a specialty of ours in the harbor at Dunhaven."

"Very good," agreed the president of the board.

Not until they were in sight of the little harbor was the manhole opened.
Now, some of the party stepped out onto the platform deck and remained
there a few minutes.

"I'll have to ask you to come inside, now, gentlemen," requested Jack
Benson, courteously, after making an unobserved signal to someone on
shore. "We're going down to the bottom of the harbor."

As soon as the "Pollard" had sunk, and rested on bottom, Jacob Farnum
invited the members of the board into one of the staterooms aft.

"For just a few minutes, gentlemen," he explained, "we want to keep
you from seeing something."

As soon as the visitors were out of the way, Captain Jack sprang forward
to the torpedo tube. Hal Hastings, stripping off his outer clothing,
stood forth in his bathing suit.

"Into the tube with you, now," whispered Jack. "Crawl well
forward--right up to the forward end of the tube--so. Get hold of the
crossbar of the cap. Hold on hard. Now, when we close the rear port,
and open the forward cap, with a little rush of compressed air, the cap
will open forward and up, dragging you out into the water. Now, then,
got a good hold?"

"A grip like death itself," laughed Hal.

"Be ready, then."

Captain Jack closed the rear port of the tube, and turned on some
compressed air, which also drove the forward port open and up. A moment
later the submarine boy tapped at the door of the state-room.

"Has anything happened?" smiled Mr. Farnum.

"Hal Hastings is missing, sir," reported Jack.

"Missing?" demanded the boatbuilder, leading his guests out into the
cabin.

Young Benson pointed to the pile of clothing, just as Hal had left it on
the floor.

"Get to the surface," commanded Mr. Farnum. "We shall have to look into
this."

Soon the conning tower of the "Pollard" reappeared above the waves.

"Hal is safe, gentlemen," reported Captain Benson, from the tower.

An instant later he opened the manhole of the tower, allowing all hands
to step out on deck.

Grinning delightedly, Hal stood in the bow of the small shore boat.

"How did he get there, from a submarine on the bottom?" asked Commander
Ennerling, in astonishment.

"That is one of the secret features of this boat," laughed Mr. Farnum.
"Now, gentlemen, if you will kindly come below again, we're going to
sink."

Hardly had the submarine touched bottom before Mr.