TRUE VOLCANOES. 329 



putati^n of furnishing no lava-streams, but only incoherent, 

 glowing scoriaceous masses, thrown out of the single summital 

 crater, and often rolling down in a linear arrangement. This 

 was even the opinion 22 of La Condamine, when he left the 

 highlands of Quito and Cuen$a in the spring of 1743. Four- 

 teen years afterwards, when he returned from an ascent of 

 Vesuvius (4th June, 1755), in which he accompanied the 

 sister of Frederick the Great, the Margravine of Baireuth, 

 he had the opportunity of expressing himself warmly, in a 

 meeting of the French Academy, upon the want of true 

 lava-streams (laves coulees par torrens de matieres liquefiees) 

 22 " I have never known," says La Condamine, "lava-like matter in 

 America, although M. Bouguer and myself have encamped for whole 

 weeks and months upon the volcanoes, and especially upon those of 

 Pichincha, Cotopaxi, and Chimborazo. Upon these mountains I have 

 only seen traces of calcination, without liquefaction. Nevertheless, the 

 kind of blackish crystal, commonly called Piedra de Gallinafo in Peru 

 (obsidian), of which I have brought home several fragments, and of 

 which a polished lens of seven or eight inches in diameter, may be seen 

 in the cabinet of the Jardin du Roi, is nothing but a glass formed 

 by volcanic action. The materials of the stream of fire which flows 

 continually from that of Sangai, in the province of Macas, to the south- 

 east of Quito, are no doubt lava, but we have only seen this mountain 

 from a distance, and I was no longer at Quito at the time of the last 

 eruptions of the volcano of Cotopaxi, when vents opened upon its 

 flanks, from which ignited and liquid matters were seen to issue in 

 streams, which must have been of a similar nature to the lava of 

 Vesuvius" (La Condamine, Journal de Voyage en Italic, in the 

 Hemoires de VAcad. des Sciences, 1757, p. 357, Historic, p. 12). The 

 two examples, especiallythe first, are not happily chosen. The Sangay 

 was first scientifically examined in December of the year 1849, by 

 Sebastian Wisse ; what La Condamine, at a distance of 108 miles, 

 took for luminous lava flowing down, and "an effusion of burning 

 sulphur and bitumen," consists of red-hot stones and scoriaceous 

 masses, which sometimes, pressed closely together, slip down on the 

 steep declivities of the cone of ashes (Cosmos, see above, p. 264). On 

 Cotopaxi, as on Tungurahua, Chimborazo, and Pichincha, or on 

 Purace, and Sotara near Popayan, I have seen nothing that could be 

 looked upon as narrow lava-streams, which had flowed from these 

 colossal mountains. The incoherent, glowing masses of 5 6 feet in 

 diameter, often containing obsidian, which Cotopaxi has scattered 

 abroad during its eruptions, impelled by floods of melting snow and 

 ice, have reached far into the plain, where they form rows partially 

 diverging in a radiate form. La Condamine also says very truly else- 

 where (Journal du Voyage a T Equateur, p. 160): '''These fragments of 

 rock, as large as the hut of an Indian, form series of rays, which start 

 from the volcano as from a common centre." 



