226 COSMOS. 



nomena is most strikingly manifested in volcanoes. When 

 the mariner, amid the islands of some distant archipelago, is 

 no longer guided by the light of the same stars with which 

 he had been familiar in his native latitude, and sees himself 

 surrounded by palms and other forms of an exotic vegetation, 

 he still can trace reflected in the individual characteristics of 

 the landscape, the forms of Vesuvius, of the dome-shaped 

 summits of Auvergne, the craters of elevation in the Canaries 

 and Azores, or the fissures of eruption in Iceland. A glance 

 at the satellite of our planet will impart a wider generaliz- 

 ation to this analogy of configuration. By means of the 

 charts that have been drawn in accordance with the observ- 

 ations made with large telescopes, we may recognise in the 

 Moon, where water and air are both absent, vast craters of 

 elevation surrounding or supporting conical mountains, thus 

 affording incontrovertible evidence of the effects produced by 

 the reaction of the interior on the surface, favoured by the 

 influence of a feebler force of gravitation. 



Although volcanoes are justly termed in many languages 

 " fire -emitting mountains," mountains of this kind are not 

 formed by the gradual accumulation of ejected currents of 

 lava ; but their origin seems rather to be a general conse- 

 quence of the sudden elevation of soft masses of trachyte or 

 labradoritic augite. The amount of the elevating force is 

 manifested by the elevation of the volcano, which varies from 

 the inconsiderable height of a hill (as the volcano of Cosirna, one 

 of the Japanese Kurile islands) to that of a cone above 19,000 

 feet in height. It has appeared to me that relations of height 

 have a great influence on the occurrence of eruptions, which 

 are more frequent in low than in elevated volcanoes. I might 

 instance the series presented by the following mountains : 

 Stromboli, 2318 feet; Guacamayo, in the province of Quixos, 

 from which detonations are heard almost daily, (I have myself 

 often heard them at Chillo, near Quito, a distance of eighty- 

 eight miles;) Vesuvius, 3876 feet; Etna, 10871 feet; the 

 Peak of Teneriffe, 12,175 feet; and Cotopaxi, 19,069 feet. 

 If the focus of these volcanoes be at an equal depth below the 

 siu-face, a greater force must be required where the fused 

 masses have to be raised to an elevation six or eight times 

 greater than that of the lower eminences. Whilst the volcano 

 Stromboli (Strongyle) has been incessantly active since the 



