This object is part of a collection relating to the history and development of calculating devices assembled by Assoc Professor Allan Bromley of Sydney University, comprising mathematical instruments, slide-rules, mechanical and electronic calculators, electronic analogue computers, computer components, kit computers, education computers, and associated ephemera.

Allan Bromley was a lecturer and researcher at the University of Sydney Basser Department of Computer Science from 1978 until his untimely death in August 2002. He specialised in Computer Architecture, Computer Logic and in particular the History of Computing. He was regarded as the world authority on Charles Babbage's Calculating Engines (instigating the building of the Difference Engine No.2 at the Science Museum London) and the Antikythera Mechanism and had extensive knowledge of calculators, analogue computers, logic, stereopsis, totalisators, clocks and time keeping and mechanical engineering.

Cylindrical pocket slide rule with packaging, Otis King Model K, metal / paper / metal / cardboard, made by Carbic Limited, London, England, 1950s

The Otis King pocket cylindrical calculator is an extendable tube having two slide rule scales, one that is fixed and an extendable one that can be rotated against the fixed one for calculations. The cursor is a brass or blacked metal outer tube that rotates against the two scale tubes. The scales are graduated spiral scales of log-log divisions. The length of the spiral improves the accuracy of the calculation over the standard linear slide rule. Scales on this model are: fixed: no.414, extended: no.423.

Made: 1950 - 1959

Model "K", S/N: U8454

2010/1/84

1950 - 1959