VOLCANOES 231 



which approach more nearly to that of Vesuvius. Among all 

 the volcanoes that I have seen in the two hemispheres, the 

 conical form of Cotopaxi is the most beautifully regular. A 

 Eudden fusion of the snow at its cone of cinders announces the 

 proximity of the eruption. Before the smoke is visible in the 

 rarefied strata of air surrounding the summit and the opening 

 of the crater, the walls of the cone of cinders are sometimes 

 in a state of glowing heat, when the whole mountain presents 

 an appearance of the most fearful arid portentous blackness. 

 The crater, which, with very few exceptions, occupies the 

 summit of the volcano, forms a deep, caldron-like valley, which 

 is often accessible, and whose bottom is subject to constant al- 

 terations. The great or lesser depth of the. crater is in many 

 volcanoes likewise a sign of the near or distant occurrence of 

 an eruption. Long, narrow fissures, from which vapors issue 

 ibrth, or small rounding hollows filled with molten masses, al- 

 ternately open and close in the caldron-like valley ; the bottom 

 rises and sinks, eminences of scoriae and cones of eruption are 

 formed, rising sometimes far over the walls of the crater, and 

 continuing for years together to impart to the volcano a pecul- 

 iar character, and then suddenly fall together and disappear 

 during a new eruption. The openings of these cones of erup- 

 tion, which rise from the bottom of the crater, must not, as is 

 too often done, be confounded with the crater which incloses 

 them. If this be inaccessible from extreme depth and from 

 the perpendicular descent, as in the case of the volcano of 

 llucu Pichincha, which is 15,920 feet in height, the traveler 

 may look from the edge on the summit of the mountains which 

 rise in the sulphurous atmosphere of the valley at his feet ; 

 and I have never beheld a grander or more remarkable picture 

 than that presented by this volcano. In the interval between 

 two eruptions, a crater may either present no luminous ap- 

 pearance, showing merely open fissures and ascending vapors, 

 or the scarcely heated soil may be covered by eminences of 

 scoria;, that admit of being approached without danger, and 

 thus present to the geologist the spectacle of the eruption of 

 burning and fused masses, which fall back on the ledge of the 

 cone of scoriae, and whose appearance is regularly announced 

 by small wholly local earthquakes. Lava sometimes streams 

 ibrth from the open fissures and small hollows, without break- 

 ing through or escaping beyond the sides of the cxater. If, 

 however, it does break through, the newly-opened terrestrial 

 itream generally flows in such a quiet and well-defined course, 

 that the deep valley, which we term the crater, remains acees 



