By this time the ship had rushed past the whale, but the boys, looking
through a window in the rear of the tower could see the huge body. Now
the fountains of water which the whale spouted were tinged with red.

"He's bleeding!" exclaimed the professor. "I guess Andy hit him in a
vital spot."

"But not vital enough!" cried Mark. "See! He's coming after us!"

And so it proved. The whale, angered, and, probably half crazed by the
pain of the bullet and the blow, was coursing after the ship, coming
on with the speed of an express train. Straight at the Mermaid he
lunged his huge bulk.

"We must escape him!" cried Mr. Henderson. "If he hits us he'll send
us to the bottom!"

He had made ready to slow up the Mermaid to see if it had sustained
any damage from the impact with the whale, but when he saw the monster
coming after the boat he knew the only safety lay in flight.

"Let us go up into the air and so escape him!" cried Jack, with sudden
inspiration.

For an instant neither Mark nor the professor grasped what Jack meant.
Then, with an exclamation, the professor pulled forward the lever that
generated the gas and set working the gravity neutralizer, which would
enable the ship to rise.

Faster through the water went the Mermaid, and faster after her came