Richmond dispatch. [volume] (Richmond, Va.) 1884-1903, 1898-07-22
MODERN PROJECTILEs.
Velocity of Shells Reach a Maximum
of 5000 Feet Per Second.


ranges from l500 to 1900 feet per second.
1t Is computed that the average velocity
OF the larger guns on the cruiser New
York IL 100 feet per second. To the un-
initiated the way in which this is found
out should be of interest. In the first
| place it may be stated that one cannot
| time a projectile as one would a horse.
Some OF them can be seen as they rush
through the air. 1t Is a favorite amuse-
ment during the battery drill with the
old seacoast guns at West Point 10 stand
| behind and slightly above the gun and
watch the projectile from the moment it
| leaves the muzzle until 1t strikes the
target painted on old Crows Nest Noun
tain. about mile away. Spectators with
| good eyesight can also see the shell fired
| from the larger mortar rise to the height
| Of its course and then descend with n
| rush upon the mountain top, mile and
| half away, where II bursts into many
pieces. 1t is reported that during the
| recent bombardment 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, II is impossible 10 see
them during a fight But whether they
can be seen or not, 1t is quite out of the
question TO time them as one would
race by simply using the eye and a stop
watch. The least hesitation IN pushing
the spring would make a difference OF
hundreds Of feet in the distance travelled.
Errors such as these would make the re-
suits Of no practical value. Our small arm
shoots bullet only one third of an inch
in diameter. which travels 1000 feet in q
second, or mile in three. 1t goes so fast
that it becomes hot to the touch. due 10
the resistance Of the air which 1t pushes
aside. Strange 10 say, the heated bullet
will cauterize the wound of it's own
making. and few of the wounded in our
war with Spain will bleed 20 death, unless
struck In vital spot. The projectile has.
besides the forward velocity, rotational
velocity, which is given to il by the
riiiing OF the gun. Otherwise, since its
length Is much greater than its diameter,
1t would soon begin TO turn end on The
rifiing prevents Ihis by causing the bullet
to bore path through the air, and the
higher the forward velocity the higher
too must be the rotational. The turning
over and over would destroy the range
and the accuracy of the gun.
Inc determination Of the forward We
locity IL now made with extreme accu-
racy The knowledge of II is OF the ut
most Importance to military science. 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. 1t is so
simple that brief explanation Of II will
make it ineligible to all. Two screens.
so closely strung with copper wire that a
projectile in passing through must break
one or more of the strands, are placed
fifty yards apart. The wire Oh each
iS % tt,tth hatt
sends current through it, and two in.
struments. 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 purpose OF
stop watch of the greatest accuracy.
Two bars are held up by the electric mag
nets; the currents flowing In one magnet
also flow through It's respective 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 electromagnetic cease to act when |
there is no current flowing through them. |
The bar connected with the first screen
rails upon small platform, which re-
leases a wedge-shaped piece of metal. !
Ihis strikes the bar connected with the
second screen, leaving a wedge-shaped
silt IN II as line Of reference during the
experiments.
This being done, the currents are estab-
lished again and the rods placed once
more under the influence OF the electro
magnets. Let a 3.2-inch rifle whose muz-
zle velocity Is 20 be found be placed IN
front OF the first screen. The gun Is
aimed, fired, and It's projectile passes
quicker than the roar of the discharge
through the first screen. some of its wires.
in another instant it is through the Sc
cond screen, destroying its electric cur
rent, and at last finds a resting-place I'm
some distant sand-pile. The break IN /
each circuit is communicated TO all parts
OF the line instantly. II the times at
which both occur can be determined the
problem is solved. For instance. let the
time 1t took to pass over the fifty YARDS
be 90 of a second. Then. dividing the
one by the other, gives 1000 feet per se-
cond as the velocity of the projectile.
The time is found by accurately mea-
surfing the distance between the first dent
the origin, and the second dent. caused
by the projectile breaking the circuits at
different times. To illustrate the princi-
pie involved: II the projectile be of low
velocity the distance will be greater than
II II travelled at a high rate OF speed,
since the first rod would have q longer
time to fall before the second starts. IL
the distance be, say. one inch then from
the law OF falling bodies the time for that
fall can readily be found, and this will
pc the time II took the projectile TO travel
over the fifty yards between the screens
Expressed automatically, this law is
hat the time of fall Is equal TO twice the
distance OF fall divided by gravity.
So accurate is this determination that
he velocity OF the swiftest projectile can
Do found 10 the fraction OF foot. This
means the measurement OF time 10 the
housandth part OF n second-a fraction
90 small 10 comprehend. The trajectory
II projectile is the path 1t travels. ana
he way Of discovering IL is simple.
screens are put up in line at intervals 1
Il 100 yards. These are covered with
arget cloth. and are so built that they ,,
an be raised or lowered by ropes run
ling over pulleys. which are in the frame {
work. that supports the screens The rifle
; put In a wise. the muzzle being al the II
anne height as the distant bulis-eye.
Jpon the discharge Of the gun the bullet
gill leave hole In each screen, and 7
rom these Its trajectory Is easily de-
uced and transferred TO paper. 1t is {
artly on account OF these FIAT trajectories !
hat such terrible loss Of life is expected I
q Q great vfr. Ii