THE LIFE OF MAN IN THE TROPICS

Climate and Man: General—Some Old Views Regarding the Effects of Climate on Man—Factors in the Problem Other than Climate—Climate and Habitability—The Development of the Tropics—The Labour Problem in the Tropics—The Government of Tropical Possessions—Primitive Civilisation and the Tropics—Dwellings in the Tropics—Clothing in the Tropics—Food in the Tropics—Agriculture, Arts, and Industries in the Tropics—Some Physiological Effects of Tropical Climates—The Equatorial Forests—The Open Grass-Lands of the Tropics: Savannas—Trade Wind Belts on Land: the Deserts—Trade Wind Belts at Sea—Monsoon Districts—Tropical Mountains.

_Climate and Man: General._ Man’s climatic environment affects him in many ways. His clothing, dwellings, food, occupations, and customs; his physical and mental characteristics; his systems of government; his migrations; his history—all are affected to a greater or less degree.

Civilised man protects himself more or less successfully against unfavourable climatic features. Thus, there is a gradual transition from the primitive shelter made of branches of trees, of skins, or leaves, to the permanent and highly elaborate modern building, which is both heated and cooled artificially. The building materials; the methods of uniting these materials, as by braiding, or binding, or by the use of mortar, usually show the control of climate. Moreover, the material often determines the general plan of the building. There is also the transition from the primitive and scanty clothing made of leaves or bark where trees grow, or the skin of an animal where trees are lacking, or warmer clothing is needed, to the manufactured and perhaps imported garment of wool, or cotton, or silk. Again, there is the increasing variety of food, from that of primitive man, supplied directly where he lives, to the highly varied diet found in a civilised community to-day, to which distant latitudes are made to contribute their local delicacies.

All these changes man has brought about. But he cannot change his climate. Slight local modifications may be secured here and there, as by planting trees to serve as wind-breaks, or perhaps by increasing the relative humidity a little through the construction of an artificial reservoir. No such modification is possible in man’s climatic environment as has been accomplished on the surface of the land under human agency. The atmosphere is as essentially unalterable as it is all-pervading. When we see how plants and animals are affected by atmospheric conditions, it is not unreasonable that we should expect man to show effects of a similar kind.

_Some Old Views Regarding the Effects of Climate on Man._ It is, however, easy to go too far in calling upon climate to explain phenomena which we may otherwise find it difficult to account for. This was the mistake formerly made by many writers on this subject, as has been clearly pointed out by Ratzel in his _Anthropogeographie_, where he gives an outline of many of these earlier views. Maupertius and others held that the colour of man’s skin becomes paler with increasing distance from the equator. Livingstone wrote that in Africa religious ideas also seemed to depend on distance from the equator. One writer held that cold produces a small stature; another believed that the Pygmies are small because of the heavy seasonal rains which fall in hot equatorial Africa. Climate was believed to explain the over-hanging eyebrows and partly-closed eyes of the negro; the small eyes and beardless faces of the Chinese; the (supposed) fact that more twins were born in Egypt than elsewhere. And so on. The broad generalisations of Montesquieu, Voltaire, Buffon, Hume, Buckle, and others, furnish interesting reading, and contain much that is suggestive and instructive, but they usually carry us well beyond the range of reasonable probability. Even Hippocrates’s observations on climatic controls are not without value to-day.

_Factors in the Problem Other than Climate._ To most of these older writers climate meant more than it does to-day. It included much of what is now termed our whole physical environment. Moreover they based their conclusions upon incomplete records, covering far too short periods of time. It must be remembered that we are dealing here with large, important, highly complex phenomena. Man moves readily from place to place, from climate to climate. His food, drink, habits, occupations; to some extent his physical and mental characteristics, change in consequence. Inheritance, intermarriage, environment, opportunities, soil, and many other factors enter in to determine what changes individual man and the race as a whole shall undergo. Time is a very important element in the final result, for in time a gradual adaptation to new conditions takes place. Climate is but one of many controls, albeit a most important one, for it largely determines what many of the other factors, such as diet, customs, and occupations, for example, shall be. The task of giving climate its proper place as a factor controlling the life of man as a whole is a difficult one, which cannot be definitely and satisfactorily solved to-day, or to-morrow.

It would take us far beyond the limits set for our present volume were we to attempt any consideration of the many complex problems in connection with the possible influences of climate upon the physical and mental characteristics of man. Investigations along these lines have given rise to much debate. It is our present purpose merely to point out some of the more simple and obvious ways in which the life of man is controlled by climate. This control, it should be observed, is either direct, where physical and mental changes under climatic stimulus are concerned, or indirect, as when climate acts upon man through its influence over the distribution of the animals and plants upon which man depends for his food, clothing, and materials of various kinds.

_Climate and Habitability._ Climate determines both how and where man shall live. It classifies the earth’s surface for us into the so-called habitable and uninhabitable regions. The deserts of sand and the deserts of snow and ice, whether the latter be near sea-level or high up on mountain tops, are alike climatic, the former because of aridity; the latter because of cold. The only non-climatic deserts are recent lava-flows. Where a soil is present which is not frozen for much over half the year, and where there is reasonable temperature and sufficient rainfall, plants and animals are found, ranging from few and lowly forms where conditions are the hardest and where all organic life is especially adapted to these conditions, to the greatest abundance where conditions are most favourable.

Man is influenced by much the same controls as those which affect plants and the lower animals. From the highest latitudes he is excluded by cold. The higher altitudes are hostile both because of cold and of diminished pressure. The deserts of sand are uninhabited, or thinly populated, by reason of aridity. Forests, where rainfall is abundant, are unfavourable to a dense population. The trees must be cleared away before settlement is easy. Man is widely distributed over the earth’s surface. In his migrations he has carried with him, beyond their original limits, many plants and animals. Ratzel points out that the coldest place in the world in January is a large Siberian city, Verkhoyansk, while one of the hottest places in the world is Massowa, on the Red Sea, the capital of the Italian colony of Eritrea. But the life of man is harder here and easier there, according to climatic conditions and the scarcity or abundance of plant and animal life.

Man is distributed in great belts around the world, corresponding roughly to the broad zones of vegetation, desert, steppe, and forest, the limits of which are set by temperature and rainfall, but man is much more dependent on rainfall than upon temperature. Water he must have, directly from the clouds, or indirectly through rivers, or springs, or wells, or from melted snow and ice. There are certain common conditions of life which affect the people who live in the same zone in the same broad, general way, just as these zones have similar general conditions of winds and of rainfall. This, as Ratzel has pointed out, means that there is a climatic factor at work to maintain differences between the people of different zones, in spite of the great movements which are constantly tending to produce uniformity. Obviously, the differences in the life of man which depend upon climate will be most noticeable, and will be likely to have the greatest historical significance, when marked differences of climate are found close together, as in the case of mountain ranges like the Alps, or of a pronounced lowland, plateau, and mountain topography like that of Peru or Mexico.

All the regions of sparse population are gradually being encroached upon by an invasion from their borders. Forests are being cleared and replaced by open agricultural lands. Wheat and corn are replacing grass on the steppes and savannas, especially where irrigation can be practised. Deserts are being reclaimed for farming here and there where water is available. The more civilised man becomes, the denser the population which the different parts of the earth can be made to support. From the wandering hunting and fishing tribes of the African forest or of the borders of the Arctic sea, through the farming populations of the cleared forest and of the steppe, to the crowded industrial centres of the modern city, there is such a gradation. It is the story of a more complete to a less complete mastery of man by his environment. But in spite of all that man can do, the larger climatic limitations persist. The Greenland desert of snow and ice, and the Saharan desert of sand, must remain practically deserted.

_The Development of the Tropics._ Within the tropics, under the equatorial sun, and where there is abundance of moisture, animal and plant life reach their fullest development. Here are the lands which are most valuable to the white man because of the wealth of their tropical products. Here are the tropical “spheres of influence” or “colonies” which are among his most coveted possessions. It is in this belt that food is provided for man throughout the year without labour on his part; in which frost and drought need not be feared; where shelter and clothing are so easily provided, and often so unnecessary, that life becomes too easy. Nature does too much; there is little left for man to do. The simplicity of life, so far as providing food is concerned, has been emphasised by many writers. We are told that three bread-fruit trees furnish enough food for one man; that a labourer needs only twelve bananas for his daily food; that one day a week is enough time to spend in caring for a manioc plantation; that two days’ work a week is often enough to enable a man to support a family; that a month’s labour will provide for a Malay more sago than he can use in a year, etc. Stories are told of shipwrecked seamen in the tropical Pacific who lived for many days on one cocoanut a day for each man. Captain Cook put the case very emphatically when he said that a South Sea Islander who plants ten bread-fruit trees does as much towards providing food for his family as does a man in northern Europe who works throughout the year.

In a debilitating and enervating climate, without the necessity of work, the will to develop both the man who inhabits the tropics, and also the resources of the tropics, is generally lacking. Voluntary progress toward a higher civilisation is not reasonably to be expected. The tropics must be developed under other auspices than their own. “Where nature lavishes food and winks at the neglect of clothing and shelter, there ignorance, superstition, physical prowess, and sexual passion have an equal chance with intelligence, foresight, thought, and self-control.”[27]

[27] John R. Commons, _The Chautauquan_, May, 1904, p. 222.

There is no superfluous energy for the higher things of life. Thus it has come about that the natives of the tropics have the general reputation of being indolent and untrustworthy; of always being ready to put off until “to-morrow.” Obviously, no such sweeping generalisation is to be taken too literally, for the lower latitudes have produced many men far from deficient in physical and intellectual power. Moreover in those parts of the tropics where natural conditions are more severe, the natives are usually more industrious. But it is true that the energetic and enterprising races of the world have not developed under the easy conditions of life in the tropics. As Edward Whymper’s Swiss guide said of the natives of Ecuador, “it would be good for tropical peoples to have a winter.” Guyot has put the case in this way:

A nature too rich, too prodigal of her gifts, does not compel man to snatch from her his daily bread by his daily toil. A regular climate, the absence of a dormant season, render forethought of little use to him. Nothing invites him to that struggle of intelligence against nature which raises the forces of man to so high a pitch, but which would seem here to be hopeless. Thus he never dreams of resisting this all-powerful physical nature; he is conquered by her; he submits to the yoke, and becomes again the animal man,—forgetful of his high moral destination.

The movements of the body, the habit of carrying loads on the head, even the native dances, have been thought by some to show the enervating effects of the climate. One writer has even gone so far as to see similar effects in the domestic animals, which he believes to be more docile than those in extra-tropical latitudes.

_The Labour Problem in the Tropics._ “What possible means are there of inducing the inhabitants of the tropics to undertake steady and continuous work, if local conditions are such that from the mere bounty of nature all the ambitions of the people can be gratified without any considerable amount of labour?” In these words, Alleyne Ireland well sums up the labour problem in the tropics. If the natives are, on the whole, disinclined to work of their own accord, then either forced native labour, which is contrary to the spirit of the times, or imported indentured labour, becomes inevitable if the tropics are to be developed. With few exceptions, and those where the pressure of a large population necessitates labour, effective development has been accomplished only where imported Chinese, Japanese, or coolie labour has been employed, under some form of contract. Negro slavery began in the West Indies, under early Spanish rule, and its perpetuation was certainly in part aided by climatic controls. The best development of many tropical lands depends to-day upon Chinese labour. It will be so in the Philippines. In Java, Holland has succeeded by forcing the natives to work.

With a large native class which is indolent, working intermittently for low wages, or which is bound under some form of contract, it follows that the native or imported labouring classes are separated by a broad gulf from the upper, employing class, which is usually essentially foreign and white. The latter class tends to become despotic; the former, to become servile. Marked social inequalities thus result, accentuated by the fact that the foreign-born white is usually debarred from all hard labour in a hot tropical climate. White labourers are not likely to become dominant in the tropics for two reasons:—first, because the climate is against them; and second, because the native is already there, and his labour is cheaper. White men are not doing the hard daily labour of India, or of Java, or of the Philippines, or even of Hawaii. They are directing it.

_The Government of Tropical Possessions._ The government of European possessions in the tropics has thus far been determined chiefly by three considerations: (1) The general incapacity of the natives, through ignorance, or lack of interest, or their undeveloped condition, to govern themselves properly. (2) The fact that the white residents are generally comparatively few in number and are only temporarily in the country, to make money and then to go home again. The white population is often composed chiefly of men—soldiers, officials, merchants, adventurers. There is little inducement to found permanent homes. (3) The marked class distinctions already referred to. These generalisations must obviously not be carried too far. Hawaii, very favourably situated as regards climate, will in time become an American State, and Brazil, most of whose immense area is typically tropical, has an increasing European immigration of permanent settlers. But what has been said is, in the main, true. The white residents constitute a caste, and naturally become the rulers, the home government retaining general control, often by force of arms. The native population, although largely in the majority, may have little or no voice in its own government. This is clearly not a democracy. It thus comes about that the tropics are governed largely from the temperate zone; the standards, ideals, motives, come from another land. And where governed under their own auspices, as independent republics, the success has not been great. Buckle first strongly emphasised the point that hot countries are conducive to despotism and cold countries to freedom and independence; and James Bryce has recently clearly set forth the climatic control of government in an essay on “British Experience in the Government of Colonies” (_Century_, March, 1899, 718-729). The very Europeans who exercise the controlling power in the tropics, themselves tend to become enervated if they live there long; they lose many of the standards and ideals with which they started; they not uncommonly tend to fall towards the level of the natives rather than to raise the standards of the latter. The peculiar situation which may arise from the government of a tropical possession in which the white race does not become acclimated has been emphasised by Dr. Goldwin Smith in a recent discussion of British rule in India. “British Empire in India,” he says, “is in no danger of being brought to an end by a Russian invasion. It does not seem to be in much danger of being brought to an end by internal rebellion. Yet it must end. Such is the decree of nature. In that climate British children cannot be reared. No race can forever hold and rule a land in which it cannot rear its children.” The future of tropical possessions and “spheres of influence” offers many problems of great complexity, the solution of which is largely controlled by the factor of climate.

_Primitive Civilisation and the Tropics._ There are reasons for thinking that primitive, prehistoric man, in his earliest stages, when most helpless, was an inhabitant of the tropics; that he lived under the mild, uniform, genial climate of that zone, where food was easily obtained and protection against the inclemencies of the weather least necessary. There has been a belief that southern Asia, bordering on the Indian Ocean, with its numerous bays, was probably the cradle of humanity. Civilised man is believed by many to have appeared first on the delta formed at the head of the Persian Gulf by the Tigris and Euphrates rivers, where also wheat was very likely first grown. Ancient civilisations seem to have developed in the drier portions of the tropics, where irrigation was necessary in order to insure abundant and regular crops, and where lived races more energetic and more hardy than those of the damper and rainier portions of the tropics, with more luxuriant vegetation. As Professor Hilgard[28] has well said:

[28] E. W. Hilgard: “The Causes of the Development of Ancient Civilisations in Arid Countries,” _No. Amer. Rev._, vol. 175, 1902, p. 314.

It is hardly doubtful that the ancient ‘Kulturvölker’ recognised these advantages (of irrigated lands) by experience, and eschewed the laborious task of rendering cultivable the comparatively infertile, or, at least, readily exhausted, lands of the forest regions.... And it is also clear that, inasmuch as the establishment and maintenance of irrigation canals necessarily involve coöperation, and therefore a rather high degree of social organisation, the conditions of the arid regions were exceptionally conducive to the establishment of the highly complex polities of which the vestiges are now being unearthed in what we are in the habit of calling deserts.

Civilisation was thus probably first developed, not where the overwhelming superabundance of nature’s gifts seems to offer the best conditions, but where man was under some stress of labour, some spur to effort, in less favourable natural conditions, but such as developed him. Within the tropics, the greatest progress later came, not on the damp lowlands, but on the less fertile plateaus of Mexico and of Peru, where the Aztecs and Incas made their marvellous progress in the drier, cooler, and more rigorous climates of altitudes over 7000 or 8000 feet above sea-level. Ratzel has pointed out, in the case of the ruins found on the lowlands of Yucatan and of farther India, that when such building operations are carried through by the autocratic rule over a subject class, the situation is very different from that in which we see spontaneous action on the part of a whole people.

The nations living in ease on the tropical lowlands were naturally, from early days, the object of frequent attacks and invasions at the hands of the more active and more warlike races living in more rigorous climates farther north, or at greater altitudes on mountains or plateaus. The invading tribes, having in time become enervated by an easy existence on the warm lowlands, have themselves often been later overcome by a new enemy from the north. Some of the greatest migratory movements in history have taken place from colder to warmer climates, as part of this general equatorward tendency in both temperate and tropical zones. The barbarous tribes broke through the northern passes and descended onto the more genial and more fruitful lowlands of India, being helped to do this by the ease of the descent. Such mountain systems as the Himalayas, or the Alps, stretching east and west, are natural climatic divides between more genial and more severe climates, and have often been crossed by invading armies from the north. The descent of the Aryans into India; the Manchurian conquest of China; the invasions of Greece and Italy from the north; the southward movement of Toltecs and Aztecs in Mexico, have been cited as illustrations of this equatorward tendency. In the southern hemisphere, it has been suggested that the Kaffirs have shown the same tendency—there northward,—as did the native Patagonians in their predatory expeditions to the north. The equatorward tendency may be seen to-day in the extension of European “spheres of influence,” especially in Africa, the object now being essentially a mercenary one, and not a seeking for new homes in a more genial climate.

_Dwellings in the Tropics._ Dwellings, clothing, and food are easily provided in the hot climates of the moist tropics. In the deserts and on the mountains the conditions of life are harder. The protection that is needed against sun and rain, and the lowered temperatures of the tropical night, is usually very simple. Man spends most of his life outdoors. The building materials are ready at hand and simple. Many of the primitive native huts are loosely made of bamboo or other pliable trees, where such are available (_e. g._, the mimosa used by the Hottentots); of palm and cocoanut leaves, sugar-cane, or grass. Pointed roofs, supported on poles, and wooden frames with mats for walls, are a characteristic style of architecture. In some places temporary huts are made of skins, while more permanent dwellings are better built, with good roofs. The permanent dwellings in tropical cities are oftenest built of stone, with thick walls. The old Spanish and Portuguese idea was also to have narrow streets, in order that the sunlight might be shut out as much as possible. In the newer portions of tropical cities, however, wide streets and fine boulevards are being laid out. In the modern houses built for European residents in the tropics, the rooms are large, airy, and well ventilated; there is a minimum of furnishings; there are broad verandas with screens for protection against the sun; there is a proper air space between roof and ceiling. Stoves and fireplaces for heating purposes are unnecessary, and the absence of chimneys on the tops of city houses has often attracted the attention of newcomers from colder latitudes. Nevertheless, in some places the natives are so sensitive to the nocturnal cooling that they keep themselves warm by fires at night. Much difficulty is experienced on account of the destructive action of ants and other insects, and of the dampness, as well as of sudden tropical rains and floods. Even in dry climates, buildings do not last well, unless built of stone. As the prevailing winds are easterly, the eastern quarters of the cities are usually the more desirable and the more fashionable, and are therefore inhabited by the wealthier classes. It is the habit of those who live in the tropics to stop work and stay indoors during the hottest part of the day. Business is done in morning, or later afternoon, and the afternoon _siesta_ has become a characteristic of the people. The late afternoon is the time for the fashionable outdoor life in the park, on the promenade, or at the club.

_Clothing in the Tropics._ The clothing of the natives of the tropics is of the simplest kind, often so scanty as hardly to be called clothing at all. In the moister portions it not infrequently consists solely of aprons made of grass, leaves, bark, or reeds. The children generally go naked. Where the diurnal temperature changes are marked, heavier clothing is usually worn at night. The clothing of Europeans and Americans is loose and light in colour and weight, but thin woollens are by no means to be discarded altogether, for they are useful during the cooler evening hours. Light headgear, for protection against the sun, such as wide-brimmed straw hats or pith helmets, sun umbrellas, and low shoes are used. Great care has been taken to devise the most suitable uniform for white troops in the tropics, even down to the most minute details of equipment. The kind of material, the number and cut of the different garments, even the best kind of belt and shoulder-straps, have received attention. Campaigning in the tropics is very different from ordinary service in the temperate zones, and all these details need care. It is the general opinion that a loose, light uniform, of porous material, with a minimum of straps, belts, and pouches, is the best. As to materials, khaki has come into extensive use and is very popular. “Keep the head cool and the abdomen warm” is the best rule for white residents of the tropics to follow.

_Food in the Tropics._ Fruits, especially the banana, cocoanut, and bread-fruit, and rice, manioc, yams, sago, and sugar-cane are staple articles of food. Meat and fish are not much used. In the deserts the date-palm is an important article of food, and where irrigation is practised a variety of cereals and fruits is usually grown. Of late years, much attention has been paid by military officials to the question of the best ration for white troops who serve in the tropics. The general feeling is that a light diet consisting chiefly of fruit, vegetables, and cereals, with a minimum of nitrogenous, heat-producing foods, is the most likely to keep the men in good health. A light midday meal is recommended. There are, however, those who hold that the prevailing anæmic condition of the tropical natives is largely due to the deficiency of meat in their diet, and who therefore urge that meat should be eaten in reasonable quantity.

There is much difficulty in preserving perishable food products. Such articles sent from cooler latitudes for use in, or for transportation across, the tropics, need special protection, by refrigeration or quick carriage. The increase of transportation by steam in place of sail, and the opening of the Suez Canal, have both been factors of importance in meeting this difficulty. It is distinctly an advantage for a country to sell its food products to other countries on its own side of the equator. Frozen meat, carried long distances by sea across the tropics, is not as good as fresh meat, and is also poorer than meat carried at sufficiently low temperatures to preserve, without actually freezing it. The need for preserving perishable food has led to an increasing demand for ice, and hence to the multiplication of artificial ice plants. Recently there comes a demand from one tropical country (India) for refrigerator cars for the transportation of milk.

_Agriculture, Arts, and Industries in the Tropics._ The need of labour in order to procure a good return from the ground is so slight that agriculture has not yet made much progress in the tropics as a whole. Where frost need not be feared, where crops ripen all the year around, and where the soil is rich with decaying vegetable matter, agriculture is naturally slow to improve. Yet there are native peoples who have advanced much farther than might be expected, as is seen, for example, in the cultivation of rice in the Malay archipelago and in farther India; in the state of Polynesian agriculture; in the success at farming attained by many negroes in Africa. Tropical soils are by no means all as fertile as is generally believed. The warm rains throughout the year leach out the soil, carrying off many salts and leaving the land poor; the laterite soils which are common in the tropics are very poor in plant food ingredients.

There have thus far been comparatively few native industries in the tropics, for the reason, doubtless, that the necessities of life are readily supplied without the need of manufacture. In the future, with increasing exploitation by the white race, and under the control of it, and with growing demands on the part of the natives themselves, tropical industries are certain to develop. Yet many tropical natives show great ingenuity in the use and adaptation of the simple natural products to which they have access. Thus the shell of the cocoanut is made into bowls and other utensils; the cocoanut fibres are plaited into thatch, baskets, and mats; the cocoanut stems are used in the building of houses and boats. Grass and reeds are plaited, and the bark-cloth of the Pacific islanders and of central Africa is so widely used, and serves its purposes so well, that it has very probably kept the natives who use it from advancing to weaving and spinning. Bamboo and rattan are widely used for domestic utensils of all sorts; for hunting and agricultural implements; in constructing houses, boats, rafts, and vehicles for transportation; in making pipes and musical instruments; and for other purposes; even for food, rope, and string. From the tropics man procures many things in addition to the plant products. For example, the warm tropical oceans yield him pearls and corals. It is an interesting fact that, at the present time, European countries, particularly Germany, are devising and manufacturing machines especially intended for harvesting and preparing for export the products of the tropics, such as machines for splitting cocoanuts; for preparing and extracting oil from the palm fruit; for making caoutchouc from the sap of the rubber tree, etc. Germany is also devising plans for tropical cultivators, railroads, and houses.

Special precautions are necessary in packing many manufactured goods that are to be transported across the equator, in order to protect them from injury by the dampness. Leather goods, textiles, and paper are liable to be stained. Arms, cutlery, and all metal goods need the utmost care to keep them from rusting. These are best preserved when packed in cases lined with some absorbent wood well saturated with hot paraffine wax. It has recently been pointed out in a Vienna trade journal, that the preservation of lacquered shoes sent from Europe to Australia depends upon the circumstance whether they may be kept moderately cool by the ocean water, low down in the ship’s hold, or are near the deck, exposed to the heat. In Indian warehouses woven goods are affected by the dampness in such a way that they have different lengths, although all uniformly woven. Even in the dry month of February, at Bombay, closely woven imported calicoes, exposed to the air, experience changes in length from day to day amounting to 3 per cent. Ordinary salt absorbs so much moisture in the damp latitudes that it has been necessary to prepare a salt which shall escape this difficulty.

_Some Physiological Effects of Tropical Climates._ We are not here concerned with the many complex questions, physiological and ethnological, which have arisen in connection with the effects of tropical climates upon man. There has been much debate concerning the effect of the climate upon the colour of the skin. It was natural that many early writers should see in the black skin of the negro an effect of the tropical sun, and should explain the paler colours, and white, as resulting from residence in higher latitudes. It was pointed out, _e. g._, that among certain tropical natives the women, who live indoors, are lighter in colour than the men, who are more exposed. It may be remembered that Darwin, in his _Descent of Man_, pointed out that the distribution of coloured races does not coincide with corresponding differences of climate, and that no change in colour has taken place in the Dutch who have lived for several generations in south Africa. Darwin also thought it not an improbable conjecture that the immunity of negroes from certain diseases might be correlated with the colour of their skins, and that this colour might have been acquired because darker individuals escaped during successive generations from these diseases. However opinions may differ concerning the origin of the black skin of the negro, it is clear that this colour is an advantage, rather than otherwise, in helping to cool the body through profuse perspiration and the resulting evaporation. Black skin, however it may have been developed, seems to be well suited to a hot climate. Major Charles E. Woodruff, of the United States Army, has lately maintained that the failure of the white races to colonise the tropics is due to the excess of light which there prevails, and not to the heat or humidity. He believes that the white man, especially the blond, gradually becomes disinclined to work on this account, grows neurasthenic, and finally breaks down. An effect of climate upon the kind of hair has also been claimed, but on this point, again, Darwin has noted that although there are reasons for thinking that the growth of hair is affected by cold and dampness, he had “not yet any evidence on this head in the case of man.” Schlagintweit called attention to the fact that the inhabitants of Nepal wore much less head-covering than Europeans, and did not suffer. The sallow, anæmic complexions of white inhabitants of the tropics are a subject of general comment.

There are other physiological matters which must also be passed over without discussion. For example, it is alleged that a preponderance of females in warm climates is the effect of the light diet of mothers in the tropics, whereas a meat diet produces more males.[29] Direct proof of the assertion that sterility in the white race ensues after three generations in the tropics is hard to find.

[29] Schenck: _Einfluss auf das Geschlechtsverhältniss_, 1898.

_The Equatorial Forests._ In the equatorial belt we find the hot, sultry, cloudy conditions of the doldrums, with frequent heavy rains. When the doldrums migrate north and south, and the trade winds take their place, there are clearer skies for a time, and little or no rainfall. There are two rainy seasons near the equator (_equatorial type_), and one rainy season farther away (_tropical type_). The life of man in the equatorial belt as a whole is controlled by the rains. The dense tropical forests of equatorial Africa, South America, the Malay peninsula and archipelago, grow where the rainfall is heaviest. These forests are dark and depressing; crowded with creepers and plants of innumerable varieties; rich in valuable woods such as mahogany, ebony, and rose-wood; in sap-products such as rubber, and in drugs such as quinine. Pöppig has compared the native South American tribes with their forest trees. Man develops rapidly there, as does the vegetation. He also ages rapidly, like the tree which decays at the time of its best development. The tropical tree does not strike its roots firm and deep into the soil; it spreads them out near the surface, and a high wind overturns it. So it is, according to Pöppig, with the native. Both he and his trees lack the stability and endurance of northern forests and of temperate zone man. There are comparatively few animals in the dense tropical forests. Reptiles, birds, and monkeys are found. The large mammals are in the more open country.

Such a superabundance of vegetation is unfavourable to human occupation. The population is small, and generally at a very low stage of civilisation, as illustrated by the Indians of the Amazonian forests or the Pygmies of the Congo, who wander about without settled homes. The trees and undergrowth act as a very effective barrier to the advance of civilisation from the margins of the forest. The difficulty and expense of travel and transportation, and of clearing the forest for purposes of agriculture, operate to retard the advance of civilised man. The waves of civilisation, as one writer has put it, beat up against the forest, but only occasionally break through it. The northern forests of Argentina, inhabited by wandering tribes of Indians; the densely wooded Amazonian provinces of Peru; the equatorial forests on the west coast of Africa; the forests of Achin, in northern Sumatra, in the protection they have afforded the natives in their resistance against the Dutch; the eastern forested slopes of Central America, left longest to the native tribes, while the western, more open, and drier slopes were first settled by white men and are best developed—these are all examples of the repelling effects of dense tropical tree growth where the advance of civilised man is concerned. Even the earlier American civilisations, the Aztec and the Inca, halted before forested areas. It has been pointed out that the Incas were almost as much hemmed in by the forests on the east as by the Pacific on the west.

In the equatorial forests the men hunt and fish; collect rubber or other forest products; do a little planting in the forest clearings, without paying much attention to the crop when planted. By clearing away the forest, these people might extend the area devoted to agriculture, and become farmers. In the clearings at the margins of the forests there is a certain amount of agriculture, carried on chiefly by the women, who are also occupied with domestic duties while the men are hunting or fighting. Settlements in these clearings are often abandoned. In the Malayan forest the natives are graded from those who are simple nomads to those who have settlements where they cultivate rice in the wet jungles. Rice needs much water, and its cultivation in Java is closely allied with the general question of deforestation. Where the sago palm grows, and provides food without the need of much labour, the natives are least advanced.

Travel through the forest is difficult. Darwin thought it not unlikely that the habit of carrying knives for the purpose of cutting down vegetation contributes much to the frequency of murder among the tropical peoples. Narrow paths, along which travellers move in Indian file, are natural ways of communication unless travel can be by boat, which is obviously quicker and easier. The natives thus naturally live along the rivers. It has been pointed out that there is a connection between the method of carrying goods in the African forests, on the backs or heads of negro porters, and the slave trade, which sells the man as well as the goods. Many of the natives who secure the rubber from the Amazonian forests, or from those of the Congo, are to-day subjected to hardships which equal those of slavery.

The seasonal floods on many rivers, the Amazon for example, oblige the natives to build huts on piles to keep them above the water. When the waters rise higher than the platforms, the people take to their canoes, until the flood is over. In some places the floods drive the people to the towns, which are built on natural eminences. In New Guinea and in the Mosquito Territory the natives live much in their boats during the rainy season. In fact, in the former country so much time is spent on the water that the people partly lose their ability to walk. They almost become amphibious beings. Sir Charles Eliot reports that some of the native tribes along the Bahr-el-Gebel, at seasons when mosquitoes are abundant, use platforms on poles ten or twelve feet high, as these insects do not fly far above the ground.

The food supply along the Amazon is closely related to the rise and fall of the water. When the river is in flood, the turtles, fish, and aquatic birds migrate to the northern tributaries, or even to the Orinoco, where the dry season is on. With the return of the dry season on the Amazon comes the opportunity of the natives to catch the fish and turtles, and to secure turtles’ eggs. There is thus a very general seasonal migration among the people. The flood time is the time of deficient food supply. This explains the origin of the native prayer for a good dry season. The conditions of life on the Mosquito Coast are very similar (lat. 10°-15° N.). The north-east trade there brings the dry season (spring), when the Indians collect the eggs of alligators and turtles on the dry sand-banks. Livingstone pointed out that during the great floods in the inland lake region of Africa the natives live upon, and cultivate, the large ant hills, in the Bangweolo and Moëro districts. On the plateau of western Nyassa, the Ba Bisa profit by the heavy rains in an interesting way. At such times the hollows are swampy, so that elephants driven into them become helpless and are readily killed. Similarly, as reported by Livingstone, the natives of the islands in the Zambezi River utilise the floods and canoes to hunt buffaloes, these animals being easily caught in the water. One writer has pointed out that certain African tribes purposely go naked during the rains, knowing that they are thus less likely to become chilled.

The great value of the tropical forest products is leading, and will still further lead, to the settlement of considerable numbers of whites on the margins of these forests, and along the rivers which flow through them. Thus in Brazil, along the lower Amazon and its tributaries, there are cacao, sugar, coffee, tobacco, manioc, and rice plantations; in some cases also, sugar factories, rice and lumber mills. Large cities and towns thus gradually grow up, like Para and Manaos, and the native tribes come more and more into contact with civilisation.

Travel and transportation are emphatically controlled by climate throughout the equatorial belt. Roads become almost or quite impassable during the rainy season. Lowlands, as in central Africa and in equatorial South America, turn into swamps or temporary lakes, so that all travel may be stopped. In other places, where boats are used at all seasons, the rains give high water and aid, rather than hinder, travel. The control of the floods of the Chagres River, on the Isthmus of Panama, is one of the most difficult problems with which the engineers have dealt. Work on railroads is always much interfered with during the rainy season, if not interrupted altogether. Dense tropical vegetation seriously obstructs railroad construction and operation. The roadway is constantly being overgrown, and men must be kept at work cutting down the weeds, underbrush, and trees. This involves great expense, and seriously reduces the earnings of the roads. Recently, tank-cars which frequently spray the right of way with a strong poison have come into use, as on the Guayaquil-Quito line in Ecuador, and on the Tehuantepec Railroad. Ties and trestles rot quickly, or are destroyed by insects. Special kinds of ties, such as _lignum vitæ_, or camphor wood, or even iron, have therefore been used. Although vegetation is thus a serious handicap to railroads in the moist tropics, it serves a useful purpose in preventing the sides of steep cuts from sliding down. The absence of frost makes possible cuts with steeper sides than in colder latitudes. Along the older portion of the Panama Canal, which has been built for some years, no masonry was needed to keep the banks from caving in. The heavy vegetation served the purpose of stone and cement. Fevers and other diseases common in the rainy season of the tropics are also a serious handicap, and floods and landslides add to the difficulties. The sultry heat is another obstacle. Curious complications in the employment of several different kinds of labour arose on the Uganda Railway. For four castes among the Indian workmen, four separate water-tanks had to be provided, and if the water in one tank gave out, that particular one had to be sent by train to be filled, although the remaining three tanks were full. Dr. H. R. Mill has pointed out that there are many features on the Uganda Railway which show climatic control. The cars are built of metal, in order to defy wood-boring insects. They have deep ventilators, protected by wire gauze against mosquitoes. The windows are of green glass to give protection against the glare of the sun.

During the dry season the difficulties are similar to those noted later under deserts. At that time dust makes travelling disagreeable, and instead of streams being impassable, they often dry up, and their beds serve as roads.

A curious relation of thunderstorms and navigation is reported by Hann from Maracaibo, Venezuela. The lightning flashes from rainy season thunderstorms at the south-western end of the lake of Maracaibo are used by captains in navigating their vessels through the strait of Maracaibo. “El Faro de Maracaibo,” as these lightnings are locally called, gives a good coin pass-direction for steering a ship on dark nights.

_The Open Grass-Lands of the Tropics_: Savannas. Between the forests on one side and the deserts on the other comes a transition zone of moderate rainfall. Here the forests are replaced by an intermediate belt of more or less open, grassy country, known as the savanna. There are usually a long dry and a shorter wet season (summer). Vegetation has but a short season for growth. Savannas are found in Africa and in South America both north and south of the equator. In Africa they include the Sudan; in South America, the llanos of Venezuela and the campos of Brazil; in Australia, the downs. The open country and the grass cover, which forms natural hay in the dry season, fit the savannas for grazing purposes. The people are essentially pastoral. Population is denser than in the tropical forest, and the people are more energetic and more advanced. The African savannas are abundantly supplied with large animals such as lions, tigers, antelopes, elephants, rhinoceroses, and giraffes.

Their dependence upon grass and water for their cattle forces the inhabitants of the savannas to be more or less nomadic, the more so the more pastoral the people are. They move their tents and household goods easily over great distances, stopping where there are pasturage and water. Their food is supplied chiefly from their flocks and herds, of cows, goats, or camels. Agriculture of a somewhat primitive kind is often combined with grazing in the better-watered portions of the savannas, the seed being sown at the beginning of the rains. The population there becomes more sedentary. Thus in the Sudan there is a belt of agriculture nearer the equator, where the rainfall is heavier, and a pastoral zone farther from the equator, where there is less rainfall. In these districts the rainfall varies much from year to year, and there are frequent droughts and famines. Thousands of persons may then die of starvation, as has happened in parts of the Sudan, in Nubia, and elsewhere within a few years. At such times the cattle die in large numbers, and where the herds have been lost by famine or disease it has happened that certain native tribes (_e. g._, the Galla, in eastern Africa), after suffering terribly from hunger, have changed their place of residence, turning in part to plunder and hunting, and in part to farming. A curious case of seasonal migration into the desert has been reported of the Tuaregs, who inhabit part of the region about Lake Chad. The upper class of these people is nomadic, and during the rainy season retires into the desert with its camels, which do not like the rains.

All the savannas will in time be more thickly populated and more valuable than now, owing to the availability of considerable portions of them for agriculture, especially where irrigation can be practised. Under the supervision of white overseers, the natives will become better agriculturists and cattle-raisers. In South America, as well as in Australia, the savannas are in part being sown to wheat. From the savannas and the neighbouring deserts, ivory, ostrich feathers, palm oil, dates, gums, and so on, are secured.

_Trade Wind Belts on Land: the Deserts._ The major part of the earth’s surface in the trade wind belts is a desert, which forms a marked feature of every rainfall map of the world. These trade wind deserts, because of their great extent, are of immense importance from a human standpoint. They are belts of scanty population. They form great barriers, across which even to-day travel and transportation are difficult and expensive. The interior of Africa has been out of contact with the civilised world largely because of the deserts to the north and south of it. Goods and passengers go around, rather than across them. Trails across the desert are easily effaced by blowing sand, or are shifted as some oasis dries up. Along their margins, where there is a moderate rainfall, or where oases, wells, or streams make permanent settlement possible, the population is more or less sedentary, agricultural, pastoral, and commercial, but even here droughts and famines may occur, and agriculture is not absolutely sure. Rivers which cross the desert gain their water from the rainier lands beyond, and then flow long distances without tributaries. The Nile is the classic example of this. Along such rivers population naturally gathers; irrigation and agriculture are practised, and the entire valley becomes an oasis. The Nile and the rivers of the coastal desert of South America are illustrations; in the Deccan, also, the river systems are the centres of the densest population. It is difficult to overestimate the effect which the Nile had upon the civilisation of ancient Egypt. It has been asserted with good reason that the annual overflow, by depositing silt and by wiping out the boundaries of individual tracts of land, obliged the ancient Egyptians to develop mathematical skill in re-surveying these lands, as it also led to canal and dam building. Where deserts are irrigated, it is sometimes necessary to guard the water supply, as in Chile and Peru.

In the desert proper, a nomadic life and a scattered population are characteristic and inevitable results of the aridity. As Schirmer has expressed it, “the purer the desert, the more the inhabitants disperse themselves.” The Saharan nomads camp for a few months in winter, it may be near the towns, and then travel with their flocks in summer. The Bedouins, although they wander to and fro over a wide area, nevertheless keep within certain recognised limits. In the desert, population gathers in the oases, as on islands. Here the trails followed by the caravans come together, like sailing routes at sea. Thus there is naturally developed a settlement, in which the people are in places so crowded that they may be on the verge of starvation all the time. There are small Arabian towns where the houses are almost crowded on top of one another, producing something not unlike the modern “sky-scraper” of an American city, where land is scarce and expensive. When such oases dry up, or are encroached upon by the desert sands, they are abandoned, and the ruins, later discovered by some explorer, give the impression of a diminishing population.

The climate of the trade wind deserts is drier and more stimulating, and has larger temperature ranges, than that of the forests and of the savannas. The need of protection against heat and cold is greater; food more difficult to obtain; life a harder struggle. Therefore the desert produces more active, more energetic, and more progressive men. They are independent, bold, and strong. Nachtigal has pointed out the difference between the healthy and vigorous tribes of the Sahara and the less active Sudanese. The hardy, warlike inhabitants of the desert of Persia and Baluchistan have frequently held in subjection the people of the richer lowlands on the west. There is a well recognised difference between the true nomad desert-dweller and the weaker sedentary. From the latter, the former often takes tribute, and if the exactions become unbearable, the unfortunate sedentary farmer may be forced in self-defence to become a nomad himself. The nomadic life of the desert-dwellers tends to make robbers of them, so that pillaging of caravans is not an uncommon occurrence. The utter hopelessness of the isolated Australian desert seems to have led to a most degraded condition among its inhabitants. Nearly naked, living on the lowest forms of desert life, and practising cannibalism and the murder of the weak and helpless, they have ranked among the lowest human beings in the world.

The trade wind deserts are gaps in the map of the world’s civilisation. When the tribes or individuals who live along the margins of the deserts are forced into the deserts, they tend to scatter and disappear. There are also migrations out from the desert into the more fertile regions adjoining, as in the case of the Tuaregs in the Sudan. The advance of the nomadic Arabs from the Sahara into the lands of the more peaceable agricultural negroes to the south has been compared with the encroachment of the desert sands over some fertile grass-covered land along its border.

The more permanent dwellings often have flat roofs, and are built of stone or adobe, wood and vegetable products being scarce or entirely lacking. Sloping roofs are not needed, as the protection desired is not against rain, but against sun and wind. In hot, dry climates the flat roofs are generally used for sleeping at night. The houses are low, sometimes even partly underground, for better protection against the wind. When the people are on the move tents are taken, made of skins or, where the materials are obtainable, of thatch, palm leaves, or grass. The timber usually comes from the date tree. On the arid west coast of South America the Incas used adobe bricks chiefly in the regions with least rainfall, and granite and porphyry on the rainier plateaus. Even the great Inca temples, built of massive stone blocks, had light thatched roofs, because but little protection against rain was necessary. In the Chilean desert many of the richest mines were discovered in the early days by men who were hunting for firewood or tending cattle.

The nights are often cool, and heavier clothing is worn than by day. Both clothing and food are simple, and are supplied chiefly from the flocks and herds, which are the desert inhabitants’ most precious possession, or from desert plants, such as the date. Along the shores of the Persian Gulf, where there is no wood supply, even boats are made of date leaves. The dry desert air preserves rather than destroys. Sun-dried meat may become an article of food, as in the _charqui_ of Peru. Livingstone and others have noted that the desert peoples of Africa are much less clean than those who inhabit the moister parts of the tropics. The lack of water, as well as the belief that water makes the skin sensitive to the heat, leads to a great lack of cleanliness. In Abyssinia, Nubia, and elsewhere, a kind of sand bath is substituted for the usual bath with water. Protection against dust and sun is found by covering the head and wearing a veil, as is done, for example, by the Tuaregs, who are completely covered with the exception of their eyes. Some tribes blacken their eyelids and their faces, just as is done by people in the Himalayas as a protection against snow-blindness. During dust storms and high winds all protection may be inadequate, and death may result.

Utensils of all sorts are made chiefly of leather. In Nubia, as reported by Speedy, baskets are so closely woven of leather strips that they are fluid-proof. As these cannot be placed on the fire, milk is warmed by dropping red-hot stones into them. Many desert people become adepts at plaiting and weaving in leather. Well-digging is an occupation in which many of the Saharans have by nature been forced to become skilled. Here and there salt, nitrate, or borax deposits locally give an exceptional economic value to the desert, and furnish employment to many. Salt may become an important article of exchange. The amount of nitrate exported from Chile is determined largely by the weather and crop conditions of Europe.

That deserts have had a significant relation to religious ideas has been suggested by several writers. Ernest Renan points out that the desert is monotheistic, its uniformity suggesting a belief in the unity of God. The desert is conducive to a solitary, meditative life; even to a morbid and fanatical state of mind. Such conditions, it is believed, furnished good ground for the growth of such a religion as Mohammedanism. In his _Seas and Skies in Many Latitudes_ (London, 1888, pp. 42-43), Abercromby gives two maps, showing respectively the areas of Mohammedanism and the districts in Asia and Africa with a mean annual rainfall of less than ten inches. The maps are strikingly similar. The author adds: “Whether this distribution of a great creed is the result of chance, or of some deep connection between the tenets of that religion and climatic influences, I cannot say;—but still the relation is so remarkable that I have thought it well to bring the matter forward.” The rain-ceremonies and rain-dances among the native tribes of central Australia; the Indian celebrations of the rise of water in the Peruvian rivers; the ancient Aztec sacrifices to the god of rain in Mexico, and other similar customs in tropical deserts, are natural in a region where water is of supreme importance. In one of the Australian rain-ceremonies, the men dance around a mimic water-hole, imitating the calls and motions of aquatic animals. These dances are reported as being carefully timed, by experienced individuals, to come at the seasons when rain is likely to fall.

The night is cooler and less dusty than the day, and is the best time for travelling. The camel, which can go long without food and water, is the natural beast of burden. Trade is still largely carried on by means of caravans, which require camels and drivers, and give employment to many men. The construction of railroads across these deserts will present the same difficulties which have already been met in the arid regions of the temperate zone. Ties dry up and twist; the danger from fire is greatly increased, often necessitating fire patrols; fuel is expensive and must be imported, unless a poor local fuel, like sheep or llama dung, is used; water for men and locomotives must be brought in by water-trains, tank-cars, or pipeline, or locally distilled, at considerable expense; cloud-bursts sweep away bridges and tracks; the number of working hours by day is reduced by the heat; drifting sands cover the track and must constantly be shovelled off; the blowing sand hinders seeing, and increases friction and wear on the rolling stock; watchmen to guard against accidents from blowing sand on the track must be employed; proper non-dusty ballast is difficult to secure; all lumber must be brought from moister regions. On the other hand, the trade wind deserts are, on the whole, healthy regions. When the Sahara and the Australian desert are bridged by railroads, and when the South American coastal desert is traversed by a longitudinal line of track from north to south, the relations of these great arid regions to man will inevitably be greatly changed.

_Trade Belts at Sea._ At sea, the trade wind belts are closely related to man through their control over sailing routes, and over voluntary and involuntary migrations. A glance at any pilot chart will show that all sailing routes which pass through the trade wind belts in any ocean are determined by the course of these winds. The route from Europe to India furnishes a good example of the advantage that is taken, by mariners of the present day, of the prevailing wind systems of the world. In former times a vessel was kept close in along the west coast of Africa, amid calms and adverse winds, and then, after passing the Cape of Good Hope and leaving Mozambique, she waited for the blowing of the south-west monsoon, with which she continued her voyage to India. In 1500, Cabral sailed from the Cape Verde Islands out into the open sea with the north-east trades, avoiding the African coast. Keeping far to westward he discovered Brazil; continued across the south-east trade, rounded the Cape of Good Hope with the westerlies, and then proceeded up the east coast of Africa as had previously been the custom. In the 17th century the Dutch struck off on the new route from the Cape of Good Hope, making their easting in the prevailing westerly winds of the South Indian Ocean, and then sailing up to India with the south-east trade. The passage across the equatorial belt of calms (doldrums), which was formerly much dreaded, is now so carefully worked out that vessels may cross where the belt is narrowest, and where there is therefore the least danger of delay.

Steady winds like the trades certainly tempted the early navigators to put to sea. The famous voyage of Columbus, when he discovered America, was facilitated, if not made possible, by the north-east trade. The easy outward voyages of the early Spanish adventurers and colonists took them naturally to that portion of the Americas where they found climates in which they and their descendants could live, while to the Anglo-Saxon originally fell the North American continent, with its more rigorous climate. The monsoons of India have, from the earliest days of trade with the East, been important agents in aiding commerce. In the Mediterranean, the Etesian winds—the northward extension of the trade—favoured early commerce. The migrations of the Malays to the Melanesian Islands, of the Polynesians, and of other Pacific islanders, found their occasion and their possibility in the prevailing winds of those latitudes. The islands from the Philippines to the Gilbert Islands are in the north-east trade and from the Moluccas to the Society Islands in the south-east trade. Thus intercourse and migrations are easy. In the archipelago of the monsoon belt south-east of Asia trade depends largely upon monsoons. An interesting case is cited by Ratzel, on the authority of von Maltzan. Two small ports, Bîr Ali and Megdaha, lie opposite one another on the southern coast of Arabia, in a small bay. The former is protected on the west, and the latter on the east. Hence the former is sought by shipping in summer, and the latter in winter. Both places have grown and really make one town, the officials and many of the inhabitants moving twice a year with the seasonal change of wind. The war expeditions of the native tribes of this great island region have always been governed by the monsoons. In many places to-day native boats do not venture to sea at the height of the monsoon. In the discussions regarding the relative advantages of the Nicaragua and Panama Canal routes, much emphasis was laid upon the prevailing winds in the two cases. Many of the optimistic predictions concerning the use of the Panama Canal by sailing vessels did not take account of the calms and variable or adverse winds to be encountered before entering and on leaving the canal, which necessitate transportation by steamer, or at least some towing of sailing vessels.

To leeward of the west coast of Africa navigation is not infrequently interfered with by the so-called “tornadoes,” which move westward off the land, and by dust storms, which obscure the air and delay progress.

Tropical cyclones at certain seasons and in certain parts of the trade wind belts at sea not only damage shipping, but often devastate towns, bridges, and crops, bringing starvation, poverty, and not infrequently pestilence as well, owing to decaying animal matter, or fish thrown up by the sea. Thousands of lives have been lost as the result of such disasters. The Pacific islands are particularly unfortunate in this respect. The storm waves produced by these cyclones are especially severe at the head of the Bay of Bengal. Native huts are easily blown over by the cyclonic winds, and it has been pointed out that the huts elevated on high posts in New Guinea, and swaying with the wind, furnish good evidence that the district in which they are found is not visited by tropical cyclones. In some places, Mauritius, for example, houses are provided with shutters to be used in case of a cyclone, and in many places the natives have resistance to cyclones in mind when they build their huts. In time, buildings must be erected in the tropics which will withstand these storms better. Worcester reports of the Philippines that in order to save the banana trees from destruction by typhoons, some of the natives cut off all the larger leaves when the approach of a typhoon becomes evident.

_Monsoon Districts._ Of the monsoon districts on land, India is the largest example. The two seasons are strongly contrasted. The success or failure of the crops depends upon the amount, distribution, and time of occurrence of the summer monsoon rains. Famine follows when these rains are deficient or unfavourably distributed, with terrible suffering and the loss of thousands of lives among men and cattle. Lately the government of India, at great expense, has undertaken relief works during times of famine, including irrigation works. The amount and regularity of the water supply is the chief factor in determining the density of population in India.

Travel and transportation in monsoon districts depend closely upon the season. During the rains, the roads are likely to be bad or impassable, and landslides and washouts are common. In the Philippines the mud is so deep that sledges are used instead of wheeled vehicles. Communication may be entirely interrupted by floods. Campaigning under such conditions is extremely difficult, as was abundantly proved during the American occupation of the Philippines. Horses, and even water-buffaloes, were often unable to haul the guns, one of the difficulties with the buffaloes being their need of a mud bath in the hottest part of the day. During the early part of the American campaign in the Philippines the success of the American army was achieved in the dry seasons, the natives gaining the upper hand, or at least making the most progress, during the rains, when conditions were hardest for the white men.

Native dwellings are adapted to the different seasons, as on the island of Mindoro, where the Mangyans erect simple shelters of rattan and leaves wherever they happen to be in the dry season, while in the rainy season the dwellings are more elaborate and more secure. The rain hat and coat of the Filipinos; the preparations made in north-western Mysore, on the summit of the western Ghâts, in laying in provisions to last during the long rainy season, as if it were for an extended voyage at sea; the general use of punkahs, tatties, grass mats, etc., for cooling purposes during the hot and dry season in India and Persia, these being often wet, and kept in motion by coolies; the habit of closing houses during the day and of staying indoors during the hottest hours,—these few cases may suffice to illustrate the control of climate over the life of man in the monsoon belts.

_Tropical Mountains._ Their “temperate” climates have given many tropical mountains and plateaus a deserved popularity, and the increasing settlement of the tropics by white men and women will constantly tend to bring such elevations into greater use. Under these conditions the usual law of the decrease of population with increase of altitude is locally reversed, at least up to a certain height. Mountains within the polar zones do not increase the habitable parts of the earth’s surface. Mountains within the tropics certainly give white men and women a larger area and more comfortable conditions of habitability. There is observable a tendency for the altitude of human settlements to increase from polar latitudes towards the equator. In the far north man lives close to sea-level; within and near the tropics there is often a large population at considerable altitudes, as in the Himalayas and on the Andean plateaus. In parts of South America at the present day (_e. g._, Colombia) the plateaus are the chief seat of the Spanish and Spanish-Indian population, and the lowlands are occupied by the negroes. The talk of removing the Brazilian capital from Rio de Janeiro to a more elevated location in the interior province of La Goyaz, and the government offices of the Italian colony of Eritrea from Massowa, on the Red Sea, to the high plateau of the Hinterland, shows the upward tendency of the white man in the tropics. On the other hand, the production of sugar-cane, coffee, and other valuable products will obviously lead more and more to the development of the lowlands under white control. To the greatest altitudes man is attracted by mineral wealth, and lives under very hard conditions. Some of the Tibetans live more or less underground, and melt ice in order to secure water. High mountains within the tropics show a vertical succession of climates from tropical at their base to eternal snow on their summits. A very striking illustration of this may be secured by a passenger who travels over the famous Oroya Railroad, in Peru. This road runs from sea-level to a height of 15,665 feet, and then descends again to about 12,000 feet. The first part of the journey is through fields of sugar-cane and cotton; at about 5000 feet a zone of fruit trees is passed through; at 10,500 feet there is a district famous for its potatoes, where little else is grown; above this, the altitude is so great as to preclude the growth of anything but grass. At the highest point reached, the snow lies on the mountain summits throughout the year, and the traveller may enjoy a snowstorm in the middle of summer (December-February). In the interior valley, farm produce is again seen growing. This whole succession of climates may be passed through in the short space of ten hours. Tropical mountains may thus produce temperate zone crops. In the deserts, mountains may be covered with forests and other vegetation, by reason of the rainfall which they provoke. Here man naturally settles, finding water and perhaps favourable conditions for agriculture. Such mountains become “islands” of denser population, as do the streams which run out from them to wither away in the desert. In Dar Fur, in the eastern Sudan, most of the inhabitants live in or near, and in close dependence upon, the Marra Mountains. Kilimanjaro, in equatorial Africa, rises as an island above the surrounding steppes, and is in the centre of a large population. At the southern foot of the Atlas Mountains there are three ethnological zones, from the nomadic desert-dwelling Tuareg to the Berber tribes scattered in the mountains, with a denser population in the strip of oasis between.

The permanent physiological effects of tropical mountain climates have not as yet been carefully studied. Junghuhn has noted an improvement in the physical condition of people who live at altitudes of 6000 to 6500 feet in Java; in Africa, the Zulus and Hovas have been instanced as furnishing an example of the strengthening influence of mountain climates, and other cases are cited of mountain tribes who rob, or rule over, lowland tribes. On the other hand, in Mexico, Jourdanet has described the anæmic condition, poor physical development, low birth-rate, and short lives of the inhabitants of the plateau of Anahuac, and Charnay noted the fact that the Indians who brought sulphur from Popocatepetl fell off in bodily vigour at an early age. Prescott, however, in his _Conquest of Mexico_, noted that the physical development of the Tlascalans on the plateau was better than that of the people of the lowlands. The enlarged lung-capacity of the inhabitants of the lofty _punas_ on the west coast of South America has naturally been attributed to the effect of the rarefied atmosphere. It is interesting to observe that it often happens that plateau and mountain peoples sicken and are unable to work when taken to sea-level, and the same thing is true of lowlanders who are taken to considerable altitudes. The Aymara Indians of Peru, when taken down to sea-level by the Spaniards, could not stand the change. Great difficulty has been found, as pointed out by Spence, in securing labourers on coffee plantations at altitudes of 4000 to 6000 feet in South America. Labourers from greater altitudes and from near sea-level alike become ill and unfit for work. Additional examples might be cited.

Special mention may be made here of a peculiar relation between climate and man on certain lofty tropical mountains, which are snow-capped, and which furnish a supply of snow or ice for refrigerating purposes in the towns below them. Thus in Ecuador, snow is carried to Quito from the upper slopes of Pichincha; to Riobamba and Ambato from the slopes of Chimborazo. Ambato used to supply its brewery with snow from the same mountain. Guayaquil was formerly supplied with ice in the same way. In Colombia, Popayan, in the department of Cauca, is also supplied with ice and snow from neighbouring mountains. In parts of Syria, also, snow, gathered in the mountains, is packed firmly in pits dug in the ground, and covered with straw and leaves. It is later sold. In Mexico, snow is carried from the summit of Colima to the towns on the hot plains below. Howarth notes the discovery of an “ice factory” in one of the highest valleys in Oajaca, in Mexico, at an altitude of 8000-9000 feet. In this case the active nocturnal cooling by radiation is the effective climatic factor at work. “The ground was covered with a vast number of shallow wooden troughs, which are filled at nightfall with water from the dividing stream, and during the nights of the winter months this becomes covered with a film of ice not more than one-eighth of an inch thick. In the morning this is removed and shovelled into holes in the ground, and covered up with earth, after which it consolidates and is cut out in blocks and sent down by mules, where there seems to be a ready market at all seasons.” On the high veldt the Boers keep their provisions by letting them cool outdoors at night. The peculiarly dry climate of the plateaus of the west coast of South America is due to the leeward position, west of the Cordilleras. The Incas preserved their dead by allowing them to mummify naturally in the dry, rare atmosphere.

The construction of railroads at high altitudes in the tropics, as on the west coast of South America, has been delayed and rendered expensive by mountain sickness, and by man’s decreased efficiency for work; by cloud-bursts, flooded rivers, and landslides. In the higher passes over the mountains, diurnal winds are sometimes met with of such velocity that travelling by day is impossible at certain seasons. Moritz Wagner has described the down-cast winds from the snowfields near Quito, which at certain times are of such violence as entirely to interrupt travel across the Chimborazo passes. Darwin and many others have noted the diurnal variation in the height of water in rivers fed by melting snow. Such streams are easiest to ford in the early morning, when the water is lowest.