When Slide Rules Were Like Cellphones (hackaday.com) 220
szczys writes: Slide Rules and Pocket Protectors are the go-to items when making fun of old-time geeks. Forget the pocket protectors. Slide Rules were the first personal computers and a status symbol akin to what cellphones are today. Of course the general public wasn't attached to them, but engineers were. Before electronic calculators came around, everyone who needed to do some serious math owned Slide Rules. Stunningly easy to use and extremely effective, they have tick-marks placed on a logarithmic scale which makes complex multiplication, division, powers, etc. into visual calculations instead of mental ones.
Still got mine. (Score:2)
Didn't have calculators when I was finished high school (year 12).
Still in it's plastic cover with the manual.
Drag it out now and again just for a laugh.
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Me too. Three in fact. Inherited them from my grandparents ... and I can actually use them -- to a small extent. Don't have any manuals though.
More than logarithms (Score:5, Interesting)
there were lots of possible slide bars. Ones for trigonometry, etc.. Most of the boeing planes up to the 747 were made by engineers who still used slide rules. Sure there were calculators and computing machines too, but slide rules were still in use by old timers.
Verniers (Score:5, Interesting)
The digital caliper replaced the analog caliper. I miss the vernier scale, a really clever invention to squeeze out one more digit of precision than one would think possible. I doubt most kids today have any idea what a vernier scale is. The differential micrometer is another very clever device which works like a mechanical version of the vernier. My guess someone thought of it after seeing a vernier scale.
Re:Verniers (Score:4, Interesting)
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My main calipers and micrometer are Starrett analogs. I like not having to replace the battery or having the value jump if your battery is low. I bought them for myself when I graduated college about 20 years ago. They cost about $400 today.
Re: Verniers (Score:2)
Why the hate for digital? (Score:4, Interesting)
I have Starett analog caliper and micrometer, and another Starett analog caliper in metric. I HATE digital calipers.
Other than the battery issue I don't really understand why you would dislike digital calipers. Our shop uses both analog and digital. The ONLY real advantage to analog is that you don't have to change batteries ever, which for some situations is nice. Otherwise the calibration procedures are the same and they work similarly effectively. Digital ones in my experience tend to be modestly easier to use but the difference is very minor outside of some specialty applications.
If you get drawings in both metric and US customary like us, carrying two measuring devices quickly becomes tiresome. Digital can switch between with a press of a button which is nice. Digital calipers can also output readings to a computer directly which can be really handy if you do a lot of it for stuff like PPAPs. There's nothing wrong with a good analog measuring device but there's nothing wrong with a good digital one either.
Re: Still got mine. (Score:2)
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You'll pry my slipstick from my cold, dead, hands!!!
Re: Still got mine. (Score:2)
hence the old joke... (Score:4, Funny)
(Disclaimer: I used a slide rule in high school in the 1970's, and we actually had a section of a class in how to do so)
Person A: "What's 2 times 2?"
Person B: "Let me check my slide rule, one sec... OK, looks like around 3.96."
Re:hence the old joke... (Score:5, Insightful)
New joke
Person A: "What's 0.1 + 0.2?"
Person B: "Let me check my computer, one sec... OK, looks like around 0.30000000000000004."
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Welcome to the secret robot internet!
Re:hence the old joke... (Score:4, Insightful)
10.0 times 0.1 is hardly ever 1.0.
-- Kernighan and Plauger, The Elements of Programming Style
Re:hence the old joke... (Score:5, Insightful)
This reminds me of something said by a very wise Professor I had in grad school. I "go back a ways" and I was in grad school just as electronic hand held calculators were beginning to appear, and slide rules were in their last days.
The Prof declared that the new calculators were an efficient way to calculate the wrong answer to a high degree of precision.
In other words, whether calculator, slide rule, computer, or whatever device --- none of them substitute for knowledge and judgment.
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Re:hence the old joke... (Score:4, Informative)
I know it's a joke, but I actually read the article and used the online web simulator to work though the example problem that the article suggested. It was a very simple problem... What is 2 times 3. Obviously, any grade schooler can tell you the answer is 6, but using the slide rule as accurately as possible, I came up with 5.5. If that's an example of the accuracy of a slide rule, then good riddance!
I wouldn't say that's an example of the accuracy of a slide rule. Rather, I'd say it's an example of your lack of skill with one.
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Ditto. I gave it a quick try, and was pixel-perfect.
Just following the instructions on the website was all I needed to get the right answer. I can't imagine how bad you have to be to not get the right answer...
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I'd rather have an HP-41C. Even without the card reader.
But I would settle for my Pickett rule. Yellow aluminum, leather case, magnificent to me in high school. Dropped it once, not a bit of alignment problems. At the time the attraction was it was the longer version of the one sent up on Apollo missions, or something like that.
And multiplying 3 x 2 gave the answer 6, with sufficient precision to be useful. Only an idiot would multiply two whole integers and not discard the apparent decimals... Multipl
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The first three numbers on the bottom of the slide are 9, 1, and 1. The second one is really 1.1 (as you can guess from the progression up to another 9, and then 2), and if you line that one up you end up with 5.5, because the real "1" is down around 1.81 (so 3*1.81=5.43). You need to line the first 1 up with the 2. Then everything lines up perfectly.
I had basically the same confusion the first time I tried. After figuring out which was correct, it was neat to see any multiple (eg: 1.5, 2, 3, etc) all g
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Why aren't you using the A and B scales?
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User error, you mistook the tenths marks for the ones, so you (accidentally) calculated 1.2*1.3 and got 1.56.
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1 part in 1000 is 0.1%- good enough for most things you need to calculate. It got people to the moon and back. If your engineering depends on some digit 13 places past the decimal place, your engineering sucks.
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Expensive slide rules sometimes get to 4 digit logs with very fine rulling and very long slide bars. But some manage to get extra precision using a vernier scale. You should see if yours has a vernier on it, most do. It's a clever trick.
engineering precision. (Score:5, Insightful)
Indeed, small difference of large numbers is only a problem for computers who brute force things. Quad precision is for wimps. Engineers had lots of tricks for re-writing equations so that the terms would naturally sum to a small number without large intermediates. I recall learning 4 different ways to write the quadratic formula that would avoid cases where b^2-4ac was the difference of large numbers or -b + sqrt(b^2-4ac) was the difference of large numbers. Since comuters I don't think I've ever seen that used. it's always coded with the textbook -b + sqrt(b^2-4ac). This is also why many eignenvalue algorithms give signular results in modern compuations. People don't spend the time to figure out how to avoid those precision level differences.
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News flash: Computers do that, too.
Many transcendental functions are the result of some sort of series formula and most of them have values where the series converges very rapidly or very slowly.
To get the most precise answer in the minimum amount of time, the computer implementations of these functions pull exactly the same sort of tricks to fold computations over into the fast zone.
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You bought a cheap and small one.
Deviating slightly (Score:2)
This is all well and good (Score:4, Funny)
But how can we use slide rules to encourage women and minorities to join STEM fields?
50 Shades of Slide Rule (Score:4, Funny)
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Use it as a paddle?
Sure, as long as you're on the receiving end first. :-P
'scuse me, your mom and I are busy.
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Make them in pink with pictures of Violetta.
What about Log tables (Score:2)
I was in high school in the early 70's
We spent way more time using 4 digit log (and trig) tables than slide rules
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I finished highschool in the mid-90's and we also used 4 digit log and trig tables more than anything, it was the following year I think '95 or '96 that they started allowing students to use calculators as long as they had no graphing function, but you couldn't use them in exams. I think it was in my sisters last year in highschool around 2000ish that they allowed graphing calculators, and you could use them in exams.
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I used a calculator in my "A" level maths exam (high school) in 1975. I Think that it was an TI SR-50. It made some of the questions remarkably easy -- I think that the people who wrote the exam paper did not realize that calculators could "do" logs.
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I used a calculator in my "A" level maths exam (high school) in 1975. I Think that it was an TI SR-50. It made some of the questions remarkably easy -- I think that the people who wrote the exam paper did not realize that calculators could "do" logs.
Gotta chuckle at that, my dad was in university then. Can't remember if he was at UCR or KSU in '75 but they didn't allow calculators then but they did allow slide rules.
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it was the following year I think '95 or '96 that they started allowing students to use calculators as long as they had no graphing function
I remember having a TI 30 series (early LCD model) in 80/81....in 8th grade with the famous Great International Math on Keys book. It eventually died and was replaced with a Sharp EL515S in high school. I think I still have that one around somewhere.
Calculators were allowed in class, sometimes for tests/quizzes. Usually allowed for Finals, but you had to show the work so they were mostly used for double checking.
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Though I guess mostly I just memorize that 3dB (10^0.3) is ~2, 5 is ~pi and 10 is 10. One rarely needs to know the mantissa better than that
Log tables for the win! (Score:2)
I had both the school issued smallish slide rule and one I had inherited from my father which was much nicer.
However, I used log tables when I wanted even more accurate answers: One year my main wish on my Christmas list was a book that provided full 5-digit log tables. :-)
After I read about Taylor series I realized that I could calculate anything to any accuracy I wanted, but it still took a couple of hours (high school physics class) to calculate pi by hand with 20+ digits using the arctan formula.
(At thi
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In my town the local predecessor to Wal-Mart sold little Dennison pocket guides for maybe $1.00 each (it was a LONG time ago, you nasty little lawn-walker!)
One of my favorites was a book of tables with 6-digit precision. Loved the symmetry: Log 2 = 0.301030!
Cell phones today are a status symbol? (Score:3)
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Rocket scientist gave bad advice ... (Score:3, Interesting)
Decades later while cleaning up I found it and brought it to work to show my fellow geeks, software developers. The CEO was passing by my office and noticed the crowd, poked his head in to see what was going on. He ended up staying about 15 minutes alternating between the manual and slide rule to figure out how to do different calculations.
Everyone was just so impressed with what a few sticks with tick marks painted on them could do. Hell, its how we built the machines that got us to the moon.
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An uncle was an honest-to-god rocket scientist. Things he built are sitting on the moon right now. When I was in elementary school he gave me a slide rule and told me I needed to learn how to use it. Pretty bad advice. :-) Within a couple of years, and before math classes could have used a slide rule, inexpensive 4 function electronic calculators arrived at the local department store. And each year's new offerings were much more capable.
I wouldn't say it was bad advice. Learning how to use a slide rule helps you learn how logarithms work. You have a tangible visual representation of them right in your hands. Of course, you wouldn't keep using them for extensive calculation once something better comes along. But there's still something to be learned from slide rules, even if you don't keep using them. Just like there's something to be gained from learning arithmetic even though calculators can do it for us.
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An uncle was an honest-to-god rocket scientist. Things he built are sitting on the moon right now. When I was in elementary school he gave me a slide rule and told me I needed to learn how to use it. Pretty bad advice. :-) Within a couple of years, and before math classes could have used a slide rule, inexpensive 4 function electronic calculators arrived at the local department store. And each year's new offerings were much more capable.
This reminds me of my undergrad days. I am much younger than the slide-rule generation, but I had a physics professor (astrophysicist, so almost a rocket scientist) who grew up at the end of the slide-rule generation. Every week he'd have an extra "help session" during office hours. I didn't need the extra help, but I went anyway just to see the guy work -- it was a joy to see all the different ways he'd find solutions to problems. (And he always brought cookies.)
Anyhow, what always amazed me was his
We were the cusp generation (Score:5, Interesting)
First some backgroung: Slide rules only give the characteristic of the answer not the mantissa. It is a fancy way of saying, it does not tell you where to place the decimal point. Thus often people fly through the slide rule all the way, without doing the decimal points for intermediate answers. Once you have the final answer, you eyeball the number, see which decimal point would be reasonable and jot it down. Saving valuable time not doing decimal work, during examn time.
This was the point that prof made: He would set up the problems in such way the answer would be off by a factor of 10 on purpose. A 230 volt, 10 cm dia motor would come in at 75 watts. But people who don't do decimals would write down 750 watts because, that is the reasonable answer for such a machine. Thus he would know which students have a feel for the numbers and answers and who blindly follow the procedures and write down whatever answer comes out of the formula. His complaint was that he lost a valuable filtering tool to judge which students are worthy of being considered for RAships.
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Jeppesen (Score:5, Informative)
The Jeppesen CR-3 Flight Computer is a circular slide rule that is still in use today. The circular slide rule has long been a tool of pilots, air traffic controllers and even bookmakers! It's not just science types that use slide rules.
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Also known among pilots as prayer wheels.
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A better known example is the E6B [wikipedia.org]. Even used on screen (for its intended purpose!) by Mr. Spock in more than one original series Star Trek episode.
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A better known example is the E6B....
The pilot slang term for the E6B was "Wiz Wheel".
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Asimov taught me (Score:5, Interesting)
I stole a copy of "Why a Slide Rule Works" from the high school library and was way ahead of my math class the following year on logarithms & exponents. Asimov was a pretty good teacher.
I still have a Post VersaTrig around here somewhere...
Yes, and no. They were nice. Let's not exaggerate. (Score:5, Informative)
There are many examples of fine old technology that can be admired for the ingenuity that went into devising non-digital solutions, and that depended on being precisely made.
Slide rules were nice. They were a working tool for just about a century, very roughly 1870 to 1970. There are always some virtues to old technology that are lost when it's supplanted by new--the discipline of keeping the characteristic in your head and never losing track of the order of magnitude, the freedom from the illusion of precision.
They were only mildly status symbols, at least at MIT during the 1960s. There was a certain amount of discussion of the comparative merits of Keuffel & Esser (wood) versus Pickett & Eckel (aluminum), whether it was better to fold the scales at pi or at the square root of ten, and so forth. Plenty of people got by with cheap slide rules. I never heard of any cases of slide rules being stolen.
Keeping them properly lubricated, keeping the scales aligned, keep everything tensioned just right so that the slide and the cursor would move easily when you slide them and then stay put when you stopped pushing was a bear. More than once, people were embarrassed when the slide would actually slip out of the slide rule and clatter on the floor.
When I saw my first HP-35 pocket calculator, $295 IIRC, I said "There, at least, is something that I'd accept in place of a slide rule--if you promised me it would last for decades and never break.
Yes, I feel some nostalgia for slide rules--but let's not exaggerate.
Oh, by the way--that "2 x 2 is 3.96" joke above is wrong. On an exact answer like that, on a well-made slide rule if you put the index of the C scale over 2 on the D scale--and you can get it so that it looks perfect, and the eye has darn good vernier acuity--the 2 on the C scale will be perfectly aligned with the 4 on the D scale. You would read it as "4." You couldn't possibly read it as 3.96, 3.96 is two full scale divisions away from 4.
The problem comes when the answer lies between two scale divisions. For example, 3.98 and 4.00 are two adjacent marks. You would be hard-pressed to tell whether an answer were, say, 3.99 or 3.993.
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Once saw ... (Score:2)
.... Werner von Braun's slide ruler in a display case. It was exactly the same one that my grandfather used to own, and that I got to play with when I was a little boy.
Was using one in the late 90's ... (Score:2)
The use of calculators were strictly forbidden in my physics courses during the late 1990's, so I asked my instructors if I could use a slide rule during exams. They said yes, so I did. It was a lot of fun to whip out that slide rule on an otherwise stressful day.
Still have one. (Score:2)
The cheapo models were made of plastic, but the debate at the time was whether the best models were of bamboo or magnesium construction. Mine is made of bamboo. There was also an elitism factor - how many scales does your slide rule have? Whether you used them or not was irrelevant.
The one thing slide rules do not do naturally is plain old addition and subtraction. There are multiple hacks (e.g., antilogs) and it was a competitive challenge to find the "best" way. Seem to recall that my method used the
An excellent gadget (Score:2)
Yeah, slide
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I stunk at any kinf of math before seeing a lside rule,
And it would appear that I still stink at spelling.
A funny story about a slide rule (IBM manager) (Score:5, Interesting)
My father, Jack Harker, was a very senior manager at IBM. He was Director of the San Jose [IBM] Labs in the 70's and 80's. He was also one of the quiet giants of the disk drive industry convincing IBM upper management to develop thin film disk heads and the original Winchester technology.
Jack loved to tell how in high level presentations when lots of figures and projections were being put up on the screen and the numbers didn't seem right, he would reach over and pull out his old 16" ivory K&E slide rule from his college days. The younger managers and engineers who had not seen him do this before would be flabbergasted, quite often offering to get him a calculator. He did this for two reasons. The first was to flummox the presenters and push them out of their comfort zone. The second was that he found a slide rule with its logarithmic scales was very useful for visually looking at growth projections. A quick look to see if the numbers actually made sense. Knowing my dad, I think the first reason was why he kept doing it. He enjoyed the looks of disbelief he got. Even more so after he quickly verified the numbers.
I sure do miss him.
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16" woof.
Ivory? No, more likely celluloid over wood, older ones mahogany, newer ones bamboo.
Ivory rulers were common apparently in the early part of the 1900s.
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Nifty! I worked at San Jose RL in the 80s and also Yorktown with the Fellow who invented the permalloy readhead.
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I still carry a slide rule (Score:2)
It's on my Citizen Skyhawk:
https://www.youtube.com/watch?... [youtube.com]
Never had to use it but I can.
The elegant simplicity of slide rules (Score:4, Interesting)
What I find interesting is that it took a tremendously more advanced technology to render slide rules obsolete.
To make a slide rule, you need to figure out logarithms, then make exact marks on wood or something.
To make a modern calculator, you need to invent the microchip! You also need to invent a suitable display technology: light-emitting diodes or liquid crystal displays. We literally put a man on the moon before anyone was able to make a pocket calculator.
I love reading old science fiction stories set in the far future, where in the year 3423 or whatever people are still using slide rules. I imagine in the year 3423 people will still be using chairs, and probably spoons won't be too different... and back when those old stories were being written, slide rules seemed like that kind of basic item that wouldn't be going away.
P.S. Before the "pocket" calculator was invented, there were electronic desk calculators using Nixie tubes! Watch this video and think of how much labor it would be to assemble one of these. The soldering work alone guarantees that a typical college student could never afford one of these, but I'm sure NASA had calculators like this for engineers to use.
https://www.youtube.com/watch?v=mig3TeKh0aU [youtube.com]
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Nixie tubes. Meh.
How about an HP 9100 [youtube.com]? Programmable, scientific functions, RPN. And no integrated circuits (all discrete component logic).
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My guess is that it's a slide rule in postscript. Too bad Slashdot messed up the formatting.
Collection (Score:2)
In addition to one I carry (Pickett Model N 3-T) I have a decent collection, including some special purpose 'slide rules' or circular calculators. Like an Air Force MB-2A. And a couple of (now declassified) missile and nuclear weapons effects calculators.
Now that's a name I've not heard in a long time. (Score:4, Funny)
Slide rules are indeed a very old technology. In fact, the underlying principle goes all the way back to Noah.
After Noah got off the Ark, he sent the animals to go forth and multiply. And each month he went out to see how they were doing. As you might guess, after the first month or so there were baby rabbits, then baby cats and dogs soon after, and even a baby elephant after the first year. But month after month, Noah could find no baby snakes.
Finally it dawned on him that the snakes were cold blooded, and needed to sun themselves in order to get active. But the wet ground, and the lack of trees, had been perfect for bushes, weeds, and all kinds of plants, and the snakes were getting shaded out as it were. So Noah went back to the Ark, collected some timbers he'd used to strengthen the decks, and used them to build a table. And sure enough, the next month there were baby snakes! (scroll down...)
Which just shows to go, even an adder can multiply if you give him a log table.
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Three puns in one punchline - nicely done!
Miyazaki "The Wind Rises" animates a slide rule (Score:2)
Jesus Christ used a slide rule (Score:2)
Holy crap, I'm old and even I never used a slide rule. Calculators were just coming out when I was in 8th or 9th grade and by the time I had graduated High School they were everywhere. $40 or $50 would get you a pretty damn good calculator.
If not for my $15 Texas Instruments calculator (a mandatory purchase for tech school) I never would have made it through and neither would anyone else in my classes. Calculating Thevenin circuit values would have taken all day on a slide rule. We'd have spent most of our
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No, you're not old, you just think you are. I used a slide rule in high school and college, although electronic desktop calculators were just starting to come out. I didn't buy my first four-function calculator until I was in the Navy, back in '72; if memory serves, I got it in Hong Kong for almost $200 American, and it lasted for several decades.
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The way Apple supporters carry on, you would think that Jesus used an iPhone.
Anyhow, you are probably not that old or didn't do much math.
Specialty rules lasted beyond the early 70's (Score:2)
As has already been mentioned, when I took my Pilot's License the Cessena Student Kit included a Circular Rule, and was the standard tool used everywhere in Aviation. If you boarded an aircraft during the 1980's, you were depending on a type of Slide Rule to get wherever you were going safely; if you were flying a light aircraft you probably used one up until sometime in the last decade.
When I owned a retail store in an industry where discounts from MSRP were Standard Operating Procedure, we kept our Wholes
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I just started pilot training. I was given and was instructed how to use an E6B flight calculator. It's pretty nifty.
One of hte last (Score:2)
In 1971 I took the required freshman Engineering slide rule class. Not too difficult as I had been using my father's K+E Log-log Duplex Decatrig for many years and my father had taught me many tricks to squeeze out one more significant digit. (I still have it.) Not only was it dropped from requirements, but it was not even taught the next year. I still think it was a bad idea.
I also took tube design (valve to you Brits) and I still think that what I learned there was invaluable even though I never worked on
I had an office at Pickett building (Score:2)
Sci Fi quote about slide rules (Score:2)
As someone too young to have seen slide rules, I nonetheless loved this [wordsfromtomorrow.com] quote when I read it in Asimov's "I, Robot":
So they waited and relaxed until the drawing-board men and the slide-rule boys had said âoeOK!â
Despite the references to the nerd technology of the time, the intent of the sentence is so clear that it brought a smile to my face, thinking of the nerds that would have read that back when it was written and instantly feeling a sense of recognition.
Slide rules Ha! (Score:2)
Sure we had slide rules, I've still got three, but Us Real Geeks had an IBM 360 reference (green) card tucked behind our pocket protectors along with the assembly ref. Just for the cool factor you understand because we had them committed to our magical meat memories and analysed our core dumps easier than mortals could read a bus schedule.
Still have my high school plastic Pickett (Score:2)
Log Log for $1.50 with a pigskin cover. We suspected the pigs used werent that fresh.
Didnt see a calculator until I was a senior in college and their library got some desktop LED models.
Slide rules were never like cell phones... (Score:2)
I never used my slide rules in the fashion of a cell phone. However, my cell phone does have a calculator.
Also, I never wore mine off of my belt. The good ones were too long and too expensive to dangle and flail about. Most people I knew had a pocket one for convenience and a better, longer one for the real work.
Status symbol? Only to us geeks (Score:2)
Slide Rules were the first personal computers and a status symbol akin to what cellphones are today.
"Status symbol"? Maybe if you were in physics class with the other geeks. More of a scarlet letter to the rest of the population.
Don't get me wrong, I've used a slide rule (dad lent me his) and rocked it proudly but let's not pretend it was a status symbol outside of a very narrow group of people.
Still in use today in general aviation (Score:2)
While the "slip stick" is no longer used pretty much anywhere, any amateur pilot will be able to quickly demonstrate his E6-B Flight Computer. The proper use of this device is mandatory to obtain a pilot's license, and it's actually a pretty decent way to perform a lot of quick, yet otherwise-complex calculations for fuel burn, wind drift, en-route time, etc.
In commercial aviation, they've been replaced by flight-planning software and more sophisticated avionics and navigation systems, but they are still i
Fast Change from Analog to Digital (Score:2)
Shortly after taking that class the first Texas Instrument scientific calculator bec
Easy to Use ? (Score:2)
I remember those days with a sly drool (Score:2)
I still have my K&E log-log made of mahogany with a plastic vernier scale.
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Easy if you understand the equation. Any two values and all.
But with the slide rule, how did you decide to choose a particular pair of values? Choose one and find the other? Pretty much the same process.
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I've visited Cliff at his home and he had one of the giant teaching slide rules hanging up.
FWIW, here's a shot of some I own. They span from me back to my great grandfather:
https://www.flickr.com/photos/... [flickr.com]