Hot and Thermal Springs. 287 



The following is borrowed from Cordier's comparative re- 

 sults of these observations. 



The mean depth in which the temperature rises, 2°.25 F. or 

 1° R. is, 1st, From the observations of the temperature of the 

 springs ; in Saxony, 188 feet 7-7 inches (English feet) ; in 

 Poullaouen, 450 — 10 ; in Huetgoet, 122 — 6 ; in Cornwall, 102 

 — 4 ; in Mexico, 102 — 4. 2d, From the observations on the 

 temperature of the workings of the mines : in Cornzcall, 69 — 

 3 ; in Devonshire, 110 — 10 ; in Bex, 106 — 6.9 ; in Poullaouen, 

 262 — 2. 3d, From the observations on the temperature of 

 considerable bodies of water in the mines : in Cornwall, 118 — 

 4; in Saxony, 139 — 7; in Hvetgoet, 175 — 10. 4th, From 

 observations on the temperature of the rock in mines ; in Saxony 

 198—3 ; in Cornwall, 69—3 to 122-,6. 



Cordier's own observations give a mean of 147 — 10.2 and 

 61 — 9.7 feet. As a general result, he asserts that the increase 

 in the internal heat of the earth does not every where follow the 

 same law; that it may be twice or even three times as rapid in 

 one country as in another ; that these differences are totally in- 

 dependent of latitude and longitude, and that the increase is 

 certainly greater than has been generally supposed. According 

 to him, an increase of (1° 11.) 2°.25 may take place in 61 — 9-7, 

 or even 53 — 3.4 feet ; but for the present he takes it at 102 — 

 3.7. Kupff'er * attempts, but with little success, to reconcile 

 the irregulai'ities in these results. Still less can we agree with 

 him, in wishing to determine the mean temperature of the soil 

 from the increase of temperature observed at any particular 

 place. 



According to the above-mentioned observations in the mines, 

 of Prussia, the calculated depth in which the temperature in- 

 creases 2\25 F. (1°R.), varies from 63—11.3, 473—5.4 feet.f 

 The latest observations in the Erzgcbirge also yield very vari- 

 ous results ; indeed, in the Neue Hoffnung Gottes at Brduns- 

 dorf, and in the Stockwerk at Altenherg, the temperature is 

 ob.served in some cases to decrease. Reich, therefore, calcula- 

 ted the most probable mean from all the results, by taking into 

 consideration, as far as he was able, all the causes which might 



* Toggend. Annul, vol. xv. 171. See also lleich, 1. c. p. 149. 

 t Loco citato, p. 028. 



u2 



