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-* 
fleeting on this fact, and comparing it with our 
observations on the bochenuewe 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, tom. 1, p, 47. 
