10 
The Colorado Experiment Station 
entirely absent, no precipitation falling for three weeks or 
more. A general rain is not usual at this time of the year, the 
form being that of the thunder shower. These local stomis are 
often so frequent that several may occur over the same valley 
or region on the same afternoon. The western part of the State 
and high mountain regions receive most of their percipitation 
from the westerly winds from the Pacific ocean, while east of 
the mountains the supply obtained from the Gulf of Mexico 
becomes important. 
HEAVIEST PRECIPITATION DURING GROWING MONTHS 
The precipitation during the growing months of the year 
is about two-thirds of that for the entire year, and this is a 
very important factor, since this distribution makes our small 
supply more effective than it otherwise would be. In the crop 
season when we are subject to a long continued drouth and 
manv farmers are sometimes ruined and destruction is wide- 
%/ 
spread, one cannot fail to see that the state which would fail 
to develop its irrigation possibilities and reclaim its arid lands 
would be making a great mistake. From the mountain peaks, 
which collect the snows of winter, flow the streams which make 
crop production a certainty. The original source of all our 
lakes and streams is precipitation in the form of rain or snow. 
This is the original water supply. The guarantee to the irri¬ 
gator and farmer, to the irrigation enigneer and to the capital¬ 
ist who finances some of our large enterprises, is the informa¬ 
tion furnished by the rainfall observers over the State that 
there is a sufficient and steady water supply that can be de¬ 
pended upon, that we shall know intelligently the amount of 
water available for the use of crops, and that the hydraulic en¬ 
gineer may have data to calculate the supply tributary to the 
storage reservoirs or the streams from which their canals are 
taken. 
The normal barometer for the Station is 24.992 inches for 
the year. While the Station barometer has been moved two or 
three times, the change in elevation has been very slight and 
no correction has been applied for this. Only the correction 
for temperature has been applied. Our precipitation nearly 
always comes with a rising barometer. When the barometer 
is very low it is nearly always succeeded by wind. The pre¬ 
cipitation is preceded by any liarometer from the moderately 
low to the high. 
