The Dawson news. (Dawson, Ga.) 1889-current, 1898-08-03
l GREAT SEARCHLIGHT.
. rs At SAN FRANCISCO BAY, AND
uIUNINES THE OCEAN.
:, ..t Powerful Ever Constructed. Reveals
Movipg Objects Almost as Far as
Marine Glasses Can Carry


Marine Glasses Can Carry.
rbo limited States government has re-
,,,ly secured the most powerful cleo
.,ic searchlight in the world, and has
aIoced it at the entrance to San Fran
|sisco bay, to be USED in the protection
: onr western outpost in case of posi-
Ia attack The wisdom of this action
u tbe part of the government will be
conceded in view of the possibility of
International complications resulting
from the war.
Tbelight from this great protector is
calculated to be equal to
kbat of not less that 375, 100000 candles.
Tbe distance from which it Gamble seen
/ considerably over 100 miles, and NOV
mo objects can be detected by its light
almost as far as marine glasses can
garry.
Some idea of the size of this search
ght may be gained by the comparison
Known in the illustration. 1t stands 10
lee. inches high to the top of the drum,
Ind the total weight is about 5000
bounds, but SO perfectly is it mounted
Ind balanced that a child can move it in
kny direction, 1t was built by the Cen
eaI Electric Co.,, Of Schenectady, New
|York.
The rejecting mirror used is a concave
spherical mirror, five feet in diameter,
DETECTING a parallel beam of light. 1t
SBas manufactured especially for this
protector, and is a specimen Of perfect
optical work. three and ope-quarter
inches thick at the edges and one-six-
j eentb Of an inch thick in the center. 1t
weighs about 500 pounds. The metal
ling in which it is mounted weighs
about $50 pounds, and the total tense,
ing and cover weigh about 600 pounds.
This great mrrr is mounted at one end
sOf tire big drum, the outer end of which
is furnished with a door consisting of a
humber OF plate glass strips. Inside the
drum and sliding upon ways arranged on
Fhe bottom is placed the electric arc
|amp, the source of the light which is
nected BY the mirror. 1t is entirely
Itomatic in its action, is feet high
weighs about 400 pounds. The car
Pon8 used are also made especially for it.
he upper or positive carbon is / inches
II diameter and 224 inches long. The
over or negative carbon is Il inches in
glIameter and Is inches long. The outer
surfaces OF the carbons are heavily coat
n with copper. The positive carbon is
r. d IUtle 10 front of the negative, and
mus almost all the intense light of the
2uVaadeSeent crater of the arc is cast
Rpon the reflector.
AT Tue maximum current at which
~ lamp operates it has luminous in
lty VI about 10000 to 100 eco can
sieS-Che rejected beam a total lumi-
VuS Intensity of about 375, 900 900 can
~ "u intensity which the eye cannot
pIe%ate In looking at the side of
O7"h The spectator only distinguish
stream OF light of comparatively low
''HSl'!' but in looking at the beam
GUY the effect is absolutely binding.
'u''lators at the top and sides allow a
-''anC current of air to pass through
uou and dissipate the heat gener.
. W the arc lamp, and they are so
'uSeo mat no light can escape
,VuSn them to confuse the operator.
'"0 connections for adjusting the po-
''OHS Oh the carb0ns and the lamn AK
SUI through the drum to the out
> "nU are arranged in close proximity
~ another at one side. so that all
Oo manipulated by the operator
1OuC moving from his position
IOuSn Openings in the drum covered
IonSeiy colored glass the operation of
|Is, ,aulp may be watched, and its adj
i1'n'S made. The drum is support.
I'm - -. bearings at the top of a Y-shaped
LIN 'eI Ia base plate, running on
II -. wheels, forming a turntable. rest
~ massive pedestal supnortino
whole structure. The drum fork
O'Se plate are rotated borizontanr
LILY bo 'uFntable either by hand or nv
% aanlSm' The drum may also be 81.
II, or depressed vertically.
me past two years this great ,iobt
4 +p over the waters of the Paoiec
80 cue top of Mt. Lowe. From tho
H. =, tne mountain the great Whit
Ori,U ~ nght has shot forth into the Oh.