144 



SMALL WATER SUPPLIES. 



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with by the filters. The filters would be better if 

 made in duplicate, because cleansing would not inter- 

 fere with the supply. 

 The outlet pipe is con- 

 nected to the clear-water 

 tank, the top of which 

 should be covered with 

 about 1 8 in. of earth in 

 order that the water 

 shall be cool in hot 

 weather, and should 

 have an overflow pipe 

 and wash-out, as shown 

 in detail in fig. 108. The 

 outlet from the filter 

 may be simply a rose on 

 the bell-mouth of the 



pipe (all outlets from 

 tanks should be by 

 means of a bell-mouth), 

 but a much better ar- 

 rangement, which is 

 strongly advised, is 



FIG. 1 08. 



shown in fig. no, in which the bell-mouth standpipe 

 can be raised or lowered by 

 the central screw and hand- 

 wheel, and so the depth of 

 water on the filter can be ad- 

 justed to give the desired rate 

 of filtration. The deeper the 

 water the greater the " head," 

 and consequently the faster the 

 flow in the filter. In the same way the distributing 



FIG. 109. 



