to admit; and that guns forged of hoops, rings, and bars, in smaller
sections, are free from this objection, I am also ready to admit. These
guns are, however, liable to objections equally fatal, both as regards
their enduring and projective powers, as I shall presently show.
Experience proves that brass guns are inferior, both in sharpness of
shooting and in range, to cast-iron guns: this is undoubtedly
attributable to the greater softness of brass than of cast iron; and for
the same reason a wrought-iron gun, though made as sound as one of cast
iron, would be inferior in these two important points. But when a
wrought-iron gun is composed of many particles imperfectly secured (and
no mechanical force is sufficient to secure perfect cohesion in large
masses), the wrought becomes doubly inferior to the cast gun: a shot
projected from such a gun starts from an unsound base; a large portion
of the explosive force is absorbed by the variety of sections composing
the gun, to the injury both of the accuracy and length of range of the
projectile. The softer metals cannot be beneficially used in the
construction of large guns, because they destroy the force of the
expellant without making any equivalent return; and the softer the metal
and the greater its substance, the more clearly is this important fact
demonstrated. Thus, in experiments made with large cannon for increasing
the weight of the gun beyond a certain proportion to that of the
projectile, a gun of ten tons weight and ten inch bore would not exceed
in range a gun of five tons, if the charge of powder were the same; on
account of the indisputable fact that much more force of the expellant
is destroyed, whilst more than double the force is absorbed for the
recoil of the ten ton than of the five ton gun; and the loss from these
two causes must materially affect the flight of the projectile, though
fired at exactly the same elevation.
The great defect which experiment shows to exist in the hoop-and-stave
wrought iron gun, and which renders the gun self-destroying, is
separation at points between the trunnions and cascable of the gun. The
force acting first upon the breech, it yields, and the force is then
brought to bear upon the longitudinal portion of the gun behind the
trunnions; the staves have thus to bear the first strain, and, after a
few shots, become elongated. An opening of the hoops at their junction
with each other (most frequently between the breech and trunnions)
begins, after a very few shots, to be distinctly visible, and increases
at every discharge, until further proceeding amounts to madness, or
recklessness of human life.
That enormous engine, Mallet’s monster mortar, of which I give an
engraving on page 100, clearly proves this to be the case. It will be
observed to be constructed with a solid cast iron breech end, the
dimensions of which will be seen by referring to the engraving. Abutting
upon this are a succession of wrought iron hoops, ingeniously inserted
into each other, and more firmly secured by six outside staves of great
dimensions, which, at the muzzle ring, pass through openings in the
muzzle ring, with heads like enormous rivets. The binding power is given
by “quoin-like” wedges, driven through the opposite end of the stave,
beneath the projection of the cast breech, giving power to tighten the
longitudinal binders by a blow when required.
[Illustration: Mallet’s Mortar.]
DIMENSIONS.
Tons. cwt. qrs. lbs.
Cast iron base with wrought iron breech shrunk
into bore 21 19 0 2
Wood carriage complete, with wrought iron screw
and spanner for elevating mortar 8 8 0 14
Bottom part of mortar to fit on top of the breech 7 5 3 23
Part of mortar (a ring) to fit on the top of the
above 5 8 3 23
Do. do. do. 3 0 2 13
Muzzle ring 1 2 3 12
Wood ring 0 0 1 0
Wrought iron ring 0 4 3 4
Wrought iron conical ring to fix on top of muzzle
ring 0 3 3 25
T-headed bolts, with gibs and keys for fixing
mortar to base: may be called outer staves 1 16 2 0
Wood-wedges, &c., for elevating 0 13 3 22
Outer pin, with cross for turning mortar round 0 8 3 14
------------------
Total weight 50 13 2 21
Weight of shell unfilled, 26 cwt. 2 qrs.; diameter, 36 inches.
This is notorious as a monster failure, even with a charge of powder
amounting to only one half what the projector fondly hoped would be
perfectly harmless in its effects. This Brobdignagian toy has proved to
be fearfully expensive, the cost having been estimated at eight thousand
pounds. It has, I believe, been the largest and most expensive
experiment indulged in by the noble “projector,”[6] and I sincerely hope
it will be the last.
[6] Lord Palmerston.
The preceding pages will have done much to remove from an unbiassed mind
any favourable impression of the advantages expected to result from the
use of wrought-iron cannon. The knowledge of this subject, even among
talented and scientific men, appears to be at a very low ebb, as is
evinced by the multitude of failures that have taken place; not one
success of any moment has as yet been attained, and not a discovery has
been made worthy of being chronicled.
* * * * *
Having enlarged thus much on the qualities of a metal which it is
certain can never supersede the use of cast-iron, even though it be
freed from the defects found practically to exist in our present
constructed iron artillery; and having also alluded to the fact that the
_form_ has much influence on the durability of cast-iron guns, I now
proceed to the more important point of the qualities of cast-iron
itself.
Little doubt exists that guns cast a hundred years ago were more durable
than those of more recent formation; it is evident, therefore, that
apart from mere form, some material depreciation must have taken place
in the quality of the metal. The use of hot blast-furnaces, better
fluxes, and improved chemical knowledge in the reduction of metallic
ores, though highly profitable in a commercial point of view, doubling
the products of our mines, and enriching their proprietors, has,
unfortunately rendered English cast-iron perfectly unfit for the
formation of cannon, if increased range and greater strain by high
elevation are to be the order of the day.
The durability of Russian cast-iron is unquestionably greater than that
manufactured in England. Some cause must exist for this; and the
question arises, is the ore superior to ours, or does the superiority of
Russian iron depend on their method of smelting? The latter is, we
believe, the cause of the superiority of Russian iron; for experiments
show that Russian ore, smelted in an English furnace, yields the same
kind of cast-iron as is produced from the ore found in England. The
inference, therefore, is plain, that the difference in the process of
smelting makes all the difference in the quality of the iron.
Two thousand years ago the Romans, or their dependents, smelted iron in
the county of Durham: vast accumulations of slag exist there at the
present time; and thousands of tons have been beneficially re-smelted by
two adjoining iron-works, and a percentage of iron obtained sufficient
to prove that the Romans were little indebted to fluxes or hot blasts
for the quality of iron they obtained. The Russians cannot boast of
these adjuncts any more than the Romans: the old agents, wood and
energy, are alone employed in the smelting of their ores; and in the
absence of scientific aids, though they obtain a much smaller aggregate
quantity of metal, yet it is undoubtedly of a much superior quality.
With the Romans, also, the yield was meagre, but the quality was good;
now, however, circumstances are reversed, quantity, not quality, being
the order of the day.
The use of coals instead of wood in the process of smelting has
introduced a mixture which is very prejudicial. Most of the coal, even
from our very best mines, contains a large quantity of pyrites, or
bisulphuret of iron, which, combining with the cast-iron, injures it to
an incalculable extent.
These facts fully explain why our cast-iron guns are not so good now as
formerly. Select the most suitable mine in the kingdom, erect a furnace
on the most improved principles, employ wood fuel only, avoid fluxes and
hot and cold blasts, and be content with the small amount of metal
produced, and beyond all doubt the quality will be all that the most
sanguine founder or artillerist could wish.
Thus the inferiority of our cast-iron guns has been accounted for, and a
method suggested, which, if efficiently carried out, would effect the
desired improvement.
* * * * *
We are indebted to Krupp for the first suggestion of, as well as the
first attempt to introduce, a cast steel gun of greater durability and
power than the best cast-iron gun which has yet been manufactured.
Steel, possessing, as it does, hardness to any desired extent, ductility
in an equal degree, tenacity unrivalled, and all the other requisites,
is destined to take the place of all other metals in the construction of
artillery. This metal waits only to be tested; and the greater the
extent to which the trial is carried, the more confident we are that it
will answer every purpose.
Krupp, like many other men with valuable ideas, has been peculiarly
unfortunate in his attempts to carry them out. With a vast amount of
knowledge of the science of metallurgy, he wants more knowledge in the
not inferior science of projectiles; the most important point being to
ascertain the form of gun calculated to be suitable for new metal, of
the use of which, for cannon, the world possesses no antecedent
knowledge.
The only failures Mr. Krupp has made (if they can, strictly speaking,
be so called), have arisen from mal-construction, imperfect form, and
unscientific combinations; defects which might be expected from a mere
novice, though not from experienced artillerists or founders of
artillery. The trial of the only steel gun sent by Mr. Krupp to this
country, was conducted in the most absurd manner, and on wholly
unscientific principles. I will endeavour to convey some idea of this
most extraordinary of experiments. Whether Mr. Krupp was unacquainted
with the durability of his metal, or was persuaded, against his will, to
conduct the experiment as he did, I know not, but the following is what
took place:--
In 1851 Mr. Krupp brought to Woolwich a specimen steel gun of ten-inch
bore, weighing about four tons. He was induced (but why, I am at a loss
to conceive,) to construct a cast-iron jacket, or outer gun, into which
his steel gun was inserted up to the trunnions. The steel gun was
separated from its cast-iron jacket by a space of half an inch in its
whole length, except at each end, where the jacket was fitted to the gun
with a moderate degree of tightness; thus the gun and jacket consisted
of two tubes, one within the other, fastened only at their extremities,
and that by a very slight force. The result, as might have been
expected, was the bursting both of the gun and its case; but that the
steel gun or its jacket would have stood the test, if subjected to it
singly, cannot be doubted. The difference of expansion between the steel
gun and its jacket would be quite enough to account for its bursting.
Had the contact of the two been perfect throughout the whole length,
but allowing half an inch all around for the expansion of the steel gun
in that part which was subjected to the greatest pressure, the very act
of restraining it in other parts so as to prevent equal expansion, would
be perfectly certain to produce a fracture. Mr. Krupp’s friends have
complained loudly of unfair treatment, whether justly or not, no opinion
need now be given; but it is much to be regretted that his experiment
was not carried out on scientific principles. The introduction of cast
steel guns will be the most essential improvement in artillery: and an
extensive series of experiments, extending over many years, during which
time I have manufactured gun-barrels of steel alone, ought to give my
opinion some weight on this subject.
Laminated steel gun-barrels were well known in 1851; but the English
bugbear, prejudice, raised a clamour against them, which was echoed by
interest and ignorance, and thus their general adoption was for a long
time prevented. However, in the short space of seven years, they have
become universally adopted, with the most beneficial results; better
shooting, less annoyance from recoil, less weight to carry, and greater
safety to the sportsman, being the principal. And so it will be with
steel cannon; as a short time will suffice to enable scientific
investigation to remove all prejudices against them.
The external form of cannon is a question of vital importance, but one
which is little understood by artillerists of the present day. Whilst it
is a demonstrable fact that all excessive bulk of cast-iron causes
weakness in proportion to the excess, no effectual steps have as yet
been taken by the Government to ascertain what is the due proportion of
metal which ought to exist in different parts of the gun. The American
authority on naval gunnery, Captain Dhalgren, has paid considerable
attention to this subject; and if the reports on the durability of
American heavy ordnance can be relied on (and there is no reason why
they should not) his investigations have been attended with much
success.
Captain Dhalgren has extended the principle acted upon many years ago by
Mr. Monck; his great improvement consisting in lessening the weight of
iron in front of the trunnions, and adding to that of the breech. In
cannon, as in fowling-pieces, weight in the fore part is useless;
conducing neither to the safety of the gun, nor to the smartness of its
shooting. For endurance, it is necessary that the expansion should be
equal in every part of the gun; rigidity in one part increasing the
strain on the immediately adjacent parts, which, if much reduced, are
thus rendered liable to fracture. The breech has to endure the
lengthened explosion produced by the burning of the gunpowder; and, as
this continues until it has overcome the inertia of the projectile, it
is necessary in all cases that the maximum of strength should be in the
breech of the gun. When the projectile is once in motion the strength of
the tube may be rapidly decreased; the only strain it has to bear is
exerted whilst the projectile is passing over it; and this strain, in
properly constructed guns, becomes of shorter and shorter duration as
the projectile attains its highest velocity at the muzzle of the gun.
The greatest strain a gun has to bear near the muzzle is that produced
by the condensation of the column of air in front of the charge; and in
almost every form of English ordnance the weight of metal here is
greater than is necessary.
The Russian guns which have been brought to this country present the
same superabundance of metal at the muzzle, whilst at the breech there
appears to be a deficiency; and when we take into consideration the
extraordinary reports of their endurance, we must ascribe it to some
other cause than the proper distribution of metal. Their endurance is no
doubt owing in part to the goodness of the metal, in part also to the
form of the breech, to the uniformity of thickness in the sides of the
arch, and, lastly, to the absence of those protuberances called
“reinforce rings.” These rings might with propriety be termed “rings of
destruction;” for wherever irregularities exist in the substance of the
metal, there the waves of vibration are interrupted, and the weak point
then becomes fractured. The science of spring-making in all its
varieties demonstrates the truth of this statement. Leave on a
coach-spring an abutment of metal like a “reinforce ring,” and a few
motions will be sufficient to break it, however well the spring may be
constructed in every other part. The rigidity of this protuberance, by
interrupting the waves of vibration, causes additional vibration in the
adjacent and more yielding part, and thus produces fracture. The same
thing occurs in all ill-constructed artillery: where the vibrations are
checked, there is always a danger of some weaker part giving way. But
the laws which regulate the distribution of vibrations in metal
substances are not yet understood by artillerists, or cannon would be
differently constructed. Those unscientific protuberances called
“trunnions,” which are to be seen in almost every description of gun,
prove the accuracy of my assertions. These protuberances, if
scientifically considered, would soon be discarded, since they tend not
only to the rapid destruction of the cannon, but also exert a most
injurious influence on the direction of the projectile. The most
wonderful shooting ever heard of (and which has been before alluded to)
is partly to be attributed to the absence of trunnions. Trunnions act as
the fulcrum of a scale-beam; they allow the breech and muzzle of the gun
to oscillate, but in an opposite direction to a scale beam. Rifled
cannon can never be correctly constructed whilst any weight impinges on
the gun in front of the first starting point of the projectile; they
must have the fulcrum behind the point of discharge, and the more nearly
in a direct line the better.
Rifled cannon will in some few years be perfectly constructed of cast
steel; the projectile being made of gun metal, _i. e._, ninety-five
parts of copper to five parts of tin, or of lead and its alloys, and at
a probable cost of ten times that of a cast-iron projectile of equal
weight.
Rifled cannon must be elevated by raising the muzzle; no depression of
the breech must occur as by the usual elevating screw; and the recoil
must be received and borne by fastenings and axle in rear of the breech
only. Trunnions and all impinging influences are incompatible with
correctness of fire. The muzzle must be raised in a similar manner to
the raising of a hand rifle, the recoil being thrown backwards, in as
direct a line as possible with that of the shot.
It is only on account of the difficulty of experimenting with rifled
cannon that they are at all behind rifled muskets in point of
perfection. The ardent lover of science is appalled when an experiment
costs hundreds of pounds. We have not a General Jacob everywhere who can
afford to spend a thousand or two in experiments; but, nevertheless, the
lover of science, could he experiment, might attain such extraordinary
accuracy of range, as to blow up a smaller magazine than that of
Kurrachee at four times the distance; and that, too, with a more certain
effect, though with a projectile heavier than several of Jacob’s rifles
tied together. Correct direction is certain in proportion to the
increase of weight; deflection being in the minimum with the heavier
weight, from the well known law of momentum. That astute and energetic
sovereign, the Emperor Napoleon, is pursuing experiments with rifled
cannon; with what result there can be little doubt.
It must be by the use of rifled cannon that our artillery will regain
the place it has lost. A short time will suffice to make the disparity
between our artillery and small arms as great as when we were content
with the six-pounder field gun and old “Brown Bess.” Ranges will only be
ruled by sight, and objects will be hit eventually with as much ease at
5,000 yards as they now are at 1,000. Steel, rifled cannon, and
projectiles of gun-metal will assuredly bring about as complete a
revolution in artillery as the Greenerian rifle and bullet have effected
in small arms.
The form of gun best suited for all purposes has yet to be determined;
and we have pointed out these defects in our artillery with the hope
that some of the great practical philosophers of the present age may
devote themselves to the study of this question. It is nearly allied to
the science of bell-making, and a few more fractures of Big Ben will
extend our knowledge of the subject, and produce a remedy which lies not
very deep below the surface. The laws which should guide us in the
construction of cast steel guns, so as to insure their durability, are
very analogous to those which determine the durability of bells; for the
laws which regulate disintegration of crystalline structures are very
similar. Hitherto the rule of thumb has, unfortunately, been the only
rule observed in measuring out the quantity of metal which shall
surround that portion of a cannon which has to sustain the most violent
concussion.
Professor Barlow many years ago proved, to the satisfaction of the
Institution of Civil Engineers, that the metal in any cylinder decreases
in utility in proportion to the square of its distance from the centre:
that the outside of a gun of the form now used, in fact, is only
one-ninth as useful as the inside; being three times as far from the
centre. If we double the thickness, the outside, being five times as far
from the centre as the inside, will be but one-twenty-fifth as useful;
or in plain English, nearly useless. The reason of this is simple, and I
will endeavour to explain it.
“A bar of cast iron one inch thick each way and 40 inches long will
stretch about one-twentieth of an inch, if a weight of about four tons
be suspended by it. When the weight is removed, the cast iron nearly
recovers its previous form, and is uninjured; but if it be stretched
more, by a greater weight, it is permanently injured.
“A bar of the same thickness, but three times as long--120 inches--will
stretch three times as much, or three-twentieths of an inch, with the
same weight; or if only one-third the weight--one ton and a third--be
suspended, it will stretch one-twentieth of an inch, the same as the
shorter bar.
“If we suspend 16 tons by four bars, one inch thick and 40 inches long,
they will each stretch one-twentieth of an inch only, and remain
uninjured; but if we attempt to do so with two bars 40 inches long and
two 120 inches long, then, when the whole have lengthened one-twentieth
of an inch, the short ones are exerting a force of eight tons, but the
long ones that of only two and two-thirds tons. The weight, therefore,
will still further lengthen the bars, and permanently injure the short
ones; perhaps break them first, and then the long ones.
“This is the way a gun is burst. The inside is a series of bars of iron,
say 40 inches long, in the form of a ring; the outside a series of
rings, representing the bars three times as long.”
Warfare, since the first introduction of gunnery into Europe, has been
like one continued series of experiments for testing the efficacy of our
guns. No description of gun we now possess can lay any claim to
existence fifty years ago: the great majority of our guns now in use are
of a much more recent date.
With one or two exceptions, no artillery has been constructed on any
scientific theory; some alteration has been made, and if a gun of a
certain form and dimensions gave a certain result, then an extension or
emulation of that gun was tried; and if it succeeded a loud cry of
exultation was raised, and the discovery was announced to the world as a
great improvement.
[Illustration: Russian 56-pounder gun.]
[Illustration: 8-inch British gun.]
Colonel Prejudice has invented a vastly improved description of gun;
another guess is made, and so different forms of guns are multiplied.
Can there be a more striking illustration of this than the one which
took place during the late Crimean war? It was boasted that the whole
human race might be exterminated by the new invention; but the
“Lancaster gun” turned out to be most unscientific in its construction,
and most eccentric in its action. Had such a thing as scientific
knowledge in gunnery existed among the artillerists of the day, such a
monstrosity would have been buried soon after its birth; instead of
being allowed to squander large sums of money at every discharge, and
then at last to become a “Whistling Jemmy” for our bluejackets to laugh
at.
The form of cannon no doubt exercises a vital influence over their
durability; bad form and imperfection of material combined, tended to
produce the rapid destruction of our guns during the late important
struggle.
The gun which has been experimented with to the greatest extent, and
which has withstood all trials successfully, is a Russian
fifty-six-pounder; taken, I believe, at Bomarsund. In this gun there are
two great peculiarities; the shape, as will be seen in the diagram,
differs from all our own guns: it is a “chambered gun,” and the metal is
taken away from the outside precisely as the contraction increases on
the inside thus giving an equal thickness of metal in every part, of the
arc (see page 114).
In contrast with this, we give a cut of our 8-inch gun, which most
nearly resembles it as a chambered gun (see page 114).
The reader’s attention is especially directed to the dissimilarity in
the distribution of the metal in the two guns. The want of uniform
thickness of metal in our 8-inch gun must be sufficient to convince any
one that, if the Russian gun be properly constructed, the principle of
ours must be radically wrong. That such is the case, indeed, I cannot
doubt, the Russian gun having undergone such a test as would have
destroyed six of ours. The gun has since been made two inches larger in
the bore, and even oval-bored, for firing shells, which should alone be
enough to destroy it; and yet with all this the gun remains perfect.
The gun which most nearly resembles this is our English carronade; and
that these guns have some important principle in their shape is proved
by their great durability under all trials; and I believe that the tests
to which the carronade has been subjected have been more severe than
that of any other piece in the British service.
There have been many shrewd conjectures as to the cause of this
durability; one of these was very pungent, viz., “the invention was not
by one of the cloth.” An examination of the drawing of the 68-pounder
carronade will enable the reader to perceive the great similarity
between this and the Russian gun before spoken of (see page 114).
[Illustration: 68-pound carronade.]
The manufacture of these guns was originally in the hands of the
inventors, and it is quite evident that they must have taken great pains
with the form of the gun, and also have taken special care that the
material of which it was constructed was of the very best quality.
There is too much reason to doubt the proficiency of military men in
the science of metallurgy; and the British system of depending solely on
their knowledge for the last half century, has no doubt proved an
obstacle to advancement in the science of gunnery.
[Illustration: Monck’s 56-pounder gun.]
The gun which ranks next is Monck’s 56-pounder. Although not a chambered
gun, it will be seen, from the diagram (see p. 117), to be an attempt
(if not a perfectly successful one) to obtain uniformity of thickness in
every part of the arc. The durability of these guns ranks as we have
placed them.
The next in rotation is the 8-inch or 68-pounder (see p. 114); which,
although not the original sized gun that was rifled for the Lancaster
shell, yet it was the one eventually used for that projectile up to the
end of its very brief career.
[Illustration: 10-inch or 86-pounder gun.]
The 10-inch gun of 95 cwt., delineated at page 117, will be seen to be
defective in its outlines when tested by the principles before laid
down, and the fact of more 10-inch guns bursting at Sebastopol than any
others (mortars only excepted), may be taken as exclusive evidence of
its imperfection.
The bursting of mortars is quite notorious, especially the 13-inch
mortars used for sea-service in the attack on Sweaborg. A slight
examination of the engraving of one will be sufficient to convince any
person that, if what has already been advanced on the form of guns can
lay claim to being scientific, then this is of all guns the most
unscientific that was ever manufactured. Its durability, too, like its
shape, is of a very low order.
[Illustration: 13-inch sea-service mortar.]
The 13-inch land mortar depicted below is a much more serviceable
production, because it contains much less metal.
[Illustration: 13-inch land-service mortar.]
Mortars will retain their place in spite of all improvements. Rifling is
inapplicable to them. Their principal utility consists in obtaining a
vertical fire; the shell being pitched to a great height, so as to fall
into places that cannot be assailed by a horizontal fire.
The late Joseph Manton has the merit of being the first modern inventor
of rifled cannon. His idea was, that if a motion on an axis parallel to
the horizon could be given to cannon balls, they would range farther and
with greater accuracy. As there exists great difficulty in causing the
rifling in a gun to act upon an iron ball, he constructed a cup of wood,
into which the ball was fitted, projections being made upon the wood to
fit into the groves of the rifle; the spinning motion thus being
communicated to the ball by its wooden adjunct. The result was twofold;
for the expansions of the wood during the explosion, filled the tube of
the gun tight, and effectually destroyed the windage. The government of
the day did offer him a premium of one farthing each; but “Joe”
over-reached himself, asking the sum of £30,000 down; this was refused,
and the patent was allowed to expire without the Government taking any
advantage of it, and experiments ceased to be made in this direction.
Rifled cannon have now, however, become a certainty. Mechanically
speaking, they are as easily to be produced as hand rifles. The general
application has, however, vast difficulties, which must be overcome
before their use can become general. Small arm projectiles suitable for
rifles must of necessity be made of ductile metal, and all the attempts
previously made, whether with brass or iron guns, are alike useless. The
mass in motion, even when of equal hardness with the gun (as in the case
of cast iron guns and cast iron shot), invariably destroys that in a
comparative state of rest; and the rifling is obliterated after a very
few discharges. In a brass gun the destruction is certainly not so
rapid, on account of the different nature of the metal; yet the
destruction of the gun for all useful purposes is equally effectual. It
is evident, then, that success cannot be obtained by using the present
materials in rifled cannon; and the question inevitably arises, what
better material can we use? Wrought iron shells have already been
thoroughly tried in the Lancaster oval gun, with a well-known result.
Great hopes were at one time entertained, that something suitable would
result from Mr. Bessemer’s discovery of the combustion of carbon, and
that an iron of sufficient ductility, yet without the usual hardness,
would be produced; but this, it appears, is still a myth.
Extent of range and accuracy of fire in gunnery will in future be of so
much importance in war, that it is not extravagant to assert, that in
contests between well-matched belligerents, the precious metals (if they
gave any advantage to the user) would be unhesitatingly used in
projectiles. But on the score of economy, science need not be impeded.
Gun-metal projectiles and cast steel cannon would work as effectually
together as lead and iron in small arms.
Some other mixtures less expensive might be produced (lead and copper in
certain proportions are very ductile), and at the same time sufficiently
strong to resist all tendency to squash; as the softer metals would
inevitably do. The more ductile metals are limited in their utility, by
the same law which limits the use of pure lead: that is, to given
weight, height of column, or velocity. Great doubt exists whether a
bullet made of gun metal, and of the same proportionate dimensions and
form as an Enfield bullet, but fitted for a ten-inch gun, would not, if
fired with the proportionate charge of powder (namely, seventeen
pounds), be as completely squashed, or driven in upon itself, as the
Enfield bullet if fired with the old Brown Bess charge of four drachms
and a half.
Considerable time and experience will be required to ascertain the
proportions of metallic mixture necessary to meet all contingencies;
this, however, is a matter of detail, and must extend over so large an
area, that it can be handled only by the government officials, with the
necessary “sinews” of experiment. Nevertheless it must be undertaken;
and the sooner it is done the better, for the prestige of that nation
which would lead the van of improvement in gunnery, and increase its
power of attack and defence beyond those of its rivals.
Rifled cannon is a generic term of endless application, presenting to
the mind modifications of projectiles in endless variety, ranging from
the “_light firebrand_” to the twice deadly rocket: not rockets of that
eccentric and erratic character by which Congreve made an undying name;
but real _bonâ fide_ rifle rockets, which shall hit the dead-lights in
the quarter-gallery of a frigate, carry away the halyards of your
enemies’ ensign (making him drop his colours at the first shot) or dash
the glass from the hand of the pilot. All such imaginary feats will yet
be accomplished; though the reader may smile at the idea. My experience
with rockets goes to justify me in asserting that rockets discharged
from a gun, under certain circumstances, can be as effectually
controlled, and kept to a direct course, as a bullet fired from a rifle.
The rocket, however, may be fired a much greater distance than we have
ever been able to project a bullet; because, in addition to the force
which projects it from the gun, its flight is maintained by the self
sustaining agency in the body of the rocket. Rockets require a much
smaller charge of powder to project them than that which is used for a
bullet; a rocket started by its own force, expends, in acquiring even an
approximation to its highest velocity, at least one-third of the force
with which it is charged; but when projected by a small charge of
gunpowder this force is saved, and the flight of the rocket is
afterwards sustained by the force with which it is charged.
Firing rockets from cannon can only be practised under certain
circumstances. The observations already made on the granulation of
gunpowder will have prepared the reader for this announcement. When
fired from a cannon under the old régime, the rocket was projected at
high velocity, and the case of the rocket was destroyed by the very
force which set it in motion. A rocket suitable for artillery should be
cast of gun metal, with a frame of considerable strength. In form it
should nearly approximate to an expansive bullet; but, instead of the
limited length of one and three quarters diameter; it should approach to
four diameters; two of which, at least, should be appropriated to the
cylinder behind the head.
The head is charged with composition more densely driven than is
customary in the ordinary rocket; the tubes in the cylinder are also
charged with a composition equally dense. The outer frame of the rocket
is cast with suitable projections to fit the grooves of the gun: the
spiral of these grooves is considerable, being one turn in every three
feet, in order to impart to the rocket an effectual spinning motion when
in a low state of velocity. The rocket properly constructed is then
placed in the rocket-gun, and fired in the usual way; but it is
essential that the gunpowder used should be of a suitable quality: its
combustion must be as slow as possible, a starting velocity of from 500
to 800 feet per second being sufficient to ensure the flight of the
self-sustaining projectile to the end of its range. This principle may
be extended from a light firebrand, as already stated, to that of a
rocket charged in the head with the most deadly and destructive
fulminate.
It may appear absurd to speak of fulminates being projected; since all
experiments show that fulminates, even when adulterated, will not stand
the concussion of a discharge, but invariably ignite in the gun, however
carefully placed or packed in the shell which contains them: for this
reason fulminates have never been successfully used. But if the
fulminate is placed in the head of a rocket, this objection may be
obviated. The gradual manner in which velocity is given to a rocket does
not subject it to violent displacement during its flight; neither need
the concussion in the gun be severe, owing to the nature of the
gunpowder used, which in its gradual expansion is analogous to steam:
thus the field for the application of fulminates is opened to an
unlimited extent.
My own experience on this subject has been limited to its application
for the saving of life from shipwreck, where the application of a line
to the rocket limits its range and velocity; but sufficient is left in a
rocket of an inch and a half diameter effectually to carry out a line of
a quarter of an inch diameter to a distance of 600 or 800 yards: that
is, more than double the distance obtained by either Manby’s apparatus
or the rockets now in use; which, lamentable to state, are quite
inadequate to the purposes for which they are intended.
Though the improvements in rifled cannon are at present only in their
infancy, they have nevertheless attained to an extraordinary degree of
perfection, verifying all our predictions to the letter.
A writer in the _Times_ makes the following statements in favour of Mr.
Whitworth’s improvements:--
“While some men of really inventive talent, and a great many charlatans,
have been permitted to waste the public money in trying vainly to
improve our artillery, it seems passing strange that it should not long
ago have been discovered how impossible it was to hope for successful
results in the direction in which they were working. It was clear that
while increased range and precision of firing were wanted, it was nearly
as important to bring the charges of ammunition and the weight of metal
in guns into more manageable proportions to each other, and to the
facilities for transit on active service. No sensible man can have
witnessed the frightful damage done to the efficiency of our army in the
Crimea by the exigencies of the siege-train during the winter of 1854-5
without being impressed with this conviction. The principle of the rifle
offered an obvious suggestion for the proper means of working out the
foregoing problem; but then for artillery, rifling by grooves would not
do without the use of a pliant metal in the projectile, and the cost of
lead rendered its application to that purpose impracticable. It was
necessary, therefore, to alter the existing mode of rifling, and to
modify the bore of the cannon, so that an iron projectile could be
discharged from it, rotating on its own axis in the line of flight. This
result once secured, it is obvious that a field-piece or gun of position
would become a rifle on a large scale, and that the same immense
increase of range and of penetration which had been realised by the
smaller weapon as compared with Brown Bess, would be placed at the
command of the artillery service. It is consolatory, after a series of
failures worthy even of Brunel in launching the _Leviathan_, that the
country has at last the well-grounded hope of an improvement by which
our ordnance may be placed on a proper footing. In pursuing those
careful experiments which he undertook for the Government, principally
to improve the rifle, Mr. Whitworth, the eminent machinist, adopted a
polygonal spiral bore of a uniform pitch, but more rapid than could be
attained by grooves. This bore has enabled him to surpass immensely the
range and penetration of the Enfield rifle; but even these advantages,
important as they are, scarcely surpass those which it places within the
reach of our artillery service. The strain of the projectile being
distributed evenly over every side of the polygon, iron can be
substituted for lead in the projectile, and this simple but beautiful
mechanical appliance at once becomes available for cannon.”
The powerful aid of the _Times_ is “almost success;” though in this
instance it has signally failed, the boasted accuracy there spoken of
not having been yet obtained. This has no doubt arisen in part from the
fact that Mr. Whitworth’s great mechanical knowledge would not suffice
to make him _au fait_ at the compound science of gunnery. His “polygonal
spiral bore of uniform pitch, more rapid than could be obtained by
grooves,” is after all only an experimental gun, not sufficiently
developed as yet for practical utility. Still, the writer already
alluded to has favoured us with the following remarks in the _Times_:
“Moreover, Mr. Whitworth has discovered in the course of his
experiments, that according to the quickness of the turn in the polygon
is the length of the projectile that may be fired; so that 24 lb. and
48 lb. shot have been sent to extraordinary ranges with half the usual
charge of powder, from an ordinary 12-pounder howitzer. Here, then, is
at once the solution of the whole question which has troubled the brains
of so many inventors, real or pretended, for years. The artilleryman at
one stride resumes the relative position to the soldier of the line
which the Enfield rifle had so perilously deprived him of, and this
mechanical country, after finding herself on the level of France,
Russia, and other European States, is once more, as during the
Peninsular campaigns, enabled to assert her natural superiority in the
manufacture of cannon. We trust that no petty jealousies on the part of
narrow-minded officials will be allowed to interfere with the course of
Mr. Whitworth’s experiments, and that the encouragement which he is now
receiving from the Minister at War and the Commander-in-Chief will
enable him, at no remote date, to realise for the benefit of the army
and the nation that revolution in gunnery which the results already
obtained by him promise.”
Report says that 25,000_l._ is the amount of encouragement Mr. Whitworth
has received from the Minister of War and the Commander-in-Chief; an
adequate sum with which to conduct such an experiment, but not
sufficient to insure success.
Of the success of Mr. Whitworth’s polygonal projectile, on a large
scale, none need speculate, for the principle is self-destructive.
Lancaster’s oval shell, oscillated in its flight, took a flight so
extraordinary, on account of the resistance of the atmosphere on the
protuberances of the oval, that the principle may be regarded as fully
established that enlarged projectiles must be smooth and free from
projections that “saw the air,” otherwise range and accuracy of fire
will be sacrificed. The principle of Mr. Whitworth’s polygonal bore is
fully discussed in its proper place, and will here receive only a
passing notice.
To Mr. W. G. Armstrong, of Newcastle-upon-Tyne, much more credit is due
than can be claimed for Mr. Whitworth. Long before the paid efforts of
Mr. Whitworth, Mr. Armstrong had made the subject of rifled cannon a
special study, and the success of his investigations has been such as to
couple his name with those of the earliest inventors of effectual rifled
cannon. Mr. Armstrong may also lay claim to being an originator of
wrought steel cannon; though here his name stands second as an inventor,
for to Mr. Krupp is due the honour of first introducing cast steel
cannon to the notice of our Government.
Mr. Armstrong tells his own tale so well in the columns of the _Times_
that we cannot do better than quote it:--
“In the latter part of 1854, I submitted to the Duke of Newcastle, then
Minister at War, a proposal for a gun which I anticipated would possess
great superiority over the common forms of light artillery, and I
undertook, with his Grace’s authority, to construct a field-piece in
conformity with the plan I had suggested. The gun was accordingly soon
afterwards made, and has since, during a period of nearly two years,
been the subject of numerous experiments, partly upon the ordnance
firing-ground at Shoeburyness; but principally under my own direction in
this neighbourhood.
“I have hitherto avoided publicity in reference to these experiments,
but, as matured results of much interest and importance have now been
arrived at, and as other names are already before the public in
connection with gun experiments made during the same period, I feel that
I may now, without impropriety, give some information on the subject.
“With a view to strength and durability, the gun is composed internally
of steel and externally of wrought iron, applied in a twisted or spiral
form, as in a musket or fowling-piece. The bore is nearly two inches in
diameter, and is rifled. The projectile is a pointed cylinder 6-1/2
inches long, and its weight is 5 lb. It is made of cast iron, coated
with lead, and is fired from the gun with a charge of 10 ounces of
powder; it contains a small cavity in the centre, and may be used either
as a shot or a shell. When applied as a shell, the cavity is filled with
powder, and a detonating fuse is inserted in front, so as to fire the
powder in the centre on striking an object. When used as a shot, the
powder is omitted, and an iron point, which favours penetration, is
substituted for the fuse. The gun is constructed to load at the breech,
the object being not only to obviate the disadvantages of sponging and
loading from the front, but also to allow the projectile to be larger in
diameter than would enter at the muzzle, and thus to insure its taking
the impress of the grooves and completely filling the bore. The piece
weighs 5 cwt., and is mounted upon a carriage which bears a general
resemblance to that of an ordinary 6-pounder field gun, but which
embraces a pivot frame and recoil slide. A screw is also applied, not
only for elevating and depressing the gun, but also for moving it
horizontally, by which means great delicacy of aim is effected. The
recoil slide has an upward inclination, which enables the gun, after
running back, to recover its position by gravity; and its use is to
relieve the pivot-frame and adjusting screws from injurious concussion.
“I shall now give some particulars of the experiments recently made with
this gun on the coast of Northumberland, near the village of Whitley,
under the official inspection of Colonel Wilmot.
“Fourteen shots were in the first instance fired from a distance of
1,500 yards at a timber butt, 5 ft. wide 7-1/2 ft. high. Six of these
were expended in finding the elevation proper for the distance, but
after that was determined every succeeding shot hit the object without
previous graze. The final elevation of the gun was 4 deg. 26 min., and
the mean lateral distance of the shot-marks from a vertical line through
the centre of the butt was only 11-1/2 in.
“Persons who are conversant with artillery practice will be able to
appreciate the accuracy of this firing; but, for the information of
those who are unacquainted with the subject, I may state that the
ordinary 6-pounder field-piece, which in point of weight forms the
nearest approach to the present gun, is perfectly useless at a distance
of 1,500 yards, and is very uncertain even at 1,000 yards. It is only,
therefore, with heavy artillery that a comparison can be drawn; and it
will be sufficient to state that in tabulating the practice made with
such ordnance the deflections are invariably recorded in yards, whereas
with this rifled gun they can only be properly given in inches.
“With respect to penetration, the following particulars will be regarded
as equally remarkable, considering the small weight of the shot and the
length of the range. The butt was 3 ft. thick, and was composed of six
layers of rock elm bolted together, so as to form a solid block. One
shot passed entirely through; another struck near the edge and glanced;
and the remaining six penetrated within a few inches of the opposite
side.
“Shell firing was next tried at a distance of 1,500 yards; the gun being
fired at the same elevation and with the same charge as in the previous
practice at the butt.
“In this case two targets were erected, one behind the other, so as to
appear as one object when viewed from the gun, and a space of 30 feet
was left between them. The front target was intended to exhibit the
perforations of the shell before bursting, and the back one to show the
effect of the fragments resulting from explosion.
“After some preliminary experiments twenty-two shells were fired at the
front target, and of these only one missed the object of aim. The
following are the particulars:--Seventeen hit the first target direct,
and burst behind it, the fragments penetrating the second one; three
grazed and burst immediately in front of the first target, and
perforated both with the pieces; one hit the bottom of the first target
and exploded in the ground, and the remaining one missed entirely and
burst on some rocks nearly on line beyond. A strong side wind was
blowing at the time, and accounted for the deviation of this single
shell.
“Four shells and three shots were then fired at an elevation of 6
degrees, from a distance of 2,000, or, more accurately, 1,964 yards. All
these struck within the breadth of the target; but the elevation being
scarcely sufficient, they all fell a little short, except one shell,
which, ranging somewhat further than the others, hit the target and
burst as usual.
“The results of this shell-firing were as follows:--The front target
contained 51 holes, and the back one 164, while the ground between and
adjacent to the targets exhibited about 70 perforations by fragments of
shells, the greater portion of which were afterwards recovered by
digging.
“With respect to ranges exceeding 2,000 yards, I may state that on
previous occasions the gun had been tried up to 3,000 yards--a distance
which was reached with an elevation of 11 deg., and the usual charge of
10 ounces of powder, or 1-8th the weight of the projectile. By
augmenting the charge the range is increased, but the accuracy is
impaired; and I therefore adhere to the 10-ounce charge, which gives
ample penetration, as the experiments at the butt will testify. I may
also observe that the ranges obtained with this charge bear a favourable
comparison with those of the heaviest round-shot guns fired with a much
larger proportion of powder.
“It is a curious fact, and one which greatly increases the efficiency of
the shells, that owing to the bursting charge requiring a minute space
of time to mature its ignition after the firing of the fuse by impact,
the shell is enabled to travel four or five feet after striking an
object before disruption takes place. Hence, therefore, it acts as a
shot before it bursts as a shell. When it perforates a target the
explosion may be seen to take place at a few feet beyond, and when it
grazes it has time to rise, and may be observed to burst after clearing
the ground. If, therefore, it were fired against a ship, it would first
penetrate the side in its entirety, and then, bursting, traverse the
deck in fragments; or if directed against troops, it would pierce the
front line as a bullet, and operate like grape-shot beyond. The shells
explode with equal certainty whether the first substance struck be hard
or soft; and, in fact, they even burst on the surface of water, provided
the elevation of the gun be not too great. The bursting charge is very
small, but it suffices to break the shell into about 30 pieces, which
pursue their forward course without too much dispersion.
“It is impossible to contemplate the results obtained with this gun
without being impressed with the important part it is calculated to
perform in warfare. Opposed to any ordinary field-piece, it would be
like the Greener rifle against the old musket; and no gun could be
worked at an embrasure if a fire of shells were directed against it by
one of these rifled pieces placed within the distance of a mile. In
naval operations, also, guns of this description, but of larger size,
might apparently be applied with great effect--more especially as a
system of breech loading, combined with a self-recovering recoil action,
would be peculiarly advantageous in firing from portholes. Even light
5-pounders, sending their shells from great distances through the sides
of a ship and sweeping the decks with fragments of lead and iron, would
produce very destructive effects; and a small swift steamer carrying a
few such guns might prove a very troublesome opponent to a large ship of
war. But if the dimensions of the gun were increased so as to adapt it
for shells of 20 lb. or 30 lb., still more terrible injury could be
inflicted at greater distances; and the ponderous artillery now used at
sea would be of little service when opposed to the accurate and
long-range firing of such rifled shell-guns.”
Since the publication of these remarks, rifled artillery of Mr.
Armstrong’s production has, we believe, been extensively tried. The
results of these trials have been most extraordinary; and the principle
is, we believe, identical with the expansive principle bearing my
cognomen: an extension of the principle of the Greener and Enfield
rifle, hereafter to be described. I have had the honour of being
consulted both by English and foreign authorities, and I have assisted
in constructing rifled artillery for several years; and the experience
thus obtained justifies me in making known to the world some of my
observations on this subject.
Rifled cannon with elongated projectiles, similar in shape and principle
to the Greenerian bullet, give, with charges inferior to those of the
old régime and calibre, more than double the range, with ten times
greater accuracy.
Now, either of these points, if gained, would be most important
improvements, and when combined would produce the most extraordinary
results. But this is not all: a great diminution in the weight of the
gun might also be effected; and these advantages may be still further
extended when we have had time to increase our knowledge of the valuable
materials with which we are only just now becoming acquainted.
The following table will show the advantages to be gained both in length
and accuracy of range.
Before reverting to the table, it may be necessary to remind the reader
that the great reduction in the weight of guns arises from the adoption
of the elongated projectile. For example: the diameter of the
_elongated_ projectile for an “18-pounder” is much less than the
diameter of the gun for the _spherical_ 18-pounder; thus allowing the
thickness of metal to be equal in both guns. The gun for the elongated
projectile may be greatly reduced in weight without at all diminishing
its strength, simply on account of the great diminution in the diameter
of the arc.
There is another important fact, which Mr. Whitworth, with all his
boasting, has carefully concealed: viz., that a much greater pressure is
exerted upon the square inch in the lesser than in the larger diameter
of bore; and to conceal this fact, whilst claiming merit for a bullet of
50-gauge exceeding in range one of 25-gauge, the charge of gunpowder
being alike in both cases, appears very like deception. Any engineer
will tell us that the pressure in the lesser is twice as great as in the
larger bore; and this explains why greater velocity is given to the
projectile.
With these explanations the reader will be better prepared to weigh
carefully my observations. My task would, doubtless, have been rendered
more easy, if a clear elucidation of the principles of the expansive
bullet could have been given thus early in the work; but it is thought
better to do this in its proper place. I will only add here, that
although two bullets, one elongated, the other spherical, and of equal
diameter, meet with the same amount of atmospheric resistance, yet the
one containing twice as much matter as the other retains its medium
velocity nearly double the distance. With these explanatory remarks I
give the following table:--
------------------+-------------+-------+--------------+----------
|Present Range|Present|Reduced Weight|Range when
|of Guns. |Weight.|when Rifled. |Rifled.
------------------+-------------+-------+--------------+----------
6-pndr. | 1,500 yds. | 17 | 12 cwts. |3,000 yds.
9-pndr. | 1,600 „ | 26 | 18 „ |4,000 „
12-pndr. | 1,700 „ | 34 | 22 „ |4,500 „
18-pndr. | 1,780 „ | 42 | 29 „ |5,000 „
24-pndr. | 1,850 „ | 50 | 34 „ |5,500 „
32-pndr. | 2,000 „ | 63 | 42 „ |6,000 „
48-pndr. | 2,500 „ | 70 | 45 „ |6,500 „
56-pndr. | 5,000 „ | 85 | 60 „ |8,000 „
68-pndr. or 8-in. | 4,500 „ | 85 | 60 „ |8,000 „
86-pndr. or 10-in.| 4,700 „ | 95 | 65 „ |9,000 „
------------------+-------------+-------+--------------+----------
The reader must understand that all the guns given in this table were
not rifled, and that they have not all been subjected to trial. The 6,
12, 18, 24, and 48-pounders have been tried, with the results given
above; but the heavier guns have not as yet been tested: the ranges and
weights given in the table have, however, been derived from the results
yielded in the trial of the lesser guns, and may be safely relied on as
scientific data; being, in truth, rather under than over the mark.
All experiments clearly establish one very important principle, long
known to those acquainted with the science of projectiles, viz., “That
the heavier the projectile, the less the deflection.” Thus it is quite
possible that the longest ranges may ultimately be obtained without any
perceptible deflection. And when we observe that the deflection of an
ordinary 32-shot in a range of 2,000 yards, is 50 feet, and in 2,500
yards, 80 feet, whilst the elongated shot, at a much greater distance,
is not deflected half as many inches, I think we may fairly say that our
knowledge of gunnery is yet in its infancy. Fulminating powder may be
used as an auxiliary in shells for various important purposes; such, for
instance, as destroying an entire fleet; and it is clearly within the
range of possibility that by its agency the largest ship may be
destroyed by a single shot. The accuracy of rifled cannon renders it an
easy task to strike a plank only one inch above the water line, and the
penetration of an elongated gun-metal or lead-alloyed shell would enable
us to reach the innermost parts of the magazine: for it is scarcely
possible to produce even an iron casing which shall resist the power of
such projectiles. It is possible, therefore, that we may see the noblest
fleet destroyed in a few minutes by the agency of such projectiles.
I will endeavour to give an outline of the method by which this may be
effected. A long rifled cannon, constructed for an elongated gun-metal
shell; of from fifty-six to eighty-six pounds, and with an extreme range
of from 6,000 to 7,000 yards, may be considered to be a suitable
instrument. This shell should be charged in the head with a given
quantity of the fulminate, such as would be most calculated to prevent
the tendency to explode from the concussion produced by the discharge of
the gun. It will be necessary to place the fulminate in thin layers
between sheets of prepared caoutchouc, or some other preparation of
India-rubber; having thus arranged the fulminate in the head of the
shell and secured it there, the usual method of filling the remainder is
resorted to, and the aperture is securely screwed up: fuses not being
necessary in this arrangement.
The difficulty in using this shell is to prevent its explosion when the
gun is discharged; and to obviate this all our engineering skill is
required. Time and experience will show that, by a modification of the
propelling agent, the shell may be started from a rifled cannon at a
very low velocity; the velocity being increased like that of the rocket.
This is to be done by modifying the arrangement of the gunpowder so as
to ensure the shell acquiring its greatest velocity as it leaves the
muzzle of the cannon. The result of this has been already shown. On the
shell striking any object, such as the ship’s side, the metal of the
shell is driven in upon itself, and an explosion of the fulminate
follows as a natural consequence. Experiment has proved that shells
exploding as they strike the ship’s sides, produce very little damage
beyond making a hole in the ship the size of the shell. This, no doubt,
arises from the short space of time occupied by the shell in passing
through the side of the ship; all its force being exerted in the
interior instead of on the sides of the vessel. All shells of the nature
alluded to would, at certain distances, take such a line of flight as to
ensure them dipping towards the centre of gravity, and thus exploding
the magazines, however deep below the water-line; and when we consider
the destructive effects of fulminates, we think it quite within the
range of probability that they might produce all the effects we have
spoken of.
There are many agents equally powerful to be introduced into destructive
warfare; and with the advantages to be derived from improvements in
rifled shells, which the ingenuity of the present race will certainly
effect, he would be a rash man who would set any limits to the
advancement of projectile science. The great difficulty in the use of
fulminates will be surmounted if these suggestions can be carried out;
and experiment is all that will then be necessary to establish the line
of proceeding. To effect this is the province of the Government of the
country; to wait for it to be perfected by individual skill and
enterprise would be unjust to science, and injurious to the best
interests of the nation. The needful expenditure can only be borne by
the nation, and should be entered upon, in order to effect improvement
in projectiles, with the view of maintaining our land and marine
artillery at the highest point of efficiency.
There is one question of great importance to inventors, and to which I
have paid much attention, namely, the obtaining a spiral motion in a
projectile which has been fired from a smooth bored gun. All we have
witnessed goes far to prove that the attainment of this is impossible,
in consequence of a principle not hitherto investigated by inventors. If
the course of a projectile is changed from the straight to the spiral,
it can only be done at the expense of range; and that for the following
reasons: first, the force which is necessary to induce this spiral
movement must be exerted at the expense of the force which propels it
forward; secondly, when this spiral movement is acquired, it is so much
in excess of the direct movement, that after advancing a certain
distance it falls to the ground. A very simple experiment will prove
this. Take an ordinary tin tube, cut a bullet of an elongated
form--cylindro-conical if wished--having grooves from the point
backwards, with the degree of spiral necessary to effect the object in
view. Let the bullet be made of cork or light wood, such as can be
projected by a blast from the mouth, and the result will be that the
projectile will go one-half the distance before the friction of the
atmosphere produces a motion on its axis parallel to its line of
flight; from this point it gradually loses its velocity in a forward
direction, it spins until its force is expended, and then falls
vertically to the ground. To find the sequel, try the same experiment
without grooving, and the range, with the same force, will be found to
be double. Some years ago I witnessed such a trial with a 32-pounder;
and, to the astonishment of all present, the bullet rose above the
horizontal line, and then fell to the ground, like the cork bullet of
which we have already spoken.
The endeavour to produce breech-loading cannon is an effort to obtain
uncalled-for and superfluous facility in gunnery; and if a perfect
breech-loading cannon could possibly be produced, what would it avail?
What superior property could it possess over the solid gun? It could not
be safety; for when we consider the very limited number of explosions by
which the very best guns are destroyed, it can scarcely be possible for
a gun composed of many parts to endure the intense vibrations to which
large cannon are subjected. The regular distribution of vibrations in
the metal of the gun is the great point to be attended to in the
construction of artillery; so that vibrations may not be incorrectly
induced by malformation, or by an excess or deficiency of metal at any
particular point; for where the waves of vibration are checked by an
unequal distribution of metal, or other causes, there the weak point in
a gun is always found, as all fractured guns clearly demonstrate. An
intimate acquaintance with the metallurgy of cannon, enables me to give
an almost unerring opinion as to the causes leading to the fracture.
Most undoubtedly, vibration, if judiciously distributed, is the soul of
endurance; but if injudiciously distributed is certain to result in the
destruction of the cannon. In structures composed necessarily of many
joints, obstruction to the waves of vibration must occur; the different
parts do not expand and vibrate equally; a kind of revulsion is induced;
part repels part, and destruction ensues as a natural consequence. Under
no circumstances, therefore, can a breech-loader be as safe as a solid
gun.
The facility with which breech-loaders can be charged is generally
trumpeted forth to the world as an advantage of vital importance; but
let us carefully examine this point and see if it has not been
exaggerated--whether, in fact, a solid gun cannot be charged and
discharged as rapidly as a breech-loader.
In the first place, all guns recoil; this necessitates the relaying of
the gun after every discharge, in order to obtain accuracy of aim; and
if facility of loading is to be obtained at the expense of aim, it can
scarcely be called an advantage. Aim consumes more time than loading. A
six-pounder may be loaded and fired six times in the first minute; but
it would be impossible to do this and re-lay the gun after each shot.
Where then is the advantage of firing six shots per minute if you cannot
hit six objects? And if breech-loaders could be fired _sixty_ times per
minute, what would they avail if aim was wanting? The raising or
depressing of the breech of a gun by means of the elevating screw;
slewing to the right or left, spunging the gun, and ramming home the
powder and shot, all consume time; hence we think that quickness of
loading is worthless.
Breech-loading cannon cannot be constructed for bullets of larger
diameter than that of the rifle bore, without a ductile bullet be used;
for, as is usual in breech-loading small-arms, the bullet rifles itself
as it is forced up the grooves. The projectiles for rifled cannon have
hitherto been cast with corresponding grooves and lands to fit the
internal form of the cannon. A compound shot, composed of iron, and
covered externally with ductile metal, has been tried in a few
instances; but, unfortunately, the difficulty of combining two metals so
dissimilar as iron and lead has been found so great as invariably to end
in a failure; therefore no prospect exists of bringing into play this,
the best point existing in breech-loading arms.
Lastly, the tendency of all guns to absorb the heat, developed during
explosion, puts a limit to all extreme rapidity of fire; even if this
was not already limited by the more essential point of taking aim. At
Sweaborg it was found necessary to allow an interval of five minutes
between each discharge of a mortar, and yet the whole of them burst
after an average of 120 shots. Time and ingenuity spent in planning and
constructing breech-loading cannon will always end in disappointment and
failure. Many are the plans extant, evincing great skill, perseverance,
and everything needful in point of mechanical experience, but betraying
a total ignorance of the metallurgic science and of practical results
from the use of the engine. The study of these points will save money,
time, and what is of more value, brain-work, which might be better
employed. Striving to produce perfect breech-loading cannon is like
striving to square the circle.