Chink

Yet he will find a chink or two

Then it was withdrawn as suddenly as it appeared, and all was dark again save the single lurid spark which marked a chink between the stones.

Evidently, as they had dragged the stone up they had thrust the chunks of wood into the chink, until at last, when the opening was large enough to crawl through, they would hold it open by a billet placed lengthwise, which might very well become indented at the lower end, since the whole weight of the stone would press it down on to the edge of this other slab.