R A V
360
REC
a parapet is raised upon it with a platform. Hence, also,earth not being capable to be raised perpendicularly, likestone, the rampart is built with a talus, or slope, both on theinner and outer side.
The rampart is sometimes lined, i. e. fortified with a stonewall withinside, otherwise it has a berme.
It is encompassed also with a moat, or ditch, out of whichthe earth that forms the rampart is dug.
The height of the rampart should not exceed threefathoms, this being sufficient to cover the houses from thebattery of the cannon: neither ought its thickness to be aboveten or twelve, unless more earth be taken out of the ditchthan can be otherwise bestowed.
The ramparts of half-moons are the better for being low,that the small fire of the defendants may the better reachthe bottom of the ditch; but yet they must be so high as notto be commanded by the covert-way.
Rampart, in civil architecture, is also used for the spaceleft void between the wall of a city and the nearest houses.This is what the Romans call pomarium, in which it was for-bid to build, and where they planted rows of trees, for thepeople to walk and amuse themselves under.
RAMPS, in fortification, gentle slopes made for the can-non to be drawn up and down by, and also for the easy com-munication of the troops posted in a battery raised above thelevel of the ground. The rise of these slopes is about twoinches, on twelve of base; or the length of the base is sixtimes the height, and this is general for the draught of car-riages; but footways need not be of so gentle a slope, as arise of one foot in three may answer the purpose; or, insteadof ramps, stairs may be, and commonly are, used for thepassage of the foot. The breadth of a carriage ramp isusually about nine or ten feet; but those for foot-passageonly need not be above three or four feet wide. Ramps mayeither rise on the side of an elevated work, or against asalient angle of that work, or on each side of an enteringangle.
RANGE, or Ranging, (from the French , ranger, to placein ranks,) a term applied to the edges of a number of bodies,placed in a given surface: thus, if the edges of the ribs of agroin were placed in a cylindric surface, they would be saidto range. It is also used in speaking of the side of a workthat runs straight, without breaking into angles.
RASP, a rough file.
RATE, in architecture, the particular class of a building,under which it is arranged, as to the quantity of ground onwhich it stands, its height, or destination.
This classification is only used in the neighbourhood ofLondon , in order to modify the construction according to theregulations of the Building act. See House.
RAVELIN, in fortification, was anciently a flat bastion,placed in the middle of a curtain; but now it is a detachedwork, composed only of two faces, which make a salientangle, sometimes without, and sometimes with flanks; andraised before the curtain on the counterscarp of the place;serving to cover it and the adjoining flanks from the directfire of an enemy. ]
A ravelin is a triangular work, resembling the point of abastion with the flanks cut off. Its use before a curtain is,to cover the opposite flanks of the two next bastions. It isused also to cover a bridge, or a gate, and is always placedwithout the moat.
What the engineers call a ravelin, the soldiers generallycall a demi-lune, or half-moon.
There are also double ravelins, which serve to defend eachother. They are said to be double when they are joined bya curtain.
rea<>- . stsand con
UiVtC WllCt/iy l/UUJUU X J, AllAViN , Vi 9*
usually of one or two sloping-desks of sufficient w ^ e y at®tain the books raised upon a pedestal or standard; yjetfmostly made of wood, but frequently of brass or o ^ 1"and is enriched with various degrees of ornament® e8 gl®many cases, the stem or pedestal was surmounted bywith outspread wings, on which the books rested. , g r e,REBATE, or Rabbet, (from the French , (’f in 8abate,) a deep groove, or channel, cut longitud 1 end?piece of timber, to receive the edge of a plank, or £ ag ten e “of a number of planks, which, are to be sec ” r k e V<into it. The depth of this channel is equal to tn l3 le
of the plank, so that, when the end of the D 0 f tn®
into the rebate, it will be level with the outsi
P iece ‘ in a f 1 ’.
RECESS, (from the Latin , recessus,) a cavity
' - - - t —
left either for ornament or use, or for both p ur P 0S . ture ,for use, when it is to receive some piece of forsideboard, or to add to the size of room ; an j )eaU ty a ?._ment when made in the form of a niche, to give , t j,e e® 1
variety to the building. When the construction
fice requires some of its walls to be of very g rea j esg eb 1 {niches are frequently taken out of the wall, to g0 tb^thickness and give a greater quantity of floor-roe
ihema‘ iCa ® atbe JesP®-
use
utility and ornament are united, and the e:rials is saved.
RECIPIANGLE, or Recipient-Angt.e.instrument, serving to take the quantity of angle ,daily in the drawing of plans of fortifications, a
The recipiangle was formerly a popular ’. nS ? rU ugU ally ?the French , but little known among us; it 18simple, in form of a square, or rather a bevel,two arms, or branches, riveted together, buta sector, on the centre or rivet.
cons 19 ? 111 ?));®m ovea ble ’
id
tor i® 1,111
To take an angle with it, the centre of a t [je
j-v tcitvc uxi angle wim it, ute eeuww j
to the joint, and the degrees cut by the edge 8 10 uy tb e_£■ otherwise the angle ma ® a -
paper, and then measure ,
degf S de >the js
it, wiui an muw* i ty&Q*
At other times the una
iabS le
»
over the centre^or^’ 13 & CI ' rcIe (livi,led int0without a protractor ^ WUfl an index t0 sil0 fdivided.
To
a PPly tlie^Tsb? a sal ’ ent angle with any of the TeCl %f. fre'DeS that *nn tie angle; a
RECTANCTP P /r the 0Uts,des > &c - . „iled » l ‘ J
long an d ’ ( rom the Latin, rectangulus, ) c oS e,
9 d lmg Sf iuare, a quadrilateral rectangular- - - -^tangle * a P
oblong, a..u -y—, - u—— ecta ngr
whose opposite sides are equal. Ur, a ^lelogram, whose angles are right. _ ^ ^ figures
RECTANGULAR ? a term applied t0 . squwhich have one or more angles right- S uc n„uttgles, and rectangled triangles, among p ia
, s ol iiS
aDd v*
.areSi
figures
cu 1
be®'
to
parallelopipeds, &c. among solids. . . r esp e ®? u ]»r f°
_ be rectangular witn nd i C u i, t
■ or
situation: thuTi/l^ *° be rec tanguuu .
the plane of the it C ° ne ' cylinder, &c. be perpenCo ”®> Cylinder, See r,zoa > it is called a rectangular
denote a parnh^i tbe P^ rase rectangular section of® - u s,bmn S only colder V . tLat co ™ section, before Apo °° i3
w rfd be a tSS . a a con ^ whose section by***
Hence it wasth ysnt-aogled at the vertex. ■ c tbeS that Archimedes entitled his book— of liectany
Co
quadrature of the parabola,Sectio.
by the name