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. XXXII. How to Order and Direct a Piece, and amend an ill Shot that was made, either by the Metal, Level, Right-line, or Advantage, or Mount.

AFter you have made one Shot, and find the Piece carry just over the Mark, then do all as hath been before taught again; and when your Piece lies directly against the Mark, observe how much the last stroke of the Shot is above the Mark, so much longer make your Dispert, that the top of it may be just seen from the Britch of the Piece in a direct Line with the stroke of the Shot; and being so fitted, Level your Piece with this new Dispert to the assigned Mark, give Fire, and without doubt it will strike the same; if the first Shot had struck under the Mark, then bring the Piece in all points, as before; mark how much of the Dispert is over the Shot, and cut it just so short, as being at the Britch, you may discern the top of it, the Mark of the Base-Ring, and the stroke of the Shot in a Right-line, when you percieve it is of such a length, Level the Piece to the intended Mark as at the first, Prime, and give Fire.

If the first Shot had struck on the right Hand of the Mark, to mend it, you must Level the Piece as formerly, you standing behind the Britch of the Piece, observe the stroke of the Shot over the Dispert, that part of the Base-ring which you at that instant looked over in a Right-line towards the Dispert, and the stroke of the Shot, set up a Pin with a little soft Wax on the Base-ring, so this Pin will be in a Right-line with the Dis∣pert and stroke, then Level your Piece to the Mark intended by this Pin, and the first Dispert, and without question you will make a fair Shot; for when you Level by the Metal of the Base-ring where the Pin is placed and the Mark; the Piece standing at that direction, look over the top of the Dispert from the Mark in the Base-ring, and you shall find the Piece to lie just so much to the left, as the former Shot struck to the right, from the intended Mark, which should in all likelihood now strike the Mark.

But if the Shot be both wide and too low, then you must use both directions, as before taught to make the next Shot; first regulate the Dispert by cutting it shorter, according as the Mark of the Shot is lower than the intended Mark, then by the last Rule mend the Shooting wide; these things done with care and diligence, you may be sure will mend a bad Shot.