Daily press. [volume] (Newport News, Va.) 1896-current, 1898-04-07
AIMING BIG GUNS.
HOW MONSTER CANNON ON BAT
TLESHlPS ARE HANDLED.

BY the Use of Delscate1y- Adjusted Range
Finder the Utmost Accuracy is Obtained
-:.ed on SoRcoast Defences as well
as ON Ships.
In reply to an inquiry from James
Thompson, of Chicago, l would say,
writes w. E. Curtis, that the range
finder used on cur seacoast defences
is not Government secret, but is a
patented appliance, au 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 a tri-
angle and the two angles at it's ex-
trem,tles, one can calculate the dis
lance between them. On coast de-
fences the base Of the triangle is per-
manent, with fixed objects to mark its
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 stu
atlons 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. 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 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
thematlcal ability, but it is said to be
absolutely accurate and the apparatus
is SO sensitive and regulated to such
a fine degree that by turning a kew a
monster gun weighing a hundred tons
can be instantly adjusted SO that with
a given quantity of powder it will
carry projectile of a given weight
| exactly the distance which the range
nnder has determined. OF course. the
| gunner must know the contents of his
cartridge, because that is 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-finder is. how
ever. great deal more accurate than
the human eye, and persons with de-
fective vision will often insist that q
gun is badly aimed and 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
to use them at that distance, because.
owing to the curvature of the earth. It
would be impossible to see the target
a man in 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 a glass can
| see eight or nine miles. A man at the
masthead can see ten or twelve miles.
but very indistinctly, and that is the
limit Of human vision on G level sur
face.