AND THE UNITED STATES. 709 



summer, if we except a few weeks, nor polar in win- 

 ter, beyond a few days, and but seldom. Through- 

 out the greater part of that beautiful and fertile 

 country, the climate is strictly temperate, and far 

 better adapted to the support of a numerous, 

 wealthy, and highly civilized population, than 

 that of China, India, Persia, or any other portion 

 of Asia. 



Let us now examine how far, and in what way, 

 the stature, strength, form of the body, size and 

 configuration of the head, are modified by climate 

 or external temperature. In the first place, then, 

 it would seem to be a law of nature, that in man 

 and all the higher animals, respiration is augmented 

 in proportion as the surrounding temperature falls 

 below the point at which they are capable of main- 

 taining themselves at the natural standard, but di- 

 minished in proportion as the atmosphere rises above 

 that point, ceteris paribus. 



For example, it was ascertained by Dr. Craw- 

 ford, that when a guinea pig was taken from the 

 air of a room at the temperature of 61 and con- 

 fined in air surrounded with water at 55-J- for 

 forty-two minutes, it expired double the amount 

 of carbonic acid as when kept in air at 104 for 

 the same time. In another experiment he found 

 that on surrounding a guinea pig with air at 36, 

 it generated three times more carbonic acid in the 

 same time, than when made to breathe air at 102 



