The midland journal. (Rising Sun, Md.) 1885-1947, 1898-04-22
AIMING BIG GUNS.
HOW MONSTER CANNON ON BAT
TLESHlPS ARE HANDLED.

BY the Use of DeIicately- Adjusted Range
Finder the Utmost Accuracy is Obtained
-Usod on seacoast Defences as Well
as on Ships.
In reply to an inquiry from James
Thompson, of Chicago, 1 would say,
writes W. E. Curtis, that the range
finder used on our seacoast defences
is not a Government secret, but is
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 were
invented by Captain Watkins, an
English engineer; Lieutenant Lewis,
of our Army, and Lieutenant Fisk, of
our Navy. They are very complicat-
ed, and it is difficult to explain their
operation so it can be understood by
laymen. All such inventions are an
appliance of the mathematical princi-
pie that, knowing the base of tri-
angle and the two angles at it's ex-
tremities, one can calculate the dis
| tance between them. On coast de-
fences the base of the triangle is per-
manent, with fixed objects to mark it's
terminus. 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-
nt hi in1, +lo -
catch the distance of his target at
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, a rapid mathematical calcula-
tion is made, the book of tables is re-
ferred to, and in a moment the gunner
may know whether the enemy's cruis-
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 it is said to be
absolutely accurate, and the apparatus
| is so sensitive and regulated to such
fine degree that by turning a key
monster gun weighing a hundred tons
can be instantly adjusted so that with
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 a material
factor in his problem. He must also
make allowances for the wind, for the
resistance of the atmosphere, for the
curvature of the earth and for the
movement of the enemy's fleet if it is
in motion. The range-fnder is, how
ever, great deal more accurate than
the human eye, and persons with de-
fective vision will often insist that
gun is badly aimed aud find out to the
contrary after the shot is fired
| Although we have guns on our bat
tle-ships and in the fortresses on the
coast that will carry a projectile thir-
teen miles it would be folly to attempt
| w uSo 'hoaA a. liirs aistaACs, uecduSe,
owing to the curvature of the earth, it
would be impossible to see the target.
A man in a small boat upon the sur
face of the water cannot see more
than four miles. From the bridge of
an ordinary man-of-war, which may
be thirty feet from the water, a 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 indistinct9y, and that is the
limit of human vision on a level sur
face.