"Did you recognize him?" whispered Hal, quivering.

"No; too dark for that, and, besides, he was too quick. But we must
hustle to alarm someone."

"There's a watchman in the yard," Hal replied. "He ought to be getting
busy."

"I don't hear any hail, or any shot," Jack replied. "Hal, old fellow,
we've got to do something ourselves."

"Well, we can climb the fence as well as that stranger did."

"We'd better. Here, take the flashlight gun. Pass that and the camera
up as soon as I get to the top of the fence. We can't leave our outfit
outside--it's worth too much money."

With that Jack Benson swiftly found a knothole in which he could get
a slight foot-hold. With that start he was quickly up on top of the
ten-foot fence. Bending down he took camera and flashlight "gun."
Hal hurriedly followed. Down in the yard, they started speedily
though softly forward, going by impulse straight toward the submarine's
shed, though keeping in the shadow of other buildings.

Arrived at one corner of the office building, young Benson, who was
in the lead, signaled a stop. Hal halted just behind him.

"It's the submarine, all right, that the fellow's after," whispered
Jack excitedly, as he peeped. "Make him out over there, at the door?
Gracious! He's unlocking and throwing the padlock off. And, blazes!