5i8 



Reading-Course for Farmers. 



flow is too slow. Then a tank may be built in the barn or attic of the 

 house into which water may run regularly to be drawn out, irregularly, 

 at greater rates. If the flow at the time when the spring is lowest is 

 found to be as large or larger than necessary, it need only be dug out, 

 walled up, and covered. Wood will answer for this, but brick, stone or 

 concrete are more permanent. The relative elevation of the spring and 

 house must be carefully determined in order to make sure that the water 

 will flow at the highest point desired. It requires a certain force to keep 

 the water moving through a small pipe, and the following table shows 

 the number of feet necessary for this purpose alone. The spring would 



Fig. 317. — The reservoir, 2^00 feet away, that supplies, by gravity, the equipment 



shown in Figs. 315 and 316. 



have to be as much higher than the highest fixture is as shown in the 

 table : 



One-half inch pipe 



Flow in gallons per minute 0.5 i.o 2.0 4.0 7.0 10 



Head in feet lost by friction in each 100 feet of length. 4 7 17 54 140 124 



One-inch pipe 



Flow in gallons per minute i.o 



Head in feet lost by friction in each 100 feet of length 0.3 0.7 1.6 5.3 9.3 



This table shows thai it is importaiU to jjroportion the size of the 

 pipe used to the head available. For example, suppose the spring is 



