358 VIEWS OF NATT7EE. 



natural forces which have their seat deep in the interior of 

 our planet. In Central America (Guatimala) and in the 

 Philippine Islands, the natives even formally distinguish 

 between Volcanes de agua y de fuego, volcanos emitting 

 water, and those emitting fire; designating by the former 

 appellation, mountains from which subterranean waters burst 

 forth from time to time, accompanied by a dull hollow sound 

 and violent earthquakes. 



Without denying the connection, which undoubtedly exists 

 among the phenomena just referred to, it would seem ad- 

 visable to apply more definite terms to the physical as well 

 as to the mineralogical portion of the science of geology, and 

 not at one time to designate by the word volcano a mountain 

 terminating in a permanent fire-emitting mouth, and at 

 another to apply it to any subterranean cause, be it what it 

 may, of volcanic action. In the present condition of our 

 earth, the form of isolated conical mountains (as those of 

 Vesuvius, Etna, the Peak of Tenerifie, Tunguragua and 

 Cotopaxi) is certainly the shape most commonly observed 

 in volcanos. I have myself seen such volcanos varying in 

 height from the most inconsiderable hill to an elevation of 

 more than 19,000 feet above the level of the sea. Besides 

 such conical forms, however, we continually meet with per- 

 manent fire-emitting mouths, in which the communication 

 with the interior of the earth is maintained on far-extended 

 jagged ridges, and not even always from the centre of their 

 mural summits, but at their extremity towards their slope. 

 Such, for instance, is Pichincha, situated between the 

 Pacific and the city of Quito, which has acquired celebrity 

 from Bouguer's earliest barometric formula?, and such are 

 the volcanos on the Steppe de los Pastos, situate at 

 more than 10,000 feet above the level of the sea. All these 

 variously shaped summits consist of trachyte, formerly known 

 as trap-porphyry ; a granular stone full of narrow fissures, 

 composed of different kinds of feldspar (labradorite, o^goklase, 



