The art of fortification, or architecture militaire as vvell offensiue as defensiue, compiled & set forth, by Samuell Marolois revievved, augmented and corrected by Albert Girard mathematician: & translated out of French into English by Henry Hexam

The 16. Figure. & 5. Plate.

The flanke of this Heptagone, that is, A Fortresse with seuen angles, or Bulwarks, maketh 10 rodd, the distance of the points 72 rodd, and the angle flanked 80 degrees, how many then will the rest make, when as the second flanke is 10 rodd.

SEing that the angle of the Bulwarke makes 80 degrees, and the angle of the Poly∣gone 128:34, 17 the difference divided in the halfe wilbe the angle flanking inte∣riour 24, 17, 18 1/2, the flanck CB 10 rodd, whence the triangle CBG wilbe knowne, & by adding GH giuen to BG, ye shall haue the curtaine 32, 1623, which taken from DP 72 rod, and then take the halfe of the rest, ye shall finde DF, and also DC. CF, for the face DC 21, 8525, & DG 46, 1666, also in the triangle DAE; ye shall haue DE, & consequently EF, or AB. Moreouer ye shall finde DH in the triangle DKH, to be 55, 4345.