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KF5JRV > TECH 26.11.16 15:26l 56 Lines 2721 Bytes #-3214 (0) @ WW
BID : 6016_KF5JRV
Read: DK3UZ GUEST DF7EAV DG4IAK OE7FMI
Subj: Different Slide Rules
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Sent: 161126/1315Z 6016@KF5JRV.#NWAR.AR.USA.NA BPQK6.0.13
Slide rules for other applications
With the rise of the slide rule as an essential aid to calculation, a number
of inventors began to create rules for specialist applications. With no
international standards for their manufacture until the late 19th century,
slide rules could be highly idiosyncratic. Rules made for specific purposes
could have the support of professional groups, and instrument makers vied for
their support by catering to specific needs.
Brewing
Brewing was important for the development of standardisation in industry as
the process had to be monitored carefully and the final proof reported for
taxation and the fixing of price. As is still done today, a hydrometer was
used to measure the changing 'gravity' of the 'wort', which would start off
high due to the presence of fermentable sugars and drop as fermentation
continued.
A brewer's slide rule was used to convert these gravity measurements to others
measurements, for example degrees Plato or proof, which specified the
percentage of alcohol by volume. These scales were not linearly related, and
the slide rule made it easier for the busy brewer to monitor progress.
Improper calibration at any point could lead to customers getting more
(or less) than they bargained for out of a pint!
Finance
The rise of modern commerce relied upon tables that showed changing commodity
prices and compound currency exchanges. Any good capitalist would have his
ready reckoner on hand when transacting a deal.
Slide rules were developed to perform financial calculations, such as working
out interest, more handily. Rather than flipping through a book, a Victorian
banker could align desired conversions using McFarlane's Calculating Cylinder,
a cylindrical rule. While not a logarithmic slide rule, it made use of
rotating scales like in Oughtred's XR Circles of Proportion, and inspired the
design of further cylindrical rules, including ones that could fit into a
shirt pocket.
Military
Galileo's sector had been developed for use as an artillery instrument. With
this in mind, it only makes sense that many slide rules were engineered for
the purpose of calculating firing ranges.
However, slide rules could also serve other purposes on the battlefield. The
Antenna slide rule produced by Lawrence Engineering Service, an American
company that mass-produced millions of slide rules in the mid-20th century.
It was commissioned by the Massachusetts Institute of Technology's Radiation
Laboratory, and was used for calculating radar antenna beam patterns. This
slide rule was considered so strategically important that it's use was
classified until after World War II.
73 Scott KF5JRV
KF5JRV.#NWAR.AR.USA.NA
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