another method, to be hereafter explained, of cutting such a screw. Again referring to Fig. 125, two forms of back poppit are shown, E and F. In the first, the centre point advances and recedes on turning the screw without itself turning round. The point T, shown separately on Fig. 126, is also removable, and others can be substituted in place of it. This form of poppit is in all ways the best, especially when drilling in the lathe is practised. It is, however more costly than F, which has simply a pointed screw passing through it which can be clamped by the small bolt F. The extreme end, however, can, if preferred, be made removable, in which case it will be sufficiently serviceable, and may fairly take the place of the cylinder head E. These poppits, and likewise the hand-rest H, are secured by bolts screwed into them, at the lower end of which a thumb-nut works, as seen in the drawing. The holt passes through the centre of the holding-down plates, of which the face of one is seen at X. The upper part of the rest, called a T, slides up and down in the upright socket R and can be fixed at any height by the screw at the side. There are long and short Tees—those for metal turning being made flat at the

top, as Fig. 127; those for wood generally have the form of Fig. 128, and should, as it were, lean over, so that the edge on which the tool rests, and along which it traverses as the work proceeds, can be placed as close as possible to the piece to be turned. If the latter is of great length, two rest sockets are used, and the long T requisite in such a case has two legs or tangs. M M are crank chains (a kind of flat broad chain specially made for this purpose); they pass over the cranks and round two rollers on the treadle, which are seen in Fig. 129. This is the best way to connect the treadle with the crank; as the movement will be sinooth and easy, a mere hook will, however, answer the purpose. The pointed screws S S, of hard steel, support the axle, the holes in

the latter being drilled as before shown in Fig. 126. Another superior method is to use friction rollers, Fig. 130, where a a represent two small brass wheels, about 3in. across the face, and half an inch broad, their edges at least turned up bright. These are mounted on their pivots so as to overlap a little, and the ends of the lathe axle are simply laid upon them as in the figure, its weight keeping up a constant rolling contact as it revolves. This is by far preferable to the sustaining screws, rendering the work of the legs almost nominal. The ends of the axle must be turned with a shoulder to prevent end motion; and it is convenient to carry it through the standards so as to be able to afford, outside the latter, an extra pulley for connection with any special shaft or overhead motion. In many lathes the axle is not cranked but straight, a crank being then keyed on at each end outside the

standards to take the crank chains. To carry this, which is a neat plan, into effect, it is necessary to let the ends of the back bar of the treadle pass through bearings in the feet of the standards, and to attach outside the latter arms to receive the crank chain pulleys. There is no practical difficulty in this, and the straight axle is more desirable, besides the advantage afforded of removing the crank chains out of the way of the legs. In respect of this last point, moreover, it would be better if possible to get the fly-wheel also outside the standards, or, at any rate, to move it back so as not to project at all in front of the lathe. In some old French lathes, the fly-wheel was placed overhead upon a strong pillar carried up by the left-hand standard, or forming an extension of the latter; this gives a clumsy top-heavy look to the lathe; otherwise the purpose is sufficiently answered of moving the large wheel out of the way, and with it the lathe cord, so that (as in a machine lathe) the whole bed is clear from end to end. There is no reason why the crank and fly-wheel should occupy the place usually assigned to them, as

they might be advantageously mounted on a separate stand, independently of that which supports the bed of the lathe, provided the treadle be still brought into a convenient position. It is only for the sake of handiness, in other respects, that the crank axle is placed below the bed, and that the lathe may be complete in one frame. If, for instance, the fly-wheel were outside, as Fig. 131, and the

mandrel turned round as shown, on special occasions it would be

possible to turn a small table, or any article much larger than could otherwise be managed, but the bed must slightly overlap the standards to enable the poppit to be secured and also the rest; the latter however might be contrived somewhat differently for such exceptional cases. There are one or two drawbacks never

theless to the position of the wheel here shown. In the first place, though the wheel and cord are out of the way, the standard now takes up a similar position as regards the turner, and the only really practical method of overcoming all drawbacks is to carry the lathe-cord from the wheel outside the standards to a shaft overhead and thence down again to the mandrel. The additional friction of the shaft through its bearings has indeed to be overcome; but if friction wheels are used on the crank axle, and the parts are all well made with hardened steel screws and well-drilled axles, the

advantages of such a plan will be great, as the mandrel-head can be placed anywhere upon the lathe bed or faced either way as most convenient, and the overhead motion answers for purposes of screwcutting and ornamented work when required. An illustration of such an arrangement is consequently given in this place, which may, of course, be nevertheless modified if desired. The whole apparatus, too, may be simply beyond the bed instead of overhead, nd thus can be attached to the frame of the lathe itself. This is the construction represented in Fig 132. B B are uprights of flat

iron bar, made into a frame by cross stays E F, and hinged at the bottom to a frame G G H H, the latter being secured to the bed or backboard of the lathe. K K are curved steel springs, tending to cause the upper frame to lean backwards, thus keeping up the tension of the lathe cords. ADC are three pulleys or cones, of which A is fixed to take the cord from the fly-wheel of the lathe. D and C should be free to slide upon the bar, on and with which all the pulleys revolve, and may thus be put in any position upon the same, and clamped by a screw when in place. The distance BB should be that of the length of the lathe-bed, the height about two feet, and the whole should be carefully and strongly put together. For special purposes the pulleys may at any time be replaced by others of a larger size. It is just possible that the cord from the right-hand pulley may come in the way of the work when used to convey motion to the screw of the slide rest for self-acting turning and screw-cutting, but this will rarely happen. It may be prevented by having long slots in the part HH, so that the frame can be bodily shifted further off or nearer the lathe-bed, and it would then be clamped by large-headed bolts and nuts passing through the backboard. It is not necessary to detail other modes of arranging the overhead apparatus of lathes, as they vary according to the tastes of the makers. All that is necessary, is to have a method of keeping the cords tight, either by balance weights or springs. The pulley C is also replaced by some makers by a long roller, so that the cord may be placed at any point over the work to be turned, without the necessity of .shifting the pulley. It is a good plan, but sometimes the cord may slip on the smooth surface of such roller, hence it is also not unfrequently grooved.

A great deal of the ease with which turning is carried on depends upon the chucks used, for in many cases it is a work of time and trouble to arrange a plan by which the piece to be turned can be satisfactorily secured to the mandrel. Wooden chucks are of necessity often used, as already stated, being simply blocks of the required size screwed to the mandrel and afterwards hollowed out to receive the work. These have one advantage, namely, the