Richmond dispatch. [volume] (Richmond, Va.) 1884-1903, 1898-05-18
sHARP-sHOOTING At SEA.
Accuracy of Gun Firing Secured by
the Use OF the Range-Finder.

The Scientific American says: The accu-
racy of modern rihed guns is one of the
wonders of engineering. Two experiment
TAI shots fired a few years ago at the
same elevation from the same gun fell
within thirty yards Of each other. after
traversing distance of twelve miles. If
modern rifle is laid upon the target,
with proper elevation and allowance for
windage, IL is safe to say the shot will
md the mark. The correct elevation of
the gun can only be determined if the
distance Of the target is known and The
exact determination of the distance Of a
moving object is problem that has wor-
req the gunner ever since the day when
round shot was first thrown from the
sides Of the wooden fighting ship.
In the early days the determination of
the range was a matter of guesswork.
The gunner assumed a distance, elevated
his gun accordingly. and watched the
course of the shot. If it fell short he in
creased the elevation, and if it passed
over he decreased it,. This was all very
well in day when the guns were too
feeble to do much execution, except at
close range. and few dozen shots thrown
away made little impression upon a
ships magazines. With the advent of
ton guns and costly charges, the neces-
sity Of accurate fire became imperative.
and ordnance experts set about devising
some scientific method of finding the
range at sea- The earliest and best
known device of the kind was the inyen-
ton OF Lieutenant Fiske, Of the United
states navy, which has been installed on
many or our ships and is widely in use
in the various navies Of the world.
The Ffske range-finder is based upon
the well-known principles Of land sur
veying with the transit and engineers
chain. If a surveying party come TO a
broad river, whose width has to be de-
termined, a base line is measured along
the bank, and the angles which this line
makes with mark on the opposite bank
are measured by the transit. Then.
knowing the length OF the base line and
the two angles. the distance across the
river can be determined by trigonometry.
Applying this to the range-finder, a base
Line Is carefully measured between two
points near opposite ends of the ship. and
over each point a range-finder, answering
10 The engineers transit. is permanently
set up. Ii the telescopes OF the two find
ers are simultaneously converged upon
the same point on a distant object (ship.
fortress, or city, the observers will be in
possession OF the trigonometrical data
necessary to compute the distance-name-
ly. the base and the two base angles.
In the din, hurry, and slaughter of a
set tight, however, 1t would be dIncut
to make the necessary calculations. as
the distance between the ships. and there
fore, the observed angles, keep changing.
and in order TO make the determination
OF the distance automatic, Lieut.. Fiske
placed his telescope in the circuit OF a
Wheatstone bride and caused their
change of position TO record the distance
OF the object on the graduated scale of
delicate galvanometer. All that was
now necessary was for the observers at
the two range-iinders to keep the cross
hai:s or the telescope upon the same
point OF the ship 6rd the electric cur
rent translated. as II were, the angles
Into distances and recorded them by the
movement OF needle over an arc grad
uated into hundi eds and thousands OF
yards. One OF these galvanometers is
placed In tue coming tower and one at
each Of the Principal gun stations.