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Another Unusual Heirloom


Joe Frickin' Friday

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Joe Frickin' Friday

A couple of years ago I wrote about inheriting my dad's workbench. My dad is still around, but he and my mom had to unload the workbench and a bunch of other things back then when they moved from their house to an independent-living retirement community. Last year when they moved to an assisted-living community, they downsized their belongings a little further, at which point my dad gave me his slide rule:

 

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Dad bought this back in 1951 when he started college at the University of Massachusetts. By the time my older brother and sister started high school, portable electronic calculators were available and affordable, but only just barely; slide rules were the order of the day until the mid-1970's. We here in 2018 are spoiled by the immense computing power of our smart phones and iPads, but looking back, it's amazing to realize that the biggest achievements of the Industrial Age – things like the steam engine, the Wright Flyer, the Hoover Dam, the Empire State Building, the Panama Canal, the Golden Gate Bridge, the Saturn V, the Boeing 747 – all owe their existence to the slide rule.

 

Since this was the first time I had actually handled a slide rule, I was pretty curious about it. After taking it apart to clean and re-lubricate it, I did some Googling. This being the Information Age, the internet is all about connecting curious souls with obscure information – and sure enough, I quickly landed in the International Slide Rule Museum, which appears to have gathered absolutely everything there is to know about slide rules. They even have a tutorial on how to use a slide rule, which includes a virtual slide rule you can fiddle with if you don't have a real one.

 

As the tutorial shows, there's an amazing amount of functionality packed into a device with only two moving parts: multiplication, division, inverses, roots, powers, trig functions, logs, and so on. The interesting thing is that for many of the functions, the slide rule only works with numbers between 1 and 10 – it's up to the user to strip away all the tens, use the slide rule, and then put the decimal point in the right spot afterwards. So for example, you can't multiply 427 * 92 directly with the slide rule; instead, you multiply 4.27 by 9.2, the slide rule says “3.93”, and you have to remember to move the decimal point four places to the right to get 39,300. Although this is a pain in the ass by modern standards, slide rule historians (and a few very senior engineers who are still out in the work force) claim that this makes the user THINK about the magnitude of things and develop a common-sense grasp of whether the answer is in the right range or not (“400 times 100 is 40,000, so my answer should be near 40,000…”). A friend once taught an undergraduate engineering class, and lamented that his students often wrote down answers without pausing to think whether they made sense (e.g. a cruise ship traveling at 89 MPH, or an engine efficiency of 105%); maybe those kids would have fared better if they had been forced to use a slide rule instead of a pocket calculator!

 

For 427 * 92, a digital calculator gives the exact answer as 39,284, but your eyeball can't read such fine tick marks on a 10-inch slide rule; three significant digits (39,300) is generally the best you can do. Now you can understand why larger slide rules are more precise: you're stretching the 1-10 scale over a greater distance, so you have more room to fit/see tick marks that indicate more and more digits after the decimal. The world's longest slide rule was over 350 feet long; with all its extra tick marks it was able to directly indicate 5 significant digits, with the user estimating a sixth digit. Going in the other direction, there are six-inch slide rules out there, too – less precise, but more portable.

 

The Slide Rule Museum gives a detailed history of the various manufacturers and models of slide rules. Dad's slide rule was made by Pickett:

 

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From the museum's Pickett history page/gallery, I was able to learn that Dad's slide rule is a model 3-T, with ten-inch scales. Pickett's unique claim to fame (and advertising point in the final few years of the slide rule's 350-year reign) was that their slide rules went up on the Apollo missions. Here's a Pickett catalog cover from that era:

 

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Note the splash in the upper right corner:

 

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The hype carried through to the packaging for their slide rules as well:

 

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Anyway, a neat piece of engineering and family history, now proudly displayed on my office desk:

 

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Can't find it in that pic? Look in front of the computer monitors:

 

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A little lower…there it is:

 

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There are still some gray-haired engineers around the lab who remember earnestly using a slide rule in high school – and there are also occasional student interns who have never seen (and sometimes never even heard of) a slide rule before. Having this out on display makes for a fun conversation starter.

 

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Thanks Mitch for sharing with us that great memento from your father as well as an excellent overview of an object that many of us have never seen, let alone knew how to use.

 

In the 70's, my father bought a 4 function Rockwell hand held calculator and he was so proud! Times they are a changing.

 

Then we thought we were pretty early adapters when we bought an Atari 400 computer with tape storage and dot matrix printer. :dance:

 

 

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Mitch what a coincidence, About a month ago my niece was helping my mom clean out a closet. She came across my dad's slide rule from college, business major not an engineer. Went to school after Korea on the GI bill graduated in '56.

 

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Danny caddyshack Noonan

I had a Picket in high school probably until 1975 and didn't have any math in my senior year. I waxed it a bit to allow the high-performance fling maneuver in study hall. Decided against an Engineering degree after about a year in college. Became a cop instead because they don't have to do math or trig, NOT! 20 years later, I had to have a graphing calculator to complete the math curriculum.

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Joe Frickin' Friday
I waxed it a bit to allow the high-performance fling maneuver in study hall.

 

OK, I'll bite. What's the "high-performance fling maneuver"? :lurk:

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Slight hijack: Good for your old man for giving it to you, and down sizing, and moving into some kind of retirement outfit. He is to be congratulated.

 

My old man had a box full of slide rules. And a basement full of everything else you can think of (for instance, there were 350 antique cameras). And NONE of it was allowed to depart prior to his death. So here we are, having to sort through his hoard. He had the whole spectrum from valuable antiques to genuine garbage. And we have to figure out what's what. Some advice: Don't make your kids clean up your mess after you're gone.

 

End of hijack.

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It was the badge of those in higher MathSciencey track.

 

Pocket protector, cartridge ink pen tucked next to it.

 

Used it for years.

Never learned the hand held replacement calculators and yes, you had to t h i n k about the

relationship of numbers and values.

 

Went to a 2 week Physics camp about 10 years ago.

I was getting approximates like your example above before the calculator crew got close,

in my head.

 

I think it should still be tied to abacus - slide rule- calculator regimen for better number concept foundation.

Today's students too often GIGO.

 

Leather protector is a real treat to see.

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"Biggest achievements of the Industrial Age" shouldn't be mentioned in this context without bringing up the SR 71 Blackbird! It still befuddles me how they pulled that off............

 

I agree that you stand to lose something in the transition from analog to digital. Not just in music, but in "feel" of developing or even machining a product. But, with digital, you can realize your mistake and make several more mistakes until you get it right, long before the analog project is near finished.

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Met with a client once who had an abacus, I had a new financial calculator. We needed to solve a future value calculation, by the time I entered all the info into the formula she had the answer on the abacus. Fascinated me, maybe old school is faster and better!!

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Awesome. My dad was old school. gradated in1936 with a degree in physics from U of IL. He always carried a slide rule with him.

He had lots of old school stuff like that. Best was a 3 beam scale he used in chemistry class made by the Chicago Scientific Company. Very cool. :thumbsup:

I was able to get that and pass it on to my son who's a chem engineer. The rest of dad's stuff like slide rules, other chem stuff the wicked step mother wanted to keep with her. :( What she will do with it is a big question but when she dies if there is anything left of my dad's possessions they come back to me. As most of his generation he had kept everything. I'll need a dumpster for sure.

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Wow, you're lucky to have such a momento - it will become more and more important to you through the years. If I would have inherited something from my father it would have been a 1/2 second K&E transit. :-)

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Lone_RT_rider

My friend,

 

You have to be careful about keeping such museum pieces (relics) at your desk. Your getting older sir. One of the interns with a wicked sense of humor might just call something else at the desk....a relic. ;):D

 

And yes, I know I am older than you. :dopeslap::facepalm:

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Joe Frickin' Friday
My friend,

 

You have to be careful about keeping such museum pieces (relics) at your desk. Your getting older sir. One of the interns with a wicked sense of humor might just call something else at the desk....a relic. ;):D

 

And yes, I know I am older that you. :dopeslap::facepalm:

 

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Lone_RT_rider
My friend,

 

You have to be careful about keeping such museum pieces (relics) at your desk. Your getting older sir. One of the interns with a wicked sense of humor might just call something else at the desk....a relic. ;):D

 

And yes, I know I am older than you. :dopeslap::facepalm:

 

2018-09-slyde-roole-09.jpg

 

 

animated-laughing-image-0133.gif

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Danny caddyshack Noonan
I waxed it a bit to allow the high-performance fling maneuver in study hall.

 

OK, I'll bite. What's the "high-performance fling maneuver"? :lurk:

 

Slide the insert about 1/3 of the way proud of the end and flick the slide rule causing the insert to fling across study hall.

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Mitch, when sorting out the chattels of my late brother's estate not only did I come across his assortment of slide rules but also his Curta Calculator. This is a fascinating little pepper mill shaped device (it even has a crank on the top) that was thought would take over from the slide rule until the electronic calculators intervened so they were short lived. You would have a hoot learning to operate one. Like the slide rule they've now become a collector's item.

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I showed the slide rule to my 14 yr old. I did some reading and figured out how to calculate square roots, he thought it was the coolest thing, an analog computer!

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Like a lot of the other old codgers here, I used one of those all thru school. Mine was a Pickett too but a little smaller model (I still have it). Some of my EE buddies preferred the bamboo models (I think Pickett made them too) because they wouldn't short things out if you accidentally dropped them into a working electrical circuit (a guy I knew actually did that and ruined both his slipstick and the circuit). I eventually replaced mine with a Heathkit four function calculator...I still have it too.

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Joe Frickin' Friday
Mitch, when sorting out the chattels of my late brother's estate not only did I come across his assortment of slide rules but also his Curta Calculator. This is a fascinating little pepper mill shaped device (it even has a crank on the top) that was thought would take over from the slide rule until the electronic calculators intervened so they were short lived. You would have a hoot learning to operate one. Like the slide rule they've now become a collector's item.

 

Had never heard of a Curta until seeing your post. This is really cool! You aren't kidding about these things being collector's items. :eek:

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  • 3 weeks later...

Very cool Mitch. I have a couple from my grandfather and you've inspired me to figure out how to use one.

 

Eric, I know that story myself. Very hard for some to let go of stuff when that stuff represents memories, dreams or regrets.

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I still have my bamboo Post which was purchased in 1968. A slide rule class was required in the first semester for all engineering students where I went to school. I love to show the grand kids how it works.

I worked at an electronics/audio store in college. Back in 1969 Craig came out with an led add/subtract/multiply/divide hand held calculator that originally sold for about $250. In today's dollars that would be $1700. The price quickly dropped to $179 which is still $1200 today.

We also used real analog computers to simulate mechanical systems with electric circuits. Resisters were springs, capacitors were shocks, etc. You could study the response with an oscilloscope.

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... ... ...

 

I think it should still be tied to abacus - slide rule- calculator regimen for better number concept foundation.

Today's students too often GIGO.

 

Leather protector is a real treat to see.

 

(entering the conversation late; missed it first time around)

I took a summer time class between 4th and 5th grade with math and science curricula. In the math side I learned among other things first the abacus and then the slide rule. I owned a few. I have no idea what happened to them. Being a keeper of stuff, they wouldn't be something I would have gotten rid of. But either I left them behind somewhere or have them in one of my old "keep stuff" boxes. Maybe I'll go search a bit. . .

 

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I have a sliderule - built into the bezel of my watch!

Now, I grew up in the age of pocket calculators, but my father had a slide rule from engineering school, and being the little nerd that I was - I learned to use it. So when I got my watch, I had to show the sales clerk what it was, and how to use it.

Here's a video that does a better job of that task:

Edited by Gregori
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when i was taking engineering , one of our Profs had a BIG one hanging in the class, think 4 ft long...

 

i still have two,

 

Oh have you ever heard of a Curta calculator... hand crank.. got one of them tooo.... used for time/ distance autorally befor the electronics took over

Edited by SANTA
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Joe Frickin' Friday
Oh have you ever heard of a Curta calculator... hand crank.. got one of them tooo.... used for time/ distance autorally befor the electronics took over

 

Rocer mentioned these upthread, and I've been kind of fascinated with them ever since. If I ever manage to dig up $1000+ from my couch cushions and my car's ashtray, I might go after one on Ebay someday.

 

For anyone else who hasn't looked them up, here's a few worthy links:

 

First, the Wikipedia page for the Curta.

 

, with two guys discussing the Curta and explaining/demonstrating its functionality.

 

If you get through this whole video, you'll come to appreciate what a freakball mechanical genius its inventor must have been to conceive that thing in his head. :eek:

 

This was a gift from someone else. 3D-printed plastic doesn't have the dimensional precision required for a normal-sized Curta, so he scaled up the size of everything until the available precision was adequate; the final product ended up being the size of a coffee can.

 

 

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unbelievable, ! i paid $100.00 back in 1977 for mine.

 

Do you still have it? That's like a 200% return (over 40 years....minus any storage or maintenance costs....plus any income generated by ownership)!

 

sure its sitting on my old tech shelf in its container

 

Very cool! (And another couple hundred years and you can sell it and retire. Again.)

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I would be happy to buy it and give you a 200% rate of return. :wave:

 

I was adjusting value for "today's" dollar - hopefully you'd be making the same offer. :)

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well lets see what the one on ebay goes for, but the cost of storage and what with inflation i'm not sure 200% is gonna cover it, its sort of like a nice r100rs in mint condition under 500mi now is worth a lot more than in yesteryear...

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