The Designing And Construction of Storage Reservoirs

ken all over the world varies, according to the locality, between zero and 338 in. or 28 ft. deep (which excessive amount was on one occasion registered in the hill district of Western India), it will be obvious how little ground there will be for assumption, in the examination of any district hitherto unexplored, with regard to the question of its rainfall. In the examination of any given country, however, there are certain phenomena connected with the rainfall that will be found of almost invariable acceptation, and may with advantage be borne in mind. The rainfall will, as a general rule, be greatest in those districts that are situated towards the point from which theprevailing winds blow. If Great Britain, for instance, be taken, the western districts will be found the most rainy. The very reverse, however, of this phenomena is noticed in the neighborhood of mountain ranges. If the wind prevails from one side rather than from the other, it is found that the greatest rainfall is on the leeward side of the range, and the probable solution of the matter is that the air, highly charged with moisture, is carried up the hills by the wind until it comes into a cold region of the atmosphere. Condensation of the watery vapor immediately takes place, and the result is a fall of rain on the side of the mountain rang" remote from the prevailing wind. To this cause may also be attributed the fact that the rainfall is always greatest in mountainous districts, while it by n...