FORTIFICATION. 
before the baftion ; and the outline of the counterguard 
will be determined; the inner boundary being the coun- 
terfcarp of the grand fofs. Put a rampart about eighteen 
yards broad, with a parapet of fix yards, and annex the 
ramps, and a bai bet if neceffary : alfo make a tofs of 
twenty-four yards in breadth, the counterfcarp being pa¬ 
rallel to the faces. The counterguard feems to be, next 
to the ravelin, one of the moft-ufeful outworks; for it 
occupies but little ground, is of no great expence, covers 
the faces of the baftion fo effectually that they cannot be 
battered in breach, until the enemy has made himfelf 
matter of this work; and when he has it, he will meet 
with difficulties enough in finding earth to cover himfelf 
and eredt his batteries; and mutt therefore be at confide- 
rable trouble and length of time in bringing it from be¬ 
yond the fofs, while he is expofed to the fire of the faces 
of the neighbouring ravelins ; which, with the flanks of 
the baftions, are the defences of the counterguard. 
The tenaillon is compofed of a ravelin, and two detached 
■lunettes, which partly or wholly cover the faces of the 
ravelin from an enemy’s direft fire. When the detached 
works cover only the lower part of the faces of the rave¬ 
lin, they are called fmall Lunettes ; but when they cover 
the whole faces, they are called great lunettes, and thus 
combined they form the tenaillon. 
To conjlruEl the tenaillon. —Having defcribed the ravelin 
and its fofs, the counterfcarp of which is rt, fig. 19 ; in 
the face (^'continued, take tv, equal to about fixty yards, 
and on the counterfcarp of the grand fofs take rs , equal 
to twenty-five or fifty yards; then drawing sv, the figure 
defcribed by rsvt, is the great lunette-, to which a rampart, 
parapet, and ramps, are to be annexed againft its faces 
■tv, and branches vs, of the fame kind with thofe in the 
ravelin. A lunette may be confiderably ftrengthened by 
making acrofs its middle, at A, a retrenchment, confift- 
ing of a rampart, parapet, and a fofs, about fix or eight 
yards broad, and feven or eight feet deep ; the parapet 
being drawn at right angles to the counterfcarp of the 
ravelin againft the middle of its face ; and the ditch of 
the retrenchment communicating with that of the rave¬ 
lin. A tenaillon is a work capable of affording great de¬ 
fence to the belieged, as was evinced at the fiege of Lifie, 
where the befiegers were twice or thrice driven out of a 
tenaillon they had taken and retaken. 
The horn-work is a fpecies of fortification compofed of 
two long Tides, called branches, tending toward the town, 
and of a front formed by a curtain between two half- 
baftions. It is fometimes placed before a baftion, but 
oftener againft a curtain. 
To conJl\'u£l a horn-work before a curtain. —In a line drawn 
from O, fig. 20, the, angle of the counterfcarp, at right 
angles to the curtain, take OC equal to about 250 yards; 
through C draw A A at right angles to OC, and make 
C A, CA, each equal to half OC, fo AA is equal to 
OC. Take the normal CD equal to one-fixth of A A, 
through D draw the lines of defence A I; make the faces 
A B equal to one-half AD ; transfer th.e diftance B B from 
B to I the line of defence, draw the flanks BI and cur¬ 
tain I I, and draw the branches A Q^toward fome point 
in the face of the baftion, about ten yards from the angle 
of the fhoulder. Againft the faces, flanks, curtain, and 
branches, put a ramparr and parapet as in the ravelins; 
make a fofs of twenty-four yards in breadth before the 
flanked angles A, the counterfcarp of the fofs in the front 
being directed toward B, the angle of the (houlder, and 
the reft drawn parallel to the branches. A fmall ravelin 
is ufually put before the curtain of a horn-work, for the 
fame ufes as that before the curtain of the town. Make 
the capital CP about fixty yards, draw the faces as in the 
large ravelins, and make a fofs about lixteen yards wide, 
the counterfcarp of which is parallel to the faces of the 
ravelin, which are to be furniihed with a rampart and 
parapet. 
Retrenchments are fometimes made in the horn-work, 
as in the great lunette, and for the fame reafon, namely, 
Vol.VII. N0.453. 
605 
to increafe the difficulties of an enemy in a fiege. Aifo 
a ravelin with its fofs is made before the curtain ot the 
town, independent of the horn-work which it commands. 
The fortification called a crown-work, the front ot which 
confifts of a whole baftion, two half-baftions, and two 
curtains, is bounded on the Tides by two long branches, 
directed toward tire town. This work conlifts of two 
horn-works connefted together, by their branches being 
put fide to fide. Horn-works and crown-works are chiefly 
ufed toinclofe fome rifing or hollow ground, ora fuburb. 
Of the Covered-way and Glacis. —When all the 
intended outworks are completed, the covered-way and 
glacis are to be projedted parallel to the counterfcarps of 
the fofles; and a foot-bank is to range quite round the 
covered-way, at the foot of its parapet. The top of this 
foot-bank fliould be at leaft four feet broad, that there 
may be convenient room for the troops to ftand on, after 
the pallifades are planted, a row of them being always to 
run quite round the covered-way. The manner of fetting 
them, as recommended by the celebrated marfhal Vauban, 
is to fix the pallifades on the upper foot-bank about four¬ 
teen inches aiftant from the foot of the parapet, funk in 
the ground at leaft three feet, and their top on a level 
with the head or creft of the glacis. Pallifades thus 
placed are not expofed to the cannon of the befiegers ; 
the mod they can do will be only to brufli their points; 
neither can they be eafily fcaled by the troops commanded 
to the attack of the covered-way, nor readily cut down ; 
and their diftance from the parapet leaves a fpace fuffi- 
cient for men to go along to repair any diforder. 
Places of arms, in the covered-way, are recedes made 
at the entering and faliant angles, confiderably larger than 
the ftreet of the covered-way, and formed by turning the 
head of the glacis into two faces projecting toward the 
country; thofe at the faliant angles are formed by the 
roundings of the counterfcarp ; but thofe at the entering 
angles are thus conftruCted : In the head of the glacis take 
the gorges CO, C O, fig. 3, from twenty to thirty yards ; 
draw the faces Ot, Ot, fo that the angles to a be between 
ninety and one-hundred degrees; and parallel to thofe 
faces draw a glacis of about fifty yards. The faces Of 
of the entering places of arms fhould not make angles 
greater than one hundred degrees with the branches of 
the covered-way Os, becaufe thofe branches could not 
then be defended fo well by the mnfketry, as when their 
fhot is delivered direftly along the glacis, nearly parallel 
to the branches, which can only be done when the de¬ 
fences are nearly at right angles to the places defended. 
Some engineers have advifed to round all the faliant 
angles of the places of arms, becaufe thofe angles can 
then be defended by a greater number of men : perhaps 
there might be conliderable advantage in notching the 
faces, fomewhat like a redan, as mentioned above. 
The great Coehorn was fo confcious of the advantage 
of places of arms at the entering angles for the defence 
of the covered-way, that he was very particular in their 
confirmation. They are projected as follows: Take the 
gorges ab , ab, fig. 21, about forty-five yards, and the faces 
be, be, about fifty or (ixty yards. At ten yards diftance 
from the faces, draw the firft lunette A, with a ditch be¬ 
fore its faces, both together being about twelve yards 
broad, its ends terminated by the line ab. Within this, 
at ten yards diftance, draw a iecond lunette B, about five 
yards broad, its ends ftretching half the breadth of the 
covered-way. Behind the ends of each lunette, at the 
diftance of three yards, put a traverfe of about five yards 
thick, reaching from the counterfcarp about three yards 
farther than the ends of tiie lunette. And about the 
angle of the counterfcarp.make a fkreen of fix yards in 
each face and gorge ; which ikreen is to be of brick-work, 
with loop-holes for the mufketry. 
Of traverfes in the covered-way .—When the befiegers have 
pulhed on their approaches fo far as to be within thirty 
or forty yards of the head of the glacis, it will be in their 
power to rake the covered-way from fome of their battc- 
7 P ries; 
