From Hero to Zero

The Rise and Fall of the Slide Rule as the Calculating Tool of Choice

Authored by: Peter M. Hopp

The Routledge Companion to Media Technology and Obsolescence

Print publication date:  December  2018
Online publication date:  November  2018

Print ISBN: 9781138216266
eBook ISBN: 9781315442686
Adobe ISBN:


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The slide rule, the tool for all mathematical occasions. So it was for some 300 years. Those of us who used one for real at school, college, and at work in pre-calculator days, be it as engineer or academic, automatically reached for one when calculation of any sort requiring multiplication and division and more complex maths such as trigonometrical and exponential functions, was required. Most of us owned at least two slide rules, one 5-inch pocket device and a 10-inch desk model—though our transatlantic cousins were rumored to carry a 10-inch one in a scabbard hooked to their belts! Nothing as “flash” for us stiff-upper-lipped British. We had one in our brief cases. I cannot say I mourned my slide rules’ passing when I bought my first calculator, a Sinclair Cambridge in kit form, in the early 1970s. That calculator, despite its idiosyncratic implementation, really was much quicker and more accurate. But was that extra accuracy really necessary? We had certainly got used to “good enough” answers with numbers of significant figures on our trusty slide rules. In any event, the slide rule’s demise was not quite as quick as it could have been—I well remember my boss who had given me some horrible mathematical task to do being amazed when I completed the task well ahead of schedule. “How the blazes have you done that?” he asked. I proudly took out my shiny new Sinclair calculator and showed him. “Great heavens!” said he. “Go away and do it properly with a slide rule.” Over the next few years the electronic pocket calculator became much more common and financially available and the slide rule was gradually relegated to a desk drawer. Like all new technology we had to learn the foibles of calculators. I can remember an inordinate amount of time being spent at work on an “invention” that was to revolutionize our workplace and make all of our fortunes. This turned into a chimera based on an apparent improvement in performance created by the fact that one divided by three and then multiplied by three again gave an answer 0.9999 on most early calculators! It was only after realizing that the next engineering generation was not as mathematically adept as we were that the loss of the slide rule and its attendant numerical methods became something to be valued. There was further evidence of this when recently a maths teacher relation confessed that she had no idea what a slide rule was or indeed what were log-tables. And what was more to the point, they did not teach such things anymore! Realization of the almost complete disappearance of a legendary and ubiquitous tool is now complete.

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