170 COVERING OF ANIMALS. 



the naked eye, through which a thin, watery liquid is 

 continually issuing, called the sweat, when percepti- 

 ble to the senses ; — at other times, the insensible 

 perspiration. If our sight was sufficiently keen, we 

 should see every person in health, surrounded with 

 a cloud of vapor. 



B. But still, how is this to prevent the body from 

 being overheated ? 



A. Upon a very simple principle, which is here 

 beautifully introduced. If we wet our ringer and 

 hold it in the air, we are sensible of an immediate 

 coolness in the finger. It is because the heat escapes 

 with the moisture, as the finger dries ; and the 

 quicker we dry the finger by waving it in the air, the 

 greater the coolness produced. The constant evapora- 

 tion or drying up of the perspiration of the skin has the 

 same effect ; — and hence the danger of sitting by an 

 open window, or in a current of air, when the per- 

 spiration is free. 



IB. This brings into view a new kindness of 

 Providence, that the more the body is heated by 

 weather or exercise, the more moisture is thrown out 

 upon the surface. The fire becomes its own extin- 

 guisher. We now understand also how those marvel- 

 lous accounts may all be true, of persons setting in 

 hot ovens without being burned. The profuse perspi- 

 ration prevents the effects of the heat. 



T. Do we discover any striking varieties in the 

 coverings of different animals ? 



A. "The human animal is the only one which is 

 naked, and the only one which can clothe itself. 



