Somewhat against their will the three latter made the trip, for the professor did not want to return to earth with them.
The party had many adventures on the voyage, having to fight savage animals and more savage Esquimaux. They reached the north pole, but in the midst of such a violent storm that the ship was overturned, and the discovery of the long-sought goal availed little. After many hardships, and a fierce fight to recover the possession of the ship, which had been seized by natives, the adventurers reached home.
Since then a little over a year had passed. The professor, having found he could successfully navigate the air, turned his attention to the water, and began to plan a craft that would sail beneath the ocean.
To this end he had moved his machine shop to this lonely spot on the Maine coast. The two boys, who had grown no less fond of the old man than he of them, went with him, as did Washington White, the negro, who was a genius in his way, though somewhat inclined to use big words, of the meaning of which he knew little and cared less.
Andy Sudds, the old hunter, had also been induced to accompany the professor.
"I hunted game up north and in the air," said Andy, "and if there's a chance to shoot something under the water I'm the one to do it."
Needing more assistance than either the boys, Andy or Washington could give, the professor had engaged two young machinists, who, under a strict promise never to divulge any of the secrets of the submarine, had labored in its building.
Now the queer craft was almost finished. As it rested on the ways in the shed, it looked exactly like a big cigar, excepting that the top part was level, forming a platform.
The ship, which had been named the Porpoise, was eighty feet long, and twenty feet in diameter at the largest part. From that it tapered gradually, until the ends were reached. These consisted of flattened plates about three feet in diameter, with a hole in the center one foot in size.
Weary months of labor had been spent on the Porpoise, until now it was almost ready for a trial. The professor had discovered a new method of propulsion. Instead of propellers or paddle-wheels, he intended to send his craft ahead or to the rear, by means of a water cable.