190 COSMOS. 



exactly 147° -2 F. ; and in the Trincheras de Porto Cabello, 

 at a small elevation above the Caribbean Sea, in one basin 

 198^ F., in the other 206O-6 F. The temperature of these 

 hot springs had, therefore, risen unequally in the short inter- 

 val between these two periods — in Mariara about 8°'5 F., 

 and in the Trincheras about 12°*1 F. Boussingault has 

 justly called attention to the 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 surfiice was, indeed, 

 not so strong in the vicinity of the Lake of Tacarigua (Nu- 

 eva Valencia) ; but in the interior of the earth, where elas- 

 tic vapors 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 ? Thb 

 hot waters of the Trincheras, rising from a granite formation, 

 are nearly pure, as they only contain traces of silicic acid, a 

 little sulphureted hydrogen and nitrogen ; after forming nu- 

 merous very picturesque cascades, surrounded by a luxuri- 

 ant vegetation, they constitute a river, the Rio de Aguas 

 calientes; and this, toward the coast, is full of large croco- 

 diles, to which the warmth, already considerably 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 elevation of 10,850 

 feet, almost reaches the boiling point proper to this atmos- 

 pheric pressure.* 



Among the intermittent hot springs, the Icelandic boiling 

 fountains, and of these especially the Great Geyser and 

 Strokkr, have justly attained the greatest celebrity. Ac- 

 cording to the admirable recent investigations of Bunsen, 

 Sartorius von Waltershausen, and Descloiseaux, the tem- 

 perature of the streams of water in both diminishes in a re- 

 markable manner from below upward. The Geyser possess- 

 es a truncated cone of 25 to 30 feet in height, formed by 

 horizontal layers of silicious sinter. ,In this cone there lies 

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

 the funnel of the boiling spring, one third of its diameter, 

 and surrounded by perpendicular walls, goes down to a 



dill^res, in the Annaks de Chimie et de Physique, t. iii., 1833, p. 188- 

 190. 



* Captain Newbold, " On the Temperature of the Wells and Riverff 

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



