SANITATION 



61 



an- valuable assets, at any rate to the farmer, and according to the 



iiM.- made of excremental products the success of farming to a large 



extent depends. In towns the 

 t of transport is often greater 



than the value of the manure, un- 

 less the supply is both large and 



constant. Not only is the mone- 

 tary value of the manure less but 



its danger from a hygienic point 



of view is far greater, and it must 



be remembered that stored horse 



manure is a favourite breeding 



ground for flies. Consequently 



all animal excreta in populous 



places must be considered merely 



as waste products much in the 



same light as human excreta. 

 While the urine of animals 



can pass down the drains into the 



common sewer when the animals 



are stabled in a town, the nature 



and bulk of the so-called solid 



portion is such that any attempt 



to remove it by the common 



channel would speedily end in 



disaster. It is therefore obvious that special traps must be used in 



connection with animal habitations 

 which will let the fluid pass into the 

 drain and at the same time hold back 

 the more solid portion. For this pur- 

 pose Gully Traps are placed at the in- 

 let of the drains; they are specially 

 designed to catch and retain any solid 

 matter that may be washed into them 

 and which, but for their presence, 

 would be carried into the drain. 

 Their usual form is that of a some- 

 what deep rectangular box with an in- 

 let at the top provided with a grating 

 which is placed at the surface level. 

 The invert of the outlet is usually 



about two-thirds the distance from 

 Fie. 23. Dean s Gully Trap with 



a flat bottom and sediment pan. the bottom of the trap, and the seal 



FIG. 22. Combination of Syphon 

 Trap, adaptable inlet piece, and 

 ventilating shaft. 



