Hot and Thermal Springs. 385 



perature of the place by about S^.^S. Some springs bored for 

 in the East Pyrenees also exceed the mean temperature of that 

 country by several degrees ; thus one at a depth of 80 feet had 

 60''.35, exactly the same as the running springs in the neigh- 

 bourhood ; a second, at a greater depth, shewed 62°.825.* Last- 

 ly, at Rudersdorf, near Berlin, in the chalk formation, water of 

 74°.3 was obtained at a depth of 880 feet, 770 feet below the 

 surface of the sea.-f* 



This comparison of the temj)eratures of springs shews that 

 thermal waters are to be found in all formations very abundant- 

 ly. They are found in the youngest members of the second- 

 ary series, as well as in the oldest neptunian and in volcanic 

 rocks. We find them below the level of the sea, a few hundred 

 feet above it, and at heights of 2000 to 12,000 feet. J Warm 



• Bulletin de la Societe Geolog. de France, vol. iv. p. 214. 



f Poggendorfi's Annalen, vol. xxviii. p. 233. 



X I only mention a few warm springs as examples : Ems lies 291 feet 

 above the level of the sea, Wiesbaden 323 feet, Aix-la-Chapelle 400 to 500 

 feet, Pfaeffers 2128 feet, Gastein 3100 feet, Leuk 4400 feet, Brennersbad hi 

 Tyrol (72°. 5), 4500 feet ; the warm springs of Dux (56°.75 to 72°. 5, disco- 

 vered by Ennemoser), 5600 feet. In the Cordilleras rise the sulphurous 

 springs of Juan {Q{i°.G) and Aqua Tibia (96°.8), at a height of 12313 feet above 

 the sea. Boussingault remarks (Annales de Chimie et de Physique, vol. 111. 

 p. 181), that at different points in the Cordilleras, there are appearances which 

 speak in favour of the opinion that the heat of warm springs is caused by the 

 superior temperature of the interior of the earth. Thus, it seems that the 

 hot springs in the chain of Venezuela have a less elevated temperature the 

 higher they are situated ; for example, the hot spring at Las Trincheras, near 

 Puerto Cabello, ahnost on the level of the sea, has 206°.6 ; the spring of Ma- 

 riana, 1465 feet above the sea, only 147°.2; and the waters of Onoto, at a 

 height of 2161 feet, only 112°.l. In the trachytic districts, particularly in 

 the vicinity of volcanos, this regularity in the decrease of the temperature of 

 the springs is no longer observable ; and it seems that in this case the local 

 cause, which occasions the volcanic phenomena, has an extraordinary influence 

 upon the temperature of these waters. Anglada (p. 54) shews, on the other 

 hand, that the temperature of thermal springs does not always decrease with 

 the increase of elevation at which they rise. But how could such be always 

 expected, even if they were only indebted to the heat of the interior of the 

 earth for their superior temperature ? For, since their temperature depends 

 upon the depth to which the meteoric waters sink through the clefts, it may 

 easily happen that a spring rising at a greater elevation, but coming from a 

 greater depth, should have a higher temperature than another rising at a 

 lower level, but from a lesser depth. 



