ght you said your submarine was safe for underwater trips!" he
fairly snapped at Tom.

The young inventor gave one look at the irate man who was coming out in
his true colors. But it was no time to rebuke him. Too much yet
remained to be done. Ned and Koku were still in the chamber and
protected from some unknown sea monster by only a comparatively thin
door. They must be inside to be perfectly safe.

Tom speeded up the pumps that were forcing the water from the chamber
so the inner door could be opened. Eagerly he and his men watched the
gauges to note when the last gallon should have been forced out by the
compressed air. Not until then would it be safe to let Ned and Koku
step into the interior of the craft.

The submarine had not ceased rolling from the force of the blow she had
received when there came another, and this time on the opposite side.
Once more she rolled to a dangerous angle.

"Bless my tea biscuit!" cried Mr. Damon, "what is it all about, Tom
Swift?"

"I don't know," was the low-voiced answer, "unless a pair of monsters
are attacking us on both sides alternately. But we'll soon learn. There
goes the last of the water!"

The gauge showed that the diving chamber was empty. Quickly the inner
doors were opened, and, with their suits still dripping from their
immersion in the salty sea, Ned and Koku stepped forth. In another
moment their helmets were loosed from the bayonet catches, and they
could speak.

"What was it, Ned?" cried Tom.

"Big fish!" answered Koku.

"Two monster whales!" gasped Ned. "We barely got away from them!
They're ramming the sub, Tom!"

As he spoke there came a blow on the port side, greater than either of
the two preceding ones. Those in the M. N. 1 staggered about, and had
to hold on to objects to preserve their footing.

"Both at the same time!" cried Ned. "The two whales are coming at us
both at once!"

This was evidently the case. Tom Swift quickly hurried to the engine
room.

"What are you going to do?" asked Mr. Hardley. "You ought to do
something! I'm not going to be killed down here by a whale. You've got
to do something, Swift! I've had enough of this!"

Tom did not deign an answer, but hurried on. Mr. Damon followed him,
having seen that some of the sailors were helping Ned and Koku out of
the diving suits.

"Are we in any danger, Tom?" asked the eccentric man.

"Yes; but I think it is easily remedied," was the answer. "We'll go up
to the surface.