of the crew?" asked the inventor, after
some further conversation.

"You can count on me!" cried Bill.

"And if Bill goes I'll go too!" exclaimed Tom.

"Under the seas or over the seas, it'll be all one to us if Professor
Henderson sails the ship!" went on Bill. "We'll go!"

"Good!" ejaculated the professor. "You certainly came at just the right
time."

As Tom Smith and Bill Jones were hungry a hasty meal was prepared for
them, during the eating of which they told of their experiences since
landing from the airship. They had been on a farm until fired with a
desire to go roving once more.

For the next few days the professor, the boys, and the other four were
busy making some improvements to the _Porpoise_. Tom and Bill were much
astonished at their first sight of the queer craft, but they soon became
accustomed to her, and said they preferred her to the airship.

"To-morrow we are going on a little longer trip than our first trial,"
announced the inventor one evening. "We will be gone all day if nothing
happens to make the stay more lengthy," he added grimly. "So,
Washington, put plenty to eat aboard."

A little later, when supplies had been put on the _Porpoise_, and the
machinery well overhauled, the professor explained that he intended
making a trip, entirely under water, from the dock in the cove to a
point off the Massachusetts coast and return.

Early the next morning all were aboard. To each one was assigned a
particular station. Washington, with Mark as an assistant, was in the
engine-room. Jack was to watch the various gages and registers to give
warning of any danger. The professor, of course, would be in the conning
tower and operate the craft. Andy was to be with him, to watch out, with
his sharp eyes, for any danger that might loom up in the path of the
searchlight. Tom and Bill were to be ready to help where needed.

With a hissing sound the water filled the tanks and the _Porpoise_ sunk
beneath the waves. The engine that worked the endless screw was
started, and the threads, working on the water cable, shot the boat
ahead.

"We're off!" yelled Washington.

About sixty feet below the surface the craft was sent along. Mile after
mile was covered as shown by the patent log. The lights were turned off,
and through the thick plate glass windows the strange inhabitants of the
sea were observed.

"I think I'll go a little nearer the surface," said the professor to
Andy. The inventor started the