The Abbeville press and banner. [volume] (Abbeville, S.C.) 1869-1924, 1876-10-25
RIFLE SHOOTING.

RIFLE SHOOTING.
Din1culties the Marksmen Must Overcome
Elevation and Wind Allowance-.Efects
OF atmospheric Resistance on the Pro-
~Iectilcs.
Notwithstanding the popular interes:
in the rifle contest ct CrcedmoCr, very
few general readers, says the New York
Herald, have any correct idea OF the
technique Of rifle shooting and III" mar
yeiuus perfection to which it Las been
brought. OF course the ordinary Oh.
server forms some estimate of the diff
Guilty of hitting the small black speck on
the target which is called the bull's-eye
and is amazed to SEQ the marksmen put
ting bullet after bullet into it with a
precision which approaches the miracu-
lous. He measures the first by reference
to the great distance of the marksman
from the target and the size of object
aimed at, and the other he regards as
wonderful because of the skill displayed
in the face of the difficulties already
named. Beyond this he forms no opin.
ion of the craftsmanship and contents
himself with applauding the results as
deserving of great praise.
Take q man of the steadiest nerve and
the keenest eyesight, but possessing nc
knowledge OF the laws governing the
flight of projectiles, and put in his
hands the most perfect rifle that can be
manufactured; then place him before
the target at say five hundred yards,
and the chances are that in nine shots
out of ten he will fail to hit the target at
all, not to say the bulls eye. This is
because there is a knowledge necessary
to good craftsmanship, which is entirely
independent of mere good aiming and
clear vision. He would probably con.
tent himself with lying down and
steadily directing his rife at the bulls
eye without any regard to the operation
of the forces acting N a ball during its
fight, and would expect that it should
follow a direct line to the object aimed
at.
But in this he would be entirely at
fault, and his eye would not be greeted
by the markers disk at the butts, show
ing that the shot was "on." A puff Of
dust from the ground a considerable
distance in front of the target would in.
form him that his bullet fell short of its
mark. On inquiry as to the Of
his failure he would receive from those
who knew all about it the following in.
formation:
When a bullet leaves the muzzle Of q
rifle in it's flight toward the target three
forces act upon it and influence its
movement until it is checked by striking
a resisting object. The first is the force
of propulsion, impaired in the gun by
the energy of the expanding gas, gene
rated by the explosion of the charge.
This force rcvoIves direction from the
barrel of the gun, and if no other force
acted on the ball it would travel on an
exact line in continuation of that of the
axis of the barrel. The second force is
that of gravity, which tends to draw the
bullet downward toward the earth with
a constantly increasing velocity. Con.
sequently, instead Of following a straight
course coincident with the axis of the
barrel it falls continuously from that
line during it's flight, The third force
is that represented by the resistance OF
the air, which tends to retard the bullet
in it's progress toward the target and
acts in proportion to the square Of the
velocity of the bullet and to the density
of the atmosphere itself. Thus, instead
of ~traversing along the direct or the
shortest line to the object, it follows q
course which is theoretically parabolic,
but actually, and by reason Of the at
mospheric resistance, q modification OF
that curve.
In order, therefore, to insure the
fight of the bullet over the full distance
between the rifle and the target it is nee
essary to elevate the direction of the
barrel, so that the %projectile will be
raised during its flight a sufficient height
over the plane in which are located the
point of departure and the object
sought to be hit to compensate for the
loss by gravitation.
To regulate the angle, q tangent scale
is fitted to the breech of the gun, and to
this scale is attached the movable real
sight with which, with the vertically i'm
movable muzzle sight, the line of sight
or aim is determined. The scale is di'
vided into degrees, minutes and seconds.
the latter subdivision being obtained by
means of q vernier scale attached fol
the purpose. The fine division of the
tangent scale is necessary in order tc
regulate the changes in elevation re-
quired for variations of range and the
resistance of the atmosphere. In the
former case, let it be supposed that 9
marksman hits the bull's.eye at an eight
hundred yards range, with a certain ele'
walton OF the rear sight on the tangent
scale. Ii he desires to hit it again al
$50 yardshe must increased the elevation,
and decrease it for a distance of TIE
yards. Thus the utmost accuracy car
only be attained by a fine adjustment Of
the sights.
The influence of the wind on the
fight Of a bullet is very great, and, when
the wind is variable, is constantly chang
ing. On a perfectly" calm day at Greed
moor the line of sight is in the same
vertical plane as the line of fire; that is,
the marksman adjusts his muzzle sight
to correspond exactly in relation to the
breech sight with the axis Of the rife
barrel. He shoots "dead on" rs it is
termed, making no allowance for the
force of the wind. If, however, a wind
is blowing in the same direction as tbs
line Of sight that is toward the target,
the elevation of the breech sight must
be lowered in proportion to the force Of
the wind, because the moving air cur
rent has a tendency to lift the ball, moi
actually, but relatively, by delaying the
fall due to gravity within the period Of
fight. On the other hand, if the vino
blows toward the marksman the eleva'
ton must be raised to compensate fol
the increased resistance created by the
wind to the progress of the bullet, which
is in addition to the normal resistance Of
the air at rest.
When the wind blows across the line
of fire it causes the bullet to drift in the
same direction as the wind blows, and
while it may not necessitate an altera'
ton Of elevation it compels the ri1emar
to move the muzzle sight 80 many points
over on the barrel with the wind, &c
that the limo of fire will diverge from
the line of sight, and thus compensate
for the drift of the bullet.
An oblique wind, with or against the
ball, creates a further complication OF
the sighting. The former compels 9
reduction of the elevation and IN allow
onoa for Wind uhila tho lotkar necesai