The Sun.
London, England, 1862-03-10 00:00:00

ORDNANCE.

Major Owen, professor of artillery at Woolwich,
delivered a lecture at the Royal United Service In-
stitution on Friday, on " The motion of projectiles
fired from rifled ordnance, and the advantages ob-
tained by the employment of such prices." He ex-
plained, in the first place, the different effects
produced by the resistance of the air to the motion
of round shot and of elongated projectiles. As
round shot present a greater surface to the air than
such projectiles of the same weight, the velocity
with which they are fired becomes more quickly
retarded, and this retardation increases in greater
proportion with the increase of velocity. For this
reason a round shot that is fired with an initial
velocity of 1,600 feet in a second is reduced at a
distance of about 600 yards to the same velocity as
an elongated shot of the same weight that is pro-
pelled from a rifled gun at the rate of 1,200 feet in
a second. The continued greater resistance of the
air to the progress of the round shot diminishes its
velocity at longer ranges to less than that of the
projectile, and the latter is consequently propelled
much further than the round shot, though the latter
was fired with greater initial velocity, by means of
a larger charge. To enable the elongated projectile
to possess this advantage it is necessary that it
should be propelled in such manner as to continue
to present its end, or smaller surface, to the air
throughout the course of its flight, and this is done
by giving a rapid rotatory motion on its longest
axis, by rifling the cannon. The notion commonly
entertained that an elongated projectile will main-
tain a position parallel to that with which it is fired
was shown by Major Owen to apply only to pro-
jectiles fired at low velocities and without rapid
rotation on,their longer axes. To illustrate this a
wooden cylinder, shaped like an ordinary projectile,
sgiivriennto it. The gun was
spring
considerable angle,
gun, rotary motion
wp
havingoains tped propelled
upwards
pee lnwl e
adrds
previouslyfroamt a a
projectile was seen to maintain in the course of its
flight a position parallel to that of the elevated gun,
but it kept that position steadily. The mimic pro-
jectile was then propelled without having had ro-
tary motion given to it, when it was seen to move
smallest
from sttsuurrnfiancge t
oo uthrough the air in the same position ; but, instead
present
toctihtye and with rapid rota-
tione
of being steady as before, it wabbled. The resist-
ance offered by the air to the projectile, when
alle
round
rsis, causesiresisting, movingt g withpower,
t o greatpre
and
prevents
and rotating on its shorter axis. This effect, as
well as the regulation of the direction of the pro-
jectile i
positionl e
gravity. If it be placed
near the fore part the projectile descends too per-
of descent,the e
ntre of depende also in some degree on
t in its
pendicularly, and it is found in practice to be best
to place the centre of gravity near the middle of
the projectile. Major Owen illustrated the effects
of the resistance of the air, and of the velocity of
rotation on projectiles, by means of a gyroscope,
against which a strong blast was directed, to imi-
tate the effect of the air's resistance. By this in-
genious apparatus the influence of the resistance
when a projectile is moving with different degrees
of velocity, and when propelled with the fiat or
with the rounded end foremost, were exhibited.
Major Owen stated that the results of numerous
experiments with projectiles of various forms had
proved that those with oval-shaped ends meet with
less resistance in their flight through the air than
those with conical or with spherical ends. A diffe-
rence is also observed in the direction of the projec-
tile when the rotary motion is given from left to
right, or the contrary; for in the one case the pro-
jectile swerves towards the right, and in the other
towards the left. Major Owen pointed out the ad-
vantages of rifled ordnance under various circum-
stances, which waists principally in obtaining a