14 THE AURIFEROUS GRAVELS OF THE SIERRA NEVADA. 
the farmer to secure a bountiful harvest. In the winters from 1870 to 1873 
the annual rain-fall at Visalia was as follows: for the year 1870-71, 6.8 
inches; 1871-72, 10.3 inches; 1872-73, 7.2 inches. The crops of the 
year 1872 were abundant, those of the other years mentioned were failures. 
That the Great Valley on the whole is a dry region, is abundantly proved 
by the scantiness of its population, But there are here all possible facilities 
for artificial irrigation, with the aid of the copious streams coming down the 
slopes of the Sierra; although to utilize these in a suitable and economical 
way demands considerable capital and engineering skill, combined with in- 
telligent action on the part of the Legislature, backed up by the good will 
of a law-abiding people. 
The enumeration of the streams draining the western slope of the Sierra, 
as given in the preceding pages, indicates very clearly a considerable amount 
of precipitation in that region. Unfortunately there are no statistics giving 
the amount of rain and snow-fall for any considerable period at a sufficient 
number of stations to enable us to form any idea of the general average ; 
neither are there any measurements of the amount of water carried down in 
the different streams, which amount is not only very variable from month to 
month during the year, but also from year to year. That the precipitation 
is almost entirely during the winter months has been already stated ; that it 
increases with the elevation would also be inferred ; and, the southern por- 
tion of the Sierra being higher than the northern, it is probable that this 
increased elevation about compensates for the difference in latitude. If the 
Sierra opposite the Tulare Valley were no higher than it is from Sacramento 
north, we should almost certainly have no such large streams flowing down 
in that region as the Kern and King’s. If, moreover, the rain-fall were 
equally distributed throughout the year, instead of being, as it now is, limited 
to less than six months, the condition of things would be greatly changed, 
especially in relation to the mining interests of the Sierra. Almost the whole 
precipitation in the higher portions of the range is in the form of snow; and 
this usually remains in large part upon the surface, gradually melting away 
during the early spring and summer months, so that it forms a much 
more reliable source of supply than it would do if it had fallen chiefly as 
rain. The system of dams, reservoirs, and ditches by which the water of 
the High Sierra in the mining region is made available for the purposes of 
the miner, is very extensive, and a large amount of capital is invested in this 
form of improvements. The total quantity of the precipitated moisture in the 
