ANNUAL FALL OF RAIN ON THE DESERT. 129 



This, the climate of Fort Yuma, for nearly one year and a half, may be taken as representing 

 much of that of the desert. Certainly the latter has no greater rain fall, whatever less it may 

 be from increased proximity to the lofty sierra. 



In the Army Meteorological Kegister, (published Washington, 1855,) page 075, 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 



aad 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 2^ 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. 



nu 



