Imágenes de páginas
PDF
[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][graphic][graphic][merged small][merged small]

EDINBURGH:
PBINTED DY JOHN BROWN, ANCHOR CLO'B,
FOR THE PROPRIETORS,
AND sow BY ALL THE BOOKSELLERS IN THE UNITED xmcnmz.

[graphic][merged small][merged small]
[blocks in formation]

x dlWsPn &I. 11] .

JXFUHJ

'un n

L;

[graphic][merged small][graphic][graphic]

F O U
FOUNDERY.

Ar the conclusion of our last Volume, (see page 7'S,) we inserted this word in its proper order, 'itli its different definitions, but had not sufficiert room remaining in that volume to insert the various branches of this art, in the complete

manner, which an article of such importance required.

1. OUNDERY or Brus. The metal, it is to be observed, is different for bells from what

is for flames ; there being no tin in the latter; but there is a 5th, and sometimes more, inthe bell-metal. The dimensrons of the core and the wax for bells, if a ring of bells especially, are not lett to chance, but must be measuted on a scale, or diapaL-n. which gives the height, aperture, and thickne-ss. ne-cessary for the several tones required. lt is c-o the wax that the several mouldi-ngs and other or'aments and inscriptions, to be represented in rel-e-'o on the outtide of the bell, are formed. The clappen' or tongue is not properly-a part os the beil. but is furnished from other hands. In Europe, it is usually of iron, with a large knob at the extremity ; and is suspencled in the middle of the bell. ln China, it is only a huge wooden mallet, struck by force of arm againlt the bell; whence they can have but little of that consonancy so much admired in some of our rings of bells. The Chinek have an extraordinary way of increasmg the sound of their bells, viz. by leaving a hole under the canoon; which our hell founders would reckon a defect. The proportion: of our bells (slier very much from those of the Chinese, as Wl as their srzes. See BELL, No I, t 5. In ours, the modern propertions are, to make the diamele' '5 time: the thickness of the brim, and the height 13 times. The parts ot' a bell are, 1. The founding bow, terminated by an inferior circle, which grows thinner and thinner. 2. The brim or that part of a bell whereon the clappen' strikcs, and which is thicker than the rest. 3. The outward sinking of the middle os- the bell, or the point under which it grows wider to the orim. 4. The waist or furniture, and the part that grows wrder and thicker quite to the brim. 5. 'she upygsc, or that part which is above the waist.

6_ The pallet which supports the (taple of the clappcr within. 7. The bent and hollow branches

Vol" x, Pan? l.

[blocks in formation]

iron keys, whereby the bell is hung up to the bean), which is its support ano counterpoise, when rung out. The business of bell-sphndery is reduciblc to three particulars. 1. The proportion of a bell, 2. The forming os the mould. And, 3, The melting of the metal. There are two kinds os proportions, viz. the simple and the relative ;, the former are those proportionaonly that are between the scveral parts of a bell to render it sonorous: the relative proportions establish a requisite harmony between several bells. yt'l'lte me:hod ofsorming the prohle of a bell, previous to its being cast, in which the proportion of the several parts may be seen, is as follows: the thickness of the brim. Cr, Hare CLV.j£e. ii. is the foundation of every other measure, and is dnided into three equal parts. First, drawsithe line til), which represents the diameter of the bell: bisect it in F, and erect the perpendicular Ft; let DF and HF be also bisected in E and G, and two other' perpendrcnlars E e, G a, be erected at F and G 5 GE will be the diametcr of the top or upper vase, i. r. the diameter of the top will be halt that of the bell; and it will. therefore. be the diameter of a bell whieh- will sound an octave to the other. Divide the diameter of the bell, or the line l-lD, into 15 equal parts, and one of these will give Cr the thickness ot the brim: divide again each of these 15 equal parts into three other equal.parts, and then form a scale. From thisscale take 12, of the larger divillons or two 15ths of the whole scale in the compass, and setting one. leg in D describe an arc to cut the line Ee in N; draw ND, and divide this line into r: equal parts; at the point 1 erect the perpendicular 'C = ro, and Ci Will be the thicknrss of the brim = one rzth of the diameter; draw the line CD: bisect DN; anct at the point of the bisection 6 erect the perpendicular 6 K = rk of the larger divisions on the seale. With an Opening of the compass equal to twice the length of the scale or 30 brims, setting one let: in N, describe an arc os a circle, and with the same' leg in K and the same opening, describe another are to intersect the t'ormer: on this point of intersection as a centre, and with a radius equal to 30 brims, describe the arc NK; in 6 K produced take KB = + os the larger measure of the scale or f of the brim, and on the same centre with the

A radluz radiu' to; brims describe an arc AB parallel to NK. For the arc BC, take '2 divisions os the scale or 11 brims in the compass; find a centre. and from that centre, with this opening. describe the arc BC, in the same manner as NK OrAB n'ere described. There are variriuo ways os ctscribing the arc Kp 3 some describe it on a centre at the distance of nine hrims from the points p and K; others, as it is done in the figure, on a centre at the distahce only of then' brims from those points. But it in necessary first to find the point p, and to determine the rounding of the bell p t. For this purpose. on the point C as a centre, and with the radius C r, describe the arc r p n; hisvct the part t, a, of the line D n, and erectin; the perpendicular p m, thin perpendicular will cut the are 1 p n in m. which terminate' the rountling 1 p. Some founder' makethe bendines K a third of a btim lower than the middle of the line DN; others make the part C t D more acute, and instead of making C 1 perpendicular to DN at t. draw it one 6th of a hnm higher, making it still equal to one brim; so that the line t D is [one 'rthan thehrimC i. ln order to trace out the zop part Na, take in the compass eight division-i of the scale or 8 hrims, and on the points N and D as centree. describe arca to inn-'sect each othel in 8: on this point 8,- with a radius of eight brims, describe the. ark N'o; this arc will he the exterior curve os the top or crown; on the sime point 8 as a centre, and with a radius equal to 7+ brima. describe the arc A e, and this will be the intcrior curve of the crown, and its whole tliirrkness wit' he one third of the brim. As the point 8 does not fall in the axia of the bell, a centre M may be found in the axis by describing, with the interval of 8 brims on the centre' D and 1', are' which will intersect in M; and this point may be made the centre of the inner and outer curves os thi- crown a' before. The thick-test of the cap, which strengthens the crown at Q, is about nue third of the thick-nest of the brim; and the hollow branches or ears about one lixth of the dianieter os the bell. The height/os the bell is in proportion to iti' diameter as t), to re, or in the proportion os the sunrlamenta] sound to its 'hird major: whence it follows that the sound of a bell in principally composed of the sound os its extremity or hrim, as a sundamental of the sound os the crown which is an octave to it, and of that of the height which in a third. The particulars necessary for making the mould os a bell are, r. The earth: the most cohetive is the best ; it must be Well ground and lifted, to prevent any chinka. 1. Brick stone; which most be used for the mine, mould, or core, and for the furnace. 3. Horse-dung, hair. and hemp, mixed with the earth. to render the cement more binding. 4. The wax for inscription', coata of arms, &c. 5. The tallow equally mixed with the wax, in order to pot a slight lay 'it it upon the outer monld, h-xt'ore any letters are applied to it. 6. The coal' to dry the monld. For makimz the mould they have a scaffold conmting of four board', ranged upon tressela. Upon th s they carry the eatth, fisOsK-Y diluted, to mix i' wi'h burst-dung, beating the whole With a large 'z-it-i'a. 'The crimpassea of construction are the c-uet' instrument tur making the monld: They

consist of two dificrt-v logs, joined by a thlrd piece. And last of all, the sounders shelves on which are the engravings of the letters, cartric', e-c, coats of arms, &e. 'l'hey first dig a hole of a sufficient depth to contain the monld of the bell, together with the case or eannon, under ground ;

rahd about six inches lower than the terreplain,

i strongly fastened in the ground.

vihere the work is performed. The hole must be.wide enough for a sree passage between the mouid and walls os the hole,- or between one mouid and another. when several bells are to be cast. At the centre ofthe hole is,a fiakc erected, that i, This support: an iron peg, on which the pivot of the second branch os the compassesturns. The stake is eneomp assed with a solid bricl: work, perfectly round , about half a foot high. and of the proposed bell's diameter. Thi= they call a mill-stone. The parts of the monld are, the core, the mode] of the bel', and the shell. When the outer sursace osthe core is formed, Lhey begin to raise the corn, uhich is made os brieks that are laid in coun'es us equal height upon a lay of plain earth. At the laying of each brick, they bring near it the branches of the compasses, on which the curve os the eore is shaped, so as that there may remain between it. and the curve the distance of a line. to be asterwards filled up with layers of cement. The work in continued to the top, only leaving an opening for the coals to bake the core. 'I his work is covered with a laycr of cementl made of earth and horse-dung: on which they more the compasses of construction. to make it of an even smoothncse every where. The first layer beingv finished, they put the fire to the core, by filling it halswith coals, through an opening that is kept shut during the baking, with a cake of earth that has been separately baked. The first fire cnnsumes the stake, and the fire is left in the cure half or sometimes a whole day: the first layer being thoroughly dry, they cover it with a second, third, and fourth: each being smoothed by the board os the compasses, and thoroughly dried before they proceed to another. The core being completed. they take the eompasses to pit-ers, with intent to cut offthe thickness of the model, and the compasses are immediately put in their place to begin a secord piece of the monld. lt consists os a mixture of earth and hair, applied with the hand on the core. in several cakes that close together. Thi' work is finished by several layers of a thinner cement of the same matter, smoothed by the compasl'es, and thoroughly dried before another is laid on. The first layer ofthe model is a mixture of wax and grease spread over the whole. After which are applied the inseriptions, coats of arms, &c. besmeared with a pencil dipped in a vessel of wax in a chafing dish: thin is done for every letter. Before the shell is begun, the compasses are taken to pieces, to cut off all the wood that fills the plaee of the thickness to be given to the shell. The first layer i\ the same earth with the rest, stfte' very fine; whilst it is tempt-ring in water. it is mixed with cow's hair to make it cohere. The whole being a thin cullie, ia gently poured on the mculnl, t at lilis exactly all the linuosi'ies of the figtnrs, &e. and this is' repeated till the whole is two lines thick over the made', When this

« AnteriorContinuar »