70 Years with a Slide Rule

As I unpacked a box – filled with items that are too good to leave, but haven’t been needed in 5 years, I came across my old slide rule.  My first slide rule – purchased in Japan for my first birthday.  From high school on, I used this rule, until I retired it for a 6” Pickett that went on snow surveys. 

It’s labeled Sun and Hemmi – a 50W . . . all things that mean nothing anymore.  Wikipedia notes “Around 1974 the handheld electronic scientific calculator made slide rules largely obsolete.”  I hung on using a slide rule until 1980 – the first electronic calculators tended to error in sub-zero temperatures, and we needed to perform and check our calculations on site.  The one pictured below had a longer working career – it, like mine, was purchased in Japan in 1950 – but by a sophomore engineering student, who went on to teach electrical engineering. It had a more productive life before the programmable calculators pushed it aside.

The little Pickett – I could replace it if it dropped into the snow and couldn’t be found.

That first electronic calculator was a Texas Instruments Electronic Slide Rule – mine was, I believe, an SR-56 that I bought second-hand (HP had become the standard) that read only in scientific notation.  It got seven or eight years of working service, then moved into a classroom aid for teaching notation.  About 2000, realizing its historical significance, I took the battery out and put the old tool in the box, and left it with the historical village.

Still, I’ve kept my old Hemmi – it’s bamboo construction is self-lubricating, and it is a bit smoother than the metal Pickett rules.  If the power goes out, I can still calculate by daylight.

The slide rule was invented in 1620, by an Anglican minister named William Outred.  It works on logarithms.  For 350 years it reigned supreme among engineers and mathematicians.  

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