New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1898-02-13
HOW BIG GUNS ARE AIMED.
THE RANGE FINDER USED ON sEACoAol
DEFENCES AND BATTLESHiPS.
W y curtis in The Chicago Record.

W r, Curtis in The Chicago ftecOfu'
In reply to an inquiry from James thompson Sa.
Of Chicago. | would say that inc Idh6e
used on our seacoast defences rs not a Ho'e'h-
ment secret but is a patented appliance an W..
provement upon "A system that mas peeh III VS.
since ancient times. There are IN use 'nice 80
~ annaratus somewhat different from each
other which were invented by captain Wat
kins an English engineer; Lieutenant Lewis, OF
our Army and Lieutenant FISK. OF our our Ny ~
They are very complicated, and II Is dIncui' ~
explain their operation so 1t can be unders'ooo
by laymen All such inventions are an app.,
ance of the mathematical principle that hho"
ing the base OF a triangle and the TWO angles ID
its extremities. one can calculate the distance
between them. On coast defences the base oi
the triangle is permanent. with nXeo opJects ~
mark it's terminus. The angles are ascertained
bv observations through Instruments MADE lor
that purpose and when they are known there is
a series of printed calculations covering al pos
sbe situations which enables the gunner I"
catch the distance OF his target AT glance
AT sea when a vessel is moving, the base Is
fixed and measured upon the deck. telescope
is placed at either end or thar line, ana 'he
lenses of both are focused upon the opJec. "
be shot at. An observation IS then taken,
rapid mathematical calculation - made the
book of tables is referred to, and in lnonefi
the gunner may know whether the enemy
cruiser is five and one-half or six and one-fourth
miles away. or any other given distance Inis,
of course. requires great deal or techhlcai Skill
and mathematical ability, but IL IS saiu 10 pe
absolutely accurate and the apparatus Is so
sensitive and regulated to such fine degree
that by turning key a monster gun weighing
a hundred tons can be instantly adjusted 30
that with a given quantity OF powder it will
carry a projectile OF a given weight exactly the
distance which the range-finder has determined
OF course. the gunner must know the contents
Of his cartridge. because that Is materia lac
tor in his problem. He must also make allow
ances for the wind. for the resistance or the at
mosphere, for the curvature OF the earth ana
for the movement OF the enemys fleet II II is IN
motion. The range-finder is, however, a great
deal more accurate than the human eye ano
persons with defective vision will often insist
that a gun is badly aimed and find out to the
contrary after the shot is fired
Although have guns on our battle-ships
and in the fortresses on the coast that will carry
a projectile thirteen miles ii would be folly TO
attempt to use them at that distance. because.
owing TO the curvature OF the earth, II would
be impossible to the target. man IN
small boat upon the surface Of the water cannot
see more than four miles. From the bridge or
an ordinary man of-war, which may be thirty
feet from the water. man with good eyesight
or with glass can see eight or nine miles A
man at the masthead can see ten or twelve
miles. but very indstnctly and that is the limit
OF human vision level surface.