e skilfully manoeuvred a free balloon by means of upper
currents, so as to convey all-important intelligence to besieged
Mafeking, and he proved that it would have sufficed if the balloon could
have been "tacked" across the sky to within some fifteen miles of the
desired goal.

The mode of signalling which he proposed was by means of a "collapsing
drum," an instrument of occasional use in the Navy. A modification
of this instrument, as employed by the writer, consisted of a light,
spherical, drum-shaped frame of large size, which, when covered with
dark material and hung in the clear below the car of a lofty balloon,
could be well seen either against blue sky or grey at a great distance.
The so-called drum could, by a very simple contrivance, readily worked
from the car, be made to collapse into a very inconspicuous object, and
thus be capable of displaying Morse Code signals. A long pause with the
drum extended--like the long wave of a signalling flag--would denote a
"dash," and a short pause a "dot," and these motions would be at once
intelligible to anyone acquainted with the now universal Morse Code
system.

Provided with an apparatus of the kind, the writer made an ascent from
Newbury at a time when the military camps were lying on Salisbury Plain
at a distance of nearly twenty miles to the south-west. The ground
wind up to 2,500 feet on starting was nearly due north, and would have
defeated the attempt; again, the air stream blowing above that height
was nearly due east, which again would have proved unsuitable. But it
was manifestly possible to utilise the two currents, and with good luck
to zig-zag one's course so as to come within easy signalling distance
of the various camps; and, as a matter of fact, we actually passed
immediately over Bulford Camp, with which we exchanged signals, while
two other camps lay close to right and left of us. Fortune favouring us,
we had actually hit our mark, though it would have been sufficient for
the experiment had our course lain within ten miles right or left.

Yet a further use for the balloon in warfare remains untried in this
country. Acting under the advice of experts in the Service, the writer,
in the early part of the present year, suggested to the Admiralty the
desirability of experimenting with balloons as a means of detecting
submarine engines of war. It is well known that reefs and shoals can
generally be seen from a cliff or mast head far more clearly than from