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 finger 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. 



B. 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 Jire 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. 



