OF VOLCANOS. 379 



Teneriffe, and the Aleutian Islands near the polar circle. The ob- 

 jects to be observed were assembled within a moderate distance; yet 

 distant voyages, and the comparison of extensive regions in and out 

 of Europe, have been required for the clear perception and recog- 

 nition -of the resemblance between volcanic phenomena and their 

 dependence on each other. 



Our ordinary language, which often gives permanency and apparent 

 authority to the first-formed erroneous views of natural phenomena, 

 but which also often points instinctively to the truth. our ordinary lan- 

 guage, I repeat, applies the term " volcanic" to all eruptions of sub- 

 terranean fires or molten substances; to columns of smoke and vapor 

 rising from rocks, as at Colares, after the great earthquake of Lisbon; 

 to " Salses" or mud volcanos, argillaceous cones emitting mud, as- 

 phalte, and hydrogen, as at Girgenti in Sicily, and at Turbaco in 

 South America ; to the Geysers, hot springs in which, as in those of 

 Iceland, the waters, pressed by elastic vapors, rise in jets to a con- 

 siderable altitude; and, in general, to all operations of natural forces 

 having their seat in the interior of our planet. In Central America 

 (Guatimala), and in the Philippine Islands, the natives even dis- 

 tinguish formally between water and fire-volcanos, Volcanes de agua 

 y de fuego, giving the former name to those mountains from which 

 subterranean waters issue from time to time with violent earthquake 

 shocks and a hollow noise. 



Not denying the connection of the different phenomena which 

 have been referred to, it yet appears desirable to give greater pre- 

 cision to the terms employed in the physical as well as in the 

 mineralogical part of geology, and not to apply the word "volcano" 

 at one moment to a mountain terminating in a permanent igneous 

 opening or fiery crater, and at another to every subterranean cause 

 of volcanic phenomena. In the present state of our planet, the 

 most ordinary form of volcanos is indeed in all parts of the globe 

 that of an isolated conical mountain, such as Vesuvius, Etna, the 

 Peak of Teneriffe, Tunguragua, and Cotopaxi. I have myself seen 

 such volcanos varying in size from the smallest hill to an elevation 

 of 18,000 (19,184 English) feet above the sea. But, besides these 

 isolated cones, there are also permanent openings or craters, having 

 established channels of communication with the interior of the 



