posted by
Fnord666
on Tuesday April 26 2022, @11:57AM
from the three-significant-digits-is-all-anyone-would-ever-need dept.
from the three-significant-digits-is-all-anyone-would-ever-need dept.
https://sliderulemuseum.com/SR_Course.htm
This self-guided course gives numeric examples of the basic calculations that a slide rule can do. Just follow the step-by-step instructions and you will be amazed by the power and versatility of the venerable Slipstick. Click on any of the images below to get a large, unmarked, blowup of each slide rule as shown in the problem.
This discussion has been archived.
No new comments can be posted.
llustrated Self-Guided Course On How To Use The Slide Rule
|
Log In/Create an Account
| Top
| 40 comments
| Search Discussion
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
(1)
(1)
(Score: 3, Interesting) by bzipitidoo on Tuesday April 26 2022, @01:00PM
My father had some slide rules stuffed away in a drawer on his drafting table he picked up for free when his employer was giving them away to make room for computers. Just one time, he put on a very short performance in which he did just one calculation, to show me how to use a slide rule and that he could work one.
He wasn't eager to keep using slide rules. He had embraced the pocket calculator. Bought a Heathkit calculator that had to be assembled. That wasn't pocket sized, it was the size of a hardback book, with a full sized numeric keypad like those on 101 key keyboards, and not the quiet ones either. Complained that by the time he'd finished all the soldering and got it working, it was obsolete. It only did basic arithmetic anyway, so it couldn't replace the slide rule and the little book of tables of trig and log calculations. He'd already moved on to a calculator that was pocket sized, almost. Think it was a TI SR-50. It was a little too thick to fit into a shirt pocket, but it did finally make the tables and slide rules totally obsolete.
(Score: 3, Funny) by Anonymous Coward on Tuesday April 26 2022, @01:18PM (1 child)
When scientific calculators became available, my father had his slide rule mounted to a plaque (as one would do with a fish). It hung in his office until he retired.
(Score: 4, Insightful) by DeathMonkey on Tuesday April 26 2022, @07:03PM
That's really cool actually! If you don't already prize that as a family heirloom you definitely should!
(Score: 0) by Anonymous Coward on Tuesday April 26 2022, @01:37PM (17 children)
Even though I am middle aged, slide rules were obsolete when I was in diapers.
A few years ago, I played around a little bit with them out of curiosity. Slide rules are a major pain in the ass. What kills me the most about them is that they have very little accuracy: two significant figures, three at the most with a special slide rule. And they do not do addition or subtraction! Now that I know that, I see why adding machines existed at the same time as the slide rule. Slide rules are completely worthless for business calculations.
(Score: 4, Informative) by janrinok on Tuesday April 26 2022, @02:09PM
(Score: 2) by HammeredGlass on Tuesday April 26 2022, @02:36PM (3 children)
NASA puts things within inches of their target using only two decimal places.
(Score: 0) by Anonymous Coward on Tuesday April 26 2022, @05:35PM (1 child)
I would prefer my bank balance computed to better than two significant digit accuracy.
(Score: 0) by Anonymous Coward on Saturday April 30 2022, @08:46AM
So would I. Guess it is a good thing those aren't the same thing. Or that you don't have to have the same number of significant digits in all measuring systems.
(Score: 0) by Anonymous Coward on Tuesday April 26 2022, @05:41PM
NASA used an army of operators on adding machines too. If you think the calculations were all done on a slide rule, you are bonkers.
(Score: 2) by maxwell demon on Tuesday April 26 2022, @03:00PM
That reminds me of a joke I've once seen long ago, that told how different professions answered the question "what is 2+2?"
The engineer's answer (which also showed that the joke was really old, even back then when I saw it — and of course ignored that slide rules don't provide sums anyway): "According to my slide rule it's a bit more than 3.9, and the last digit must be a 4, thus it's 3.94!"
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2, Insightful) by Anonymous Coward on Tuesday April 26 2022, @03:02PM (8 children)
I doubt that anyone ever suggested using slide rules for "business calculations". You would be much better off with an abacus.
True, but they were faster and easier than any other solution available at the time. Plus, people who used slide rules knew that the precision was limited and worked accordingly. I'll bet many people using computers today don't bother even thinking about the precision of the answers the computer spits out. Sometimes that can bite you in the ass.
(Score: -1, Troll) by Anonymous Coward on Tuesday April 26 2022, @05:39PM (7 children)
My point was that slide rules were not a GENERAL PURPOSE calculating device. They had huge omissions in their functionality and huge limitations on the functionality they did have. A $5 calculator blows them out of the water. Slide rules were nothing more than supplemental aids to hand calculation.
And an abacus? Please. Try adding machine.
(Score: 1, Informative) by Anonymous Coward on Tuesday April 26 2022, @07:17PM (3 children)
How did one calculate trig functions before getting a hand calculator, or fractional root powers? A slide rule is far superior for that purpose than looking up trig values or log tables in a book.
(Score: 0) by Anonymous Coward on Wednesday April 27 2022, @03:26AM (2 children)
It's not superior to tables if you want any precision.
(Score: 1) by pTamok on Wednesday April 27 2022, @07:51AM (1 child)
True, but tables and slide-rules are complementary. To get a quick feel for a result, slide-rules work well. And a slide-rule's precision (2 to 3 significant figures) in the hands of a skilled operator could be good enough. If you need more precision ( 3 or more significant figures ), then you use tables.
It was possible to get longer slide rules. Shirt pocket length ( about 6 inches, with a nominal scale-length of 5 inches ) and briefcase length ( about 12 inches with a nominal scale length of 10 inches ) were normal, but teaching models for use in lecture theatres could be considerably longer, and a cylindrical slide-rule with helical scales [wikipedia.org] was manufactured commercially for many years with a scale-length of 500 inches, giving 4 to 5 significant figures.
Easily available tables of many mathematical functions were generally 5 significant figures - See Abramowitz & Stegun [bham.ac.uk]
But tables of logarithms in that book are to 10 decimal places, "Compiled from A. J. Thompson, Standard table of logarithms to 20 decimal places, Tracts for Computers, No. 22. Cambridge Univ. Press, Cambridge England, 1952" (Review [cambridge.org]).
10 decimal places is better than my calculator (which gives me 9), and 20 far in excess of my calculator.
(Score: 0) by Anonymous Coward on Wednesday April 27 2022, @06:51PM
In 10th grade math we had a week of learning and practicing to use log tables (early 1980s). I would guess they stopped that part of the curriculum not too long after that. Simple hand calculators were pretty common by that point (using them to spell "boob" and "shell oil"), and by the end of the 80s we all had our HPs and other calculators.
(Score: 2, Informative) by pTamok on Tuesday April 26 2022, @08:11PM (1 child)
A $5 calculator is lousy for adding up a column of figures. All it takes is one miss-key and your total is wrong*, and you have no way of knowing.
A pencil and printed-out column allows high speed (no data entry), you can write sub-totals, and you can add checks in.
*Printing calculators/adding machines cost more than $5. The benefit of such devices is that you can compare the print-out with the original column of figures and quickly spot discrepancies. Before such devices, you would get two people to add up the same column of figures in opposite directions and compare results. By doing it in opposite directions, you reduced the chances of them making the same mistake, such as summing 71 and 39 to 100.
(Score: 1, Funny) by Anonymous Coward on Wednesday April 27 2022, @03:29AM
$5 calculators are fast. You could do the sum twice in no time at all to double check your work far faster and more accurately than with pencil and paper.
(Score: 2) by owl on Wednesday April 27 2022, @03:46PM
Let's try this differently:
My point was that $5 calculators were not a GENERAL PURPOSE calculating device. They had huge omissions in their functionality and huge limitations on the functionality they did have. A $139 computer [1] blows them out of the water. $5 calculators were nothing more than supplemental aids to hand calculation.
Note how your comment applies equally well to the $5 calculator, when comparing it to a full on computer.
When one's alternative was doing the computation by hand on paper, slide rules "blew paper out of the water". That was their benefit -- they were way faster than doing the math by hand, and precise enough for most uses, and when you needed the extra precision, they could serve as a good cross check that your paper long hand computed, precise, figure was also accurate.
[1] Basic android phone running Maxima (https://f-droid.org/en/packages/jp.yhonda/)
(Score: 4, Informative) by VLM on Wednesday April 27 2022, @11:51AM (1 child)
They're before my time but I bought a Pickett N-16-ES that's the EE slide rule at a hamfest long ago when they were going for about scrap value (made of aluminum, I think). I'm looking at it right now. It seems rather unlikely you'd run less than three sig figs although the last digit might be a bit fuzzy.
I've never gone thru the numerous PDFs online to figure out all the EE stuff but it.
The interesting thing about EE stuff is everything you own is made with (mostly) 5% to 20% resistors. The thing is they're manufactured over a more than million-to-one range of values.
Most of the world was built to about 2 sig figs.
Most of the "many decimal places" work involved addition and subtraction anyway. Honing an engine cylinder by hand to perfect size and shape and the micrometer measures 1.3489 inches and you want 1.3475 how long do you keep honing? Well that might be awhile but slide rules don't add/subtract anyway.
There is a false sense of precision when you tell a framing carpenter that according to your pocket calculator he should in theory be cutting those rafters to 141.421356237 inches long and he's like bleep you and whips out a tape measure and chops to the nearest eighth and that works fine because wood expands and contracts more over a reasonable climate range than that level of precision anyway.
Slide rules can only do 99.99% of the worlds work accurately enough. For the remainder there's paper and pencil.
A lot of engineering work is F around and find out, much like programming is mostly about typing in code that won't work and will eventually be deleted. So its 1950 and you're assigned to a classified X-band radar project and you've never done anything above 28.2 MHz and how should I design a matching network between the final amplifier and the antenna. Well, we always used discrete part LC circuits so we'll hit the slide rule at 11 GHz and see what we get. OK the slide rule says we need a roughly 0.2 femtofarad matching capacitor, and the Digikey COTS electronic parts catalog doesn't sell leaded ceramic 1950s capacitors below 2.7 pF because two component leads without a component at the top are probably about that many pF if the leads are a couple inches long, so we'll try a microstripline design (did that exist in 1950?) or do weird waveguide matching using frankenstein plumbing. Once you get a design close enough you'll whip out the paper and pencil and emulate LTSpice by hand, but you need to find a design thats close enough to start with and that's slide rule time.
(Score: 2) by owl on Wednesday April 27 2022, @06:12PM
Current ebay 'ask' value for that model is $125-$180, so they seem to be fetching well above their scrap value now from collectors.
(Score: 2) by looorg on Tuesday April 26 2022, @03:49PM (3 children)
I always found it somewhat fascinating to view someone that actually knew how to use one, and was good at it. They were quite fast with them. But it's like watching people do math in their head and know what they are doing instead of just asking the magic calculator. It's always interesting to watch someone that know what they are doing do that and do it well.
But for me personally it was just one of those things that fell by the side of technology. I'm not old enough that this was a thing anymore. I do have one or two in boxes but for me they are basically fancy rulers if I would ever need one. I'm not really sure where I got them from. Some relative probably.
(Score: 0) by Anonymous Coward on Tuesday April 26 2022, @05:45PM (2 children)
If you don't want them, consider selling them. They have become quite collectible. (See slide rule websites). It's just taking space in your house and depriving a slide rule aficionado of his joy. ;-)
(Score: 2) by kazzie on Tuesday April 26 2022, @08:38PM (1 child)
I have a box of them (20 or so, various types), and I use them once a year or so when teaching a class about logarithms. The topic is a poor relation to other areas of engineering mathematics these days, and doesn't get the love it deserves, so I like to give my class a physical representation of how adding logs is equivalent to multiplying.
(Score: 1, Insightful) by Anonymous Coward on Tuesday April 26 2022, @09:44PM
This, I think, was the greatest benefit of slide rules. It connected you to numbers and means of operating on them in a way that using a calculator simply can't do.
(Score: 3, Touché) by Anonymous Coward on Tuesday April 26 2022, @03:50PM (8 children)
As one who actually did use a slide-rule in college - and routinely did so with three digit accuracy - I gotta say all the comments full of disdain for this convenient computing device are evidence of unwarranted 21st century snobbery. If your current methods of computing are _so_ much better, how is it that you are unable to visit the moon again? Get a life people.
Kids these days!
(Score: 2, Insightful) by pTamok on Tuesday April 26 2022, @05:18PM
Slide rules don't need batteries (to be fair, solar powered calculators don't either). I do have an old Sharp calculator where the contrast on the LCD display has become very low, even with fresh batteries. A bit like the ink fading (or being rubbed off) on a well-used slide rule.
Use of them also tends to require a 'feel' for numbers in a way that calculators don't. Understanding precision and accuracy, making estimates to do a quick check that you are getting the answer you might expect, and understanding how to preserve accuracy in calculations. You can do the same using calculators, but most don't bother, relying on the answers to be correct.
Feel for numbers and mental arithmetic are skills that can be useful, but most people don't care. I can add up a column of figures (on paper) faster, and more accurately than many people less than half my age can with their smart-phones, and I don't regard myself as particularly skilled.
My mother worked a manual cash-register in a busy lunch-restaurant for a while. She would add up the total of what a customer had on their tray, and have change ready for the most likely note offered before they had got to the register and reached for their money. She kept the line moving quickly!
Before electronics, the good supermarket cashiers would know the prices of all the stock items: they would ring them up without needing to look for the price labels, which was impressive*. I'm not going to say that people should still practice those abilities, but having respect for the skills would be good. Other things are more important now, such as being able to navigate social media and smartphone apps. Humans are flexible - its part of what makes us human.
*Memorising 'stuff' is a trainable skill. Before printing, much literature was transmitted orally, and reciting the Koran from memory is still a quotidian feat for many.
(Score: 2, Interesting) by Anonymous Coward on Tuesday April 26 2022, @05:25PM
Seconded, used one in college, but quickly jumped to calculators after that.
Several years ago, I helped a friend who was writing an engineering biography. The engineer's family supplied scans of a sketch/notebook from the 1930s, full of various mechanical calculations. My contribution was to decipher the simple sketches and check the calculations. That guy was good, I only found one error (off by 10) while checking hundreds of different calculations.
Off by 10 is a common slide rule mistake, forgetting which end the slide is sticking out.
(Score: 2) by Freeman on Tuesday April 26 2022, @06:31PM
You can blame a fickle nation, Presidents, and sheer cost of going to the Moon. We went to the Moon, because we wanted to be first to the Moon. We lost out on a lot of Space firsts to the USSR and didn't want to be playing second fiddle. We also lost our competition and focus. Instead, NASA turned into a nice giant pork barrel. Thankfully, SpaceX partook from said pork barrel as well and is what a lot of people hoped to see from NASA. A forward looking US based Space company. Elon Musk may be nuts, but he can get things done. It helps that he has a futuristic bent as far as Space is concerned. Without that, there's not much of a point to pushing the envelope. May as well be another Lockheed or Boeing at that point.
Joshua 1:9 "Be strong and of a good courage; be not afraid, neither be thou dismayed: for the Lord thy God is with thee"
(Score: 2) by owl on Wednesday April 27 2022, @01:39PM (4 children)
I wonder if the 'disdain' is the result of those expressing the disdain only ever having used an electronic calculator (of whatever form) and therefore having no memory of "the days before calculators" where your choices for working out some math were pencil, paper and longhand or slide-rule.
Today in 2022 it is all too easy to look at a slide rule with disdain when calculators have become "just another app on one's smartphone". And few who did not live through the era will ever be able to properly imagine how it was to need to multiply some numbers, or do some Trig, but to also not have a calculator available to do so (since they did not exist).
Full disclosure, I fall into the category of "never had used a slide-rule" myself, having grown up just as electronic calculators hit the scene. But, I do also remember all the longhand multiplication and division problems I had to work out manually for math classes in grade school, without a calculator, and can imagine what a time saver a slide-rule was, back in the day when there were no "electronic calculators". I, for one, certainly brought a calculator to school with me just as soon as my math and science classes no longer banned calculators (I think I started bringing it in for the science classes, as they allowed them sooner than the math classes did). So I can also imagine, had I been going through grade school about ten years earlier, that I'd have done the same then, only with a slide-rule instead of Dad's second-hand (to me) old Radio Shack scientific that looked like a small brick, ate through four AA batteries fairly quickly if left on for any length of time, and had that blue glowing florescent screen that predated LCD screens on calculators.
(Score: 0) by Anonymous Coward on Wednesday April 27 2022, @05:27PM (3 children)
The people you see saying that slide rules were limited and a pain in the ass are the ones giving you an honest assessment uncolored by nostalgia. I appreciate the slide rule as an important piece of history and admire the aesthetics of the precisely printed scales and the construction of a smooth sliding slide rule. However, I do not use one when I have FAR better tools than that available to me. None of the slide rule promoters in this forum use slide rules either. They are simply obsolete.
(Score: 2) by owl on Wednesday April 27 2022, @06:38PM (2 children)
I'm certainly not recommending a "return to slide rules" for general math computations. Certainly not when, as you say, there are far better alternatives available today. And so far in reading the other comments, I have not gotten the impression that anyone is overtly recommending that everyone return to slide rules for daily math computation usage. Some have pointed out that the use of one gave one an intrinsic 'feel' for the numbers that is just not available from calculators or Mathematica, but even that I don't interpret as a "everyone should go back to using them" suggestion like it appears some of the "disdain" postings appear to have interpreted the comments.
I submitted TFA to Soylent because I thought it might generate some nostalgia and discussion, not as a suggestion to "go back to using slide rules". And it has generated some nostalgia and discussion. I don't get why a few posters seem to be interpreting it as a direct "you should all start using this for your multiplication and trigonometry work, instead of your HP/TI/Casio calculators" suggestion.
As I said in another post, I came through grade school about 10 years after the slide rule to calculator transition, and the only slide rule I remember from the time was the room sized one that was still hanging above the blackboard in the room where my HS Physics classes were taught. Of course, the teacher never touched the "room sized" slide rule for the entire class, so it was just a "wall decoration" at that time.
(Score: 0) by Anonymous Coward on Wednesday April 27 2022, @07:59PM (1 child)
You and I seem to be of the same era, but I'm a different AC to which you are talking. To this day I still feel pretty strongly in keeping calculators out of schools at least until high school. That "feel for numbers" is built up by experience, not punching numbers into a calculator or computer. Once one has learned the basics, then you use tools to make your life easier so that you can move on to learning other things. But not too many people seem to share that sentiment, so this is my own "man yelling at clouds" issue.
If you appreciate slide rules, you would certainly appreciate nomograms [wikipedia.org]. There is (was?) a wonderful python program to make your own, called pynomo [pynomo.org]. I used to use it to make nomograms for work where I had to make the same calculation over and over involving trig functions and square roots (and not sitting in front of my computer), and it was WAY easier to make a nomogram of my equation and use the straight edge of my notepad to do the calculation than it was to punch it into a calculator. That flight calculator mentioned in another thread is just a fancy nomogram. Again, the precision was only two or three decimal places, but it was exactly what I needed. I also have always loved nomograms as artistic expression, so that was another thing that appealed to me about it.
And if you aren't familiar with Cliff Stoll, you might enjoy his electric slide rule [youtube.com] for the modern age. :)
(Score: 2) by owl on Wednesday April 27 2022, @08:40PM
HS grad was '85, college was '90
Agreed. That 'feel' just does not get ingrained by punching the keys, at least not in the same way as having to go through the manual pencil and paper calculations. In a way it is similar to the Slackware vs. Ubuntu quip that goes around the internet that goes something like this: "Use Ubuntu and you learn Ubuntu, but use Slackware and you learn Unix".
Yes, indeed, thanks for the reference, I had not yet encountered those. Looking down the wikipedia page, the example for parallel resistance calculations nomogram immediately caught my eye (EE here). I can see a lot of uses for that chart in picking out "what can I get with these parts I have" or in the reverse answering "I need X, what two standard values come close enough".
Answering either, with a calculator, is a bit of a PIA (other than for the pairings one has memorized). Answering either with a chart like this would be way less effort than with any calculator.
(Score: 0) by Anonymous Coward on Tuesday April 26 2022, @05:17PM (5 children)
Every pilot has probably used an E6B at some point.
https://en.wikipedia.org/wiki/E6B [wikipedia.org]
I also used a more 'modern' variant that was entirely circular.
(Score: 0) by Anonymous Coward on Tuesday April 26 2022, @05:25PM (3 children)
What do you do in the middle of a flight when your calculator batteries die?
Reach for your E6B!
(Score: 0) by Anonymous Coward on Tuesday April 26 2022, @05:47PM (2 children)
Please tell me how many people ever used that thing in real life.
(Score: 0) by Anonymous Coward on Tuesday April 26 2022, @09:51PM (1 child)
I guess it depends what you mean by "in real life". I know how to use one and I have taught other student pilots how to use one as part of their training. Like a slide rule, it imparts a greater understanding of the underlying calculations going on, rather than just plugging numbers into a device and getting an answer.
I have not used one while actually flying however.
(Score: 0) by Anonymous Coward on Wednesday April 27 2022, @03:21AM
I suspect some of the most likely users would be long-distance glider pilots.
(Score: 1, Informative) by Anonymous Coward on Wednesday April 27 2022, @12:01AM
At battle stations on a sub, just about every officer in the control room wore one on a string around their neck. They are very fast for time/speed/distance/basic trig problems. And, you don't need 2 decimal points of accuracy to shoot a torpedo.