Read Ebook: The hand-book of artillery by Roberts Joseph

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Ebook has 311 lines and 32828 words, and 7 pages

An instrument made of sheet-brass; the lower part is cut in the form of a crescent, the points of which are made of steel; a small spirit-level is fastened to one side of the plate, parallel to the line joining the points of the crescent, and a slider is fastened to the same side of the plate, perpendicular to the axis of the level.

To mark the points of sight on pieces.

It is a graduated quarter of a circle of sheet-brass, attached to a brass rule 18 inches long. It has a vernier turning on a pivot, to which is attached a spirit-level. To get a required elevation, the vernier is fixed at the indicated degree, the brass rule is then inserted in the bore parallel to the axis of the piece; the gun is then elevated or depressed until the level is horizontal.

To facilitate the handling of the piece in mounting and dismounting it, and moving it when off its carriage.

Two handles placed upon the piece with their centres over the centre of gravity, by which it is mounted or dismounted.

Only the 12-pdr. brass guns, and the 24 and 32-pdr. brass howitzers.

It is the excess of weight of the part in rear of the trunnions over that in front; it is measured by the weight which it is necessary to apply in the plane of the muzzle to balance the gun when suspended freely on the axis of the trunnions.

To prevent the sudden dipping of the muzzle, in firing, and violent concussion on the carriage at the breech.

Inserting a piece of metal about an inch in diameter , through the centre of which the vent has been previously drilled. It is screwed in.

Pure copper always, which is not so liable to run from heat as gun metal.

To prevent deterioration of the vent, or provide a new one when this has already occurred.

No, only bronze pieces, and iron pieces, only when repeated firing has rendered it absolutely necessary.

If the spike is not screwed in or clinched, and the bore is not impeded, put in a charge of powder 1/3 of the weight of the shot, and ram junk wads over it; laying on the bottom of the bore a slip of wood, with a groove on the under side containing a strand of quick-match, by which fire is communicated to the charge. In a brass gun, take out some of the metal at the upper orifice of the vent, and pour sulphuric acid into the groove, and let it stand some hours before firing. If this method, several times repeated, is not successful, unscrew the vent piece if it be a brass gun; and if an iron one, drill out the spike, or drill a new vent.

Unscrew the vent piece, if there be one, and drive in wedges so as to start the shot forward; then ram it back again in order to seize the wedge with a hook; or pour in powder, and fire it after replacing the vent piece. In the last resort, bore a hole in the bottom of the breech, drive out the shot, and stop the hole with a screw.

Flashing off a small quantity of powder to clean out the bore; about 1-12 of the shot's weight. The practice is discontinued.

Pieces rejected on inspection are marked X C on the face of the muzzle; if condemned for erroneous dimensions which cannot be remedied, add X D; if by powder proof, X P; if by water proof, X W.

They are little subject to such injury, except from the bending of the trunnions sometimes, after long service or heavy charges.

Internal injuries are caused by the action of the elastic fluids developed in the combustion of the powder, or by the action of the shot in passing out of the bore.

When the surface of the bore is full of small holes or cavities.

To the melting and volatilization of a portion of the tin in the alloy; tin being much more fusible than copper.

They do.

To the above defects in a less degree than brass, except the corrosion of the metal, by which the vent is rendered unserviceable from enlargement. The principal cause of injury to iron cannon is the rusting of the metal, producing a roughness and enlargement of the bore, and an increase of any cavities or honeycombs which may exist in the metal.

Generally by the appearance of the vent.

ON GUNS.

Long cannon without chambers.

The cascable, breech, reinforce, chase, and muzzle.

It varies from 15 to 23 calibres.

About a sixtieth part in field guns, about a thirtieth part in sea-coast, and about a thirty-eighth part in siege and garrison guns.

One degree and thirty minutes.

One degree.

Because the swell of the muzzle is not visible when the eye is on a level with the base ring.

On field, siege, barbette or casemate carriages.

Solid shot, spherical case, grape, and canister.

ON HOWITZERS.

A chambered piece, of larger calibre than a gun of like weight, and mounted in a similar manner.

That of a cylinder.

They project larger shells than the guns with which they are associated, are well adapted for ricochet fire, the destruction of field works, breaking down palisades, and setting fire to buildings.

Shells usually, spherical case, canister, grape and carcasses.

Iron 10-inch, 124.25 inches; 8-inch sea-coast, 109 inches; 8-inch siege and garrison, 61.5 inches; 24-pdr. garrison, 69 inches; 32-pdr. field, 82 inches; 24-pdr. field, 71.2 inches; 12-pdr. field, 58.6 inches; mountain, 12-pdr., 37.21 inches.

One degree.

Thirty-seven minutes.

Because the swell of the muzzle is not visible when the eye is on a level with the base ring.

ON COLUMBIADS.

A gun of much larger calibre than the ordinary gun, used for throwing solid shot or shells.

Its carriage gives a vertical field of fire from 5? depression to 39? elevation; and a horizontal field of fire of 360?.

Those of the old pattern have chambers; but they are now cast without any.

ON MORTARS.

The shortest piece in service; the trunnions are placed in rear of the vent at the breech; the bore is very large in proportion to the length, and is provided with a chamber.

Reaching objects by their vertical fire--such as a town, battery, or other place--whose destruction or injury cannot be effected by direct or ricochet fire; dismounting the enemy's artillery; setting fire to and overthrowing works; blowing up magazines; breaking through the roofs of barracks, casemates, &c.; and producing havoc and disorder amongst troops.

That produced by firing the mortar at a high elevation.

The shell having attained a great elevation, descends with great force on the object, in consequence of the constant action of the force of gravity on it.

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