Encyclopaedia Britannica, or, a Dictionary of arts, sciences, and miscellaneous literature : enlarged and improved. Illustrated with nearly six hundred engravings > Volume 9, FOR-GOT

II. FORTIFICATION.
Of
rortlii'T Sect. II. Of Irregular Fortification.
■_ * ' ' The moil eilential principle in fortification confifts
Plate iii making all the fronts of a place equally ilrong, fo
CCXXIII. that the enemy may find no advantage in attacking
either of the iides. This can happen no otherwife in
a regular fortification fituated in a plain or even ground :
but as there are but few places which are not irregular
either in their works or fituations, and the nature of
the ground may be fuch as makes it impraflicable to
build them regular without too great expence } it is fo
much the more necefl’ary to fhow in what confilts the
llrength or weaknefs of a town irregularly fortified, fo
that the weakeft part may be made ftronger by addi¬
tional outworks ; as likewife, if fuch a place is to be
attacked, to know which is the llrongell or weakell
part. .
I. CotiflruBion of an Irregular F lace Jituated in an open
country.
If the place to be fortified is an old town cnclofed by
a wall or rampart, as it moll frequently happens, the
engineer is to cpnfider well all tire different cireum-
flances of the figure, fituation, and nature of the ground j
and to regulate his plan accordingly, fo as to avoid the
difad vantages, and gain all the advantages poffible:
he ftiould examine, whether by cutting off fome parts
of the old wall or rampart, and taking in fome ground,
the place can be reduced into a regular figure, or
nearly fo-, for if that can be done without increafing
the expence confiderably, it fhould by no means be
omitted. Old towns have often towers placed from
dillance tp diftance, as Douay, Tournay, and many
other places, which' are generally made ufe of, and
mended when it may be done. If there is a rampart
without ballions or towers, it mull be well confidered
whether ballions may not be added, or if it is not bet¬
ter to make only fome outworks : if the ditch about
this rampart is not too wide and deep, it would be ad¬
vantageous to make detached baftions ; otherwife rave¬
lins and counterguards muff be conllrufled. Special
care muff be taken to make all the fides of the polygon
as nearly equal as poffible, and that the length of the
lines of defence do not exceed the reach of mufket-lhot;
but if that cannot be done, thofe fides which are on
the narrow-eft part ftiould be made the longeft.
If it fhould happen' that fome of the fides are inae-
ceflible or of very difficult approach, either on account
of fome precipice, marftiy ground, or inundation, they
may be made much longer than the others which are
of cafy accefs, and the flanks need not be fo l^rge as
the reft y by doing fo, there will be fome expences fa-
ved, which may be ufed in making the other fides
ftronger by adding more outw-orks.
There are few fituatioas but what are more advan¬
tageous in fome parts than in others; it is therefore
the bufmefs of an engineer to diftinguiih them, and to
render thofe fides ftrong by art which arc not fo by
nature.
If the fituation is kw and watery, lunettes or tenail-
lons, and fuch other fmall outworks, fhould be conftruc-
ted ; becaufe they are not of any great expence, and
may make a very good defence. But if one fide of the
place only is low-, and running water is to be had, a fe-
cond ditch and covert-w-ay with lunettes may be made,
by obferving, that if the firlt glacis is made to Hope,
fo as to become even with the level of the water in the
fecond ditch ; or if the water can be fuelled by means
of dikes or iluices, fo as to overflow the belt part of
. the firft glacis, it Ihould be done : for by fo doing
thefe works will be able to make a very good defence,
fince the befiegers will find it a diflicult matter to lodge
themfelves upon this glacis ; which cannot be done but
within a few toifes of the firft covert-way, where the
befieged are ready to receive them, and to deltroy their
works with great advantage ; whereas the enemv can¬
not fupport their workmen but from the fecond covert-
Avay, w hich is too far off to be of any great fervice to
them.
But if the fituation is of a dry nature, without any
w-ater upon it, caponiers fl^ould be made in the great
ditch, from the curtains to the ravelin, and batteries
raifed in the entrance of the ditch before the ravelin,
whofe parapet mutt Hope oft" into a glacis fo as to af¬
ford no cover for the enemy behind them. Arrow s and
detached redoubts are likewife /very proper to be uled
in fuch a cafe ; and fometimes horn or crownworks, if
it Ihould be thought convenient: but thele works
Ihould never be conftru6ted without an ablblute necef-
fity, either to occupy a fpot of ground which might
be advantageous to the enemy, or to cover lome gate
or entrance into the town ; for they are of great ex¬
pence, and their defence feeras not to be anfwerable
to it.
Moft of the places in Flanders are fortified with
hornworks, fuch as Ypres, Tournay, Lille, and o-
thers.
If the place to be fortified is'new, and the fitualion
will not admit of a regular eonltruclion, particular
care muft be taken in c hoofing fuch a Ipot of ground as
is moft advantageous, and leatt liable to any difadvan-
tages either in the building or in the maintaining of it.
All hills or rifing grounds ihould be avoided, which
might command any part of the works ; marlhy grounds,
becaufe fuch fituations are unwholefome ; or lakes and
Handing waters for the fame reafon, excepting a lake
is or may be made navigable. Good water Ihould be
had either within the place or near it, for it is abfolute-
ly neceffary for men and cattle : the air Ihould be
wholefome ; otherwife the continual ficknefs that may
reign in fuch a place might prevent people to come and
live in it, and the garrifon would not be in a condition
to defend themfelves as they ought to do. In ftiort, all
the different circumftances attending fuch an undertak¬
ing fliould be matun ly confidered before a refolution is
taken to fortify any place.
When a fituation is fixed upon, the next thing to be
confidered is the bignefs of the town and the number
of. its outworks ; which muft abfolutely depend upon
the confequence fuch a place is of to a nation. If it is
only to guard a pafs or entrance into a country, it
need not be fo large : but if it is to be a place either to
promote or to proteft trade, it Ihould be large and com¬
modious ; the ftreets ftiould be wide, and the buildings
regular and convenient. As to what regards the forti¬
fication, its conftrudion fhould depend on the nature
of the fituation, and the number of works, on the funds
or expence a prince or a nation will be at; which,
however, ought to be according to the benefit arifing
from
3X
Of
Irregular
Fori if ca¬
tion.
‘»
Plate
CCXXIII.