He braced himself to the utmost, took a long breath, and then sprang.

His fingers caught on the ledge of stonework, and, with a desperate effort, he drew himself up, aided by his feet.

He had, before making the attempt, removed his boots, partly to avoid the scraping noise which these would make, partly to enable him the better to avail himself of the inequalities in the stonework.
It was a desperate struggle; and when he got his shoulders in the opening, which was just wide enough to admit them, he lay for three or four minutes, panting heavily, with the perspiration streaming down his face.

The aperture was too small to admit of his turning in any way, and there was nothing for it, as he knew, but to drop head foremost.
Gradually, he drew himself through the opening, lowering himself as much as he could by holding on to the upper edge by his feet.

Then, stretching out his arms to save himself, he let go.