282 Ground Water, Wells and Farm Drainage. 



In Fig. 109 is represented a method used in measuring 

 the capacity of three Gould Sand Strainers, Nos. 50, 80 

 and 90, each 18 inches long, and the table below gives the 

 results secured. 



Table showing the rate of flow through three drive well points. 



The sand about the No. 50 strainer had a diameter of 

 .294 mm., that about the No. 80 .172 mm., and about the 

 No. 90 .085 mm. The table shows under these conditions 

 about 2 minutes of steady flow, under a pressure of 12 feet, 

 are required for the No. 50 strainer to supply sufficient 

 water for a single cow one day; 6 minutes for the No. 80 

 and more than 20 minutes for the No. 90 strainer. 



It would therefore be necessary to use a strainer 54 

 inches long in the No. 80 sand and one 17 feet long in the 

 No. 90 sand to supply the water obtained through the No. 

 50 strainer. 



350, Capacity of a Pump on a Sand Point and on an Open 

 Suction Pipe. When an ordinary pump is connected up in 

 the manner represented in Fig. 110, so as to draw water 

 through the sand point or through the open suction, the 

 capacity of the pump under the two conditions may be 

 very different. In the case of a two and a half inch cylinder 

 working on an 18 inch No. 50 sand strainer, or on the open 

 suction pipe as represented in the illustration, when 20 

 strokes would fill the pail from the open suction it required 



