The position of the turner using the pole lathe is fatiguing and not very secure; he is compelled to stand continually upon one leg, while at the same time he alternately raises the other rather high, and then depresses it with some force; and both hands being exclusively occupied with the tool, he requires the back rest to steady and support his body.
Moxon describes the back rest fig. 20, in the most intelligible manner, he says - "Of the seat - These Bearers reach "in length so far inwards, as that they may be capable to bear "the Seat so far off from the Lathe, as is the Diameter of the "Work they intend to Turn in the Lathe, and also the bulk of "the Workman that stands between the Lathe and it, may be "contained. It is not called the Seat because it is so; but "because the Workman places his Back against it, that he "may stand steddier to his Work, and consequently guide his "Tool the firmer and exacter" (page 182).
The back rest, thus quaintly described and necessary to the pole lathe, is also still very generally used by the soft wood turners, but to no great extent by any others in England. On the continent it greatly obtains among all classes of turners; an additional back rest, a curved piece of wood like the top portion of a chair back, being there also often hinged beneath the lathe bearers in such a manner that it may be brought out at right angles to them, for support when the workman faces his work in surface turning.
The lathe fig. 21 is taken from an engraving appearing in Plumier's work (1701 - 1749) already referred to; it exhibits the first combination of the spring or archery bow and the wheel in the same machine. These however were employed independently. The bow had a sheave about the center of its string, from which the vertical cord was led around the work to the treadle in the usual manner; the consideration of the wheel will be deferred to the chapter on continuous motion.
The massive wood frame, is in great measure the same as that just referred to, but with some improvement in proportion. The square bars at the top, in like manner, are placed a small distance apart to receive the popit heads; which are fixed beneath by transverse wedges at any distance from each other, according to the length of the work. Both popit heads are provided with center screws, for the twofold purpose of axes for the work and for a finer adjustment for distance.
The reduction from a plate which appears in both editions of the "Manuel du Tourneur," by Bergeron (1792 and 1816) fig. 22, gives a different application of the bow and is without the wheel. The bow is now more rigid, and made of steel, while in place of the one string and sheave as in fig. 21, there are three or four which pass through a sheave or pulley in the center of their length. The cord is wound around the sheave and around the work, the depression of the treadle rotating both; the bow strings being twisted, contract and to a slight extent shorten the stubborn spring, bringing into play the elasticity required to raise the treadle for the succeeding stroke.
The alteration from the pole to the archery bow, was little improvement except that it rendered the reciprocating lathe compact and portable; on the other hand, the advantage of shifting the cord to any part of the work was in great measure lost, and this inconvenience directly led to the adoption of the different methods of producing continuous revolution, described in the succeeding chapter.
Of the lathes with reciprocating motion, those of the simpler construction, fig. 20, and the watch turn or turn bench, alone continue in use; the former, among other purposes, being used for the manufacture of the rods or rounds and legs for chairs, either plain cylindrical pieces tapering towards their ends, or carrying some simple ornament of beads or collars at the center of their length. This industry is sometimes carried on close to the growing wood, the two popit heads with center screws and the turning tools being nearly the only permanent portions of the apparatus; the remainder being constructed of the materials on the spot. The wood for the work having been cut into suitable lengths, is split into pieces to ensure straightness of grain, and these are then chopped and afterwards reduced nearly to size with the paring knife. The pole and the cord are arranged so as to considerably raise the treadle, that the downward stroke of the foot may give the work several revolutions; sufficient to permit the one side of any bead or ornament, to be formed by a single cut of the chisel during one stroke of the foot. Although the body is supported by the back stay, the work is fatiguing on account of the great elevation of the leg necessary for every stroke. The workman therefore obtains relief, by constantly varying his occupation, splitting, chopping and paring one or two dozen rounds, and turning them alternately.
Another instance of the continued use of the pole lathe, is exhibited by the common wooden bowls used for domestic purposes; many of these, are perhaps the largest soft wood hemispheres produced in the lathe, while their manufacture presents some points of interest. The bowls range from four to about eighteen inches in diameter and are externally and internally a fair approximation to the hemisphere; the outside base, slightly flattened that they may stand. They are usually c 2 made from elm, always the plank way of the grain, and are cut one from within the other to save material and labour. The portion of the tree selected is round, straight and without branches, and, as with the portions of the chairs referred to, is manufactured shortly after being felled while still soft and full of sap. The wood is first sawn down the center, which gives it a transverse section approaching the shape of the bowl, it is then cut across into suitable lengths, which are roughly rounded with the axe to a similar section, in the direction of their length. The rough piece fig. 24, is next mounted between the center points of the pole lathe, and the outside turned to shape, leaving a cylindrical portion for the cord. The hand rest is then placed parallel with the surface, and a series of grooves from one to two inches deep, are turned in the face of the work with a strong hook tool, held horizontally; the grooves sufficiently distant from each other to leave the edges of the bowls of appropriate thickness, figs. 25 and 26.