"It is not likely that the same spring does double duty. We will have to hunt up the other," said Harry. "Now, by all the laws of symmetry there should be another similar stone on the other side of the slab—and here it is."
He pushed on this as he spoke, and at once the grinding sound began again and the stone slowly settled back into place.
"Well, our discovery of the Don's secret inquisitorial passage does not appear to have done us much good," said Bert, as they stretched themselves out on their beds again.
"I'm not so sure of that," replied Harry, thoughtfully. "I think I see a way by which at least one of us three can benefit by it."
"How?"
"Wait until I get it all thought out. In the meantime I am going to get a little more sleep."
They did not return to their own cell any too soon, for they had no more than turned over for their second nap when a light flashed in their eyes and they sat up to find their silent jailor had opened the door noiselessly and was inspecting the room with the aid of a large lantern. He nodded his head in a satisfied way and passed out again.
"Say, Hal, old man, this sort of thing is getting on my nerves," said Bert, when the man had gone.
"I wouldn't mind a few streaks of daylight myself, Bert."
Tired as they were, the boys' nerves were so worked upon that they were unable to go to sleep again and tossed on their cots until the gray dawn began to show through the windows. They lay in a sort of lethargy watching the sky grow brighter and brighter until they were aroused to action by the loud voices of men and the clanking of guns in the jail yard below.