recognized the man who had been up
the tree. "It's that spy, Simpson, Tom!"

Chapter XII

Bridging a Gap

Such surprise showed both on the face of Ned Newton and that of the man
who called himself Walter Simpson that it would be hard to say which
was in the greater degree. For a moment the newcomer stood as if he had
received all electric shock, and was incapable of motion. Then, as the
echoes of Ned's voice died away and the young bank clerk, being the
first to recover from the shock, made a motion toward the unwelcome and
uninvited intruder, Simpson exclaimed.

"I will not bother now. Some other time will do as well."

Then, with a haste that could be called nothing less than precipitate,
he made a turn and fairly shot out of the door by which he had entered
the tank.

"There he goes!" cried Mr. Damon. "Bless my speedometer, but there he
goes!"

"I'll stop him!" cried Ned. "We've got to find out more about him! I'll
get him, Tom!"

Tom Swift was not one to let a friend rush alone into what might be
danger. He realized immediately what his chum meant when he called out
the identity of the intruder, and, wishing to clear up some of the
mystery of which he became aware when Schwen was arrested and the paper
showing a correspondence with this Simpson were found, Tom darted out
to try to assist in the capture.

"He went this way!" cried Ned, who was visible in the glare of the
searchlight that still played its powerful beams over the stern of the
tank, if such an ungainly machine can be said to have a bow and stern.
"Over this way!"

"I'm with you!" cried Tom. "See if you can pick up that man who just
ran out of here!" he cried to the operator of the searchlight in the
elevated observation section of what corresponded to the conning tower
of a submarine. This was a sort of lookout box on top of the tank,
containing, among other machines, the searchlight. "Pick him up!" cried
Tom.

The operator flashed the intense white beam, like a finger of light,
around in eccentric circles, but though this brought into vivid relief
the configuration of the field and road near which the tank was
stalled, it showed no running fugitive. Tom and Ned were
observed--shadows of black in the glare--by Mary and her friends in the
tank, but there was no one else.

"Come on!" cried Ned. "We can find him, Tom!"

But this was easier said than done. Even though they were aided by the
bright light, they caught no glimpse of