4 Tables, Lag arit ans. 207

CHAp. Iv.

Contei ning ſome Uſe off righislined Triang les in this Practice N„, FORTIFEICAT ION. e

N che late manner of Fortification the ordinary Care i: 8. That the Angle ef che Bulwark may be either a right Angle ornear unto it. i

2. That this Angle may be defended from the Flank and Cortin on

8 a either Side.

8

3. That the Lines of Defence may not exceed the reach of a Musket,

Vwuhich is ſaid to be twelve ſcore Vards, and thoſe make 720 foot.

4. That the depth of the Flanks and the bredth of the Rampart be ſuf-ficient to xeſiſt battery; and that may be about 100 foot at the ground.

Upon rheſe conſiderations depend the reſt of Lines and Angles: whereof I will ſet down ſome Propoſitions, beginning with that which may,

reſolve che works of others..

Having the Side f 4 Regular Fort, with the length 1 the Gorge, the Elanand the Face of the Bulwark, to End the reſt of the Lines and Angle,

Regular Fort is that, which is made with equal Sides and Angles,A each Bulwark like unto other. a

Suppoſe, that by obſervation or other wiſe, we have found that in a ſquareFort, the Side was 70 foot, the Gorge 140, the Flank 100, and the Face335 In a Pentagonab, Hexagonal, Heptagonal, as in this Table.

Quadr. Pentag. Hexag Heptag. Ocfagen———— F

The Side AB 700 80 90 95%

The Sorge 4D 140 180 190 20 230

Le Han D 10 120 140 150 158be Farrt. E 3352 320 3 420.

And that it were required to find the reſt of the Lines, and the quan-tity of the Angles belonging to each Fort, beginning wich the Quadrate.