GUNS.
Guns are distinguishedfrom each other by their metal, and weight of their shot.
A Gun is divided into five parts, which are namedCascable,First reinforce,Second reinforce,Chase,Muzzle.
The metal is made thicker towards the breech than at the muzzle, to strengthen the piece, for the elastic force of the Gunpowder is there greatest, and diminishes in power as the space it occupies is extended. The metal is made thinner towards the muzzle to make the gun lighter.
The Dispartis half the difference between the diameter of the Gun at the base ring and at the swell of the muzzle. By affixing on the muzzle a piece of metal equal to the height of the dispart, the line of sight will be made parallel to the axis of the bore, and therefore an object within point blank range can be seen. Howitzers, and some guns which have a patch or projection on the upper part of the muzzle, have no dispart, the semi-diameter of the muzzle with the patch added to it being equal to the semi-diameter of the base ring. Iron ordnance (Bloomfield’s) are intended to have a degree and a half dispart, but the founder is allowed two-tenths of an inch variation in casting Iron ordnance, for any difference which there may be between the intended and actual diameter of the base ring and muzzle.
Light Brass Field Guns 12, 6, and 3-pounders have a dispart of one degree, and Medium 12-pounders and 9-pounders have one degree and a quarter.
The Angle of dispartis the number of degrees the axis of the bore would point above the object aimed at, when laid by the surface of the gun.
Point blank rangeis when the piece is laid at the object without any elevation; the plane and the axis of the bore being parallel to each other.Its distance is measuredfrom the muzzle of the piece (fired with the service charge of powder) to the first graze of the shot, or point at which it first touches the ground.
When a Shot is fired from a gun, it is acted upon by three forces:—
1st. The explosion of the Powder, which urges it forward.
2nd. The resistance of the Air, which tends to stop it.
3rd. The force of gravity, which causes it to descend.
A BRASS GUN.Gun barrelNAMES OF THE SEVERAL PARTS OF A GUN.ABLength of the GunACFirst ReinforceCDSecond ReinforceDEChaseEBMuzzleFACascableGHBoreRHAxis of the PieceITrunnionsLVent FieldNVentOSwell of the MuzzleVAKBreechSButtonabButton AstragalcdNeckefNeck FilletgBreech OgeehBase RingiBase Ring OgeekVent Field Astragal & FilletslFirst Reinforce RingmSecond Reinforce Ring & OgeenMuzzle Astragal & FilletsoMuzzle MouldingssShoulder of the TrunniontuDiameter of the Bore or Calibre
A BRASS GUN.
NAMES OF THE SEVERAL PARTS OF A GUN.ABLength of the GunACFirst ReinforceCDSecond ReinforceDEChaseEBMuzzleFACascableGHBoreRHAxis of the PieceITrunnionsLVent FieldNVentOSwell of the MuzzleVAKBreechSButtonabButton AstragalcdNeckefNeck FilletgBreech OgeehBase RingiBase Ring OgeekVent Field Astragal & FilletslFirst Reinforce RingmSecond Reinforce Ring & OgeenMuzzle Astragal & FilletsoMuzzle MouldingssShoulder of the TrunniontuDiameter of the Bore or Calibre
ABLength of the GunACFirst ReinforceCDSecond ReinforceDEChaseEBMuzzleFACascableGHBoreRHAxis of the PieceITrunnionsLVent FieldNVentOSwell of the MuzzleVAKBreechSButton
abButton AstragalcdNeckefNeck FilletgBreech OgeehBase RingiBase Ring OgeekVent Field Astragal & FilletslFirst Reinforce RingmSecond Reinforce Ring & OgeenMuzzle Astragal & FilletsoMuzzle MouldingssShoulder of the TrunniontuDiameter of the Bore or Calibre
When a Shot has been fired from a gun one second of time, it has fallen 16-1/12 feet; in two seconds, 64⅓ feet; in three seconds, 144¾ feet; and proportionally for every additional second.[4]For this reason, it is necessary to give a certain degree of elevation to a gun: as, for instance, shouldthe time of flightof a shot be two seconds, the gun must be pointed 64⅓ feet above the object intended to be struck, because in that time it will have fallen through that space; therefore, the more distant the object is, the greater must be the elevation given to enable the shot to reach it.
There are three modes of extending the range of a Shotwithout increasing the charge of powder, viz.:—
1st. By raising the piece to a higher level.
2nd. By giving its axis greater elevation.
3rd. By excentric projectiles; recent experiments having shown that if the centre of gravity is placed directly above the centre of figure the range is greatly increased.[5]
A Tangent scaleis affixed to the breech of Guns and Howitzers, by means of which the requisite elevation may be given, and the object seen at the same time. This scale has divisions, called degrees, marked on it, and it is placed in a groove at the breech, from which it can be raised (being fastened by a screw) to give the necessary elevation.
The divisions on the Tangent scaleare found by multiplying the length of the piece in inches, from the base ring to the swell of the muzzle, by ·017455, and the product will give the length nearly of each degree or division on the tangent scale. By subtracting the dispart from this product, the length of the tangent scale above the base ring for one degree of elevation will be obtained.
The Sights of a gunare two small notches marked on the upper part of the base ring (or on the top of the tangent scale) and swell of the muzzle. Their situation is ascertained by means of a spirit level.
The line of metalis an imaginary line drawn along the surface of the metal between the two sights.
The line of metal Elevationis obtained by laying a Gun at an object by means of the sights, without giving any elevation; from the thickness of metal at the breech, the line of metal elevation varies from one to two degrees.
The Centre of metalis indicated by a line drawn through the uppermost point of the base ring and swell of the muzzle; and is ascertained by means of a spirit level.
Windageis the difference between the diameter of the bore, andthat of the shot. The windage formerly allowed was one-twentieth the diameter of the shot, but it is now reduced considerably: (Field Guns having only one-tenth of an inch) and this diminution of windage is very beneficial, longer ranges being obtained with the same charges of powder, and also greater precision of fire.
The Vent, for every nature of Ordnance, is two-ninths of an inch in diameter.
Bouching a gunis fixing a pure copper vent into it; which is done by drilling a hole in the piece, where the vent is usually placed, about one inch in diameter, and screwing therein a piece of wrought copper with a vent of two-ninths of an inch through the centre of it.
Tertiating a gunis examining the thickness of metal, whether the bore is perfectly straight, the trunnions properly placed, &c. It is performed by means of calliper compasses, and other instruments.
Quadrating a gunis ascertaining if it is properly placed on its carriage, and if the wheels are of an equal height.
A Gun is honeycombedwhen the surface of the bore has cavities, or holes in it.
The Length of a gunis ascertained by measuring it from the rear of the base ring to the face of the muzzle.
The Calibre of a gunis the diameter of the bore.
To find the length of a gun, in feet and inches, its length in Calibres being known—
Divide the product of the number of Calibres and the diameter of the bore, in inches, by 12, and the quotient will be the length in feet and inches.
To find the Number of calibres in the Length of a gun.
Divide the length of the gun in inches by the number of inches in the calibre.
Gun metalis a compound of 8 lb. or 10 lb. of tin, to 100 lb. of copper. The property of tin being to harden, the largest proportion (10 lb.) is used for mortars, they requiring a greater degree of hardness than guns.
Ordnance cast of gun metal are generally designatedBrass Ordnance.
Brass gunsare used for field batteries, they having been considered preferable to iron for the service, being lighter than iron guns could be cast of the same calibre, without risking their bursting.
Brass gunsare, however, soon rendered unserviceable by repeated and quick firing.
Iron gunsare better adapted for batteries in the attack or defence of towns or fortresses, and also for service on board ship; being less expensive than brass, and better able to sustain long-continued and rapid firing. At the siege of Badajoz the firing continued for 104 hours, and the number of rounds fired from each 24-pounder averaged 1249; at the siege of St. Sebastian, each piece fired about 350 rounds in 15½ hours. None of these guns were rendered unserviceable;but three times the number of brass guns would have been required to produce the same effect, or maintain such long and rapid firing.
Service Charges of powder.
The Point blank range of Iron32, 24, 18, and 12-pounders with solid shot varies from 380 to 260 yards; from which to 1200 yards, every ¼ degree increases the range about 100 yards; and from 1200 to 1500 yards, every ¼ degree increases the range about 50 yards.
The Point blank range of Brass, Medium 12, 9, and Heavy 6-pounders, with solid shot, is 300 yards, and from which to 700 yards, every ¼ degree elevation increases the range 100 yards; from 700 to 1000, every ¼ degree increases it 75 yards, and from 1000 to 1200, every ¼ degree increases it 50 yards.
The Point blank range of Brass, Light 12, 6, and 3-pounders is 200 yards, from which to 600 yards, each ¼ degree increases the range 100 yards, and from 600 to 1000, each ¼ degree increases it 50 yards.
Note.—For Weights, Dimensions, Ranges, Charges, &c., videTables.
HOWITZERS.
Howitzersare a short description of Ordnance, either Brass or Iron, and are used for projecting Shells. Their principal advantages are that they can be more easily loaded, and are considerably lighter, in proportion to their calibre, than Guns; and they also may be used as Mortars. They have no dispart, the diameter of the base ring and swell of the muzzle being equal, except in the 24 and 12-pounders; which, however, are provided with a patch to make up the difference.
Millar’s howitzersdiffer from the old pattern in the increased length, being from six to ten calibres; and in the conical form given to their Chambers (calledGomer) which are the frustrum of a cone, terminating in an hemisphere.
Note.—Vide Tables for Weights, Dimensions, Ranges, Charges, &c.
CARRONADES.
A Carronadeis a short piece of Iron Ordnance, with a loop under the reinforce instead of trunnions. Its construction is materially different to that of guns; having a chamber; a part scooped out inside the muzzle forming a cup; also a patch on the reinforce. They take their name from the Carron Foundry (where they were first cast for the Navy in 1779), are considerably lighter than Guns of similar calibres, and are fired with charges of about one-twelfth the weight of the shot.
Carronades are chiefly used on board ship, but occasionally in casemates, and retired flanks of fortresses.
Note.—For Weights, Dimensions, Ranges, &c., videTables.
MORTARS.
Mortars differ from Guns in the construction of their bore, and also in their form, which is considerably shorter, the metal being much thicker, and the trunnions being at the extremity of the breech.
They are used for throwing Shells into a town, or battery, setting fire to and overthrowing works, blowing up magazines, and breaking through the roofs of barracks, casemates, magazines, &c. They are distinguished from each other by the diameter of their bore. Their chambers are in the form of a frustrum of a cone, in which the powder is more concentrated; the Shell fits close to the sides of the piece, and thereby receives the whole force of the expansion of the powder. The greatest charges their chambers will contain, and the corresponding Ranges, are as follows:—
When Mortars are used in firing on Inclined planes, up or down hill, should the inclination be considerable, take half the angle it makes with the horizon, and add it to, or subtract it from 45 degrees (which is for a medium plane), and it will givethe greatest range upon the required plane.
Note.—Vide Tables of Dimensions, Weight, Charges, Ranges, &c.
VALUE OF ORDNANCE.
BRASS ORDNANCE.
Dependent on the market price of metals; at £100 per ton, after their combination, the value of gun metal is from 4 pence to 4½ pence per lb.
IRON ORDNANCE.
The value is variable according to the market price. Average from £14 to £16 per ton, according to the nature of the ordnance, the higher price being the value of the smaller pieces.
PROOF OF ORDNANCE.
All natures of Ordnance undergo several kinds of proof before they are received into the service:—
1st. They are gauged as to their several dimensions, internal and external; as to the justness and position of the bore, the chamber, vent, and trunnions, &c.
2nd. They are fired with a regulated charge of powder and shot, being afterwards searched to discover irregularities, or holes produced by the firing.
3rd. By means of engines, an endeavour is made to force water through them.
4th. They are examined internally by means of light, reflected from a mirror.
IRON GUNS.
The guns are first examined as to their proper dimensions, in which no more than ·3 of an inch variation is allowed; and in the diameters of the bore only ·033 from 42 to 18 pounders, and ·025 from 12 to 6 pounders; but in the position of the bore ·5 of an inch out of the axis of a piece from a 42 to an 18 pounder, and ·334 of an inch from a 12 to a 6 pounder is allowed.
They are then fired twice with the charge in the following table, with one shot and two high junk wads, and examined with a searcher after each round.
In this examination they must not have any hole or cavity in the bore of two-tenths of an inch in depth behind the first reinforce ring, or one-fourth of an inch in depth before this ring.
BRASS GUNS.
From 3 to 12 pounders the diameter of the bore must not vary more than ·025 of an inch, nor in any dimensions more than ·2.
The 12 pounders are fired twice, the remainder three times. Any hole ·15 of an inch upwards, or sideways in the bore, or ·1 in the bottom, between the breech and first reinforce; or ·2 of an inch upwards, or sideways, or ·15 in the bottom of the bore before the first reinforce ring, will be sufficient to condemn them.
MORTARS, AND HOWITZERS.
The exterior dimensions are in no respect to deviate more than ·1 of an inch in the 10, and 8 inch Howitzers, and ·05 of an inch in the 24, and 12 pounder Howitzers, and Royal and Coehorn Mortars, and Howitzers. Their bores and chambers must not deviate from their true diameters, or positions more than ·025 of an inch.
PROOF CHARGES.
The Brass Mortars, and Howitzers are fired twice with their chambers full of powder, and an iron shell. The Mortars on their own beds at an elevation of about 75 degrees, and the Howitzers on their carriages at an elevation of about 12 degrees. The Iron Mortars are proved with a charge equal to the full chamber, and a solid shot equal in diameter to the shell. Royal or Coehorn Mortars, and also 24, and 12 pounders, or Royal Howitzers, having a hole of ·1 of an inch in depth in the chamber, or ·15 of an inch in the chase are rejected. A hole ·15 of an inch in depth in the chamber, or ·2 of an inch in the chase is sufficient to condemn the 10 and 8 inch Howitzers.
CARRONADES.
The bores, and chambers of Carronades must not deviate more than ·05 of an inch from their true dimensions, and positions.
PROOF CHARGES.
They are proved with two rounds, with their chambers full of powder, and one shot and wad. A hole of ·2 of an inch in depth in the bore, or ·1 in the chamber condemns the piece.
WATER PROOF.
All Ordnance, after having undergone the before-mentioned proofs, and the subsequent searchings, are subject to theWater proof. This is done by means of a forcing pump, having a pipe or hose fitted and secured to the mouth of the piece, and a plug to stop up the vent.
After two or three efforts to force the water through any honeycombs or flaws, which there may be in the bore, they are left to dry, and generally the next day examined by light reflected from a mirror. If the bore should contain any small holes or flaws, which have not been discovered by the former proofs, they are very readily found by this, as the water will continue to weep or run from the holes, after the solid parts of the bore are perfectly dry.
When a gun bursts in proving, the remainder in proof at the same time are subjected to another proof round.
Ordnance condemned, for any of the foregoing reasons as unserviceable, is marked as follows:—
INSTRUCTIONS FOR THE CARE AND PRESERVATION OF IRON ORDNANCE.
Great attention should be paid to the care and preservation of iron Ordnance when in Depôt or on Service, to prevent the irreparable injury Guns sustain from rust and corrosion.
With this view the first step to be taken is to clear their bores and exterior surfaces from all rust and dirt, which is done on the inside with circular Spring Scrapers, fixed on the end of a long shaft or handle, these scrapers are made to press strongly on the sides of the cylinder, and by being drawn backwards and forwards by two or three efficient labourers, will remove the rust, and if not in a very bad state, will restore a regular smooth surface; the bottom or end of the bore is also scraped with a tool for that purpose, and the vent is opened by passing a square steel rimer of its diameter through it, gently turning the tool round until the vent is clear; after which the bore must be well brushed out, first with a hard round brush, and then with a Turk’s-head brush, so that not the least dirt remains in it. This being performed, the first coat of lacquer may be laid on, to which when dry, a second is to be added. This is done with a common painter’s brush, fixed vertically on the end of a staff sufficiently long to reach down the cylinder; and the bottom of the bore is lacquered by another brush fixed horizontally at the end of the staff; the outside or exterior parts of the pieces are also to be well scraped with an old sea-service sword, or steel tool of that nature, tolerably sharp, especially about the mouldings, where former coatings and dirt have accumulated, and when the rust will not give way, it should be slightly hammered, so as to loosen it. These operations must be continued until the whole coat of old paint, rust, or dirt, is completely removed, after which the dust must be well brushed or rubbed off, and the piece will then be fit to receive its first coat of anticorrosion, to which, when dry, a second is to be added.
Before the work is commenced the pieces should be arranged as nearly as possible in the places where they are to remain, as too much rolling is apt to disturb the coating of paint, especially before it has gained sufficient hardness to be durable.
The following objects also require to be particularly attended to—viz.:
In skidding Guns, &c., care must be taken that they are laid under metal, so that their muzzles may be sufficiently inclined downwards to prevent rain or any moisture lodging, and the bores from time totime should be swept out, as dust or sand blowing into them and being suffered to remain, would be very destructive; nor should the Guns be ever stacked one over the other, if the space where they are kept is sufficiently large to admit of their being laid in single tiers.
After the Ordnance is once got into a complete state of preservation, by following these instructions, very little trouble or expense will attend their being kept so, for a slight coat of anticorrosion on the exterior, and a thin coat of lacquer in the cylinder every three or four years, is all they will require, provided they are every now and then brushed out as before stated.
On coating the Guns, it may be found useful to let the painter mark on them the date, which will show how long it lasts, as this may differ at different stations, especially such as are exposed to much damp air, and it will afford the means of calculating the necessary demands of articles for this purpose at stated periods.
The same rules are to be observed in the preservation of all iron Ordnance mounted on works, with regard to the application of lacquer and anticorrosion, and the precautions of keeping the pieces laid under metal, and frequently brushing out their bores, &c., as recommended in the foregoing instructions.
MIXTURE OF INGREDIENTS FOR COATING AND LACQUERING IRON ORDNANCE.
This mixture, when well stirred and incorporated, will be fit for use, but, as by long keeping in this state it becomes hard, no more should be mixed than is required for present use.
BLACK LEAD LACQUER, FOR THE BORE OR CYLINDER.
The oil to be boiled, and the paint to be well ground. This will keep. Great care should be taken in boiling the oil, as any damp falling in would cause an explosion.
INSTRUCTIONS FOR LACQUERING SHOT, AND SHELLS.
All Shot and Shells (including Shrapnell) are first to be cleaned exteriorly by the machine or otherwise, and then such as are found sufficiently correct and up to their proper gauge are to be twice lacquered with the following composition, leaving sufficient time between for the coats to become perfectly dry and hard. The warmest weather is the proper time for this operation. Ten labourers can examine,clean, and lacquer with two coats one thousand shot in a day, provided the weather be favourable.
COMPOSITION.
Grant’s black 40 lb. Red lead 5 lb. Raw linseed oil 5 gallons.
The red lead is to be ground into a part of the oil, in order that the whole of the ingredients may be thoroughly incorporated.
TO RENDER ORDNANCE UNSERVICEABLE BY SPIKING, ETC.
The most effectual method of rendering Guns unserviceable, or of no further use, is by removing one or both of the trunnions, which may be done by striking it near its end with a sledge hammer; or by firing a shot against it from a carronade, or howitzer, the muzzle of the piece being placed near the trunnion.
Brass Ordnance may also be rendered unserviceable by firing whole or broken shot into the bore from another piece; or by filing a shot against the chase, which generally bulges the metal within the bore.[6]
For spiking Ordnance, two kinds of spikes are used:—
1st.The Common spike, which is 4 inches long, ·27 inches in diameter at the head, and about ·1 at the point. It is driven as far as it will go into the vent, and afterwards broken off close to the gun.
2nd.The Spring or temporary spike, which is ·17 in diameter, and varies in length from 3·25 to 5·25 inches. It has a flat head to prevent its falling through the vent into the bore, and also a spring about two inches in length, which extends from the point towards the head. In passing through the vent, this is compressed, but as soon as it is clear of the metal, it expands and cannot be withdrawn, unless it is again compressed sufficiently to allow its being again drawn into the vent, which may be done by pressing a rammer head against it, provided the spring is towards the muzzle, which may be known by a small notch cut in the head of the spike to point out its direction.
A long spike with a soft point may be driven into the vent, and the end projecting into the bore clenched; which, as well as either a common nail or even a wooden peg would answer as a temporary expedient if a proper spike were not at hand. Should a momentary abandonment of the guns become unavoidable, by taking away the cap-squares, elevating screws, quoins, linch-pins, or side-arms, the Enemy will be prevented using them for some time.
An artilleryman should, however,never forgetthat theguns are his Standard, which it should be his pride and glory to defend tothe last moment, never deserting them without positive orders to do so,or until the last glimmering hope of saving them is destroyed. But should the necessity of abandoning the guns appear imperative, then let the Artillerist remember that aparting shot(especially canister) at the advancing columns of the enemy, may insure not only his own safety, but also that of a large portion of the army.
UNSPIKING ORDNANCE.
If a gun has been spiked with a Common steel spike, load with a charge of powder equal to half the shot’s weight: lay a leader of quick match along the bore, and double shot the gun, introducing the shot, however, very carefully.
By affixing a piece of slow match to the end of the quick match which reaches to the muzzle, the gun may be easily and safely fired. Should the spike not be removed, the operation may be repeated.
When Brass guns have been spiked, it would be advisable, a day or two before making the above experiment, to scratch round the spike with a graver, and pour a few drops of Sulphuric, or Nitric acid into the circle, which, being repeated, will find its way down between the spike and the metal, particularly if the former is not perfectly round. When the gun cannot be unspiked by the above-mentioned operations, make a large fire round the breech to soften the spike, and after the gun has been gradually cooled, the spike may generally be removed by using the drill.
When a gun cannot be unspiked, the only means of rendering it serviceable is to drill another vent, about half an inch from the original one.
To drill a new Ventwill require about an hour per inch. Care must be taken that a very small drill is first used, and afterwards one rather less than the diameter of the vent, otherwise the vent will run the risk of being too much enlarged.