41–50 of 131 posts
I used it a few times, it works, of course, ... but it's not fast and not precise so I don't think anybody would use it to be productive in 2026
It sits in a box
I did a little nostalgia threat on Mastodon recently. The sixth picture is of the slide rule I took to High School in 1973. https://social.bau-ha.us/@raganwald/115979168665997624 Although slide rules are a "dead skill," Aviators typically learn to use something called an E6B Flight Computer, which works on the same principle as a round slide rule. https://pilotinstitute.com/e6b-made-easy/ I have one in my flight bag…
Some of it is pure nostalgia, though, I’ll admit. It a way to honor how people solved similar problems in the past. In the 18th century a sextant plus accurate chronometer or lunar distance table was one of the pivotal technologies of the age; you could use it to pinpoint your location on the boundless ocean within a few miles. That demands respect, and it’s also just really cool it was possible in an era before electricity and radio.
I have no use for them on a day-to-day basis, though. An abacus is more useful for things like counting board game points and adding up taxes.
It can reliably get me 2 sig figs, and a decent guess at a third. But… if I think about it for a minute, I can usually get that in my head anyway. Being able to setup a ratio is great though for unit conversions and things.
It’s also really good for answering that question when driving where you’re like, ok if I go 10mph faster how much sooner will I get there which is otherwise hard to do mentally.
Most of the benefit of using a slide rule in my experience comes not from using it, but from thinking LIKE you’re going to use a slide rule. You learn to freely use scientific notation with ease, and mental estimation to get the order of magnitude right.
And just my 2 cents, but circular slide rules are where it’s at.
I do not use, and have never used, a slide rule. My grandfather was an aeronautical engineering / materials scientist for McDonnell Aircraft, and did a lot of foundational work on heat shields for early space flight (or so I am told). He was eventually named a McDonnell Douglas Fellow, back when there were fewer than 15 Fellows - the company, at the time, took out a full-page ad in Aerospace Magazine announcing it. I…
A key idea is that addition for logs is equivalent to multiplication. To multiply two numbers you line them up on a log scale and then read out the sum, which is equivalent to the product. There is much more they can do but that was one aha moment when my dad showed me his.
My fascination stems from a belief: that slide rule usage helps users develop a certain intuition for numbers whereas the calculator doesn't. To illustrate, suppose someone tries to multiply 123 and 987 with a calculator but incorrectly punches in 123 and 187. My hypothesis is they'll look at the result but won't suspect any problem. The equivalent operation on a slide rule requires fewer physical actions and hence, is less error prone.
Do you think there's anything to this hypothesis?
I did a little nostalgia threat on Mastodon recently. The sixth picture is of the slide rule I took to High School in 1973. https://social.bau-ha.us/@raganwald/115979168665997624 Although slide rules are a "dead skill," Aviators typically learn to use something called an E6B Flight Computer, which works on the same principle as a round slide rule. https://pilotinstitute.com/e6b-made-easy/ I have one in my flight bag…
Similar point applies to being able to use a sextant for celestial navigation in bluewater sailing. GPS is great, until you lose power or your equipment malfunctions. Of course, you can have double or triple redundancy to make such cases vanishingly rare, but still — it’s nice to have a backup that relies on nothing outside your control. Some of it is pure nostalgia, though, I’ll admit. It a way to honor how people s…