Otis King Model L Pocket Spiral Slide Rule Calculator, England, circa 1935

Description

This cylindrical mathematical slide rule calculator (manufactured by Carbic Limited) consists of 3 tubes.  Two tubes have spiral scales with the smaller one being called the Cylinder which is free to rotate and slide within the large one, referred to as the Holder.  A third tube is mounted on the Holder and forms a tubular Cursor with a pointer at either end.  (Although the pointers are worn on this Otis King, a faint line can still be detected.) Information from Museum of American History provides a description of “A paper spiral logarithmic scale is attached to the top half of the holder. A second  linear and logarithmic, paper scale is attached to the cylinder.  The logarithmic scales are used to multiply and divide, and the linear scale is used to find logarithms.”
When in the closed position, the Otis King measures 6 inches in length and when fully extended, it measures 10 inches in length.  One end is marked Made in England and the other end is marked HO943 (presumably the serial number).   It fits neatly into its original cardboard box with a green paper label marked “Otis King Calculator Model “L” No. H0943”.  This Otis King has been well used and much of the plating has been worn exposing the brass.  Please see all photos for accurate depiction.  For your additional information on using the Otis King, we are including original instructions.
This is an interesting item for the collector of mathematical devices and related measuring and ruling instruments or for your dealers inventory. NO RESERVE!