A faint sound of unbarring came from behind the door, which quickly opened, and they dodged into the room.
As yet there was no light in the room, and, still filled with wonder, Frank asked:
"Was that the regular sentinel out there, Bart?"
"That was our sentinel," was the reply.
"But where are the regular sentinels? I did not see one of them."
Faint chuckles came from several parts of the room, and Hodge replied:
"At a certain hour each night the duties of the regular sentinels take them away long enough for me to get out of my room and in here. See?"
"They must be in the trick?"
"The most of them are. When it happens that one is not, we have to look out for him, and dodge him. To-night those on duty on this floor were all fixed."
Then somebody cautiously struck a match, by the flare of which Frank saw several fellows were gathered in the room.