climate in, 
20 f.; distribution of civilization 
in, 288; early inhabitants of, 369 
ff.; effect of temperature in, 162; 
humidity data for, 233; humidity 
and death rate in, 178; impor- 
tance of, 348 ff.; index of civiliza- 
tion, 252; influenza in, 21; map of 
civilization in, 277; maps of, 291; 
negroes in, 395; psychiatric hospi- 
tals in, 156; rank of states, 429 f.; 
Scandinavians in, 395; South vs. 
North, 36 ff.; statistics in, 275; 
status of, 297; storminess in, 361; 
vitality and education in, 275 ff. 

United States Commissioner of 
Education, 282. 

United States Military Academy, 
students' records at, 14 f. 

United States Naval Academy, stu- 
dents' records at, 14 f. 

United States Steel Company, 350. 

Utah, boys in school, 283 ff.; edu- 
cation in, 285 f.; eminence in, 311; 
rank of, 289; school attendance 
in, 282. 

Vacations, effect of, 106 f.; effect 
on growth, 158; effect on work, 

Van't Hoff's law, 131 f. 

Variability, effect of, 173; and 
health, 181 ff., 201 ff., 204 ff.; 
ideal, 223; in Italy, 163; magni- 
tude of effect, 149 f.; in New 
York, 183 ff.; optimum, 161; value 
of, 138 ff. 

"Varves," 320. 

Vasotone, 165 ff. 

Vedas, 355. 

Vegetation, and Indian civilization, 
371 ff.; in Mediterranean region, 
9 f. 

Venezuela, status of, 298. 

Ventilation, 170 ff. 

Vera Cruz, climate of, 408. 

Vermont, eminence in, 306, 311. 

Vicksburg, climate of, 402. 

Victoria, birth rate among natives 
of, 383 ff.; death rate, 381 ff. 

Vine, climate and, 9 f. 

Virginia, books in, 51; factory op- 
eratives in, 14 f. 

Vital processes, and temperature, 
130 ff. 

Vitality, in United States, 276, 
278 f . 

Wages, of factory workers, 83 ff.; 
per day of week, 121 ff.; varia- 



tions in, 103; of whites vs. colored, 
32 ff. 

War of Secession, 41. 

Ward, R. DeC., cited, 339. 

Washington, D. C., colored children 
in, 31 f. 

Washington (state), death rate of, 
64; progress in, 289, storminess 
in, 217; teachers' salaries, 283. 

Weather, vs. climate, 136; and 
deaths, 20 ff.; and health, 194 ff., 
277; and influenza, 188 ff., 191; 
numerical expression of, 190; and 
operations, 21; and work, 15, 
136 ff. 

Weather Influences, 13. 

Weavers, work of, 97 f. 

Week, effect of day of, 120 ff. 

Weekly migrations, 409 f. 

Weight, gain of, 94; gain among 
children, 158. 

West, teachers* salaries, 283. 

West Indies, civilization in, 266. 

West Point, students' records at, 
14 f., 104 ff.; changes of tempera- 
ture at, 140 ff. 

West Virginia, education in, 287; 
eminence in, 311. 

Wheat, growth and temperature, 

"White Australia," 377, 384 f. 

Whites, humidity and death rate 
among, 178; mentality of, 31; in 
tropics, 56 ff., 376 ff. 

Who's Who in America, 302, 310. 

Will, weakness of, in tropics, 68. 

Wind, ancient, 401; correction of 
curves of, 212; effects of, 137 f.; 
and health, 204 ff., 210; and re- 
spiratory diseases, 175. 

Wind of One Hundred and Twenty 

Days, 138. 

Winslow, C-E. A., cited, 165. 
Winston-Salem, seasons at, 92 ff. s 97. 
Winters, cold, 326; and growth, 158 

f.; and work, 118 ff. 
Wisconsin, immigrants to, 309. 
Wissler, C., cited, 369. 
Woeikof, cited, 337. 
Women, in Bahamas, 50; birth rate 

in Australia, 378; climate and, 

385; death rate in Australia, 378; 

distribution in Australia, 380; 

dress of, 73 f.; in Japan, 160; 

selection of, 24, 380; in tropics, 

73, 378 ff. 

Woodruff, C. W., cited, 26, 109, 130. 
Work, and weather, 136 ff. 
World, maps of, 294 f . 
World Power and Evolution, 20 f., 

World War, capacity of races in, 

271 ; Queenslanders in, 377. 
Wyoming, boys in school, 285; edu- 
cation in, 285; eminence in, 311. 

Yale Expedition to Palestine, 8. 
Yale University, death rate at, 64, 

66 f.; Nova Scotian students at, 


Yangtse valley, storminess in, 363. 
Yellow fever, changes in, 12. 
Yemen, climate of, 367. 
Yucatan, capacity of, 255; ruins in, 

8, 328 ff., 332. 

Zimbabwe, climate of, 367. 
Zulus, 43; backwardness of, 73.