"We meant it," smiled the builder. "But say, the air is getting a bit foul here, isn't it? We'll have to try the compressed air equipment, now."
By an ingenious mechanical contrivance the present air was forced, by compressed air draught, into compartments from which the bad air was expelled through sea-valves. An instant change for the better in the atmosphere was noted.
"That's another thing about this good old new craft of ours that works all right, so far," remarked the builder. "Boys, I'm beginning to have confidence that we're going to see the surface again all right. Hullo, there's Pollard hailing us."
"The air purified all right, didn't it?" called down the inventor.
"Yes; couldn't have been better," declared the builder heartily.
"Then I'm going to make the supreme test," came down from the man at the wheel. "We'll proceed to find out whether we can rise to the surface and stay there."
CHAPTER XII
THE DISCOVERY FROM THE CONNING TOWER
"Go up slanting, or on an even keel?" called up Mr. Farnum.
"On the even keel," came the answer.