Abacus Tables and Slide Rules
A selection of early calculating aids.
The abacus has two upper rows 'Heaven', whose beads are worth 5 each and five lower rows 'Earth', whose beads have a unit value.
The blue book, (centre rear) is a set of four figure logarithm and trigonometric tables and the opened book (centre right), a set of seven figure tables.
Also shown are two standard slide rules and an Otis King cylindrical slide rule, more accurate than the standard types.
The red book (rear left) is something of an oddity, it is entitled CALCULATING SCALE a substitute for the slide rule and was published in 1903. It contains the equivalent of a 100 inch log scale printed in twenty 5 inch strips and it is to be used with a pair of dividers. It claims to be easier to use than the slide rule, and is interesting because it effectively reverts to the the method of Edmund Gunter who first invented a type of slide rule in 1624.
A personal note:The seven figure tables belonged to my grandfather, the yellowish slide rule belonged to my father and the other slide rule I used at school. The set of four figure tables is inscribed "...to be left on the candidate's desk at the end of the examination", but it wasn't.
Hand cranked mechanical calculators come in two main types, those that use the Leibnitz stepped gear and those that use the so-called "pinwheel". The Leibnitz stepped gear is described in the historical section. The stepped gear is used in the MADAS and Curta calculators in this collection.
The pinwheel is a much later development and was invented in the late 1870s independently by Frank Stephen Baldwin in the United states (1875) and by Willgodt Theophil Odhner (1878). Odhner was Swedish, although he was living and working in Russia at the time of his invention.
Baldwin's devices were eventually manufactured in America by the Monroe Calculating Machine Company. Odhner started manufacture of his machines in Russia in the late 1880s, but in 1917, the year of the Russian revolution, he moved his business to Sweden. A descendent of this original company manufactured the Facit series of calculators.
Odhner sold the German manufacturing rights of his calculator to a company based in Braunschweig. This company sold their calculators under the name Brunsviga.
TELL ME More about pinwheel calculators - how did they work?
Inventory No: 0006
Serial No: 214207
The classic pin wheel machine, based on the original Odhner patent. It is inscribed:-
Brunsviga Maschinewerke AtG Braunschweig.
Brunsviga 18 opened
The Brunsviga 18, with part of its casing removed to show the pinwheel cylinder. A diagonal array of carry pins is visible running from lower left to upper right of the cylinder. These have just completed the carry sequence.
NOTE: The Brunsviga cylinder is directly driven by the crank handle and an addition would cause the cylinder to revolve so that the pins in the illustration move upwards. Confusingly, with the Marchant calculator, the opposite is true because its cylinder driven off the crank by a pair of gears and its direction of rotation is accordingly reversed.
Inventory No: 0007
Serial No: 174946
In 1959, Brunsviga merged with the Olympia company and this calculator dates from that association
It is inscribed:-
Olympia Werke AG Wilhelmshaven - Made in Spain.
Inventory No: 0189
Serial No: 12-31993
This machine dates from after the merger with the Olympia company.
It is inscribed:-
BRUNSVIGA Olympia Business Machines Co. Ltd. London W.C.1. Made in Western Germany.
Inventory No: 0003
Serial No: XL92307
This calculator is the oldest in the collection and dates from the mid 1920s.
Marchant XL opened.
The illustration shows the cylinder with the line of transfer gears and carry cams lying between the cylinder and the array of figure wheels of the output register (18 figures!). To the right of the machine are the 9 wheels of the second register, used for multiplication and division
TELL ME More about Marchant Calculator - how to multiply and divide
Inventory No: 0165
A pinwheel type mechanical calculator from Busicom, the firm that indirectly started the micro-computer revolution. Their association with Intel led to the development of the 4004 series of chips - the first microprocessor.
TELL ME More about Busicom and Intel