In the first period of the siege of a stronghold it is of very great
importance for the besieged to embarrass the first progress of the
attack, in order to complete their own armament, and to perform
certain operations which are of absolute necessity for the safety of
the place, but which are only then possible. In order to retard the
completion of the first parallel, and the opening of the fire, it is
necessary to try to discover the location of such parallel, as well as
that of the artillery, and to ply them with projectiles. But, on their
side, the besiegers will do all in their power to hide their works,
and those that they are unable to begin behind natural coverts they
will execute at night. It will be seen from this how important it is
for the besieged to possess at this stage of events an effective means
of lighting up the external country. Later on, such means will be of
utility to them in the night-firing of long-range rifled guns, as well
as for preventing surprises, and also for illuminating the breach and
the ditches at the time of an assault, and the entire field of battle
at the time of a sortie.
[Illustration: ELECTRIC LIGHT APPARATUS FOR ARMY USE.]
On a campaign it will prove none the less useful to be provided with
movable apparatus that follow the army. A few years ago. Lieut. A.
Cuvelier, in a very remarkable article in the _Revue Militaire Belge_,
pointed out the large number of night operations of the war of 1877,
and predicted the frequent use of such apparatus in future wars.
The accompanying engraving represents a very fine electric light
apparatus, especially designed for military use in mountainous
countries. It consists of a two-wheeled carriage, drawn by one horse
and carrying all the apparatus necessary for illuminating the works
of the enemy. The machine consists of the following parts: (1) A field
boiler. (2) A Gramme electric machine, type M, actuated directly by
a Brotherhood 3-cylinder motor. (3) A Mangin projector, 12 inches in
diameter, suspended for carriage from a movable support. This latter,
when the place is reached where the apparatus is to operate, may be
removed from the carriage and placed on the ground at a distance of
about a hundred yards from the machine, and be connected therewith by
a conductor. Col. Mangin's projector consists of a glass mirror with
double curvature, silvered upon its convex face. It possesses so
remarkable optical properties that it has been adopted by nearly
all powers. The fascicle of light that it emits has a perfect
concentration. In front of the projector there are two doors. The
first of these, which is plane and simple, is used when it is desired
to give the fascicle all the concentration possible; the other, which
consists of cylindrical lenses, spreads the fascicle horizontally, so
as to make it cover a wider space.
The range of the concentrated fascicle is about 86,000 feet. The
projector may be pointed in all directions, so as to bring it to bear
in succession upon all the points that it is desired to illuminate.
The 12-inch projector is the smallest size made for this purpose.
The constructors, Messrs. Sautter, Lemonnier & Co., are making more
powerful ones, up to 36 inches in diameter, with a corresponding
increase in the size of the electric machines, motors, and boilers.
The various powers make use of these apparatus for the defense of
fortresses and coasts, for campaign service, etc.
The various parts of the apparatus can be easily taken apart and
loaded upon the backs of mules. The only really heavy piece is the
boiler, which weighs about 990 pounds.
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