This Mahogany and brass Fuller's spiral slide rule with serial number 4046/18 was made and signed by ‘W.F. Stanley Great Turnstile, London, England’, and consists of 3 hollow cylinders: The middle (axis) cylinder is fixed to the handle and contains useful tables and equations. The inner brass cylinder slides into the axis like a telescope tube and the outer cylinder can move up and down and turned round the axis. A single logarithmic scale 500 inch long (12.7 meter) is wound spirally around the outer cylinder to enable calculations to 4 or 5 place accuracy. The original dovetailed mahogany box and brass-mounting bracket are in very good overall condition. The original instruction manual for the use of the rule (dated 1916) is included. The case is 46 cm. (1ft. 6ins.) wide.