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. There were
twin propellers on the submarine, each revolving independently by
separate motors, and each capable of being sent in forward or reverse
direction.

"Start the engines as soon as we give the signal," Tom told the
machinist. "Two knocks on the hull with an axe will mean go ahead, and
three will mean reverse."

"I understand," said Weyth, the machinist. "But stand away from the
propellers after you give the signal. I'll give you three minutes to
move clear."

"That will be enough," Tom said. "But better make it half speed in
either case. My idea is that if we can partly cut the weed off,
starting the propellers, either forward or in reverse, will finish the
trick."

"It may," agreed Weyth.

Armed with axes and sharp steel bars, Tom, Ned, and Koku were soon
ready to step outside the submarine.

They entered the diving chamber. In the usual manner water was
admitted, and, when the pressure was equalized, the outer door was
opened and they walked out on the floor of the ocean, the submarine
having been allowed to settle down again on the bottom of the Atlantic.

The powerful searchlight had been turned so that the beams were
diffused toward the stern. In addition to this Tom and his two
companions carried, attached to their suits, small, but brilliant,
electric torches. Of course they had their air tanks with them, and
also the telephones, by means of which they could communicate with one
another.

As they emerged into the warm waters surrounding the submarine they
disturbed thousands of small fish which were feeding all about. Like
ocean swallows, the creatures scattered in all directions, some even
brushing the divers as they slowly made their way toward the stern of
the craft.

"Nice place here," said Ned to Tom, as they walked along, Koku coming
just behind them.

"Yes