76 HEALTH AND DISEASE 



For practical purposes the method of ventilation which has been 

 described, by the aid of openings at opposite sides of the building and at 

 the ridge, is the most simple, and, if properly arranged, the most effectual. 



A certain quantity of fresh air is absolutely indispensable for the 

 maintenance of life. A horse requires something over 15,000 cubic feet 

 of air per hour. But the question is not one of quantity only; there 

 can be no doubt at all that the exact amount of air which a horse 

 requires may be fully provided and yet be in such a condition as to 

 destroy the animal in a short time. 



The difficulty of ventilating a stable is increased by the objection which 

 the groom entertains to a current of cool air, which, however pure, will 

 make his horse's coat rough, or cause the warmly-clothed animals, which 

 have been habitually kept in hot stables, to shiver. This is a fact which 

 the groom will demonstrate without any difficulty, to ensure conviction in 

 the mind of his master, by opening a window behind one of his horses and 

 causing the animal to shiver forthwith as soon as the unaccustomed cool 

 current touches its skin. After this demonstration, with which stablemen are 

 perfectly familiar, the question is settled at once, without any further argu- 

 ment, and the owner of the animal, if not convinced, is at least silenced. 



The demonstration, although utterly fallacious, contains a valuable 

 suggestion, to the effect that the air of the stable should, by some means, 

 be properly regulated to a moderate temperature, so that the horses 

 should not be subjected to either hot or cold currents of air. 



If open fire-places with warm-air chambers are not provided, perhaps 

 the most satisfactory way is to heat the stables (or the air entering them) 

 by means of a low-pressure hot-water heating apparatus. 



Contamination Of Air. A very large number of causes of contami- 

 nation of air by physical and chemical agents are given by Dr. Parkes 

 in his work on practical hygiene. 



Among the mineral substances which are suspended in the atmos- 

 phere are particles of coal, sand, steel or other metal, and everything 

 which is included in the term dust, flocks of cotton, flax, hemp, all 

 of which may be either inhaled or swallowed. It is perfectly well known 

 that many trades are distinguished as unhealthy in consequence of the 

 inevitable mixture with the air of various products which are connected 

 with manufacturing processes. The effect of tlie air of mines appears 

 to be particularly deleterious to the health of the miners. It was stated 

 many years ago, by the chief medical officer of the Privy Council, that 

 30,000 miners in England break down prematurely every year from 

 pneumonia and bronchitis. At that time one exception only was given: 

 the colliers of Durham and Northumberland, where the mines were well 



