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 A R C H I T E C T U R E. 361 t»f the rail being firft ftruck by the mould, then apply on the rail; and’fo proceed with the other diftancee. the mould to the under fide, as much back as the level - Now, when the rail is put in its proper fituation, c perpendicular to b, and all the divifions, as 1, 2,will3, of the pitch-board fiiews, by being ftruck on the fide of be be. in the rail, will be perpendicular to 1, 2, 3, 4, &c the rail, and then fig. 3. being applied to the outfide of in4, the the rail, from its firft twilling part to 3, will Ihow how Fig.ground-plan. 6. Shews the plan of a rail of five fteps. much wood is to be taken off. rail. — Set five divifions, as from e to h, Fig. 5. Exhibits the fquare of the rail, with the ra- To isfindthetheheight of the five fteps ; draw the diagonal king-line of the pitch-board drawn through the middle hwhich on the upper fide; then draw the depth of the fide of x.q the plan of the rail; then take the diftance e f, and transfer it from g to h, and proceed in the fame manner the rail parallel to this, and the dotted lines from the with the other feven diftances. diagonal of the rail; thefe lines fliew what quantity of wood will be wanting on the upper and lower Tides of the To find the width of the rail-mould.—Draw the lines acrofs the plan of the rail, as at ^; fet that diftance from rail. Set your compafles at c, and draw the circular the ftroke from the raking part of the pitch-board to b; take diagonal to i; and fo proceed with tlie reft, as was the difiance a b, and transfer it from a to b, in fig. 7. (hewn in fig. 4. The feveral difiances thus found may be fet at any num- Having formed the fides of the rail perpendicular to ber of places, ranging with the ftraight part of the rail; its ground-plan, and having fquared the lower end of then take a thin lath, and bend it with the rail, and it then forms the width of the mould for the twill- astheisrail, reprefented by rn fig. 1. ing part of the rail. is the readieft method of fquaring a folid-rail; Fig.-7. Shews the fweep of the rail. The rail can- butThis not be fixed lefs than one fourth part from the nofittg or if the rail be bent in the thickneffes, the nofing of the fteps muft be drawn upon a cylinder, or fome other front of the fiep. The remaining part of the pitch-board may be divided folid body of a fufficient width to contain the width of into any number of parts, as here into four; from thefe the rail or ftring-board. divifions draw lines acrofs the pitch-board to the raking- r, Reprefents the depth of the rail, touching the nofe line ; then take the diftances from the ground-line of the of each ftep. Take a fufficient number of thickneffes pitch-board to the plan of the rail, and fet them perpen- of this width, to make the thicknefs of your rail; glue dicular from the raking-line of the pitch-board ; and them all together upon your cylinder or templet, confine thefe divifions, when the rail is in its proper pofition, lie them till they are dry, and the rail taken off is ready w fiquared. Proceed in the fame manner with the archidirectly over the divifions on the ground-plan. In this figure /, ni, and n, rife as much above 0 as trave, marked a. the dotted line in fig. 5. does above the width of the rail; and they fink as much below 0 as the other dotted OF ROOFS. line in fig. 5. falls below the width of the rail; the fame thicknefles mull be glued upon 0, though the greateft Plate XXXVII. Fig. 1. Shews the form of a part will come off in fquaring. The reafon of placing truffed roof, with three ring-pofts, that may carry feventhe letters /, m, and », where they are, is, that tl>ey ty feet, or upwards. might not obftnnfi the fmall divifions of the rail-mould. Fig. 2. Exhibits an AT roof, capable of carrying as Fig. 4. Shews how to find the rail when it takes great an extent^g^the former. Indeed both thefe demore than one ftep. The remaining' part of the pitch- figHS.,»i>e"Capabfe of carrying almoft any extent. board is divided into four parts, as before in fig. 7. and ' Fig. 3. Reprefents two different forts of trufles. it takes in two fuch parts of the next ftep. Draw lines Fig. 4. Shews the manner of piecing timber. Somefrom thefe divifions to the diagonal of the pitch-boam, times the joint may be extended as far as a, with another as in fig. 7.; then take the diftance a b, and fet it from bolt through it. To the right is fliewn a different fott of joint. c to d, and fo proceed with the other divifions. Another way to find the outfide of the rail-mould is, Fig. ?. Shews the manner of truffing a girder. If to draw all the divifions acrofs the plan of the rail; then the trulfes are full long, with the pieces b and c yoA take the diftance from the ground-line of the pitch-board may make them as light as you pleafe. to 4, transfer it from the diagonal of the pitch-board to 4 Fig. 6. Reprefents the manner of trufling partitions. ARC ARC Military Architecture, the fame with what is o- feene-work, in the painting of columns, &c. for the’ therwife called fortification. See Fortification. decoration of theatres. Naval Architecture, the art of building fhips. See Architecture, in perfpe<ftive, a fort of building, the Ship-building. members of which are of different modules, and diCounterfeit Architecture, that which confifts of minilh proportionably to their diftance, in order to proje&ures, painted in black or white, or in colours make the work appear longer to the view than it after the manner of marble, which is alfo called really is. See Perspective. Vol. I. No. 16.' 3 ARCHI4*