Diagrams of various fortificationsFIELD FORTIFICATION.J. W. Lowry, sc.
FIELD FORTIFICATION.J. W. Lowry, sc.
FIELD FORTIFICATION.
J. W. Lowry, sc.
Fig. 10. The bridge head, or tête du pont.
Construct a redan, base 50 yards, perpendicular 30 yards, at an appropriate distance from the bridge, 50 yards; draw flanks, 20 yards, perpendicular to the faces, and from their termination draw lines to the river parallel to the capital of the work. To strengthen the defence of the tête du pont, construct a flèche, faces 20 yards each, and 10 yards in front of the bridge, 4 yards wide.
In the construction of bridge heads, the foregoing Figures may be employed when expedient; the simplest form, the redan, being for light bridges, and the more perfect defence, the bastioned front, or fronts, for bridges of material consequence.
Fig. 11, 12, 13.Lines.—VidePlate.
Fig. 11.Construct a redan, base 40 yards, perpendicular 30 yards; which join by a curtain 100 yards, to a queue d’aronde.
Fig. 12.Side of square, 35 yards, and lines drawn from summit to points on the curtains 10 yards. To increase the defence of the next curtain, 100 yards, bisect it by a perpendicular, 15 yards, and draw the two faces. Lengthen the lines by cremaillères.
Fig. 13.Base 100 yards; crochet, base 5 yards; perpendicular 20 yards.
Lines, continuous, are formed by a modification of redans, lunettes, curtains, &c., dependent on the nature of the ground, and the means of defence.
Lines, with intervals, are formed by detached redans, lunettes, &c., within range of each other; the rear works flanking those in front.
Bridges, and passagesinto field works are from 6 feet, to 12 feet wide, according to the requirements.
Traversesare placed about 9 feet from the slope of the banquette, their length being so regulated as to exclude from the view of the enemy the interior of the field work.
The nature, and form of the field work, or lines, required for the defence of a post, &c., &c., having been determined, the perimeter may be laid down, in conformity to the construction detailed in the foregoing figures: after which the requisite dimensions of the parapet, ditch, &c., (dependent, of course, on the nature of the enemy’s ordnance) must be taken into consideration, and the quantity of earthwork computed by theRules,page 245, or by those inPractical Geometry. The following Table will, however, in many cases be found useful; and, by a judicious adaptation of it, much time may be saved in the computation, and construction of field works.