propelling tubes well under, but not so far but that the conning tower
was well out and there was a small deck available.

"Now to see if we can conquer the water as we did the air!" cried the
professor. "Mark, start the air pump. Jack, you steer, for I want to
watch the machinery under the additional strain."

From the rear tube rushed such a volume of air that the ocean near it
bubbled and foamed. The ship trembled from stem to stern, and then,
after hanging for an instant as if undecided what to do, it began to
move forward as easily as though it had never sailed any other element
than the sea.

"She fits her name!" the professor cried. "She is indeed the Flying
Mermaid, for she sails the ocean as easily as she navigates in the
clouds!"

For a mile or two the craft was sent ahead over the waves. Then it was
reversed and run backwards. Satisfied that his long months of work had
not gone for naught, the professor after trying several experiments,
decided to try and raise the ship while in motion.

With Jack and Mark to look after the air pumps, while Washington, Tom
and Bill busied themselves in the engine room, Mr. Henderson began to
generate the gas and start the negative gravity apparatus. All the
while the craft was forging ahead.

There was again the hissing sound that told of the aluminum holder
being filled. For a few minutes there seemed to be no change, the
Mermaid plowing forward.