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Posted by ColinWright 5 hours ago

How Slide Rules Work(amenzwa.github.io)
55 points | 14 comments
throw0101a 58 minutes ago|
This education film from 1957 gives a good overview of using one:

* https://www.youtube.com/watch?v=oYQdKbQ-sgM

"Professor Herning" (?) also has a good series of videos on the use of various scales as well:

* https://www.youtube.com/@ProfessorHerning/videos

His playlist starting at the beginning (C and D scales) with a Manheim layout:

* https://www.youtube.com/playlist?list=PL_qcL_RF-ZyvWJJkJOk_O...

* https://sliderulemuseum.com/Manuals/M37_Post_Manheim_Instruc...

Some manuals / books on slide rules:

* 1909: https://archive.org/details/mannheimsliderul00coxwrich

* 1922: https://archive.org/details/cu31924002978561/mode/2up

JKCalhoun 3 hours ago||
Deep dive, for sure. I suspect Cliff Stoll is enjoying this site.

I played with creating a logarithmic slider thing [1] in Javascript that I hoped I could package up as a kind of "widget" people could use on their web pages. But I don't really know Javascript that well—or rather how to make an API out of a Javascript thing.

Anyway, to test it I tried to make an Ohm's Law calculator [2].

I would love to see a site like the one in this post have some kind of interactive slide rule on the web page itself.

[1] https://github.com/EngineersNeedArt/SlideRule

[2] https://www.engineersneedart.com/ohmslaw/index.html (the yellow slider is not directly user-moveable in this example)

watersb 1 hour ago||
A sort of non-logarithmic slide rule, the E6B Flight Computer, was still in use when I was a student pilot 20 years ago. I still carry one: they don't require electricity (although using one in the dark requires a light source).

https://en.wikipedia.org/wiki/E6B

KK7NIL 1 hour ago|
The main part of the E6B is a very standard logarithmic slide rule. Having it loop unto itself is a neat trick but very ancient.

But perhaps you were referring to one of the many other parts of the E6B which I am not familiar with.

egl2020 1 hour ago||
I still have the wooden 10" Keuffel and Esser that I inherited from my father and that I used in college. These days I use my HP15C unless I want to provoke glee and amusement in my younger colleagues by sporting my Pickett slide rule in my shirt pocket.
jamesgill 1 hour ago||
Last week I donated several slide rules to Goodwill; a few were very nice. Meanwhile, I still have a pristine HP-41cx and HP-15c, and an HP-25 app on my iPhone.
incanus77 1 hour ago|
I have an HP-15c as well as a 16c and I've been using the latter on a daily basis while writing a byte-level network protocol client. I'm getting faster by the day and on the verge of writing some programs for shortcuts on the calculator. I still use the excellent PCalc as well, but seem to be faster on the physical calculator, which is kind of surprising.
clickety_clack 2 hours ago||
Slide rules are super cool. Such an easy gift to give the engineer in your life.

I never spent the time to get quick with it, but I could absolutely see it being quicker than a calculator. You’d just have to be aware of the limits to its precision if you were in a field that required it.

deepspace 1 hour ago|
Quicker than an algebraic calculator, maybe, but very few people could get. faster with a slide rule than an ergonomic RPN calculator. like the HP 41 series. And I say that as an enthusiastic and experienced slide rule user, before I switched to a calculator.

One problem with a slide rule is that it only performs operations on normalized mantissas. You have to keep a parallel exponent calculation in your head, and that slows you down. Also, maintaining best precision slows you down.

fjfaase 2 hours ago||
I have one at home, which is the one we had to buy to use in highschool. In the math classrooms we had a 6 feet version that could be mounted on the blackboard such that the teacher could used for instruction. See for a picture on the Dutch page https://rekenlat.barneveld.com/rekenliniaal.htm
watersb 1 hour ago|
These TMSLs were also reasonably common in classrooms in the United States in the 1950s.

Two Meter Slide Rule

gerdesj 2 hours ago||
It is worth keeping one around.

When the "cloud" is raining and your laptop and phone batteries are drained and you suddenly need to navigate your 4823 times table - its got you covered.

You will also need to work out how to write with a pen or pencil on paper or try and fix up your atrophied ability to remember arbitrary "facts" short term.

NetMageSCW 2 hours ago||
The HP-35 wasn’t programmable- it was just a scientific calculator.
kingforaday 3 hours ago|
This would have been helpful for Sam Cooke.