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.