JOINERY. 



211 



The tame principle i* also applied to the bars of a 



bow wimlow, of which the sides form a polygonal prism. 



ie triiiflrnl i* considered as formed by the 



face of one of the vertical planes ; a vertical plane bi- 



secting the two adjoining face* and a horizontal plane. 



Let as mppotf the inclination of the two plane* 

 through which the plane of the mitre [ asse-*, and the 

 other two angle* of the trihedral to be given. The pro- 

 jection of each mitre, and the figure of the mitre, or 

 the section of one of the moulding and the mitre line, 

 must also be given, and we shall have sufficient data 

 in order to ascertain the section of t ,e other moulding. 



Thin uinetiauiim become* very e.ny, where the in- 

 clination of the two plane* is a right-angle, and when 

 the angle contained by the edge* of the one plane i* a 

 right-angle, and that contained by Uie edges of the 

 other an obtuse angle, a* is the ca*e with a pediment. 

 The plane of the two adjoining walls is generally a 

 right-angle, and the angle contained by two of the 

 edges of one of the plane* i* an obtuse angle, and that 

 contained by the two edge* of the other a right-angle. 



This case aiFards a very easy construction ; it being 

 only necessary to lay down the side of the building on 

 which the pediment or inclined cornice is to be made, 

 with a projection of die moulding* at the lower end, 

 without any plan whatever, provided that the mould- 

 ing* have the same prefecture on both tide*. 



The same i* also the case with regard, to the two sides 

 of a bow window, where the aide* are vertical plane* 

 at any angle* with each other. 



Fig. 1. Plate ' .ews the elevation of a 



triangular pediment with a modillion cornice. 



Fig. 2. Shew* the elevation of an open pediment with 

 the same cornice u Fig. I. It i* in Mich example* a* 

 the** that raking moulding* occur. 



Fig. S. Shew* the method of tracing a raking cima- 

 rccta. The curve tamed toward* Fig. *. i* the return 

 malisiag in -the open part of the pediment. Fig. 2. 

 The carve next to the margin of the plate is the return 

 aiding at the lower rxtrrmitie* of the pediment*, 

 Fig. t. and 2. The middle carve i* * section of the 

 raking or inclsMd moulding itself. 



Fig. +. Shew* the front of a modillion, with the raking 

 moulding which forms the rip. The upper extreme 

 i* a section of the level return at the top ; the lower ex- 

 treme carve is a section of the level return moulding 

 at the bottom ; and the carve shewn in the middle is a 

 of the raking moolding itself. This is the same 



7. 



Fig. 7. Section of a raking architrave and soffit for Joinery. 

 the return of a splayed window, which is sometimes 

 both necessary and ornamental in thick walls. No. 1. 

 is the architrave for the soffit, which we shall suppose 

 to be given in order to obtain No. 2. Let DF repre- 

 sent a section of the plane of the face of the sollit, then 

 to find any point in the curve, draw E e perpendicu- 

 lar to DF cutting C./", the face of the raking architrave, 

 at /'; make fe equal to FE, and e will be a point in the 

 raking moulding of the splayed architrave. Other 

 points will be found in the same manner, and when a 

 sufficient number are obtained, the curve may be drawn 

 through these points by the hand. 



Fig. 8. I* another design finished with reeded mould- Fig. 8. 

 ing* ; the method of tracing is the same, but this is 

 more particularly explained in the next figure. 



Fig. 9-1* the method of tracing the moulding of a rak- Fig. 9. 

 ing architrave more particularly explained. The mould- 

 ing chosen for this, purpose is an ogee reverse. No. 1. 

 is the given moulding. No. 2. the raking one, which 

 it required to be found. AE, e B, are the edges of the 

 mouldings, which are supposed to bo in the plane of the 

 ng of the walls. EF and c/'are the fillets which 

 front each other. FCi, /', the Miles ot'the quirk: of the 

 moulding*. I bi, ' k, the faces of the fillets. LK, lie, the 

 returns of the same, and IQl'HONG.and i q jtk oug, 

 ogee mouldings. Then to find any point A in the curve, 

 draw H h parallel to AB, and supposing these mould- 

 ing* to be of equal thickness, draw a e perpendicular to 

 BC ; make a e equal to AI ; draw MM perpendicular 

 to AE, cutting it at M ; make a m equal to AM, and 

 draw M k parallel to BC, A will be a point in the rak- 

 ing moulding a* required. In the same manner, all 

 the other point* will be found and completed as before. 



Fig. 10. I* a torn* moulding for skirting stair*. The Fig. 10. 

 curve at the lower end shows the section that the mould- 

 ing at the return make* in the passage below. The upper 

 is a section of the moulding on the return at the 

 landing. The middle curve i* a section of the mould- 

 ing placed in the staircase itself. This form of oblique 

 curvature* would only take place in a straight flight of 

 stair*, where the step* both begin and end in the pas- 



Fig. 1 1. Shews the method of mitreing skirting, where Fig. 11. 

 the wall of a staircase is continued before the first step, 

 ami after the landing. 



Fig. 12. Shews another method, by taking away the Fig. 1?. 

 angle*. Thus take two equal distances AB and AC. 



odtllioa M shewn "in the design* of Figs. 1. and 8. Draw BD perpendicular to AB, and CD perpendicular 

 Fig. 5. Shews the section of a raking cavetto, and to AC. Then with D a* a centre, describe the arc BC, 

 that of the return mouldbag at the bottom. which i* the curve required. 



Fig. IS. Shew* the method of finding the form* of Fig. 13. 

 the bars of a, bow window. The principle is the same 

 M described in Fig. ' i* a section of the given 



bar. No. '2. is a section of the raking bar in the mitre 

 of an oblique angle. No. 3. section of the bar in aright 

 .. ,. . 



moulding 



Fig. & Shews the sect**! of a raking i oln, and the sec- 

 tions of the return mouldings at the top and bottom. A* 

 the principle of all these i* the same, though the forms 

 are different, we shall here des erica the method of tra- 

 cing these curve*. Admitting the curve ABCDEK at 

 the bottom to be given : draw lines B b 6, ( ' c c, D d 4, 

 E e f, V tf, parallel to A a a. or to the fillet* of the 

 mouUlmg: Draw Al. BK. LI., DV rpen- 



dicular t<> 1 '.. and draw any straight line IKI.MNn 



IK. K.I 



and draw the straight 

 , and a b c d e f i* the sec- 



tion of the raking moulding. In the same manner, by 

 drawing any straight line tklmno parallel to J-G, and 

 drawing ia,k h, Ic, m d, me, of, perpendicular t" 

 we shall obtain the curve Ac de f, and the lower side of 

 M 8ll*t far the section of the return moulding at 

 Usetop^ifany- should be wanted. 



parallel to FfJ, place the distal* 

 pon any part of the fillet, 

 line* i a, k b, Ic, md,nt 



Formation of Bodiet i* Parti by joining them nith Clue. 



Plate CCCXX XVI Fig. 1. No. 1. Is a section of two 

 board* glued op edge to edge. No. 2. face of the came. 



Fig. 2. A section of two boards glued edge to edge, 

 with a tongue inserted in a groove in each piece. 



By these means, a board may be made to any breadth, 

 ihnaflh the pieces which compose it be ever so narrow. 



Fig. S. Two boards fixed at right angles, the edge of 

 the one being glued upon the side of the other. They 

 are strengthened by a block, which is fitted and glued 

 to the interior side*. 



Formation 

 of bodieiin 

 parti by 

 joining 

 them with 

 glue. 



PLATE 

 cccxxzvi. 

 Fig. 13. 



