TRAMMEL

(Old French, tramel.) An instrument for drawing ovals, much in use among -J! joiners and other artificers. It consists of a cro , C D E F, in which are cut two grooves at right angles to each other; and a beam, A B, carrying two pins, G, H (which are clamped to A B, and slide in their grooves), as well as a pencil P: these parts are called the cro and the beam. By turning A B rouna, the pins G, H slide along the grooves, and the pencil P describes an elliptic curve. A demonstration of the properties of this instrument may be seen at p. 700, vol. xiv. of Hutton's Abridgment of the Philosophical Transactions. [s. 1273]