60 Temperature of the Terrestrial Glohe, 



heat, the temperature, at this time, is more than 2000 degrees, (3) 

 at a distance from the surface not exceeding the one hundredth 

 of the earth's radius ; while at the centre of our globe this tem- 

 perature surpasses 200,000 degrees, estimating it according to the 

 ordinary formulas which relate to solid, homogeneous bodies. (4) 

 But, although this explanation has been generally adopted, I have 

 shown, in my work, the difficulties which it presents, and which, 

 it appears to me, render it inadmissible. I believe I have there 

 shown in what manner the earth must have long since lost all 

 heat which it may primitively have had ; and subsequent reflec- 

 tion having confirmed me in this opinion, I shall present it here 

 with more precision and assurance than at first. 



The almost spherical form of the earth and planets, and their 

 depression at the poles of rotation, leave no room to doubt that 

 these bodies were originally in a fluid state. In the problem 

 having for its object the determination of the figure of these 

 bodies, geometricians consider them, in fact, as liquid masses, 

 composed of layers, each having the same density throughout all 

 its extent ; and the whole revolving round the same axis, of con- 

 stant direction, with a known and constant velocity. The den- 

 sity decreases, from one layer to another, in receding from the 

 centre towards the surface, either because these heterogeneous 

 layers have distinct densities, and are regarded as incompres- 

 sible, and that the most dense have sunk towards the centre 

 for the stability of the system ; or rather because, according to 

 the opinion of D. Bernouilli, subsequently revived by Thomas 

 Young, all these layers were formed of one homogeneous liquid, 

 susceptible of a certain degree of compression, and of which the 

 density consequently increases, in approaching the centre, by 

 reason of the pressure, also increasing, which the liquid exercises 

 upon itself In either case they suppose the entire mass of liquid, 



(3) Centigrade division is that employed by the author, throughout his work. 



(4) At page 428 of the author's Theorie MatUmatique de la Clialeur, he has the 

 following passage : 



" At the centre, and throughout the greater part of its mass, the materials of 

 which the earth is composed would then be in a state of incandescent gas ; yet so 

 condensed that their mean density would surpass, five times, that of water. To 

 contain these, at such a degree of condensation and of heat, an extraordinary force 

 would be necessary, of which we can form little idea ; and we may doubt if the 

 solidified layers of the globe would have thickness and cohesion sufficient to resist 

 the dilating power of these interiour, fluid»layers." 



