526,240. Stretching and doubling yarns. TANNER BROS. (GREENFIELD), Ltd., TANNER G., and WINTERBOTTOM, J. Feb. 11, 1939, No. 4568. Class 120 (ii)] In a yam twisting and doubling machine the yarn is stretched by being passed to and fro over grooved cones secured upon or formed integrally with the doubling rollers which are arranged in two parallel lines,and positively driven. As shown the yam from the bobbin b to the spool c, onto which it is wound by a ring and traveller, passes to and fro around the grooved cones d, e on the positively-driven rollers f, g ; the extent of the stretch imparted to the yarn may be varied by varying the number of times the yam passes to and fro around the cones.