FORTIFICATION. 
and about feven feet deep, which rmift be rounded before 
the angles of the redoubt. Make the rampart from four 
feet to nine or ten feet high, according to circuniftances; 
let the parapet be fix or feven feet higher, and let the 
footbank be four feet and a half lower than the crown of 
the parapet. On the fide mod fectire from the enemy 
make a bridge acrofs the ditch, and a paflage through the 
rampart. The breadth of this way fliould be about four 
or five feet, if the defence is to be by nmfketry only ; but 
nine or ten feet if cannon are to 1 e ufed; and in either 
cafe the paflage is to be fhut up by a ftrong barrier or gate. 
But if the redoubt is to be defended by cannon, both the 
rampart and parapet (hould be at lead five or fix feet 
thicker. 
But as it is cudomary for the froops to prefent their 
breads to the parapet, and then fire direct before them, 
there will always be a very condderable l'pace before each 
angle of the work, that will in a great meafure be with¬ 
out any defence. To remedy this defect, it has been pro- 
pofed to round off the inlide of the angles of the parapet, 
and pod three or four men there to defend the angle. But 
this alfo appearing defective, Mr. Clairac has invented 
an ingenious method to make the fire nearly equal in all 
parts; which is done by cutting the infide of the parapet 
into notches, whofe two Tides, of a yard each, are at right 
angles to one another, and make half right angles with 
the Tides of the work; the manner of which, and its de¬ 
fence, is (hewn in the engraving at fig. 23, where the lines 
with dotted ends reprefent the fire given three different 
ways from the fame fide. 
To CONSTRUCT A FLANKED R ED ouBT.~-Having de- 
fcribed the inner figure, as reprefented in the engrav¬ 
ing, at fig. 24, 25, 2'6, where A B is an inner fide of the re¬ 
doubt, fuppofe of about eighteen yards; parallel to 
this figure, at the didance of about five yards from it (or 
more if neceffary), defcribe an outward figure, the Tides 
of which are ED, EF, Sec. fig. 24. Divide each fide, 
as ED, EF, &c. into three equal parts, one of which 
is El, EL, &c.; and in thefe (ides prolonged take DG, 
EH, &c. each equal to one of thofe three parts. From 
the points G, H, Sec. thus found, draw the lines of de¬ 
fence to the angles of the outward figure, as HD, Sec. 
From the points I, L, &c. draw' the Hanks IK, LM, &c. 
perpendicular to the Tides, ED, EF, See. meeting the 
lines of defence in K, M, &c. 
Or, the flanks may be thus drawn. In the line DI, 
fig. 25. continued towards E, take IP equal to twice IE. 
And from P, as a centre with the radius PI, cut the line 
of defence in K, and draw the flank IK. Then to each 
face (HK), flank (KI), and curtain (IG), make a para¬ 
pet of about feven feet thick (or more if necelfary), which 
is exprefled in the plan by lines drawn at that didance on 
the infide of the feveral parts. Leave a proper berm of 
about five feet broad, and make a ditch of about fix yards 
wide, the outer line of which, or counterfcarp, is to be 
parallel to the faces and curtains only. A redoubt thus 
condrudted is much more capable of defence than one 
without flanks: for the curtain IG is well defended by 
the flank IK; and the face HK has confiderable defence 
from the part DG. 
Of REDANS. 
The redan is a fortified line broken into feveral curtains 
and flanks; the defences of the flanks being all diredted 
one way. This is a very good work for the defence of a 
hollow way, a road, a river, or a harbour’s entrance. If 
the defence is intended chiefly for cannon, the didance 
of the flanks from one another fliould not exceed three 
hundred yards, that being about the point-blank flight of 
a mufket fliot. But if the defence is chiefly intended for 
nmfketry, the didance of the flanks may be about fifty 
yards or lefs. In general the diflance of the flanks fliould 
be regulated according to the number of them intended 
to be placed within the length of the line. The length 
of each flank fhould be about eighteen feet, in order to 
admit one gua ; but if more cannon are to be put jn a 
590 
flank, they mud be made proportionally longer. The 
flanks fliould be made about three feet lower than the 
curtains that there may be no danger of the troops poded 
in the faliant angle of one flank being hit by thofe in the 
entering angle of the flank next behind. 
To construct a Redan. —In the front line, fig. 2j» 
take tire equal fpaces AB, AB, Sec. of the length pro- 
pofed for the diflance of the flanks, fuppofe fifty yards; 
draw the perpendiculars AC, BD, of eighteen feet each; 
and draw the faces BC, AD. From the faliant angl.ed 
A, B, draw the flanks AE, BF, at right angles to the 
faces, and the mafler line AEBFAE will be conftrudted. 
Then projedf a rampart, parapet, and foot-bank ; ramps 
in the curtains, an embrafure in each flank, and as many 
in each face as convenient. 
All the preceding matter relates principally to what is 
termed Field Fortification; being employed by con¬ 
tending armies during a campaign, and particularly in the 
invefliture or liege of a regularly fortified garrifon town. 
This depan ment therefore requires to be minutely fludied 
by all officers in the army. 
Of the REGULAR FORTIFICATION of a TOWN* 
or CITY. 
Towns are fortified by furrounding them with the con¬ 
tinuous or connefted works of a rampart, moat, and out- 
vrorks, thence denominated a fortrefs, and the principal 
work or keep, the citadel. 
The rampart of a town is the large bask of earth fur¬ 
rounding the whole place, of a height fufficient to cover 
the habitable parts of the houfes from the fire of an 
enemy ; and of a thlcknefs fufficient to redd the utTnofl 
efforts of his cannon. The rampart at certain diftances, 
within the reach of mulket-ffiot, fliould have works pro¬ 
jecting outwards, either contiguous to the rampart, or de¬ 
tached from it; and thefe projections are to be fo con¬ 
trived, as reciprocally to flank-or defend one another. 
Projecting works contiguous to the ramparts, are the 
bajlions, and thofe detached from it are termed the out- 
works. —In the Fortification Plate II. the names of the 
principal members of the plan of a fortrefs are thus pro¬ 
jected : At fig. 4, HFBMN reprefent the plan of a regu¬ 
lar baflion ; ag the thicknefs of the rampart; ad tlr« 
breadth of the parapet; mmm the moat, ditch, or fofs ; 
aaaa the covered way ; bbbb the glacis. 
Prcjctlion of the principal lints. —The line AB reprefents 
the exterior fide of the polygon, and LA its radius. 
IK the interior dde, and LI its radius. IA the capital, 
CD the normal. GH the curtain, AH the line of de 
fence. GI the demi-gorge, the breadth HN the gorge. 
The line HF reprefents the flank of the baflion, and BF 
the face of the baflion. 
PrcjcElion of the principal angles. —The angle ALB r® 
prelents the angle of the centre. AAB the angle of the 
polygon, or angle of the gorge. EGH the angle of .the 
curtain, or angle of the flank. GEA the angle of the 
Ihoulder. FBM the angle of the baflion, or flanked 
angle. BAH the diminiflied angle. ADB the exterior 
flanking angle, or the angle of the tenail. EHG the ill 
terior flanking angle, apa the angle of the counterfcarp. 
The principal parts of the entire profile of a fortrels, 
are projected through the line PR, fig. 6, delineated at 
the enlarged correfponding figure at the foot of the en. 
graving, on a fcale of twenty-four yards to an inch. 
In this profile, the line A a reprefents the thicknefs of 
the rampart at its bafe. AR the inner Hope, BR the 
inner height, and BC the walk, of the rampart. CD the 
(lope, and DE the top, of the foot-bank. EF the inner 
face or dope, FG the inner top or crown, and GH the 
outer dope or front, of the parapet. HI the face of the 
wall, called the fcarp, IK the breadth of the moat, 
KL the outer wall of the moat, or counterfcarp. 
LM the breadth of the covered way. MN the (lope, and 
NO the top, of the foot-bank. OP the dope of the para¬ 
pet, or inner face of the glacis. PQ the gentle dope, and 
P the head, of the glacis. 
