198 COSMOS. 



and in the Trinoheras de Portocabello, at a small eleva- 

 tion above the Caribbean Sea, in one basin 198 F., in the 

 other 206. 6 F. The temperature of these hot springs had 

 therefore risen unequally in the short interval between these 

 two periods : in Mariara about 8. 5 F., and in the Trincheras 

 about 12 1 F. Boussingault has justly called attention to 

 ti e fact, that it was in the above mentioned interval that the 

 fearful earthquake took place, which overwhelmed the city 

 of Caraccas on the 26th of March, 1812. The commotion at 

 the surface was indeed not so strong in the vicinity of the 

 lake of Tacarigua (Nueva Valencia) ; but in the interior of 

 the earth, where elastic vapours act upon fissures, may not a 

 movement which propagated itself so far and so powerfully, 

 readily alter the net-work of fissures and open deeper canals 

 of supply ? The hot waters of the Trincheras, rising from a 

 granite formation, are nearly pure, as they only contain traces 

 of silicic acid, a little sulphuretted hydrogen and nitrogen ; 

 after forming numerous, very picturesque cascades, sur- 

 rounded by a luxuriant vegetation, they constitute a river, 

 the Rio de Aguas calientes ; and this, towards the coast, is 

 full of large crocodiles, to which the warmth, already con- 

 siderably diminished, is very suitable. In the most northern 

 parts of India (30 52' N. lat.), and also from granite, issues 

 the very hot well of Jumnotri which attains a temperature 

 of 194 F., and as it presents this high temperature at an ele- 

 vation of 10,850 feet almost reaches the boiling point pro- 

 per to this atmospheric pressure. 49 



Amongst the intermittent hot springs, the Icelandic boil- 

 ing fountains, and of these especially the Great Geysir and 

 Strokkr, have justly attained the greatest celebrity. Ac- 

 cording to the admirable recent investigations of Bunsen. 

 Sartorius von Waltershausen and Descloiseaux the tempe- 

 rature of the streams of water in both diminishes in a remark- 

 able manner from below upwards. The Geysir possesses a 

 truncated cone of 25 to 30 feet in height formed by hori- 

 zontal layers of silicious sinter. In this cone there lies a 

 shallow basin of 52 feet in diameter, in the centre of which 



leres," in the Annales de Chimie et de Physique, t. Hi, 1833, pp. 188 

 190. 



49 Captain Newbold, " On the Temperature of the Wells and Pavers 

 in India and Egypt" (Phil. Transact, for 1845, pt. i, p. 127). 



