82 HEALTH AND DISEASE 



DRAINAGE 



In applying the principles of drainage to the habitations of the domestic 

 animals there are on the whole fewer difficulties to be overcome than in the 

 case of the human being. The effectual removal of solid and liquid excreta 

 is the object sought in all cases; but while the sanitarian, in dealing with 

 houses inhabited by human beings, is compelled to devise some method, 

 not only for the removal of excreta, but also for destruction or disposal of 

 it in such a manner that no nuisance may arise from its accumulation, the 

 solid and liquid excreta of the horse have a commercial value as fertilizing 

 material or manure, and are not therefore destroyed or deliberately allowed 

 to pollute rivers and water- courses, as it pays better to store them for use. 

 The difficulty in dealing effectually with solid and liquid excreta from the 

 lower animals arises from the fact that the quantity voided by the larger 

 quadrupeds is considerable, and, in respect of the solid manure, the act of 

 excretion or expulsion is frequently performed, rendering it almost impos- 

 sible to keep a large stable in a condition of even moderate cleanliness. 



Emanations from animal excreta are not likely to contaminate the air 

 of a stable or cow-shed to any serious extent while in a fresh state, but 

 both solids and fluids rapidly undergo decomposition, the result of which is 

 to set free certain compounds of hydrogen and other gases, which are not 

 only offensive, but, some of them at least, poisonous — sulphuretted hydrogen, 

 for example, arising from the solid excreta chiefly. 



Urine very quickly changes its state, and sets free a quantity of am- 

 monia in a gaseous condition. Ammoniacal gas has an intensely pungent 

 character, and causes severe irritation of the mucous membranes of the eyes 

 and nostrils, to an extent which can only be appreciated by those who have 

 entered a badly ventilated or un ventilated stable in which a large number 

 of horses are habitually kept, or the holds of cattle-ships immediately after 

 the cargo has been landed. A little experience of this kind should suffice 

 to convince a horse-keeper of the great importance of making proper 

 arrangements for the removal of excreta from the stable at once, no matter 

 how often it may be necessary, to some convenient place of storage at a 

 distance from the stable, so that the gases from the manure-heap may not 

 be driven by winds into the stable or shed. 



Stables in large towns are generally situated in rows in a long mews, 

 and the dirty straw, with the excreta, often form a conical heap outside the 

 stable door. Usually the sanitary authorities insist on the removal of the 

 heaps at short intervals, so that very little opportunity is allowed for putre- 

 factive fermentation to go on ; but the same system is often adopted in the 

 open country, where there is ample space for proper storage. The real 



