AND ITS DISTRIBUTION. 37 



less rapid at Paris, or at the rate of about 7*1 French 

 feet more for each centesimal degree. I have already 

 noticed ( 35 ) that a very similar result was obtained by 

 Auguste de la Eive and Marcet in a boring examined by 

 them at Bregny, near Geneva, having a depth of only 680 

 French, or 724*7 English feet, although situated at more 

 than 1600 English feet above the Mediterranean. 



If to the three wells which have been mentioned, which 

 attain depths of from 680 to 2144 Paris, or 725 to 2285 

 English, feet, we add that of Wearmouth, near Newcastle 

 (being the pit waters of the coal-mine in which, according to 

 Phillips, men work at a depth of 1404 French, or 1496 

 English, feet below the level of the sea), we find the remark- 

 able result, that at four places so distant from each other, 

 the increase of temperature only varies between 91 and 99 

 Paris feet for 1 Centigrade. ( 36 ) Such an accordance 

 cannot, however, from the nature of the means employed, 

 be everywhere looked for in inquiries into the internal heat 

 of the earth at given depths. Admitting that the meteoric 

 water falling on heights, and penetrating by infiltration, 

 produces by hydrostatic pressure, as in connected tubes, the 

 ascent of springs at lower points ; and that the subterranean 

 waters assume the temperature of the strata with which they 

 come into contact ; they may nevertheless, in certain cases, 

 have channels of communication with still deeper clefts, 

 from whence they may receive accessions of still warmer 

 water from unknown depths. Such an influence, which is 

 to be altogether distinguished from different degrees of con- 

 ducting power in the surrounding rocks, may take place at 

 points very distant from the shaft or boring of the well. It 

 is probable that the subterranean waters exist sometimes in 



