MANUFACTURES.

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ManuCac- and C being large blocks of stone laid down to receivetures - and support the cast iron frames; to secure these to

the stones, iron pins with screws cut on them are firstlet into the stones and passed through holes cast in theseveral plates, to which they are then firmly screweddown by nuts. D E are two standards for carrying thewinch or handle F, intended to be worked by three men.Gr is a stroll n ' double cast iron frame, intended to supportthe bevelled°wheel which works the horizontal bevelledwheel I; through the centre of this wheel slides thedrill shaft, so that it may descend freely through it, andfollow its work as the drilling proceeds ; in some casesthis shaft is square, but it is more commonly cylindrical,with a recess to take a feather left in a cavity of the wheel’scentre. In the collar L the drill shaft also passesfreely, and the latter is united above with a rack, as seenin the drawing. This rack is worked by a small pinionm, by means of a wheel fixed on the same axle with it,but being on the other side of the frame, is not seen inthe elevation; over this wheel passes an endless chain,which hangs down, so that a man pulling on it mayraise the rack and drill shaft to any required height, atwhich it will be supported by means of the ratchet wheeland a spring pall, seen on this side of the frame at M.

N N is an iron stage, which may be raised to any re-quired height and secured there by means of holes leftin two standards O O, one only of which can be seen inthe figure, the other being between the two sides of theprincipal frame, but its situation is shown by the dottedlines. P is a pit sunk in the floor of the building forthe convenience of turning downwards any long arm orother part of the ironwork which may be required tobe drilled by the engine, such as the iron knees of ships,and various other heavy ironwork; when, however,it is not required for use, it is covered over by flooringboards, and the engine then assumes a very simple andcompact form. W is a fly wheel to give a steadiness to themotion, and is what the workmen call loaded with woodon the circumference towards wheie the handle is placed;that is, square holes are left in its r.m, which are filledwith wood ; this is intended to remove a weight towardsthat part equal to the crank, so that the latter may bebalanced by the other side of the wheel, and therebystand in any position in which it is placed, instead of al-ways descending to its lowest position, as it would dowithout this or some similar contrivance The drill His inserted in a socket in the bottom of the shaft, and isthere secured by a bolt, and may of course be shiftedand changed according to the size which the work im-mediately in hand may require. When the hole is verylarge, as for instance two or three inches, a hole of a lesssize is first drilled, and then a tool is used instead of adrill to enlarge it, fitted with a cutter on each side, andthis cutter is changed as the work proceeds till the pro-per dimension is attained.

The drilling engine here described is one at presentbeing erected in his Majesty’s Dock-yard at Woolwich,constructed by Mr. Kingston, an ingenious millwrightof Portsmouth. In the same establishment are twoother more powerful engines for drilling which areworked by a shaft turned by the steam engine, whichare in their principle of action nearly the same as thepreceding, except that the principal shaft driven by thesteam engine is much higher, so that the drill receivesits motion entirely from above ; and the rack by whichit is elevated is also considerably higher, and works be-tween the two parallel sides of a cast iron frame, but

the drill is elevated, and the pressure brought upon it Machineiywhen at work by an endless chain, as already described,

(332.) Engine for cutting files. —This is rather a desi- File cuttingderatum in Mechanics than one in actual existence, atleast in that degree of perfection which the process re-quires, although many very ingenious men have devoteda good deal of time and attention to the subject; amongstothers, the late Mr. William Nicholson, editor of theScientific Journal , so well known under his name.

Another engine also for this purpose is described inthe American Philosophical Transactions , as also inGregory’s Treatise on Mechanics , and in other English Works. Generally, however, it is considered that thebest files are those cut by hand ; and it will, therefore,be more satisfactory to the reader to be informed of thenature of the manual process, than for us to enter uponthe description of a Machine which, however ingeniousin itself, is not generally applicable to the purpose forwhich it is designed. A file which is of the same breadthand thickness throughout, may certainly be cutbyeitherof the engines above referred to, the same degree ofpercussion being required for every tooth ; but if the filebe conical, it is obvious that a very complicated enginewould be requisite, and great delicacy ot operation to cutall round with the precision it may be effected by hand.

A chisel also employed in this process is very liable tochip or to get otherwise out of order, which the workmanimmediately feels, and makes the requisite repairs ;whereas with the engine such an occurrence wouldnot be detected till the file was examined. In cuttingby hand, the workman sits on a block of such a heightas is found convenient, placing himself astride as onhorseback ; he is also, as in that case, furnished with aleathern strap, answering as stirrups, which strap, passingover each end of the file, retains it in its place by thepressure of his feet; he then, with the chisel in onehand and the hammer in the other, raises the teeth witha dexterity obtained by practice which is very astonish-ing. In cutting the first side of the file, it is rested onan iron anvil, but when the second side is cut, a pieceof thin lead is laid on between the anvil face and file, inorder not to damage the side already cut. Great careis necessary in preparing the edge of the chisel, whichis in the first place hardened and tempered at a yellow-ish-brown heat; the edge is next ground very true, andafterwards finished on a turkois stone with oil; it is notmade very sharp or fine, the bottom of the cut or toothrequiring to be rather open, to prevent the file fromclogging with the substance filed ; the edge is, however,required to be very smooth, in order to its slipping easilyalong the surface during the operation ; for it is simplyby the feeling that the process is conducted, and if theedge were not very smooth, it would be impossible topreserve that uniformity in the distance of the teeth whichis observable in a well-cut file. This sliding is also as-sisted by a little grease. All these motions are per-formed with astonishing rapidity : first the chisel, thenthe hammer, to the amount of between two and threehundred strokes, making as many teeth in a minute ;in the larger files, however, which require heavier blowsand deeper teeth, the number cut per minute is of coursenot so great.

Files receive particular denominations; first accordingto the rate of their teeth, and secondly according totheir shape. Files of the very coarsest sort are calledrubbers, and the next in order to these are called roughfiles, the next are called bastard cut, the next second