THE HORSE HYGIENE AND SANITARY CONDITIONS. 643 



this device the shaft is always closed and no foul air from the 

 stables comes into the barn or settles among the stored-up hay, 

 oats, or straw. This ventilating shaft is promotive of health 

 among the animals and cleanliness in the barn and feed rooms. 

 The expense of such shafts is trifling when compared with the 

 gains in a sanitary point of view. 



Sub-ventilators. As warmth in the horse stable, cattle 

 barn, and pig pen is economical, being a saving of fuel in the form 

 of feed to keep up animal heat it is the part of sanitary science 

 to devise means for securing warmth of stables arid keeping the 

 air pure as nearly as possible. Since carbonic acid gas is heavier 

 than common air, no system of ventilation is complete that does 

 not provide for change of air at the floor of the building. Air 

 brought into the stable through underground tubes gives warmer 

 air and causes the removal of heavier air and impure gases so 

 they can not accumulate to an injurious degree. The law 

 of diffusion of gases causes the carbonic acid gas to be thus 

 lifted with the nitrogen and oxygen and hydrogen and passed to 

 the outer air by the ventilators. The system of supplying air 

 of a higher temperature than outer air to the closely built 

 stables is economical and health-giving. 



Prof. Cook, of Lansing, Mich., has successfully adopted sub- 

 earth ventilation for the College Apiary. The air entering by 

 the sub-earth tubes or tiles is many degrees warmer than the 

 surface air. By this means we can have a comfortable tempera- 

 ture and a pure atmosphere in our stables at a very small out- 

 lay. The cost of repairs of these devices is absolutely nothing, 

 yet the benefits derived are very great. 



A Vitiated Atmosphere is the source of more loss by 

 disease to the farmers who have horses and cattle in close stables, 

 and sheep and swine in illy ventilated pens, and poultry in 

 noisome houses, than all other causes combined. The air that 

 is expired from the lungs differs from that which was intro- 

 duced into them not merely in the altered proportions of its 

 oxygen, nitrogen and carbonic acid, but also in a large addition 

 to its watery vapor, which from the lungs of a man ranges 

 between 16 to 20 oz. a day. 



