262 



Of the Propagation of Heat 



In cooling the Thermometer | 



from . . . 200° to iSo° j 



from 180 to 160 



160 to 140 



120 



100 



80 



60 



40 



Total times in coojing from | 

 200° to 40° . . . . j 



Times employed in cooling ~) 

 the instrument 80 degrees, ^ 

 viz. from 160° to 80° . J 



The results of these experiments are extremely inter- 

 esting. They not only make us acquainted with a new 

 and very curious fact, namely, that feathers and other 

 like substances, which, in air, are known to form very 

 warm covering for confining Heat, not only serve the 

 same purpose in water, but that their effect in prevent- 

 ing the passage of Heat is even greater in water than in 

 air. 



This discovery, if I do not deceive myself, throws a 

 very broad light over some of the most interesting parts 

 of the economy of Nature, and gives us much satisfac- 

 tory information respecting the final causes of manyphse- 

 nomena which have hitherto been little understood. 



