CLIMATE IN SOME OF ITS RELATIONS TO MAN 249 



" the doctor." The location of dwellings is often determined by the 

 exposure of a site to this wind. For this reason, many native villages 

 are placed as near the sea as possible. The houses of well-to-do for- 

 eigners often occupy the healthiest and most desirable locations, where 

 the sea breeze has a free entrance, while the poorer native classes live 

 in lower, less exposed, and less desirable places. A social stratification 

 is thus determined by the sea breeze. In our own latitudes, exposure 

 to sunshine is very important, as is well known, in determining house 

 sites. Lugeon's study of one of the principal valleys between Mar- 

 tigny and the Ehone Glacier, has brought out some interesting facts in 

 this connection. In this district the villages, with one or two excep- 

 tions, are on the sunny side. In fact, a distinction of classes results 

 from this difference. There is developed what may be called an " aris- 

 tocracy of the sun." The people on the sunny side are more prosperous 

 and better educated, and look with some contempt upon the people on 

 the shady side. 



The trades, except where they blow onto windward coasts, or over 

 mountains, are dry winds. On the lowlands swept over by the trades, 

 beyond the polar limits of the equatorial rain belt (roughly between 

 latitudes 20° and 30°) are most of the great deserts of the world. The 

 interior of Africa has been out of contact with the civilized world 

 largely because of the deserts to the north and south of it. Goods and 

 passengers go around rather than across these deserts. In the desert, 

 population gathers in oases, as on islands. Here the trails followed by 

 the caravans converge like sailing routes at sea. There are small 

 Arabian towns, built at oases, 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. 

 The overflow of the Nile results from the rainfall on the moun- 

 tains of Abyssinia during the northward migration of the belt of equa- 

 torial rains; and one of the most difficult problems in the construction 

 of the Panama Canal, viz., the control of the floods of the Chagres 

 River, is due to a similar cause. 



The monsoons, reference to which was made a moment ago, are a 

 special development of the general trade wind system. Monsoon re- 

 gions have summer rainfall, and these rains are particularly heavy 

 where the winds have to climb over high land. Thus, in India, the 

 precipitation is heaviest at the head of the Bay of Bengal, where in the 

 Khasi Hills, at a height of a little less than a mile above sea level, the 

 rainfall averages between 35 and 40 feet a year. This is about ten to 

 twelve times as much as the rainfall of New York City, and all this 

 water falls in less than six months. Truly, at that place, " it never 

 rains but it pours." In certain parts of India stores of provisions are 

 laid in before the rains begin, the preparations being similar to those 

 made on board a vessel bound on a long voyage. Special mention may 



