worked with electric
piles of recent invention which imparted enormous propulsive power to
the motor.

It goes without saying that no one imagined that Count d'Artigas was
none other than Ker Karraje, the former pirate of the Pacific, and
that Engineer Serko was the most formidable and resolute of his
accomplices. The former was regarded as a foreigner of noble birth and
great fortune, who for several months had been frequenting the ports
of the United States, the _Ebba_ having been launched long before the
tug was ready.

Work upon the latter occupied fully eighteen months, and when the boat
was finished it excited the admiration of all those interested in
these engines of submarine navigation. By its external form, its
interior arrangements, its air-supply system, the rapidity with which
it could be immersed, the facility with which it could be handled and
controlled, and its extraordinary speed, it was conceded to be far
superior to the _Goubet,_ the _Gymnote_, the _Zede_, and other similar
boats which had made great strides towards perfection.

After several extremely successful experiments a public test was given
in the open sea, four miles off Charleston, in presence of several
American and foreign warships, merchant vessels, and pleasure boats
invited for the occasion.

Of course the _Ebba_ was among them, with the Count d'Artigas,
Engineer Serko, and Captain Spade on board, and the old crew as well,
save half a dozen men who manned the submarine machine, which was
worked by a mechanical engineer named Gibson, a bold and very clever
Englishman.

The programme of this definite experiment comprised various evolutions
on the surface of the water, which were to be followed by an immersion
to last several hours, the boat being ordered not to rise again until
a certain buoy stationed many miles out at sea had been attained.

At the appointed time the lid was closed and the boat at first
manoeuvred on the surface. Her speed and the ease with which
she turned and twisted were loudly praised by all the technical
spectators.

Then at a signal given on board the _Ebba_ the tug sank slowly out
of sight, and several vessels started for the buoy where she was to
reappear.

Three hours went by, but there was no sign of the boat.

No one could suppose that in accordance with instructions received
from the Count d'Artigas and Engineer Serko this submarine machine,
which was destined to act as the invisible tug of the