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And in general the site is pretty nice for a museum online. Sure the hpmuseum and the oldcalculators museums are well done but over there they did even more. Of course I didn't check the discussion forum on that site. The new forum here is pretty unbeatable.
Perusing the slide rule museum my eye caught the title of a book " The Slide Rule and Its Use in Problem Solving" that is available as pdf.

I am impressed. Maybe I set the expectation too low for the slide rule and related documentation. Nonetheless the book is barely mentioned in google scholar (that is neat to keep a library of interesting books/articles) or goodreads (that is neat to keep track of books. I should open a thread asking for goodreads lists or the like).

Giving it a quick sample read I observe that:
- the book describes quite some uses of slide rules. Those tools were quite well done! Impressive. I knew that they used logarithms to speed up multiplication and divisions, but then they did scales for a lot more, even complex numbers or triangles. Although the book doesn't always explain why some scales or procedures work (the math behind them). Sometimes it is not that immediate to see what is the math relation behind some choices, like inverted scales that can be used for multiplication too.
- the part of problem solving is also surprisingly "fresh". I was expecting something more dogmatic or "it is this way"
- I go a better grasp why (a cheap) scientific calculator is a slide rule killer - although for some operations the slide rule would be still faster, like conversion.

Every time I see discussion about "I want more digits of accuracy" I roll my eyes, as it is unlikely that one will really need more than 3-4 decimals points (I can understand for purpose of testing or learning though). Anyway this is not true in case of large numbers. Building sections of 5435 meters each (dunno, highway or cables) is something different than 5430 meter. A section 5 meters short can ruin a costly project. Now with the slide rule, at least the standard ones, one mostly could do estimates if large numbers were involved. I wonder if then they did a second pass to compute the numbers down to the required accuracy.
A calculator, even if offering few functions, would surely be awesome in those cases (operations with large numbers) as the accuracy to 5/6 digits could be crucial.
Another point is that one had to be focused on the operations to keep track of intermediate results and to estimate correctly where to place the decimal point.

So my guess at the moment is that when prototyping or developing ideas a slide rule was enough, then something like mechanical calculators had to be used. Or maybe larger slide rules? A calculator offered the chance to avoid the second step.
I've recently fallen in love with slide rules! This is strange, because I've never used a slide rule at school, but I am fascinated by these beautiful instruments.
I already own nine slide rules, linear or circular…

Currently I'm learning the use of slide rules with "The Slide Rule" from Lee H. Johnson. This book gets excellent reviews on the following sites:
Its contains a lot of illustrations based on a real slide rule, and simple diagrams to explain the math behind calculations. Of course it is available on the International Slide Rule Museum.

I've also the book "Slide Rules, a journey through three centuries" from Dieter von Jezierski. It has a nice section on the history of slide rules, plus short articles on the major makers, with comments on some on their remarkable products.

My next book will be "La Règle à Calcul, la longue histoire d'un instrument oublié", from Marc Thomas. It's entirely devoted to the history of slide rules, and their role in the industrial development of our societies. Since this book is in French, there is a strong emphasis on French makers. This book should be available very soon.

Besides the ISRM site, it's worth exploring the site of the Oughtred Society: http://www.oughtred.org

About the number of digits necessary, it depends on the subject. On many physical problems, 3 digits are enough. On the other hand, for ray tracing in optics for example, a lot of digits are necessary, and the advent of computers was a huge progress in optical design.
For calculations with many digits, I think that before calculators, tables were used:
(05-28-2018 12:20 AM)Helix Wrote: [ -> ]I've recently fallen in love with slide rules! This is strange...

You have the ideal username! I have a Helix Standard U12...
I find this channel pretty neat (it is the source that let me discover the slide rule museum)

Actually we should so something equivalent for calculators.
(05-27-2018 09:09 PM)pier4r Wrote: [ -> ]Although the book doesn't always explain why some scales or procedures work (the math behind them). Sometimes it is not that immediate to see what is the math relation behind some choices, like inverted scales that can be used for multiplication too.

I used a slide rule (Pickett N4-ES) through both my undergraduate and graduate college career. I continued to use it at the beginning of my professional career until "sliderule" calculators came out.

I have continued collecting and using slide rules as a hobby. (Second only to HP calculator collecting and using.)

I thought you might be interested in the math that is used to create the various slide rule scales. Thus the attachment. Different manufacturers sometimes used different formulas. For example, the folded scales were not always folded at pi.

Anyway, enjoy.

If you're interested in why some of the slide rule scales work as they do, the manual for the K+E Decilon (available for free at the ISRM) has an entire chapter devoted to this subject. I think this manual is one of the best model-specific slide rule manuals ever printed.

Also, some slide rules are "self-documenting" in that they contain, in addition to the typical scale labels such as A, B, C, D, K, etc., the mathematical formula for the scales. For example, if C and D are x, then the square scales A/B are x^2 and cube scale K is x^3. The Faber Castell 2/83N (picture available at the ISRM) is a good example of this.
Great tip, thanks Benjer.
I went to a calculator only when I needed programmability, in the end of 1981. I still reach for a slide rule sometimes, partly to keep my mind sharp. My slide rules are shown at http://wilsonminesco.com/SlideRules/SlideRules.html .
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