and Spouting Foimtahis. 23S 



producing heat. It was also argued, that the presence of the 

 workmen, and the hghted flambeaux, the explosions of gun- 

 powder, &c. &c. produced the eflPect ; and although minute cal- 

 culations had demonstrated how entirely all these causes, when 

 united, were insufficient for the explanation of the phenomenon, 

 still many obstinately remained in a state of doubt. An obser- 

 vation which 1 made in October 1821, whilst, in concert with 

 Messrs Colby, Kater, and Mathieu, I was connecting, by geo- 

 desic operations, the opposite coasts of France and England, 

 opened to my view a mode in which the problem might be 

 solved in a manner which would be wholly unobjectionable. I 

 then found that the temperature of the springs which rose at the 

 foot of the cliff of Cape Blanc-Nez was notably higher than the 

 mean temperature of the water of the neighbouring wells of 

 Montlambert. 



From that moment the determination of die temperatures of 

 the projecting fountains presented itself to my mind as a sub- 

 ject of research full of interest ; it appeared to me that the wa- 

 ter of these fountains could not fail, especially if they were at 

 all abundant, to reach the surface with the same degree of heat 

 which the interior beds, usually horizontal, and between which 

 the waters were confined, possessed. At all events, it was not 

 to be doubted that, in the same country, if the earth really had 

 a peculiar proper heat, and this was precisely the subject under 

 discussion, the maximum of temperature ought to be found in 

 those waters which came from the deepest springs. According- 

 ly, for nearly fourteen years I have lost no opportunity of col- 

 lecting, by myself, or with the help of friends, thermometrical 

 documents which ally themselves in the closest way with the 

 history of the globe. I hope soon to be able to present these to 

 the public, and I shall not fail to combine with them the results 

 to which they lead. On the present occasion, however, I must 

 limit myself, with the help of a inw selected results, to demon- 

 strata the problem, that everywhere the temperature of artesian 

 wells is higher than that of the surface, in the ratio of 9° for 

 every sixty or eighty feet of depth (1° Cent, for every twenty to 

 thirty metres of depth.) 



