FORTIFICATION 
bastions, were provided with ravelins, horn- 
works, and outworks of all kinds, so as to re- 
sist the violence of cannon and mortar bat- 
teries ; and defy, at least for a time, the ef- 
forts of the besiegers, provided with all the 
various implements of modern warfare. 
Fortification is either regular or irregular. 
The regular is that built in a polygon, the 
sides and angles of which are all equal, be- 
ing commonly about a musket-shot from each 
other. Irregular fortification, on the con- 
trary, is where the sides and angles are not 
uniform, equidistant, or equal. 
I. Of regular Fortification. 
Authors in general agree as to the form, 
but they differ in respect to the construction 
of t he parts. The chief of those who have 
written on this art, are Pagan, Blondel, Vau- 
ban. Co.-horn, Scheiter, and Muller: in ad- 
dition to these the names of Robins, Belidor, 
Folard, le Blond, marshal Saxe, Tielke, and 
Bel air, ought also to be enumerated, as they 
have greatly contributed to the general know- 
ledge of the science. 
It must be constantly recollected by every 
engineer, that his views are not to be con- 
fined to the mere art of fortification. lie 
must be able to take advantage of natural 
strength and position. Chains of mountains 
and streams of water, together with the in- 
li nence of climate, should constitute a part 
of the natural system to which he should di- 
rect his application. 
According to count Pagan, fortification 
consists of three different sorts, viz. the great, 
the mean, and the little, the principal dimen- 
sion; of which art: contained in the following 
T A B L E. 
For all 
other 
Polygons 
o 
o 
50 
CM 
1 
CO 
CM 
1 
o 
'-0 
f 
CM 
| For 
Squares. 
o 
CM 
7 
GO 
uo 
i 
CO 
tp 
’O 
1 
to 
d 
cZ 
o 
% 
For all 
other j 
Polygons 
iso j 
O 
'O 
CM 
1 
o 
*o 
to 
1 
CO 
CM 
1 
The 
u § 
O rd 
r JO 
180 
O'! 
55 
I -61 
1 
'O 
CM 
For all 
other 
Polygons 
c 
o 
CN 
so 
GO 
CM 
1 - 
CM 
70-5 
141-2 
.2 
For 
Squares. 
200 
t N - 
CM 
GO 
CM 
01 
CM 
1 
CO 
141-4 
ni 
<L> 
u 
be 
2 
Exterior side 
| The perpendicular 
The face 
The flank - 
The curtin - - 
The line of defence 
Blondel fortifies will iin the given polygon: 
he establishes two sorts of fortification the 
great one, whose exterior side is 200 toises, 
and the lesser one, 170 ; because he will not 
have the line of defence exceed 140 (ones, 
which is the greatest musket-shot, nor less 
than 1 20 toises, not to increase the number 
of bastions. He begins by the diminishing 
angle, which maybe found by taking 90 de- 
grees from the angle of the polygon, and by 
adding 15 degrees to the third of the re- 
mainder. 
Vauban’s method is divided into little, 
mean, and great; the little is chiefly used m 
the construction of citadels; the mean, in 
that of all sorts of towns ; and the great, in 
particular cases only. 
TABLE. 
In the first vertical column are the num- 
bers expressing the lengths of the exterior 
sides from 80 to 260. 
In the second, the perpendiculars answer- 
ing to these sides. 
In the third, the lengths of the faces of the 
bastions ; and in the fourth, the lengths of the 
capitals of the ravelins. 
Belidor’s method is divided aiso info little, 
mean, and great ; and in all three the exte- 
rior side is 200 toises ; the perpendicular of 
the little is 50, that of the mean 55, and the 
great 40 ; the faces of the first 70, the se- 
cond 70, and the third 55 toises. 
Scheiter’s method is divided into the great, 
mean, and small sort. The exterior side of 
the polygon for the great sort is 200 toises, 
the mean sort 180, and the small l60. The 
line of defence in the first is 14'0 toises, the 
second 130, and the third 120. This line is 
always razant. All the other lines are fixed 
at the same length for all polygons, whose 
structure chiefly depends upon the know- 
ledge of the exterior side, of the capital, or 
of the flanked angle, the rest being easily 
finished. 
;o.> 
Errard, of Bois-le-Duc, who was employ- 
ed by Henry IV. and was l he first that laid 
down rules in France respecting the best me- 
thod, of fortifying a place so as to cover its 
flank, constructs that flank perpendicular to 
the face of the bastion ; blit by endeavouring 
to cover it etfectuady, he makes the gorges 
too exiguous, the embrazures too oblique, 
and leaves the ditch almost defenceless. 
The chevalier de Yille, who succeeded Er- 
rard, draws the flank line perpendicular to 
the enrtin ; but here again the embrasures 
are too oblique, especially in the polygons, 
and the ditch is necessarily ill guarded. 
This engineer’s method of fortifying is styled 
by most authors, t he French method. His 
favourite maxim is, to make the flank angle 
straight, and the Hank equal to the demi- 
gorge. 
Count Pagan makes the flank perpendi- 
cular to the line of defence, which method 
seems to agree perfectly with this maxim, 
because by that means the flank so raised co- 
vers as much as possible the face of the oppo- 
site bastion ; but notwithstanding this appa- 
rent advantage, the flank becomes too small, 
and is too much exposed to the enemy’s bat- 
teries. T his engineer acquired great reputa- 
tion during the several sieges which he assist- 
ed in conducting under Louis XIII. FI is 
system has been improved upon by Alain 
Marrison Mallet, and his construction in for- 
tification is to this day esteemed the most 
perfect. It differs very little from marshal 
Vauban’s first system. Count Pagan lias 
pointed out the method of building casemates 
in a manner peculiar to himself. 
Marshal Vauban has judiciously steered 
between these different methods. He has 
drawn his flank in such a manner, that it does 
not stand too much exposed, nor does its 
collateral line of defence extend loo far fmm 
the direct line of defence. He has effected 
this bv lengthening out his flank, and giving 
it a circular form. 
It cajnnot be. disputed that large and 
