PART XII.

BATTERIES, AND FORTIFICATION.

BATTERIES.

A BATTERY, in respect to its profile, may be either elevated, half sunken, or sunken; and it is usually reveted with gabions, fascines, sand bags, &c.

An elevated battery has its whole parapet raised above the natural surface of the ground, and, to procure the mass of earth required, a ditch is usually dug directly in front of the parapet.

A half-sunken battery has its interior space, or terreplein, sunk some inches below the natural surface, and its parapet is composed of the earth thus obtained, and of that taken from a narrow ditch in front.

A sunken battery has the whole of the earth taken from the interior space to form the parapet; and it must therefore be lowered from 2 feet to 3 feet 6 inches, according to the height of the gun carriages to be used.

The half-sunken battery is constructed the quickest, as the diggers can work both in front, and rear, at the same time. In a sunken battery, the diggers are as much crowded as in an elevated one, but, since the mass of parapet to be raised is smaller, it may be completed in much less time.

Casemates, or vaulted batteries, are made bomb-proof, and the embrazures are cut through the revetment.

Barbet batteries have no embrazures, the guns being placed on traversing platforms to enable them to fire over the parapet.

A direct fire from a battery is when the line of fire is perpendicular to the parapet, and an oblique fire when it is oblique. The direct fire being preferable, the battery should be placed parallel to the object against which the fire is to be directed.

The line of fire is an imaginary line drawn through the centre of an embrazure, in the direction of the object against which a battery is constructed.

Embrazures are openings cut through parapets, flanks of bastions, &c., for guns to fire through.

The neck of the embrazure is the inward, or narrowest part of it. The mouth of the embrazure is the outward, or widest part of it. The sole of the embrazure is the bottom, or space, between the cheeks, or sides.

The sill is the front of the sole.

The genouillere is that part of the parapet which is beneath the sill of the embrazures.

The merlon is the portion of the parapet contained between two embrazures.

The following dimensions are requisite to be proof, Against musketry.--3 feet

6 inches

12 inches

5 inches

9 inches

Against cannon.-4 feet, when of wood, or brick.

when of earth.

6 feet against 6-pounders, when of earth.

Note.-A 6-pounder shot, with a charge of one pound, will penetrate a mass of ice to the depth of 4 feet, at the distance of twenty-one yards.

GENERAL DIMENSIONS OF AN ELEVATED GUN BATTERY,
reveted with fascines.

Space from the centre of one embrazure to that of the next,

without traverses

Ditto, with traverses

Slope of the interior revetment, per foot (one-fourth its height)
Fall of the superior slope,

ditto (one-twelfth ditto)

Interior width of embrazures, measured on the sill

Exterior ditto, measured on the sole, at 12 feet from the sill Slope of the cheeks of embrazures at the neck, per foot (onesixth of their height)

Ditto, at the mouth, per foot (one-fourth their height)

slope of an adjoining traverse

ft. in.

18 0

Distance from the centre of an embrazure to the foot of the

7 6

Distance from the centre of an embrazure to the foot of the slope of an adjoining epaulment

2

Batteries at sieges are generally traced in the dusk of the evening. Detail of Men, and tools required:

Tracers.-1 non-commissioned officer, and 2 privates.

Tools.-1 ground-square. 1 measuring tape.

1 white tracing-line. 2 ten-feet rods.

1 mallet.

1 bundle of pickets.

Directions. The tracing-pickets, and mallet, are carried in a sandbag, and a few long pickets are necessary to mark the embrazures.

A line should be stretched about 40 feet in the direction of the object against which the battery is to be erected; this will show the line of fire. By means of a ground square, a line may be laid down at right angles to the former, touching the first placed picket. This will be the interior base line. Another line must be placed parallel to this, at a distance equal to the sum of the breadth of the base of the parapet, breadth of the berm (if any), and breadth of the slope of the ditch (viz., about 27 feet), which line will represent the reverse slope of the ditch. A picket is then driven in on the interior base line, where it is intended to have one extremity of the battery, and as many long pickets (18 feet apart), measuring from this end, as there are guns, which will mark the centre of the embrazures. Then one more picket, 18 feet distant from the last, will show the other extremity. For the embrazures, drive in a picket at the distance of one foot on each side of the centre of the embrazures, for the width of the neck. Set off, and drive in pickets 3 feet 6 inches on each side of, and perpendicular to the line of fire, for the width of the mouth.

WORKING PARTY; TOOLS; AND MATERIALS REQUIRED for each gun; mortar; traverse; or epaulment; in an elevated fascine battery.

2 sappers, with 6 assistants, to revet the work.

12 infantry, to excavate the ditch, and form the parapet.

9 pickaxes, 15 shovels, or spades, 14 fascines, 18 feet long, 1 bundle of 50 pickets to 6 fascines, 3 mauls, 3. rammers, 1 saw to every two guns, 1 hatchet per gun, 1 bill-hook, 1 field-service level, 1 six-feet rod, 1 bundle of matches to every three guns, 1 lantern, do., 1 lb. of candles, do., 1 bundle of gads to each gun, 1 tape of 50 feet in length per battery.

A battery will seldom be completed in less than 24 hours, when executed by inexperienced workmen; but by those inured to hard labour, and with proper reliefs, in about 10 hours. In light soil, that can be easily dug without the aid of a pickaxe, a man can, in 8 hours, load from 19 to 20 cubic yards of earth on barrows. If a pickaxe be required, 2 men will do the same quantity of work. A man can wheel 20 cubic yards of earth per day to a distance of 30 yards on level ground, or 20 yards on a ramp. Twenty cubic yards of earth will fill 500 wheelbarrows. When near the surface, in soil requiring but little the use of the pickaxe, an excavation of 6 cubic yards in a day of 8 hours would be a fair task for a soldier, who in general is little accustomed to working with the pickaxe, and shovel.

SHELTER FROM AN ENEMY'S FIRE.*

The following method of sheltering the workmen from the enemy's fire was used with great success during the construction of the batteries. It was towards the end of the siege that Lieutenant

* Vide-"United Service Magazine," No. CCCVIII.

Neandre received orders to construct a battery 130 paces from the counterscarp, the covered way being strongly occupied by the enemy. Foreseeing the difficulties that would occur, Lieutenant Neandre provided 120 common platform planks, and, when the gabions were in their places, arranged the planks outside them, in such a manner as to present an inclined plane, (one end of the plank being supported on the gabion, and the other end resting on the ground towards the enemy): the gabions were then half filled with earth, and the pickets driven in. At this moment the enemy threw some fire balls, and fired a few shot, all of which went over. Soon after, the workmen were assailed with a well-sustained fire of musketry; but, on the balls striking the epaulment, they ricoched, and passed over the workmen, so that not a single man was hit. The battery was finished in a few hours, when the planks were drawn in, and used for the platforms.

A portable framework might be rapidly made, and used instead of the gabions, to obtain immediate cover from musketry fire; and, for sapping, the framework, with the planks fixed thereon, might be readily moved on trucks, as a substitute for the present sap roller.

EPAULMENTS.

Batteries at sieges are generally secured on one flank at least, by a parapet called an epaulment, forming an obtuse angle with that of the battery. Their use is to secure the reverse of the terreplein from any flanking fire, and they are not in general made so thick as the parapet, being seldom subject to a direct fire.

ELEVATED SAND-BAG BATTERIES.

The base of the interior slope of a battery reveted with sandbags is rather broader than that of one reveted with fascines, being about one-third the height of the parapet. Bushel sand-bags are now the only kind in use, and when filled are of the following dimensions:

Length 20 inches, breadth 10 inches, depth 5 inches.
Number required per gun,-for the interior revetment 262

for the cheeks

360

622

Sand-bags are laid header, and stretcher, as in masonry; the ends which are tied being always hid. As the sand-bags near the neck of the embrazure would be destroyed after a few hours' firing, and constantly require repairing, gabions, or casks should be substituted for them.

Howitzer batteries are similar to those for guns, except that the interior openings of the embrazures are 2 feet 6 inches, and the soles are raised, towards the front, about 10°, in order to cover the gunners as much as possible.

Mortar batteries are constructed with the same dimensions as gun

batteries (the parapet being generally 8 feet high, and from 18 to 22 feet thick), but, as they have not embrazures, the ditch of elevated batteries is made two feet deeper to obtain the requisite quantity of earth. A preference would in general be given to the sunken, or half-sunken profile for a mortar battery, on account of its requiring less time for its construction, and it being of no consequence whether the platforms are sunken, or otherwise. Mortars are placed at the distance of 15 feet from centre to centre of each other, where no traverses intervene; and the parapet has the same profile as a gun, or howitzer battery.

When fired at 45° they are placed 12 feet from the revetment.

Ditto 300

The sill is about half its total height above the natural surface of the ground; the most convenient depth to which the terreplein may be sunk is 2 feet. The height of a sill for a travelling carriage will be 18 inches, and for a garrison carriage one foot above the natural level. The profile of the parapet is the same as in an elevated battery.

Number of sand-bags required for reveting one merlon.
Ditto ditto
for cheeks of embrazures.

180

360

In forming the epaulment of a half-sunken battery, the earth is taken from a ditch in front, six feet wide, and about five feet deep.

SUNKEN GUN BATTERIES.

The soles of the embrazures are on a level with the natural ground, therefore the terreplein is sunk a sufficient depth for the solid, and the merlons are formed of the excavated earth. The height of the solid depends on the nature of gun carriage to be used. The first operation is to trace out the embrazures. The profile is the same as in the elevated battery. Should there be traverses, all the earth excavated from the interior will be required; if not, the overplus may be scattered in the rear.

RICOCHET BATTERIES.

Ricochet firing is the art of projecting shot, or shell, with a certain velocity, and in such a direction as to insure its striking the ground at any spot that may be required; afterwards making several grazes upon the earth, and destroying, or striking all that may oppose its progress. The piece of ordnance is loaded with a diminished charge of powder, and the elevation is from 3° to 10°, which causes the shot to bound or hop along the ground. The smaller the angle under