the Interior of the Earth. 277 • 



for 1* of increase ; their mean announces in general a more ra- 

 pid increase than that hitherto admitted. 4. Lastly,' in group- 

 ing by countries all the admissible results, I am led to a new 

 and important idea, which is, that the differences between the 

 results collected in the same place, do not depend solely upon 

 the imperfect nature of the experiments, but also upon a certain 

 irregularity in the distribution of the subterranean heat in dif- 

 ferent countries. 



In the second part of the memoir, M. Cordier gives a detailed 

 account of his own experiments on subterranean temperature, 

 made in coal-mines in France. These were conducted with 

 great care, and are apparently the most accurate hitherto made. 

 From these experiments, and those enumerated in the first part 

 of the memoir, he draws the following conclusions : — 



1. Our experiments fully confirm the existence of a subterra- 

 nean heat, which is peculiar to the terrestrial globe, does not de- 

 pend on the solar rays, and increases rapidly with the depthi^ 

 2. The increase of the subterranean heat does not follow the 

 same law over the whole earth ; it may be twice or three times 

 as much in one country as in another. 3. These differences are 

 not in constant relation, either with the latitudes or longitudes. 

 4. Lastly, The increase is certainly more rapid than has been 

 supposed ; it may go so high as a degree for every 15 or even 

 13 metres, in certain countries : provisorily the mean term can- 

 not be fixed at less than 25 metres. These important con- 

 clusions, M. Cordier remarks, fix the bases, at the same time 

 modifying them considerably, according to which the mathe- 

 matical theory of the dispersion of heat, in bodies of large di- 

 mensions, may be applied to the earth. They are in hai*mony 

 with the inferences derived from phenomena, of so very dii*- 

 ferent a nature, which have long afforded evidence of the inter- 

 nal incandescence of the earth. Brought into mutual connec- 

 tion, these different elements give rise to new combinations, and 

 to remarkable applications. In our opinion, there may be eli- 

 cited from them numerous inductions, calculated to throw light 

 on the most obscure, and, at the same time, the most essential 

 parts of geology. The following are the principal of these in- 

 ductions : 



JANUARY — MARCH 1828. T 



