838 THE CANADIAN NATURALIST. 
These facts being premised, we see the cause of the difference 
between our feelings and the height of the thermometer. 
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 of generating 
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. 
— 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 : 
