Musings on a Slide Rule

[Marshwheeling]

My high school physics teacher made sure we all knew how to use a slide rule, even though it had no direct application to most of what he taught. He just thought it was part of his task to impart this essential bit of knowledge to young men. I never did put one to any practical use.

In those days, the most-desired computational device was the Curta “pepper mill” mechanical calculator, the hot setup for sports car rallyes where you were expected to maintain a specified average speed over a complicated course. I could not afford one at the time, and only came into this one some years later. In the meantime, rallyists were soon using some very rudimentary computers, which before long obsoleted the Curta along with the slide rule.

 

[Rustyt1953]

William Oughtred was an English mathematician and Anglican clergyman. After John Napier (Scottish) invented logarithms and Edmund Gunter (Welsh) created the logarithmic scales (lines, or rules) upon which slide rules are based, Oughtred was the first to use two such scales sliding by one another to perform direct multiplication and division. He is credited with inventing the slide rule in about 1622. He also introduced the "×" symbol for multiplication and the abbreviations "sin" and "cos" for the sine and cosine functions.

You're bloody welcome.

 

[les.b]

Well...I've been thinking about my "best" slide rule, which was bought for me while I was in about the eighth grade by my cousin, who was in the Navy. He was doing a tour in Japan, and brought me home a beautiful bamboo slide rule. It was bamboo overlaid with a thick layer of some white celluloid material, which was machined perfectly. The markings and figures were engraved and inlaid with dark navy blue material, and then everything was finely finished so that all markings were flush with the white surface of the rule.

I think that it was called a "Sun Hemmi"? I remember that it came in a dark green case. Anyway, it was stolen from my mom's house many up years later in a house burglary.

But the thing about the bamboo vs other materials was that it was always at what seemed like the perfect degree of friction...it wouldn't slide on its own, but seemed to move effortlessly as you manipulated the scales!! I have handled other rules that used other woods for the core, but I think that bamboo was the perfect choice.

I have really enjoyed these reminisces and thoughts about the wonderful slide rule!! Certainly bring back smiles to those of us who learned to use them back " in the day"!!!

Best Regards, Les

 

[Pondoro]

That is great, I have my dad's old slide rule. I also bought a nice but well used attache case and researched the previous owner. No names, he died in 2012 and why heap pain on his heirs, who are probably still grieving? But I know he sold medical equipment and was a pillar of his church and community. His leather case now transports ukulele sheet music. His obituary is on-line and you can leave comments. I did not do it, but a little voice told me to leave a comment saying, "Dude, I've got your briefcase."

 

[swsig]

This is Dad's slide rule, a K&E Log Log Duplex Decitrig, Model 4081-3 (the O.P. has the older no-dash model ), complete with holster and belt loop. Dad got it to use in the Army's radar technician courses (which included college courses in Physics and Calculus) in 1942. I used it extensively during my junior year in high school when I had geometry, trigonometry, and chemistry classes. I look at it today and think, how did I do that?

 

[DWalt]

"When I was a young engineer, we needed to measure the area of an irregular shape on a drawing. One of the lead engineers was rumored to own a planimeter so we asked him if we could borrow it."

When I worked at Hercules, solid state electronics was in a primitive state of development. We would record the voltage vs. time output of piezoelectric pressure gauges on an oscilloscope equipped with a Polaroid camera to record the curve, then analyze the curve using a planimeter, integrating the area under the curve (basically pressure vs. time).

At one time I worked in an analytical chemistry lab. One instrument I used frequently was a gas chromatograph which was attached to an X-Y curve plotter. Our standard method of integrating the curve at that time was to take the tracing on paper and cut along the curve with an X-acto knife, then weigh the paper on a very sensitive analytical balance, then compare the weight to the weight of a square of the same paper having a known area. That allowed determination of the area under the curve. It worked well enough but it was slow. Later, we got an electronic curve integrator which calculated the area as the curve was being plotted, and that was much faster. My son, who has a degree in Chemistry, was amazed that analytical instrumentation and methods he used were once so primitive.

My K&E slide rule is identical to the one shown in #45. Except my carrying case is considerably more beat-up. I'd sell it on eBay, but it's probably not worth the effort.

 

[soFlaNative]

This thread means...

[ame]https://www.youtube.com/watch?v=MrCPIrs90eg[/ame]

 

[fordson]

After I retired, I worked as a contractor for a bit. I had a team of young engineers who never used, and in one case, never saw, a slide rule. I told them all to clear a two hour window in thier next day schedule for training. Next day I brought in my old K&E (circa 1968) slide rule and gave them a two hour fam course on slide rules. They were amazed and even more so when they learned, as someone here pointed out, that the Mercury and Apollo programs were designed and executed using primarily slide rules. And the icing on the cake was showing them my old Jeppesen “whiz wheel” Flight Calculator - for you non-aviators, the circular “slide rule” with the slide behind - that was used before electronics and GPS.
New technology supplants the old, but there’s value in knowing how we got to where we are.

 

[Walter Rego]

Well I had to dig out my dad's. It is a Keuffel & Esser Co. Model 4080-3. He was a Navigator on a B-24 with the 15th AAF before college and I imagine that he knew how to use all kinds of pre-electronics era mathematical tools including a sextant, compass, triangles and others.

 

[Drm50]

1968 was starting engineering at a branch college. Got a job in Eng dept
of mining co. Did it all on slide rules. Things were booming and dropped
some hours to make big bucks. Dept had just bought a HP calculator that
was about the size of period walkie-talkie, amazing. About 3 years later
when I came back all the little calculators the size of TV remote were out.
I still have my slide rules, drafting set and even ended up with old Buff
transit, direct read. Now very few people are taught use of the old instruments. They can't make change for a dollar without the digital cash
register. Now everything is still direct read, digital. I see some very fine
instruments for sale at yard sales & flea markets. Dirt cheap because they
aren't digital.

 

[Ματθιας]

I have a modest collection of slide rules, flight computers and calculators to go with some sextants that I've managed to accumulate over the years. I even have a pocket transit that I found at a yard sale for $10.

I'm self taught, thanks to the internet. I'm not a 100% sure I'm doing everything correctly.

The thing is, my dad was an old school machinist and tool and die maker with the railroad and offered to teach me how to use all of his mechanical tools and slide rules - but I was too young and arrogant to take him up on it. I thought calculators and computers were the only way to go. That's one of my biggest regrets.

I'll post picts if anyone is interested.

 

[BigBoy99]

IIRC it was 1988 and I needed to do some calculations. The several electronic calculators in the office were all in use so I dug out my slide rule and began cranking out the numbers. I was busy working away when I looked up and there were two newly hired engineers watching me. They said that they had never see a slide rule before, let alone some whom knew how to use one!

 

[les.b]

I have a modest collection of slide rules, flight computers and calculators to go with some sextants that I've managed to accumulate over the years. I even have a pocket transit that I found at a yard sale for $10.

I'm self taught, thanks to the internet. I'm not a 100% sure I'm doing everything correctly.

The thing is, my dad was an old school machinist and tool and die maker with the railroad and offered to teach me how to use all of his mechanical tools and slide rules - but I was too young and arrogant to take him up on it. I thought calculators and computers were the only way to go. That's one of my biggest regrets.

I'll post picts if anyone is interested.

I'll bet we are all interested. Lots of folks who appreciate fine old firearms also like fine tools of all sorts!! It's amazing how the older we get, the smarter our dads become!! Mine has been gone now for many years, and I'm still learning stuff he tried to teach me years ago. If that makes sense.

Best Regards, Les

 

[Golddollar]

And the icing on the cake was showing them my old Jeppesen “whiz wheel” Flight Calculator - for you non-aviators, the circular “slide rule” with the slide behind - that was used before electronics and GPS.

I remember those old flight calculators. When my dad was going to ground school for his private pilot's license he took me along and I studied about them. And Pop would refer to it as a circular slide rule to help me understand what it was.

Forgive me for gushing a little bit, but this thread about slide rules with the side discussion about drawing tools brings back what was a major part of how I made a living for many years, and earned for me a lot of respect from my colleagues. I used to give lectures to the agents of the title insurer I worked for about how land was measured and how parcels of land were described, including old measurements like "links" and "chains." The running gag in my department at one job was how everybody new had to go through my "Chain, Compass and Protractor School", complete with diploma. To me it was important to make sure that others in the firm had these skills and I was happy to make sure that these old time skills were kept alive and passed on.

 

[DWalt]

The very first "personal" electronic calculator I saw was also around 1968. It was fairly large, as I remember about the size of a shoebox. And it was horrendously expensive for the time, about $5K. It had some limited programming capabilities. I wasn't allowed to touch it, and it was kept locked away. You needed special permission from the boss to use it. The first calculator I personally used was a TI, in the early 1970s. Someone in the office bought one. I know it was somewhat over $100. All it did was add, subtract, multiply, and divide. Amazing when you consider that a scientific calculator will cost you $1 today at the Dollar Tree. And it's a pretty good one. I have one of them.

I was Director of Engineering at a large oilfield service company back in the early 1980s, and I couldn't get authorization to buy one of the then-new IBM PCs, which at the time were around $20K. I did buy several of the earlier Timex computers, not very good but better than nothing. Remember programming with FORTRAN?

 

[Drm50]

A few years ago I bought a Sexton in case with accessories and
set of filter lens. $5 at a auction, I was only one that bid. It
turned out it was Army Air Corps out of B-17 bombers. I gave
it to a buddy of mine who was donating items to the 8th Air Corps museum they were starting up in Savannah, Georgia.

 

[swsig]

...And the icing on the cake was showing them my old Jeppesen “whiz wheel” Flight Calculator - for you non-aviators, the circular “slide rule” with the slide behind - that was used before electronics and GPS.

There was also a "simplified" flight calculator. The one I've attached below (with the instruction sheets) belonged to my wife's older brother, a C-46 pilot who flew supply drop missions to front line troops in Europe during the last months of WW2. He survived his missions though his plane was holed by enemy fire several times. If that calculator could only talk...

 

[rwsmith]

I've wondered that too.....

I still use a slide rule.
Have a aluminum Pickett in the truck for gas mileage calculations, memories and causing confusion.

Late 70s the University Bookstore at University of Arkansas was having a CLEARANCE SALE selling slide rules for $5.00.
Three of us older fogies ran over and bought some extra POST VERSA LOGS - just for the memories.

Do any of the Asians still use the abacus ?

Bekeart

Watching somebody really good with an abacus is amazing. I hope that it isn't a lost art.

There was a Monty PYthon sketch where aliens were turning English people into Scotsmen because it was the only way to win the tennis championship. "After all, the Scots canna play the tennis to save their very lives."

Switch to a Scottish men's wear shop.


American Voice Then suddenly a clue turned up in Scotland. Mr Angus Podgorny, owner of a Dunbar menswear shop, received an order for 48,000,000 kilts from the planet Skyron in the Galaxy of Andromeda.
Mix to interior of highland menswear shop. An elderly Scottish couple are poring over a letter which they have on the counter. Oil lamps etc.
Mrs Podgorny Angus how are y'going to get 48,000,000 kilts into the van?
Angus I'll have t'do it in two goes.
Mrs Podgorny D'you not ken that the Galaxy of Andromeda is two million, two hundred thousand light years away?
Angus Is that so?
Mrs Podgorny Aye ... and you've never been further than Berwick-on-Tweed...
Angus Aye ... but think o' the money dear ... £18.10.0d a kilt ...

(He clicks an abacus about three times)

£900,000,000 - and that's without sporrans!
Mrs Podgorny Aye ... I think you ought not to go, Angus.
Angus (with visionary look in his eyes) Aye ... we'd be able to afford writing paper with our names on it... We'd be able to buy that extension to the toilet...


Anyway, I think the idea is that the Scot's can't play tennis, but they can sure count money.



OK, TO STAY ON TOPIC:

I have/had a K&E slide rule, but it was aluminum and not a piece of art like that one. It had a long black leather holster that all of the tech students wore on their belts around campus. Later, when I worked at the VA hospital I had my name badge on a pocket protector full of pens/pencils I used. That way when I came in, I'd just slap in my pocket protector with the badge already on it, No one had started using 'Nerd' or 'geek' much, so I was pretty innocent.

In fact I had some old well made drafting instruments around, too.

I took the last required class of slide rule, but NOBODY could afford the first calculators. Until a guy bought one that could add, subtract multiply and divide. And we thought that was the greatest thing since sliced bread. By the next year calculators were more affordable and they dropped the slide rule requirement.

When I got my first 'real' job' one of the engineer got a TI-59!!!!! (with the magnetic strip program reader) I mean the Rocket Age was really on it's way. Actually, many of my professors were laid off NASA engineers. It was that time in the 70's.

 

[steveno]

my first good calculator was a HP-41CV and for what it could do it was also my home computer for a number of years.

there was a HP-41 users group that where you could submit programs and if the group thought the program had merit they would include in the next list of programs and it would also have it converted to bar code for easier entry into the calculator. I had one of the ballistics programs and it would have taken forever to enter it using keystrokes but took about 10 minutes using the bar code reader. I also used it at work with the mechanical engineering and extended functions modules. a few years ago it stopped working and new batteries didn't fix it. it is was one of the best calculators ever made.

I still use HP-11C and 12C calculators. I'm so used to using RPN that I get lost when I see a calculator with an "=" sign


HPCC : HP-41C/CV/CX

 

[DWalt]

I always wanted a high-quality cased sextant to go with my WWII Hamilton marine chronometer just as a curio but I never bought one. As with slide rules, there's not much need for sextants and chronometers today as even the cheapest GPS device is far more precise (and much simpler) for determining latitude and longitude.