THE DECYFERING OF A CANNON Bullet, or any other peece by letters, as followeth.
BEsides this manner abouesaid, by fitting your bullets out of the Magazin, for the Calibres and bores of any peece of ord∣nance, by the helpe of the mailes, the Caeron bullet marked H. shewes you also another way to fitt the Calibre of a peece of ordnance, with a right bullet, by giuing it the re∣quisite vent. As for example, take the iust Diamiter of the mouth of your peece with a paire of straight Compasses, and then devide the ouertur thereof into two equall parts, and draw from the Center the circle marked B. A. and E. whose Center also is noted to be D. which is the forme and Circumference of your peeces mouth orbore, Then set the two points of your compasse vpon the points A. and B. in drawing one after another, the crossoe- lines vnder C. from whence you shall draw a line parpendicular to D. downe to the bottome of the circle marked E. and from thence another line to the point A. Then set one of the points of your compasse vpon the point E. and the other vpon the line which you haue drawne from thence towards A. and marke well the point which the circle makes thereof from F. where letting rest the point of your Compasse, you shall raise the other which was in the point E. vpon the first line perpendicular, which you haue made from the crosse-line at C. by the Center to D. where the point C. will shew you how much lesse the bullet must be. Then the Dyamiter or Calibre of the mouth of your peece, for giuing it the necessary vent, so that putting the one point of your compasse upon the center D. and draw in the other which is sett vpon the edge of the circumference and Large∣nesse of the peeces mouth O. to the point G. and so in making an other circle the Dyamiter thereof will be the iust and requisite calibre and Circumference of your bullet, and which will fit thebore of a whole Canon, or any other peece which you shall desire.
There is a third way found out byskillfull Canoniers, by abating the twentieth part of the Calibre of your peece in the circumference thereof, to the bullet which with a sufficient abatement and vent for your peece, which rule is easily found out by takeing the iust Dya∣miter of the mouth of your peece.