OF VOLCANOS. 231 



by the height of the mountain, the dimensions of that part 

 of it which is always covered with snow, and the extent and 

 degree to which the sides of the cone of cinders become 

 heated ; but they are not to be regarded as volcanic pheno- 

 mena properly so called. Yast cavities also often exist on 

 the slope or at the foot of volcanos which, communicating 

 through many channels with the mountain torrents, form 

 large subterranean lakes or reservoirs of water. When 

 earthquake shocks, which, in the Andes, usually precede all 

 igneous eruptions, convulse the entire mass of the volcano, 

 these subterranean reservoirs are opened, and there issue 

 from them water, fishes, and tufaceous mud. This is the 

 singular phenomenon which brings to light an otherwise 

 unknown fish, the Pimelodes Cyclopum, called by the inha- 

 bitants of the highlands of Quito " Prenadilla," and which 

 I described soon after my return. When, on the night of 

 the 19th of June, 1698, the summit of a mountain situated 

 to the north of Chimborazo, the Carguairazo, above 19000 

 English feet high, fell in, the country for nearly thirty 

 English geographical square miles round was covered with 

 mud and fishes ; and seven years earlier a putrid fever, in 

 the town of Ibarra, was ascribed to a similar eruption of 

 fish from the volcano of Imbaburu. 



I recall these facts, because they throw some light on the 

 difference between the eruption of dry ashes and miry inun* 

 dations of tufa and trass, carrying with them wood, charcoal, 

 and shells. The quantity of ashes emitted by Vesuvius in 

 the recent eruption, like every thing connected with volcanos 

 and other great natural phenomena of a character to excite 



