7 6 
Sir Benjamin Thompson's 
increasing its density even at the ex pence of its thickness. 
But this point will be further investigated hereafter. 
Bears, wolves, foxes, hares, and other like quadrupeds, in- 
habitants of cold countries, which do not often take the water, 
have their fur much thicker upon their backs than upon their 
bellies. The heated air occupying the interstices of the hairs 
of the animal tending naturally to rise upwards, in consequence 
of its increased elasticity, would escape with much greater ease 
from the backs of quadrupeds than from their bellies, had not 
Providence wisely guarded against this evil by increasing the 
obstructions in those parts, which entangle it and confine it 
to the body of the animal. And this, I think, amounts almost 
to a proof of the principles assumed relative to the manner in 
which heat is carried off by air, and the causes of the non-con- 
ducting power of air, or its apparent warmth, when, being 
combined with other bodies, it acts as a covering for confining 
heat. 
The snows which cover the surface of the earth in winter, 
in high latitudes, are doubtless designed by an all-provident 
Creator as a garment to defend it against the piercing winds 
from the polar regions, which prevail during the cold season. 
These winds, notwithstanding the vast tracts of continent 
over which they blow, retain their sharpness as long as the 
ground they pass over is covered with snow ; and it is not till, 
meeting with the ocean, they acquire, from a contact with its 
waters, the heat which the snows prevent their acquiring from 
the earth, that the edge of their coldness is taken off, and they 
gradually die away and are lost. 
The winds are always found to be much colder when the 
ground is covered with snow than when it is bare, and this 
