y. 
FORTIFICATION. 
to draw around this branch of science pre- 
clude us from enlarging upon. 
The bonnet mentioned in the preceding 
paragraph, is nothing more than an angle 
made parallel to a raveline, and not far re- 
moved from it, so that the faces of the lat- 
ter command the faces of the bonnet. This 
out-work comes down to the lunettes, by 
which it is flanked. 
We now have to treat of those important 
parts the glacis, and the covert-way. The 
former is a gradual slope, commencing 
at a distance from the exterior of the out- 
works, seldom less than fifty yards, and 
when within five toises of the ditch, stops 
abruptly, occasioning a sudden fall, never 
less than seven, nor should it be more than 
nine, feet. Here it is supported by a reve- 
tement, and is partly met by a banquette of 
turfed soil, which is raised high enough to 
come within four feet and a half of the crest, 
or highest part of the glacis. At the foot 
of the revetement, at such distance as may 
prevent an enemy jumping over, say from 
two to three feet off, a row of palisades is 
fixed ; these are strong pales nine feet in 
length, of which one third is buried in the 
banquette, while the long horizontal rails 
to which the palisades are firmly railed, are 
at every ten feet morticed into square ports. 
The lower rails are one foot from the ban- 
quette, and the upper ones are just level 
with the crest of the glacis, so that the 
soldiers may fire through the top intervals 
between the pales, resting their pieces on 
the upper rail. 
The primary defences are in the covert- 
way, but they are only for musquetry ; as 
this part, owing to its laying very low, is 
subject to be enfiladed, and also because 
the saliant angles of the covert-way are 
sometimes abandoned from various causes 
there are at every forty or fifty yards para- 
pets, whose slopes point towards the exte- 
rior, or saliant angle of the covert- way, so 
that cannon shot may be stopped, and the 
defenders may make a stand from time to 
time, behind these parapets, (which are 
called traverses,) until at last forced into 
the out-works for safety from the pursuing 
enemy. Each traverse is made the whole 
breadth of the covert-way, namely, 30 feet ; 
their exterior ends would touch the pali- 
sades, were not little inlets made at right 
angles into the crest of the glacis, brekd 
enough for two or three men to pass abreast. 
The traverses may be about six feet high 
within, and about five without; there is* a 
banquette within which raises the defenders 
about a foot and a half, for them to stand 
upon, and to fire over the parapet, of which 
about ten feet is generally the thickness. 
Another method of passing the ends of the 
traverses is not uncommon, and is, perhaps, 
at least equally good as the foregoing ; this 
is by making a serrated line of palisades, 
as seen in the plate, in which the small 
black projections from the line of the 
ditch, represent the traverses, and the line 
bordering the glacis g, g, g, shews the line 
of the palisades ; not unlike the teeth of 
a key-hole saw. The vacant spaces -j-, 
-f-, -|-, -|-, in the re-entering angles, are 
for the assembling of troops for the de- 
fence of the covert- way, and are called 
places of arms. In these, sometimes, 
small redoubts are thrown up. Places 
of arms are always near to some sortie 
from an outwork, so that the parties posted 
in them may be readily withdrawn, or 
be reinforced ; in some instances, however, 
places of arms are made in the saliant 
angles of' the covert-way; but they should 
then be in some measure entrenched, or 
protected; else they would be severely, and 
perhaps unnecessarily exposed, although 
the covert-way is so far above their heads. 
The glacis is always made so as to give 
an inclined plane, corresponding with every 
change of direction in the line of the crest 
of the glacis ; not, however, adverting to 
the small inlets, or serrated appearance, 
required for passing the ends of the tra- 
verses. This will be seen on reference to 
the plate, where every such inclined plane 
is particularized. Such a disposition of the 
glacis is indispensable ; it gives the true di- 
rection of every part, as it respectively 
stands fronting to the line of palisades ; so 
that the soldiers can scarcely fail to aim 
properly if they fire straight before them, 
and rest their musquets on the upper rail. 
They thus graze the surface of the glacis, 
and consequently do great execution. 
An extensive defence, called a horn- 
work, is sometimes substituted for a crown- 
work. The latter, as may be seen, is com- 
posed of a full bastion between two cur- 
tains, whose exterior sides are terminated 
by demi (or half) bastions ; whereas the 
horn-work, in lieu of expanding as it re- 
cedes from the principal, contracts, and its 
front, (which should be parallel to that of 
the principal when it covers a curtain 
therein,) is formed only of a curtain, ter- 
minated by two demi-bastions. The out- 
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