60 



VETERINARY HYGIENE 



purpose and is, therefore, completely changed with a moderate 

 flushing. Buchan's disconnecting or intercepting trap, or some 

 modification of it, is in general use to-day for the purpose of com- 

 pletely cutting off the sewer from the house drain. The inlet side 

 of a disconnecting syphon trap is provided with an opening to allow 

 of the free passage of air into both trap and piping. This keeps 

 the air in the pipe fresh and at atmospheric pressure, and at once 

 disconnects the house pipes from the sewer pipes. This air inlet 

 communicates with the air at or about ground level by means of 

 a length of suitable pipe. At the outlet end of the trap there should 

 be a hand-hole fitted with a lid well luted down with clay or cement 

 in the case of fireclay fittings, or luted with prepared felt and bolted 



down in iron fittings. 

 This hole provides 

 access in case of 

 chokage, and through 

 it clearing rods can 

 be passed to move on 

 the obstruction. 



With some traps 

 the hand-hole is ex- 

 tended to form a 

 raking - arm which 

 makes it more acces- 

 sible; this is shown 

 in figure 21. The 

 hand-hole may also, 

 if required, be used as an outlet for sewer gas, in which case the 

 pipe connected with it is carried above the level of the eaves and 

 well clear of windows. 



When a disconnecting trap of Buchan's or similar design is 

 made in one piece there is often difficulty in making a good con- 

 nection with the pipes at either end, owing to the angle at w r hich 

 they have to meet the trap. To overcome this the trap is con- 

 veniently made in two sections, a head-piece fitted with the inlet 

 and ventilation hole and the syphon trap itself. Thus trap and 

 head-piece may be pivoted in any direction required, and perfect 

 jointing can then be ensured. 



With a house drainage system all the excreta, both soil and waste 

 water, is conveyed away as useless and dangerous material to be 

 got rid of as expeditiously and as economically as possible, the 

 chief object in view being to safeguard the health of the populace. 

 With animals, on the other hand, both liquid and solid excreta 



FIG. 21. Disconnecting Trap with clearing 

 arm extension. 



