Evening journal., 1898-08-12
SHARP SMOOTHING AT SEA

GtltAftI G4lJOilNG AT SEA
The accuracy OF modern riaed guns /
is cne Of the wonders Of engineering
Two experimental shots fred FEW
years ago at the same elevation from
tho same gun fell within thirty yards
II each other, after traversing a dis
lance OF Twelve miles. II modern
rifle is laid upon the target. with
proper elevation and allowance for
wlndase, IL Is safe to say the shot Will
iipd the mark. The correct elevation
Of the gun can only De determined N
tho distance OF the target is known,
and the cxact determination OF the dis
tance OF a moving object is a problem
that has worried the gunner ever since
the day whSn round shcc was first
thrown from the sides on the wooden
agLting ship.
In the early days The determination OF
he range was a ma,ter Of guesswork.
The gunner assumed a distance. ele-
waited h!s gun accordingly and watch
ed the course OF the shot. II It fell
short he increased the elevation. ana
II it passed over he decreased It. This
was all very well in a day when the
guns were too feeble to do much exc
cutlon, except at cloee range. and o
few dozen shots thrown away made at-
tie impression upon a ships magazines.
With the advent OF modern ordnance,
h-wcver, with its Cotton gums and cost
ly charges, the necessity OF accurate
fire becomes imperative, and ordnance
experts set about devising some sclen-
tltic method OF finding the range at
sea. The earliest and best known de-
vice of the kind was the invention OF
Lieutenant Fiske, of the United States
Navy, which has been installed on
many OF our ships. and "a widely IN
use in the various nayies OF the world.
The Fiske range finder Is based upon
The wsl known principles OF land sur
! veylrg with the transit and engineers
shain. II a surveying party come to a
, NCld liver whose width has to be
determined. base line i5 measured
Tong the bank, and the angles which
his line makes with a mark on the
pposite bank are measured by the
Z transit. Then, knowing the length Of
the base line and the two angles. tn,
distance across the river can be deter
mined by trlgonometry.
Applying this TO the range hnien
base line is carefully measured be
, tween two points near opposite ends
OF the ship, and over each point a
range finder, answering to the engi.
t, neer's transit, is permanently set up
II the telescopes OF the two finders ar,
simultaneously converged upon th'
same point on a distant object (ship
fortress or city), the observers will bi
IN possession Of the trigonometrica
data necessary to compute the distance
p nancy. the base and the two bas
angles.
In the din, hurry and slaughter Of
sea fight, however. it would be diff
4, cult to make the necessary calculations
as the distance between the ships, and
therefore. the observed angles keel
4 changing and in order to make th'
determinatiin Of the distance auto
/, matte, Lieutenant FIske placed hi
telescope IN the circuit Of Wheat
stone bridge and caused their chang
OF position to record the distance o
+, the object on the graduated scale OF I
i, delicate gaiyanometer All that wa
/. now necessary wGs for the observer
i at the two range finders TO keep tn
!. cross-hairs Of the telescope upon tn
+, same point Of the ship. and the elec
tric current translated las it were) tn
d, angles into distances and recorde
% them by the movement Of a need.
n over an arc graduated into hundred
y Of thousands OF yards One OF thes
galvanometers is placed in the connin
tower and one at each Of the princlpa
gun Scientific american.