AND ANIMAL HEAT. 195 



the relaxing atmosphere of overheated rooms. On 

 the contrary, comfortable warmth ought, in every 

 instance, to be drawn chiefly from its legitimate 

 sources, free respiration in a pure air, abundant out- 

 door exercise, vigorous digestion, and an actively 

 employed mind. If these conditions be observed, 

 little fire will be required to supply warmth to the 

 young. But if, as often happens, these be neg- 

 lected, and the generation of animal heat be thereby 

 reduced too low, we must either allow the mischief 

 to go on increasing, or afford adequate warmth from 

 without. It is in vain to think of rendering young 

 creatures hardy by subjecting them to the continued 

 influence of a depressing temperature. A few may 

 escape, but the majority will certainly suffer. 



In the heating of rooms and public halls, it is 

 proper to be on pur guard against rendering the air 

 too dry, a condition which is hurtful in causing too 

 rapid evaporation from the whole line of the air- 

 passages, as well as from the surface of the body, 

 and which is apt to produce considerable irritability 

 in the general system. On the Continent, where 

 stoves are much in use, a vessel containing water 

 is commonly placed on a sand-bath on th<? top, that 

 moisture may be generated quickly or slowly, ac- 

 cording to the degree of heat, and diffused through 

 the atmosphere. In such of our halls as are warmed 

 by heated air or stoves, some such plan ought to be 

 adopted. 



Having thus examined the chief conditions re- 

 quired for healthy respiration, it only remains far 

 us to throw out a few practical hints in regard to 

 what may be called the education of the lungs, or 

 the means by which their development may be 

 favoured, and their functions improved in tone and 

 extent. Most of these means have been already 

 noticed at some length, and the only important one 

 which still claims our attention is the exercise of th 

 lungs. 



