FORTIFICATION. 
different works with regard to the trace, the next im- 
( mi relief. This is done’ 
i 
f 
| 
8, 
~ 
is 
EB 
a5 
r 
i 
H 
iu 
4 
‘ 
: 
£ 
e 
_ To find the height of the saliant angle of the bas- 
tion. 
As the distance between the saliant angle of the 
bastion and the saliant angle of the place of 
arms 
To the distance between the angle of the shoulder 
eae reys third parallel before the demi- 
_ une :: 
So is the height of the glacis before the place of 
arms + 3 feet: 
To the height of the crest of the parapet at the sa- 
liant angle. 
The enemy’s third trench or parallel is generally at 
such a distance as to touch the exterior side of the 
glacis opposite the bastions and ravelins. 
aqie determine the height of the angle of the shou!- 
of the is: 
To the distance between the angle of the shoulder 
and the third in the ion of the sa- 
liant angle of the demi-lune : : 
So is the height of the glacis before the saliant of 
the demi-lune + 2 feet : 
To the height of the angle of the shoulder. 
eae nma: proportion thee and in the latter 
two feet, are od tothe hadche eee er ee 
glacis, that the fire of the body of the place may not 
injure the men in the covered way. The same is done 
in every other work, 
curtain is a s 
' of the flanks. It may be observed, however, in general, 
495 
The command of the faces being determined, that of Permanent 
the flanks is made the same. 
traight line joining the crest of the angles 
that two or three feet, according to circumstances, are 
frequently added to the command determined by the 
preceding rules. 
To determine the command of the demi-lune at its of the gorge 
The command of the Fortifica- 
tions. 
gorge, or the extremity of its face on the counterscarpe of the demi- 
of 
great ditch. 
As the distance between the saliant angle of the 
place of arms and the third parallel : Saute 
To the distance between the extremity of the 
'_ demi-lune at its gorge, and the same paral- 
‘lel:: j 
So is the command of the glacis before the place 
of arms + 3 feet: 
To the height of the demi-lune at its gorge. 
lune. 
To determine the command of the saliant of the of the sa- 
demi-lune. 
way to the third el: 
To the distance between the saliant of the demi- 
lune and the same lel: : 
So is the command of the glacis before the saliant 
+ three feet : 
To the height of the saliant of the demi-lune. 
When the command of the demi-lune is determined 
by this rule, that of the enceinte, as formerly mention- 
ed, requires to have two or three feet more than the 
above rules give. The command of the reduit within 
the ravelin ought to be three feet. 
The p' methods of determining the profile 
of a place, will in ordinary cases give nearly the fol- 
lowing heights: For the saliant angle of the bastion 
174 feet, and the shoulder 21 feet ; for the gorge of 
the demi-lune about 17} feet, and for the saliant angle 
144. The interior side, or command of the glacis, as 
has been already stated, is 7} feet above the covered 
way, and its declivity towards the field ought to be 
1 foot in 24, If the declivity be , it covers the 
enemy's trench or parallel; and if less, the covered way 
becomes 
liant of the 
As the distance from the saliant of the covered demi-lune. 
The revetement of the rampart ought to be equal in Revete- 
height to the crest of the glacis, and at least 25 feet ments. 
above the bottom of the ditch. This gives 18 feet for 
the d of the ditch below the covered way. Some- 
times the revetement is not carried so high as the crest 
of the glacis, and the above is planted with 
thorns, or defended by peliidee This is called a 
demi-revetement ; but it has the disadvantage of assist- 
ing the enemy in the escalade, and therefore ought not 
to be ado ded adios the ditch can be inundated with 
water. For the same reason, the revetement should 
not terminate at top, as it often does, with a derme or 
round way, which serves only to afford the enemy 
greater facility in fixing their scaling ladders. The 
thickness of the wall of the revetement should be at 
least 4 feet at top, and 5 if the height exceed 12 feet. 
At bottom, the thickness ought to be one-sixth of the 
height. To en the revetement, counterforis or 
buttresses of solid masonry, from $ to 33 feet thick, 
are built behind it, at the distance of from 10 to 15 feet 
between centre and centre, which support a consider- 
able part of the pressure of the rampart. When the 
ditch is dry, a row of palisadoes is sometimes construct 
ed in the bottom along the centre, 
4 
