428 CONDITIONS AFFECTING AGRICULTURAL PROSPERITY/ 



than on the eastern flank of the Sierra, where the rain-fall is very 

 limited. The same law is well known along the southernmost part of 

 Lower California. 



At the head of Sacramento Yalley, in latitude 41, where the 

 Coast Range of mountains crowds upon the Sierra Nevada, the 

 clouds are banked up heavily, and it is safe to say that four times, 

 and in some seasons perhaps ten times as much rain falls at Shasta 

 as in the region of Kern Lake, at the southwestern extremity of the 

 valley. This latter section is the driest region in the whole valley, 

 and probably only half the rain falls there that falls about the vicin 

 ity of Baker sfield. 



On the Coast Eange of mountains, snow very rarely falls, and 

 never lies over twenty-four hours; but on the Sierra Nevada, it falls 

 to a depth of sixty or seventy feet (observations at Summit station, 

 in 1S66- G7), and lies throughout the winter with an average depth 

 of fourteen feet. This snow forms a great natural storehouse of 

 water; it supplies the streams throughout the year. If the greater 

 body of it is melted during the winter by warm rains, it causes dis 

 astrous floods; but in ordinary seasons the main body of it is melted 

 about June, and causes the summer rise in the rivers. 



The law of the greater precipitation of rain upon the western 

 flanks of the mountains is well exhibited in the number, size and 

 volume of the streams which have their sources in these mountain 

 ranges. The streams of the west, or seaward flank of the peninsula 

 of San Francisco and of the Coast Range northward, are greater 

 than those on the eastern flank, and especially marked is this in the 

 case of the Sierra Nevada, where it may be also noted that the 

 streams of the west flank exceed in aggregate volume those of both 

 flanks of the Coast Range. 



The figures to establish this well-known law are not produced in 

 this place, as they will be used in the remarks upon the unequal fall 

 of rain over the country. 



The average yearly rain-fall over the basin of the Great Yalley, is 

 sufficient to insure good crops annually. 



This proposition embraces two vital questions: 1st. &quot;What amount 

 of rain-fall, if properly distributed, will insure a crop ? 2d. What 

 amount of rain-fall is there over the entire basin of the Great Yal 

 ley? Fortunately, a good practical example is at hand. During the 

 rainy seasons of 1870-71, 1871-72, 1872-73, a record of the rain-fall 

 at Yisalia was kept by Dr. James W. Blake, and is both instructive 

 and reliable. In 1870-71, the total rain-fall was about 6.8 inches; 

 in 1871-2, 10.3 inches; in 1872-3, 7.2 inches. In the first and third 

 of these years, the crops were failures; in the second the harvest 

 was an abundant one. In 1872-3, the distribution was very equable 

 and adequate to the end of February; after that, only one quarter 

 of an inch fell upon one day in March and one in April, and the 

 crops were virtually lost. The critical period in the growing crops 

 appears in this, as in other districts, to be about the middle or end 

 of February, when the grain is several inches high, and another 

 rain-fall of one or two inches would give good crops, while a cessa 

 tion of rain leaves them blighted. The rain-fall at Yisalia, 1871-72, 

 when a full crop was secured, was as follows: 



