For a few seconds there appeared to be no result, then, almost without warning, the stone gave quite a couple of inches, till it was flush with the adjoining slabs.
Detroit felt it rise. Desperately he wrenched at it with his bare hands. Hamerton, rolling over on his back, pushed as hard as he could with his foot. The next instant he felt the American's sinewy fingers grasping him by his toes.
"Chuck it, old man!" whispered the Sub. "That's my toes you've got hold of."
"Guess I don't care, so long as I've got hold of some part of you," was the glad response. "Let's have your hand, then."
It did not take very long for the hole to be enlarged sufficiently to allow Hamerton to enter the American's cell. By a sheer piece of luck the aperture bore the same relative position to the floor as did the one in the adjoining room. It was almost in the corner, where, in the daytime, by contrast with the light filtering through the window, it was almost dark.
For some considerable time the reunited comrades whispered in tense, excited tones, their conversation being the outcome of joy rather than the discussion of a definite plan of action. But by degrees they grew calmer, and Detroit asked what the next move was to be.
"Get out of this show as soon as possible," announced Hamerton with determination.
"And then? We are not paladins; we cannot hope to overpower the whole garrison. There are sentries at every few yards; every boat is guarded. We will have to remain hidden on this little rock till hunger compels us to give ourselves up."
"We'll risk that. In almost every enterprise there is an element of chance that oft leads to success. Once we break out of this place we'll have a good look round. They've condemned me as a spy, and, by Jove, I'll do a little espionage!"
"And I'll have a shot at it," added Detroit. "Who knows but that some day the United States Navy may be glad of certain information concerning this island."