But there were other things to think of first. Principally, there was that important discovery to make whether they were surrounded by the sea, and to try and find this out he sought a higher point than any he had yet mounted, and, taking out his little glass, followed the face of the mist till it reached the glittering waters of the sea, and then tried to trace the coastline towards the volcano.
This he was able to do with pretty good success, but as his glass was directed to the lower and eastern slope of the mountain, he found that he was as wise as ever, for the base of the mighty cone completely shut off all view in that direction.
Turning to the mist again, he followed its edge to the west as far as he could reach, but the inequalities in the surface baulked him here, and he could not make out the sea in that direction.
He closed his little glass and turned to the mist curtain, that mysterious dim line glistening with opalescent colours, and determined as a last resource to walk quietly as close to it as he could, before the gases began to affect him, then to draw back a few yards, take a few deep inspirations, so as to fully inflate his lungs, and then rush straight through; for he argued to himself, if he could pass through once unprepared and taken by surprise, he could certainly reverse the action.
In this spirit, and so as to get a little encouragement and inspiriting for another task—in other words, so as to enjoy the feeling that a way of retreat was open to him—he walked back toward the depression along which the vapour rose, examining every step of the way, and noticing that by degrees all growth ceased as he approached, and that the ground gradually grew softer and then spongy to the tread, as if he were walking over a bog.
The air remained very clear and good to breathe as he went on nearer and nearer, seeing now that the fumes rose softly all along one jagged line such as might have been formed by the earth opening right before him. But there was no opening. As far as he could penetrate the dim mist, the earth looked perfectly level, but the vapour rose from it as it does or appears to do from a swampy meadow on a fine autumn evening; and it was evident to him that he might try and dash through without fear of running headlong into some chasm.
Just then, as he stood gazing down at the bottom of the curtain, the idea struck him that perhaps there had been a wide rift right across to right and left; that it had been filled up by volcanic matter, and the vapour was caused by this lava or hot liquid mud slowly cooling down.
Convinced that this must be so, he had full endorsement of the correctness of his theory, for on lifting one foot to go on, he found that the other was sinking slowly, and a little further investigation showed him that a faint thread of vapour was rising from the spot where his heel had been.
The meaning of this barren space, and the reason for the earth feeling spongy, was plain enough now, and he knew that he was walking over so much half-fluid volcanic pitch, whose surface was slightly hardened and formed the elastic springy band.
If it gave way!