How the Lai' a Floivcd. 73 



stalactites, draped with filameiitoas vitrifications, and encrnsted with sulphur, sulphate of lime and 

 other salts. The outside of these cones are inclined planes, on an angle of forty to sixty degrees, 

 and composed of pumice, cinder, volcanic sand, etc. You will not, however, understand that these 

 semi-cones were once entire, and that they have been vent. They are simply masses or ridges of 

 cinder and dross deposited on each side of the fractures where the action is greatest. If is all a 

 ncii' deposit. [See a similar cone painted by D. Howard Hitchcock in the eruption of 1899.] xVfter 

 you leave the region of open fissures, near the summit of the mountain, all below appears to be a flow 

 on the surface. 



I St. We can see no chasms or fractures except those always foinul in the surface flows. 

 There is no visible evidence that the old substrata had been fractured except on the higher regions 

 of the mountain." 



2d. Where there is a throat extending down to the fiery abyss below, there will, we think, 

 always be a column of smoke and gaseous vapor ascending to mark the spot, so long as action con- 

 tinues. This is true of Kilauea, and it is also true of all the eruptions I have noticed. Now if you 

 were at Hilo, you would see a continuous volume of smoke ascending from the terminal point, and 

 another from the terminus of the stream — separated in a direct line forty miles, and by route of the 

 flow seventy miles — while between these extreme points you see no smoke and have no evidence of 

 fire beneath'** except the radiation of heat as you pass up. The smoke at the fountain is mineral, 

 that at the end of the stream is from vegetation, and only here the fusion now makes its appearance, 

 having come, as I believe, all the way from the mountain under cover, without showing itself at a 

 single point. I do not mean that it has tunnelled the mountain, or melted a lateral duct through its 

 mural sides. The process is this: lavas flowing on the surface and exposed to the atmosphere, un- 

 less moving with great velocity, as down steep hills, soon refrigerate on the surface. This hardened 

 surface thickens, until it extends downward from one to two hundred feet, as the case may be. 

 Under this superstratum the lava remains liqviid ; consequently at the termini and sometimes along 

 the margins of the hardened streams you see the fusion gushing out in lines and points, and in irregu- 

 lar masses. When lavas refrigerate through the whole stratum, and thus rest on an ancient or pre- 

 vious formation, they form dams which divert the stream of lava from above, unless this obstruction 

 is broken up, tilted, or overflowed by fresh lava. Down the steep sides of the mountain such ob- 

 structions occur more rarely ; consequently the lava ceases to reach the surface either at the foun- 

 tain or down the sides of the mountain, but is confined to channels, mostly covered with fresh, 

 solidified lavas, where it finds a free and rapid passage to the plains below. Here the movement is 

 slow, the obstructions more numerous, and the force to overcome them less patent. This accounts 

 for the spreading laterally, the upliftings, and the ten thousand irregularities which diversify the 

 ever-changing surface of lava streams. I have seen a dome, some three hundred feet in diameter 

 at base, raised one hundred feet high and split from the summit in numerous radii, through which the 

 red and viscid fusion was seen ; and I have mounted to the top of such a dome in this state, thrust 

 my pole into the liquid fire and measured the thickness of its shell, which was from two to five feet. 

 Wherever vegetable matter is being consumed there is smoke ; when this is exhausted there is none. 

 Consequently I argue that there are no fissures extending to the central fires of the earth, except for 

 a few miles near the summit of the mountain. 



3d. Again, and what is more reliable, I have surveyed the ground upon which lava-streams 

 have been approaching, for distances of five to twenty miles, and have seen the burning flood move 

 on, covering today the ground on which I traveled yesterday, and consuming the hut where I slept; 

 and the process is so familiar that it is difficult to see how I can be mistaken. I think that this stream 



"A careful examination of the line of eruption resulted in the conviction that the fissure was originally very 

 small, not exceeding three or four feet, and did not extend below the point where the lava first reached the surface. 



'"This has been the case for some eight months. At first the whole ridge of the mountain was lighted with 

 fusion on the surface ; afterwards no fire was seen except at the end of the stream near Hilo [Note by Mr. Coan]. 



[451] 



