The mariners magazine, or, Sturmy's mathematical and practical arts containing the description and use of the scale of scales, it being a mathematical ruler, that resolves most mathematical conclusions, and likewise the making and use of the crostaff, quadrant, and the quadrat, nocturnals, and other most useful instruments for all artists and navigators : the art of navigation, resolved geometrically, instrumentally, and by calculation, and by that late excellent invention of logarithms, in the three principal kinds of sailing : with new tables of the longitude and latitude of the most eminent places ... : together with a discourse of the practick part of navigation ..., a new way of surveying land ..., the art of gauging all sorts of vessels ..., the art of dialling by a gnomical scale ... : whereunto is annexed, an abridgment of the penalties and forfeitures, by acts of parliaments appointed, relating to the customs and navigation : also a compendium of fortification, both geometrically and instrumentally / by Capt. Samuel Sturmy.

SECT. III. The Description and Use of the Gunners Scale, upon which is all sorts of Ordnance, from the Canon, to the Base of their Weight, Lading, Shot, and all other things appertaining to them.

THis Scale is made according to the Diameter of our English Ordnance, but 8 inch. long, the Diameter of a Canon-Royal; and it may be made of Silver, Brass, or Box, or any other f••••e grained Wood, that will not warp. Upon one side I have set the Names of all sorts of Ordnance, and in the Angle of meeting with the Names, is the diameter of the bore; and betwixt that and the next less diameter, is first the com∣mon length of such Pieces; and upon the step of breadth, is how many Paces these Pieces shoot point blank, and right in the Angle of meeting, betwixt the two diame∣ters with the Angle of meeting with the Names, is first the weight of the Gun, the breadth of the Ladle; and thirdly, the length; fourthly, the weight of the Charge in Powder; fifthly, the diameter of the Shot; sixthly, the weight of the Shot; seventhly, a Line of Inches; eighthly, each Inch divided into 10 parts, and likewise into 8 parts, which are parts and half quarters, which the Line of Diameters of the bore comes from. The degrees in the divisions, and on the thickness and length thereof, there is a Line of Numbers, by which you work all the most useful Questions in Gunnery, as you will find in the following page.

The Use of this side is thus.

Suppose you come to a Piece of Ordnance, and it is desired to know what Piece it is; take the Scale, and put it into the bore of the Piece, mark the step of a Diameter that fits it, and the Angle of Diameter goes down into the Line of Inches, and parts, and that diameter goes into the side in the Angle of meeting, and tells you the Name of the Piece: Betwixt the next less Diameter, right under, you have as before, the common weight of the Piece, the breadth and length of the Ladle, weight of Powder, diameter of Shot, and weight.

As for Example.

Admit I came to a Gun, and found by the former directions, that her diameter of the bore is 4 ¼ Inches. And in the Angle of meeting in the side, I find her Name is Demi∣culvering, lower then ordinary; at the end thereof I find 9 or 10 foot the usual length, and betwixt the next less diameter and the step is 174 the paces the Piece carries the Bullet in a level-line, point blank, right against weight in the next less Diameter, which is 4 Inches, is the usual weight 2000 l. breadth of the Ladle 8, and length 12 Inches, the weight of the Powder 6 ¼ or 4 ounces; and next the diameter of the Shot 4 Inches; and next, the weight 9 l. So that you see the next less diameter is the diameter of the Shot, as well as of a less Piece of Ordnance. This I have made plain to the meanest ca∣pacity: Here they are set down in this Table following.

The Explanation of the Scale may serve likewise for the Table; only take notice, that under Inches and Parts, is to be understood the first; to the left hand is Inches, and the other is so, many 8 parts of an Inch.

As for Example.

Admit you enter the Table with a Saker of the lowest sort, the height of the bore is 3 4/8 Inches, 8 foot long, the weight 1400, breadth of the Ladle 6 4/8, length 9 6/8 Inch. weight of the Powder 3 pound 6 ounces, diameter of the Shot 3 2/8, weight of the Shot 4 pound 12 ounces, and the paces the Piece carries, by Alex. Bianco's Tables is 150 of 5 foot to the Piece.

Observe that the Ladle is but 3 diameters of the Shot in length, and 3/5 parts of the Circumference from the Canon, to the whole Culvering, I allow the Charge of Pow∣der to be about two diameters of the Piece: from the Culvering to the Minion; the Charge to fill two diameters and a half; all from the Minion to the Base three dia∣meters of Powder.

The names of the Pieces of Ordnance.	Diameter of the Bore.	Length of the Gun.	Weight of the Gun in pounds.	Breadth of the Ladle.	Length of the Ladle.	Weight of the Powder.	Diameter of the Shot.	The weight of the Shot.	He shoots point blank.
The	Inches. Parts.	Feet. Inches.	Pounds	Inches. Parts.	Inches. Parts.	Pounds. Ounces.	Inches. Parts.	Pounds. Ounces.	Paces.
	⌊8	⌊8		⌊8	⌊8		⌊8
A Base.	1:2	4:6	200	2:0	4:0	0:8	1:1	0:5	60
A Rabanet.	1:4	5:6	300	2:4	4:1	0:12	1:3	0:8	70
Fauconets.	2:2	6:0	400	4:0	7:4	1:4	2:2	1:5	90
Faucons.	2:6	7:0	750	4:4	8:2	2:4	2:5	2:8	130
Ordinary Minion.	3:0	7:0	750/800	5:0	8:4	2:8	2:7	3:4	120
Minion of the largest size.	3:2	8:0	1000	5:0	9:0	3:4	3:0	3:12	125
Saker the lowest sort.	3:4	8:0	1400	6:4	9:6	3:6	3:2	4:12	150
Ordinary Sakers.	3:6	9/9:0	1500	6:6	10:4	4:0	3:4	6:0	160
Sakers of the oldest sort.	4:0	10:0	1800	7:2	11:0	5:0	3:6	7:5	163
Lowest Demiculvering.	4:2	10:0	2000	8:0	12:0	6:4	4:0	9:0	174
Ordinary Demiculvering.	4:4	10/10:0	2700	8:0	12:6	7:4	4:2	10:11	175
Elder sort of Demiculvering.	4:6	12/13:0	3000	8:4	13:4	8:8	4:4	12:11	178
Culverings of the best size.	5:0	12/10:0	4000	9:0	14:2	10:0	4:6	15:0	180
Ordinary Culvering.	5:2	12/13:	4500	9:4	16:0	11:6	5:0	17:5	181
Culvering of the largest size.	5:4	12/10:0	4800	10:0	16:0	11:8	5:2	20:0	183
Lowest Demicanon.	6:2	11:0	5400	11:4	20:0	14:0	6:0	30:0	156
Ordinary Demicanon.	6:4	12:0	5600	12:0	22:0	17:8	6:⅙	32:0	162
Demicanon of great size.	6:6	12:0	6000	12:0	22:6	18:0	6:5	36:0	180
Canon Royal, or of	8:0	12:	8000	14:6	24:0	32:8	7:4	58:0	185

The Description of the other side of my Gunner's Scale.

Upon the other side is a Scale of 8 Inches divided into four quarters, and betwixt each quarter above it is three Columns; the Inches shews the height of all sorts of Iron shots from 2 ounces to 72 pound; and of Lead from 3 ounces to 806 pound ½, and of Stone from 1 ounce to 26 12/16 pounds; each distinguished from other by their names, written in the first Inch, the Table is in the sixth Section, and the weights and measures, accommodated into our English Averdupoiz weight of 16 ounces to the pound, and to our Foot of Assize of 12 Inches to the Foot. The Line of Inches being likewise di∣vided into 10 parts, the whole into 80, may serve for 800; for Protraction as follows: There is also the Gunners Quadrant divided into 90 degr. in the outmost Limb, and in the second Limb within, is divided into the 12 points of the Gunner's Quadrant, and

[illustration] geometrical diagram with representation of a cannon

each point 4 parts; and in the third Limb is a Geometrical division of right and contrary shadows, for the ready taking of heights and distances; but there is also a Geometrical Quadrate, with each side divided into 10 parts, which stands for 100, and each 10 parts divided into 10 more, the Use thereof in taking of heights and distances is in the 16 Chap. of the Second Book of the Description of Instruments: But the Use for to level, or else to mount or Imbase any piece of Ordnance, is in the 34 Sect. of this Book. To the side thereof is fitted a piece of Brass of the same breadth as the Scale in thick∣ness, with two holes within an Inch of each End, and two Screws fitted to serve the four holes, as you may see in the Figure to the side of the Scale, that if you would level or mount any piece of Ordnance, Screw the plate to the end of the side B, with both Screws, and put the plate in the bottom of the metal as far as he will go, and put the tomping in upon him to keep the plate fast, and then level or mount your Piece, as in 33 Section directed.

But if you will Imbase any piece of Ordnance to any place or point assigned, you must screw the plate to the end A, and let the side with the Line of Numbers be next the muzzle, and stop him with the tomping, as before; then Imbase your Piece, or put him under the Line of Level as you will, to what degree you please; and when you have done, screw the plate to the side A B, with a screw at one end, and a screw at the other, (there is also over the weight of the Shot a division of the right Ranges, and likewise a proportion of Randoms of any piece of Ordnance, upon any mounture from degree to degree; and likewise you may put the division of Inches in the 38 Section, for the number of Inches and parts from 5 foot to 14 foot long, requireth to mount her to any degree of mounture with great facility and ease. There is also Triangle-wise a plain Scale, that goes along down by the degrees of diameters, or steps, the Line is a Line of Chords, with the Gnomon-line, and a Line of six hours of the same Radius, and a Line of Rhumbs, with the Line of Sines; and this is for the making any sort of Dial in any Latitude by the following directions, and also for the Plotting any Triangle, or resolving any Question in Navigation, or Astronomy. You must remember, there is a Brass Pin in the Center at C for to hang the Plummet and String, with the Lope upon.

Thus I hope I have fitted all ingenious Gunners with a Scale so useful, that I will leave it to them to give me commendation for my labour and pains. If I might advise Gun∣ners of all sorts, that are able to have one of these Scales of Brass or Wood, to carry a∣bout him, to resolve any Question presently for his own credit, and it is very portable and fit for his Pocket; but it is best to have a case of Leather or Cloth to keep it clean; and you may carry a pair of Compasses with him, and by him you may resolve most of all the Questions in this Noble Art of Gunnery.

On the side of the Quadrant betwixt the Equinoctial, and the Radius, or Suns great∣est Declination is a division to every 10 minutes of the Suns Amplitude Rising and Set∣ting answerable to the Ecliptick Line, and the Declination on the other side the Figure, makes all plain to any Instrument-maker; without further precept.