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KF5JRV > TECH 19.08.16 12:28l 79 Lines 4275 Bytes #999 (0) @ WW
BID : 509_KF5JRV
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Subj: Pocket calculating devices
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Sent: 160819/1115Z 509@KF5JRV.#NWAR.AR.USA.NA BPQK1.4.65
Pocket calculating devices
In the early twentieth century, mechanical calculators became common devices
used in commerce and industry. But they remained large and costly machines,
difficult to transport and unsuitable for domestic use. The next step for the
design of calculators was miniaturisation, achieved through precision
engineering and creative recycling of older ideas. With this reduction in size
came a wealth of new designs aimed at broader markets.
Slide rules with style
Otis King's Pocket Calculator is a cylindrical slide rule that was sold by
Carbic Ltd. in London from the 1920s. This 'model K' device was intended to
assist businessmen with multiplication and division. it's style and
simplicity helping to make it a popular device.
Other models of the Otis King Pocket Calculator were designed to perform
specific tasks. The 'model E' would have been a help to shopkeepers, as its
scale converted between money (in units of pounds, shillings and pence) and
weight (in units of ounces and pounds). By writing the scales on a cylinder,
all models of Otis King were small enough to carry in a pocket or purse.
'Not a toy'?
Some of the earliest and most popular 'adding machines' had only a few moving
parts, and were operated by using a pencil or stylus to slide along rows of
numbers. American inventor George Fowler created one such device in 1863.
Fowler's Adding Machine cost $5 when it was launched, which made it a
non-trivial investment.
These stylus devices were cheap to manufacture and became quite popular in the
20th century. Companies such as Wolverine and, later, Hasbro made toys that
were based on the same idea, essentially the same in operation but with fewer
'places', prompting at least one company to retaliate and market their device
as "practical - not a toy."
Stylus adding machines like the Addiator, made in Berlin from the 1920s, and
the Chadwick Magic Brain, made in Japan in the 1950s (Image 2), had a bar that
would clear the previous results. Addiator models varied, sometimes having
different 'screens' for addition and subtraction, along with currency
conversion columns, while the Magic Brain was praised for its simplicity. Even
into the 1970s these devices were marketed as a cheaper alternative to
electronic calculators that 'performed' the same four functions, though
multiplication and division required some thinking.
Whilst most of these early 'pocket calculators' involved a few simple sliding
parts, the next major advance was miniaturisation of the more complex
mechanical calculators.
Curt Herzstark was an Austrian detained by the Nazis in the Buchenwald
concentration camp during World War II. He had been preoccupied with the
design of a better calculator for years, having decided to prioritise the
user interface: he wanted a device that could be held in one hand and quickly
manipulated by the other without a bulky keyboard.
Herzstark revived Leibniz's invention of the single rotating stepped drum,
filing his first patent in 1938, and he continued to work on the details of
his design whilst imprisoned. His captors encouraged him to work on the
device, with the aim of presenting it to Hitler to earn personal glory.
After American troops liberated Buchenwald in 1945, Hertzstark finalised his
design and moved to Liechtenstein to manufacture the device, called the
Curta calculator (Image 3). The country had little infrastructure to support
its manufacture, but the Prince, Franz Joseph II, was so taken with the device
that it became the impetus for starting a crown-supported company, Contina.
Because of its complexity - it was composed of over 600 parts - only around
150,000 were ever made. They were widely regarded as the very best portable
calculators money could buy until the 1970s, when they were superseded by
pocket electronic calculators. One example in the Whipple's collection, a
Type I model, was owned by the Cambridge geologist Brian Harland (1917-2003)
and used by him during his field trips to the island of Svalbard, Norway.
Curtas are now considered a collector's item, and various websites and groups
are devoted to documenting and discussing existing calculators.
73, Scott kf5jrv
KF5JRV @ KF5JRV.#NWAR.AR.USA.NA
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