"KEEP the doors closed!" cried the professor. "It is our only hope! I will send the ship up again!"

But it was too late. Washington, who had obeyed the signal from the conning tower to shut off the engines, had disconnected most of them so they could not be started again save from the main room. At the same time there came a yell of dismay from the colored man, who had slid back the steel covering of the main side entrance to the Mermaid.

"I'm caught!" cried Washington.

As the professor and the boys hurried from the tower, they could hear a struggle from where Washington was, and his voice calling:

"Let me go! Let me go!"

Reaching the engine room, which opened directly on the side entrance, the professor saw a pair of enormous hands and arms dragging poor Washington, feet first, out of the ship. Bill and Tom were crouched in one corner, pale with fright.

"Wait until I get my gun!" cried Andy, as he ran for his rifle.

"Hold on!" called the professor in a loud voice. "It will be folly to shoot them! We must try strategy!"

Washington's cries ceased as he was drawn entirely from the ship, the giant hands disappearing at the same time.

"Follow me!" yelled Mr. Henderson, running out of the door.

Hardly knowing what they did, the boys went after him, and their hearts almost stopped beating in fright as they saw the terrible things, which, in the glare of the changing lights, were on every side of them.

For the men were very repulsive looking. They there attired in clothes, very similar in cut to those worn by the travelers, and which seemed to be made of some sort of cloth. But they were loose and baggy and only added to the queer appearance of the giants. Veritable giants they were too. Their faces seemed as large as kegs, and they were so clumsy in shape that Mark, even, frightened as he was, exclaimed:

"They look like men made of putty!" At the same time he saw they bore a resemblance to the creature he had observed on the hill top.

"What shall we do?" asked Andy of the professor. "They are really carrying Washington away!"

Three of the giants were dragging the colored man along the ground, while the other terrible beings stood about as if waiting to see the outcome of the first sally.

"I will try to speak to them," Mr. Henderson said. "I know several languages. They may understand one."

But before he could start on his parley a surprising thing happened.

There was a struggle in the little group about Washington. The colored man seemed to be fighting, though the odds, it would appear, were too great to enable him to accomplish anything. But, making a desperate effort to escape, Washington quickly wrenched himself free from the giants' hands and then, striking out with his fists, knocked the three down, one after another.

"I never knew Washington was so strong!" exclaimed Jack.

"Nor I," put in Mark. "Why I should think the men could carry him in one arm as if he was a baby."

The three giants rose slowly to their feet. They uttered strange cries, and motioned with their hands toward the professor, the boys, and the others in the crowd.

"Look out! They're goin' t' grab yo'!" cried Washington.

Three of the giants approached Mark, and a like number closed in on Jack.

"Back to the ship!" cried the professor. "We must defend ourselves!"

But by this time the big men had grabbed the two boys. Then a strange thing took place. Mark and Jack, though they felt that the giants must overcome them in a test of strength, struggled with all their might against being captured. They fought, as a cornered rat will fight, though it knows the odds to be overwhelming. But in this case the unexpected happened.

Both boys found they could easily break the holds of the giants, and Mark, by a vigorous effort, pushed the three men away from him, one at a time violently so that they fell in a heap, one on top of the other.

"Hurrah! We can fight 'em!" cried Mark. "Don't be afraid. They're like mush! They're putty men!"

And, so it seemed, the giants were. Though big in size they were flabby and had nothing like the muscle they should have had in proportion to their build. They went down like meal sacks and were slow to rise.

Jack, seeing how successful his comrade was, attacked the three giants who were striving to make him a captive. He succeeded in disposing of them, knocking one down so hard that the man was unable to rise until his companions helped him.

"That's the way!" cried Washington. "They're soft as snow men!"

The vanquished giants set up a sort of roar, which was answered by their fellows, and soon there was a terrible din.

"All get together!" called the professor. "They are evidently going to make a rush for us. If we stand by one another we may fight them off, though they outnumber us a hundred to one. Besides it will soon be dark, and we may be able to escape!"

Washington, Jack and Mark retreated toward the ship, in the direction of which the others had also made their way. The big men had gathered in a compact ma.s.s and were advancing on the adventurers.

"What do you suppose makes them so soft?" asked Mark. "I believe I could manage half a dozen."

"It must be the effect of the climate and conditions here," the professor replied. "Probably they have to be big to stand the pressure of the thick water, and the increased attraction of gravitation. Then too, being without the weight of the atmosphere to which we are accustomed, they have probably expanded. If they were to go up to earth, they might shrink to our size."

"Do you think that possible?"

"Of course. Why do you ask?"

"Nothing in particular," replied Mark. But to himself, he added: "That would explain it all."

It was getting dusk now. The travelers had reached their ship, and rushed inside and tried to close the doors in the face of the advancing horde. But, by this time the giants were so close that one or two of them thrust their big feet in, and prevented this movement.

At the same time they set up a great howling.

"Quick!" cried the professor. "We must start the ship and get away!"

"I can't close the door!" yelled Washington, who had been the last to enter.

"Never mind that! Go up with it open! Drag them along if they won't let go!" answered Mr. Henderson, as he ran toward the engine room.

There was a sudden rush among the giants, and a sound as if something was being thrown over the top and ends of the ship. Mark turned the gas machine on, while Jack worked the negative gravity apparatus. They waited for the ship to rise.

"Why don't we go up?" asked the professor.

"'Cause they've caught us!" called out Washington.

"Caught us? How?"

"They've thrown ropes over the top and ends of the ship, and fastened them to their big houses!"

Running to a side window the professor saw that the Mermaid was fastened down by a score of cables, each one six inches thick. They were held captives by the enemy.