VOLCANOES. 229 



blackness. The crater, which, with very few exceptions, occu- 

 pies the summit of the volcano, forms a deep cauldron-like 

 valley, which is often accessible, and whose bottom is subject 

 to constant alterations. 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 

 vapours issue forth, or small roundish hollows filled with 

 molten masses, alternately open and close in the cauldron-like 

 valley ; the bottom rises and sinks, eminences of scoria? and 

 cones of eruption are formed, rising sometimes far over the 

 walls of the crater, and continuing for years together to im- 

 part to the volcano a peculiar character, and then suddenly 

 fall together and disappear during a new eruption. The 

 openings of these cones of eruption, which rise from the 

 bottom of the crater, must not, as is too often done, be con- 

 founded with the crater which encloses them. If this be in- 

 accessible from extreme depth and from the perpendicular 

 descent, as in the case of the volcano of Rucu-Pichineha, 

 which is 15,920 feet in height, the traveller 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 erup- 

 tions, a crater may either present no luminous appearance, 

 showing merely open fissures and ascending vapours, or the 

 scarcely heated soil may be covered by eminences of scoriae, 

 that admit of being approached without danger, and thus pre- 

 sent 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 forth from 

 the open fissures and small hollows, without breaking through 

 or escaping beyond the sides of the crater. If, however, it does 

 break through, the newly-opened terrestrial stream generally 

 flows in such a quiet and well-defined course, that the deep 

 valley, which we term the crater, remains accessible even 

 during periods of eruption. It is impossible, without, an ex- 

 act representation of the configuration the normal type, as 

 it were, of fire-emitting mountains, to form a just idea of those 

 phenomena, which, owing to fantastic descriptions and an 

 undefined phraseology, have long been comprised under the 



