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If the cistern be to be raised on high, where walls cannotbe constructed around, it may be made of timber, in theforegoing manner, and lined with lead: but as this liningtends to contaminate the water, the casing of the exterior withstone or brick, with puddle between it and the woodencistern, should be adopted when practicable.
A cistern may be constructed for watering cattle, by exca-vating the ground where there is a descent, and covering thebottom and sides with two coats of tough clay, each coat aboutsix inches thick, well rammed; the bottom being coveredwith flag-stones, the clay will remain moist, and free fromcracks, though not covered with water. But this is trouble-some ; for, should the clay happen to crack in any part, itwould be necessary to go over the work again.
In a chalky soil, a cistern may be formed by digginga hole, and covering the bottom smoothly with chalk rubbish,which, when wetted by the rain, should be rammed well.Afterwards cattle may be turned in to tread it till quite firm,j and then it will be impervious to the water.
! CITADEL (from the French , citadelle, a diminutive of! the Italian, citta ) a small city.
j Citadel , is also a small fortification, consisting of four,j five, or six sides, with bastions, by which it is distinguishedI from a castle, and usually joined to towns, and sometimes| erected on commanding eminences within them.
1 Citadels may be either square, rectangular, pentagonal,j hexagonal, or, indeed, of any figure ; but the pentagonal ismost commonly adopted. The hexagonal is generally con-i sidered as too large, and requiring too great an expenditurefor the advantages to be derived from it; and the quadrangular! is incapable of making a sufficient defence. Citadels are alsoI sometimes made in the form of a star fort.
The exterior sides of the citadel, when its plan is regular,i are generally, each about 150 toises, or fathoms ; but this' extension may be varied according to circumstances.
When the citadel is erected on a hill, or eminence, withinthe fortifications of the place, it is well calculated to keep| the inhabitants in awe, if the garrison be sufficiently provided;
I but it is of little use against an enemy, when once in posses-\ sion of the town itself.
' ! The citadel will require a stronger fortification than thej town, to prevent its being attacked first by the enemy, who,
1 getting possession of it, will soon become masters of the town.
A citadel has, for the most part, two gates, the one for com-; municating with the town, and the other with the country ;
1 the gate communicating with the town, is used in case of ani j insurrection or sedition, or after the town has capitulated,
J for the garrison to retire into the citadel; the other gate,i which communicates with the country, is for receivingassistance and succours when placed under extremities.The citadel generally takes up two sides of the fortificationof the parts which adjoin to it, and should be so constructed,that the ditch of the place may be defended as directly aspossible’, either by the faces of its bastions, or by ravelins,that the enemy may have no greater advantage in attackingin one place than they would have in another. It may befarther observed, that in an extensive fortified city, a citadelmay be formed by uniting two adjoining bastions, by a goodretrenchment, with flanking defences: the expense of makingsuch is very trifling, compared with that of adding anotherfortification to the place.
CIVIC CROWN, in Roman antiquity, a garland of oak-leaves and acorns, or ground oak, given as a reward to suchas had saved a citizen’s life in battle.
, CIVIL ARCHITECTURE, that which embraces thej erection of edifices destined for civil purposes; the term is| used in contradistinction to military and naval architecture.
CLAIR-OBSCURE , or Chiaro-Oscuro (from thechiaro, light, and oscuro, dark) the proper distributl ^light and shade in a picture, both with respect to tn. ^and the effect of the whole composition. The term ) 3used for a
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, design wherein only two colours are used,usually black and white. , 0 f »
CLAMP, a small piece of wood, fixed to the on
board, to prevent it from warping, the fibres of thebeing transverse to those of the board. The inan ^ theclamping a board, is either by grooving the edges j 3clamp, and tonguing the ends of the board into it wit" ^gand glue, or by grooving the end of the board, and to t> j 3the edge of the clamp. « Sometimes the end of the c ‘ r jj.mitred to the side of the board, for the sake of neatermanship. In the best clamping, the clamp is fixedboard with a mortise and tenon.
The flaps of shutters, small doors, lids, and kitchen* ^which consist only of boards glued together, arefrequently clamped. _ 0 D 9
Clamp, in brick-making, a pile of bricks built rrectangular base, for the purpose of burning them. ^ ofClamps are built of unbaked bricks, after the ,naI J )I .jcli s 'a kiln, with a vqcuity between the breadths of th e ^ infor the fire to play through; but, instead of arching, j eC tkilns, the flues are gathered in, by making the lay® 1 " 3 upone over another. The place for the fuel is ca .^ r - 9 th eI lstraight on both sides, till about three feet high; tul0 o>nearly filled with wood, which is covered with a stra aI) n e ^'small sea-coal, or breeze, after which the flue is over ?^rick s ’The sea-coal is also strewed between every row 0 0 f i®and the top of the clamp covered with a thick ^ a ^ e n jc» te ^The wood is then kindled, and the fire is thence com® 1 ^];^ 9to the coals. When the fuel is exhausted, the brick'conclude that the bricks are sufficiently burned. . ^ c0®'The operation of burning bricks, is attended w ^siderable difficulty, and requires workmen of exp eI ^ jf tk 3maintain an equal degree of heat throughout the m® ", a®°heat be too low, the bricks will be weak and crU ,® T& 3if too strong, they will vitrify and run toget" ^^ps ’operation is much better performed in kilns, than ® j a te^ 3 ,as in the former, the fire can be kept up, and re ^ [ie \ jfl® 3discretion; while in clamps, as the whole of the uS e t0 Tbe put in at once, the manufacturer is tempted j er „bt)®? jlittle, and the outside bricks are consequently 1111 j D fer'°These are called samel-bricks, which are sold at 8
price.
Clamp Nails. See Nails. . ho0
CLAMPING, in joinery, the act of securing 8
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clamps. See Clamp.CLASP NAILS.
See Nails.
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CLASSICAL ARCHITECTURE, such as w® 3 Pby the Greeks and Romans. . 0 r W®
CLATHRI, in Roman antiquity, bars of i r ° n ’
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used for securing doors and windows. . ^ p,
CLAY, in common language, any earth wh® ^sufficient ductility to admit of being kneaded wit
Common clays may be divided, with regard to * re0 o9.into three classes, viz. unctuous, meagre, and calc j]ia® e $The unctuous contains, in general, more alumi \Y® - 3meagre, and the silicious ingredient is in finer g ra te jto r %burnt, it adheres strongly to the tongue, but its d0 o^ynot visibly porous. When charged with little 0 . r Jof iron, it burns to a very good white colour, 8 ..fact® 1 ?,^infusible; it is therefore employed in the ( natl 0 rpStaffordshire ware. When it contains oxide of * r0D p |Jg jbl®> “sufficient to colour it when baked, it becomes mor ® ter y.can only be employed in the coarser kinds of p° l
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