Butler citizen. [volume] (Butler, Pa.) 1877-1922, 1893-11-17
The Mighty Searcher Now in Use
ut Chicago.
The Reelected Beam Cast by the Nam
moth Lantern Equal to Millions
Upon Millions o;
Candles.

To America belongs the honor of con-
structing the largest and most power
full electric search light in the world,
now being set up at the worlds fair
1t stands about ten feet six inches high
to the upper side of the ventilator on
she top of the drum, and the total
weight is about 6,000 pounds, but SO
perfectly is it mounted and balanced
that child can move it in any di
rection.
The rejecting lens mirror used in
tins protector is $50 centimcters, or 60
inches in diameter. 1t is a concave
spherical mirror of the Mangin type,
free from spherical alteration, reflect
ing a sensibly parallel beam of light
1t was manufactured especially for this
protector in Paris, France, and is a
most perfect specimen of optical work,
three and one-fourth inches thick at
the edges and one-sixteenth of an inch
thick at the center, and weighs about
500 pounds.
The metal ring in which it is mount
ed weighs about $50 pounds, and the
total lens, ring and cover weigh about
600 pounds. This great mirror is
mounted at one end of the big drum,
the outer end of which is furnished
with door consisting of n metal rim
in which are fixed number of plate
glass strips five-sixteenths of an inch
thick by six inches wide. Inside this
drum and sliding upon ways arranged
on the bottom is placed the electric
lamp, the source of the light which is
reflected by the mirror.
1t is entirely automatic in its action,
is six feet high and weighs about 400
pounds. The carbons used are also
made especially for it. The upper or
positive carbon is one and one-haf
inches in diameter and twenty-five
and one-half inches long, with FIVE
sixteenth of an inch core of soft carbon
running from end to end through its
center The lower or negative carbon
is one and one-fourth inches in diane
ter. is fifteen inches long and also has
a core of soft carbon running through
its center. In addition its outer sur
face is heavily coated with copper.
The positive carbon is set n little in
front Of the negative, and thus almost
all the intense light of the incandes-
cent crater is east upon the reflector.
The maximum current at which this
lamp operates is 200 amperes. and at
this current the lamp has luminous
intensity of about 90,0 900 to 10000 can
dies, the reflected beam total lumin-
GUS intensity of about 375, ,o00, 900 can
dies. an intensity which the eye cannot
appreciate In looking at the side of
the beam the spectator only .distin-
guishes n stream of light of conpara-
lively low intensity, but in looking mt
the beam directly its brilliancy is full
ly seen and the effect Is absolutely
binding Ventilators at the top and
sides allow constant current of air
to pass through the drums and dissi-
pate the heat generated by the arc
lamp. and they are SO arranged that
no light can escape through them.
All the connections for adjusting the
positions of the cartons and the lamp
are brought through the drum to the
outside, and are arranged in close
proximity to one another at one side,
so that all may be manipulated by the
operator without moving from his po-
sition.. Through openings in the drum
covered by densely colored glass the
opposition of the lamp may be watched
and it's adjustments verified.
II was observed that the space with
in the beam was violently agitated,
and closer observation revealed the
fact that millions of moths and minute
insects were lowering in it, attracted
by the brillancy Of the light. Next
morning bushels of dead moths, beetles,
other insects and some small birds
were swept up from the roof on
which the protector stood. They had
been killed by the intensity of the
light.
How far the powerful beam OF light
of this instrument can be seen is diff
ficult to state. The search light set up
on Mount Washington, in the White
mountains. has n diameter OF only
thirty inches, and reflected light
from the mirror of about 100000 candle
power, yet the newspaper can be read
in it's beam ten miles away, and the
light can be seen from points 100 miles
away How much farther then could this
375, 900, 900 candle power light be seen
in clear atmosphere, free from
moisture, If the protector could be
mounted upon an eminence sufficiently
high to clear all obstacles.