Page:Popular Science Monthly Volume 17.djvu/16

6 believe, in accord with the facts. The polar tribes are known to be yellow. Among them, more frequently than elsewhere, according to Quatrefages, occur cases of dry, rough skins. This I take to be a result of the thickness of the cuticle, just as, on the older parts of a tree, the roughness of the bark is a consequence of its thickness.

It is well known that the climate of Europe, where white men most abound, is more influenced by the sea than that of any other continent. With the inconsiderable exception of the Caspian and Arctic regions, where yellow men occur, it may all be said to be kept moist by breezes from warm tracts of water. The fairest members of the human family are found in the humid lands about the North and Baltic Seas, where the influence of the Gulf Stream is most felt, and where a temperate climate extends farther from the equator than elsewhere on the face of the globe. When we proceed eastward from the Baltic, the complexions gradually darken as the increasing range of the thermometer indicates increasing dryness. Moscow, Kazan, and Tomsk are all near the fifty-sixth parallel of north latitude. The difference between the temperatures of the warmest and coldest months at these places is respectively 53°, 61°, and 69° Fahr. At Moscow, the population consists of fair- and dark-haired whites. About Kazan, though there are still fair and dark whites, there are also yellow men. At Tomsk the entire native population belong to the yellow race.

That the climate of the whole of Asia, from the Hindoo-Koosh and Himalaya Mountains northward, may be considered dry, is shown by the extensive deserts and the great range of temperature in the countries where sufficient rain falls to render agriculture possible. For instance, in China and Japan the range of the thermometer is somewhat greater than in corresponding latitudes in the eastern United States. The entire population of this vast area is yellow, with insignificant exceptions on its western border.

The greater part of North America corresponds in climate with central and eastern Asia. But the meteorological phenomena of the coast of British Columbia and Alaska are similar to those of the northwest of Europe. Warm winds from the Pacific keep the temperature high and the air moist; but, owing to the configuration of the coast and the direction of the mountain-ranges, their influence does not extend far inland. The immense difference between the climatic conditions of the eastern and western coasts of America may be illustrated by comparing the temperatures of Sitka (57° 3' N. L.) and Quebec (46° 49' N. L.). Though the latter is more than ten degrees farther south, its mean annual temperature is two degrees less, and, while the difference between the means of the warmest and coldest months is fifty-seven degrees at Quebec, it is only twenty-five at Sitka.

It is a fact which strikingly corroborates the theory advanced in this paper, that it is precisely in the northwestern part of this