DIvide the Bore of the Piece into twenty equal Parts, and one of these Parts is sufficient vent for any Piece, the rest of the nineteen Parts must be the heighth of the Shot : But most Gunners now-a-days allow the Shot to be just one quarter of an Inch lower than the Bore of the Piece, which rule makes the Shot too big for a Cannon, and too little for a Faulcon ; but if the Mouth of the Piece be grown rounder than the rest of the Cylender within by often shooting ; to choose a Shot for such a Piece, you must try with several Rammer-heads, until you find the Diameter of the Bore in that Place where the Shot useth to lye in the Piece, and a Shot of one twentieth part lower than that Place, is sufficient.

Every Gunner ought to try his Piece, whether it be not wider in the Mouth than the rest of the Chase, and then proceed to chuse his Shot.

This word Tertiate is a Term principally used by foreign Gunners, meaning thereby only the measuring and examining the Fortification of Metals in a Piece, tertiating ; because it is chiefly to be measured and examined in three principal Parts of a Piece, Viz. at the Breech, the Trunions and the Mouth : And there are three Differences in Fortification of each sort of Ordnance, either Cannon or Calverings, for they are either double fortified, ordinary fortified or lessened, as Legitimate, Bastard, or extraordinary Pieces : For the Cannon double fortified or re-inforced, hath fully one Diameter of the Bore in Thickness of Metal at her Touch-hole, and 11/16 at the Trunions, and 7/16 at her Muzzle; and the ordinary Cannons have 7/8, at the Chamber ½, at the Trunions 3/8; The lessened Cannons have 11/16 at the Chamber, and 9/16 at the Trunions, at the muzzle 5/16, &c.

Now that every Gunner may be assured of the Fortitude of any Piece of Ordnance, and so may the more safely and boldly allow her a due Loading and Proportion of Powder, both for Proof and Service, that she may without danger perform her utmost Execution, you may observe this following Direction :

Suppose there is a Culvering that shooteth an Iron shot of 17 l, with 13 l. of Corn-Powder, which is 4/5 of the Weight of the Shot ; the Question is, whether she may be able to bear so much Powder, and if need were, more which question cannot be well answered without examining or tertiating her Metal, which may be thus performed.

First with a Ruler draw a Line upon a Paper or Slate, as you may see in the annexed Figure, as the Line AB.

Then with a Pair of Compasses with reversed Points, take the Circumference of the Bore of the Piece, and Measure the same upon an Inch-Rule.

Then take the same Measure from any other Scale of equal parts of a competent size, and divide that distance into two equal parts with your Compasses, and having that distance in your Compasses, set one foot in the Point C, and describe the circle D E F G, which circle is equal to the bore of the Piece.

Then with a pair of Calaber Compasses, take the Thickness or Diameter of the Metal at the Touch-hole, and Measure the same upon a rule as before, and take that distance between your Compasses, and with half that distance setting one Foot in the point E describe the circle H I K L, which shall represent the circumference of the Metal at the Touch-hole, so that you may take the Compass and Measure the Diameter of the Bore G E, which is equal to the distance of L G or E I which shews, that there is one Diameter of Metal round the Concave Cylinder of the Piece; you may therefore be sure that it is an ordinary fortified Culvering ; but to know if it be a Bastard, or extraordinary Culvering, it cannot be known by the fortification but by the length thereof, being longer than ordinary, it is therefore called an extraordinary Culvering, and being shorter than the ordinary, it is therefore called a Bastard Culvering.

Now this being found to be an ordinary Culvering, she will bear 4/5 of the weight of her shot in Cannon Powder, which is 13 l. 9 ounces.

But to be more assured of her fortitude, the measure of her Metal may be taken at her Trunions and Neck as followeth.

At the cornishing before her Trunions, with a pair of Calaber Compasses, you may take the Diameter of the body of her Metal there, as you did before at the Touch-hole, and measure the same Diameter upon a rule, then take your Compasses and from the same scale as you did use before, take that distance and divide it in two equal parts, and setting one Foot of the Compasses in C descibe the circle M N, and if found 7/8 of the Bore, it is the proportional fortification for an ordinary Culvering, and the like may be done with the Neck which the circle O P doth represent, and the distance from G to O being ½ of the height of her bore, and is the due thickness of her Metal, for an ordinary Culvering at her Neck.

But if in taking the measures aforesaid there had been found at the Touch-hole from G to L (the thickness of one Diameter at the Bore, and 1/8 more, it would have signified that it had been a double fortified or a reinforced Piece, having also at the Trunions G M 11/16, and at the neck G O 9/16 of the height of her bore, then she shooting an Iron shot of 17 l. would have endur'd 17 l. of Cannon Corn Powder to be loaded with, and to be fired without danger, and would conveyed the shot further than the ordinary could have done upon the like degrees of Mounture.

Contrariwise, if the Circles there had been found that from G to L had been but 7/8 of the height of her bore at the Touch-hole, and at her Trunions but ¾ which is G M, and at the Neck from G to O but 7/16 of the height of the bore, then she would appear to be one of the lessened or slender fortified Culverings, and must be allowed but 12 pound 9 ounces of Cannon Corn Powder, to convey her shot of 17l. which upon like elevation will not carry a shot as far as the ordinary.

In this manner all other Guns are to be measured and tertiated only with this allowance withal that the Demy Culvering hath 1/14 and the Saker 1/21 and the Falcon 1/  more Metal comparatively than the whole Culvering hath.

And if a Piece is found that it is not truly bor'd, you must always reckon that the Piece is no otherwise fortified than she is found to be, where her Metal is found to be thinest.

IN time of service when you are on a suddain to make a Shot at a Ship, and know not what dispart will serve the Piece, then you must take your aim at what part of the Ship you judge to do most execution, and look along by the side of the Piece, as near as you may at the middle of the Breech unto the middle of the Mouth of the Piece, and so place her to the best advantage, and quoin up the tayl of the Piece fast (for that giveth the true height of the mark) Then minding the steeridge take your best opportunity and give fire, and if the Sea be any thing grown, choose your Piece that is nearest the Main-Mast and in the lower Teer, if the Ship can keep her Ports open, for there she doth least labour; and when you are to make a Shot at a Ship, you must be sure to have a good Helms-Man that can steer steady.

And he that giveth level must lay his Piece directly with that part of the Ship that he doth mean to shoot at. And if the Enemy be to Leeward of you, then give fire when the Ship doth begin to ascend or rise upon a Sea, which is the best opportunity that doth present.

But if the Enemy is on the weather-gate of you, then wait an opportunity when the Ships do right themselves; for if you should give fire at the heelding of your Ship, then you would shoot over the other Ship; and if the Sea be high, there is no better time to give fire than when your Enemies Ship begins to rise on the top of the Sea, for then you have a better mark than when she is in the trough of the Sea : All which several observations must be managed, with a good judgment and discretion of the Gunner.

And if in a fight, if you intend to lay your Enemy, aboard then call up your Company either to enter or defend.

And if you are resolved to enter, then be sure to level your Bases or other small Guns ready to discharge to the best advantage you can at the first boarding, at such a place where his Men have most recouse, and if you can possibly, at boarding endeavour to take off his Rudder by a great shot, or at his Main Mast &c.

IT is first to be considered that the carriage be made in such sort that the Piece may lie right in the middle of the Port, and that the Trucks or Wheels are not too high, for if they are too high, then it will keep the carriage, that it will not go close to the Ships side, so that by that means the Gun will not go far enough out of the Port, except the Piece be of a great length ; and also if the Shops heelds that way, the Trucks will always run close to the Ships side, so that if you have occasion to make a shot, you shall not bring the Trucks off the Ships side, but that will run too again ; and the Wheel or Trucks being too high, it is not a small thing will stay it, but will run over it.

And another inconveniency is, if the Trucks are too high, it will cause the Piece to have a greater reverse or recoyl, therefore for these reasons it is good to have low Wheels or Trucks to a Gun aboard of a Ship.

The best position that the Gun can be in is, to place it in the very midst of the Port, that is to say, that the Piece lying level at point blank, and the Ship to be upright without any heelding, that it be as many Inches from the lower side of that Port beneath, as it is upon the upper part above; and the deeper or higher the Ports are up and down, it is the better for making of a shot, for the heelding of a Ship, whether if be on the Lee or Weather side ; for if you have occasion to shoot forward or backward, the steeridge of the Ship will serve the turn.

It is also very bad to have the Orlope or Deck too low under the Port, for then the Carriage must be made very high, which is very inconvenient in several respects, for in firing the Piece it is apt to overthrow, as also in the working and labouring of the Ship in foul weather.

And also you have consideration in placing your Ordinance in a Ship, for the shortest Ordinance is best to be placed out of the Ships side, for several reasons.

1. For the ease of the Ship, for the shorter they are the lighter, and if the Ship should heel with the bearing of a Sail, then you must shut the Ports, especially those Guns on the lower deck ; then the shorter the Piece is, the easier it is to be taken in both for the shortness and weight also.

2. In like manner, the shorter the Piece lyeth out of the Ships side, the less it shall annoy them in the tackling of the Ships Sails, for if the Piece lyeth far out the Sheets, Tacks or Bowlines, it will be apt to be foul of the Guns.

For your long Guns they are best to be placed in the Gun-Room or any place, after on for a Stern-Chase, for two Reasons.

1. The Piece had need to be long, or else it will not go far enough out that it may be no annoyance to the works of the Stern that may over-hang, and so may blow away the Counter of the Ships Stern.

2. The Pieces that are placed abaft, are required to be long, because of the raking of the Ships Stern from below, so that the Carriages cannot come so near the Ports as they do by the Ships side, which is more up and down.

Also for such like Reasons as these, it is as well required to have long Pieces to be placed forward or in the Fore-Castle, &c.

And here note that there must be regard had to the making of the Carriages, both for Forward-on or After-on for the places of the foremost trucks, in taking notice if the Ships side do tumble in or out, and also the cumbering of the Deck or Orlope ; in all these cases it must be left to a good judgment and experience, in the convenient placing of Guns in a Ship.

YOU may observe this Rule, that as many Feet as your Piece is in length, so many Fathom must your Rope be.

They must always be four times the length of the Piece with some overplus for fastning at both ends. If in foul weather your Breechings and Tackles should give way, you have no better way for the present to prevent danger, than immediately to dismount the Piece.

It is also approved by able Gunners, that the Rammers and Spunges made with small Hawser should be armed close and hard with strong and twisted Yarn, from the Rammers end quite to the Spunge, which would much stiffen and make it more useful and lasting to ram both Wad and Bullet close to the Powder.

Let the head of the Rammers be of good Wood, and the heighth one Diameter, and ¾ thereof in length, or very little less then the heighth of the shot next the Staff; it must be turned small that a ferril of Brass may be put thereon, to save the head from cleaving ; when you ram home the shot, the heads must be bored ½, for the Staff to be put in and fastned with a Pin through, and the Staff-length a foot more then the concave of the Gun.