TRUE VOLCANOES. 303 



or the temporary opening of new ones, in the course of 

 ages, render simultaneous eruption at very distant points 

 quite conceivable. I may again advert to the sudden dis- 

 appearance of the column of smoke which ascended from 

 the volcano of Pasto, when, on the morning of the 4th of 

 February, 1797, the fearful earthquake of Riobamba con- 

 vulsed the plateau of Quito between Tunguragua and Coto- 

 paxi.* 8 



To the volcanoes of the island of Java generally, a cha- 

 racter of ribbed formation is ascribed, to which I have seen 

 nothing similar in the Canary Islands, in Mexico, or in the 

 Cordilleras of Quito. The most recent traveller, to whom 

 we are indebted for such admirable observations upon the 

 structure of the volcanoes, the geography of plants, and the 

 psychrometric conditions of moisture, has described the 

 phenomenon to which I here allude with such decided clear- 

 ness that I must not omit to call attention to this regularity 

 of- form, in order to furnish an inducement to new investi- 

 gations. " Although," says Junghuhii, " the surface of a vol- 

 cano 10,974 feet in height, the Gunung Sumbing, when seen 

 from some distance, appears as an uninterruptedly smooth and 

 sloping fkce of the conical mountain, still, on a closer examina- 

 tion, we find that it consists entirely of separate longitudinal 

 ridges or ribs, which gradually subdivide and become broader 

 as they advance downwards They run from the summit of 

 the volcano, or more frequently from an elevation several 

 hundred feet below the summit, down to the foot of the 

 mountain, diverging like the ribs of an umbrella." These 

 rib-like longitudinal ridges have sometimes a tortuous course 

 for a short distance, but are all formed by approximated 

 clefts of three or four hundred feet in depth, all directed in 

 the same way, and becoming broader as they descend. They 

 are furrows of the surface " which occur on the lateral slopes 

 of all the volcanoes of the island of Java, but differ consi- 

 derably from each other upon the various conical mountains, 

 in their average depth and the distance of their upper 

 origin from the margin of the crater or from an unopened 

 summit. The Gummg Sumbing (11,029 feet) is one of those 

 volcanoes which exhibit the finest and most regularly formed 



92 Cosmos, vol. v, p. 183, and Voyage aux Regions Equinox, t. ii, 

 p. 16. 



