424 ON THE DIFFUSION OF HEAT 



and discharged from the circumference of the globe into unh- 

 mited space, we are lost in the magnitude of the result, and 

 are unable to acquire a just conception of the force of the ar- 

 gument, from the impossibility of contemplating clearly the 

 difficulty in all its extent. 



The difficulty, from the intensity of the heat which must be 

 assumed to exist, is not less great than that from its contimi- 

 anpe and waste. It is sufficiently apparent, when we consider 

 that the highest mountains of the globe run in extensive 

 chains, and are so connected, that they must have been form- 

 ed at one time, and that they are composed of materials which 

 a very intense heat does not fuse. But this is nothing com- 

 pared with the statement which must be made, in consequence 

 of the law, that the internal temperature is a decreasing one 

 from the interior to the circumference of the globe. 



If we can discover the rate of this decrease, by knowing the 

 temperature which exists at two distant points, we may of 

 course form some calculation of the intensity of the heat which 

 exists at the commencement of the series. Now this we have 

 the means of determining with considerable precision. At the 

 bottom of the sea, or within a short distance from it, the heat 

 from the interior must be at a degree of intensity sufficient to 

 produce mineral fusion and consolidation from the disintegra- 

 ted materials of a former land, which may be estimated from 

 our knowledge of the fusibility of these bodies. It is propa- 

 CTated from this onwards, with such a decrease that at the sur- 

 face, there is no sensible high temperature. Its diffi^ision from 

 the central regions to the bottom of the sea must of course have 

 been at a similar rate of diminution. If we were to calculate 

 the rate of progression, and compare it with the distances in 

 the two portions of space, — that from the central region to the 

 bottom of the sea, and that from the bottom of the sea to the 



surface 



