In securing constant and imperceptible atmos- 

 pheric currents, so that the air in a stable never 

 can become too highly charged with impurities, 

 the simplest system must be regarded as the best. 



The usual source for the egress and ingress of 

 air should be so disposed as to preclude the possi- 

 bility of being closed by wisps of hay and straw, 

 cloths, or boards, which are so often placed in win- 

 ter against every perceptible opening into a stable. 



Wide unprotected ventilating openings are ob- 

 jectionable, except so high above a horse as to pre- 

 vent direct draughts ; and even then they are often 

 objectionable, if so free as to interfere with regu- 

 lating the temperature of a stable. The theory 

 of admitting air by holes near the floor, and per- 

 mitting an escape near the ceiling, is plausible, 

 but in practice \ve find such air holes always to 

 favor draughts, and especially against the tender 

 skin of the horse's heels. 



Ventilating shafts, and a variety of systems to 

 produce air-currents through tubes in the ceiling, 

 fail, as a rule, in securing the desired object. We 

 have insisted on this point for a long time, and 

 have . recently been supported in our views by a 

 report on the ventilation of cavalry stables. The 

 commissioners state " When the shafts are pro- 

 perly made, the action of the law of difference of 

 temperature, occasions a more or less constant 



