XIX

MACKINDER AGAIN

Even as the five boys glanced at each other with startled and wondering
looks, the thumping ceased abruptly. In a short space it was resumed.
Instinctively the boys gathered near the spot.

While they stood there trying to determine the cause for the strange
procedure, the noise ceased. They heard a tapping at one of the
portholes. Jimmie rushed across the compartment to investigate.

"Hey, fellows, come over here a minute!" he called out.

"What have you found now?" questioned Ned, obeying the request.

"Here's this chap, and he's making all sorts of signals!"

"That's funny!" puzzled Ned. "Can you make out what he wants?"

"He's making his hands go in the strangest way! I'm sure I can't
interpret such motions unless he wants us to turn around while he places
a bomb or something close enough to blow us out of the water."

"I know what he wants!" shouted Harry, who had been closely observing the
stranger's repetition of the strange motions. "He wants us to open the
valve leading from that sea cock where he has been working!"

"Fine business!" scorned Jimmie. "Open up the sea cock and let the ocean
come running all over our nice carpets! I guess not!"

"I'm going to try it, anyway!" declared Harry. "If a little water does
come in, the pumps will take care of it before it becomes dangerous. At
least, it's well worth trying!"

"Go ahead, then, but don't blame me if anything happens!"

Harry moved to the vicinity of the spot where the stranger had been
occupied but a few moments before. Jimmie was at the porthole.

A turn of the valve resulted in a sudden short inrush of water.

This ceased abruptly, bringing forth an exultant cry from Harry, while
the other boys crowded around, speculating on the cause.

"I've got it!" cried Harry, dancing about the compartment. "I know what
he's going to do. Go to the porthole, Jimmie, and see where our friend is
now. Tell me just what he's doing. I'm going to stand guard over this
valve here for a while in case something happens."

"He's going back into his little cage!" stated Jimmie from his position.
"He's just shutting the outer door."

"Stand by to see something happen now, boys!" announced Harry.

"What's going to happen, Harry?" asked Jack.

Before Harry could answer, a sputter of water and air was observed at the
open valve. A small quantity of water was blown out of the pipe.
Following this came a rush of sweet, pure air that was ve