“And that is?” asked Midshipman Stark.
“To rise again, to be sure,” struck in the inventor.
Up in the conning-tower the boys could hear the conversation below distinctly.
“Hammocks and humming birds!” gasped Herc, “blessed if I hadn’t quite forgotten about the rising part of it.”
“It’s quite important, though,” said Ned, with a dry smile.
“Above there!” came a sudden hail from below in Lieutenant Parry’s voice.
“Aye, aye, sir!” bawled back Ned.
“Do you understand how to work the air-changing device?”
“Aye, aye, sir.”
“Then set it in motion, please. We wish to test how quickly we can get a fresh supply.”