JOvSEPH FOURIEE. 167 



Marian, Bailly, and Buifon, what lias our colleague found? A thirtieth 

 of a degree ; not more. 



The surface of the eartb, which originally was perhaps incandescent, 

 has cooled then in the course of ages so as hardly to preserve any 

 sensible trace of its primitive heat. However, at great depths, the 

 original heat is still enormous. Time will alter sensibly the internal 

 temperature ; but at the surface (and the phenomena of the surface can 

 aloiie modify or compromise the existence of living beings) all the 

 changes are almost accomplished. The frightful freezing of the earth, 

 the epoch of which Bulfon fixed at the instant when the central heat 

 would be totally dissipated, is then a pure dream. At the surface, the 

 earth is no longer impregnated except by the solar heat. So long as 

 the sun shall continue to preserve the same brigiitness, mankind will 

 find, from j^ole to pole, under each latitude, the climates which have 

 permitted them to live and to establish their residence. These, gentle- 

 men, are great, magnificent results. While recording them in the annals 

 of science, historians will not neglect to draw attention to this singular 

 j)eculiarity — that the geometer, to whom we owe the first certain demon- 

 stration of the existence of a heat independent of a solar influence in 

 the interior of the earth, has annihilated the immense part which this 

 l^rimitive heat was made to play in the explanation of the phenomena 

 of terrestial temperature. 



Besides divesting the theory of climates of an error which occupied a 

 prominent place in science, sujiported as it was by the imposing authority 

 of JMarian, of Bailly, and of Buflbn, 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 earth 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, 

 meteorologists have supposed that, in the regions wherein the extreme 

 rarity of the air will always exclude the presence of mankind, and that 

 especially beyond the limits of the atmosphere, there ought to prevail a 

 prodigious intensity of cold. It ^^'as not merely by hundreds, it was by 

 thousands of degrees, that they had arbitrarily measured it. But, as 

 usual, the imagination {cettefolie de la maison) had exceeded all reason- 

 able limits. The hundreds, the tens of thousands of degrees, have 

 dwindled down, after the rigorous researches of Fourier, to fifty or six;ty 

 degrees onlj-. Fifty to sixty degrees hcncath zero, such is the temper- 

 ature which the radiation of heat from the stars has established in the 

 regions furrowed indefinitely by the planets of our system. 



You recollect, gentlemen, with what delight Fourier used to converse 

 upon this subject. You know well that he thought himself sure of 

 having assigned the temperature of space within eight or ten degrees. 



