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 

 Mearth 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 



