The progress of the front of the stream, owing to the ob structions of trees, depressions and irregularities, was very slow, not more than a mile per week. When there were obstruc tions the edge of the flow would become crusted, the lava behind would accumulate until the pressure became too great to be with stood, and then the liquid would burst through in a spurt and continue downwards till another set of obstructions caused an accumulation and another break allowed a discharge. Hence as one ascends any of the flows he seems to pass over a series of rough terraces.
Such a stream will also become widened by lateral discharge into a number of channels. After a free flowing for a while there may be much hardening of the crust and several days of in activity. "At length, immense areas of the solidified lava, four, five or six miles above the extremity, are again in motion ; cones are uncapped, domes crack, hills and ridges of scoriae move, and great slabs of lava are raised vertically or tilted in every direc tion." October 22, seventy-two days after the commencement of the eruption, the fountain still continued to flow. Mr. Coan made another trip—this time to the lower end of the stream. A river of water below had become discolored with the pyroligneous acid distilled from the burning trees and the water turned black. He attempted several times to cross the stream. "The hardened sur face of the stream was swelling and heaving at innumerable points by the accumulating masses and the upraised pressure of the lava below ; and valves were continually opening, out of which the molten flood gushed and flowed in little streams on every side of us. Not a square rod could be found on all this wide expanse, where the glowing fusion could not be seen under our feet through holes and cracks in the superincumbent stratum on which we were walking. The open pits and pools and streams we avoided by zigzag course ; but as we advanced these became more numer ous and intensely active, and the heat becoming unendurable we again beat a retreat after having proceeded some thirty rods upon the stream. It may seem strange to many that one should venture on such a fiery stream at all, but you will understand that the greater part of the surface of the stream was hardened to the depth of from six inches to two or three feet ; that the in candescent stream flowed nearly under this crust like water under ice, but showing up through ten thousand fissures and breaking up in countless pools. On the hardened parts we could walk, though the heat was almost scorching, and the smoke and gases suffocating. We could even tread on a fresh stream of lava only
one hour after it had poured from a boiling caldron, so soon does the lava harden in contact with air." Both Mr. Coan and Professor Dana are on record as saying that there must have been fissures far down the mountain from which lava issued, as well as from the source 12,000 feet high. The latter, however, does not speak of them in his latest de scription of this flow, so that it may be inferred that he had ceased to entertain that view.
March 6, 1856, Mr. Coan writes : "The great fire-fountain is still in eruption and the terminus of the stream is only five miles from the shore. The lava moves slowly along on the surface of the ground, and at points where the quantity of lava is small, we dip it up with an iron spoon held in the hand. During the last three weeks the stream has made no progress towards Hilo, and we begin to hope that the supply at the summit-fountain has diminished. There is, however, still much smoke at the ter minal crater." This hope became fact. The stream stopped at a point about five miles above Hilo.
Mr. Coan visited this flow eight times during its history. On the 22nd of October, 1856, he writes more fully about the sup posed fissures : "A fracture or fractures occurred near the sum mit of the mountain which extends in an irregular line from the terminal point, say five miles down the northeast slope of the mountain. From this serrated and yawning fissure, from two to thirty yards wide, the molten flood rushed out and spread laterally for four or five miles, filling the ravines, flowing over the plains,. and covering all those high regions, from ten to one or two hun dred feet deep. Along this extended fissure, elongated cones were formed at the points of the greatest activity. These cones, appear as if split through their larger diameter, the inner sides being perpendicular or overhanging, jagged and hung with stalactites, draped with filamentous vitrifications, and encrusted with sulphur, sulphate of lime and other salts.
"The outsides of these cones are inclined planes, on an angle of forty or sixty degrees, and composed of pumice, cinder, vol canic sand, tufa, etc. You will not, however, understand that these semi-cones were once entire and that they have been rent: they are simply masses of ridges of cinder and dross deposited on each side of the fractures where the action is greatest. It is all a new deposit. After you leave the region of open fissures, near the summit of the mountain, all below appears to be a flow on the surface." 20