ANNUAL FALL OF RAIN ON THE DESERT. 
129 
This, the climate of Fort Yuma, for nearly one year and a half, may he taken as representing 
much of that of the desert. Certainly the latter has no greater rain fall, whatever less it may 
he from increased proximity to the lofty sierra. 
In the Army Meteorological Register, (published Washington, 1855,) page 675, a table is 
given of the mean monthly and annual fall of rain at Fort Yuma, of which the following is an 
abstract: 
1851, first 4 months...28 
1852, in summer.61 
1852, in autumn. 1.80 
1853, whole year. 1.78 
1854, whole year.„. 4.50 
and the mean given of the four years of observation is 3.24 inches of rain ; but, inasmuch as 
there were only two full years of observation, and one of those the quantity of rain was 
unusual, (1854,) it would appear as if the annual estimate given in the report was much too 
high. Two inches or 1\ inches would be a nearer approximation to the usual rain fall. 
Admitting, even, the large estimate, the quantity which would be soaked into the ground 
below the level of evaporation, to be drawn upon by an artesian well, is small. Further 
observations upon the subject of artesian borings may be found at the close of the report. 
Sectional views of the structure of the desert are given on plate VIII, figures 1 and 2. 
17 U 
