ft the vicinity of the
savages far behind. After about an hour's flight the professor had Jack
lower the craft to within half a mile of the surface, as he said he
wanted to see what was below.

The boy, who was in charge of the conning tower, set the necessary
machinery, while the professor went to the window in the bottom of the
ship to watch.

"We're over the sea!" he exclaimed. "There is no land or ice in sight!"

"Come here quick!" cried Washington, from the engine room.

"What's the matter?" exclaimed the professor.

"De gas machine am gone on a rampage ag'in!"

Then, all at once, the airship began to sink. All rushed to the engine
room. The gas generator had ceased working and the craft was settling
toward the ocean, there being nothing to keep it aloft.

Frantically the professor and Washington worked at the apparatus. It
could not be adjusted. Despair was on every face. Faster and faster sunk
the _Monarch_.

"Will we sink?" asked Andy. "I can't swim."

"We may float," said the professor. "The bottom part of the ship is
water tight. We may float long enough to fix the machinery."

Then, with a splash, the _Monarch_ settled into the ocean, the gas bag
falling limply on top of the cabins.

"Get out the life preservers!" shouted the professor. "They are in the
forward part. Put them on, while Washington and I try to fix the gas
machine!"

The airship had now become a water ship. It rose and fell on the waves,
rocking from side to side.

"Get ready to jump!" yelled Jack, running in from the conning tower.

"What now?" asked Professor Henderson, "Haven't we troubles enough?"

"There's a big whale and he's headed right this way!" yelled Jack. "He's
coming on like a locomotive, to ram us!"

Andy caught up his gun and hastened to the tower. As Jack had said, a
big sperm whale, spouting water high in the air from his nostrils, was
headed for the _Monarch_, which, as it lay on the surface, the whale
evidently took for a rival.

"I wonder if I can stop him with this rifle," exclaimed Andy.

"No, but you can with the machine gun!" said Jack.

"Not while it's in the stern," replied the old hunter. "I guess we are
done for this time. I'll fire a few shots, anyhow, before I die!"

"Wait!" yelled Jack. "I'll turn the ship around!"

"Can you do it?"

"I think I can," was the short reply.

"We cannot use the machinery."

"I know that, but I can use something else--that is, I think I can."

"There is