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.

Calculator with case and instructions, addiator type, Correntator, metal / leather, made by Continentale Buroreform (CBR), Berlin, Germany, 1920-1930

Correntator adder, Addiator style calculator in leather note-book fold case with instructions.
Missing stylus. There is a flap of metal hinged from the centre that swaps the function from addition to subtraction.

Bromley notes:
'Correntator' Stylus Operated Adding Machine
Source: Permondsey Market, London. 1981 / 3 / 13

Large pocket size stylus operated adding machine. Metal construction with flap to change to subtractive markings. Capacity L999,999/19/11 ¾ . In card case.

Good working order. Some surface damage. Missing stylus. Claimed by dealer that he bought this when about 8 years old, and lost the stylus the same day. He remembers the stylus as having a hooked form, and incorporating a propelling pencil in the other end.

Made: 1920 - 1930

2010/1/58

1920 - 1930

140 mm

170 mm

18 mm