CHAP. XI.

Of GVNNERY.

THe General things to be known in the Art of Gunnery, next after the Names and Parts of a Piece of Ordnance (which you may [ 10] here learn from the Figure of the Gun) in order to Shoot securely, and make a good Shot, are, First, That the Piece be well Tertiated, or squa∣red upon its Carriage, and to know duly to Load and Level the Piece.

To Tertiate a Piece, is to know if it has its [ 30] due thickness of Metal at the Touch-hole, Tru∣nions, and Neck; by which you may judge at the strength of the Gun, whether well fortified, or no. This you do with a Coliper pair of Com∣passes; and if the Piece be Home boared, the Diameter less by the height divided by 2, is the thickness at any place.

To Quadrate, or Square a Piece mounted, is to see if it is directly placed, and equally poised, [ 40] which depends on the Carriage, in regard of the Wheels and Axel-Tree.

To Dispart a Piece of Ordnance, is to set such a mark upon the Muzzle-Ring, or thereabouts, that the visual Ray, or Sight-Line, taken upon the Top of the Base-Ring against the Touch-hole, by the Mark set at, or near the Muzzle-Ring, may be parallel to the Axis of the Concave Cylinder. To do this, take the Diameters of the Base-Ring, and the place at the Muzzle where you intend [ 50] the Dispart to stand; divide the difference of these two into two equal parts, one of them will be the Dispart, which you may set upon the Gun with Pitch, or Wax. If you have not Compasses, measure the Circles about, and work with them.

The Weights of Shot are regulated by the Cubes of the Diameters, and by knowing the weight of one, the weight of any other is found, thus: [ 60]

A Bullet of Iron of 4 Inches Diameter is found by Experience to weigh 9 lb. then say, as the Cube of 4 is to 9 lb. so is any other Diameter Cubed to its weight; or as 9 lb. is to the Cube of 4, so is any other weight to the Cube Root of its Diameter. Lead and Iron in weight is as 2 to 3, that is, a Shot of 2 lb. of Iron, and a Shot of 3 lb. of Lead, will have the same Diameter of height. Iron to Stone is as 3 to 8; Lead to Stone, as 4 to 1; that is, a Bullet of Stone of 10 lb. is equal in height to a Bullet of Lead of 40 lb. Therefore knowing what a Bullet of Iron of any Diameter weighs, you will find the weight of a Bullet of the same Diameter of Lead, and Stone; for Lead having the weight of 9 lb. of Iron for 4 Inches Diameter. If 3 give 2, what will 9 lb. give? Answer 6; and so of any other. As the Shot is regulated by the Cubes of the Diameters, so also is the Powder. Suppose 1 lb. ½ of Powder be a Charge for a Falcon of 2: 68 Bore of Diameter; what weight in Powder will be fit for a Charge of a Cannon of 7? The proportion is thus: As the Cube of 2: 68 is to 1 lb. ½ of Powder, so is the Cube of 7 to 26.

The Names of the Pieces of Ordnance, which are taken from the height of the Bore, are set down in the following Table, which gives in the first Column the Names of the Pieces; next, the weight of Fortified Guns; the third, the height of the Bore; the fourth, the height of the Shot; the fifth, the weight of the Shot; the sixth, Powder for Proof; the seventh, Powder for Ser∣vice; the eighth, Paces (five Foot to a Pace) the Piece shoots Point-Blank, or upon the Level; the ninth, the outmost Random, the Piece mount∣ed to 45 Degrees; the tenth, the Horses; and the eleventh, the Men required to draw a Piece of Ordnance.

As to the several Shootings in Artillery, and the knowledg of the true Distance that any piece will carry to, is a matter that depends upon many uncertainties, there being such varieties in the trueness of the Bore, in the heights of the Shot, in the strength of the Powder, in the Disparts, in the Levelling, and Direction, in the Air, Wind, &c.

The Ball, when it is Shot, flies through the Air with a violent, mixt and natural Motion, describing a Parabolical Line, in whose beginning, and end are Lines sensibly streight, and in the middle, Curved. The Shootings, or Shots in Artillery, are therefore three; The first is called Point-Blank, which is Page  188 that Space, that the Ball flies in a Line sensibly right without any inclination; The second is called the Mean, which comprehends all that Space the shot flies in a Curved Line; The third is called the Dead-Shot, which is the fall of the Ball by a sensible right Line towards the Ground, after that the violence is ceased.

Gunners do take notice of these three differ∣ences, and Ranges of Shot, for three several ends. The Shots of Point-Blank serve to Batter the [ 10] Ramperts and Walls of Forts, and Castles; the Mean, or Middle Range to molest afar off the Troops in the Campaign, and in their Quarters, and to ruine the Houses within the Cities, and Castles, &c. The Dead-Shots serve for Mortars to shoot Bombs, and other Artificial Fire upon the Enemy, especially when they cannot be other∣wise offended, nor seen; being covered behind with Ramperts, Trenches, Hills, and other Emi∣nencies. [ 20]

A shot Point-Blank, which is the most ordina∣ry and most Important, is distinguished, in re∣gard of the Horizon, and in regard of the Ob∣ject which it strikes. As to the Horizon they are of three sorts, First, Level; Secondly from Low to High; Thirdly, from High to Low, called Vnder Metal.

The Horizontal, and by the Level of the Chase, or Concave Cylinder is the most secure, and certain. [ 30]

That from Low to High, proves fallacious, because by the Recoyling which the Piece makes, the Shot flies higher than the Mark; and that from High to Low is most fallacious, because the Shot (besides other notable effects) comes more Low by the Recoyling of the Piece. There∣fore an experienced Gunner must remedy these faults by taking the due advantages in Shooting.

As to the Object, a Shot Point-Blank is made either at right Angles against the Superficies of [ 40] the Object, or at oblique Angles. At right Angles it strikes more furiously than at oblique; therefore it is used against strong Walls, to batter them; and are used to make Batteries of several Tire, and discharging them against the self-same Mark, and in the same instant. At oblique An∣gles they strike either Cross-ways, or Rebound∣ing, like a Tennis-Ball. If they strike Cross-ways, with two Batteries one upon each side of the Ob∣ject, it ruines more speedily the Defence either [ 50] of Earth, or Wall; if they batter Obliquely, or by a Rebound, which is done when they cannot do it right forward: As if one would batter a Flank covered with an Orillon, or Shoulder, one must strike the Curtain in so fit a place, and ob∣liquely, that by the Rebound the Shot may leap into the Flank; holding it for a Maxim in this Operation, That the Angle of Incidence is equal to the Angle of Reflection.

The Mean or middle Ranges are diverse, ac∣cording [ 60] to the different Elevations of Ordnance; the Elevations are regulated by the Gunners Square, which is an Instrument made of Brass or Wood▪ of two right Lines (See Fig. 10 Plate 1) one longer than the other, both which make a right Angle, from which as from the Center is described an Arch divided into 90 Degrees, or into 12 equal Parts, called Points; so much of the Arch as exceedeth a Quadrant, as 45 Degrees, or 6 Points, serves for shooting below the Hori∣zon, as the Quadrant doth for above. From the Center hangs a Thread with a Plumet, the longest Leg put into the Chase, or Concave Cylinders of of a Piece of Ordnance, the Thread cutting the Arch, doth shew the Degrees of Elevation, or Depression, one never exceeds 6 Points, or 95 Degrees of Elevation in shooting with long Can∣non.

The Dead-Shot which is made with Mortars, is done by giving Elevation from the Points 6, or 95 Degrees, to the Point 12, or 90 Degrees, which are measured with the Square, or with a particular Instrument like a Level, putting a Staff across the mouth of the Mortar, and upon that the Quadrant.

In Shooting in these its observed, that at the sixth Point is the farthest off, and that at the seventh Point comes the nearest, and at the eighth Point nearer; and so nearer and nearer to the twelfth Point, in which the Bomb falls in the same place from which it departed.

Of Shots made out of Mortars, betwixt the Middle or Mean-Shot, and the Dead-Shot, it is to be observed by Experience, those are equal which are equally removed from the sixth Point of the Quadrant, viz. that the Bomb fall as far distant, being shot from the same Piece, and with the same strength at the fifth as at the seventh Point, and the same thing at the fourth as at the eighth, and as much at the third as at the ninth, and second as the tenth.

Shots from Mortar-Pieces are very fallacious, sometimes flying farther, somtimes shorter than needs, and the Bombs break in the Air; some∣times after the fall they do not break, which gives time to the Enemy to retire, or to Choak it; therefore to have a just Blow, and to take effect, these following Advertisements must be observed.

First, One ought to know how many Paces are to the place which you would shoot, which may be done with an Instrument.

Secondly, That the Bombs, or other Bodies, which are to be Shot, be of equal weight, other∣wise the Shots will vary.

Thirdly, That the Carriage in breadth be al∣ways upon a Level, and without any Descent, that it do not leap in Discharging.

Fourthly, That the Powder with which the Mortar is loaded, be always of the same force and weight.

Fifthly, That the Charge of the Mortar, as well in Powder as in Wadding, be always ramm'd in with Blows equally heavy, and of equal number.

Sixthly, That the Fusees be newly made in those days they are to be used, and that they be made of a mixture proportionable to the Range the Shot shall make in the Air, and that it break in the very Fall; which Skill is in the Fusee filled with mixture of Composition, which is to be such, that although the Bomb fall in the Water, it ought to break.

Page  189 To measure a just Time, is done by filling the Fusee after the ordinary manner; take a small Barrel or Cane of Iron of equal Bore to that of the Fusee, but something longer, with many little Holes all along its length, and filling it in the same manner as the Fusee, then the Bomb being fitted in the Mortar, you give Fire at the same time to the Fusee in the Mortar and the Iron-Barrel, letting the Barrel burn until you see the Bomb break, in which moment, you [ 10] observe the Barrel, and to what Hole the Fire burns down, which will give an assured mark of the time the Fusee ought to have.

If the Bomb in the very Fall shall break, the same quantity of Composition should be continued in the Fusee, but if it break before the Fall you must abate the Heat, by adding a small mixture of Charcoal-Dust incorporated in the same Composition; and if after its Fall it shall delay its effect, then you shall joyn with its mixture a little fine Powder-Dust, and so you may by Experience with this Barrel observe in∣to what Mark or Hole it burns, so that with such Fusees the Bomb shall justly break in the very Fall amongst the Enemies, observing al∣ways to fill the Barrel with the same mix∣ture.