232 



GREENHOUSES 



This loss by friction cannot be disregarded. 

 Suppose, for example, it is desired to deliver 

 20 gallons per minute at a distance of 100 

 feet. By referring to the above table it will 

 be seen that if a 24-inch pipe were used, a 

 loss equal to a head of 115 feet would be 

 sustained, while if a i%-inch pipe were used 

 a loss of only 4.8 feet would be sustained. 

 It is economy to use pipe of generous size. 



Hydraulic Rams. The hydraulic ram is 

 a device which utilizes the force of water, 



Fig. 122. A simple type of hydraulic ram. a, intake 

 pipe; f, delivery pipe 



