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of the same matter, but somewhat thicker; when this second layer Ibecomes of some consistence, they apply the compasses again, andlight a lire in the core, so as to melt off the wax ol the inscriptions,&c. After this, they on with the other layers oi the shell, bymeans of the compasses. Here they add to the cow’s hair a quan-tity of hemp, spread upon the layers, and afterwards smoothed bythe board of the compasses. The thickness of the shell comes tofour or five inches lower than the mill-stone before observed, andsurrounds it quite close, which prevents the extravasation of themetal. The wax should be tak„-n out before the melting of themetal. The ear of the bell requires a separate w ork, which is doneduring the drying of the several incrustations of cement. It hasseven rings: the seventh is called the bridge, and unites theothers, being a perpendicular support to strengthen the curves. Ithas an aperture at the top, to admit a large iron peg, bent at thebottom ; and this is introduced into two holes in the beam, fasten-ed with two strong iron keys. There are models made of therings, with masses of beaten earth, that are dried in the fire, in or-der to have the hollow of them. These rings are gently pressedupon a layer of earth and cow’s hair, one-half of its depth: andthen taken out, without breaking the mould. Tin 's operation isrepeated 12 times for 12 half-moulds, that two and two unitedmay make the hollows of the six rings; the same they do for thehollow of the bridge, and bake them all, to unite them together,Upon the open place left for the coals to be put in, are placedthe rings that constitute the ear. They first put into this openplace the iron ring to support the clapper of the hell; then theymake a round cake of clay, to fill up the diameter of the thick-ness of the core. This cake, after baking, is clapped upon theopening, and soldered with a thin mortar spread over it, whichbinds the cover dose to the core. The hollow ol the model isfilled with an earth, sufficiently moist to fix on the place, whichis strewed at several times upon the cover of the core; and theybeat it gently with a pestle, to a proper height; and a workmansmooths the earth at top with a wooden trowel dipped in water.
I pon this cover, to be taken off afterwards, they assemble the hol-lows of the rings. When every thing is in its proper place, theystrengthen the outside of the hollows with mortar, in order to bindthem with the bridge, and keep them steady at the bottom, bymeans.of a cake of the same mortar, which fills up the wholeaperture of the shell. This they let drv, that it may be removedw ithout breaking. To make room for the metal, they pull off thehollows of the rings, through which the metal is to pass, before itenters into the vacuity of the mould. The shell being unloadedof its ear, they range under the mill-stone five or six pieces ofwood, abffiut two feet long, and thick enough to reach almost thelower part of the shell; between these and the mould, they drivein wcoden wedges vyitb a mallet, to shake the shell off the modelwhereon it rests, so as to be pulled up and got out of the pit.W hen tins and the wax are removed, they break the model and(lie layer of earth, through which the metal must run, from thehollow of the ring?, between the shell and the core. They smokethe inside of the shell, by burning straw under it, that helps tosmooth the surface of the bell, i hen they pul the shell in theplace, so as to leave the same interval between that ami the core;and before the hollows of the rings or the cap are put on again,they add two vents, that are united to the ring-, and to each other,by a mass of baked cement. After which they put on this massof the cap, the rings, and the vent, over the shell, and solder itwith thin cement, which is dried gradually by covering it withburning coals. '1 hen they fill up the pit with earth, beating itstrongly all the time round the mould. The surface has a placefor the tire, and another for the metal. The fire-place has a largechimney with a spacious ash-hole. The furnace which containsthe metal is vaulted, whose bottom is made of earth, rammeddown; the rest is built with brick. It has four apertures; thefirst, through which the flame revibrates; the second is closed witha stopple that is opened for the metal to run; the others are to se-parate the dross or scoria- of the metal by wooden rakes: throughthese last apertures passes the thick imoke. The ground of thefurnace is built sloping, for the metal to run down.
2. FoUNDERY OF GREAT GuNS, AND MoRTAR-PjF.CES. 'Filemethod of casting these pieces is different from that oi bells: theyare run massy, without any core, being determined by the hollowof the shell; and they are afterwards bored with a steel trepan, that
is worked either by horses or a water-mill. For the metal, parts,proportions, &c. of these pieces, see Gunnery.
3. Foundery of Letters, or Casting of Types forPrinting. In the business of cutting, casting, 8, r c. letters forprinting, the letter-cutter must be provided with a vice, hand-vice,hammers, and tiles of all sorts such as watch-makers use; alsogravers and sculptors of all sorts, and an oil-stone, &c. suitable andsizeable to the several letters to be cut: a flat gauge made of boxto hold a rod of steel, or the body of a mould, &e. exactly per-pendicular to the flat of the using tile: a sliding gauge whose useis to measure and set off distances between the shoulder and (lietooth, and to mark off from the end, or from the edge of the work,a face-gauge, which is a square notch cut witli a tile into the edgeof a thin plate of steel, iron, or brass, of the thickness of a piece ofcommon tin, whose use is to proportion the face of each sort ofletter, viz. long letters, ascending letter?, and short letters. Sothere must be three gauges, and the gauge for the long letters isthe length of the whole body supposed to be divided into 42 equalparts. The gauge for the ascending letters Roman and Italic arcfive-sevenths, or 30 parts of 42, and 33 parts for the English face.The gauge for the short letters is three-sevenths, or 18 parts of 42of the whole body for the Roman and Italic, and 22 parts lor theEnglish face. The Italic and other standing gauges are to measurethe scope of the Italic stems, by applying the top and bottom ofthe-gauge to the top and bottom lines of the letters, and the otherside of the gauge to the stem; for when the letter complies withthese three sides of the gauge, that letter has its true shape. Thenext care of the letter-cutter is to prepare good steel punches, welltempered, and quite free from all veins of iron; on the face ofwhich he draws or marks the exact shape of the letter with penand ink if the letter be large, or wilh a smooth blunted point of aneedle if it he small; and then with sizeable and proper-shapedand pointed gravers and sculptors, digs or sculps out the steel be-tween the strokes or marks he made on the face of the punch, andleaves the marks standing on the face. Having well-shaped theinside strokes of his letter, he deepens the hollows with the sametools; for if a letter be not deep in proportion to its width, it will,when used at press, print black, and be good for nothing. Thiswork is generally regulated by the depth of the counter-punch.Then he works the outside with proper tiles till it be (it for thematrice. Before wc proceed to the sinking and justifying of thematrices, we must provide a mould to Justify them by. See PlateEXX, fig. 13 and 10. Every mould is composed of an upperand an under part. The under part is delineated in fig. 15. 1 l' c
upper part is marked tig. 10, and is in all respects made like theunder part, excepting the stool behind, and the bow or spring alsobehind; and excepting a small roundish wire between the bodyand carriage, near the break, where the under part hath a smallrounding groove made in the body. 'Phis wire, or rather half-wire, in the upper part makes the nick in the shank of the letter,when part of it is received into the groove in the under part.These two part.-, are so exactly fitted and guaged into one another(vis. the male-gauge marked c in tig. Hi, into the female markedg in fig. 15,) that when the upper part of the mould is properlyplaced on, and in the under part of. the mould, both togethermake the entire mould, and may be slid backwards for use so far,till the edge of either of the bodies on the middle of either car-riage comes just to the edge of the female gauges out in each car-riage: and tlrey may be slid forward so far, till the bodies on ei-ther carriage tou< h each other: and the sliding of these two partsof the mould backwards makes the shank of the letter thicker, h c 'cau-ethc bodies in each part stand wider asunder; and the slidingthem forwards makes the shank of the letter thinner, because thebodies on each part of the mould stand closer together. The partsof (he mould are as follows: viz. a, The carriage. !>, The body-c, The male gauge, d e, The mouth-piece, f i,'1 he register-g, The female gauge, h, The hag. a a cm, The bottom-pbd*'b h b, 'i'he wood on which the bottom-plate lies, c c c, dmouth, d d, d lie throat, c d d, d he pallat. J) d he nick-g g, d he stool, h h, d'he spring or bow. d’lien the mould nu' sbe justified: and fust the founder justifies the body, by caslh'Sabout 20 proofs or samples of letters; which are set up in a con 1 'posing stick, wiih a'l their nicks towards the light hand; and the 1 ’by comparing these w ith the pattern-lettcs, set up in therame nud^ner, he finds the exact measure of the body to be cast. He also tu^