Gilpin observer. (Central City, Colo.) 1897-1921, 1918-08-01
NAes Find Powerful and Far
Reaching Illumination an I'm
portant Factor.
USEFUL IN spoTT|NG TANKS
Pick Up Hun Bombing Planes at q
Distance and Keep Them Con.
stantIy In view-EquIpped
With Sound Detectors.

NeW AOTk.-IdSt 1dii, WHEN tHe AUS
TRANS were driving the Italian SOL
diers from their hard-won mountain
fortresses, the defeated army had one
weapon which 1t constantly used to
harass and impede the foe. This was
the electric searchlight, newcomer.
on the field of battle.
Powerful lights were trained every
night upon the advancing Austrians
whenever they came to river cross
ing or whenever they were obliged to
halt for another reason. This ham,
pered and irritated the enemy ex-
ceedingly. 1t was not only that Sc
rious danger attended any disclosure
Of their operations. They suffered
also from nerves when the long feel
and hands and revealed every detail
Of the work upon which they were
engaged.
The use of searchlights by our
own expeditionary forces is becoming
an important branch of the engineer
ing service. Not long ago congress
voted an appropriation of $1,0O0OOO
for searchlights of both the field type
and the anti-aircraft type. The lights
commonly used are 36-inch lights. hav-
ing candlepower of 1000 600, 900. and
a maximum range of approximately
10000 yards. or nearly six miles.
First Use In Warfare.
When searchlights were first intro
duced in warfare 1t was expected that
they would be primarily service
able in battlefield illumination. The
scheme was to throw light upon the
opposing battle line and show ad-
vancing companies Of infantry the
kind of ground over which they had
to go. Another plan vas to have
rows Of searchlights parallel with the
trenches and sweep the terrain be-
fore them, lighting up the barbed-
wire entanglements laid by the foe
and exposing parties Of enemy SOL
diers at work repairing them. How
ever, neither Of these uses turned out
to be especially significant. The DIFF
6culty was that, as soon as the lights
were in operation. they were easily
picked of by the enemy's guns. In
the same manner, they could not be
placed along the line of trenches
More recent experiments have dem
onstated that there is real useful
ness for field searchlights. They are
now being employed to spot the en-
emy's tank advances. Instead of be-
ing hauled by horses, like the first field
searchlights, the newer ones are
mounted on motor trucks They are
flashed for only minute or two at
time. and are instantly shifted to an
other vantage point. This affords
them a greater measure Of self-prO-
lection.
The antiaircraft searchlight is the
most valuable type Of light now used
by our soldiers. 1t is our most eff
fective defense against the low-fying
night-bombing plane of the Germans.
Antiaircraft guns have proved almost
hopelessly inadequate in coping with
night air raids, and If It were not for
the long pointing fingers Of the search
light the foe would be able to effect
some very deadly work in night at
tacks upon supply depots and ammuni-
ton dumps.
The method is to pick up hostile
bombing plane when 1t is about five
miles away from its objective. For
this purpose the searchlights are To-
Gated at points likely to be attacked.
They are sunk in holes in the ground
and are heavily sandbagged. Both the
light and the men working 1t are given
considerable protection.
Fitted With Sound Receivers.
To detect the approach Of airplanes
the searchlight apparatus is furnished
with sound receivers. Without these
receivers the outfit is practically use
less. The receiver can be swung
around to catch the sound vibrations,
and they are remarkably accurate In