ARTILLERY.
Arcualia, from “arcus, a bow,” appears to have been the original name,
and included all sorts of “missiles,” as well as the engines by which
they were propelled. The sling, still in common use by the Arabs on the
banks of the upper Euphrates, being most probably the first kind of
artillery, and the bow and arrow a succeeding stage of improvement.
Artillery, now in the general acceptance of the term, includes all and
every description of gun, of greater power and dimensions than muskets
and other shoulder guns.
Modern civilization, with its giant strides of improvement, has rejected
the cumbrous and unsightly complication of springs, levers and wheels;
and given to us, in their stead, the light and handsome six-pounder
cannon; which is so easy of transit that it can accomplish the most
complex and difficult movements, while the horses are at their fullest
gallop. A single minute now suffices to stop when at the greatest speed,
unlimber, load, fire a couple of rounds, and remount; the gun is
speedily at a distance--while the eye can scarcely follow, or the mind
imagine, the destruction that must follow when the “deep-tongued gun”
is fired in attack.
I shall now proceed to notice the comparative effects of guns of various
calibre and power, and attempt to convey to the reader a distinct idea
of their respective defects and advantages. The artillery of England
comprises an immense variety of weapons of war, suited for various
purposes and situations, as experience has dictated, or necessity
required. The present state of our artillery requires _an advance to the
front_, to be in a line with the march of science, as regards the
knowledge of gunpowder and projectiles; I may, therefore, be permitted
to animadvert on what appears to me to need improvement.
The profession may think it presumptuous in me to offer a suggestion or
give an opinion; for it too frequently happens that individuals, who
have employed their whole time and study on one especial subject, think
they alone can understand it, and consider any opposition to their
opinions, or any doubt of the soundness of their conclusions, little
short of a positive offence.
Having given considerable attention to the subject, I would now beg to
offer some remarks on the Government arrangements of gunnery, which are
not yet so perfect as they might be.
The authorities of the Ordnance Department are, I am sorry to state, too
remiss in considering, and too unwilling to avail themselves of valuable
improvements and discoveries; clinging too much to prejudice in favour
of whatever has been heretofore in use. To such an extent is this habit
carried, that many improvements become familiar to half the kingdom,
aye, and are adopted by other countries, before our guides take
advantage of them: for truly talent and ingenuity are but scantily
patronized by them. My wish is to aid in sweeping away the cobwebs which
still hang on the science of great gunnery; and to push the spur of
conviction deep, that instead of Britain following, she may, in a time
of peace, lead the way in improvements; so that whenever war returns,
she may not be unprepared to wage it on equal terms.
I have in this chapter endeavoured to divest the subject of all
extraneous matter, and impart as much information as will enable the
reader to form an opinion for himself, and understand something of a
science hitherto considered abstract, and which is, no doubt, abstruse.
This I have sought to effect in plain language, avoiding, wherever it
was possible, all technicalities.
The guns of the British nation may be divided into four classes--Park,
or Field artillery, Siege guns, or battering train, garrison guns, and
marine artillery. The numbers of different descriptions of rates, or
weight of guns, vary in all the different classes of the service. There
are light, medium, and heavy six-pounders; long and short twenty-four
pounders; and two or more weights in all the varieties, even up to the
ten-inch gun and thirteen-inch mortar. We have iron ordnance and brass,
for long and short ranges, for small or great velocity. The rate,
weight, length, charges, point blank, extreme range, &c., of iron guns,
will be found in the annexed table, by which will be seen, at a glance,
the various matters referred to.
IRON ORDNANCE.
---------+-------+-------+------------+------+-------+----------
Nature | | | Charge |Point |Extreme|
of |Weight.|Length.| of |Blank |at | Windage
Gun. | | | Powder. |Range.|5 deg. |decreased.
---------+-------+-------+------------+------+-------+----------
Pounders.| cwts. |ft. in.|lbs. ozs. |yards.| yards.|
32 | 63 | 9 7 | 10 10-1/2| 380 | 1950 | --
32 | 56 | 9 6 | 10 10-1/2| 380 | 1950 | --
32 | 48 | 8 0 | 8 0 | 330 | 1740 | --
32 | 40 | 7 6 | 6 0 | 340 | 1700 | ·06
32 | 32 | 6 6 | 5 0 | 330 | 1640 | ·11
32 | 25 | 6 0 | 4 0 | 225 | 1500 | ·11
32 | 25 | 5 4 | 4 0 | 225 | 1500 | ·11
24 | 50 | 9 6 | 8 0 | 360 | 1850 | --
24 | 48 | 9 0 | 8 0 | 360 | 1850 | --
24 | 40 | 7 6 | 8 0 | 340 | 1800 | --
24 | 33 | 6 6 | 6 0 | 260 | 1560 | --
18 | 42 | 9 0 | 6 0 | 360 | 1780 | --
18 | 38 | 8 0 | 6 0 | 340 | 1730 | --
12 | 34 | 9 0 | 4 0 | 360 | 1700 | --
12 | 29 | 7 6 | 4 0 | 340 | 1650 | --
9 | 26 | 7 6 | 3 0 | 330 | 1600 | --
6 | 17 | 6 0 | 2 0 | 320 | 1520 | --
Carronades. | | | | |
68 | 36 | 5 4 | 5 10-1/2| 270 | 1420 | --
42 | 22 | 4 6 | 3 8 | 240 | 1350 | --
32 | 17 | 4 0 | 2 10-1/2| 235 | 1260 | --
24 | 13 | 3 9 | 2 0 | 225 | 1150 | --
18 | 10 | 3 4 | 1 8 | 220 | 1100 | --
12 | 6 | 2 8 | 1 0 | 205 | 1000 | --
---------+-------+-------+------------+------+-------+----------
Brass guns are invariably lighter, and considered less likely to burst.
Gun metal, technically so called, is a compound of copper and tin, in
the proportion of five, eight, and ten pounds of the latter to 100
pounds of the former. The peculiar property of the tin is to give
hardness and solidity to the mass. The greater proportions are used
principally for mortars, as they require a greater degree of hardness
than other guns. A peculiar property attaches to the using of brass
guns. If a considerable number of rounds be fired in rapid succession,
the bore of the gun becomes to a certain extent elliptical. This
peculiarity arises entirely from the extreme windage allowed by the
present established rules of British gunnery; and is produced by the
tendency of the shot, when propelled by the explosive force, to strike
upwards from the breech, and then rebound downwards, and so on till it
reaches the muzzle. Iron guns are not liable to this (although the same
cause exists) from the unductile nature of the cast iron.
Brass guns are, after certain use, recast: this is done solid, with the
cascable of the gun downwards, to give a greater density to the metal at
the breech. The boring and turning are performed simultaneously by a
very simple arrangement. At the siege of Badajos, the firing continued
for 104 hours, and the number of rounds that each gun fired averaged
1,249; and at the siege of Sebastian, the quantity fired by each gun was
about 350 rounds, in 15-1/2 hours. These guns being of iron, none of
them were rendered unserviceable; though three times the number of brass
guns would not have been equal to such long and rapid firing. All brass
guns are bouched with a bolt of copper at the vent, on the same
principle as flint guns for sporting were formerly with gold or platina;
copper withstanding the rapid escape of the flame better than the
gun-metal. The charges, ranges, &c., are as follows:--
EXTREME AND POINT BLANK RANGE OF BRASS ORDNANCE, CHARGE, &C.
-----------------+-------+------+-------+------+----------------------
|Charge.|Point |Extreme|Eleva-|
---- | |Blank | Range.| tion.| ----
| |Range.| | |
-----------------+-------+------+-------+------+----------------------
|lb. oz.|yards.| yards.| deg. |
Medium 12-pounder| 4 0 | 300 | 1,200 | 3 |}
Light 12-pounder | 4 0 | 200 | 1,000 | 3 |}
9-pounder | 3 0 | 300 | 1,200 | 3 |}With round solid
Long 6-pounder | 2 0 | 300 | 1,200 | 3 |}Shot.
Light 6-pounder | 2 0 | 200 | 1,000 | 3 |}
Heavy 3-pounder | 1 0 | 200 | 1,000 | 3 |}
24-pounder | | | | | }
howitzer | 2 8 | 250 | 950 | 3-1/2| }
12-pounder | | | | | }With common Shells.
howitzer | 1 4 | 200 | 950 | 3-3/4| }When Shot is fired,
Heavy 5-1/2-inch | | | | | }they increase the
howitzer | 2 0 | 250 | 1,750 | 12 | }elevation 1/2 a deg.
Light 5-1/2-inch | | | | | }
howitzer | 2 0 | 100 | 1,350 | 2 | }
-----------------+-------+------+-------+------+----------------------
The twelve, ten, and eight-inch guns, almost form a class of themselves,
known as the “Paixhan Gun.” They are intended for throwing both hollow
and solid shot. The larger are the description of ordnance with which we
at present arm our steam frigates.
These are unquestionably part of the many doubtful descriptions of
artillery which have been adopted of late years, with a view to
_fracture_ more than to secure a range of projectile. They are enormous
machines, as will be seen on reference to their weights, as given in the
following table; and their splintering powers are certainly very
extensive indeed. But their range is contemptibly small, if we take into
consideration their great weight. The effect of the explosion of the
charge of one of these guns must be sensibly felt even by the strongest
built steamer in the world. They are used with traversing beds. The gun
carriage, when recoiling, in a backward direction, being driven up an
inclined railway, with from 3° to 4° of elevation, from the cascable of
the gun. This greatly tends to lessen the distance which the gun would
be driven back, and facilitates the running out of the piece to the
point of discharge. The woodcut gives a representation of the traversing
beds; and the following table displays the ranges, &c., of this class of
heavy artillery.
[Illustration]
RANGE AND ELEVATION, &C., OF 12, 10, AND 8-INCH GUNS, AT POINT BLANK AND
EXTREME, AND 10 AND 8-INCH HOWITZERS.
-------------------+---------+--------+---------+------+-------+------
| | | Charge |Point |Extreme|Eleva-
Nature of Ordnance.| Length. | Weight.| Powder. |Blank | Range.|tion.
| | | |Range.| |
-------------------+---------+--------+---------+------+-------+------
|ft. in. |cwt. qr.|lbs. ozs.|yards.|yards. |deg.
12-inch gun, with }| | | | | |
hollow shot, }| 8 4 | 90 3 | 12 0 | 240 | 1,550 | 6
weight 112 lbs. }| | | | | |
10-inch, with } | | | | | |
ditto, weight 86 } | 7 6 | 57 3 | 7 0 | 210 | 1,500 | 6
lbs. } | | | | | |
Ditto | 8 4 | 62 1 | 8 0 | 250 | 1,400 | 5
Ditto | 9 4 | 84 0 | 12 0 | 325 | 1,700 | 5
8-inch gun, with }| | | | | |
hollow shot, 48 }| 6 8-1/2| 50 0 | 7 0 | 210 | 1,300 | 5
lbs. }| | | | | |
8-inch ditto, } | | | | | |
solid shot, 68 } | 8 6 | 60 0 | 9 7 | 340 | 1,500 | 5
lbs. } | | | | | |
Ditto | 9 0 | 65 0 | 10 0 | 300 | 3,250 |15
Ditto, hollow shot | 9 0 | 65 0 | 12 0 | 370 | 2,920 |15
10-inch iron | | | | | |
howitzers | 5 0 | 40 0 | 7 0 |2 deg.| 2,078 |12
| | | | 600 | |
8-inch ditto | 4 0 | 21 0 | 4 0 |3 deg.| 1,725 |12
| | | | 730 | |
-------------------+---------+--------+---------+------+-------+------
[2] Length of time occupied in flight, 14 seconds, and 15-1/4
seconds.
Mortars are intended for three purposes; firstly, to bombard a town, or
injure the defenders’ artillery; secondly, to fire or overthrow the
works, and to spread havoc and slaughter among the troops; thirdly, to
break through the vaulted roofs of barracks and magazines which are not
bomb-proof, or, in other terms, are not strong enough to resist the
fire.
They consist, as will be seen, of five descriptions, but the 10-inch is
considered, on the score of economy, as equal to all useful purposes.
The French have, at various times, constructed mortars of enormously
large dimensions, but certainly with no useful result. The monster
mortar, used at the siege of Antwerp, fired only ten or twelve shots,
and with comparatively little effect. It burst some time after, while
under a course of experiment, with a considerably less charge than it
had formerly withstood; thus affording one very conclusive and
illustrative fact in the theory of vibrations in metals: for there can
be no question but that the shell, from the smallness of the charge, was
too long detained in the mortar; the waves of vibration caused by the
explosive force moving so rapidly through the mass that the metal at
last lost its cohesive nature from their very rapid succession.
It will be perceived, on reference to the adjoining tables, that ranges
are obtained by the modifications of charges.
ENGLISH MORTAR PRACTICE.[3]
[3] Artillerist’s Manual.
--------------------------------++--------------------------------+
13-INCH IRON. || 10-INCH IRON. |
Weight, 16 cwts. || 16 cwts. 2 qrs. |
Shell filled, 200 lbs.[4] || 92 lbs. |
Bursting powder, 6 lbs. 2 ozs. || 2 lbs. 10 ozs. |
Blowing powder, 2 ozs. || 1-1/2 ozs. |
-------+-----------+-----+------++-------+-----------+-----+------+
Ele- | Charge. |Fuse.|Range.|| Ele- | Charge. |Fuse.|Range.|
vation.| | | ||vation.| | | |
-------+-----------+-----+------+--------+-----------+-----+------+
deg. |lbs. ozs. |inch.|yards.|| deg. |lbs. ozs. |inch.|yards.|
45 | 2 1-1/2| 1·90| 450|| 45 | 1 0-1/2| 1·90| 450|
| 2 3 | 2·00| 500|| | 1 2 | 2·00| 500|
| 2 4-3/4| 2·10| 550|| | 1 3-1/4| 2·10| 550|
| 2 6 | 2·20| 600|| | 1 4-3/4| 2·20| 600|
| 2 7-3/4| 2·30| 650|| | 1 6 | 2·30| 650|
| 2 9-1/2| 2·40| 700|| | 1 7-1/2| 2·40| 700|
| 2 11-3/4| 2·45| 750|| | 1 9 | 2·45| 750|
| 2 14 | 2·50| 800|| | 1 10 | 2·50| 800|
| 3 0-1/2| 2·55| 850|| | 1 11 | 2·55| 850|
| 3 3 | 2·60| 900|| | 1 12 | 2·60| 900|
| 3 5-1/2| 2·65| 950|| | 1 13 | 2·65| 950|
| 3 8 | 2·70| 1,000|| | 1 14 | 2·70| 1,000|
| 3 10 | 2·75| 1,050|| | 1 15-1/4| 2·75| 1,050|
| 3 12 | 2·80| 1,100|| | 2 0-1/2| 2·80| 1,100|
| 3 14 | 2·85| 1,150|| | 2 1-3/4| 2·85| 1,150|
| 4 0 | 2·90| 1,200|| | 2 3 | 2·90| 1,200|
-------+-----------+-----+------++-------+-----------+-----+------+
+------------------------------------+
| 8-INCH IRON. |
| 8 cwts. 1 qr. |
| 46 lbs. |
| 1 lb. 14 ozs. |
| 1 oz. |
+----------+------------+-----+------+
|Elevation.| Charge. |Fuse.|Range.|
+----------+------------+-----+------+
| deg. |lbs. ozs. |inch.|yards.|
| 15 | 0 14 | 0·80| 500|
| | 1 0 | 1·00| 550|
| | 1 2 | 1·10| 600|
| 45 | 0 9-1/2| 1·90| 450|
| | 0 10-3/4| 2·00| 500|
| | 0 12-1/2| 2·10| 550|
| | 0 13-3/4| 2·20| 600|
| | 0 14-1/2| 2·30| 650|
| | 0 15-1/2| 2·40| 700|
| | 1 0 | 2·45| 750|
| | 1 0-1/2| 2·50| 800|
| | 1 1-1/4| 2·55| 850|
| | 1 2 | 2·60| 900|
| | 1 2-3/4| 2·65| 950|
| | 1 3-1/2| 2·70| 1,000|
| | 1 4 | 2·75| 1,050|
| | 1 4-3/4| 2·80| 1,100|
| | 1 5-1/4| 2·85| 1,150|
| | 1 6 | 2·90| 1,200|
+----------+------------+-----+------+
+--------------------------------++--------------------------------
| 5-1/2-INCH BRASS. || 4 2-5th-INCH BRASS.
| Weight, 1 cwt. 1 qr. 10 lbs. || 3 qrs. 19 lbs.
| Shell filled, 16 lbs.[5] || 8 lbs.
| Bursting powder, 10 ozs. || 5 ozs.
| Blowing powder, 1/2 oz. || 1/2 oz.
+----------+--------+-----+------++----------+--------+-----+------
|Elevation.|Charge. |Fuse.|Range.||Elevation.| Charge.|Fuse.|Range.
+----------+--------+-----+------++----------+--------+-----+------
| deg. |ozs. dr.|inch.|yards.|| deg. |ozs. dr.|inch.|yards.
| 15 | 6 0 | 0·73| 350 || 15 | 4 8 | 0·80| 450
| | 7 0 | 0·75| 400 || | 4 12 | 0·85| 500
| | 7 8 | 0·80| 450 || 25 | 4 0 | 1·10| 540
| | 8 0 | 0·85| 500 || | | |
| 25 | 5 8 | 1·10| 480 || | | |
| 45 | 4 8 | | 300 || 45 | 2 6 | 1·65| 300
| | 4 12 | | 350 || | 2 9 | 1·70| 350
| | 5 0 | 1·75| 400 || | 2 12 | 1·75| 400
| | 5 4 | 1·80| 450 || | 3 0 | 1·80| 450
| | 5 8 | 1·85| 500 || | 3 4 | 1·85| 500
| | 5 12 | 1·90| 550 || | 3 8 | 1·90| 550
| | 6 0 | 1·95| 600 || | 3 12 | 1·95| 600
+----------+--------+-----+------++----------+--------+-----+------
[4] Shells filled with sand, which will account for the weight.
[5] Shells filled with sand, which will account for the weight.
13-INCH LAND SERVICE. 10-INCH DITTO. 8-INCH DITTO.
Greatest charge, 8 pounds powder. 4-1/2 pounds. 1 pound.
Greatest range, 2,706 yards. 2,536 yards. 1,720 yards.
WEIGHT OF LAND AND SEA SERVICE MORTAR.
Inches. cwts. qrs. lbs. Inches.
13 Land service, Weight, 36 2 0 Length, 36·563
10 do. „ 16 2 0 „ 28·125
8 do. „ 8 2 14 „ 22·500
5-1/2 do. brass, „ 1 1 15 „ 15·104
4-2/3 do. do. „ 0 3 20 „ 12·713
13 Sea service, „ 100 1 14 „ 52·810
10 do. „ 52 0 0 „ 45·620
[Illustration]
Carronades are a short description of ordnance without trunnions, but
fastened by a loop under the reinforce. Their construction is materially
different from that of guns. They have a chamber like a mortar, a part
scooped out inside the muzzle, forming a cup, and they have also a patch
on the reinforce. The name arises from the Carron Foundry in Scotland,
the first of them having been cast there in 1779. The construction is
considerably lighter than that of guns of similar calibre. Their
principal use is on board ship; but they are sometimes used in
casemates, or retired flanks of fortresses.
The proportions of all guns to shot, will be found below; and in looking
at this table, it will scarce be conceivable how such light guns can
project such heavy shot.
COMPARATIVE WEIGHTS OF GUNS AND SHOT.
-------------------+-------+-----------
|Weight |Comparative
---- | of | Weight.
| Guns. |
-------------------+-------+-----------
| cwts. |
12-inch Gun | 90 | 1 to 112
10 do. | 84 | 1 „ 82
8 do. | 65 | 1 „ 107
8 do. | 60 | 1 „ 96
8 do. | 50 | 1 „ 82
32-pounder | 64 | 1 „ 224
Do. | 56 | 1 „ 196
Do. | 48 | 1 „ 168
Do. | 40 | 1 „ 140
Do. | 32 | 1 „ 112
Do. | 25 | 1 „ 84
24-pounder | 50 | 1 „ 233
Do. | 48 | 1 „ 219
Do. | 42 | 1 „ 186
18-pounder | 42 | 1 „ 261
Do. | 37-1/2| 1 „ 233
12-pounder | 34 | 1 „ 318
Do. | 29 | 1 „ 270
Do. | 21 | 1 „ 196
9-pounder | 31 | 1 „ 285
Do. | 26 | 1 „ 323
Do. | 17 | 1 „ 211
6-pounder | 23 | 1 „ 429
Do. | 17 | 1 „ 327
68-pound Carronades| 30 | 1 „ 59
42 do. | 22-1/4| 1 „ 58
32 do. | 17 | 1 „ 62
32 do. | 25 | 1 „ 96
24 do. | 13 | 1 „ 55
18 do. | 10 | 1 „ 56
12 do. | 6 | 1 „ 56
-------------------+-------+-----------
The recoil, which in all the before-mentioned guns is very great, arises
from the blow communicated to the iron in immediate contact with the
explosive fluid. The granulatory system of the metal transmits to those
grains, or crystals, immediately behind them, the blow or concussion
they are subjected to, and these again to others, and so on, until the
vibration has passed through the metal, from the interior of the breech
to the exterior of the gun.
I am satisfied that in all small guns, from their slight substance,
recoil is communicated a great deal quicker than in larger ones; hence
arises the well-known fact that in shooting you receive a knock nearly
simultaneous with the explosion. The greater and heavier the gun (even
carry it up to General Miller’s gun of 84 cwt.) if the proportion which
the shot bears to it be not too great, the less will be the velocity of
recoil. But in carronades, as will be seen, the proportions are as high
as 1 to 55, while in long guns, it is 1 to 429; a very considerable
degree of difference.
Our ancestors had but a limited knowledge of the laws of projecting
bodies by gunpowder. Their explosive power was not good; for there is
clear proof, even since the time of Robins, that the purification of the
ingredients has nearly doubled the explosive force. The mechanical
construction and outer mould of their guns, were calculated to resist
and limit the effects of recoil to a great extent.
Accumulation of metal in the rear of the breech-end of a gun is true
science, and of so easy an attainment, that wonder arises in the mind
why it has not been effected. The extent to which this principle is
worked upon in our gunnery is very trifling; though recoil can by this
simple arrangement be nearly destroyed, or so lessened as to add
considerable percentage of range to the projectile. Add no considerable
weight to the gun, but add it judiciously, behind the end of the chamber
and vent, and immediately surrounding the breech. I have tried this to a
great extent, on a small scale, “with fowling-piece barrels,” and find
that the greatest advantage arises from an additional inch of metal to
the extreme end of the barrel, as the recoil is thereby lessened; while,
on the contrary, by reducing the exterior end of the breech, until it
becomes of less thickness than the sides of the barrel, the recoil is
doubled. Guns will some day be constructed as mortars are, with the
axles, or trunnions, in rear of the tube and of the vent; for by this
arrangement recoil would act less on the mass of metal forming the gun,
and more on the base from which it is fired. We are quite aware that an
arrangement of this nature could only be applied to certain descriptions
of ordnance, and in certain situations; but on forts, or batteries
commanding rivers and bays, and even in the bows of steam vessels, they
may be placed with great advantage. But this objection may be started:
“You could not use guns fitted in this manner horizontally, or nearly
so.” Why not? The muzzle could be as easily raised or depressed as the
breech, by mechanical means. I should much like to see the principle
tried, and I hope to do so.
The following results of experiments prove, that if a true basis is not
laid down, all the fabric raised upon it is but one of sand, which will
crumble away from under us. Hutton says,--“Varying the weight of the
gun, produced no change in the velocity of the ball. The guns were
suspended in the same manner as the pendulous blocks, and additional
weights were attached to the pieces, so as to restrain the recoil; but
although the arcs of the recoil were thus shortened, yet the velocity of
the ball was not altered by it. The recoil was then entirely prevented,
but the initial velocity of the ball remained the same.” No doubt this
was the result of his experiments by the pendulous suspension of the
gun: but here he erred; for had he suspended a thousand tons to it,
without incorporating it in the gun, the result would still have been
the same. All the improvements effected, or yet to be accomplished, will
be obtained by a concentration of metal.
An excess of weight in the fore part of a gun is very injurious, by
inducing and lengthening the tremulous vibration created by the
explosion. The only necessity for strength forward in a cannon, arises
from the necessity of resisting the lateral pressure from the
condensation of the column of air in the tube. The pressure of the
explosive gases is, by the velocity obtained before reaching the fore
part, of very little amount, from the short period it is exerted on the
interior. Therefore weight, in the fore part of a gun, be it ever so
great, will not prevent recoil if there is not a proportionate quantity
behind. It will retard or lessen the distance to which the recoil will
drive the gun and carriage, but the evil is then over.
If the slightest movement occurs in the gun, the shot is projected from
an unsound base or foundation. It is precisely similar to a man who, in
the act of throwing a stone, slips his foot backwards: the effect is at
once apparent on the stone. If the trunnion of a gun breaks in the
discharge, or a quoin flies out, the shot is materially affected; never
ranging, under such circumstances, the accustomed distance, nor with its
usual accuracy. Practice with mortars proves beyond dispute the
necessity of a firm base for the gun, for with a much less charge they
project a greater mass farther. A mortar discharged on land, exceeds in
range the same description of gun on board of ship, or on the
best-constructed platform. In truth, this is but another illustration of
a law of nature: if you have not a solid fulcrum, it matters little what
the power of your lever may be. Gunpowder is a powerful lever if
exploded on a solid base; if not, its effects become limited in
proportion. Unquestionably, much may yet be gained by an economical
arrangement of our projectile force. Great and rapid as have been the
acquisitions of knowledge in everything relating to gunnery in modern
times, there still remains, I have no doubt, an unexplored mine of
valuable treasure to be added to the science.
It would effect a great improvement in the mortars used by the navy,
destroying the tremendous vibration and shake given to the ship,
increasing their efficiency and aiding the projecting power, to place
them on beds of the softest lead, not less than twelve inches in
thickness. Though this suggestion is only theoretical, experience would
soon determine the least degree of substance available. Advantage would
arise, in the first place, from the non-conducting tendency of the lead;
in the second, from its density, and, of course, incompressibility. The
one protecting the ship, the other being the most solid bed for the
mortar that can by possibility be obtained.
The weight of a hollow 13-inch shell is 190 lbs.; the bursting powder 6
lbs. 8 oz.; the weight, if cast solid, would be 290 lbs.: thus the
action of so large a body on the atmosphere must be immense of itself.
There seems to be much difficulty in projecting masses of great
diameter, from this cause; and this should lead us to seek, as indeed it
points to, another material for fabricating projectiles. As weight is
less in substance, and, of course, less in space, much less resistance,
in proportion, will exist in a bore of six inches than in one of twelve;
and a greater projectile force will be generated with fewer
countervailing disadvantages.
The first step in the vast improvements about to be effected in gunnery,
has been successfully taken by Mr. Monk, of Woolwich arsenal, who has
induced the authorities to allow a gun to be made from drawings and
calculations of his own. The dimensions of the gun are as follows:
length from cascable to muzzle, 11 feet; weight, 97 cwt. 3 qrs.; bore,
7-7/10 inches; weight of solid shot, 55 lbs.; shell, 42 lbs.; windage,
0·175; charge, 16 lbs. of powder; giving a range, at 32° of elevation,
of 5,327 yards. _A compound shot_, (a shell filled with lead), was
projected 5,720 yards, or _three miles and a quarter_, at a velocity,
during the first second of time, of 2,400 feet per second, and occupying
during the whole flight only 29-1/2 seconds. The comparative weight of
gun and shot is 1 to 220.
A course of experiments, extending over seventeen years, has firmly
established this gun as the best ever yet constructed. Many attempts
have been made to excel it, but all have failed. Guns have been made on
drawings varying not more than three-tenths of an inch in their
dimensions from those of his gun, and, with extreme _modesty_, the
individuals have claimed a right to compete with Mr. Monk; and have
even obtained competing trials, without any claim whatever to the
discovery of the principle of it; coming into competition by no just
claim or merit, but solely from the tendency to supersede any
improvement emanating from a _civilian_. Eighteen, twenty-four, and
thirty-two pounders are now, however, constructed on this model;--indeed
the improvement is so great and so apparent, as to overcome every
obstacle as yet thrown in its way.
With no wish to detract from the merit of Mr. Monk’s invention (upon
which I congratulate him and the country) but, in justice to myself, I
may remind some of my readers, that in “The Gun,” published early in
1835, I clearly laid down the principle in _projectile force_, on which
this gun is constructed; and as he has since so successfully
accomplished this great improvement, he must permit me to say, that the
principle is the same which I have striven for, for many years.
Wilkinson says, “Guns cast on this principle, although several
hundredweight lighter altogether, recoil less than those on the old
plan, with equal charges of powder and ball, in consequence of the
weight being _properly_ distributed.” He adds, “One remarkable fact
attended these experiments, namely, that by increasing the windage a
little, the range was increased also, contrary to the received opinion;
but this may be explained by the circumstance, that with very great
velocities, and long guns, the column of air to be displaced before the
ball quits the gun is considerable, and is condensed so rapidly, that
it offers immense resistance to the passage of the bullet, if it fit the
bore closely; but, by reducing the size of the ball, and thus increasing
the windage, the air has more space to rush round it, and the ball
escapes with greater facility.”
If the condensed air prevented the velocity being greater, it argues
most clearly, that there was an insufficiency of explosive matter to
keep up the velocity until the ball of less windage left the muzzle; and
the result with the ball of greater windage establishes this assumption.
For if the condensed air was allowed to pass the ball by the windage
into the tube, it proves beyond doubt that there was a deficiency of
matter there, or that the pressure without was greater than that within.
How otherwise could such a result occur? It is a clearly established
fact, that with the generality of ordnance, a full waste of one-fourth
of explosive force, if not more, occurs by the _elastic fluid_ escaping
past the ball by the windage, instead of the reverse. Neither could the
condensed air rush into the gun by the windage if there are any
_permanent gases_ generated; which Mr. Wilkinson himself says there are,
to the extent of “250 times the bulk of the powder in grain.” These
would offer a sufficient resistance to prevent the condensed air rushing
in. I have found, by an experiment before described, that a ball driven
against a column of air which has no escape, if the velocity be
trifling, say 800 feet per second, the air will escape by the windage;
but double this even, and it is so condensed as to form a cushion for
the ball to strike against. Then how much less will the chance be of its
escaping, if the velocity become two thousand four hundred feet per
second. No, the cause is remote from that of Mr. Wilkinson’s
supposition. There is a want of force--an accelerative propellant
force--which should continue to the end of the tube, be that length ever
so great; and on this point, for one, turns the whole future improvement
of gunnery.
The result wished for can be obtained by a systematical arrangement of
the granulation of powder. That a much greater velocity than is obtained
in this gun--at present the greatest in any piece of ordnance in use,
and possessing a longer range than has been obtained by any power in
Europe--may and will be attained, I fearlessly assert. I have obtained a
velocity with an ounce ball nearly doubling this; and though, as it will
be argued, this may be too limited an experiment, yet let us not forget
that great results most frequently spring from little causes. Large
rivers owe their origin to small springs, and if the same principle by
which we can penetrate a plate of iron half an inch thick with an ounce
of lead, be fearlessly and judiciously carried through, we may (and no
doubt we shall) live to see projectiles thrown 5-1/4 miles. That this
will be difficult to accomplish I deny: no difficulty attends it,
provided the principles before explained are duly carried out.
The great principle in a propellant force is so to arrange it that you
do not obtain too great a velocity at the first move of the projectile;
as no mass can be forced from a state of rest to a rapid state of
motion, without communicating to the gun a corresponding motion, which
will create a recoil: and the greater the motion, the greater the
recoil. If the explosive matter merely expands for a brief period, and
is burnt out before the shot has reached midway the length of the gun,
the velocity there acquired will be reduced, by the condensed column of
air in the other half of the barrel, to the velocity it possessed when
only one fourth the length of the whole from the breech; consequently it
would be advantageous to cut the gun in two at the middle, as a greater
force would be then generated advantageously, than by the whole. But if
you so arrange the granulation of your powder that it shall proceed into
motion more gradually, a rapidly increasing force of elastic fluid will
continue to be generated, until it reaches its greatest maximum of
velocity (which it should do just as the ball leaves the muzzle) then
you obtain with your means the greatest result possible.
We believe that the generality of gunpowder used by our Government is
vastly inferior in strength to some made by private makers; yet it is
not advisable to jump from one extreme to another. What is wanted is the
proper blending of the qualities; an addition of a quantity of Harvey’s
quick powder to a charge, when it has driven the ball up three-fourths
of the tube of a gun, and probably had acquired a velocity of 2,000 feet
per second, might so aid it, that it would leave the muzzle with a
velocity of 3,000.
You cannot put a locomotive train in motion at once: if it were
attempted, you would break all the carriages; but if you gradually add
your force, you gain in time the greatest possible velocity. I have
drawn a parallel case: it is the same with gunpowder; only the
velocities are widely different. Therefore, I may be pardoned, if I say
gunnery is like steam, but in its infancy. Let us but clearly see and
understand aright the principle--knowing that the greater momentum the
less the action of the atmosphere--and if 3-1/4 miles can be obtained
with a ball 60 lbs. weight, 5-1/4 may be easily accomplished by a ball
of 120 lbs. Powder is made, and can be had, that will do this.
The use of compound-shot has of late years become quite common in
experiments: why lead, with its alloys, has not been more extensively
used as a projectile for large guns, has always appeared to me
extraordinary. Its weight and density peculiarly fit it for this
purpose, and its non-conducting principle is its greatest
recommendation. How is it? In no instance, except as compound-shot, do
we find any record of the use of leaden bullets on a large scale, save
in Sir Howard Douglas’s “Naval Gunnery,” where, in a note, he says, “A
very distinguished naval commander mentioned to me, that he knew a
person who had served in an American privateer, which, being out of
shot, and unable to procure a supply of iron balls, used leaden shot as
substitutes. This person always mentioned with great surprise the
superior effect of leaden balls.” Well he might; for the reader need not
be told that its greater specific gravity would add to its momentum, and
a longer medium velocity be retained during its flight. But it
possesses another recommendation, superior to all these, in warfare:
that of communicating all its force, all its velocity, be they ever so
great, to the body struck. Iron does not possess this quality; except to
a certain extent, and that at low velocities. Hence the cause of its
being found in naval warfare, that balls at low velocities damage and
destroy ships’ sides more than at higher velocities, even when passing
quite through. Lead, in the act of striking hard substances, iron or
stone for instance, is partially flattened, until the flat surface is
nearly equal to the diameter of the sphere of the ball; thus parting
with all the force it struck the object with, and in most instances
falling motionless at the base of the object struck; while in the stone,
the surrounding crystals or grains are, by their abrasion on each other,
pounded into dust, in proportion to the size and force of the body of
lead striking them: in many instances to many times the shot’s bulk, and
only flattening the lead, less or more, in proportion to the capability
of the stone to resist. Iron striking stone retains its shape: the
grains are driven back upon each other, and each offering its proportion
of elasticity, the ball is enabled to rebound back; which it does in
many instances to a considerable percentage of the whole distance it had
been projected. The greater the velocity with which an iron ball is
projected the greater the rebound back from a hard substance such as
stone. Reversely, the greater the velocity of lead, the greater its
effect on the object struck. Walls or fortifications struck by leaden
balls at the same velocities (waiving the advantage to lead by its
greater specific gravity) would be pounded into sand by less than
two-thirds the same number of lead as of iron shot. Any unprejudiced
person may soon satisfy himself of this, by trying it with a musket or
fowling piece. A leaden ball will pound itself a hole many times its own
bulk, while an iron ball will not make a hole half its size.
I have tried many experiments to ascertain the penetrating powers of
iron and lead relatively, by striking various objects, from a boiler
plate of half an inch thickness down to fir deals. The same size of lead
will, under certain circumstances, punch a perfect hole in a plate of
half-inch thickness, as I shall have occasion to show; while, under
precisely the same arrangement, the iron ball would rebound back with
very little diminution of force; and if the plate of iron be at a
perfect right angle, the iron ball would nearly return into the muzzle,
of the gun. In truth, I had a narrow escape seventeen years ago, from a
bullet actually cutting the rim of my hat: so that it will be well, when
experimenting in this way, to be sure that the person is well esconced,
for fear of unpleasant results.
Lead, therefore, for destroying ships, as well as stone walls, is
unquestionably highly advantageous; even if projected with the same
velocities as at present adopted for iron. The additional weight would
not decrease the destructive effects; it would augment them. I perfectly
agree with the American _privateer_, that the wonderfully destructive
power of leaden cannon balls will create surprise, whenever they shall
come generally into use. Imagine the effect from a gun of the
dimensions of a 10-inch bore. It is dreadful to contemplate.
The effect of lead will be easily understood when explained in the
following way. If a 36 lb. shot have a velocity of 2,000 feet per
second, the force is equal to the velocity multiplied by the weight, or
72,000 lbs. The whole of this force would strike a wall, and be left
there, if communicated by soft lead; if by iron, at the same velocity,
it would be minus the amount of force required to make it rebound to the
great distance to which iron invariably returns. Though created by the
elasticity of the iron itself, this must be deducted from the effect
produced, and hence arises the great advantage the lead possesses. We
are aware that iron driven with a slight velocity rebounds less; true,
and less is its real effect; for under the very same circumstances would
the great advantages of the lead predominate. It may be objected, that
lead is too easily misshaped; “pure it is, but with alloys not so.” At
low velocities it might, but the greater velocities diminish that
chance, as it is a well known fact that all dense incompressible bodies
are least affected by an extremely sharp motion. All our arrangements in
warlike preparations, at present, involve great weight of projectile for
fracturing, not perforating. During the siege of Ciudad Rodrigo, 2,159
rounds, of twenty-four and eighteen pounders, were requisite to form the
small breach of thirty feet wide, and 6,478 rounds for the larger of 100
feet. At Badajos there was expended, to form three breaches of 40, 90,
and 150 feet respectively, the enormous amount of 31,861 rounds of the
same sized iron shot. We may be pardoned if we presume to say, one-half
the number of lead shot would have done more, and done it better.
If we bear in mind, that the whole round of experiments from which
Hutton drew his deductions, were conducted with iron projectiles, the
inconsistency of taking his data as the standard will be apparent. The
dissimilitude of specific gravities being great, namely, 7,425 and
11,327--or one-third difference--it clearly shows, without any effort of
the imagination, that the range must be in the same proportion, with the
addition of greater momentum. For it will scarcely be denied, that a
ball of gold or platina, from the same cause, will maintain a velocity
longer, and consequently range further, than even lead. Hutton’s theory
only establishes the principle, that the lighter the body projected, the
sooner it is acted upon by atmospheric resistance, and a medium velocity
induced. We cannot attribute his preferring iron to arise from an
opinion of its penetrating to greater depths; for a man of his extensive
knowledge and research could scarcely be guilty of such an error. But
even in our enlightened times we are told that elephants cannot be
killed with any projectile but steel: leaden balls cannot do it. I
should like to try, and receive the _tusks_ in return.
The shrapnell shell (invented by General Shrapnell), or spherical case
shot, introduced into the British service of late years, is probably the
most destructive of any missile in use. It was intended to
supersede--which it has done--canister and grape shot; effecting the
same results at treble the range. The construction and principle are
very simple, being merely a shell of an unusually light description; in
fact, little more than a light cast-iron hollow ball, with a fuse hole.
A certain quantity of leaden, or iron bullets is put into it, and the
interstices around the ball shaken full of powder; a fuse of the length
required is inserted, and explodes the shell during its flight: the
peculiarity being, that the body of small balls retain their medium
velocity and travel on, merely diverging, latterly, like an immense
charge of bird shot. They are usually fired from howitzers, carronades,
and other wide bored-guns, at or near horizontal ranges. A considerable
delay occurred before they were successfully perfected. It was found
that when the small balls did not pack perfectly tight, or were packed
overtight, the case frequently exploded in the gun: occasioned, no
doubt, by the friction creating a spark at the moment of the howitzer
being fired, and thus exploding the shell before its time; but we
believe such an occurrence rarely happens now, from other improvements
since adopted.
The preceding pages appeared in my last work published in 1846. They are
still so much in keeping with the state of gunnery at the present day,
and so prophetic of what has, and is about to occur, that they will be
regarded, I trust, as bearing the stamp of authority.
Progress, in its rapid advance, has made many English guns objects for
the furnace or the museum; and many guns, which formerly ranked high as
useful and important weapons, have become things of the past.
Monsters are now all the rage, with a range of three miles, and
artillerists contemplate extending the range to double that distance;
whilst the projectiles used are not “pounders,” but approximating to
tons. So much for improvement. In political economy we are told that
improvement to be good must be gradual; but only effect some slight
improvement in gunnery, make but one step in advance, and the desire for
further improvement then ranges at will, and impossibilities are craved
for and sought to be attained.
Twelve years ago the success of Mr. Monck (certainly the first modern
improver of ordnance,) led to the unlimited production of undigested
plans for changes in gunnery; but, unfortunately for the science, no
progress was made on the one great improvement of Mr. Monck.
War found us ill prepared in the field, and out-weighted “afloat,” so
that almost as many men were killed by the bursting of mortars, and
other ill-constructed guns, as by the fire of the enemy: so critical was
our situation, indeed, that but for the general adoption in England’s
army of my great invention, the rifle on the expansive or “Greenerian”
principle, and its skilful use by our brave soldiers, the war had gone
against us. Our rifles were equal in range to our artillery, and this
saved us; whilst the enemy, astonished at the effects produced by our
bullets, and conscious of their inferiority both in the construction
and use of small arms, abandoned the contest: but no doubt with a firm
determination to profit by their dear-bought experience.
It is generally admitted that our artillery was never so effective as
that of the enemy, and that more is due to the patient and enduring
bravery of the British soldier than to our field-pieces and heavy
ordnance. That England’s artillery was at this time most disgracefully
inefficient, it would be folly to deny. The larger guns were destroyed
in an inconceivably short space of time. After five, ten, or fifteen
rounds were fired the guns burst, killing the gunners in great numbers.
The readers of my works are already familiar with my opinions on this
subject, and their value will now be enhanced by the fact that they have
been proved to be the opinions of a “practical man.” Success in the
improvement of small arms is a sure encouragement to those anxious for
the advancement of projectile science, and it is a coat of mail in which
to fight against the prejudices and incompetency of official management.
Who, on reading my work of 1841, believed the prediction I therein made,
that small arms would be produced which would render field guns useless?
The fact is, however, firmly established, that the best rifles on my
principle will out-range by several hundred yards the best “six-pounder”
in her Majesty’s service; and that, too, with a repetition of fire
wonderfully quick and effective: as the Russians in the Crimea can
testify, on more than one occasion.
To endeavour to point out that an improvement may be effected in
artillery equal to that which has been effected in small arms, is the
object of the following pages.
The author asks a dispassionate perusal and careful study of his work,
in justice to himself and to the importance of the subject. Judging of
future probabilities by what has already been accomplished, the reader
will be prepared for what follows. That great and important changes must
take place in artillery cannot be doubted, and should England refuse to
avail herself of the improvements to be effected, other nations, and
amongst them our late opponent, will be the first to seize and adopt
them. In former works I have asked the indulgence of my military readers
on account of my scanty military knowledge; but professional men appear
to be equally in the dark with the uninitiated: indeed, the lamentable
shortcomings of the English artillerists have placed them in the rank of
mere “waiters upon providence” for the next step towards improvement.
The present time is decidedly propitious; let improvements now be made,
and we may surely hope that they will be appreciated by the public, if
not by the Government authorities.
What is the best metal for cannon? is a question which has often been
asked, and the answers have been very conflicting. Some have advocated
mixtures of copper and tin; others have advocated cast iron, and more
recently wrought iron; still more recently steel, and, lastly, cast
steel, have had their advocates. Arguments as plentiful as summer
flowers have been advanced in favour of each, and the argument has been
carried on with a vast amount of prejudice and warmth, according to the
degree of acquaintance with or attachment to the favourite metal of each
individual. It is rare to meet with a mind free from bias, equally well
acquainted with the merits of the several metals, and their application
to the purposes intended. Still more rare is it to meet with a mind
possessing all this metallurgic knowledge, and combining with it an
intimate acquaintance with the principles of projectiles, as well as a
scientific knowledge of the construction of the engine (the perfection
of which consists in its having no points which are weak or
unnecessarily strong); and yet it is by such a combination of knowledge
and the application of these principles that we must be guided, if we
would be successful in the accumulation of projectile power. In the
present age we are really alive to the advantage of “playing at long
bowls;” and the question now to be determined is, what is the greatest
weight of shot and shell we can throw, and how many miles can we project
it. The Americans were undoubtedly the first to discover the great
advantage of this question with their lesser frigates; the late war has
developed it still more; and it now remains to be ascertained how much
further can we go. For on this important point the superior efficacy of
artillery depends.
At St. Sebastian, in 1813, cast-iron guns threw tons of shot at a range
of 1,500 yards; some particular guns firing as many as 3,000 rounds, and
yet it is more than probable that had the same guns been used in the
Crimea, they would have burst with one-fourth the number of rounds.
Experience proves that it is not the great number of rounds fired which
strains and destroys the gun, but the high elevation at which these guns
are placed, in order to get range; this it is which shakes and
disintegrates the crystalline structure of the metal, and thus extreme
range is obtained at extreme cost. A gun which at 6° of elevation could
stand without a strain 200 rounds, would be likely at an elevation of
30° to burst before 50 rounds were fired. The explanation of this is
sufficiently simple. A gun fired at 6° recoils as the projectile is
projected forward, in proportion to its relative weight and friction;
but when brought up to an elevation above 30° the gun is entirely out of
the horizontal, and cannot recoil as it does at an elevation of 6°: the
force is now exerted downward, and the gun impinges on its support--_i.
e._, either upon its bed on the deck of the ship, or on the solid earth
of the battery, which is comparatively immovable; thus the force which
displaced the gun in the first instance is now exerted on the sides of
the gun, and the projectile receiving additional force is projected
further. But this increased range is obtained at the expense of the gun,
which is rapidly destroyed: 50 rounds being sufficient to render it
unfit for service. To obviate this rapid destruction of cannon, the
metal has been changed from the molecular to the fibrous; that is from
cast iron to wrought iron. One object of this chapter is to point out
the difficulties which arise in determining what the best metal for
cannon really is, and to show the advantages to be gained by attending
to the proper construction of projectile engines, without attaching
undue importance to the _material_ of which they are made.
Before rejecting cast iron as useless for the construction of large
guns, it would be well to assure ourselves that no better quality of
metal can be produced than that which is at present manufactured. We
must also satisfy ourselves that we have clearly understood the proper
shape and form of cannon to resist concussions. These concussions, be it
remembered, were more violent in the late than in any previous war; and
it is an undoubted fact that we had many more fractures then than on any
previous occasion: first, on account of the strain produced by the great
elevation required to get increased range; and, secondly, on account of
the imperfect shape of the gun. The average number of rounds fired from
the 13-inch mortars which burst at the bombardment of Sweaborg was 120,
and the fracture in all was peculiarly alike; being at right angles to
the supports. Now, that this is due to the form of the gun cannot be
doubted; and it will be shown more fully in a subsequent page.
But there is another cause to which I wish now to direct attention,
viz., the jamming of the Lancaster shell, which takes place in the
increasing spiral of the oval gun at the very point where the projectile
acquires a proportional increase of velocity. The effect of this may be
illustrated by running a locomotive at its maximum of speed over an
increasing curve in the railroad, with the certainty of landing it in an
adjoining ditch. The principle which determines the result is quite
immutable: viz., that matter in rapid motion cannot be materially
affected by any force inferior to the primary force: the tendency of the
body being to go straight forward; whereas a slow train goes round a
curve with the greatest ease. Two motions can easily be given to matter
in a lower velocity; but not so easily when the velocity is much
increased. Hence I fear that the inventor of the Lancaster gun must have
had a misconception of the true laws of motion; for by increasing the
degree of spiral at the muzzle, instead of at the breech of the gun, he
has rendered nearly useless what would otherwise have proved a most
formidable engine of war.
From these observations it may, I think, fairly be doubted whether the
bursting of cannon is owing entirely to the inferior quality of the cast
iron used in their formation; though there can, I think, be no doubt
that English cast iron is not only much inferior to what it formerly
was, but that it is also inferior to that which is now manufactured in
Russia. Why it is so will be subsequently explained.
These defects in cast iron have naturally led to many attempts to
substitute for it a more durable metal; and in most cases the metal
selected has been wrought iron. Wrought iron has been used, not only in
solid cannon, but in the original “hoop and stave:” “staves outside,”
and “staves inside,” as in Mr. Mallet’s monster mortar. Forms of gun as
numerous as can be conceived have been constructed, only to prove
themselves in every case most complete failures. Our friends at the
Mersey Works, Liverpool, will, no doubt, demur to this assertion; as
“all creations of the mind appear most perfect to the father of the
thought.”
Great credit is, however, due to the enterprise and energy displayed by
the inventors, forgers, and finishers of this great gun; which has been
the wonder of many minds in this age of wonders: and it is a highly
important invention, as showing what we, as a people, are capable of
producing by our mechanical and engineering skill. But here, in my
estimation, the wonder ceases; for so sure as there is any truth in the
Scotch proverb, “A silk purse cannot be made out of a sow’s lug,” so
surely is it true that no man, however great his genius and working
powers, can make a good cannon of wrought iron. When the hardness and
ductility of silver can be imparted to and held by lead, then will it be
possible to make wrought iron accomplish all the purposes required of a
good cannon.
In vain may Mr. Horsfall urge that his gun has never been burst. Why?
Simply because it has not yet been subjected to the same amount of
pressure on the square inch; neither has it been tested at the same
elevation as some other 10-inch guns, which, in proportion to their size
have stood a more severe test. It is a fact, which may be clearly
demonstrated, that if a 10-inch gun of 95 cwt. be fired at an elevation
of 40° with 17 lbs. of gunpowder, then a gun of more than six times that
weight would not be overloaded if its due proportion of powder were
about 100 lbs. Has this gun been fired with one half of this? Until it
has been satisfactorily proved to this extent, we feel sure that the
authorities are justified in not considering Mr. Horsfall’s a successful
achievement.
Whatever may be Mr. Horsfall’s impression with regard to the advantages
of wrought iron for making cannon, I am satisfied, after a long and
careful study of the results of all its varieties, from the
most ordinary to the most perfect combination that has been
manufactured--either for tenacity, tenuity, or resistance of lateral
pressures--that it cannot answer in large guns.
This I think any one will admit, after considering the two following
facts; which apply equally to all varieties and mixtures of wrought
iron.
1. The strength of iron is at its maximum in the smallest mechanical
structures.
2. The quality of the metal is improved as it is subjected to greater
pressure and condensation.
The extent to which this improvement may be carried has never yet been
ascertained; every fresh manipulation improves its quality. The tenacity
of wrought iron is best displayed in a wire, drawn out until it is not
thicker than a human hair. Large masses of wrought iron are weak and
spongy in geometrical progression with the mass, and the crystalline or
molecular form increases with the mass. If large forgings are carefully
examined, crystals will be found whose facets would produce inches of
surface; as was clearly demonstrated by the bursting of a 10-inch gun at
Woolwich: made, if we mistake not, by Mr. Nasmyth.
Another very important cause which renders large masses of wrought iron
unsound (and which was fatal in Mr. Nasmyth’s gun) is the impossibility
of condensing tons of wrought iron equally all through the mass. No one
has yet been able to overcome this difficulty.
When the force of a blow, however great, is exerted on the surface of a
mass of metal, its effect is neutralized within a few inches of the
surface; condensation takes place in inverse ratio from the point of
impact, and thus the effect is limited. The force which produces this
condensation tends also to elongate the fibres of the metal. This
elongation is greatest in the immediate vicinity of the force; the
fibres in the interior of the mass are less elongated therefore than on
the exterior; and the fibres in the interior of the mass being less
ductile (from the cause already explained) than those on the exterior,
the interior of the mass elongates, by disintegration of its fibres or
crystals, and a porous open mass is thus produced, surrounded by a
fibrous case. Instances of this are to be seen in broken engine-shafts
and anchors; and, indeed, in all large masses of wrought iron, whether
fractured by design or accident.
Another cause of this defect in large masses of wrought iron, is the
long continued heat to which it is necessary to expose such large
forgings. The iron expands as it is heated, but it does not expand
equally all through the mass; and the result of this is that the
interior becomes porous and spongy: an appearance which must have been
observed by every one who has operated upon large masses.
The shaft of the _Leviathan_ weighs 26 tons; but, instead of resisting
twenty-six times the pressure of a shaft one ton in weight, it will,
from the causes already mentioned, be found unequal to half that amount.
We have watched with much interest the forging of these immense shafts;
and the difficulties attending the forging of this structure prove the
accuracy of our reasoning on the strength of large masses of wrought
iron. The weight of the shaft when finished is 26 tons, and the waste
during the process of welding amounts to 74 or 75 tons.
The present shaft is the third which has been manufactured; the two
first having proved notorious failures: thus 200 tons of iron have been
wasted; which we think is sufficient proof either of the unfitness of
the material, or of imperfection in the method of construction.
Moreover, I fear that when the vessel encounters a rolling sea, the
sudden check and strain produced by the total immersion of one
paddle-wheel and the freedom of the other, will subject the present
shaft to a strain which will affect its duration; and a vessel costing
nearly a million of money may thus be left to reach her port with
crippled powers of propulsion.
Where, it may be asked, is the skill in devising engines more powerful
than the ingenuity of man can beneficially work out? This has indeed
been done in the case of the _Leviathan_; a monster vessel has been
built, but all the engineering skill expended upon it has as yet been
insufficient to bring it to perfection.
The skill hitherto displayed in welding large forgings of wrought iron
into shafts, or other large masses, has been of a very low order; much
more may be done than has yet been accomplished, if men will only set
about it in a scientific manner. The present mode of proceeding is to
build a structure of iron much as a builder would raise a structure of
bricks; large and small pieces being mixed together until the requisite
mass is obtained.
Now, a much simpler method, and one which we have tried on several
occasions, is first to construct several segments of iron of the
requisite length, and of dimensions equivalent to the intended object;
each segment being fitted to fill its place amongst a given number of
other segments (whether twenty, forty, or fifty segments be required,)
so as to form a complete cylinder; as the wood-cut will fully
explain:--
[Illustration]
In welding this structure, the heat is equally diffused all through the
mass; and thus the great evil of unequal expansion and contraction is
avoided. When the steam hammer is brought into play, its face is a
“swage” of circular form, calculated to clasp a large portion of the
upper part, whilst a corresponding space is formed in the anvil; and by
gradually turning the shaft, the whole is forged into a perfect round.
The peculiar advantage gained by this mode of proceeding, is not only
the facility with which heat is diffused through the mass, but that each
segment is made to act like a wedge on its neighbour; thus producing the
most solid forging that has yet been attained. This is rendered still
more perfect, both as regards strength and durability, from the fact
that a hollow axle has been produced; the great advantages of which it
would be out of place to dilate upon in this work.
We trust that these anticipated misfortunes may be avoided by the
construction of a more perfect shaft; and that, not only for the sake of
the shareholders, but for the credit of the engineer who devised this
great vessel--deservedly one of the wonders of the world. A spare shaft
would be profitable ballast, if of no more value to the _Leviathan_.
Rolled railway-carriage axles were constructed for me with perfect
success on this principle nearly twenty years ago, at the Walker Iron
Works, near Newcastle-on-Tyne. The idea has, however, been in a measure
“shelved;” but necessity will bring it into use again.
The only engineer who has, by practical experience, satisfied himself
that large masses of wrought iron are totally useless for making heavy
ordnance is Mr. Nasmyth; whose monster cannon, which was to astonish the
whole world, proved, when heated, to have so little cohesion that it
would scarcely hold together whilst being lifted from the furnace to the
anvil. And, to his credit be it said, Mr. Nasmyth, seeing that wrought
iron would not answer the purpose, manfully gave up his hopeless task.
Similar experience would probably make some of our present engineers
wiser men.
My experience in manufacturing the largest wrought iron guns which it is
prudent to construct, sufficiently proves the truth of these assertions.
Harpoon gun-barrels, one inch and a half in the bore, having the metal
at the breech end an inch and a quarter thick, will stand a proof which
invariably bursts a thicker barrel; in fact, all experience tends to
show that light wrought iron or steel barrels are stronger than
unusually heavy ones. As all depends on the principle of condensing the
fibres of the iron, _ceteris paribus_, the greater the condensation the
greater the strength, and the less the condensation the greater the
weakness.