For an instant the two young men hesitated. It was a new proposition to them. Yet they recalled that they had come safely back from the journey through the air.
"Do you want to go along as part 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.