"No, but the air is not as fresh as it should be," replied the inventor. "Washington, release a little more of the supply from the compression tanks."
The ship, which had been left to steer itself automatically while the professor was absent from the conning tower, was moving along at about half speed. The gage showed they were going at twenty miles an hour, and were three hundred feet below the surface.
"Washington and I will share the first night's watch between us," said the inventor, after the supper things had been cleared away. "There will not be much to do, as the ship will steer automatically in whatever direction I set her. Still I want to see how she behaves. The rest of you might as well go to your bunks."
The two boys were especially glad of a chance to go to bed, as they had had but little sleep the night before on account of the fire. So they lost no time in undressing and rolling up in the blankets, for it was quite cool so far down under the water.
"Well, we've slept on the earth, above the earth and now we're under the waters," observed Jack.
"There's only one place more to spend your time taking a snooze," said Mark.
"Where's that?"
"Inside the earth."
Then they fell asleep. During the night and the next day the Porpoise forged on underneath the waves. Washington relieved Mr. Henderson in the conning tower and reported the machinery to be working well.
"Keep her headed due south," was the order of the inventor, and the colored man did so.