THERMAL SPRINGS. 197 



same time to remind one of the cold hells of the Buddhists, 

 an aqua gelidissima concrescens in glaciem is admitted, 

 somewhat unphysically and notwithstanding the depth, for 

 the nunquam jhiiendum siipplicium impiorum. 



Amongst hot springs, those which, approaching the boil- 

 ing heat of water, attain a temperature of 194F., are far more 

 rare than is usually supposed in consequence of inexact ob- 

 servations ; least of all do they occur in the vicinity of still 

 active volcanoes. I was so fortunate, during my American 

 travels, as to investigate two of the most important of these 

 springs, both between the tropics. In Mexico, not far from 

 the rich silver mines of Guanaxuato, in 21 N. lat., and at an 

 elevation of about 6500 feet above the surface of the sea; 

 near Chichermquillo. 46 the Aquas de Comangillas burst forth 

 from a mountain of basalt and basaltic breccia. In Septem- 

 ber, 1803, 1 found their temperature to be 205.5 F. This mass 

 of basalt has broken in the form of veins through a columnar 

 porphyry, which again rests upon a white syenite rich in 

 quartz. At a greater elevation, but not far from this nearly 

 boiling spring, near los Jbares, to the north of Santa Rosa 

 de la Sierra, snow falls from December to April even at an 

 elevation of 8,700 feet, and the inhabitants prepare ice the 

 whole year round, by radiation in artificial basins. On the 

 road from Nueva Valencia in the Valles de Aragua, towards 

 the harbour of Portocabello (in about 10i of latitude), 

 on the northern slope of the coast chain of Venezuela, I saw 

 the aquas calientes de las Trincheras springing from a strati- 

 fied granite, which does not pass at all into gneiss. I found 47 

 the springs in February, 1800, at 194.5 F., whilst the 

 Banos de Mariara in the Valles de Aragua,, which belong to 

 the gneiss, showed a temperature of 138.7 F. Twenty- 

 three years later, and again in the month of February, Bous- 

 singault and Rivero* 8 found in the Mariara exactly 147.2 F. ; 



46 Humboldt, Essai Politique sur la Nouvelle Espayne, ed. 2, t. iii 

 (1827), p. 190. 



4 ? Relation Historique, t. ii, p. 98; Cosmos, vol. i, p. 219. The hot 

 springs of Carlsbad also originate in the granite (Leop. von Buch, in 

 Poggend. Annalen, Bd. xii, s. 230), just like the hot springs of Momay, 

 in Thibet, visited by Joseph Hooker, which break forth near Chan- 

 grokhang, at an elevation of 16,000 feet above the sea, with a temper- 

 ature of 115 (Himalayan Journal, vol. ii, p. 133). 



4 ' Boussingault, " Considerations sur les ea".x thermales des Cordfi 



