103 



ferences in the level of the ground more easy to 

 be understood. 



The cones are so many funnels, which exhale 

 a thick vapour, and communicate an insupport- 

 able heat to the surrounding air. They are call- 

 ed in this country, which is excessively unhealthy, 

 by the name of the little ovens, hornitas. They 

 contain nodules of basalt embedded in a mass of 

 indurated clay. The slope of the great volcano, 

 which is constantly burning, is covered with 

 ashes. We reached the inside of the crater by 

 climbing the hill of scorified and branching 

 lavas, represented in the engraving toward the 

 left, and which rises to a considerable height. 

 We shall here observe as a remarkable fact*, 

 that all the volcanoes of Mexico are ranged in a 

 line from east to west ; and which forms at the 

 same time a parallel of great elevations. In re- 

 flecting on this fact, and comparing it with our 

 observations on the bochenuove of Vesuvius, we 

 are tempted to suppose, that the subterraneous 

 fire has pierced through an enormous crevice, 

 which exists in the bowels of the Earth between 

 the latitudes of 18° 59' and 19° 12', and stretches 

 from the Pacific to the Atlantic Ocean. 



* Political Essay, torn. 1, p. 47. 



