[98] In many cases this decrease of salinity is probably due to a slow influx of fresh water from landward; but very often it cannot be thus explained.
[99] Journal für praktische Chemie, Vol. 98, p. 167.
[100] The normal composition of atmospheric air is given on [p. 16, chap. 2].
[101] A striking case in point is the regular wind which in summer blows through the “Golden Gate,” a gap in the Coast Range connecting the Pacific Ocean directly with the great interior valley of California, along the bays of San Francisco, San Pablo, and Suisun. The great interior valley and adjacent mountain slopes becoming intensely heated during the rainless summer, the ascending air is replaced by a steady indraught from the sea, which is bordered by a belt of cold water causing fogs along the coast. The fogs are quickly dispelled on reaching the edge of the valley near the middle of its length; whence steady breezes blow northward and southward, up the valleys of the Sacramento and San Joaquin respectively. These winds, popularly often, but erroneously, called trade-winds, are really “monsoons” similar in their origin to those of India, which, when coming from the sea cause rains, but when from the heated land itself are hot and dry; as in the case of the sirocco of Italy and North Africa, the terral of Spain and the northers of California.
[102] This designation is popularly and incorrectly applied to the comparatively limited, but very violent and destructive rotary storms or whirlwinds which originate locally on the heated plains of the Middle West of the United States, and are almost always accompanied by violent electric phenomena. These should properly be called tornadoes. At sea such whirlwinds give rise to waterspouts, in deserts to sand storms.
[103] “The Evolution of Climates”; by Marsden Manson, July, 1903; also Amer. Geologist, Aug.-Oct. 1897.
[104] See Rept. of the U. S. Commissioner of Agriculture for 1878, pp. 486-488; Bull. Nos. 16 and 42, Wyoming Expt. Station; Bull. No. 150 Calif. Expt. Station; Bull. No. 51, Nevada Expt. Station; South Dakota Station Bulletins Nos. 40, 69, 70, 74; Kansas Expt. Station, Bulletin No. 102; New Mexico Expt. Station, Bulletin No. 18; Montana Expt. Station, Bulletin No. 30; and others.
[105] “Rocks and Soils,” pp. 175-189.
[106] The early work of Schübler on soil physics, published at Leipzig in 1838 under the title of “Grundsätze der Agrikulturchemie” and now almost inaccessible outside of old libraries, is remarkable as having anticipated very definitely much that has since been brought forward and elaborated anew. He is really the father of agricultural physics.
[107] Bull. 22, Bureau of Soils, U. S. Dept. of Agriculture.