62 



VETERINARY HYGIENE 



is formed by a lip which dips down two inches or so into the water 

 below the outlet level. The lip should be so placed as to offer no 

 obstruction to the removal of sediment. Many gullies are provided 

 with a bucket to facilitate the removal of the solids. These traps are 

 placed wherever a stable drain enters a common drain and in other 

 places where there is likelihood of much sediment being carried by 

 surface water, such as in the surface channels at road sides. 



Since the professed object of any system of drainage is to 

 remove as speedily and as safely as possible all decaying organic 



FIG. 24. Dean's Gully Trap FIG. 25. Road Gully Trap, 



with a round bottom and 

 sediment pan. 



matter, it will be obvious that any gully trap that is not self-cleans- 

 ing, and this none of them can be, can hardly be regarded as a 

 " sanitary " fitting. The filth that collects in them usually gets 

 leave to stay there until the trap gets choked and attention is drawn 

 to the fact by the overflow of foul-smelling fluid, at least that is 

 the case with most stable traps though street gullies receive more 

 attention. The collection of decaying organic matter gradually 

 decomposes, giving off in the process gases which pass freely into 

 the air, not uncommonly immediately outside a stable door or 

 directly under a stable air inlet. 



Figure 26 shows a type of gully now in common use. It is 

 fitted with a deep bucket, which is perforated at the top for 

 an overflow into the trap proper and which has an inlet fitted with 

 a deep lip so constructed as to guide solids into the bucket and 

 which, at the same time, acts as a seal of a sort by dipping into 

 the liquid in the bucket. This particular type of gully possesses 

 no real advantage over the more simple, and it is certainly more 

 difficult to clean. 



The evils of the street gully have been pointed out by Dr. J. T. 



