Shearing the Bars.—This rough bar is therefore, immediately it has passed through the rolls, and while it is still red hot, put between the jaws of a pair of shears, worked by the engine, and cut into lengths of about a foot each. A pair of shears for this purpose is represented in the engraving of the great at page 712, by to which the reader will readily comprehend our explanation of them. That portion of the shears marked g g g, is one mas sive casting, and is fixed to the ground in the most solid and substantial manner. The cutting edge of the lower chap at k is formed out of a stout steel bar ; it lies in a rebate, and is therein fastened by screw bolts. The chap of the upper shear i i is similarly provided ; this shear is the movable one, and has its joint or centre of motion in the upright at g. By the revolution of the drum e, it carries round with it an eccentric or solid crank k, to which is jointed a stout iron bar 1, which bar being jointed at its other end to the upper shear, communicates its own vibratory motion to the shear, and makes it cut at each alternation of the stroke or revolution of the drum. To prevent the steel edges of the shears from being softened by the contact of the hot bars, a small stream of water is made to flow over them constantly, brought on by a small pipe, or other suitable channel, and regulated by a cock. The bars as they are cut, fall into an iron barrow or truck, in which they are wheeled _away to the Filen Piling.—The piler piles the pieces of the rough bar together in the manner shown in the annexed cut, putting as many upon one another as will form a bloom or a finished bar of the size and weight required. The piles are then taken or deposited in a convenient situation for being put into— The balling or reheating Purnace.—This furnace is in no essential respect dif ferent from the puddling furnace already described ; but the men who work them are usually called "bailers." Balling.—With an iron instrument of the shape of a baker's peel, the bailer places each pile on the bed of sand prepared to receive them, taking care not to disturb them, so as to cause any of the pieces to project beyond the rest, as these projecting pieces would, in consequence, be sooner heated, and sustain a severer action of the fire than the others, causing those exposed parts to burn or waste, and the whole mass to be deteriorated in tenacity. The number of piles put into the furnace is regulated by their size, in order that when they are sufficiently heated they may be quickly discharged ; and as large heavy bars take longer to roll than small light ones, a less number of large piles are put into a furnace in making large bars, than of small piles in making small bars. NotwithstandinF the bailer arranges his batch so that the piles may be com pletely heated in succession, he exercises his judgment upon them with his eagle-like eyes, as to which bloom is in the most forward state. The bailers' proceedings are likewise regulated by the state of the other balling furnaces of the work, whose products are successively worked off. if a bailer keeps his iron too long in the furnace, it is thereby rapidly wasted and' deteriorated ; on the other hand, he must be ready to a minute, that the rolls may be constantly at work, and that the power of the engine may not be wasted. The blooms that are now taken out of these reheating furnaces, are presumed to be of a quality adapted to the manufacture of common bar-iron, of which there is a very extensive variety of forms; but the great bulk consists of three kinds, namely, flat, square, and round, the latter being usually termed bolts. Of the three last-mentioned classes, there are very numerous sizes, as will be seen on reference to the tables subjoined to this article.
Variety of Rolling Apparatus.—For the manufaCture of so extensive a variety, a great number of rolls is required in an iron work. The stock of these ponderous tools, in some works, consists of upwards of a hundred pairs; and there are commonly from ten to twenty pair of standards (fixed in the most firm and solid manner that art is capable of) ready for their reception. A sufficient example of this kind of mechanism for making flat bars has already been given at d e fg, in the cut at page 773 : in the illustration which follows, the rollers for making round and square bars are shown. These rolls are called finishing rolls, for the bar, previously to being brought to them, is passed through several grooves of a pair of roughing rolls, which are of greater diameter than the finishing rolls, and furnished with larger grooves. In these last-mentioned, the
bars are reduced to nearly the intended size, and they are then run through two or three grooves of the finishing rolls ; each time that a bar is passed through, whether round or square, it is turned a quarter round to take off the burr or fin, formed at the junction of the rollers, and through the last hole it is usually passed twice, by which its figure is perfected. The effect of the piling and reworking the iron, as just described, has been to weld the several layers of the pile together, which thus become one solid mass, possessing a fibrous tex ture and an increased toughness ; and during the operation, many of the impurities that the iron had retained are expelled. In rolling flat bars, the treatment is different from that of square and round; the pile is never presented to the rolls with the edges of its layers upwards, but always with their flat sides horizontal ; for were the bar rolled upon the edges of the layers, the welding would probably be very imperfect, and the bar comparatively weak. Each bar after it is completed in the rolls, is taken by two boys with tongs, who first put the marks on with steel punches ; they then present its extremities, which are usually ragged and uneven, to be cut off by a pair of shears that are constantly opening and shutting by the action of the engine ; the boys then take the bar, and lay it along a sohd cast-iron bench, perfectly flat, and having a straight edge on one side ; and as the bar is still hot, they easily make it per fectly straight by a few blows with wooden mallets.
Process of Rolling—Defects and Improvements.—To give the reader a clear insight into the mode of working a bar through the rolls, it appears to be necessary partly to repeat what has been before but imperfectly noticed. A bar of iron, as it passes through each successive groove of a pair of rolls, is received on the opposite side by two men, one of whom draws it out by the end with a pair of tongs, and the other supports it by a lever to prevent its making too sudden a bend ; and when the bar is through, these men pitch it back again over the top roll for it to pass through the next groove ; and this operation is repeated until the bar is reduced to the required size. Now it must be evident upon reflection, that this returning of the bar over the rolls occupies about as much time as the actual rolling ; consequently that the iron becomes cooled in proportion, harder, and requires more power to roll it ; that the workmen have a very severe labour to perform, and are all the while exposed to a scorching heat. These defects in the ordinary process of rolling forcibly struck the writer several years ago, when he proposed two methods of continuous rolling, by which it was estimated that the manual labour would be greatly reduced, the personal inconvenience diminished, the cost of the machinery lessened, and one-half of the power of the engine saved. The first of these plans was to place a series of pairs of email rollers (that is, short in their axes) one before the other, so that the bar might pass in one continued straight line, from groove to groove, until finished of its intended dimensions. This plan is explained by the annexed diagram ; a a, b b, and c c, represent the transverse sections of three pair of rollers, with grooves of different depths ; the bar is supposed to enter at d, and by passing through the rollers a a to be reduced to the size e, where the bar slides upon a form 14, guided thereon in a straight line by a fur row of the shape of the bar, direct into the grooves of the rollers b b; the bar of the size of e is here reduced to that of f, lying on another form /a, which con ducts it through the rollers e e, and is thereby further reduced to the size of g, or any other that may be required by a suitable extension of the apparatus. By this method it was considered that a bar would be rolled in about one-third the usual time ; that the manual labour would be reduced to a trifling amount; and that not one-half the usual power required of the engine would be absorbed. The latter advantage results from the celerity of the operation ; for as the iron is much hotter, it is much softer, and requires a less amount of force, even during the diminished time taken up by the process ; but the most im portant advantage is, that a beUer bar is thereby made ; when the maxim to " strike the iron while it is hot," has thus been duly attended to, the bar, instead of being cracked at its edges or otherwise unsound from being rolled when too cold, will be uniformly solid and of a more perfect form.