The essential parts of such a construction will be understood from [fig. 438.], though the fluted rollers are absent. The flax a, b, is held by the hand, or in a kind of clamp. The cylinder is partly covered with a curvilinear plate of iron c, d, which serves to sustain the flax, and to guide it in circular tresses round the periphery of the heckle. At the beginning it is placed near b, when the tips of the flax are only presented to the heckles; during the working the shield is continually drawn back in the direction from d to c, and thus lets the operation be performed upon the remaining part of the flax.
First operation; the conversion of flax into ribands or slivers.—This is effected by subjecting the flax to a series of advancing gills or heckle-teeth, and at the same time drawing out its fibres by means of rollers. [Figs. 439], [440], [441], show the outline of the construction of a machine for this purpose. Here two rows of heckles are placed alongside of each other, though only one of them be shown in the ground plan, [fig. 440.], in order to allow the parts beneath the other to be seen. The flax is placed in the sheet iron channels a a, by laying down one handful after another, so that the points of the second strick reach to only the middle of the first, and thus preserve a uniformity of thickness in the feeding. This process is necessary, since, as every one knows, the heckled stricks are always thick in the middle, and thin at the ends. The flax being introduced between the rollers b and c, is drawn out by their agency, and at the same time subdivided by the heckles d, between whose teeth the pins of the roller e press it down. At the rollers f3 it is loosened from the heckles by the transverse bars which rise from the springs g, after which it is seized by the rollers h i, and drawn again. A little beyond these rollers, it runs through a funnel l, in order to gather the fibres together; in front of these rollers the slivers from both rows of heckles are united, and proceed in one riband through that polished brass funnel; the rollers m n extend this riband, pressing it gently together, and then let it fall into a tin can. The union of the two slivers contributes to the uniformity, since the irregular thicknesses are thereby compensated. The diameter of the roller c, is equal to that of each of the cylinders f, f1, f2, f3; and the whole five move with equal velocity. The same correspondence exists between the rollers n and i. Thus the sliver of flax is not stretched either by its passage from e, upon the heckles, nor between i and n, but solely in passing from the heckles to the rollers i h. The heckle teeth of this machine do not stand perpendicularly, but are bent somewhat backwards; so as to retain the flax more firmly. The revolving cylindrical brush o, is placed over and a little in front of the pressing roller h, in order to take off all the filaments of flax adhering to their circumference, and to toss them onwards where they may again unite with the slivers. For the sake of perspicuity, the rollers h, and those brushes are left out in [fig. 440.], but the latter are particularly shown in [fig. 442.], while a portion of their axis q, is however shown in [fig. 440.] The pressure of the cylinder h, upon the cylinder i, is produced by the weight r, [fig. 439.], which hangs upon the lever s; the lever pulls down at t, a vertical rod, whose upper hook-shaped end embraces the axis of h in the middle of its length.