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YORK Borg-Warner Item associated with a Discovery 400 Years Ago

Front and Back of YORK Borg-Warner imprinted Pickett Slide Rule (Collection of S. H. Smith)
Front and Back of YORK Borg-Warner imprinted Pickett Slide Rule (Collection of S. H. Smith)

John Napier discovered logarithms 400 years ago. Napier published his theories of logarithms in 1614. The slide rule functions because the primary slides are engraved with distances that are proportional to the logarithms of the engraved numbers.

I started to work as an Engineer at YORK Division of Borg-Warner Corporation in 1972. At that time, a slide rule was the primary method used to perform design calculations. I say primary, because everyone on the second floor of Building 23 also shared one large Wang Desktop Calculator. The Wang was only used for the most complex design calculations; such as raising a number to a fractional power.

I’ve set the pictured slide to solve for the Circumference of an 11.4-inch diameter pipe using the C and D scales. Read the result 35.8-inches under the hairline cursor on the D scale.

A few electronic calculators were on the market in 1972, however they were well out of most peoples price range; i.e. many hundreds of dollars. The calculator that produced the price breakthrough was the Texas Instruments SR-10. The SR-10 came out in 1973; at a significant reduction in cost versus anything previously on the market. The SR-10 cost $149.95; it was still relatively pricy, when one considers $149.95 in 1973 is equivalent to about $850 today.

A TI SR-10 performed seven functions: add, subtract, multiply, divide, squares, square roots and reciprocals. Through a volume discount arranged by the company, nearly every engineer at YORK owned an SR-10. Desktop computers would follow nearly a decade later; at first shared, but eventually on the desk of every engineer.

I’ve ordered the slide rule scales from most used, to least used, in this functional summary:

  • C and D: for Multiplication and Division
  • A and B: for Square and Square Root
  • CI: for Reciprocals
  • L: for Common Logarithms
  • K: for Cube and Cube Root
  • S: for Sines and Cosines
  • T: for Tangents and Cotangents
  • ST: Sines and Tangents for Small Angles (less than 5.7 degrees)

YORK Manufacturing Company was established in 1874 and evolved into YORK Ice Machinery Corporation; then YORK Corporation. It was locally headquartered and independent until becoming the YORK Division of Borg-Warner Corporation in 1956. YORK International Corporation was spun-off by Borg-Warner in 1986 to return to being a locally headquartered, independent corporation; until in 2005, when it became part of Johnson Controls.

During much of YORK’s first 100-Years, from 1874 to 1974, slide rules were the tool used by engineers to do design calculations. Tom Shipley was responsible for the tremendous growth of YORK between 1897 and 1930. Tom also designed many of the early products. It is probably a good bet that Tom Shipley had a slide rule on his desk.

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