SSS THE CANADIAN NATURALIST. 



These facts being premised, we see the cause of the difference 

 between our feeUngs and the height of the theimometer. 

 When the temperature of the atmosphere becomes colder, the 

 surrounding air abstracts the heat remaining in the mercury, 

 until the instrument and the atmosphere are exactly alike. 

 After this, it may blow a hurricane without affecting the 

 thermometer, for wind being nothing but motion communi- 

 cated to air, no more heat is abstracted, as it has already 

 been equalized. But a living body has a power o^ generatmg 

 heat, which passes in due course into the circumjacent air : 

 if the air be still and undisturbed, the portion immediately 

 around us becomes in some degree saturated, as it were, and 

 no longer abstracts the heat so fast ; perhaps not so fast as it 

 is generated, in which case we feel the sensation of warmth. 

 But let the air be put in motion, and the stratum of heated 

 air which enveloped the body is blown away, and new and 

 cold portions are every moment brought in contact with it, 

 which, abstracting the heat faster than it can be generated, 

 cause a sensation of cold that increases in proportion to the 

 force of the wind ; that is, to the rapidity with which fresh 

 particles are presented to the surface. This too explains the 

 use of clothes : they keep, but they do not make us warm : 

 they are made of substances which conduct heat slowly, and 

 so maintain a stratum of heated air around the body, parting 

 with the heat less readily than it is re-supplied. 



C. — I suppose the thickness of animals' fur in winter 

 answers the same purpose : I observe the horses and cattle 

 have their coats much thicker than in summer. 



F. — Yes; that is an admirable ordination of Divine 

 Providence, for the comfort of the inferior animals. No 

 sooner does winter approach, than the coat of our domestic 

 creatures (and I believe the wild ones too), which before 

 was thin and sleek, becomes thick, shaggy, and somewhat 

 erected, and partakes more of the nature of fur than of hair : 



