Huge and forbidding, of all shapes and sizes, the mighty fragments barred his course like a menace, and he attacked them warily, drawing himself with infinite caution from one to another; over this one, under this, deftly between these two, lest an unwary weighting should start them on the movement that might grind him to powder.
The fog increased their forbidding aspect tenfold.

He could not see a foot before him, and could only worm his way among them, testing each before he trusted it, and finding at times monsters become but mediocre when his hand was on them.

More than once he had to rest his hands on cautiously-tried ledges and swing his legs forward and grope with his feet for foothold, and whether the space below was trifling, or whether it ran to incredible depth, he could not tell.
It was a mighty relief to him to come out at last on the other side of the wall, and to find himself on the great north slope which faced Sark, and so was closed to him in clear weather.
The long thin grass grew rankly here, and was beaded with moisture, but he pushed along with an eerie feeling at the wildness of it all.
The mist clung close about him, but had suddenly become luminous.

He felt as though he were packed loosely all round with cotton wool on which a strong light was shining.

It gave him a feeling of light-headedness.