601 
FOR T I V 
more out of tlie way of doing damage to tlie town on an 
accident of blowing up, but are alfo nearer at hand to 
give inftant fupport to any of the works where they may 
■be wanted ; and here the troops fecurcly take their repofe 
when relieved from duty. Thefe magazines are ufually 
about twenty yards long by twelve broad iii the clear, 
and about eight feel high in the upright, befides the rife 
of the femicircular vault: the fide wallsdhould be about 
•nine feet thick at the foundations, and eight at the top ; 
the end walls about five at the bottom, and four at the 
top ; and that they may be bomb proof, the work mud 
be three feet thick in the reins, or juft above the fpringing 
■of the arch, and eight or nine feet thick in the crown or 
fop. The whole building fliould be ftrengthened on eacli 
fide by buttreffes fix feet by four; and in each fide there 
nuift be left in the folidity of the wall vent-holes to air 
the magazine ; which vents are to wind round a kind of 
■ihaft of about a foot fquare. 
Magazines may be conftruCted both in hollow and in 
folid baftions ; care being taken in the latter to leave an 
area about their walls, if the place is fubjeCt to damps. 
Some engineers place the magazines at the foot of the 
rampart along the curtains, in order, as they fay, that the 
baltion, by being left clear, may be difputed inch by inch 
with the enemy. But as there are very few examples, 
fince the modern practice of war, of Inch fanguinary 
refolution after an effectual breach is made, the reafons 
for having the baftions thus unincumbered with build¬ 
ings, are rather imaginary than real, and confequently 
have but little weight. However, when the ditch fur- 
nifties earth fufficient, it has been the practice of the 
mod celebrated engineers to make full baftions, efpecially 
if they were final 1, and with narrow necks. 
In the faliant angles of baftions, as at fig. 7, fuch as 
the flanked angle, and the angles of the fhoulders, it is 
nfual to conftruCt centry-boxes of done, to fecure the 
•centinels from the inclemency of the weather, and againft 
random fiiots. They are alfo furniflied in the fides with 
loop-holes, to obferve what is doing in the ditch and co¬ 
vered way, and alfo to fire through upon an enemy when 
occafion offers. The plans of fuch centry-boxes may be 
either fquare, circular, or pentagonal, and their floors are 
to be 011 a level with the walk of the rampart: their 
communication is by a paflage of about three feet wide, 
bricked on each fide, and cut through the parapet. 
Prob. V. —The majlcr.hne of a fortrefs being given, todraw 
the plan of the fofs and efplanade .— On the flanked angle B, 
-fig. 4, of each baftion, with the radius BC equal to the 
breadth of the fofs found in the preceding table, defcribe 
the arc C C. Lay a ruler to touch each arc at C, and the 
angle E of the neareft flioulder of the next baftion, and 
in that direction draw the lines C p, meeting one another 
in p. From the flanked angle of each baftion draw lines 
B q at right angles to C p. In each of the lines By, take 
Ca= 10 yards as in fig. 4; Co=i2 yards, and Cy=6o 
yards. Through the points, a, 0, q, draw lines parallel 
to C p, meeting before the middles of the curtains at C 
and t, fig. 3," and before the flanked angle of the baftions 
in x, y. Then w ill BC reprefent the breadth of the 
fofs; C q, the efplanade ; Co, the covered-way ; ao, the 
foot-bank; cq, the glacis; The arcs C C, reprefent the 
roundings of the fofs; The lines C p, the counterfcarp ; 
x C, the head, xy, the ridges, s t, the valleys, andj y t, 
tl'.e foot, of the glacis. By this improved mode of con- 
ftrufting the counterfcarp, all the fofs is feen from the 
flanks, and confequently is defended by them ; which 
nuift be infinitely more advantageous than if the coun¬ 
terfcarp was directed to any other part of the flank, the 
intercepted part next the fhoulder being by that means 
rendered ufelefs for the defence of the ditch ; neverthe- 
lefs, if on any occafion it fhould be neceffary, the direc¬ 
tion of the wall of the ditch may point within the fhoul¬ 
der by the thicknefs of the parapet of the face, and ftill 
the fofs will maintain the whole defence of the flank. 
Vol. VII. No. 453. 
[CATION. 
Fortifications in general would be very defective with¬ 
out foffes; which fhould, in all cafes, if pofiible, be fo 
conftrudted as eafily to be filled with water, and drained 
at pleafure, by the help of Unices or floodgates; but as 
this advantage cannot be had every where, the ditch nuift 
be adapted to circumftances, and fituation of the place. 
In dry foffes a row of palifades is ufually planted along 
the middle, either upright, or doping towards Che coun¬ 
terfcarp 20 0 or 30° from the upright. In fomeft dies, 
where water can be had, a trench called Cuvette, as (hewn 
at mi, fig. 12, is dug along the middle, of about twelve or 
fifteen feet wide and fix feet deep, for the water to flow 
into. The breadth of the fofs, although unequal in it- 
felf, is ufually meafured from the flanked angles, before 
which it is always rounded ; the depth here may be Irom 
fifteen to twenty feet, and thence rife gradually to the 
middle of the curtain where the depth might be four or 
five feet lefs. 
Of fortified GATES.—A Gate, in a fortified place, 
is a paffage through the rampart, which can be Unit up 
or opened by the means of doors and a portcullis. A 
Portcullis is either a Ileije, confiding of ftrong pieces of tim¬ 
ber framed like a lattice, the lower ends of the upright 
pieces being fliod with pointed iron, and the whole fiame 
let down by chains, or Orgues, confiding of feveral long 
pieces of timber not framed together ; each hanging by its 
particular chain,.the ends of which are wound round a wind- 
lafs, which lets them all down equally together. The ule 
of a portcullis is to flop the gateway in cafe of a furprife ; 
and in this, tlie orgues are by much the bed contrivance ; 
for a herfe may be broken to pieces by a petard, or by 
cannon (hot: but fhould a beam in tlie orgues be ftruck 
off in the middle, the upper part will defeend to fupply 
the place of the part taken away.—Fortification gates are 
either public or private. Private cr pojhrn Gates, are thole 
paffages through the rampart by which the troops can go 
out of the town unfeen by the enemy, when they pafs to 
and from the relief of the duty in the outworks; or oil 
any other occafion which is requilite to be concealed irom 
the befiegers. Public gales are the principal paffages 
through the middles of the curtains, to which the high 
roads or public ways lead.—They are projected in the 
centers of the curtains, as being the bed defended part in 
the outline of the rampart. 
The common dimenfions of a principal gateway are 
about fourteen feet high, and ten feet wide, with proper 
avenues for the foot-palfengers where fufficient fpace can 
be allowed for fuch a convenience; othervvife recelfes 
mud be projected for foot people to ftand in while the 
carriages pafs. The ftyle of architecture nuift be either 
the Tufcan or Doric, and the palfage covered with a 
ftrong vault. Over the vault, and clofe to the wall, is 
ufually eredted a building of about twenty feet fquare, 
in which is fufpended the portcullis ; and on the infide 
of the rampart there is generally railed another building, 
of about one hundred feet in front and thirty deep, and 
high enough to contain one or two floors of rooms lor the 
officers, the ground floor ferving lor guard-rooms for the 
troops who do the duty at the gates. 
To conjlrucl the Plan of a Gate nuith the adjoining Buildings. 
—Let the line ac , fig. 9, reprefent the thicknefs of tli’e 
bafe of the rampart, and the middle line of the gateway; 
in which take the following meafttres in feet: aj : 
fr— 6 \ rh— 18; ci— 30; and 012=15; through thefe 
points, lines being drawn parallel to the curtain, take 
fdr=.4\\— rg— 9; <1/2=50; and hi— 6 feet, and 
complete the figure. Then bg reprefents the plan ot the 
frontifpiece ; gh of the portcullis room ; ik, of the arcade 
or guard-houfe ; and Ik is the breadth of the afeent to the 
rampart. 
Of the difpofition of the Streets in a Fortification. —When a 
new town is intended to be fortified, and all that relates 
to the rampart is projected with regard to lituation and 
fize ; then the plan of the ftreets remains to be confidered ; 
■ q o and 
