“Hold fast!” he roared down the stairway.

Then he did the only thing that could be done in a second.

Without waiting to shut off the gasoline power, he reached out for the conning tower controls.  Like a flash, and with high nervous energy, he operated the mechanism that would fill the diving tanks in an instant.

In rushed the water, faster than it had ever done before.  Down dived the “Pollard” like a lump of lead.  To the startled onlookers on other ships she seemed almost to stand on her nose.  Those on the decks of the two nearest battleships saw the “Pollard’s” propellers uppermost of all, and revolving fast.

Then out of sight went the little submarine.  Those below in her cabin and engine room had been pitched forward on their faces.  Captain Jack fairly sprawled over the wheel.

Down went the little boat to a depth of some seventy feet.  Then Captain Jack had the presence of mind to bring her to an even keel.  A couple of hundred yards he ran under water.  Then, shutting off the motive power, he called below to turn the compressed air slowly into the water compartments.

“For I want to rise mighty gently,” he called down, in explanation.  “Then, if we come up under some craft’s keel, we won’t hurt them or ourselves.”

By this time the deck rails and rigging of many a naval vessel were crowded with officers and men, all anxious to know the fate of the plucky, or foolhardy, crew of the submarine.

A few moments passed.  Then the conning tower emerged from the water.  Next, the boat appeared, and rode at her proper amount of freeboard over the water.

What a deafening din of cheers filled the air.  Men, everywhere, were waving uniform caps.  Four of the big ships blew their whistles in harsh salute to this latest dash of Yankee bravery.

“Let us up on deck,” cried David Pollard, excitedly.  “We want to acknowledge some of that applause as modestly as possible.”

The submarine’s entire crew were speedily on the platform deck, while Captain Jack was busily explaining to his friends the necessity that had arisen for such a prompt, deep dive.

“Oh, but that was magnificently done, Jack!” cried the inventor, in a transport of enthusiasm.  “Hear them yell!  See them wave!  The din of the whistles!  It was the best thing we’ve done or could do in the way of compelling advertising!”

“Advertising be—­will keep!” rasped Jacob Farnum.  “But, for now, Captain Benson, hustle over to that pier as fast as the speed of the boat will allow.  Advertising—­with Grace Desmond’s fortune and happiness at stake!”

So the young captain turned on speed, and steered on through the lanes of Naval vessels.  Even on those craft from which his dashing, daring performance had not been witnessed the news was known, now, passed from ship to ship by the wig-wagging of signal flags.

All the way into the pier the “Pollard” was greeted with tempestuous volleys of applause, for there is nothing the American naval tar loves as he does sheer, wild grit.