Chapter 92
"Not much to see, Ned," said Jack as the man joined him. "That must be where the bright glow comes from at night."
He pointed down over the dark silvery grey waste, dotted with stones of all sizes, to where a pool lay on one side, apparently of water, for a s.h.i.+mmering light played over it, and a faint mist was rising slowly into the air.
"Couldn't come from water, sir," said Ned. "I didn't expect to see a pond up here; but I suppose it's hot, and that's steam."
"Oh yes, that's hot enough," said the doctor, who was panting with his exertions. "Liquid fire, eh, Jack?"
"Wouldn't it be molten metal of some kind, father?" cried the boy.
"No, my lad, it is molten stone--rock. Lava."
"But it puzzles me," cried Jack, "how stone can melt. You said something to me one day about a flux."
"Yes, of course. People who smelt metals found that out long enough ago, and it is the same with making gla.s.s. If you expose some minerals separately to great heat they merely become powder; but if you combine them--say flinty sand with soda or potash--they run together and become like molten metal. I believe if ironstone and limestone are mixed, the ironstone becomes fluid, so that it can be cast like a metal--in fact becomes the metal itself."
"Then that pool down there, if emptied out, would run like the volcanic gla.s.s we have found below?"
"Most likely."
"Let's go down this slope so as to see the pool from nearer."
"Rather a risky proceeding, my boy," said Sir John; "suppose we were to break through."
"Break through? Why, you don't think it is hollow under here?"
"I should rather believe that there was a stony crust hardened by cooling, and that a very short distance beneath us the rocks are all molten."
"But all these great stones lying about don't break through. Let's go a little way down."
"Don't be rash then. Will you come, Instow?"
"Oh yes, if it's safe. Let's go cautiously."
Just then the sailors, who had had to pack up and carry the camping-out necessaries, appeared at the edge, and waited there watching the little party as they slowly descended toward the s.h.i.+mmering pool, threading their way in and out among the blocks of lava and pumice which lay in their road.
Sir John led, with Jack close beside him, and the doctor and Ned followed a little way behind, to their right. But they had not descended a hundred yards before Sir John stopped short.
"No farther!" he said. "The heat is getting intense, and overpowering gases are escaping from the ashes. We must go back, Jack."
"I suppose so," said the lad unwillingly. "We don't see the pool any the better for being here either. Oh, look at that!"
There was no need to call attention, for all were startled by a sudden report, and a glow of heat swept past their faces as a huge fountain of fire suddenly played up some sixty or seventy feet like a geyser, and fell back with a heavy splash, lower and lower, still playing till there was only a slight eminence, as if bubbling in the middle of the pool.
Then it was perfectly level again, and a cloud of white
"That would have been grand by night," shouted the doctor.
"It was grand now," replied Sir John.
"Well, I think we had better turn back," said the doctor. "There is no doubt about its being molten fire below here, for the heat gets fiercer.
Look."
He had been resting on the climbing pole he brought up with him, and found that the end had gone down a couple of feet, while as he drew it out the point was charred and smoking.
This induced Sir John and Jack to do the same, and theirs were burnt as well.
"Yes, get back at once!" shouted Sir John in startled tones. "Quick, all of you; our weight is acting upon the ashes, and they are gliding down with us."
"Hi! look out below, gen'lemen," shouted Lenny from the edge, "that there's bending like thin ice."
The warnings were none too soon, for as the pair turned sharply and began to climb back, it was quite plain that though the blocks of stone about lay or half floated upon the ash-covered surface, any further weight was sufficient to produce a change, and before they had taken many steps, one huge ma.s.s not twenty yards from Sir John was seen to be sinking slowly, then faster and faster, and disappeared through the ashes, which changed rapidly to a s.h.i.+mmering fluid, and sent forth a terrible heat.
"Don't hurry--open out slowly so as to spread the weight!" cried Sir John; and the doctor and Ned obeyed; but Jack saw that at every step his father's feet sank lower, and that his alpen-stick gave him no support, but went right in.
"Do you hear me, Jack?" shouted Sir John.
"Yes, father, but I can't leave you," cried the lad. "Here, give me your hand, or take hold of the end of my staff."
"Go on! Obey me, boy, or you will destroy us both," cried Sir John sternly, and Jack continued to climb up the slope, finding it more and more yielding, and as if below the ashes and stones there was a quivering or bubbling going on.
"That's right! go on, Jack; go on," cried Sir John. "It isn't far now."
They pressed on with a horrible feeling of panic attacking them now, for the quivering beneath them increased, the surface over which they toiled was trembling, and several of the blocks they pa.s.sed began to settle slowly down.
"Only another fifty feet!" shouted the doctor. "Come on."
But at that moment a yell of warning came from the sailors, and Jack looked round to see that the ashes where his father climbed up were changing colour; then he noted that the slope was growing steeper and steeper; and to his horror his father threw himself at full length and began to crawl.
"Below there!" yelled Lenny. "Look out, Sir John."
"Below there! look out, Mr Jack," cried another sailor; and a couple of ropes flew down the slope in rapidly opening rings, and so accurately pitched that Jack caught his just as he felt that he was sliding downward.
Before he could turn to look at his father the rope tightened, and he was rapidly drawn up out of a heat that was terrible; but as he reached the edge of the crater he wrenched himself round in time to see that Sir John was nearly up; and the next minute he too was well over the side, the doctor and Ned, who had reached the top unaided, coming up white and trembling.
It was none too soon, for a minute later the slope down toward the pool, which had been easy, had now become, from the sinking of the centre, tremendously steep, and the pool itself suddenly began to spread out more and more, till half the expanse below was covered with the s.h.i.+mmering molten lava, and the heat became so intense that they were all glad to retreat down the side.
"What an escape, my boy!" panted Sir John, as he grasped his son's arm.
"It was dreadful," whispered Jack. "But are you hurt?"
"Nothing much; a little scorched."
Sir John held up one of his feet, and Jack could see that the leather of the boots was crushed up and drawn out of shape, while this drawing his attention to his own feet, which he now felt were uncomfortable and strange, he saw that his heavy boots were wrinkled up in the same way.
But they had to hurry their steps down the mountain side, for an earthquake-like quivering made the earth feel as if a wave was running beneath them, while in quick succession two thunderous explosions came from below; huge stones were thrown high in the air, and could be heard falling back into the crater with an awe-inspiring sound.
There was no temptation to pause and watch what was evidently the commencement of an eruption, and which might at any moment grow in force, so every effort was made to reach the sh.o.r.e, as nearly as they could judge about the part of the island off which the yacht was expected to lie.
They were fortunate on hitting upon one of the ravines which scored the mountain side some time before noon, and after a brief halt for refreshment, pushed on down its precipitous sides hour after hour, for the explosions from the crater grew more frequent, and all felt that they might culminate in some terrible cataclysm that would overwhelm them all.