290 Baron Humboldt on Volcanoes. 



from 9000 to 12,000 feet* high, as in the double chain of the 

 Andes of Quito, this circumstance may very well give rise to 

 the fact, that the most violent eruptions, when red-hot ashes 

 and scoriae are thrown out with detonations that are heard for 

 hundreds of miles around, are never accompanied with streams 

 of lava. This is the case with the volcanoes of Popayan, of 

 the lofty plains of Los Pastos, and of the Andes of Quito ; the 

 single volcano of Antisana, among the latter, perhaps excepted. 



The height of the cone of ashes, and the dimensions and 

 form of the crater, are the elements in the figure of volcanoes 

 which more particularly impress upon each of them an indi- 

 vidual character ; but of these elements, both the cone and the 

 crater are perfectly independent of the magnitude of the whole 

 mountain. Vesuvius is not one-third of the height of the Peak 

 of Teneriffe, yet its cone of ashes forms one-third of the whole 

 height of the mountain, whilst the cone of ashes of the Peak 

 is only one-twenty-second of the entire elevation. In the case 

 of another volcano of much greater height than the Peak, that 

 of Rucu-Pinchincha, namely, the relations come nearer to 

 those of Vesuvius. Of all the volcanoes I have seen in either 

 hemisphere, Cotopaxi is that of which the conical form is the 

 most regular and beavitiful. A sudden meltinsj of the snow of 

 its cone of ashes indicates the proximity of an eruption. Be- 

 fore there is even any smoke visible in the attenuated strata 

 of the atmosphere that surround the summit of the crater's 

 mouth, the walls of the ash-cone are sometimes heated through, 

 when the entire mountain presents the most threatening and 

 ill-omened aspect. 



The crater which, except in very rare cases, occupies the 

 summit of the volcano, forms a deep, and often accessible, 

 basin-shaped valley, whose bottom is subject to incessant 

 changes. The greater or less depth of the crater is, in many 

 volcanoes, an indication of the proximity or remoteness of an 

 eruption. In the basin-shaped crater, extensive fissures open 

 and close again ah ernately, through which, vapours of various 

 kinds find vent, or small, rounded, and fiery openings, filled 

 with molten matters are seen. The floor rises and falls, 

 and in it are formed hillocks of ashes and cones of erup- 



* French feet in this and every other instance in the present paper. 



