Butler citizen. [volume] (Butler, Pa.) 1877-1922, 1898-06-16
AIMING BIG GUNS.
HOW MONSTER CANNON ON BAT
TLEsHips AaE HANDLED.
Gy sI.o Uso of o DelicateIy-Adjusted Range
Finder the Utmost Accuracy Is Obtained
-Ssvd on Ssacosst Defences ss Well
Ships.

fsy shs Usc of o Delicately-AdjUsted Range
Finder the Utmost Accuracy Is Obtained
-Ssvd on saacosst Defences se Well
on ships.
In reply 10 an inquiry from James
Thompson. Of Chicago. I would say,
writes ". Z. Curtis. that the range
finder used on our seacoast defences
is not q Government secret, but is a
patented appliance, an Improvement
upon system that has been in use
since ancient times. There are In use
three sets of apparatus somewhat DIFF
ferent from each other, which We're
invented by Captain Watkins, an
English engineer; Lieutenant Lewis,
OF our Army, and Lieutenant Fisk. of
or Navy They are very compiicat-
ed and II Is difficult to explain their
operation so il can be understood by
laymen. All such Inventions are an
appliance Of the mathematical princi-
pie that, knowing the base OF q tTi-
angle and the two angles at its ex-
tremities one can calculate the dis
tance between them. On coast de-
fences the base Of the triangle Is per-
msnent, with fixed objects to mark its
terrlinus. The angles are ascertained
BY observations through Instruments
made for that purpose, and when they
are known there Is a series of printed
calculations covering all possible situ-
ations which enables the gunner to
catch the distance of his target at a
glance.
At sea, when vessel is moving,
the base is fixed and measured upon
the deck. a telescope is placed at
either end OF that line, and the lenses
of both are focused upon the object
TO be shot at. An observation is then
taken, rapid mathematical calcula-
ton is made. the book Of tables is re-
ferred to. and 81 a moment the gunner
| may know whether the ehemys cTuis-
er Is five and one-half or six and one
fourth miles away. or any other given
distance. This. Of course. requires a
great deal of technical skill and ma
thematical ability, but II Is said to be
absolutely accurate, and the apparatus
is so sensitive and regulated to such
fine degree that by turning u key &
monster gun weighing a hundred tons
can be instantly adjusted so that with
given quantity Of powder II VIII
carry a proiectile of 4 given weight
exactly the distance which the range
finder has determined. OF course, tho
gunner must know the contents OF hIs
cartridge, because that is material
factor in his problem. He muet also
make allowances for the wind for tne
| resistance Of the atmosphere. for the
curvature or the earth and Tor the
in motion. The TaDge-findef Is, how
ever. great deal more accurate shan
the human eye. and persons with de-
fecttve vision will often insist that a
gun is badly aimed and find out to the
contrary after the shot Is iTe1
Although we have guns or our bat
tle-ships and in the forsresses on ;he
coast that will carry pToject'le tEir-
teen miles 1t would be folly to attempt
to use them at that distance. because.
owing to the curvature Of the earth, il
would be Impossible to see the target
A man In small boat upon the stl-
face of the water cannot see mere
than four miles From the bridge Of
an ordinary man-of-war. which may
be thirty feet from the water, q man
with good eyesight or with glass can
see eight or nine miles. A man al the
masthead can see ten or twelve miles.
but very indistinctly and that is tho
limit of human vision on Il level sur
faro