Hot and Thermal Springs. 289 



rality of this assertion, since local circumstances may some- 

 times, as, for instance, in the Sauberg at EhrerifriedersdorJ 

 (see Chap. VI.), cause a decrease of temperature to a certain 

 depth. This may, perhaps, also be the case in the Swedish 

 mines.* 



Even the most strenuous opponent must be convinced when 

 he considers the high temperature possessed by considerable 

 bodies of water collected in deserted mines. It is impossible to 

 conceive any other cause for this than the innate heat of the 

 walls of the cavities in which the water accumulates. But the 

 temperature of these walls cannot be ascribed to any other 

 cause than the natural high temperature of the earth at a cer- 

 tain depth. Thus, Fox relates that in 3820 the water in the 

 copper and tin mine of Poldice, at a depth of 144 fathoms, had 

 a temperature of 79°.92 F., whilst in 1830, when the workings 

 had been carried to a depth of 176 feet, il rose to 99°.95 F.-f- 



A I'are opportunity of observing the temperature of an insu- 

 lated body of water presented itself to Reich. | In a mine near 

 Freyherg, a supply of water of several cubic feet per minute 

 was cut ofi, for the sake of prosecuting the works, at a depth 

 of 916 — 6.7 feet, by means of a KeUverspundens. This was 

 composed of wedge-shaped pieces of wood of 6 — 4.7 feet long, 

 which fitted so exactly together, and against the smooth-hewn 

 walls of the gallery, that, notwithstanding a pressure of 18 at- 

 mospheres, a very small quantity of water could escape ; on the 

 20th of March 1833, the escape was only 0.326 cubic feet in 

 an hour. In this manner a space of 62 feet long, 6 feet high, 

 and 3 feet wide, was shut off and filled with water, which had 

 hardly any communication with the gallery. Reich carefully 

 examined the temperature of this body of water on the 30th 

 September 1832, and on the 20th March 1833. These seasons 

 were chosen, because, if the influence of the seasons should 

 be perceptible, it would on these days be the most striking. 

 On the 30th September, he found the temperature of the wa- 

 ter, from five perfectly accordant observations, to be 61°.65, 



• Bergman, Pbysikal-Erdbeschreibunfr, 1780-4, vol. ii. p. 118; and Wald 

 mann in Berzelius' Jahresbericht, vol. i. p. 141). 

 + Pogpjend. Annal. vol. xxi. p. 171. 

 X Loco citato, p. 134. 



