Luckily, his feet were not in a like plight, so that, after a time, he made shift to rise, and, with manacled hands outstretched before him, feel his way about his prison.
As nearly as he could judge, his cell was about four yards in length by rather less than half this in width. Its rock walls, rough-hewn and rugged for the most part, were, in one particular place, smooth as glass.
Carefully Mervyn passed his fingers over this slab, suspecting that it was the door to his cell yet not a crack could he find.
The rock there seemed not less solid than elsewhere. Again and again he tried, but never with the same result.
As the hours dragged by, and no one came to him, the scientist began to think that his captors had forgotten his existence.
Whoever they were, whatever they were, they surely could not intend him to be entombed alive? They would scarcely have troubled to chain him had they meant him to be shut away here for ever.
So thinking, Mervyn raised his voice in a shout.
The sound rang round the walls of his prison in an appalling uproar, yet apparently it was unheard without.
Allowing some moments to elapse, he repeated his effort.
The cell rang again with his cry, but still there came no answer, and at last he flung himself down upon the floor again.