The sheets of a hackling-machine consist of endless leather straps, of about ft. circumference, passing over two rollers, the bottom one of which is the driver, and the top one merely a carrier. The former is 9 in. in diameter, and is furnished with iron bosses on its ends and centre, which have catches on their surface, bearing upon the straps and bars, and thereby causing the sheet to revolve. The bars just mentioned are of iron, the full length of the machine, and 1 in. broad by I in. thick ; they are secured to the straps at their extremities and centres by screws. The hackle-stocks are screwed to these bars, and thus form a revolving sheet of steel pins. On the inside of the end bosses, and on both sides of the centre, grooves or notches, for the reception of the stripper-rods, are east. These rods are plain strips of tough, pliable wood, 1I io. by I in. thick, and sufficiently long to reach from boss to boss. On the extremities, cast-iron ends are riveted. The rods, being pliable, are bent a little in order to get their ends into the grooves of the bosses ; when inserted, they spring back again, and have a certain amount of play. As the roller revolves, they fall forward so as to come into contact with the points of the pins, which are thus stripped of the tow they have combed from the flax through which they have passed. This tow falls upon a " tow-catcher" in close proximity, which, when it has received each contribu tion, deposits it in a box below the machine. The top or carrier-rollers bearing the sheets are adjustable, by which means the pins in working can be set so as to " face up " to those of the corresponding sheet, or to intersect them, as may be deemed most desirable. This system of stripping by means of rods has been re ceived with considerable favour, but experience has shown that in using some sorts of flax it is not perfect. There exudes upon the pins from these sorts a resinous oil, that causes the pins to get clogged with tow, from the failure of the rods to clear it away.
The consequence is that many prefer the older system of the revolving brush and doffer, shown in side eleva tion and section in Figs. 924 and 925 ; but with these also there are difficulties, as they only cleanse one side of the pins. The accumulation of oil upon the latter has, however, been thoroughly obviated by an invention applicable to the stripper-rod system, by R. W. McDowell, Belfast, and which has been secured by Horner. This consists in the introduction of a revolving brush, capable of having the direction of its revolution reversed, by which means, It clears itself and cleans the back of the pins at the same time.
Flax which is hackled in the full length of its fibre is called " long line," and the machine is arranged in its details accordingly, being termed a " long- " or " cut-line " machine. For the finest yarns, however, it is necessary to cut off both ends of the fibre, in order to obtain the regular and even portion of the middle of the fibre, the ends varying greatly from each other and from the middle. The " middle " thus obtained is usually 12-18 in. long ; from very long flax, it is sometimes desirable, in order to avoid waste, to take out two middles, which will each be 9-12 in. in length.
These are called " short middles." At other times, only one end of the flax is cut off ; when this is the case, they are called " long middles." The ends are sent to the card ing-engine, and carded ? into tow. Less labour in roughing is bestowed upon flax which is intended for cutting, as it is simply drawn over the hackle to straighten the fibres, the " pieces" also being made much larger. This is known as " stacking."
The flax is then carried to the breaking-machine, usually called the "cutter," which contains one or two sets of fluted iron rollers, and a circular knife revolving at 600-1000 rev. a minute. The fluted rollers carry the flax in and present it to the action of the cutter, holding it securely until it is cut through.
The sheets should not be driven too quickly, as by so doing, danger is incurred of tearing and breaking the fibre instead of splitting it properly. As to what constitutes a proper speed there is a difference of opinion, but good authorities agree upon the following as affording satisfactory results: About 6 lifts of the head and 20 rev. of the sheet a minute, the finishing-tool containing 8 pins an in., and two rows for six-tool machine, for coarse long-line flax ; 5 lifts of the head, 15 rev. sheet a minute, 14 pins an in., two rows for nine-tool machine, for medium long-line ; 6 lifts of head, 20 rev. sheet, finishing-tool 30 pins an in., two rows for twelve-tool machine, for medium cut line ; 3 lifts of head, 10 rev. sheet, finishing-tool 50 pins an in., two rows for twelve-tool machine, for very fine cut-line.
The hackling-machine is a costly article (2501.-3001.) in the first instance, and expensive to maintain, the wear and tear of the working parts being great, and their frequent renewal a necessity. Fig. 926 shows Cunningham's machine in perspective ; it is made by the firm previously named, and is esteemed in the trade. The "manning" of the machine-room is a comparatively small charge, the labour employed being chiefly that of boys and youths, and consisting of tipplers,. fillers, and changers, whose wages are ls.-1s. 3d. a day.
Dressing and Sorting.—As the flax comes from the hackling-machine, it is held best for it to be drawn through a coarse hackle (a " ten "), broken, and next cleaned over a fine one called a " switch." Highly skilled and experienced men ought to be, and are usually, employed in this task as the assortment of the flax into its different qualities, performed by them, requires experience, intelligence, and quickness of perception to execute it satisfactorily. The coarser varieties of flax are put into the hands of apprentices, girls, and women, as their intrinsic value would not justify the employment of the more costly labour upon them. This is all done by hand. The old and labo rious system of hand-dressing, which required a long training to acquire skill therein, has been so far superseded by machine-hackling that it is now rarely employed. One machine produces as much dressed flax as 20 hand-workers ; four " roughers " are required to supply one machine, and about 6 or 7 sorters to dress the "longs." When the piece has been properly levelled and dressed, it is ready to be transferred to the table, to the bunch in process of formation which in its various qualities it most resembles, where it is carefully placed in such a manner as not to disturb the order in which the fibres lie. But this is done only after it has been what is called " lapped," in which a portion of the end is thrown round the end of the piece in the form of a lap. The pieces are laid so as to overlap each other, but only in such a manner as to contribute to the building up of a square and firm bunch. Each bunch weighs about 20 lb., and is generally tied with four bands ; but in cases where the finer qualities are being treated, they are sometimes carefully put into boxes before being received into the store, where the flax may have to remain weeks, months, and in exceptional cases even a year or two, during which time it ought to be preserved unruffled.