Slide Rule: Putting Man on the Moon

Nikhil Augustine
History of Education Timeline
3 min readSep 10, 2019

From Bunsen burner to the Protractor, playing audio records in class ranging from history to music lessons, Drawing arcs and circles with a compass in geometry to seeing complicated graphs being represented with ease in graphing calculators, from programming in basic to Virtual Reality. These tools of education became part of our education for a year or two then we moved on to something greater and fancier. Regardless, there was once a device without which higher level math’s was almost impossible to do in classrooms and workplaces, applicable everywhere from basic trigonometry to complex flight calculations, now has all but disappeared:

The Slide Rule

Before the smartphone, the laptop and the graphing calculator, there was the slide rule. It’s a powerful mechanical computing device, often no larger than a 12-inch ruler, marked with numbers — but part of it slides in an out to show relationships between different sets of numbers. The slide rule is used primarily for multiplication and division, and also for functions such as exponents, roots, logarithms, and trigonometry, but typically not for addition or subtraction. The Irony is although the slide rule is similar in name and appearance with a standard ruler, the slide rule was never meant to be used for measuring length or drawing straight lines. However this seemingly simple tool has a serious resume. NASA engineers used slide rules to build the rockets and plan the whole mission that landed Apollo 11 on the moon. It is also said that Buzz Aldrin needed his pocket slide rule for intense last-minute calculations which were complex and didn’t have room for error to successfully land on the moon.

“The slide rule is an instrument that was used to design virtually everything,” says Deborah Douglas, the director of collections and curator of science and technology at the MIT Museum in Cambridge, Mass.

The slide rule has a long and distinguished ancestry, our last century could not have been built without the slide rule, yet its direct evidence is almost totally missing to the uninformed eye. In a span of three and a half centuries. It was used to perform measurements, design iterations and do calculations for virtually all the major structures built on this earth during that long period of our history. It has an amazing legacy for something so mechanically simple with a long list of achievements.

In Modern times teachers in few universities across the world still teach their students how to use the slide rule to make sure that it’s not forgotten. How simply three pieces of wood or plastic could people reach for the skies something that’s still hard to do with modern computers and advanced tech.

For generations of engineers, technicians and scientists, the slide rule was an essential part of their daily lives. Until, all of a sudden, it wasn’t. In 1972 Hewlett-Packard came out with the first handheld electronic calculator and practically overnight, the slide rule had become obsolete.

Sources:

  1. https://www.npr.org/sections/ed/2014/10/22/356937347/the-slide-rule-a-computing-device-that-put-a-man-on-the-moon
  2. Image: https://www.npr.org/assets/news/2014/10/sliderule101.gif
  3. http://www.oughtred.org/history.shtml
  4. https://en.wikipedia.org/wiki/Slide_rule

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