The San Francisco call., 1903-09-20

IN Of light Of the almost inconceiv-
able intensity Of 3l6,O00, 900 candle
n power is one OF the latest me-
misunderstanding achievements
It is the work Of Schuckert & Co, Nu-
remberg, Germany. 1t has diameter OF
SIX feet six inches and is fitted with ar
iris shutter, hslf-closed, as shown in the
accompanying picture.
This searchlight is electrically con-
troled by two levers, one Of which gov
erns the motor mounted in the base Of
the apparatus which operates the pro-
-ector If a vertical direction through
train OF gear wheels, while the other
starts or stops the electric motor which
controls the horizontal movement Of the
beam OF light.
The iris shutter is used in order to make
the protector perfectly Nght-tight at any
moment desired, and it operates similarly
10 this type Of shutter as applied 10 mod
ern cameras. The leaves Of the iris dia-
phragm slide within fixed diaphragm To-
Gated in the axis Of the ray OF light and
provided with fold On some of the
German searchlights an apparatus known
as a double dispenser" is provided in or
der 10 convert concentrated light rapidly
into dinused light. This arrangement
consists OF two parallel systems of cylin-
GLlCaA lenses WnlEn may De SIG against
one another, whereby the angle of disper-
sion Of the emitted ray can be varied at
will. BY means Of this apparatus the
angle OF dispersion OF the light can be
varied within limits of from two degrees
TO 1Orty-five degrees if desired.
A new form OF electric fiashlight has
lately been installed by the same concern
in the lighthouse tower at Heligoland.
The searchlights or projectors used in
r1~sa
in the accompanying views taken from
the Scientific American.
There are three lower searchlights. ar
ranged 10 degrees apart and another
mounted upon the top, all operated auto
matically and driven by electric motors.
The carbons which are fed by automatic
mechanism, arc placed in a horizontal po-
sition, as is usual with most large search
lights. The intensity Of the light is q. 1000.
900 candle-power as a minimum, and the
maximum current used IS 100 amperes
The light flashes occur every five seconds
and they remain in one position anly one
tenth Of a second.
The three searchlights mounted on the
lower revolving platform I20 degrees apart
have mirrors twenty-nine inches in diam
et9r and utilize direct current of thirty
four amperes each. the platform revolv-
ing at the rate Of four revolutions Der
minute. The current is supplied to the
tower lights by a lead iron-armored GOV
cred cable connected with the power sta
ton The power plant consists of two
steam engines directly connected to dy-
namos of 2l6 amperes capacity at a pres.
sure Of seventy-five volts
This new electric beacon is to take the
place Of the old petroleum light that SC
long flashed out its danger signals at the
mouth Of the River Elbe. The new elec.
tric light is probably the most powerful
at present IN operation. Apart from IFS
enormous power the Heligoland light
return has been made TO the old form ol
parabolic mirror, with a powerful light
In the focus instead OF the usual Fresno
lenses and prisms.
The mirrors of the Heligoland ligh-
consist each Of a piece of silvered glass
No protection against weather is provided
in front Of the light and II is asserted
that none is needed. Besides the three
mirrors mentioned, a fourth mirror ant
lamp is provided. which will turn thre,
times as rapidly, but which. il is said
viii be used only in cases of emergency
The duration of one-tenth OF a second
for the fash, a characteristic of mos
French beacon lights. is here adopted fol
The first time in Germany. II IS, how
ever a question whether these brief dur
atoms have not been carried to an ex
treme- Undoubtedly one-tenth of a sec
md Is sufficient to make the maximum
Impression on the eye when the light Il
brilliant But with a hazy atmospheri
nd the light much diminished ii is doubt
hi whether longer duration should no