Chapter XX. The Devil Fish

It was true. The long sinuous strands of ocean grass, known under the name of "serpent weed," had caught around the whirling propellers and there had been wound and twisted very tightly. Just as sometimes the stern line gets so tightly twisted around a motor boat propeller as to require hours of work with an axe to free it, the seaweed was twisted around the blades of the M. N. 1.

Slowly the undersea craft came to a stop, and there she remained, floating freely enough, but a few feet above the bottom of the ocean. There was a look of alarm on the faces of Ned and Mr. Damon, but Tom Swift smiled.

"This is annoying, and may cause us delay," he announced, "but there is no danger."

"How are we to get free from the weed?" asked Mr. Damon. "We can't move if it's wound around our propellers, can we?"

"Not very well," Tom answered. "But all that will have to be done will be for some of us to put on diving suits, go out and chop the strands of weed away. We can do it more easily than could an ordinary vessel, for they would have to go into dry dock for the purpose. I think I'll go out myself. I want to look around a little."

"I'll go with you," said Ned. "As long as we haven't seen any sharks I don't mind."

"Nor gigantic starfish, either," added Tom with a smile, and Ned nodded in agreement.

"We might try reversing the propellers," suggested the man from the engine room, who had come in with the information about the serpent weed. "The chief didn't like to try that. We saw the weed from our observation windows and stopped as soon as we felt we had fouled it."

"That was right," commended Tom. "Well, try reversing. It can't do any harm, and it may make it easier for us to free the propellers when we go out."

He went to the engine room himself to see that everything was properly attended to. Slowly the motors were reversed, and only a slight current was given them, as, with the resistance of the tightly wound weed, too powerful a force might burn out the insulation.

Slowly the starting lever was thrown over. There was a low humming and whining as the current jumped from the batteries, and a slight vibration of the craft. Tom looked at the movable pointer which showed the speed and direction of the propellers. The hand oscillated slightly and then stopped.

"Shut off the current!" cried Tom. "It's of no use. The propellers are held as tight as a drum! We've got to go out and cut loose the serpent weed!"

The experiment of reversing the propellers had failed. But still Tom did not believe his craft was in danger. He gave orders for the engine room force to stand by and then arranged for himself, Ned, and Koku to go outside in diving dress and cut the weed off the shafts.