Capacity of Wells. 



283 



35, made at the same rate, to raise the same amount of 

 water, and the energy required to do the work was much 

 greater. The increased labor was due to the fact that the 

 water came in too slowly through the sand point to fill the 

 space behind the piston as rapidly as it was raised and a 

 vacuum was formed; into this the piston fell when the pres- 

 sure was released and the 

 water for only about half a 

 stroke could be secured. 



Sand strainers give a fair 

 well in very coarse material 

 where one of sufficient size 

 can be placed in a water- 

 bearing bed of sufficient 

 thickness, but generally they 

 can be depended upon for 

 only small amounts of 

 water. For wind-mill ser- 

 vice they are less satisfac- 

 tory because of the greater 

 power required to work the 

 pump. 



351. Depth of the Well 



An important feature of 

 every well, where the water 

 is intended for domestic or 

 stock use, is a sufficient 

 depth to prevent the quick 

 entrance of water from the 

 surface and to maintain a 

 constant low temperature. 

 This depth should usually 

 exceed 20 feet and even 

 where water is found nearer 

 the surface than this it is 

 better, if the water-bearing 



T^orla -mill norm if f\-f it +r* tr/\ Pl ' , 110 - Showing method of comparing 

 rmiT OI IT, TO gO the capacity of a pump working on 



30 or more feet and then 8and strainer and on an open weU - 



