There was no slit opposite the one he had tried, but presently, half-way up the well, he made out an opening like the mouth of a small adit. His back had been to it as he came down, and so he had missed it.
He climbed up and in, and felt convinced in his own mind that this was no simple work of nature. Nature had no doubt begun, but man had certainly finished it. For the floor level was comparatively free from harshness, and the outjutting projections of the sides and roof had been tempered, and progress was not difficult.
It was very narrow, however, and very low, and quite dark. He could only drag himself along on his stomach like a worm. But he pushed on with all the ardour of a discoverer.
Was it silver? Was it smugglers? Or what? Wholly accidental formation he was sure it was not, though he thought it likely that man's handiwork had only turned Nature's to account.
The fissure had probably been there from the beginning of time, or it might be the result of numberless years of the slow wearing away of a softer vein of rock, but some man at some time had lighted on it, and followed it up, and with much labour had smoothed its natural asperities and used it for his own purposes. And he was keen to learn what those purposes were.
To any ordinary man, accustomed to the ordinary amplitudes of life, and freedom to stretch his arms and legs and raise his head and fill his lungs with fresh air, a passage such as this would have been impossible. Here and there, indeed, the walls widened somewhat through some fault in the rook, bur for the most part his elbows grazed the sides each time he moved them.
Even he, used as he was to such conditions, began at last to feel them oppressive. The whole mighty bulk of L'Etat seemed above and about him, malignantly intent on crushing him out of existence.
He knew that was only fancy. He had experienced it many times before. But the nightmare feeling was there, and it needed all his will at times to keep him from a panic attempt at retreat, when the insensate rock-walls seemed absolutely settling down on him, and breathing was none too easy.
But going back meant literally going backwards, crawling out toes foremost; for his elbows scraped the walls and his head the roof, and turning was out of the question. The men who had made and used that narrow way had undoubtedly gone with a purpose, and not for pleasure. And he was bound to learn what that purpose was.
So he set his teeth, and wormed himself slowly along, with pinched face and tight-shut mouth, and nostrils opened wide to take in all the air they could and let out as little as possible. And, even at that, he had to lie still at times, pressed flat against the floor, to let some fresher air trickle in above him.