FORTIFICATION. 
yard', between 200 and 350, as many as its length will 
admit of, which may then be confidered as compofed of 
fo many polygonal (ides. At every divifion, projeft fuch 
a baftion as the limits will admit, taking care that the 
faces of each can be commanded by the adjacent flanks 
of the next baftions. 
When any of the angles become too acute to make in 
that place a whole baftion, the angle may be diminilhed 
only on one fide, making there a half baftion, and let the 
other fide be either left as one line, or make two or three 
fmall flanks in it, in the nature of a redan ; obferving that 
the whole front mud be commanded by the flank of the 
next baftion. Or fhould the angle be too fmall even for 
a half-baftion, then both fides may be fortified in the 
manner of redans, and commanded from the flanks of the 
next baftions; but, in the cafe, of thefe acute angles, the 
angular point fttould be made very folid, and the fides 
about fuch angle fliorter than the others. 
Should the polygon have one or more entering angles, 
which cannot be avoided when that angle is near ninety 
degrees, and the adjacent fides do not exceed 250 yards, 
thofe fides, with the afiiftance of the flanks of the next 
baftions, will very well defend one another, and alfo the 
entering angle: but fhould the angle exceed 120 degrees, 
then put againft that angle a work like a baftion, if it can 
be done ; or if there is not room for the projeftion of the 
flanked angle, make but one face, fo as that it may be 
raked from one of the adjacent flanks, in cafe it fhould be 
attacked or taken by an enemy. 
To render what has been dated above more obvious, 
let fig. 6, in the Fortification Plate III. reprefent a place 
irregularly fortified in an oval figure. Here the fides 
CD, GH, on the flat parts, are ftronger than the fides 
AB, E F, on the narrow parts, fuppofing all the exterior 
fides equal, and the place equally fortified. When the 
angles BCD, C D E, of the polygon are very great, and 
the befieger comes within a fmall diftance of the works, 
he cannot approach nearer, without being feen in front, 
except by a diredt flip, with traverfes; and as this way of 
approaching prefents but a fmall front, the befieged, who, 
have a much larger, may oppofe with peculiar advantage 1 
whereas, if the angles H A B, ABC, of the polygon, are 
very fmall, the befiegers carry their approaches to the 
counterfcarp itfelf, and have always a larger front than 
the befieged ; and, as the befiegers.muft extend their ap¬ 
proaches to three fronts, whether they are fmall or large, 
the work of the approaches before the front B C DE will 
be to the work before the front HABC, as the line B E 
is to the line HC, nearly, i. e. as the greater axis of the 
oval is to the lefs; and therefore the front CD, on the 
flat fide, is ftronger than the front AB, on the narrow fide ; 
confequently, the longer CD is, fo that the lines of de¬ 
fence are within the reach of mulket-fhot, and the angles 
BCD, C DE, are the fame, the ftronger will the front 
be ; fince the works become more l'pacious, hold more 
troops to defend them, and the befiegers are obliged to 
extend their trenches farther. Moreover, the greater the 
angles of the polygon BCD, C D E, are, the exterior 
iides being the fame, the ftronger will be the front CD ; 
becaufe the length of the line BE increafes, and the ex¬ 
tent of the befiegers approaches in proportion ; and, 
therefore, the ftrength of a fortification increafes in pro¬ 
portion to the number and length of its fides ; fo that a 
dodecagon is ftronger than an odtagon, when the length 
of their fides is the fame. However, as it is found diffi¬ 
cult to infcribe a polygon in an ellipfe or oval, the fol¬ 
lowing more eafy method will anfwer the purpofe. Re¬ 
duce the fpot of ground to be fortified to the figure ACEG, 
and draw BE, AF, parallel to each other; draw CH, 
DG, perpendicular to thefe lines, and at equal diftance 
from the, points B and E, and let their interval be equal 
to that of the lines B E and A F : then, draw D C, G H, 
parallel to A F and B E, and equally diftant from them ; 
and from their interfeftions C, D, G, H, with D G, C H, 
as centers, defcribe arcs, with a radius equal to C D, or 
f507 
G H, fo as to interfeft the lines A F, BE, in A. B, E, F; 
join the points A, B, E, F, and ABCDEFGH, will be 
an oblong odtagon, having one half fimilar and equal to 
the other half. If a hexagon be to be defcrihed, inftead 
of drawing the two lines C H, D G, one will be fuffi- 
cient; in a decagon there muft be three, and four in a 
dodecagon. If the fides cannot eafily be made equal, then 
the fides A B, E F, on the narrowed part of the polygon, 
fhould be the longeft, becaufe it is the weakeft. But 
when the figure cannot in any refpect be made regular, 
the ftrength of each fide muft be eftimated according to 
the works a befieger is obliged to make in the attack, and 
according to the obftacles he meets wdth in his approaches, 
OF MARINE FORTIFICATION. 
This department of military architedhire is chiefly con¬ 
fined to the protection and defence of harbours and roads, 
and for the fecurity of (hipping. Harbours may be dif- 
tinguifhed into two kinds, artificial, and natural. Artifi¬ 
cial harbours are fuch inlets of the coaft as are rendered 
tenable for (hipping, by building moles or piers about its 
entrance, which defend the (hips within from attacks 
without. When the moles or piers can be brought fo 
clofe as to be (hut up by fluices or gates, the harbour is 
then called a baj'on ; though the inner part of a harbour, 
where the (hips ride in (fill water, is alfo commonly called 
a bafon. All artificial ports are eafily fortified by bat¬ 
teries, redoubts, or forts, which command the entrance 
into the harbour ; and which are always very carefully 
projedted in the regular fortification of a feaport town. 
Natural harbours are thofe where the natural figure of 
the land forming them, is fuch as contributes to the fafety 
of the (hipping, by (heltering the veffiels frpm the fury of 
the fea ; and this happens in various ways ; as by a ftioal 
lying off the harbour’s entrance, which breaks the waves, 
and keeps the water calm within ; or by the points of 
land which form the harbour’s mouth, ftretching tliern- 
felves fo far into the fea, and coming fo near each other, 
that the (urges are broken at their entrance ; or by a nar¬ 
row inlet that runs into the land for a confiderable way, 
where the fhores near the entrance receive the (hock of 
the waves, and render the upper parts fmooth and (till ; 
or by a large deep bay, where iflands, or rocks, contri¬ 
bute to render a part fecure for the riding of (hips at an¬ 
chor. There are many fituations in which fhips ufually 
anchor, that lie open to the fea, and yet are fafe to ride in 
when the weather is calm, or when particular winds 
blow ; fuch anchoring places are called roads. All thefe 
depots for (hipping are to be fortified in a manner con¬ 
formable to their fituation and extent, and as circum- 
ftances, with refpedt to their fnores and bearings, (hall 
feem to warrant, as the moft effectual for their permanent 
defence. When a town lies open to the fea upon a curved 
or (Iraight bold (liore, and has before it a fufficient depth 
of water, and good anchorage, within gun-(hot of the 
(liore, it may be well defended by forts erected near 
the water’s edge, on each fide of the anchoring place ; 
fuch forts, however, fo contrived as to have two or three 
batteries, one higher than the other, furniftied with heavy 
cannon, carrying (hot from twenty-four to forty-eight 
pounds; thefe will awe the (hips of an enemy, and in 
general prevent them from undertaking any thing againft 
the veflels that are lying in the road. But, to defend the 
town itfelf, there (hould be a rampart or wall, well flank¬ 
ed, built along the fhore, and carried fo near to the water’s 
edge, that were troops to land under the cannon of a fleet, 
they might not find ground fufficient to entrench upon. 
Forts built on a bold (liore, to which (hips of war can 
approach within mu(ket-ftiot, are the moft eafily taken, 
unlefs proper precautions are tiled. For as the batteries 
on (liore dre feldom raifed much above the water’s level, 
in order to be more certain of their mark, the troops polled 
at the guns are liable to be commanded by the marines 
quartered in the elevated parts of the (hips. This may 
be prevented,, either by driving fuccellive rows of piles 
flaod. 
