on Subterraftean Temperature. 45 



We shall now sum up the consequences that may be drawn 

 from the first part of our investigation. 



1^^, If we except a certain number of observations as pre- 

 senting too much uncertainty, all the rest announce in a more 

 or less positive manner, that there exists a remarkable increase 

 of temperature proceeding from the surface of the earth towards 

 the interior. It was therefore with reason that this increase 

 was admitted. 



2rf, The results obtained at the Observatory of Paris are the 

 only ones from which a numerical expression of the law which 

 this increase follows may be deduced with certainty. This ex- 

 pression carries lo 51 feet, the depth which corresponds to the 

 increase of 1° Fahr. of subterranean heat, and, as we cursorily 

 mention, there results from this that the temperature of boiling 

 water would only be 8212 feet, or one and a-half miles Eng- 

 lish, under Paris). 



3^/, Of all the other results, only a small number furnish nu- 

 merical expressions sufficiently approximative of the law in ques- 

 tion to be admitted. These expressions vary from 104 to 24 feet 

 for 1° Fahr. of increase ; their mean announces in general a 

 more rapid increase than that hitherto admitted. Their testi- 

 mony has so much the more weight, that they comprise the pro- 

 ducts of several series of sedentary observations. 



4^/j, Lastly, in grouping by countries all the results admissi- 

 ble in whatever degree, I am led to present 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 na- 

 ture of the experiments, but also upon a certain irregularity in 

 the distribution of the subterranean heat in different countries. 



Thus the observations that have hitherto been published pos- 

 sess a real merit, an effective and incontcstible value ; but it is 

 also evident that they leave much to be desired in certain re- 

 spects. In this state of things, as the number is of less import- 

 ance than the choice and accuracy of the experiments, I trust 

 that those in which I have engaged, and of which I shall give 

 an account, will be useful, were it only as first steps in this im- 

 portant investigation *. 



• We hope to find room for Cordier's own experiments in our next Num- 

 ber.— Edit. 



