of a mile ahead of the repeller, moved slowly; for
between them they bore an immense net, three or
four hundred feet long, and thirty feet deep, composed
of jointed steel rods. Along the upper edge of this
net was a series of air-floats, which were so graduated that they
were sunk by the weight of the net a few feet below the
surface of the water, from which position they held the
net suspended vertically.

This net, which was intended to protect the
repeller against the approach of submarine torpedoes,
which might be directed from the shore, was anchored at
each end, two very small buoys indicating its position.
The crabs then falling astern, Repeller No. 1 lay to,
with the sunken net between her and the shore, and
prepared to project the first instantaneous motor-bomb
ever used in warfare.

The great gun in the bow of the vessel was loaded
with one of the largest and most powerful motor-bombs,
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