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 un.o.bserved signal to someone on sh.o.r.e. "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 sh.o.r.e 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. Farnum again conducted his guests back to the state-room. When Captain Jack summoned them forth, they returned to find Hal Hastings, laughing in a way that showed his white teeth, standing there in his dripping garments.

"From what you have seen, gentlemen," said the builder, seriously, "I am sure you will understand that we have mastered a new feature, of great value in submarine boating." The three Navy officers struggled to conceal their wonder.

"Make for the surface, Captain Benson," directed the owner.

When the pa.s.sengers aboard the submarine stood once more on the platform deck, the yard's owner signaled for the sh.o.r.e boat to lay alongside.

Into this small boat he took his guests. The boat was rowed away two or three lengths, immediately after which the "Pollard" again sank.

Two or three minutes pa.s.sed. Then Captain Jack's head shot above the surface. He made for the boat, hanging onto the gunwale.

"It would be bad judgment to call you young fellows mermaids," said Commander Ennerling, dryly, "but you are surely _merboys_."

A moment later Hal Hastings's head came above the surface.

"Mr. Pollard and young Somers could as easily leave the boat and join us," explained Mr. Farnum. "However, if the last man aboard leaves the boat then there is no way provided for a return to the 'Pollard,'

and we would be placed at great expense in raising her. I think we have, however, shown you enough to make you believe that we have mastered some new wrinkles in submarine work."

"You have shown us more than we can quite digest," admitted Lieutenant Commander Briscoe. "But how is this all done?"

"That," responded Mr. Farnum, gravely, "the Government will know when the boat is purchased for the American Navy."

The anchor being again lowered, both Jack and Hal dived below. In five minutes the "Pollard" was on the surface. Mr. Farnum asked:

"Have we shown you enough at one time?"

"Yes," admitted the officers. "This evening, after dark, we may ask you to take us out and show us your boat's diving powers."

"Jack, my boy," whispered Jacob Farnum, when the young captain joined the party on sh.o.r.e, "your trick of leaving and returning to the boat when it lies on the bottom has gotten our friends of the Navy into a state of hard guessing. Do you think we'd better show them some more of it at another time?"

"If you want my opinion, sir, I think we'd better not. We've puzzled them this time, but if we keep on doing the trick for them, I'm afraid they'll soon guess how it's done. I don't believe, sir, you can fool the American Navy more than once."

CHAPTER XV

SERVING IN THE CAUSE OF PEACE, NOT WAR

"It seems almost a shame to have to go below," sighed Lieutenant McCrea.

It was evening, the time about nine o'clock. For nearly an hour the "Pollard" had been running out to sea at something below her full speed.

She was now something like a dozen miles off the coast.

Commander Ennerling had just decided that it would be a good time to test the diving capabilities of the submarine.

Ventilators were shipped, and all other preparations had been made for going below the surface.

Eph was left in the conning tower, Lieutenant McCrea with him.

"How far do you want the dive to be made, sir?" asked Jack Benson.

"A depth of forty feet ought to serve the purpose," stated the president of the board.

"Then, sir, we will make a sloping dive to that depth, then complete the curve until we strike the surface again," proposed the submarine boy.

"How will that suit you, sir?"