FORTIFICATION. 
their use more common, especially where 
the ground favours their command of all 
the other works. 
Although we have, in tracing the defile- 
ment of the. ramparts, from the point fl>, to 
the centre of the polygon E, laid it down 
as a general rule, that the ascent of the 
works should assimilate to that line ; yet 
in such very spacious defences as crown- 
works sometimes are, (for their area is 
occasionally equal to a third of that within 
the interior line of the polygon,) some ex- 
ceptions will take place ; especially when 
the ravelines opposite to the faces of the 
crown-work, are defended by still farther 
advanced out- works : then the angle of de- 
filement would be so acute, from the terre- 
pleine, or horizon, as to cause scarce any 
difference between the heights of the ra- 
velines, and of the bastions of the crown- 
work : a matter of obvious impropriety. 
Hence, it is often necessary to give the 
ramparts of a crown- work, rather more height 
than the line of defilement might allow ; 
raising the raveline and its intenchments 
suitably, and making cavaliers, as instanced 
in the bastion C, of the crown- work, on the 
solid bastions 3 and 4, so as to command 
the whole of the crown-work completely. 
A moineau, or flat bastion, of similar height 
with the cavaliers, may be made in the cen- 
tre of the curtain u v, for the same purpose. 
Cavaliers are of singular use on many 
other occasions, to which their form should 
be accommodated ; that in the bastion c of 
the crown-work, is, from its shape, termed 
a horseshoe ; the flatness of its front is ap- 
plicable to the situation it there holds, be- 
cause it opposes a direct fire towards the 
point O; but its circular tendency gives 
its front a bias towards the inner parts of 
. the faces of the ravelines, while its flanks 
present a direct fire into the ravelines them- 
selves, and give an oblique fire into the op- 
posite ditches, whereby the assault of 
breaches in the saliant angles of the demi- 
bastions b b, would become very hazardous. 
The proportions of a crown-work must 
depend greatly on the purposes for which 
it is erected, but whatever be its object, the 
whole of its defences should be commanded 
by the works of the principal in so com- 
plete a manner, that no part, whatever, 
should offer an asylum to the enemy, after 
carrying it ; and consequently, that none 
of its batteries should be able to play into 
any other of the defences. For the loss of 
so large a limb, and of the many service- 
able cannon, platforms, &c. which, in such 
case are invariably, and actively employed 
against the body of the place, is a very se- 
rious concern, and requires the utmost ex- 
ertion to oppose even for a time. On this 
account it is highly necessary to have mines 
under all those parts which can prove ser- 
viceable in the smallest degree to the 
enemy, and to blow them up whenever a 
favourable moment may present itself. 
From what has been stated as to the 
purposes of crown-works, it will be seen, 
by reference to that laid down in the. plate, 
that much attention is requisite to give them 
every defensive property, while on the 
other hand they should prove of little value 
to a successful assailant. The only work 
in our plan affected by such a circumstance, 
would be, that the counterguard 7 would be 
untenable as a battery, though it might re- 
tain some small utility as a casemate. But 
by mining all the inner part of the flank, 
which commands the counterguard, even 
that evil would be lessened ;■ if, however, 
an enemy shotdd be able to carry the rave- 
line N, and to maintain his ground therein, 
notwithstanding the tremendous fires from 
the faces of the bastions 3 and 4, and from 
the curtain u v, (all of them direct) but little 
hope could remain of a successful resistance, 
and the counterguard would be, compara- 
tively, no sacrifice. We, however, see from 
this, that a tenaille on the lines of defence 
t, u, w, as shewn at P, between the bastions % 
and 3, must prove highly serviceable, es- 
pecially if mounting such heavy metal as 
would destroy any works thrown up in the 
raveline N. 
The intrencliments f f, cut the ramparts 
of the flanks of the crown-work through 
all but the revetement, and they are carried 
as far forward as possible, so as barely to be 
flanked by a barbet battery in the saliant 
angle of the raveline, that the bastions of 
the crown-work may be perfectly com- 
manded by musquetry. The cavalier in C, 
is supposed to be mined and destroyed, 
else it would prove very disadvantageous 
to the defence of the raveline, which it 
would partly command. 
We have already observed, that many 
out-works might be shewn in addition to 
those given to the faces of the crown-work, 
such as lunettes, tenailles, tenaillons, fieches, 
advanced lunettes, redoubts, bonnets, &c. 
but we apprehend the reader will, from the 
foregoing details, and the plate to which 
they refer, be able to supply to his imagina- 
tion, the almost endless continuation of out- 
works, which thejimits we are compelled 
