466 ON IMPRESSIONS OF COLD 
come a desert. The tropical countries. would be burnt up by 
unmitigated fervour ; while eternal frost, usurping the polar re- 
gions, would extend its dominion within the temperate zone. 
The little portion of the surface left to animation, would be 
blasted by the excessive inequalities of the seasons, and of the 
diurnal vicissitudes. The sultriest days would have invariably 
closed in nights of pinching cold, and this mild climate would 
have exhibited all the rigours of a Canadian winter, succeeded 
by the fervid heat of an oppressive summer. 
The opposite condition leads to results still more appalling. 
If heat encountered no impediment. in its internal motions, 
but diffused itself with almost instantaneous effect, it might 
amuse the fancy to contemplate for a moment the vast and 
tremendous consequences. An uniform and unyarying tem- 
perature would then pervade the globe ; no distinction of cli- 
mate would exist, no vicissitude of seasons, and no grateful 
alternation of day and night. The azure vault of heaven, per- 
tually serene and cloudless, would lose all its animated charms. 
If snow and hail would be unknown, so would likewise the re- 
freshing influence of rain and dews. The face of the earth 
would present a monotonous picture of sterility ; no verdure 
to relieve the eye, —no vegetation,—and no sustenance for ani- 
mals. All the springs of life would be locked up. The bene- 
ficial effects,—the very existence, of artificial heat, would for 
ever have been concealed; since the instant this was genera- 
ted, it would spread and ingulf itself in the general mass. 
It is, therefore, an important study, to discriminate the cir- 
cumstances which modify and regulate the distribution of 
heat among bodies. ‘Towards a correct knowledge of the 
subject, very considerable advances have been made, though 
some vague and crude notions are still suffered to prevail. To 
comprehend rightly the observations and reasonings contained 
in 
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