The adoption of the wheel and constant revolution in the lathe, eventually superseded the various methods of obtaining reciprocal motion from poles and springs. But, it is rather curious that the advantages attending this improvement, long previously enjoyed by the potter with his horizontal wheel, should have been so tardily appreciated by the turner; who appears for a long time, still to have adhered to the old and accustomed reciprocating action.

The details of the potter's lathe or "throw," the earliest lathe with continuous revolution were, and still remain, of the most simple character. The workman is always seated in front of a framework which supports a vertical spindle, upon which towards the base, there is a horizontal driving wheel. The spindle was kept in revolution by the action of both feet upon the flat surface of its driving wheel, and the machine is still so used; but is now more generally driven by an assistant with a hand fly wheel, or by power. The work revolves upon a horizontal circular table upon the upper end of the spindle. The term throw, also applied to the clock throw fig. 37, appears to have originated from this art, either from the mass of clay being thrown upon the horizontal surface of the revolving table, which is its sole means of attachment, or from the dimensions of the nascent vessel being extended or thrown outwards by centrifugal force; so great being the latter, that if the speed of the wheel be considerable when the clay is unsupported on the outside by the hand, the plastic material at once spreads out into a flat disc shaped form.

The employment of the feet to give revolution to the potter's wheel, was however not quite invariable. Plate 50 of Rossel-lini's work, previously referred to, represents two ancient Egyptians seated on the ground face to face; the one turning a small wheel without intermission with the left hand, while he fashions the clay placed upon its surface, with his right; the other workman, shaping the outer surface of a vase in a similar manner at another wheel. Other exceptions may doubtless be found, among them are some of the natives of Upper India, who place the clay upon a flat heavy stone supported upon a central pivot; they give the stone a whirl with the hands, quickly fashioning the clay so long as the motion continues, alternately setting the stone in revolution and shaping the work.

In the great majority of machines a vertical position is necessary for the driving wheel; which, in its simplest form is a part of the work itself, turned by a revolving lever or winch handle attached to its axis, as in the grindstone or common draw-well. But when the work requires greater or more uniform velocity, as in the lathe, the driving wheel is detached from the work and mounted upon some part of the machine in connection with the different communicators of the power employed. The earliest representation of the wheel used for driving the lathe, is met with in Schopper's work (1568). He exhibits the detached fly wheel as used by the turner of pewter tankards, who is working at a center lathe set in motion by a fly wheel, turned by a second person. De Caus, "Les raisons des Forces Mouvantes," folio, Paris (1624), plate 8; gives an excellent drawing of a curious lathe for oval turning, also set in motion by a wooden wheel on a detached stand; and Moxon (1677), page 179, thus describes the advantages of the fly wheel.

"Of the Great Wheel."

"Besides the commanding heavy Work about, the Wheel "rids Work faster off than the Pole can do; because the "springing up of the Pole makes an intermission in the "running about of the Work, but with the Wheel the Work "runs always the same way; so that the Tool need never be "off it, unless it be to examine the Work as it is doing."

Felibien (1690), Plumier (1701), and other authors, describe various forms of both hand and foot fly wheels, but nevertheless exhibit a decided preference for the reciprocating motion obtained from the pole or spring bow.

The hand driving wheel fig. 31, is reduced from an engraving in the "Manuel du Tourneur' (1816). The wheel had three speeds and together with its pedestal was constructed entirely of wood; the axis and winch handle were of iron. The cord ran directly on the surface of the work, or, when that was of small diameter, to a pulley fixed upon it. One or two men being employed in turning the wheel according to the magnitude of the work.

Fig. 31.

Center Lathes With Continuous Motion Section I Int 40026