The new method of fortification, as practised by Monsieur de Vauban, Engineer General of France with an explication of all terms appertaining to that art / made English.

CHAP. XII. The manner of Fortifying an irregular Place, where there is nothing but the Field.

1. HAving the Plane of the irregular Place, divide each ex∣ter or side into two equ••l parts; and from the Middle let fall a Perpendicular••

2. Upon each exterior side draw an ••••osceles Triangle of 480 Fathoms.

3. Place upon these Triangles all the Parts and Distances which you make use of in a regular Fortific••tion, and take the Distances across to put them upon he parts of your irre∣gular Plane•• For Example; if an irregular Pentago•• be ••o be fortified, I take 180 Fathoms an•• I m••ke ••pon each exterior side an ••soscel••s Triangle, ABC. Then I ••ak•• 2•• Fathoms, which I put upon the Triangle ABC, as CDE; of which the length DE, shall be the true Length for the Pe••pendicular of the Line AB: Which done, I put 50 Fathoms upon the same Triangle, as CFG the Length FG, sh••ll be the just dista••ce ••or the Face of my Work. After this, I put again 38 Fathoms 3 Feet upon the Triangle; and the distance taken across HI, will give me the true Length for my Complement of the Line of Defe••ce. Las••ly, I join the Flanks and the Curtains together, as i•• a

[illustration]

The Plan of a Horn work before the Bastion of a Square.

[illustration]

The Draught of a Horn-work with Shoulders.

[illustration]

a Horn-work with a Crown before it.

[illustration]

A draught of a Square with a Crown Work before the Courtin. Fig: 11

[illustration]

A Pentagone or Work of five Bastions. Fig: XVI.

[illustration]

A Draught of a Pen¦tagone or five sided Figure with Tenailles within the Ditch. Fig: 16.

regular. After which I divide the Flank into 3 equal parts; I draw the Brisure as usually, and retain one of the 3 parts of the divided Flank for the Orillon, and the two o∣thers for the hollow Tower. See the Plate T. Fig. 38.