490 



Trincheras (90*4°) on its southern slope, and 

 those of Onoto and Mariara on its southern 

 slope. The former issue from a granite with 

 large grains, very regularly stratified ; the latter 

 from a rock of gneiss. What especially cha- 

 racterizes the northern chain, is a summit which 

 is not only the loftiest of the system of the 

 mountains of Venezuela, but of all South Ame- 

 rica, on the east of the Andes. The eastern 

 summit of the Silla of Caraccas, according to 

 my barometric measurement, made in 1800, is 

 1350 toises high*. MM. Boussingault and 

 Rivero carried an excellent barometer of For- 

 tin, in 1822, on this very summit, which they 

 found to be from 1351 1 toises ; this proves that 

 notwithstanding the commotion which took 

 place on the Silla during the great earthquake 



Mexico,) still hotter than the thermal waters of las Trinche- 

 ras, situated on the south of Porto Cabello. The waters of 

 Comangillas flow at 1040 toises high, and are alike remark- 

 able for their purity, and their temperature of 96* 3° cent. 



* Vol. Hi, p. 505 ; Vol. iv, p. 21. The Silla of Caraccas 

 is only 80 4 toises lower than the Canigou in the Pyrenees. 

 As Caraccas, Santa Fe de Bogota, and Quito, may be consi- 

 dered as the three capitals of Columbia, I shall here repeat, 

 in order to establish a precise comparison of the height of 

 those three towns, that the inhabitants of Caraccas recog- 

 nize at once in the summit of the Silla which commands 

 their town, the level of the plains of Bogota, and a point of 

 150 toises, which is less elevated than the great square of 

 Quito. 



