38o IRRIGATION FARMING. 



the supply, one- twenty -eighth to sixteen times the 

 hight of the supply, and so on. The manufadlurer of 

 Rife's ram gives the following rule for ascertaining 

 how many gallons may be delivered in an hour: Mul- 

 tiply the number of gallons the ram will receive 

 through the supply pipe a minute by the feet in fall. 

 Multiply the producfl by forty, then divide by the num- 

 ber of feet the water is to be elevated above the ram. 

 The result will be the number of gallons delivered in 

 an hour. 



Water-Motors. — In large streams of steady cur- 

 rent the Harvey water-motor, an outline of which is 



FIG. 88 — HARVEY WATER-MOTOR. 



given in Fig. 88, is considered quite a success in lifting 

 water for irrigation. By the use of wing dams in the 

 stream the force of the current operates diredlly upon 

 the wheel at the lower point of the dams, and in this 

 way power is created for running a centrifugal pump. 

 The wheel is a combination of an undershot and breast 

 wheel hung on a swinging frame, and is balanced by 

 a counterweight. Its gearing is a .sprocket-wheel, so 

 that it can be raised or lowered with the varying rise 

 or fall of the river wdthout any readjustment of gear- 



