“Whenever the ‘Hudson’ shows up along this coast, and the officer in command of her gives the word.  That may be any hour, now.”

“Then we’d better find Eph,” suggested Captain Jack, “and pass him the word.  Won’t Eph Somers dance a jig for delight, though!”

“Yes; we’d better look both boats over at once,” replied Mr Farnum, picking up his hat “And we’ll leave word for Grant Andrews and some of his machinists to inspect both craft with us.  There may be a few things that will need to be done.”

As they left the office, crossing the yard, Captain Jack Benson and Hal Hastings felt exactly as though they were walking on air.  Even Hal, quiet as he was, had caught the joy-infection of these orders to proceed to Annapolis.  To be sent to the United States Naval Academy on a tour of instruction is what officers of the Navy often call “the prize detail.”

Farnum and his two youthful companions went, first of all, to the long, shed-like building in which the third submarine craft to be turned out at this yard was now being built.  From inside came the noisy clang of hammers against metal.  The shipbuilder stepped inside alone, but soon came out, nodding.  The three now continued on their way down to the little harbor.  All of a sudden the three stopped short, almost with a jerk, in the same second, as though pulled by a string.

At exactly the same instant Jacob Farnum, Captain Jack Benson and Engineer Hal Hastings put up their hands to rub their eyes.

Their senses had told them truly, however.  While the “Pollard” rode serenely at her moorings, the “Farnum,” the second boat to be launched, was nowhere to be seen!

“What on earth has happened to the other submarine?” gasped the shipbuilder, as soon as he could somewhat control his voice.

What, indeed?

There was not a sign of her.  At least, she had not sunk at her moorings, for the buoys floated in their respective places, with no manner of tackle attached to them.

“A submarine boat can’t slip its own cables and vanish without human hands!” gasped the staggered Jack Benson.

“There’s something uncanny about this,” muttered Hal Hastings.

Jacob Farnum stood rooted to the spot, opening and closing his hands in a way that testified plainly to the extent of his bewilderment.

CHAPTER II

HOW EPH FLIRTED WITH SCIENCE

Jack Benson was the first of the trio to move.

Without a word he broke into a run, heading for the narrow little shingle of beach.

“Got an idea, Captain?” shouted Jacob Farnum, darting after his young submarine skipper.

“Yes, sir!” floated back over Jack’s shoulder.

“Then what’s at the bottom—­”

“Eph and the boat, both together, or I miss my guess,” Captain Jack shouted back as he halted at the water’s edge, where a rowboat lay hauled up on the shore.