ISO Oil Ike Diffusion of Heat 



must continue until that of the surface is such, that as much 

 caloric is discharged from it by radiation, as is received by the 

 solar rays, and it cannot proceed beyond this, Tb.e first con- 

 clusion necessarily follows, when it is proved that radiation is 

 the only mode by which caloric can escape from this planet. 

 The second conclusion is equally evident. Thus the tendency 

 13 to an equal and uniform temperature. How far this may be 

 from tiiat which at present exists, it is difiicult to determine. 

 If the increase of heat is accompanied with its more equal dif- 

 fusion, so as to establish nearly the same temperature over the 

 entire surface, it may not proceed much beyond that which now 

 prevails at the hotter parts of the earth; for at tiiis, when ex- 

 tended over the whole, the quantity of caloric radiated may be 

 c(|ual to that received. And even if it were to rise higher than 

 this; still, from gradual changes in the laws of organized matter, 

 or in the species of living beings, not greater than what seem to 

 have occurred in the past revolutions of the globe, the existing 

 temperature might be sufficiently compatible with the continuance, 

 of animated existence, and with an order not very different even 

 from that which now prevails. 



Different views have been presented of the relation of the tem- 

 perature of the globe to solar heat. Some have imagined that 

 the earth is in a state of progressive refrigeration ; and while it 

 \\as believed that the atmosphere could convey heat onwards 

 without limitation, this conclusion might be drawn. Others, 

 from considering merely the constant communication of solar 

 heat, have drawn the opposite conclusion, that its temperature 

 must increase, and this indefinitely. Wliile a more probable 

 opinion than either, founded on the apparent uniformity of na- 

 tural operations in those past periods to which any records reach, 

 is, that the temperature has always been the same, or nearly the 

 same, as that which now prevails. The view which follows from 

 the preceding observations is different from all these, and pre- 

 sents a more perfect arrangement. The temperature of the 

 globe must, from the mode in which heat is communicated to. 

 it, rise, and at the same time, as it advances, must become more 

 equal over the whole surface. And this rise has its limits ; there 

 cannot be either unlimited increase of heat, or indefinite refri- 

 geration ; but the final result will, be a state of permanence and 

 uniformity, the continuance of which is secured by the very cir- 

 cumstance, thatj if it is deviated from, the deviation must check 

 itself. 



No view has been presented in physical science of equal gran- 

 deur with that established from astronomical observations, that, 

 Hinid all the revolutions of the heavenly bodies, an order exists 

 whence the irregularities arising from their mutual actions do 



not 



