He turned several levers. There was a hissing sound as the gas rushed
from the container, and the ship began to settle down.

"What's th' matter? Are we goin' t' hit th' earth?" yelled Washington,
rushing from the engine room.

"Keep quiet," ordered the professor. "We are only going down, that's
all."

"But good land! Perfesser!" exclaimed the colored man. "The ocean's
right under us! You forgot you sailed sway from the island! We'll be
drowned suah!"

"Leave it to me," said Mr. Henderson. "The Flying Mermaid is going to
take a bath!"

"As long as it swims it will be all right," observed Mark in a low
tone to Jack. "I'm glad I can take care of myself in the water."

Before Jack could reply the Mermaid seemed to take a sudden dive
through the air. The next instant she struck the water with a splash
that sent the waves rolling all about. The craft rocked violently to
and fro on the surface of the sea. For a while there were anxious
hearts aboard, for there was no certainty but that the ship might not
sink to the bottom.

But the old professor had not calculated and builded in vain. After
rocking about like a vessel newly launched, the strange craft rode
safely and upright on the water. It set down far enough to bring the