Ask HN: Is there anyone here who still uses slide rules?

Naw. I used to, but it's so long ago, I'm not sure I could do it now if you put one in front of me. What you don't use atrophies.

Yes. Still use my E6B, no matter how much hate I get from other pilots.

I still use one of mine on occasion. I would say 2-6 times a month.

Yeah, to intimidate kids when they don't deliver academically :)

I have two or three that I inherited from my dad. I've never learned to use them because I haven't thought of something I'd use them for. The one thing I could think of is quickly doing fractional math while woodworking (what width will I have if I rip this 7.5" board into 4 pieces?) but in reality I just don't actually do that much math while woodworking.

Now that's a properly dead skill, surely. I have my dad's one somewhere, and know roughly how it works, but I've not touched it this century.

I also have one of these: https://archive.org/details/spencersdecimalr0000unse ; I believe they were popular around the time of the UK converting to decimal currency, to save people having to do the transitional arithmetic. Had a bunch of other tables in. A physical LUT.

I wonder if there's anyone with abacus skills here. I hear that held out against calculators a lot longer, for shopkeeper uses.

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 have his slide rule, that he used for ages. It's a mystery in a box to me - I have not the foggiest clue how it is used - but I cherish it.

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 and was required to demonstrate proficiency in its use. Of course we fly with connected digital devices these days, but having an analogue backup that operates even if the power fails is important.

Knew a mechanical engineer at a place where I interned. Asked him about it and he joked that he didn't trust those transistors before explaining that it's just muscle memory to him and while a calculator would be faster he'd still earn the same per hour. Apparently I was the first to ask him in over a decade as everyone had moved on to do stuff in software and no one was pushing him to use a calculator anymore. Interns didn't inquire because they thought it must be some esoteric/religious practice. Last I heard he was still working there, management asked him to stay on past retirement age for his invaluable skillset. While its probably some other skill I just like to imagine the suits in a meeting where they decided to keep him on for this particular "skill" that no one else in the company had anymore.

Besides Cliff Stoll? ;-)

Not in a few years, but now that you've reminded me, I should pick the habit back up.

Seen yesterday on someone's blog

[You Need A Kitchen Slide Rule](https://entropicthoughts.com/kitchen-slide-rule)

When I was in high school, (early 1990s,) there was a giant one mounted above the blackboard. It was clearly used for instruction in the past, but it looked so cool that no one wanted to remove it.

Every once in awhile a teacher would spend about 10-15 minutes showing how to use it. Everyone would "oooh" and "awww" and then we would all laugh about how we didn't need to use them now that we all had calculators in our pocket that were more powerful than the computers that put people on the moon.

It's always nice to learn about the past so we can appreciate what we have now.

Yep. I have one and I keep showing off how to do math using it, to kids.I have also replaced the broken slider with a plastic piece after etching the log scale onto it.

You mean like this one:

https://www.flickr.com/photos/jonsphotos/218609214/

My father is an electrical engineer and uses one

I used them in high school in the late 1990s... just to get an extra challenge. I had my dad's and grandfather's and I picked up a couple at garage sales. I still have a collection, but haven't really used them in years. I'll probably break them out again when my kids get in middle school / high school math for fun. They are great for learning the rules of logs.

A big 6-foot K&E sliderule hung at the front of my high-school chemistry classroom, but was never used. At graduation ('91) I asked the teacher if I could have the slide rule and she said "sure".

I keep it now in my office, and once a year I bring to the data visualization class I teach at UChicago, to show how it works, and to show it as an example of a visual device in aid of computational thinking (nomographs being another great example).

Related (60 comments, How slide rules work)

https://news.ycombinator.com/item?id=45985196

I bought a vintage (pre-WW1) circular slide rule. But it's too much of an "artifact" to use - I'm afraid I'd damage it.

We learned to use them in high school (in Canada) in the mid-late '70s. Electronic calculators were just becoming widespread, and not everyone had them.

I think I can do basic calculations with them, although I really haven't touched one in many years.

Yeah. Pickett N600-ES. Sometimes I will solve a problem with it just because I can. Keeps the mental model fresh. Mostly just use an HP 42s though.

I will note I didn't get it or use it until about 1998.

I have a little collection of slide rules. I love those things.

I'm not old enough to have used them to do calculations, but I find them extremely useful to explain logarithms and how multiplication can be represented by the sum of logarithms. I actually work with grad students who should know these things, but watching it in a slide rule on their hands really helps to build intuition.

I own my grandfather's slide rule, he was a master toolmaker for Rolls Royce (aerospace engines) in North London during WW2.