mbs, and the spot to be aimed at was
selected. This was a point in the water just inside of the mouth of
the harbour, and nearly a mile from the land on either side. The
distance of this point from the vessel being calculated, the cannon was
adjusted at the angle called for by the scale of distances and levels,
and the instrument indicating rise, fall, and direction was then put in
connection with it.

Now the Director-in-chief stepped forward to the button, by pressing
which the power of the motor was developed. The chief of the
scientific corps then showed him the exact point upon the scale which
would be indicated when the gun was in its proper position, and the
piece was then moved upon its bearings so as to approximate as nearly
as possible this direction.

The bow of the vessel now rose upon the swell of the sea, and the
instant that the index upon the scale reached the desired point, the
Director-in-chief touched the button.

There was no report, no smoke, no visible sign that the motor had left
the cannon; but at that instant there appeared, to those who were on
the lookout, from a fort about a mile away, a vast aperture in the
waters of the bay, which was variously described as from one hundred
yards to five hundred yards in diameter. At that same instant, in the
neighbouring headlands and islands far up the shores of the bay, and in
every street and building of the city, there was felt a sharp shock, as
if the underlying rocks had been struck by a gigantic trip-hammer.

At the same instant the sky above the spot where the motor had
descended was darkened by a wide-spreading cloud. This was formed of
that portion of the water of the bay which had been instantaneously
raised to the height of about a thousand feet. The sudden appearance
of this cloud was even more terrible than the yawning chasm in the
waters of the bay or the startling shock; but it did not remain long in
view. It had no sooner reached its highest elevation than it began to
descend. There was a strong sea-breeze blowing, and in its descent
this vast mass of water was impelled toward the land.

It came down, not as rain, but as the waters of a vast cataract, as
though a mountain lake, by an earthquake shock, had been precipitated
in a body upon a valley. Only one edge of it reached the land, and
here the seething flood tore away earth, trees, and rocks, leaving
behind it great chasms and gullies as it descended to the sea.

The ba