ed Ned.
"They've got to the outside boat now. Now they're turning back."

"Better get that hatch closed so we can dive," admonished Jimmie. "This
is our time for getting out of sight in a hurry!"

"There goes their searchlight!" shouted Frank, who had crowded up the
ladder close beside Ned. "They're going to spot us in a hurry!"

"Ah," cried Ned as a sullen roar came to their ears. "They're taking a
chance shot at us from that cannon on the hill. Let's dive!"

Quickly the two boys adjusted the hatch. As they signaled to their
companions that this task was completed Harry and Jack turned the
deflecting rudders. The half-manned submarine slowly began to descend.

"Get some water into the tanks quick, Harry!" called Jimmie.

"Pump's going right now!" declared the other. "We're going down!"

"Take a look through the periscope, Ned," requested the pilot, "and let
me know what you can make out. Can you see any buoys ahead?"

"Try to see if they've located us with their searchlight," suggested
Mackinder. "Maybe they are getting our range with that gun!"

"Never mind about that searchlight," snapped Jimmie. "I want to find out
what's ahead, not what's behind us. We'll run this boat!"

"I simply wanted to know," objected Mackinder somewhat ruffled at the
lad's peremptory manner. "No objection, is there?"

"All the objection in the world!" declared Jimmie. "You're quite welcome
aboard as a passenger, but we'll navigate the vessel, please!"

Scarcely knowing whether to be amused or defiant at this attitude
Mackinder chose the wiser course and refrained from further comment.

Although the boys could not be sure that the persons on the island were
making efforts to hinder their escape they felt the better course was to
remain beneath the surface until well out of the harbor.

Directly Jimmie called the attention of his comrades to an object in the
water at no great distance ahead. The rays of the searchlight with which
the submarine was provided indistinctly revealed a huge bulk slightly
above the level at which they were traveling.

"What is that, a ship?" asked Harry wonderingly.

"I'll bet a cookie that's a mine!" declared Jimmie positively. "I'm going
to give it a little more leeway, anyhow. It pays to be safe!"

Ned was working the periscope in an effort to locate the buoys as
directed by Jimmie. Occasionally he turned the glass toward the group of
buildings they had just left.

"They're shooting at us, I gue