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In ours, the modern proportions are, to make the diameter 15times the thickness of the brim, ami the height 12 times. Theparts of a bell are, 1. The sounding bow, terminated by an inferiorcircle, which grows thinner and thinner. 2. The brim or that partof a bell whereon the clapper strikes, and which is thicker than therest. 3. The outward sinking of the middle of the bell, or the pointunder which it grows wider to the brim. 4. The waist or furniture,and the part that grows wider and thicker quite to the brim. 5. Theupper vase, or that part which is above the waist. (1 The pallet"'Inch supports the staple of the clapper within. 7. The bent andhollow branches of metal uniting with the cannons, to receive theiron keys, whereby the bell is hung up to the beam, w hich is itssupport and counterpoise, when rung out. The business of bell-fotmdery is reducible to three particulars. I. The proportion of ahell. 2. The forming of the mould. And, 3, The melting of themetal. There are two kinds of proportions, viz. the simple andthe relative; the former are those proportions only that are betweenthe several parts of a bell to render it sonorous; the relative pro-portions establish a requisite harmony between several bells. Themethod of forming the profile of a bell, previous to its being east,m which the proportion of the several parts may be seen, is as fol-lows: the thickness ol the brim, Cr, Plate LX.X. fig. 14, is thefoundation of every other measure, and is divided into three equalparts. First, draw the line IiD, which represents the diameter offlie bell; bisect it in F, and erect the perpendicular F f; let DF2nd IIF be also bisected in E and G, and two other perpendicularsGa, be erected at E and G: GE will be the diameter of thef°P or upper vase, i. e. the diameter of the top will be half that ofdie bell ; and it will, therefore, be the diameter of a Hell which wills ouiul an octave to the other. Divide the diameter of the bell, orf m line HD, into 15 equal parts, and one of these will give Ci, thefhickness of the brim ; divide again each of these 15 equal parts*uto three other equal parts, and then form a scale. From this? c ule take 12 of the larger divisions or two-15ths of the whole scalejuthe compass, and setting one leg in D describe an arc to cut thehue Ee in N ; draw N T D, and divide this line into 12 equal parts;
the point 1 erect the perpendicular 1 C = 10, and 0 1 will hedie thickness of the brim= one-15th of the diameter: draw the•me CD: bisect DN ; and at the point of the bisection G erect“'e perpendicular G K = 1 of the larger divisions on the scale.
” ith an opening of the compass equal to twice the length of the* c <de or 30 brims, setting one leg in N, describe an arc of a circle,■Hid with the same leg in K and the same opening, describe ano-uer arc to intersect the former; on this point of intersection as aF e ntre, and with a radius equal to 30 brims, describe the arc NK ;y* d K produced take KB = | of the larger measure of the. scale orIf °I die brim, and on the same centre with the radius 3Gj brims de-^‘ide an arc AB parallel to N K. For the arc BC, take 1:2 ctivi-,'°ns of the scale or 12 brims in the compass; land a centre, andr °ui that centre, with this opening, describe the arc BC, in the^ ai 'ie manner as NK or AB were described. There are various
of describing the arc K p ; some describe it on a centre at, e distance of nine brims from the points p and K; others, as it isj.'-'ne in the figure, on a centre at the distance only of seven brims( roi |i those points. But it is necessary first to find the point p, and° determine the rounding of the bell pi. For this purpose, onj Point C as a centre, and with the radius C 1, describe the arcP”: bisect the part 1, 2, of the line 1) n, and erecting the per-J-odicular pm, this perpendicular will cut the arc 1 pn in m,
^ ‘■‘ch terminates the rounding 1 p. Some founders make thejjvl'iiigs K a third of a brim lower than the. middle of the line„ others make the part C 1 D more acute, and instead ofb r - *'£ tl 1 perpendicular to DN at 1, draw it one-sixth of ajj 1 ” 1 higher, making it still equal to one brim; so that the line [X; 15 longer than the brim G 1. In order to trace out the top-part jutiV ^‘ l ^ e ' n compass eight divisions of the scale or eight brims,
? or > the points N and D as centres, describe arcs to intersectc -' other in 8 : on this point 8, with a radius of eight brims,Or l '0r;t, e the arc N b; this arc will be the exterior curve'of the top ,to : on the same point 8 as a centre, and with a radius equal j
cy^Joruns, describe the arc A e, and this will be the interior It(, p the crown, and its whole thickness will be one-third of jv e nt' ri1 '. P nlr| t S does not fall in the axis ot the bell, a
off. nia >' bit found in the axis by describing, with the intervalVa y n « 011 the centres D and II, arcs which will intersect in M ;
H 11.— N y_ ;j 8i
and this point may be made the centre of the inner and outecurves of the crown as before. The thickness of the cap, whichstrengthens the crown at Q, is about onolhird of the thickness ofthe brim ; and the hollow branches or ears about one-sixth of thediameter of the bell. The height of the bell is in proportion to itsdiameter as 12 to 15, or in the proportion of the fundamental soundto its third major: whence it follows that the sound of a bell isprincipally composed of the sound of its extremity cr brim, as afundamental of the sound of the crown which is an octave to it,and of that of the height which is a third. The particularsnecessary for making the mould of a bell are, 1. The earth:the most cohesive is the best: it must be well ground andsifted, to prevent any chinks. 2. Brick-stone; which must beused for the mine, mould, or core, and for the furnace. 3. Horse-dung, hair, and hemp, mixed with the earth, to render the cementmore binding. 4. '! he wax for inscriptions, coats of arms, &c.5. The tallow equally mixed with the wax, in order to put a slightlay ot it upon the outer mould, before any letters are applied to it. G.The. coals to dry the mould. For making the mould, they have ascaffold consisting of four boards, ranged upon tressels. Upon thisthey carry the earth, grossly diluted, to mix it with horse-dung,beating the whole with a large spatula. The compasses of con-struction are the chief instrument for making the mould : Theyconsist of two different legs joined by a third piece. And last ofall, the founders’ shelves, on which are the engravings of the let-ters, cartridges, coals «f arms, &c. They first dig a hole of a suf-ficient depth to contain the mould of the bell, together with thecase or cannon, underground; and about six inches lower than,the terreplain, where the work is performed. The hole must bewide enough for a free passage between the mould and walls ofthe hole, or between one mould and another, when several bellsare to be cast. At the centre of the hole is a stake erected, that isstrongly.fastened in the ground. This supports an iron peg, cnwhich tiie pivot of the second branch of the compasses turns.The stake is encompassed with a solid brick work, perfectly round,about half a foot high, and of the proposed bell’s diameter. This1 hey call a mill-stone. The parts of the mould are, the core, themodel of the bell, and the shell. When the outer surface of thecore is formed, they begin to raise the core, which is made ofbricks that are laid in courses of equal height upon a lay of plainearth. At the laying of each brick, they bring near it the brandiesof tlie compasses, on which the curve of the core is shaped, so asthat there may remain between it and the curve the distance of aline, to be afterwards filled up with layers of cement, 'l'lie workis continued to the top, only leaving an opening for the coals tobake the core. This work is covered with a layer of cement,made of earth and horse-dung; on which they move the compas-ses of construction, to make it of an even smoothness everywhere. The first layer being finished, they put the fire to thecore, by filling it half with coals, through an opening that is keptshut during the baking, with a cake of earth that has been sepa-rately baked. The first fire consumes the stake, and the fire isleft in the core half, or sometimes a whole dav: the first layer be^ing thoroughly dry, they cover it with a second, third, and fourth;each being smoothed by the board of the compare-, and tho-roughly dried before they proceed to another. The core beingcompleted, they take the compasses to pieces, with intent to cutoff the thickness of the model, ami the compasses are immediatelyput in their place to begin a second piece of the mould. It con-sists of a mixture of eartli and hair, applied with the hand on thecore, in several cakes that close together. This work is finishedby several layers of a thinner cement of the same matter, smooth-ed by the compasses, and thoroughly dried before another is laidon. The first layer of the model is a mixture ot wax and greasespread over the whole. After which are applied the inscriptions,coats of arms, See. besmeared with a pencil dipped in a vessel ofwax in a chafing-dish: this is done for every letter. Before theshell is begun, the compasses are taken to pieces, to cut off ail thewood that fills the place of the thickness to be given to the shell.The first layer is the same earth with the re 3 t, sifted very fine;whilst it is tempering in water, it is mixed with cow’s hair to makeit cohere. The whole being a thin cullis, is gently poured on themodel, that fills exactly all the sinuosities of the tigures, &c. andthis is repeated till the whole is two lines thick over the model.When this layer is thoroughly dried, they cover it with a secondG I ' '