Brass, the short bevelled pinion section engraved 6 to 18, with one long wheel section arm signed T Jump and the other engraved 20 to 100 and divided into ten, with 1/8, 1/4, 1/2, 1 and 2 inch engraving on the locking slide. 13 inches (33.5 cm) in length.
Thomas Jump, working in Prescot, is thought to have been the first to adapt this form of proportional gauge for use in clockmaking. See the article ‘The Jumps and their Sectors’ by Vaudrey Mercer in Antiquarian Horology, December 1983, pages 406-11. See also Britten’s Handbook… for a full description of its use.
Good unpolished condition, the locking nuts probably replaced.