I am excerpting this obit from the New York Times of Walter Shawlee, an EE whose passion was slide rules:
For about 350 years, humanity’s most innovative hand-held computer was something called a slide rule. As typewriters once symbolized the writer, slide rules symbolized the engineer.
These analog calculators came in metal, wood, plastic and even bamboo, and they could be found all over the world. Their functions included computing higher-order multiplications, exponents and logarithms, among other mathematical operations. They were usually long and rectangular with a retractable middle segment, and they featured dense fields of letters, lines and numbers stacked on top of one another.
They looked almost comically abstruse, as if they might be used as paddles in the hazing rituals of a math fraternity.
Non-nerds struggled to make sense of them. Then, in the early 1970s, lightweight electronic calculators became widely available. The market for slide rules collapsed, and manufacturing of new devices essentially ceased.
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One of Mr. Shawlee’s prized possessions was a Faber Castell 2/83N slide rule, considered by many to be the Rolls-Royce of the devices.Credit...Sphere Research Corporation
One day, about 20 years later, a middle-aged avionics engineer by the name of Walter Shawlee was looking through a drawer at his home in Kelowna, a midsize city in British Columbia, when he happened upon his old slide rule from high school.
It was a Keuffel & Esser pocket Deci-Lon, model 68-1130, with a slender Ivorite body and delicate see-through cursor box. Both had stood the test of time. Mr. Shawlee remembered that as a teenager he had spent six months saving up money to buy it.
Inspired by this encounter with his youth, he created a website dedicated to slide rules. Before long, nostalgic math whizzes of decades past came across the site. Emails poured into Mr. Shawlee’s inbox. He began spending eight hours a day researching, buying, fixing and reselling old slide rules.
“Are you trying to corner the slide-rule market?” his wife, Susan Shawlee, asked him nervously, The Wall Street Journal reported in 2003.
The magazine of the Institute of Electrical and Electronics Engineers, Spectrum, determined in 2007 that Mr. Shawlee had, in fact, “cornered the world market.”
“He’s Mr. Slide Rule,” a Texas engineer and slide-rule enthusiast told The Journal. “Walter knows everybody in the slide-rule racket.”
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Mr. Shawlee in 2018. “He’s Mr. Slide Rule,” a Texas engineer and slide-rule enthusiast was quoted as saying. “Walter knows everybody in the slide-rule racket.”Credit...Sphere Research Corporation
Mr. Shawlee died on Sept. 4 last year at his home in Kelowna. He was 73. The death was not widely reported at the time, and The New York Times was notified about it only last month. His wife said the cause was cancer.
Walter Shawlee, the Sovereign of Slide Rules, Is Dead at 73
Used by engineers for centuries, they were displaced by pocket calculators and all but forgotten until Mr. Shawlee created a subculture of obsessives and cornered the market.For about 350 years, humanity’s most innovative hand-held computer was something called a slide rule. As typewriters once symbolized the writer, slide rules symbolized the engineer.
These analog calculators came in metal, wood, plastic and even bamboo, and they could be found all over the world. Their functions included computing higher-order multiplications, exponents and logarithms, among other mathematical operations. They were usually long and rectangular with a retractable middle segment, and they featured dense fields of letters, lines and numbers stacked on top of one another.
They looked almost comically abstruse, as if they might be used as paddles in the hazing rituals of a math fraternity.
Non-nerds struggled to make sense of them. Then, in the early 1970s, lightweight electronic calculators became widely available. The market for slide rules collapsed, and manufacturing of new devices essentially ceased.
Image
One of Mr. Shawlee’s prized possessions was a Faber Castell 2/83N slide rule, considered by many to be the Rolls-Royce of the devices.Credit...Sphere Research Corporation
One day, about 20 years later, a middle-aged avionics engineer by the name of Walter Shawlee was looking through a drawer at his home in Kelowna, a midsize city in British Columbia, when he happened upon his old slide rule from high school.
It was a Keuffel & Esser pocket Deci-Lon, model 68-1130, with a slender Ivorite body and delicate see-through cursor box. Both had stood the test of time. Mr. Shawlee remembered that as a teenager he had spent six months saving up money to buy it.
Inspired by this encounter with his youth, he created a website dedicated to slide rules. Before long, nostalgic math whizzes of decades past came across the site. Emails poured into Mr. Shawlee’s inbox. He began spending eight hours a day researching, buying, fixing and reselling old slide rules.
“Are you trying to corner the slide-rule market?” his wife, Susan Shawlee, asked him nervously, The Wall Street Journal reported in 2003.
The magazine of the Institute of Electrical and Electronics Engineers, Spectrum, determined in 2007 that Mr. Shawlee had, in fact, “cornered the world market.”
“He’s Mr. Slide Rule,” a Texas engineer and slide-rule enthusiast told The Journal. “Walter knows everybody in the slide-rule racket.”
Image
Mr. Shawlee in 2018. “He’s Mr. Slide Rule,” a Texas engineer and slide-rule enthusiast was quoted as saying. “Walter knows everybody in the slide-rule racket.”Credit...Sphere Research Corporation
Mr. Shawlee died on Sept. 4 last year at his home in Kelowna. He was 73. The death was not widely reported at the time, and The New York Times was notified about it only last month. His wife said the cause was cancer.
I still have my Hemmi slide rule that I used when doing my engineering in 1970 and still works like new. I also have a small 150mm one that I got from a SKF rep which was useful in the field. I remember using log tables before I got the slide rule which was a blessing but still had to use the brain to work out the magnitude so maths skills were still maintained.
So when all the chips die I can still do maths greater than the number of fingers and toes.
So when all the chips die I can still do maths greater than the number of fingers and toes.
i always thought slide rules were great in college because they forced the acquisition of better understanding of what you're doing.
i probably shouldn't say this to give away how old I am, but our first "real" EE project in school was to build a calculator from a kit they bought from Poly Paks. (Raise your hand if you remember them
) It was a race to see who could get one successfully completed first. Poly Paks was no HeathKit. But I finished first anyway. I gave it to my dad and kept using my slide rule. It was easy to tell the EEs around campus; we all had holsters for our slide rules; like gunfighters. kids ... LOL
i probably shouldn't say this to give away how old I am, but our first "real" EE project in school was to build a calculator from a kit they bought from Poly Paks. (Raise your hand if you remember them
) It was a race to see who could get one successfully completed first. Poly Paks was no HeathKit. But I finished first anyway. I gave it to my dad and kept using my slide rule. It was easy to tell the EEs around campus; we all had holsters for our slide rules; like gunfighters. kids ... LOL 
The thing about using a slide rule is that it gives you a better feel for what numbers really mean than when you use a calculator.
You had to have a ballpark idea of what the answer to the calculation was before you actually worked it out using a slide rule.
When calculators came along, some of the uninitiated users made the mistake of trusting what it said on the numerical display.
A slip of the finger on the buttons could lead to an answer that was magnitudes out, but which was blindly accepted!
The photo shows Buzz Aldrin using a slide rule while on the way to the Moon in 1969:
I almost forgot the book of log tables I used at school prior to my university slide rule days!
A delight for which I am eternally grateful to John Napier of Merchiston, Scottish landowner, mathematician, physicist, and astronomer!
Wow, thanks for posting this. RIP Walter.
I used a slide rule in high school and found it much faster and more capable than the first calculators that were showing up.
Switched to an HP-45 in college but always kept the slide rule handy in case the batteries died.
Was given an abacus in elementary school but never learned how to use it.
Later my Dad said I should learn, just in case I lost the slide rule.
The HP-45 batteries are long dead and the slide rule hasn't been seen in 50 years.
I do still have the abacus..... somewhere.
I used a slide rule in high school and found it much faster and more capable than the first calculators that were showing up.
Switched to an HP-45 in college but always kept the slide rule handy in case the batteries died.
Was given an abacus in elementary school but never learned how to use it.
Later my Dad said I should learn, just in case I lost the slide rule.
The HP-45 batteries are long dead and the slide rule hasn't been seen in 50 years.
I do still have the abacus..... somewhere.
Attachments
I still keep and sometimes use for kicks my old 1 foot (or so) Staedtler slide ruler, which I bought when I started Industrial Engineering in February 1969
No pocket calculators yet and we were taught Fortran to be able to use our big and clumsy IBM 1620; also Basic for everyday simple stuff.
Programs were kept in perforated paper rolls "written" on what looked like an Electric typewriter, no screens involved, and output was via a large noisy "line printer" on wide (20" ?) perforated edge fanfold paper "bedsheets"
Wr alone must have been responsible for destruction of a couple hectares of rainforest trees ☹️
Also a 6" or so pocket version and a coffee plate sized circular slide ruler which I often carry with me when buying electronic parts, much to the amazement of sales guys.
Very useful when some resistor or capacitor is missing, so I have to scale up or down other values, or instant power dissipation calculation, much faster than pushing keys.
A useful point many ignore, is that it does not give you one result but all the range of combinations meeting it, in front of you, in real time. Try that, calculators and computers!
No pocket calculators yet and we were taught Fortran to be able to use our big and clumsy IBM 1620; also Basic for everyday simple stuff.
Programs were kept in perforated paper rolls "written" on what looked like an Electric typewriter, no screens involved, and output was via a large noisy "line printer" on wide (20" ?) perforated edge fanfold paper "bedsheets"
Wr alone must have been responsible for destruction of a couple hectares of rainforest trees ☹️
Also a 6" or so pocket version and a coffee plate sized circular slide ruler which I often carry with me when buying electronic parts, much to the amazement of sales guys.
Very useful when some resistor or capacitor is missing, so I have to scale up or down other values, or instant power dissipation calculation, much faster than pushing keys.
A useful point many ignore, is that it does not give you one result but all the range of combinations meeting it, in front of you, in real time. Try that, calculators and computers!
You're sure to remember the image below.
With a circular slide rule one can boldly calculate where no man has calculated before!
I never liked very much slide rules or mathematical tables (and their inevitable interpolation process). Fortunately for me, it didn't last long before digital calculators appeared.
However, I did like nomograms (and I still do), and I even brewed one or two of my own. You could argue that nomograms are a sub-variety of a slide-rule, but for me the feeling is quite different
However, I did like nomograms (and I still do), and I even brewed one or two of my own. You could argue that nomograms are a sub-variety of a slide-rule, but for me the feeling is quite different
When I was in high school, Ohio Bell Telephone gave us a large quantity of Western Electric telephone relays. One of the guys made an adder, shifter, etc.i always thought slide rules were great in college because they forced the acquisition of better understanding of what you're doing.
i probably shouldn't say this to give away how old I am, but our first "real" EE project in school was to build a calculator from a kit they bought from Poly Paks. (Raise your hand if you remember them
I remember PolyPaks -- about the same time that DK had a 32 page catalog!
My slide rule is celluloid over bamboo, it's a "Sun-Hemi".
My Brother is a Commercial pilot, and he swears by his Jeppesen Flight Calculator, the within-Earth-atmosphere version of what Mr Spock is using
I almost forgot the book of log tables I used at school prior to my university slide rule days!
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A delight for which I am eternally grateful to John Napier of Merchiston, Scottish landowner, mathematician, physicist, and astronomer!
As I mentioned, I was on the cusp of the slide rule to calculator transition, so I learned to use log tables.
I've mentioned this before on this forum, but my Texas Instruments TI25 from school, circa 1979-80, is still working using the original button batteries. I find that quite amazing! If I used it for any length of time I guess it'd fail. But the batteries aren't leaking... I wonder what modern battery companies could learn from the seals used back then.