428 JOSEPH FOURIER. 
the annals of science, historians will not neglect to draw’ 
attention to this singular peculiarity: that the geometer 
to whom we owe the first certain demonstration of the 
existence of a heat independent of a solar influence in 
the interior of the earth, has annihilated the immense 
part which this primitive heat was made to play in the 
explanation of the phenomena of terrestrial tempera~- 
ture. 
Besides divesting the theory of climates of an error 
which occupied a prominent place in science, supported 
as it was by the imposing authority of Mairan, of Bailly, 
and of Buffon, Fourier is entitled to the merit of a still 
more striking achievement: he has introduced into this 
theory a consideration which hitherto had been totally 
neglected ; he has pointed out the influence exercised by 
the temperature of the celestial regions, amid which the 
hearth describes its immense orb around the sun. 
When we perceive, even under the equator, certain 
mountains covered with eternal snow, upon observing the 
rapid diminution of temperature which the strata of the 
atmosphere undergo during ascents in balloons, meteor- 
ologists have supposed, that in the regions wherein the 
extreme rarity of the air will always exclude the pres- 
ence of mankind, and that especially beyond the limits of 
the atmosphere, there ought to prevail a prodigious in- 
tensity of cold. It was not merely by hundreds, it was 
by thousands of degrees, that they had arbitrarily meas- 
ured it. But, as usual, the imagination (cette folie de la 
maison) had exceeded all reasonable limits. The hun- 
dreds, the tens of thousands of degrees, have dwindled 
down, after the rigorous researches of Fourier, to fifty or 
sixty degrees only. Fifty or sixty degrees beneath zero, 
such is the temperature which the radiation of heat from 
