The practical draughtsman's book of industrial design and machinist's and engineer's companion : forming a complete course of mechanical, engineering and architectural drawing (1866)
Armengaud, M. (Jacques Eugène), 1810-1891, Armengaud, M. (Charles), 1813-1893, Amouroux, M. (Jules), Johnson, William, 1823-1846 · Philadelphia : H.C. Baird · leaf 202
n which it isplaced In ordinary instruments the legs, o and p, ter-minate in simple points, which are respectively causedto traverse the grooves in the guide-plate, Q, in describ-ing the ellipse. It is, however, found to be almostimpossible to obtain a smooth action with this arrangement, asthe… … Fig. 30. an uneven outline. In the instrument represented in figs. 29 and30, the parts which traverse the guide-grooves in the plate, q, con-sist of small steel wheels, o, p, carried in the forked ends of the * See page 17. steel spindles, o, p, which are entered loose into the socket legs,o, p.…
