and _a_ as 26,648 ft. and 9114·1 ft. respectively; and as _c_/_b_ =
_cosine_ 20°, we have _c_ = 26,648 × ·9396926 = 25040·8 ft., which is
the _range_. The trajectory will be a curve (parabola) symmetrical on
each side of a vertical line half-way between A and B, and the length of
this line within the triangle will be equal to half of _a_, and in half
of 23·7927 seconds the projectile, supposed to move only along the line
AC, would reach the point where this vertical axis intersects AC. If
during this half-time it had been falling from rest at the same
intersection, it would have reached a point below by a space just one
quarter of CB (the spaces fallen through being as the _squares_ of the
times), and therefore at this its highest point its distance above AB
would also be one quarter the length of _a_ = 2278·525 ft., which
distance is called the _height_ of the trajectory; and the descending
curve being in every respect symmetrical to the ascending branch, the
angle at which this would be inclined to AB would be 20°, but in the
opposite direction to BAC, while the velocity would be the same as at A.
We may now compare these results with those calculated when the air
resistance is taken into account:—
┌─────────────────────────────────┬───────────┬───────────┬───────────┐
│ │Without air│With air │ │
│ │resistance.│resistance.│Difference.│
├─────────────────────────────────┼───────────┼───────────┼───────────┤
│Time of descent │23·7927 │22·61 sec. │–1·18 sec. │
│ │secs. │ │ │
│Angle of descent │20° │23° 49´ │+3° 49´ │
│Velocity of descent │1120 │868·8 │–251·2 │
│ │foot-secs. │foot-secs. │f.-s. │
│Range │25040·8 ft.│20,622 ft. │–4418·8 ft.│
│Height of trajectory │2278·5 ft. │1989 ft. │–288·5 ft. │
└─────────────────────────────────┴───────────┴───────────┴───────────┘
With the air resistance the trajectory will no longer be a symmetrical
curve: its highest point, instead of being on the vertical line midway
between A and B, will be on one 1,050 ft. nearer to B than to A, and the
descending branch will be steeper than the ascending. The total time, it
will be observed, is less, although the final, and therefore the mean,
velocity, is also less; but this shortening of the time is due to the
trajectory itself being much less in length. The range of the projectile
is decreased by 4,418 ft., or 1,473 yards, or more than four-fifths of a
mile. The loss of velocity at the descent is very notable, and the
reader will find it interesting to calculate the corresponding loss of
energy by the formula already given.
The reader should now easily understand that the projectile from a rifle
or gun discharged horizontally through airless space at the height of
16·1 ft. above a level plain would strike the ground in one second at a
range or distance from the gun exactly equal to the initial velocity, or
if the gun were on a tower and its axis 64·4 ft. above the plain, the
range would then be 2V. It will be seen therefore that, corresponding to
the range intended, there must be in general a certain inclination given
to the axis of the piece in aiming, and this is done by means of the
_sights_, one of which near the muzzle is usually fixed, while that next
the breech is adjustable by sliding along an upright bar, which is
graduated so that the proper elevation may be given for any required
range. These graduations are made from experiments, and of course have
reference only to some standard quantity and quality of ammunition and a
standard of weight, shape, and material in the projectile. Sometimes
large pieces of ordnance are laid by elevation in degrees, etc., marked
on their mounting, the angles being taken from a table prepared for that
particular gun and ammunition, from experiments at different ranges.
After these generalities about fire-arms we may enter upon certain
particulars about the construction of some varieties, beginning with
_THE MILITARY RIFLE._
[Illustration:
FIG. 82.—_Muzzle-loading Musket and Rifles_ (_obsolete patterns_).
A. Brown Bess and Bayonet; B. Brunswick Rifle; C. Enfield Rifle and
Bayonet.
]
In Fig. 82 are represented the muzzle-loading musket and muzzle-loading
rifles which formed the regulation weapons of the British infantry from
the beginning of the century up to the year 1864. Somewhat slow in its
earlier stages was the development of the modern military rifle from the
old smooth bore musket with its flint-lock, which was the ordinary
weapon of the British and other armies up to nearly the middle of this
century. Partly, perhaps, owing to the inherent conservatism of
government departments, and partly to the very serious outlay involved
in arming all the troops of a nation with a new weapon, it has happened
that many improvements in small arms were in use as applied to sporting
guns, long before they were adopted in the regulation weapons of armies.
The advance towards the modern arm of precision has been made along all
the several directions that converge in the latest product, and it may
be said that the most obvious of these are spiral rifling,
breech-loading, and improved ammunition. The improvements in any one of
these particulars would have been of little advantage unless the others
had been kept in line with it. How long antiquated systems may continue
in use may be illustrated by the case of the flint-lock, which was
retained in the British army from the time it superseded the old
match-lock, in the latter part of the seventeenth century, down to
almost the middle of this present nineteenth. It is quite possible that
not a few readers still in their fifties may never have seen a
flint-lock outside of a museum, yet this was the firing apparatus of the
weapon that used to be affectionately known to our soldiers as “Brown
Bess,” and that for a century and a half continued the regulation arm of
British troops helping Wellington to win his victories, and superseded
by the percussion musket only in 1842. The “Brown Bess” of the earlier
part of the century had a smooth-bore barrel of three-quarters of an
inch diameter (0·753 inch), and 39 inches long; this musket weighed,
with its bayonet, 11 lbs., 2 oz. The bullet was spherical, and made of
lead, in weight a little over one ounce. The diameter of the bullet was
slightly smaller than the bore of the barrel, because a closely fitting
ball could not be used, on account of the great force required to push
it home with a ram-rod. The bullet was therefore wrapped in loosely
fitting material, called a “patch,” and this made the gun easy to load,
even when the barrel was “fouled” by the solid residues that always
remain after the explosion of gunpowder. “Brown Bess” was credited with
a range of 200 yards, but its want of accuracy was such that the soldier
was directed not to fire until he could see the whites of the enemies’
eyes. But in 1800 one or two British regiments were armed with the
muzzle-loading rifle known as Baker’s, and again in 1835 these were
provided with the _Brunswick rifle_. These regiments afterwards became
known as the Rifle Brigade. The bullets in both cases were spherical,
and as the earlier pattern had a seven-grooved barrel, there was so much
difficulty in introducing the bullets into the muzzles that mallets had
to be used. The bullet of the Brunswick rifle was encircled by a
projecting band, which fitted into two rather deep grooves diametrically
opposite to each other in the barrel. This bullet, wrapped in some
slightly greased material, could be readily dropped into the muzzle, and
rammed home without difficulty. Moreover, whereas in Baker’s rifle the
grooves made only a quarter of a turn in the length of the barrel, the
grooves of the Brunswick rifle made more than one complete turn. This
was so much an improvement on “Brown Bess” that the effective range was
more than doubled. For the rank and file of the infantry regiments the
flint-lock smooth-bore musket was, however, the regulation weapon until
1842, when it was superseded by the percussion musket. The
percussion-cap is now comparatively little used, as, since the
introduction of cartridges containing their own means of ignition, it is
rapidly becoming a thing of the past. The copper percussion-cap, in the
form it still retains, was invented about 1816, and was universally
adopted for sporting-guns a long time before it was used for the
military weapon. In 1842 the percussion musket was definitely adopted as
the weapon of the British army, but up to that date the flint-locks
still continued to be made at Birmingham.
The barrel of the percussion musket then issued was shortly afterwards
rifled, when about the year 1852 the Minié system was adopted, and the
Government awarded to M. Minié, a Frenchman, the sum of £20,000 for the
bullet he had invented. What the meaning of this improvement was may now
be explained, and we must begin by mentioning the various forms of
grooving, or, at least, such forms as found some approval during the
present century, for grooved barrels had been tried long before. At
first the grooves appear to have been intended merely to receive the
fouling, and these were often made without any twist or spiral, but
parallel to the axis of the barrel. The grooves are hollow channels of
greater or less depth, and of various forms; square, triangular,
rounded, or of such a form that the inner line of a section of the
barrel would present the form of a ratchet wheel. The numbers of the
grooves made use of have varied between two and twelve, or more, and
different rates of twist, or numbers of turns of the spiral in the
length of the barrel have been resorted to, these ranging from half a
turn to twelve turns. The Brunswick rifle had been found wanting in
accuracy, when at length in 1846 General Jacobs proposed the adoption of
the conical bullet with projecting spiral ridges which fitted into
grooves cut in the rifle barrel. The difficulty in using muzzle-loading
rifles consisted in the force required to ram down the bullet, which had
to adapt itself to the grooves, and fill them up so that the gases due
to the explosion of the powder should not escape. If the bullet simply
dropped into the bore of the rifle easily, it did not effectually fill
the grooves, which then became channels of this _windage_, and if, on
the other hand, the leaden bullet was made to fill the grooves from the
muzzle, great force was required, and the time and effort expended in
ramming the missile home, detracted enormously from the efficiency of
the rifle as a military weapon. Mr. Lancaster produced rifles having a
slightly oval, instead of a circular, bore, making, of course, the
necessary twist within the barrel. A bullet of the corresponding
section, but nearly globular, much as if the projecting belt of the
Brunswick bullet had been laterally extended to its opposite poles,
could be easily dropped in at the muzzle, without force being required
to make it take grooves, the barrel being internally smooth throughout.
It was, however, soon found that this easy-fitting ball allowed a
considerable amount of _windage_, and the Minié system was definitely
adopted, in which advantage was taken of a fact observed some years
before by a French artillery officer, who found that an elongated leaden
bullet, if hollowed out at the base, was so expanded by the pressure of
the powder gases that the material was forced into the grooves of a
rifle. Minié made his bullet elongated, pointed in front, and hollowed
out part of its length by a conical space, the widest part of which was
at the base, and was covered by a small iron cup, that, when driven
inwards by the pressure of the gases, caused an expansion of the bullet
by which the lead was forced into the grooves of the rifling. But the
forces operating on the base of the bullet would at times cause the iron
cup to cut the bullet in two, and propel the anterior portion only,
leaving the base in the form of a ring clinging to the rifling. The
military authorities had many comparative trials carried out between the
smooth-bore percussion musket and the Minié rifle. The greater accuracy
of the latter may be inferred from the results of practice made by men
firing at a target 6 feet high and 20 feet broad; when at 100 yards
distance, 74 hits out of 100 shots were made from the musket, against 94
from the rifle; and the superiority of the latter, at longer ranges, was
increasingly marked. Thus at 260, 300, and 400 yards the respective
percentages of hits were for the musket 42, 16, 4½, but for the same
ranges the rifle gave 80, 55, 52.
[Illustration:
FIG. 83.—_The Minié Bullet._
]
Curiously enough, the principle of the expanding bullet had been brought
forward by the late Mr. W. Greener seventeen years before the government
prize was awarded to M. Minié. Mr. Greener’s bullets were of an oval
form, being half as long again as their diameter, with one end flattened
where the lead was excavated in a narrowing hollow nearly through the
bullet. In this opening was inserted the end of a tapering plug of hard
metal, and when the rifle was fired this plug was driven home, and the
lead thus expanded took the grooves, so preventing windage, and giving
range and accuracy; while allowing the piece to be loaded with as much
ease as the smooth-bore musket. The invention, though favourably
reported on by the military authorities at the time, did not receive the
attention it would seem to have deserved. However, in 1857, Mr.
Greener’s claim of priority for the first suggestion of the expanding
bullet was acknowledged by a government award of £1,000.
[Illustration:
FIG. 84.—_Greener’s Expanding Bullet._
]
Sir Joseph Whitworth, having been invited by the British military
authorities to institute experiments with a view to producing the best
type of rifle, with the help of the most perfect machinery, constructed
the barrels with a polygonal bore, a plan which he had before adopted
for large guns. The barrels were accurately bored out to a hexagonal
section, and experiments were made to find what number of turns in the
twist would give the projectile a sufficient rapidity of rotation to
maintain it during its flight parallel to its axis. It was found that
one turn in 20 inches was sufficient, and the projectile was made by
machinery to fit accurately but easily into the rifled bore, so that it
dropped into its place, and the loading could be expeditiously
performed. The bullet was long, compared with the bore, which was made
smaller than before, and it was found that the explosion caused it to
expand sufficiently to fill up the corners of the hexagon, so that there
was no loss from windage. The accuracy of aim of the Whitworth rifle was
superior to that of any weapon of the kind that had, up to that time,
been produced. When officially tried against the Enfield, its mean
deviation at 500 yards range was only 4½ inches, while that of the
Enfield at the same range was 27 inches. Mr. Whitworth had proved the
advantages of using a small bore, an elongated bullet, and a sharp twist
in the rifling; and it was acknowledged that as a military weapon his
rifle was superior to all other arms of similar calibre that had before
been produced. Some doubt appears to have been entertained, however, as
to whether the mechanical perfection of the trial rifles could be
maintained if they came to be manufactured on the large scale, and also
as whether an adequate supply of the polygonal ammunition would be
procurable when required. The Whitworth rifle was never adopted into the
government service, and soon after these trials in 1857, the adoption of
another type of weapon became imperative, as the results obtained by the
Germans with their needle-gun, demonstrated the enormous advantages of a
breech-loading rifle.
[Illustration:
FIG. 85.—_The Chassepot Rifle.—Section of the Breech._
]
The French then adopted the Chassepot rifle (so called after its
inventor), which embodied the same principle as the needle-gun, but with
improvements. This arm has a rifled barrel, with a breech mechanism of
great simplicity, which is represented in section in Fig. 85. The piece
marked B corresponds to what is called the “hammer” in the old lock used
with percussion-caps, and the first operation in charging the rifle
consists in drawing out B, as shown in the cut, until, by the spring, C,
connected with the trigger, A, falling into a notch, the hammer, if we
may so term it, is retained in that position. The effect of this
movement is to draw out also a small rod attached to the hammer, and
terminated in front by a needle, about ½ in. long, at the same time that
a spiral spring surrounding the rod is compressed, the spring being
fastened to the front end of the rod, and abutting against a screw-plug,
which closes the hinder end of F, and permits only the rod to pass
through it. The piece F, which is also movable, has projecting from its
front end a little hollow cylinder, through the centre of which the
needle passes, and this little cylinder has a collar, serving to retain
its position, an india-rubber ring surrounding a portion of the
cylinder, and forming a plug to effectually close the rear end of the
barrel. It will be noticed that the cylinder is continued by a smaller
projection, which forms a sheath for the point of the needle. The
movable breech-piece, F, is provided with a short lever, E, by which it
is worked. The second movement performed by the person who is charging
the piece is to turn this lever from a horizontal to a vertical
position, which thus causes the piece F to turn 90° about its axis, and
then by drawing the lever towards him he removes the piece F from the
end of the barrel, which, thus exposed, is ready to receive the
cartridge. The cartridge contains the powder and the bullet in one case,
the posterior portion containing also a charge of _fulminate_ in the
centre, and it is by the needle penetrating the case of the cartridge
and detonating this fulminate that the charge is exploded. When the
cartridge has been placed in the barrel, the piece F is pushed forward,
the metallic collar and india-rubber ring stop up the rear of the
barrel, and on turning the lever, E, into a horizontal position, the
breech is entirely closed. If now the trigger be drawn, the hammer is
released, and the spring carries it forward, at the same time impelling
the needle through the base of the cartridge-case, where it immediately
causes the explosion of the fulminate. The bullet is conical, and its
base having a slight enlargement, the latter moulds itself to the
grooves with which the barrel is rifled. When the piece has not to be
fired immediately, the lever is not placed horizontally, but in an
inclined position, in which the hammer cannot move forward, even if the
trigger be drawn. The Chassepot has an effective range of 1,093 yards,
and the projectile leaves the piece with a velocity of 1,345 ft. per
second, the trajectory being such that at 230 yards the bullet is only
18 in. above the straight line. The piece can be charged and fired by
the soldier in any position, and it was found that it could be
discharged from seven to ten times per minute, even when aim was taken
through the sights with which it is furnished, and fourteen or fifteen
times per minute without sighting. The ordinary rifled musket, which
this arm superseded, could only be fired twice in a minute, and could
only be loaded when the soldier was standing up.
Other nations followed either by adopting as their infantry arm some
form of breech-loader, or by converting their muzzle-loaders into
breech-loaders as a temporary expedient, pending the selection of some
more perfect type. When in 1864 a committee which had been appointed to
investigate the question of proper arms for our infantry, recommended
that that branch of the service should be supplied with breech-loaders,
our Government, considering that no form of breech-loader had up to that
time been invented which would unequivocally meet all the requirements
of the case, wisely determined that, pending the selection of a suitable
arm, the service muzzle-loaders should meanwhile be converted into
breech-loaders. The problem of how this was to be done was solved by the
gunmaker Snider, and in the “Converted Enfield” or “Snider” the British
army was provided for a time with an arm satisfying the requirements of
that period. This change of weapon was effected at a comparatively small
outlay, for the conversion cost less than twenty shillings an arm. The
breech action in the Snider consisted of a solid piece of metal which
closed the breech end of the barrel, and, being hinged on the right-hand
side parallel to the barrel, could be turned aside, making room for the
insertion into the conically widened bore of a metallic cartridge case,
invented by Colonel Boxer, which contained the projectile, the powder
charge, and the means of ignition in itself. A short backward movement
of the breech-lock caused a claw acting on the base of the spent
cartridge case to withdraw it from the barrel, and then the reaction of
a spring brought the breech-block back into position, after insertion of
a new cartridge. This cartridge proved very effective in increasing the
range and accuracy of the weapon. It should be mentioned that all the
breech-loading mechanisms are provided with arrangements by which the
metallic cases of the spent cartridges are automatically extracted from
the barrel. The authorities having, in 1866, offered gunmakers and
others handsome prizes for the production of rifles best fulfilling
certain conditions, nine weapons were selected out of 104 as worthy to
compete. No first prize was awarded, but the second was given to Mr.
Henry, while Mr. Martini was seventh on the list. In order to obtain a
weapon fulfilling all the requirements, a vast number of experiments
were made by the committee appointed for that purpose, as to best
construction of barrel, size of bore, system of rifling, kind of
cartridge, and other particulars, and assistance was rendered by several
eminent gunsmiths and engineers.
[Illustration:
FIG. 86.—_Section of Martini-Henry Lock._
]