§ 16. VOLCANO OF KIRAUEA. 833 



end of the ridge, where, the sides being less steep, a descent to the 

 plain below seemed practicable ; but it required the greatest caution, 

 as the stones and fragments of rock frequently gave way under our 

 feet, and rolled down from above. The steep which we had descended 

 was formed of volcanic matter, apparently of light red and grey vesi- 

 cular lava, lying in horizontal beds, varying in thickness from one to 

 forty feet. In a few places the different masses were rent in perpen- 

 dicular and oblique directions, from top to bottom, either by earth- 

 quakes, or bv other violent convulsions of the ground. After walking 

 some distance over the plain, which in several places sounded hollow 

 beneath our feet, we came to the edge of the great crater. Before us 

 yawned an immense gulf in the form of a crescent, about two miles in 

 length from north-east to south-west, one mile in width, and 800 feet 

 deep. The bottom was covered with lava, and the south-west and 

 northern parts were one vast flood of burning matter. Fifty-one 

 conical islands of varied form and size, containing as many craters, 

 rose either round the edge or from the surface of the burning lake. 

 Twenty-two constantly emitted either columns of grey smoke, or 

 pyramids of brilliant flame : and at the same time vomited from their 

 ignited mouths streams of lava, which rolled in blazing torrents down 

 their black indented sides into the boiling mass below {see Lign. 186). 

 The existence of these conical craters led us to conclude, that the 

 boiling cauldron of lava did not form the focus of the volcano, but 

 that this liquid mass was comparatively shallow, and the basin 

 which contained it separated by a stratum of solid matter from 

 the great volcanic abyss, which constantly poured out its melted 

 contents through these numerous craters into this upper reservoir. 

 We were further inclined to this opinion from the vast columns of 

 vapour continually ascending from the chasms in the vicinity of the 

 sulphur banks and pools of water, for they must have been produced 

 by other fire than that which caused the ebullition in the lava at the 

 bottom of the great crater ; and also by noticing a number of small 

 vents in vigorous action high up the sides of the great gulf, and 

 apparently quite detached from it. The streams of lava which they 

 emitted rolled down into the lake, and mingled with the melted mass, 

 which, though thrown up by different apertures, had perhaps been 

 originally fused in one vast furnace. The sides of the gulf before us, 

 although composed of different beds of ancient lava, were perpendicu- 

 lar for about 400 feet, and rose from a wide horizontal ledge of solid 

 black lava, of irregular width, but extending completely round. 

 Beneath this ledge the sides sloped gradually towards the burning 

 lake, which was, as nearly as we could judge, three or four hundred 



