"I have another reason for this careful examination," remarked the Professor, as he was intently engaged in making notes on the board tablets. "It may be likely that the chamber has more than one outlet and if so, we must explore it also. Of course, I am most interested in the outlet to the south."
A circuit was made until they reached the outlet to the south, which Harry had discovered when the light on the ledge disappeared. The water throughout the cavern within the chamber was not over eight feet deep, and at the outlet to the south he could not touch bottom with the twelve-foot pole they carried. This outlet was contracted, and, judging from the width of the boat, could not be more than eight feet across, but it gradually widened, and the waters became shallower as they advanced.
George, who was in the bow, held up his hand as a warning. "Stop!" was all he said. All peered forward. The lights threw their beams forwardly through a broadening channel, beyond which appeared to be white forms ranged along the opposite wall.
"What depth have you, Harry?" asked the Professor, without seeming at all concerned.
"About five feet."
"Move straight ahead, until I tell you to stop."
The pole was thrust down and the boat moved forwardly fully fifty feet before a halt was called.
"I think we are now in the middle of this chamber. Before exploring it let us make a thorough examination of its characteristics."
"Look at those wonderful icicles hanging from the roof!" George gazed on them with wonder and admiration. Harry, on the other hand, with the utilitarian idea in his mind, inquired: "Why couldn't all that chalk be utilized for making plaster?"