He had turned and twisted so much in his descent that it took him some time to decide in which direction the sea might lie and in which the rock.

And, having settled that, he wriggled through a crevice and wormed slowly on.
He was almost in the dark now, and could only feel his way.

But he was used to groping in narrow places, and a spirit of investigation urged him on.
Half an hour's strenuous and cautious worming, and a thin trickle of light glimmered ahead.

He turned and worked his way back at once.
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.