|Fort Churchill, Nev | 7.43 | 52 | 75 | 4,284|39 17| 3 9 | |Camp Floyd, Utah | 7.33 | 49 | 74 | 4,867|40 16| 2 6 | | +-------+------+-----+------+-----+---------+ | Means | 13.80 | 45 | 70 | 5,300|40 05| -- | +-------------------------+-------+------+-----+------+-----+---------+ Two of the stations, Salt Lake City and Camp Douglas, lie within the zone of climate modified by Great Salt Lake, and a brief inspection of the table will show how greatly their climate is influenced. As a general rule, the localities of greatest precipitation in the Rocky Mountain Region have so great altitude that their summer temperature does not permit agriculture, but Salt Lake City, with an altitude 1,000 feet below the average of the 24 stations, and a temperature 4° above the average, has a rainfall 11 inches greater than the average; and Camp Douglas, 3° warmer than the average and 250 feet lower, has a rainfall 5 inches greater. If the two stations are compared with those which lie nearest them, the contrast is still more striking. Camp Halleck, 130 miles west of the lake, and 600 feet higher than Camp Douglas, has a rainfall of 11 inches only. Fort Bridger, 90 miles east of the lake and 1,600 feet higher than Camp Douglas, has a rainfall of 8 inches. Camp Floyd, 30 miles south of the lake and sheltered from its influence by mountains, receives only 7¹⁄₃ inches. But Salt Lake City and Camp Douglas, lying between the lake and the Wasatch Range, record respectively 24.8 and 18.8 inches. In fine, it appears that the climate of the eastern shore of Great Salt Lake is decidedly exceptional and approximates in humidity to that of Central Kansas. The fact that it admits of dry farming gives no warrant for the belief that large areas in the Arid Region can be cultivated without irrigation, but serves rather to confirm the conclusion that the limit to remunerative dry farming is practically drawn by the isohyetal line of 22 inches. Even in this most favored district the yield is so small that it can be doubled by irrigation, and eventually water ditches will be carried to nearly all the land that has yet been plowed. CHAPTER V. CERTAIN IMPORTANT QUESTIONS RELATING TO IRRIGABLE LANDS. THE UNIT OF WATER USED IN IRRIGATION.