The morning news. [volume] (Savannah, Ga.) 1887-1900, 1898-04-21

the telescope on an object of known
range and turning the micrometer screw
until the horizontal wire cuts the water
line of the object. A tide gauge, showing
the hight of the tide for every hour, is
posted near the instrument, and at inter
walls of an hour or less the observer ad-
Jdsts the altitude scale, keeping the
length of the instruments vertical base
constant.
To get the range and azmuth of ap ob-
ject the operator looks through the tele-
scope, and by means of the two cranks
brings the intersection of the vertical and
horizontal wires on the point of the wa
ter line of the object to be aimed at. Upon
the range wheel he reads the range in
yards, and upon the azimuth scales the
azimuth in degrees and minutes. If the
target is moving he keeps the intersection
of the wires on it by turning the cranks,
the azimuth with his left hand and the ele
waiting with his right, without taking his
eye from the telescope. When the position
finder station is not in the battery the
range and azimuth for the guns are found
by a second operator who works a replot
ter arm carried by the traVersing arm.
The arm is adjusted when the instrument
is set up so that it gives the corrected All
nuth for the guns. At regular intervals
the observer calls out the ranges. The
assistant slides a pointer along a scale
arm to the range called and brings the
replotter arm in contact with the pointer
which at once shows the corresponding
range for the guns. Tests at Fort Wads-
worth show that it Is impossible to replot
the position of a moving target with re-
spect TO a gun at intervals of ten seconds
without hurry or confusion.
When a single battery is watching
warship the battery commander takes his
place at the position finder station, unless
the station is away from the battery, in
whichhcase the corrected ranges and All
muths are sent to him at ten, twenty or
thirty second intervals by telephone or tel
egraph. When the ship is first sighted
her range and azimuth are marked on
plotting chart of the harbor by another Of
ficer. An electric clock strikes the inter-
walls. AT each sound of the gong the OBJ
server calls out the range and azimuth of
the approaching ship, and the chart Off
Ger marks down the successive positions.
When three observations have been taken
the chart officer plots the course of the
ship. The chart shows the location of
the channels, and the plotting of the pro-
bable course of the ship is a simple mat
ter The officer marks a provisional
course, to be sustained or corrected by
subsequent readings from the instrument,
and the observation of the effects of the
n1e. AT Intervals dlOllS IlS CONl Sc WAtAiAt
the range of the guns of the battery, he
marks points, quickly calculating their po-
sitions and the times when the ship will
reach them.
The battery commander, who at the first
sight of the ship, went to the speaking
tubes and gave the officers in command of
the gun detachments the command
"Loadv' now calls up each detachment Of
ficer in turn and gives him the range and
azimuth of one of the predicted positions
plotted on the chart. Each gun officer
swings his gun around to the azimuth an
nounced, by turning a wheel until a point
err on the guns azimuth dial reads the cor
rect degrees and minutes; glances at his
range table, which shows the necessary
angle of elevation for the range, and raises
or lowers the gun by turing another wheel
until a pointer on a graduated arc reads
the angle. He gives the necessary COM
mands excepting the Fire"
Stopwatch in hand, his mouth at the
speaking tube to the first gun, the bat
terry commander waits until as many sec
onds before the predicted time of the $r
rival of the ship at the predicted point as
the proiectile will be in the air, and then
commands through the speaking tube,
'Firer' An officer in the position-inding
station. observes the effect of the fire. If
the ship is not struck, because of some
characterization, the necessary correction IS
made on the chart Each gun is fired at
the proper second of time and reloaded.
The chart officer, meanwhile, has made a
more accurate plotting of the ships
course from the ten-second observations,
and has a new point for each gun to be
aimed at. The new positions are sent 10 the
guns. and the firing continues at regular
intervals, a new range and azimuth be-
inc sent 10 each gun after 1t fires. Before
the ship can open fire on the battery she
,s bored through and through with the
hfeh-explosive shells and probably sunk.
one ship is powerless against battery OF
canal armament. BY means of the tele-
scopc sights on the guns, the detachment
officers may sight the guns on ships lying
NJ anchor or coming directly toward the
battery, the battery commanders calling
,,,t tho ranges only.