72 THE NATCRE AND TREATMENT OK 



as this simple plan of ventilation was adopted, the health of 

 the men improved. 



Vitiated air, under the above conditions, has an upward ten- 

 dency, still if we wish to diverge from the common mode, we 

 can give it a downward current, and thus effectually prevent all 

 expired air from again re-entering the pulmonary cells. The 

 act of expiration, through the nasal cavities of cattle, is in a 

 downward direction, and a current in this direction can be se- 

 cured when sufficient spaces near the ceiling are left open. 

 This plan was adopted by Mr. Bigelow, in the construction of 

 a barn and stable at West Cambridge. It is so constructed 

 that a current of pure air free from dust, is admitted under the 

 eaves all round the building, and there are loopholes in various 

 parts within a few feet of the floor ; these are furnished with 

 slides, which serve as regulators of the temperature of the at- 

 mosphere within. To insure a free downward current, it is 

 only necessary to open the slides, and if a still ptirer and cooler 

 atmosphere is desirable the doors may be opened also. A 

 warm atmosphere is secured by closing the slides and doors, 

 for then the current of air is interrupted. 



The only advantage, however, of this mode of ventilation 

 over the ordinary one which insures an upward current, is, the 

 air reaches the lungs uncontaminated by dust, or the exhalent 

 vapors of the body. 



In some stables in this city we observe a large hole in a 

 partition, or wall, right in the face and eyes of the animal. 

 This, in most cases, is objectionable, for, should the horse face 

 to the eastward, he has to contend against the acknowledged 

 depressing influence of an east wind, and facing otherways he 

 may encounter dust, vapor and rain. In view of all the facts 

 connected with the subject of ventilation, I contend that the 

 theory of an upward current is the most feasible and econom- 

 ical. This was the opinion of Sir Humphrey Davy, who, in a 

 letter to Lord Liverpool, in the year 1811, proposed to venti- 

 late the House of Lords. His plan was (and it is suggestive 

 to those about building new barns and stables), to construct 

 Jiues,iir)(\ admit fresh air by numerous openings in, or near, 'he 



