The arte of gunnerie. Wherein is set foorth a number of seruiceable secrets, and practical conclusions, belonging to the art of gunnerie, by arithmeticke skill to be accomplished: both pretie, pleasant, and profitable for all such as are professors of the same facultie. / Compiled by Thomas Smith of Barwicke vpon Tweed souldier.

Another way to know the thicknesse of mettall in any part of any peece of Artillerie.

Take a letherne girdle, and gird about that part of the peece you desire the thicknesse of mettall, lay the same measure to an inch rule, and note how many inches or other measure the same containeth: then multiply that measure by 7, and deuiding the product by 22, your quotient is the true measure of the whole thicknesse of the peece in that place. Thē substracting the diameter of the bore or concauity of the peece from that quotient, note the remainder. Deuide that remaine in two equall partes, the one of those parts is the thicknesse of the met∣tall in that part of the peece so measured.

Example.

I prooued this conclusion with a demy Cannon of sixe inches diameter, in girding the same about with a line hard behind the trunions, and laying the same to an inch rule, it cōtained 44 inches, which summe multiplied by 7, amounted to 308 inches: that summe deuided by 22, my quotient was iust 14. And so many inches was the height of the whole mettall in that part of the peece, out of which quotient I did abate the diameter or bore of the peece being 6 inches, and the remaine was 8 in∣ches, which deuided in 2 equall partes, my quotient being 4 inches, shewed the true thicknesse of mettall

in that part of the peece, being hard behind the trunions towards the breech.

And it is to be noted, that euery peece of Ordinance if it be truly fortified with mettall, ought to containe as much mettall in thicknesse round about, so farre as the chamber where the powder and wad lyeth, as the bullet is in height.