[Fig. 5]. The hexagonal redoubt.
Describe a circle, radius 30 yards, and construct a hexagon within it (vide [Practical Geometry]); the sides of which form the crest of the parapet of the work.
[Fig. 6]. The circular redoubt.
Describe a circle, radius 30 yards, which will form the crest of the parapet of the redoubt.
[Fig. 7]. The star fort, with six points.
Construct an equilateral triangle, and divide each side, 75 yards, into three equal parts, form also an equilateral triangle on the central portion of each side, 25 yards, and the crest of the parapet of the fort will be traced.
[Fig. 8]. The star fort, with eight points.
Construct a square: divide each side, 60 yards, into three equal parts, and on the central portion, 20 yards, describe an equilateral triangle: the periphery of the fort will thus be obtained.
[Fig. 9]. The field fort, with bastions, and half bastions.
Construct a square; from the centre of each side, 120 yards, drop a perpendicular equal to one-eighth of the side, through the extremity of which, from the angles of the square, draw the lines of defence; make the faces of the bastions, and half bastions, two-sevenths of the exterior side, and draw the flanks perpendicular to their respective lines of defence.