It wasn’t all that long ago that engineers, astronauts, mathematicians, and students proudly carried the original pocket calculator. I had one and thought I was proficient at it. Sadly, I misplaced it years ago.
The slide rule was a simple device with one sliding part that could do complex mathematical calculations in moments. Multiplication, division, roots, logarithms, and even trigonometry could be performed with ease. But as technology marched forward with sophisticated computers and graphing pocket calculators, the lowly slide rule was forgotten.
Much of the engineering of the world we live in was designed with the use of slide rules, and yet they are almost forgotten today. Do you have a teen-aged child or grandchild? If so, ask him or her what a slide rule is. I suspect he or she won’t know.
Wikipedia states that William Oughtred and others developed the slide rule in the 17th century, based on the emerging work on logarithms by John Napier. The online encyclopedia then goes on at length to describe the history, use of, and eventual obsolescence of the slide rule. You can read the article at http://en.wikipedia.org/wiki/Slide_rule.
Want to amaze your grandchildren? Buy a slide rule to show them. You can also keep it for nostalgia reasons. Slide rules can still be purchased from a number of vendors for about $20 or so if you start at https://bit.ly/3AHPZRb.
No batteries required.