J O I

79

JOl

0r ,.’ *15 : in this of 133, If is the thickness of wood extra-oi.u-y wanting on the back of the rail.”t a i . le m<; thod which Mr. Price employs at 132, for ascer-ttiyn"'® . l * le thickness of stuff by a falling-mould, or develop-in s ' de l * le rad > ' s i ncorrec,; > nor can it be found

0 p ‘ "“terminate manner without an orthographical elevation'vh l' 6 the wreath to be formed. This concludes the

tUid* *1 su ^ stai 'ce advanced by Price in the article Joinery,* 0ws improvement only in its infancy.m }' ** r 'ce has also shown the method of forming raking-dings for pediments, as follows :

W^i Alld ‘ n consideration that no pediment can be performedtwo kinds of cornice, (except it be lcnee’d at itst|, ^ or springing, which is reckoned a kind of defect,)a g f ? l ‘ e to give each of the cymas such a shape, or curve,c Urv 3 Stri<:tl y a gree in their mitre, do thus : Describe the8llch e °f.the level cornice f, Figure 134, as abc, by twottiav ? 01 t'ons of circles, as that the centres for forming each'niddi 6 a horiz ° nta * or level line, drawn through thetl, ' e °i the said cyma ; as * *, cd; being the projectureably t ° ‘ ** raw lines from the points of the said cyma, agree-t|, e | ? tl' e slope of the pediment, which gives or terminates<ll 'nvvi' S,ieSS 0 ' l * le t cornice or cyma G ; so that by

#re ( | "e a line through the middle of the said member, on itth e ? ei, tres * *, by which the curves efg are described ;^J'-ojccture, h g, being as before. In case a break or"t'lst | . Inai le in the pediment, then another kind of cyma

tke c 16 ^ottfed, which shall agree with the two former, asli;)ii le j ntl 'es for forming each curve being on an horizontalis the' aWn trough tl )e middle of the cyma, as before; iklkinds ( ''/ l . l ' Ve ’ w l'ose projecture, as before, is 1m. These threenthf.,. \ cor,1 ’ce being thus formed, will agree with eachbe 7‘I.out the trouble of tracing. But if the given curvein j.j. Uesci 'ibed as before, then observe the method proposediriay b ’ ky which the curve of any raking-mould whatevern °Ph • tlU ** r 'Inscribed. Admit the cornice given were k ;oi ( ^ e,n p its curve, and p q its projecture ; by making pointssaid curve, draw lines from them, agreeable to theare f ^ le P e< li m ent, on which place each respective pro-l0 m K to L, so is r s t its curve, the projecture being

b'a

as b ef(

Point^ *' le several projectures from k, observing that the

ol ’e. And if a break or return be made, as at, then

Pod

,'. Us be

"iient,

°n the lines drawn agreeable to the rake of the

as bef'. l ’ so w *l* be the curve, and y z the projecture,T|, e 6 .' wl'ich no doubt but inspection explains.”l>e (j Kt) 8c j lerile for raking-mouldings, shown at 134, is not toRaisin 7 j ^. u P on - If is evident that since the figure is a0Urv e ^ 1 since the given curve is composed of circles, theaide,., j e< P*ii'ed must be composed of elliptic segments,file easjg Motions are parallel to each other, which is notTin . ’

first t| ^second method, shown at 135, is perfect, and is thePubli Ci iJ||® kl n< * that is to be found in any English

%

Hio,,?^ now to the London Art of Building, by William«*,. !, s it is our province to repeat only the inven-

i' V l'ut Mr T’Paovements in joinery, we shall therefore omitj‘®ing > j ‘ Salmon has said on the formation of the scroll ;

deto 6 ^ 10 ^ and substance, the same as that which welut 'uiial Ued from Mr. Price, who certainly gave the first

rail tn 7 hod °f squaring the twist for the scroll part ofo °'vn ler fr° ra his own invention, or from a

11 -itnomr - ■ - - - — ■ ■

practice

fri'nii'p 11 ” ' V0ldcmen - And as Mr. Price has only shown7 il 'li'ai lt ! ( ] lon °f the twist of a scroll, and of a rail upon a?PplicatiQ n ^ an * n a level landing, we shall here detail thestair ! nade °f the same principle by Salmon to a wind*’ ‘‘ere the treads of the steps are all equally divided

around the circumference ; but first it would be necessary tonotice the candid acknowledgment which Mr. Salmon hasmade in respect to the principle.

“I must confess, for this method of forming twist rails.I have had my eye upon, and am obliged to, my ingeniousfriend, Mr. Francis Price, in his Treatise on Carpentry,lately published ; though, on comparing them, you will notfind them alike. This method of forming the raking-mouldwill serve for all twist rails whatsoever, with due application,as shall be shown in another example of a staircase, havinga circular well-hole.

“ Figure 136, is the plan of a circular rail having sixteensteps in the whole circumference; but here it is proposed tofind the raking-mould to a fourth part thereof, or four steps,it being to a small scale. The plan being laid down, asaede,Figure 136, divide the outer circle into a number of equalparts, so as to transfer them on some line, as a c, Figure 137 :and setting up the rise of four steps, as a b, gives the pitch-board, due to them all. Then taking be, in Figure 136,applied to the pitch-board, Figure 137, from c to d, it givesc e, which transfer to Figure 138, from b to c. Also, fromFigure 136, take a d, placed in Figure 137, from c to g,gives cf which transfer to Figure 138, from a to d; andthere tracing, as before taught, you will form the raking-mould required.”

In such a staircase as the above, the waste of stuff is great:but when does it ever come into practice, that the steps areequally divided? In every stair there must be a landing, andthis would require much thicker stuff: Again, if the stair ismixed with flyers and winders, the waste stuff would in manycases be enormous, and still more so, if the joint were broughtover the flyers, in order to secure the wreath and straightparts more firmly by a screw, as is the case in modern prac-tice. Tiie greater number of stairs now in use, are constructedupon this plan.

“ Some able workmen have another method of formingthis rail.

“ First, they make a cylinder, equal to the whole well-hole,/’, e, in Figure 136, or part thereof, either solid (if thewell-hole be small) or (if large) by fastening boards togetherupright, in the exact form of the plan.

“ Then they proceed to set on the said cylinder, asFigure 139, the height and breadth of each step, as a, b,c, d, e,f &c., and to the extreme points, b, d,f they bendround several thin pieces of the breadth of c f in Figure 137,and being glued, or otherwise fastened together, till theymake the thickness of the rail, I say these, when taken offfrom the cylinder, will be the rail, and exactly squared tothe right twist.

“ This is a very safe and sure method, though not veryfrequently made use of.

“ Either of these ways will serve, should the well-hole bean ellipsis, or any other figure for its plan.”

The first idea of gluing a rail in thicknesses is here shown,but the description, and the figures accompanying it, are veryimperfect; nor will the rail come off squared, as Mr. Salmonasserts, without the veneers are all different in proportion tothe radius of their plan, except, indeed, upon the plan whichlie has shown, where the rail is supposed to be continued,and therefore requires much amendment to be brought intogeneral use.

Langley’s improvements are as follow :

“ To describe a twisted rail. —Let the lines bde, Figure140, represent the edges of the two lower stairs of a staircase.

“ Divide b 9, the tread of the second stair, into nine equalparts, continue the line d towards the left at pleasure.Draw N f, parallel to 9 b, at the distance of seven parts, also

i

i