MUKPHv: irric;ation in western KANSAS. 119 



From Table II we see that at Dodge City the wind has a velocity 

 of 6 miles or more per hour for 8^ per cent of the time, and a veloc- 

 ity of 1 1 miles and upwards per hour for 54 per cent of the timf. It 

 is customary to assume that a wind-mill will run for ^^j } per cent of 

 the time, but from the above it is evident that a wind-mill properly 

 designed will work in this region a much larger per cent of the time. 



As regards the direction of the prevailing winds we have the follow- 

 ing table prepared from the U. S. Weather Bureau Report for 1891- 

 92, which gives the number of hours during the four irrigating 

 months that the prevailing direction of the wind was as indicated at 

 the head of each column at Dodge City. 



From this table we see that for these years the prevailing direction 

 was north or south 40 per cent of the time, N. K. or S. W. 18 per 

 cent af the time, and N. W. or S. K. 34 per cent of the time. These 

 results indicate that the proper direction for the axis of an overshot 

 wheel is nearly N. E. 



The Arkansas river is a mountain stream as distinguished from 

 other rivers which flow through and rise in the plains, which are 

 called i)lain rivers. It rises in the snow-covered mountains of cen- 

 tral Colorado. Much of its flood- flow is from its tributaries which 

 rise in the foot-hills and plains: the part of its water which is used 

 for irrigating comes mainly from the mountains. The precipitation 

 in the mountains at the upper end of the valley is much greater than 

 that in the valley in the r)Iains, and falling as snow is blown by the 

 wintls into the ravines and gulches filling them in places to a depth 

 of more than fifty feet. This slowly melting snow supplies most of 

 the water during July and August. The principal tributaries are the 

 Big Sandy from the north and the Purgatoire, Las Animas, Apishapa, 

 Huerfano and St. Charles from the south. These empty into the 

 river below Pueblo. 



Table lA' gives measurements of the flow of the river at a few 

 points and the drainage area above each point. 



The daily gaugings at Canon City for 1891 show that the river 

 began to rise about May ist, reached a maximum about June ist, 

 then gradually decreased till Aug. 6th, when the flow was about the 

 same as May 1st. 



