The Morris County chronicle. [volume] (Morristown, N.J.) 1877-1915, 1898-08-26
THE FLIGHT OF A BULLET.
a Krag -Jogensen Goes Mile in Three
seconds.


The velocity ranges from 1900 to 5000
feet per second. 1t is computed that
the average velocity of the larger guns
per second. To the uninitiated the
way in which this is found out should
be of interest.
In the first place, it may be stated
that one cannot time projectile as
bne would horse Some of them can
be seen as they rush through the air.
lit is favorite amusement during the
battery drill with the old seacoast
guns at West Point to stand behind
and slightly above the gun, and watch
the projectile from the moment it
leaves the muzzle until it strikes the
target painted on old Gro Nest noun
tain, about mile away. Spectators
with good eyesight can also see the
shell fired from the large mortar rise
to the highest point of its course, and
then descend with a rush upon the
mountain top, mile and half away,
where it bursts into many pieces.
1t is reported that during the bonn
bardment of Santiago the shells of the
cruiser New Orleans could be followed
by the eye. This was largely due to
the use of smokeless powder, which
permitted clear vision.
But in case of smaller projectiles,
with greater velocity, it is impossible
to see them during fight. But wheth-
er they can be seen or not, it is quite
out of the question to time them as
one would race, by simply using the
eye and stop watch. The least hest
tation in pushing the spring would
make a difference of hundreds Of feet
in the distance travelled. Errors such
as these would make the results of no
practical value.
Our small arm shoots bullet only
one-third of an inch in diameter,
mile in three. 1t goes SO fast that
it becomes hot to the touch, due to the
resistance of the air which it pushes
aside. Strange to say the heated bull
let will cauterize the wound of its own
making, and few of the wounded in our
war with Spain bleed to death unless
struck in vital spot.
The projectile has, beside the for
ward velocity, rotational velocity,
which is given to it by the rif1ipg Of
the gun. Otherwise since its length
is much greater than it's diameter, 1t
would soon begin to turn end on. The
rifing prevents this by causing the
bullet to bore a path through the air,
and the higher the forward velocity
the higher, too, must be the rotational.
This turning over and over would de-
stroy the range and the accuracy Of the
gun.
The determination Of the forward
velocity is now made with extreme
accuracy. The knowledge of it is of
the utmost importance to military
science. Various methods have been
adopted for it's determination within
the gun, as well as at various points
of the trajectory.
The following method is the one
adopted by all nations for finding the
velocity of a projectile at any point Of
its path after leaving the muzzle of
the gun:
Two screens, so closely strung with
copper wire that projectile in passing
through must break one or more of the
strands, are placed fifty yards apart.
The wire on each screen is connected
with a battery, which sends current
through it and two instruments, one
called disjunctor, the other the
chronograph. Although both circuits
pass through these instruments, yet
they are kept distinct and separate.
The chronograph answers the pur-
pose of stop watch of greatest accur-
acy. Two bars are held up by electric
magnets; the currents flowing in one
magnet also flow through its respec-
tive screen, while the current of the
other passes through the second screen.
The disjunctor is an instrument which
is used to break both circuits at the
same instant AS soon as this is done
the bars fall, since the electro magnets
cease to act when there is no current
flowing through them. The bar con-
nected with the first screen falls upon
small platform, which releases a
wedge-shaped piece of metal. This
strikes the bar connected with the
second screen, leaving wedge-shaped
slit in it as line Of reference during
the experiments.
This being done, the currents are
established again, and the rods placed
once more under the influence of the
electromagnetic. Let 32-inch rife
whose muzzle velocity is to be found
be placed in front of the first screen.
The gun is aimed, fired and its pro-
jectile passes quicker than the roar
of the discharge through the first
screen, breaking some of its wires; In
another instant it is through the Sec
ond screen, destroying its electric cur
rent, and at last finds resting place
| in some distant sand pile.
The break in each circuit is COM
municated to all parts of the line in
stantly. If the times at which both
occur can be determined the problem
is solved. For instance, let the time
it took to pass over the so yards be .075
OF a second. Then, dividing the one
by the other gives 1000 feet per second
as the velocity of the projectile.
The time is found by accurately
measuring the distance between the
first dent, the origin, and the second
dent, caused by the projectile break