breaks, or in the case of protection against frost by the use of "smudges," or screens, or fires, or by erecting lightning rods to guard buildings against the danger of being struck. Man can not make it rain; nor can he prevent hail from falling, nor can he change his climate by planting forests. 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.
Some Old Views Regarding the Effects of Climate on Man.—It is, however, easy to go too far in calling upon climate to explain certain phenomena which we may otherwise find it difficult to account for. This was the mistake formerly made by many writers on this subject. The broad generalizations of Montesquieu, Voltaire, 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. We must remember that we are dealing here with large, 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 can not be definitely and satisfactorily solved to-day—or to-morrow.
Climate and Habitability.—Climate determines where, as well as how, man shall live. It classifies the earth's surface for us into the socalled 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 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 hardest and where all life has to be especially
