steered her about in a large circle, bringing her back to
the starting point. She worked as smoothly as if she had been used to
under-water service for years.

"Now," said the inventor, "we will see if we can go up to the surface
again," and there came a little note of anxiety into his voice. He
slowed down the engine and started the powerful pumps that were to empty
the tanks. For a moment there was a feeling of terror in the hearts of
all. Would the pumps work?

Then, slowly but surely, those aboard the _Porpoise_ felt her beginning
to rise. Up and up she went as the tanks were emptied and the ship
lightened.

Then, with a bounce like a rubber ball, the submarine shot upward to the
surface and lay undulating on the waves caused by her emergence from the
depths.

"Hurrah!" shouted Jack. "We're all right!"

"We shore am!" exclaimed Washington.

"It's a success!" Professor Henderson almost whispered. "The pumps
worked. The _Porpoise_ has fulfilled my greatest expectations!"

Then he steered the ship back to the dock, where she was moored, and the
adventurers disembarked.

"One or two little details to attend to, and we'll be ready for the
great trip," remarked the professor. "I want to give her a little harder
trial before I trust her, though she seems to be first-rate."

They all went back to the combined machine shop and cabin, where they
had lived during the building of the submarine. Dinner was prepared and,
after the meal the two machinists approached the professor.

"I don't suppose you need us any more," remarked Henry Watson. "The ship
is finished as far as we can do anything, and we may as well leave now.
We have an offer to go to work in an electrical shop."

"I haven't said much to you about my plans," the professor replied, "but
if you would like to remain in my employ, I can promise you an
interesting trip."

"Thank you, but I prefer to work above ground," said James Pensen. "You
have been very kind to us, and we would do anything we could for, but we
don't want to take any long under-ocean trips if we can help it."

"Very well," answered the professor, though he seemed disappointed. "I
will pay you what I owe you and you can go."

For some time after the departure of the two young machinists the
inventor seemed worried.

"Did you count on them staying with you?" asked Mark.

"I rather hoped they would," replied Mr. Henderson. "We need two more
hands if we are to make the trip. They need