The iPhone of slide rules

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So it’s expensive, locked down, and made out of marketing hype?


I think I’m the very last generation to actually learn how to use a slide rule - and it was obsolete even then. It does have a few benefits, like forcing you to think about the reasonableness of your answer, and how many significant figures to use, rather than, “all of them.”


My stepfather’s K&E slide rule turned up at a holiday party. We all just had to figure out (oops, I mean remember) how it worked. Something about logarithms and sliding scales. Turns out that it was actually quite accurate, too. At least three digits, maybe four.

One of my friends has one of these hanging in his living room, for just in case the power goes out.



I used a slide rule in college (Pickett N3 - still in my desk at home). And it shows when I do a financial presentation. “Projected revenue is approximately $11,200,000” where my spreadsheet-educated colleagues will say “Projected revenue is approximately $11,187,223”.


I have a Picket N1010-ES Trig right here. Still have its leather case, tho I don’t wear it.


I can’t find my old one (still somewhere in the boxes we haven’t unpacked) but it’s funny how things go.

45 years ago this past September, I was taking physics classes and it was a hot topic whether to allow slide rules on exams. This past September, I’m back to taking physics classes and calculators are back to being a hot topic because too many are networked and capable of looking up solutions – but slide rules are as controversial as wooden pencils.

And one of my professors actually gives extra credit for using a slide rule. Gotta track down another for at least until I find my old one.


I’ll see your N1010-ES…

One like this carried me all through university. (Picture is not mine. It’s from Eric’s Slide Rule Site, an excellent source for anyone interested.) In the sense of doing things differently from most other manufacturers, one could argue for Pickett being the Apple of slide rules.

In the video, Bellos uses the A and B scales to multiply and divide. This is not standard practice (i.e. it’s totally wrong), and I’ve never seen anyone do it. The C and D scales are the ones to use, because they can be read more accurately.


We were allowed to use slide rules in chemistry exams - they’re cheap (basic plastic ones were probably $10 or less), so they were universally available, every chemist needed to know how to use one to do real work, and you still had to do the thinking yourself (including knowing what power of 10 went with the digits you got), and while they weren’t perfectly accurate, neither was your real-world data. It was a couple years after your physics class, so calculators were starting to appear, but weren’t cheap enough to be universal.

I didn’t have to do cube roots very often, but you could do that with the basic 9-scale models by turning the slide upside down. I think I was mostly using a 13-scale.


I still use one (slide rule, not an iphone or calculex), and bought one for my son a few years ago as a HS graduation present.

Ah, Circular slide rules.
You didn’t go “off-scale” with them as it was a continuous log line, not a line with beginning and end.

Still made cheaply by Concise. See the Circular Slide Rule No. 300 version for a standard “10 inch” model at:

And the very large, world´s biggest computer museum Heinz Nixdorf computing museum in Paderborn, Germany.

And many, many more at
Hundreds more enthusiast collections at

Very old circulars

The Oughtred Society Combined Winter and Summer Meeting will be held in Las Vegas at the Atomic Testing Museum on May 7, 2016.
The Oughtred Society was founded in 1991 by a group of slide rule collectors and is dedicated to the preservation and history of slide rules and other calculating instruments. In the past 24 years it has evolved to an international organization with members in 22 countries

In high school (class of 63) I not only wore a slide rule in a holster on my belt, but fastened the bottom to my thigh with a leather thong to facilitate a quick draw. Fortunately I was 6’2", 220 pounds, all-state defensive guard, and student body president.

I’d give it all up for that 10-foot K&E log-log-duplex-decitrig shown in an earlier comment by nixiebunny.

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Here is a virtual 909 ES you can project onto your wall from your PC
3-D as well
Yet Another Sliderule Simulation

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You might be interested in

“Pocket-Watch Slide Rules”
from Astragal Press

This book is about one of the most attractive and tactile forms of slide rules, the pocket-watch slide rule. Although pocket-watch slide rules were not the most accurate nor easy to use, these delightful devices were in makers catalogues from all parts of the world for the last century of the slide rule’s life. Pocket-watch slide rules are an exquisite example of the slide rule makers’ art and are perhaps the most collectable type of slide rules.

The Book Includes:
-Detailed descriptions of over 150 pocket-watch slide rules and variants
-Hundreds of full-color illustrations, detailed descriptions, and dating information
-Approximately 80 makers and retailers from the UK, Europe, and the USA
-Descriptions of special scales used
-Coverage of seminal patents
-A glossary of terms
-A comprehensive bibliography

184 pages, Paperback, Full Color, 8.5" x 11", © 2011
Order Number: AP6316…$39.95

From the back cover: Peter Hopp needs no introduction to slide rule collectors throughout the world. His first book Slide Rules – their History, Models and Makers, published in 1999, has become the point of first reference for all slide rule collectors.
This work was followed by a detailed study of joint slide rules in his book Joint Slide Rules – Sectors, 2-foot 2-fold and slide rules, published in 2009.
Drawing on his years of slide rule collecting experience we now have Hopp’s latest extensively researched book Pocket-Watch Slide Rules. Starting with an analysis of the various types of pocket-watch slide rules, an historic review of the oldest types and patents, the book continues with a review of worldwide manufacture.
A comprehensive survey of pocket-watch slide rules is given by ‘family’ sub-divided with relevant information including some unidentified examples and examples known to exist but as yet undiscovered. The latter part of the book deals with non-mathematical types of pocket-watch calculators and wrist-watch slide rules.
Finally the book contains a list of known worldwide manufacturers and retailers and an appendix with operating instructions and hints on identifying makers of unmarked versions.
In its non-technical style and logical layout, both the casual collector and the connoisseur will find information and delight in this book covering, as it does, aspects of design and construction from the earliest known examples to the demise of the slide rule in general use.

I don’t think you need a slide rule to not be that silly.

Also: wow.

How many pence?

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