Thesaurarium mathematicae, or, The treasury of mathematicks containing variety of usefull practices in arithmetick, geometry, trigonometry, astronomy, geography, navigation and surveying ... to which is annexed a table of 10000 logarithms, log-sines, and log-tangents / by John Taylor.

PROP. I. How to know the different Fortification of a Piece of Ordnance.

In fortifying any Piece of Ordnance there are three degrees observed, as first Legitimate Pieces, which are those that are ordinarily fortified; secondly Bastard Pieces, which are such whose Fortification is lessened; thirdly Double fortified Pieces, or extraordinary Pieces.

The Fortification of any Piece of Ordnance, is accounted by the thickness of the Metal at the Touch-hole, Trunnions, and at the Muzzel, in proportion to the Diameter of the Bore.

The Legitimate Pieces, or the ordinary fortifi∣ed Cannons, have ⅞ at the Touch hole, ⅝ at the Trunnions, and ⅜ at the Muzzel of the thickness of the bore, in thickness of Metal. Bastard Cannons, or lesned Cannons, have ¾ at their Touch-hole, or 12/16, and 9/16 at their Trunnions, and 7/16 at their Muzzel: the Double fortified Cannons have full one Diameter of the Bore in thickness of Me∣tal at the Touch-hole, and 11/16 at the Trunnions; and 7/16 at their Muzzel. Now all double fortified Culverins, &c. are 1 ⅛ at the Touch-hole, 15/16 at the Trunnions, and 9/16 at the Muzzel, and the Ordi∣nary fortified Culverins, are fortified every way as double fortified Cannons, and lesned Culverins as Ordinary Cannons in all respects.