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South African's collection includes The Millionaire calculator, Thacher slide rule

By Neal McChristy

The MillionaireThe Millionaire calculator, which was produced from 1895-1935 by Hans W. Egli and invented by Otto Steifer in 1892, is a rarity in South Africa where Gerald Stoch lives.

The resident from Emmarentia, a suburb of Johannesburg, South Africa, (click for map from has one of two known to exist in South Africa. The other one is housed in the SA Railways Transport Museum, Stoch said. "Both these machine were originally used in the land survey office of what was then the SA Railways and Harbours government offices," Stoch said.

"What makes this machine unique is that it is a true multiplication machine as distinct from most other calculating machines which are really successive adders in which you have to get the decimal place correct and then crank the handle the required number of times," Stoch said. "With the Millionaire the one multiplier is 'keyed' in.

"A lever is set to the position of the rightmost number in the second multiplier, the crank is only turned once to complete the multiplication for the first number. The machine automatically advances the decimal position, the lever is set for the next number followed again by a single turn of the main crank and so on until all the numbers in the second multiplier have been processed with a single turn of the crank."

GeraldThe calculator was known as the first calculator to perform multiplication rapidly. The Millionaire was patented in the United States by Egli, of Zurich, Switzerland, according to Stoch. There were about 4,700 units sold, according to A brief history of mechanical calculators by James Redin at

Stoch was a structural engineer until the late '60s, when he said "I decided to do something about getting onto the 'Computer Bus' - afraid I might miss it. That was in the days of IBM1130s, but I wasn't really into mainframe computers. Yes, an IBM 1130 with 8K RAM was considered pretty close to 'mainframe' in those days. So I cut my teeth on an Olivetti Programma 101 with all of (I think) 240 bytes of memory - weighed 75 pounds and (I) lugged it home every night from the office to develop wondrous engineering analysis software."

GardenStoch says he gave up practice in 1972 to establish Metricomp Programmes and converted software to use with the HP 9820, which now stands on the floor in his home office with a sign that reads, "Confucious says, 'Computer without software may as well be doorstop.' " He later became Hewlett-Packard's first South Africa OEM before there was an acronym for OEMs. He started developing stock-exchange software and Metricomp grew to 20-some staff. He also got involved as agent for a computer-aided design system developed in El Paso, Texas. Over the past 10 years, he said Metricomp has slimmed to his wife, Sadie, as chief assistant, and himself, "marketing a specialized engineering program for finite element analysis in which I have become a bit of an expert and now also do a measure of consulting to my colleagues. We now work from our home."

He became interested in collecting calculators 20 years ago. He said he "decided not to get involved with new-fangled electronic stuff - had to be driven by hand or steam!" Thacher slide rule

Stoch's collection also contains another unique item, a cylindrical slide rule invented by Edwin Thacher and patented Nov. 1, 1881. According to Antiques of Science of Technology, a Web site, the calculator "came with a 71-page instruction manual filled to the brim with equations symbols and mathematical tables."

Thacher 2"My invention relates to certain improvements in logarithmic slide-rules, and in general terms, consists in making the rule of cylindrical form," states Thacher's patent application to the U.S. Patent Office,, "having a rotary and longitudinally moving slide inclosed (sic) by a series of bars or an envelope, and on such slide and bars are arranged logarithmic scales of greater length than the length of the graduated space of the rule, parts of such scales being laid off on separate parallel lines . . ."

To send e-mail to Gerald Stoch, Johannesburg, South Africa, click here

If you have antique equipment, we're interested in writing about it. To send e-mail to Neal McChristy, editor of RS&R News, click here, or call at 800/825-9633, ext. 238.

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Related Web sites:
American Artifacts: Thacher's calculating instrument, with photo
History of computers and calculators: "Brass gears and musclepower"
A Brief History of Mechanical Calculators, Part II, "Crossing the 19th Century" by James Redin
The Millionaire calculator, with photo
The multiplication principle of the Millionaire calculator, with photo

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