Page:The Kinematics of Machinery.djvu/234

 212 KINEMATICS OF MACHINERY.

knee-shaped tool-rest in front of it, and begins his work. Consider- ing the simple nature of his machine he makes exceedingly good work.* It may be noted that he turns by preference bowl-shaped pieces of wood, horn, metal, &c. This arises from the construction of his lathe, in which the want of a second support for the piece which is being turned, or what we call a movable headstock, compelled him to choose either flat or hollow pieces for his work. Thus both the construction of the machine and the kind of work produced by it point out its descent from the potter's wheel. We are led to a similar conclusion by the circumstance that among the Eomans 34 the turner was not only called tornator but also vascularius,f that is, dish- or bowl-maker. Whether or not the two expressions were used interchangeably, we know at least that the vascularius used the lathe often, and with great skill, as various vessels and fragments show. Thus this bowl-lathe appears as a connecting link between the potter's wheel and the lathe for turning long bars. In later times the Kalmuck turner has made himself independent of assistance, at least for light work, by taking one end of the driving cord with his left hand, and the other between the toes of the left foot, keeping his right hand still free to handle the chisel,

The skill of the Roman turners displayed itself in many ways ; they could, for example, turn stone bowls with sides of the ex- tremest thinness, they even knew how to turn glass vessels, as appears from fragments of them in the Minutoli collection. Nor were they skilled only in the more delicate kind of turnery ; for we find that they could and did also turn immense stone columns or drums in the lathe.J

Although we know that the old Egyptians employed the art of turning, we know little as to their modes of working in it. 35 Perhaps we may venture to think that the lathe still used in Egypt, which is shown in the following engraving, is descended directly from that used in Pharaoh's kingdom. The simplicity of this instrument is primitive, a is the piece (of wood) to be turned ; it rests between two iron points at I and c, and can be turned by

t Cic. Verrin. iv. 24.
 * See Bergmann, Nomad. Streifereien u.d. Kalmucken (Riga, 1804) ii. 171.

J See Ottfr. Mailer's Arcliaologie der Kunst, after Klenze, in Bottiger's Amalthcea, ii. p. 72.