The iPhone of Slide Rules - Numberphile

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Alex Bellos discusses slide rules and then the Halden Calculex, which he describes as the "iPhone of Slide Rules"
Alex Bellos: www.alexbellos.com
Slide Rule Museum: sliderulemuseum.com
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[@stevepaulsson8266]

Old joke: the definition of an engineer is someone who when asked what 2x2 is, whips out his slide-rule and says "3,9"

[@dochatteras]

+Steve Paulsson Yes. And yet, the Boeing 747 was designed solely using the slide rule. With training and practice (like all things) it's amazing how effective they could be.

[@SorakaOTP462]

+Steve Paulsson Not 3.9, more like 3.99998.

[@idlingdove]

+Steve Paulsson The joke I heard when I was young went as follows:Definition of an old-time engineer: ask him what 2x2 is, he whips out his slide rule from his back pocket, and says "about 4". Definition of a modern engineer: ask him what 2x2 is, he whips out his calculator from his shirt pocket, and says "4 point zero zero zero". I guess that a natural extension of this for the current generation would be: ask a current engineer what 2x2 is, he looks at you and says, "why don't you Google it?".

[@heimdall1973]

A mathematician will say there is exactly one solution. An accountant will ask what you want the answer to be. There are more but I don't remember them.

[@dontworry1302]

An Engineer will ask How close does it need to be?

[@TheHoaxHotel]

I carry one as a concealed weapon. Fast and functional, guaranteed to make an attacker's brain hurt.

[@m-yday]

You know what. That's a magnificent comment

[@jaakkohintsala2597]

+Shvet Maharaj i agree

[@rudyhero1995]

+Shvet Maharaj a significant moment*

[@888SpinR]

+The Hoax Hotel Shame on you, carrying around a weapon of maths instruction like that!

[@Bobdowntheroadshow]

+888SpinR "weapon of maths instruction" give this man a clap.

[@largesatsuma]

Price 1/6 = 1 shilling and 6 pence. Pre-decimal currency was used in the UK until 1971.

[@davidellis4031]

+Slim Charles Yup - you got there first my friend. I guess I can add that it's technically 7.5p in today's money, but that was from the time when the £500+ that an iPhone costs now would buy you a country mansion.

[@ranged12345]

+Slim Charles Which is around 13 pounds accounting for inflation.

[@mickthomas8983]

+Slim Charles How I learned to remember conversion from 'old money' into 'new' is to remove the slash, and then half the remaining figure. So, 1 / 6 becomes 16, half that is 8 (pence). Not exact, but near enough if you were in a shop in 1971. I love the way it works out in two easy steps. ** Potential joke about LSD (pounds, shilling, pence) producing a warm fuzzy feeling in the early 70s **

[@jesusthroughmary]

+Mick Thomas Actually works out to be 7.5 new pence.

[@mickthomas8983]

+jesusthroughmary Thank you. As I said in my comment, 8 pence was "Not exact, but near enough...". It's just the 'ready-reckoner' method to reach a close approximation. I also used an online converter and got 7.5 new pence.

[@LNC4P]

As a pilot, we use these circular calculators on a regular basis. However, more modern digital calculators are now becoming more prevalent. These aeronautical computers are called E6-B or CR-3 computers. You can also find them on wrist watches as their bezel. Probably the most common company that designs such watches is Citizen but I also have a Pulsar with such bezels. It does come in very handy when you need to do a somewhat complicated calculation on the fly.

[@howardebenstein3204]

On the fly, eh?

[@drenz1523]

nice pun

[@leonardomona9376]

7:14 "what do you do with that?" ," i sort of take it out and stroke it, and polish it and put it out it there.And you know, talk to it". LOL

[@jakebrodskype]

Most slipstick users know to use the C and D scales for multiplication and division. The A and B scales are squares of the C and D scales, so you lose some precision there.

[@ffggddss]

Yes, because the A&B scales have half the cycle-length. There was often also a K scale, for cubing the C&D scales. One-third the cycle-length, which meant even greater loss of precision. Fred

[@pyropulseIXXI]

I have LL1, A, B, ST, T, S, C, D, DI, k, LL2, DF, CF, Ln, L, CI, C, D, LL3, +e on my 5inch Pickett N600-ES LOG LOG Speed Rule

[@deezynar]

I hear him speaking quietly in the darkness, 'My preciousss!.'

[@simonmacomber7466]

I remember wandering around to many cities with my dad at some point in the mid 1980s while he desperately looked for a place that sold slide rules. The fact that few employees of any store knew what one was, kept making him angrier and angrier. But not as angry as he got when an older employee pointed out that they had stopped making such things because scientific calculators did the same thing much better. I had been using such a calculator in high school starting in 1984.

[@estebson]

Oh man, I imagine you've gone through the same feeling looking for something from your childhood in modern times or finding people not knowing what you're talking about, ha ha 😅.

[@silvereaglexi3888]

A nerd's lightsaber is a lightsaber.

[@cicci0salsicci0]

+SilverEagle XI fair enough

[@1rian25]

I think he meant it in comparison to a Jedi.

[@silvereaglexi3888]

Kneedragon1962 i would say the sonic screwdriver is in a separate category, and that you could say the same thing i said in my original comment except replace the word "lightsaber" with the words "sonic screwdriver" and it would still be true.

[@Kneedragon1962]

+SilverEagle XI Conceded.

[@havan56]

+SilverEagle XI yep. I'd say that this is the Steampunk Lightsaber

[@alancantor9437]

I was an engineering student In 1974, and I relied on a circular slide rule -- although mine was mass-produced and not nearly as elegant as yours! I may have been the only person in my class of who didn't use a straight slide rule. I thought the circular model was better because it was as accurate as a pi * diameter model, but took up less space. Maybe it even fit in my pocket! The price of electronic calculators dropped around that time, and within a few short months, all of my classmates and I abandoned our slide rules in favour of HP 35s, TI SR-50s, and so on.

[@paulpeterson4216]

I had several professors in the Chemistry and Physics Departments who could readily get three or four significant figures out of a slide rule. I had two, one standard model and a circular one, though the latter was a relatively cheap plastic one, not like this guy's. It did fit in your shirt pocket though, which was a plus.

[@JoeJoeTater]

Man, ya can't make a video about slide rules without throwing in an explanation of how logarithms make them work.

[@numberphile]

+JoeJoeTater it's been done so many times (as you allude to yourself) that I actually cut it out!

[@Skelpolu]

+Numberphile Okay, point taken - However, could you add an annotation to a video explaining how logarithms make them work?

[@Nilguiri]

+Numberphile Sounds ideal for a cheeky Lagniappe?

[@tomwhiteley4126]

+JoeJoeTater If you look at the first 2 laws of logs, which show that adding logs is the same as multiplying logs, and division is the same as subtraction, then it takes advantage of this fact, if you take a logarithmic scale :)

[@TheRipler]

+Numberphile This needs extras. Also would like to see more about the other scales.

[@Mrfailstandstil]

*I DEMAND a review of all of the collection of maths instruments that he has!*

[@dpnast8301]

I demand logarithms and trigonometrics on slide ruler

[@markprange238]

In the background he has a cylinder with a spiral logarithmic scale.

[@L17bligaman]

Totally Agreeable

[@Triantalex]

??

[@jjwarner9419]

But do I have to buy a new one every 3 months?

[@maxnullifidian]

And do you have to camp out in front of the store for 3 days before it's available?

[@RWBHere]

No. They will last a lifetime if cared for properly, and they never need re-installing or upgrading. Mine is over 40 years old and is as accurate as it was when new.

[@kemcolian2001]

@@RWBHere r/woosh

[@abhijitbhandarkar]

07:17 "I just kinda take it out and stroke it and talk to it" You sure you talking about the calculus mate ?

[@mr.champion7304]

no he's talking about the trigonometry.

[@holdenew]

"It's actually rather lovely, the way this moves in and out. It's so beautifully done; it's actually very pleasurable just doing it like this." - Alex Bellos, 2016

[@thewwefan57]

It's incredible how there is no limit to how useful and practical something can be

[@stocktonjoans]

"Mother, I have the knowing of the sliding rule! I can tell the sine what to do, and the cosine likewise and work out the tangent of t'quadratics" Terry Pratchett RIP

[@clockworkkirlia7475]

Yes! Haha, that's exactly what I was thinking of. I didn't realise how calculation-assisting the actual thing was... As ever, GNU Terry Pratchett

[@onthespoke2]

ᕮ ͡° ͟ل͜ ͡°ᕭ "It's actually rather lovely the way this moves in and out. It's so beautifully done. It's actually really pleasurable." ᕮ ͡° ͟ل͜ ͡°ᕭ

[@Gribbo9999]

1/6 "One and a tanner " . I've still got my British Thornton slide rule (c.1970) - the engineering student's weapon of choice. It was a liberation after using log and trig tables at school. The "the hairline" is actually called "the cursor" by the way.

[@mandolinic]

I recall when I was at school 40+ years ago, one of my maths teachers had a helical slide rule. IIRC, it was about the size of the inner core of a toilet roll, but apparently the scale was about 60" in length.

[@ffggddss]

Ah, back to the days when "cursor" meant that hairline thing on a slide rule!

[@CineMutt]

At college in the early 1960’s in the US, you could identify the math/engineering majors easily by the leather holsters on their belts for carrying their slide rules, and the white plastic pocket protectors with pens of different colors. They wore these proudly.

[@zuutlmna]

My college chemistry instructor used a round slide rule. He was extremely quick with using it, too. Kept it in his shirt pocket.

[@nerd9684]

I was born in 89, so I didn't get to use this. But I'm geeking out right now about this. Thank you for showing this amazing device.

[@RalphDratman]

I loved my slide rule! I taught myself how to use it when I was 13, and it was a great help to me, first in high school chemistry and later in college physics.

[@MurcuryEntertainment]

Man I love analogue computing devices. I have no idea how to use most of them, but they're incredible.

[@DaveScottAggie]

In the printing industry, we still use something, called a proportion wheel (sometimes we call it a reduction wheel). The inner wheel has the size of original, and the outer wheel ha the size of the reproduction (the output). There is a little window with a pointer which will tell you what percentage of enlargement or reduction is necessary to achieve that particular scaling. It is very fast to use. It essentially only does division and multiplication. For example, put original on 8.5 inches, and reproduction on 34 inches, then read out 400%. With it still set at the 400%, look at the 11, and see that the other side of an 8.5x11 sheet of paper will enlarge to 44 inches. That's a fairly simple example, but various tasks come in, almost every day.

[@dochatteras]

I have a Citizen aviator's watch with a circular slide rule built in. During WWII, they were commonly used by aviators to calculate distances, fuel consumption, etc. It is extremely convenient, and I often use it instead of whipping out a smart phone. Plus it looks beautiful!

[@halocemagnum8351]

more of this guy. I love how exciting he makes math!

[@shayan_ecksdee]

No we need more from four handed senpai

[@Blox117]

+Halo CE Magnum too bad bungie nerfed you in halo 2

[@halocemagnum8351]

Blox117 i know what a tragedy.

[@Blox117]

Halo CE Magnum RIP my favorite weapon :(

[@halocemagnum8351]

Blox117 hey you can use me on Halo CE pc, Halo mcc and im Coming soon to halo 5!!

[@dannywhittaker8219]

My dad just gave me his old circular slide rule for my birthday this year, pretty cool stuff!

[@Enkzan]

My grandfather had an identical slide ruler when he studied to become an engineer. When he passed a few years ago, as I started my education, I got it. It's complete with an old weathered leather case. Beautiful piece that I wish I'd been taught to use instead of calculators. :-) Lovely video!

[@richardwakelin843]

I grew up in the 60s, dad was an engineer & draughtsman and we was used to using old school things, i can remember the first readily available casio calculators and digital watches, we had a b&w tv which we had to tune with a dial & sometimes had to move the ariel about to get a reasonable signal. I forgot all about these things until i saw your sliderule. Thanks for the memories. Have a great day 😊

[@wallace4181]

As someone who used a slide-rule as a young engineer in the early 1970's, I can tell you that you could do a lot more with one than shown here. Also, the "hair-line" he mentioned was on what was known as the "cursor" (OED definition at that time "Transparent slide engraved with a hair-line and forming part of slide-rule). I still have my old slide-rule by the way.

[@MrTanker10a]

I still have my yellow PICKETT slide-rule from high school since 1974… I was taught to use the C (Top Scale) and the (D-Bottom Scale) for Multiplication, Division, Fractions and Ratio Calculations...

[@MaxTSanches]

From Canada (British Columbia) - I'm 63 and learnt how to use a slide rule in my grade 11 physics class. The next year the school had purchased one class (30 students) worth of electric calculators. So, we all had to learn Reverse Polish Notation to use them. The slide rule was easier, and the calculators could not leave the physics department room. So, we did our homework on the slide rule. I think that mine was the last class to learn how to use the slide rule. In the year 2000 I return to university to get an engineering degree and found that the slide rule was very useful as a log ruler, when you took out the centre slide. The other students would have to measure and then convert to logs to make a log / log graph. I could just measure with the centre slide directly. :) .

[@IdleGod]

When I was learning to fly, I found a circular slide rule on a cheap watch at a swap meet. The guy had no idea what it was, and thought the ring was some kind of timer. Picked it up for maybe $20. Despite being a huge tech nerd, the watch and slide rule made learning to navigate a lot easier. It's a far cry from GPS, but really useful if you don't have them.

[@AustrianAnarchy]

The Halden Calculex is quite the opposite of the iPhone. It continues to work with no way for its makers to "upgrade" it into complete uselessness.

[@HilbertXVI]

AustrianAnarchy Lol wot

[@JimProng]

And it doesn't cost £700.00. You also do not have to pay the manufacturer to add functions. Where it is the same is that if it breaks, its cheaper to buy a new one than to get the old one fixed.

[@aaronmicalowe]

And you never have to recharge it or uninstall broken apps.

[@jameswalker199]

I'd say it's accurate: someone else's innovation put in a pretty package and sold as new and unique.

[@RWBHere]

@@JimProng It probably cost the equivalent of today's £700 when new though. Maybe a couple of pounds each in 1905, which was at least a month's wages for a labourer. An iPhone costs around 3 weeks of pay for someone on minimum wages today.

[@PilchPlays]

You tease me with the iPhone of Slide Rules in the title only to show me the Bentley of slide rules. I was expecting to see an over priced and over hyped slide rule that had an option to be gold plated and was rendered obsolete after the first year it was introduced.

[@heimdall1973]

Similar thoughts. Remember also that you can't repair it...

[@tehPwnzor7306]

This video finally convinced me to go buy a slide rule (a beautiful Pickett N300-T, with plans to get an N515) after months of researching and looking at them longingly. Thanks, Alex :)

[@davidcole217]

I am one of those 60 + guys who used a slide rule in my Navy schools. The kicker is they were teaching me electronics for digital computers. I had two, one the Navy supplied and a better one my father bought me. It was a great tool. Very easy and fast.

[@Cythil]

I think the Halden Calculex is prettier then a iPhone.

[@888SpinR]

+Cythil To be fair, it *is* prettier than your average phone on the market.

[@Cythil]

888SpinR Yep. But to be fair a iPhone is about as pretty as most of it competitors.

[@fattyacid1901]

What we need is a calculex app

[@TheBluMeeny]

Its also more useful, and not snobbishly over priced. HEH

[@JohnSmith-do4fm]

+Cythil Check out the Soviet KL-1 pocket watch-style slide rule. Way sexier and postdates the Haldex by almost 60 years.

[@Dracopol]

There was an art to using slide-rules. If you had a formula with a lot of terms in the numerator and denominator you would often, rather than going straight through the numerator terms (multiplying by) and then straight through the denominator terms (dividing by), you would alternate, minimizing the times you would go beyond the scale and have to re-index the scale (replace the left "1" with the right "1" for 10, or vice-versa). The circular slide-rule removed this problem and allowed you to go in any order you wanted.

[@carmium]

My Dad worked in lumber sales, back in the day when little gifts with your company's name and number were popular things to give to clients and and buyer. One day, he asked if I wanted this circular slide rule he'd been given. It was a couple of years before we had to use them in Physics class, but once we did, it attracted some attention. It had the advantage of never having answer "off the scale," which can happen with the standard type. It took a little figuring, but I happily used it thru my latter years of high school.

[@klausstock8020]

So nice that you propose to me! I will, of course, accept the Calculex.

[@DancesWithRobots]

You would have had a (somewhat) easier time had you demonstrated multiplication with the C and D scales which were the ones intended for multiplication.

[@lovefrombooks7]

I want to get one of these for those tests my teachers tell me I can't use a calculator. I'll pull out my slide rule and be like "no problem"

[@ffggddss]

+lovefrombooks7 I don't think that'll fly! A slide rule IS a calculator - a mechanical analog calculator. OTOH, your teacher might be impressed that someone your age not only knows what that thing is for, but actually knows how to use it!

[@hugoflores5806]

@@ffggddss estra points for explaining it?

[@ffggddss]

@@hugoflores5806 Explain "mechanical analog calculator"? Well, it's *mechanical,* because it has parts that move, by hand - no battery required. As opposed to electronic, which has circuits and an electronic display. It's *analog,* because it has continuously movable scales, from which numbers are read out; as opposed to digital, which gives its results as multiple digits. And it's a *calculator,* because it can be used to calculate stuff. BTW, an abacus fits all these definitions, too. Fred

[@hugoflores5806]

@@ffggddss No, I was thinking about the log part, and the algorithms for solving different operations

[@ffggddss]

​@@hugoflores5806 You have two scales, C & D, each movable wrt the other. Each has numbers marked where their logarithms are - "1" is at position 0.000 = log1; "2" is at position 0.301 = log2; ... "10" is at position 1.000 = log10. - where position is fraction of the scale length (typically 10 in or 25 cm). So when you move the slide to place the 1 on the C scale over the 2 on the D scale, every number on the C scale is sitting on its own log plus log2, on the D scale. But that means that 4.7 on C sits on 4.7 * 2 = 9.4 on D, etc., so that each marked number on C sits over 2 x itself on D. And so it goes for any multiplier other than 2, that you move the slide to. Fred

[@Yupppi]

My cousin brought a similar disc from a vacation trip, but it was like a calender. You could find planet movements and all kinds of crazy details throughout the year from it. It was such a beautiful item, the base was like a stone puck.

[@robertgillcash1696]

I had a watch with a circular slide rule around the outside in approximately 1970. Used it on a few occasions in detention, they'd give you a pile of math problems to do, when you finished them, you could leave. For some reason, I was always finished way faster than anyone else!

[@Schindlabua]

> iPhone > Height of technology lol

[@enosunim]

+Schindlabua But it surely have some scientific calculators, for $95.95 in the appstore.

[@Mp57navy]

+minus1 I am certain, the Iphone won't have 100+ years battery life.

[@enosunim]

Mp57navy But it has much more accuracy, and who need 100 year battery anyway. Look, those devices from video are much yonger than 100 years, but already useless for anyone except those who speak with relics. )))

[@8ytan]

+Schindlabua I thought the iPhone comparison was more because it is much more elegant and portable than a normal slide rule, much like an iPhone is to a normal calculator. Both are also considerably more trendy than their counterparts.

[@BunnyArisu]

+Ben F That's exactly what he was going for in the video. This is just a shitpost of "hurr durr gota maek fun of da ifone lolool"

[@mikeg9093]

Why is he doing multiplication on the A/B scales? Typically the C/D scales are used for multiplication and division. A/B used for squares and sq rts. when compared to C/D. He could have gotten twice as accurate to the 15M answer by using the C/D scales because they are twice as long.

[@blue_blue-1]

There is an advantage: you don‘t get off scale.

[@zerobeat2020]

I still have my dad's round slide rule which is an "Improved Jeppesen Computer model CR" from 1960, which allows you to calculate a host of things related to aerial navigation, from flying times, speed, distance to fuel consumption, drift, density altitude, airspeed, mach number, as well as ordinary multiplication a division. My dad used this while working as navigator with KLM Royal Dutch Airlines, well before I was born. My dad is no longer with us, but his Jeppesen calculator keeps his memory well alive! He loved flying and particularly navigation. For a while after his retirement he marked navigation exams for the Royal Dutch Flight Academy, now known as the KLM Flight Academy.

[@TjPhysicist]

i really love the slide rule on my navitimer when i wear it. i don't always wear a watch but that slide rule is super useful for quick calculations and comparisons, esp those where's being off by 2 or 3% isn't really important (tips, comparing costs per unit volume etc)

[@canisfabico]

My Father is 83 years old and said he remember using this

[@rgfrw]

I'm 73 and still have mine. But I dont use it.

[@General12th]

How old are you? Doesn't matter -- use this whenever you want.

[@lawrencecalablaster568]

:D I have a slide rule & it is wonderful! I don't use it very much, but I do enjoy using it very much.

[@SlideRulePirate]

+Lawrence Calablaster I hear ya.

[@JohnSmith-do4fm]

+Lawrence Calablaster I collect these bad boys. They're so cool! I try to use them as often as I can to stay proficient with them.

[@heimdall1973]

When I went to school and worked out how the slide rule works for multiplication using log scales, I once designed a slide rule for powers using a log scale and a log log scale. Trouble is, such an instrument would not be of much use. Apart from calculators (which were not supposed to be used in schools), we used log tables and such, but never slide rules.

[@123pirke]

During my privat pilot license training we still learned to use a circular slide rule in the cockpit! Even now in 2016 it is still required :) It's called the E6B Flight Computer. It has a front and back side. The front side is a "regular" slide rule with many conversions (fuel, time, weight), altitude density, etc. The back side is used for wind angle corrections (steering angle to compensate for wind drift). Great stuff, but my tablet with GPS makes life a bit more easy ;)

[@liquidminds]

thanks, still got the one from my grandfather and now I know how to use it. a bit at least :-)

[@Kneedragon1962]

+liquidminds Learn how to use a conventional slipstick. Once you have that, going to the circular one is pretty easy - it's the same thing but without the ends.

[@General12th]

I mean, it's not like reading a slide rule is a lost art. They're not _that_ hard to figure out.

[@BrianRonald]

You're murdering the precision by using the A and B scales.

[@fjarandag]

+Brian Ronald Of course C+D scales would give more precision, but having to align 10 instead of 1, looking left and divide by 10 would confuse viewers even more.

[@happmacdonald]

+Javier Aranda But I thought that was the entire point of having a ROUND slide rule?! xD

[@willemkossen]

I love this. I have two old sliderules and learned how to use them because i wanted to find out. Its ingenious. I love that circular one! Great stuff!!!

[@AndrioCelos]

I used to have a watch with a slide rule on it, a circular one used by rotating a ring around the glass. It wasn't very precise at all, but I loved it.

[@saboo_tage]

It is kinda like an iphone, it doesn't have a headphone jack either

[@forkontaerialis5347]

If you ever needed to do fast, approximate, analogue calculations on the fly, and it was 1906 you could whisk this out.... Oh, brilliant. Fast, approximate, analogue calculations come up every other day, and almost never without time constraints. This seems perfect for all of my needs, where can I order one. XD

[@glarynth]

2:15 The cursor is also indicating 7 on the D scale, which gives you a way to perform this particular calculation without using the slide at all.

[@dave5194]

Oh my, that circular slide rule is just absolutely beautiful! I must have one.

[@SuicidialDolphin]

So this is the son of the abacus?

[@EHaraka]

+Cyberpunk Alchemist Abacus is a digital machine, this one is analog. So, hmm... not quite.

[@nicosmind3]

+Cyberpunk Alchemist I would think an abacus is superior. I can remember learning one in school, but i was surprised we didnt use them more often. They were an easy and quick way to do math. And we should have stuck with them long enough to get the basic principles stuck in our heads. After all its how the Japanese do speed math!

[@HarrisFalk]

+nicosmind3 The abacus is superior for addition and subtraction, for all other maths the slide rule is superior.

[@SamsUndertale]

+EHaraka An abacus is an analog machine....

[@lin4cba]

+EHaraka Er....how the heck is an Abacus a digital machine? (I mean the original one, of course)

[@Lwyte17]

Calculex is a beautiful creation.

[@DFX2KX]

I've only seen a slide rule once in person. My folks and I where at a yard sale. And Dad must've recognized what it was just from the box and pouch it was (because I didn't see any labeling on it at all). And he pulls this thing out, and hands it to me. Needless to say, I was stumped. I knew there was something with it that I was missing, but couldn't figure it out. So he took it and multiplied a few numbers to show how it worked, and I was fascinated. Not fascinated enough to pay ten bucks for it, but it was neat none the less. I found out later that they made nautical slide rules, as part of the gear you attach to a chart table. That would be kinda handy of your GPS gave up the ghost on a trip, I think.

[@Kneedragon1962]

A slightly larger version of this was a standard instrument for pilots and flight engineers and anybody doing aviation until well into the 1980s.

[@AustrianAnarchy]

+Kneedragon1962 The US Army used the E6B, even that was more useful than an iPhone.

[@Kneedragon1962]

+AustrianAnarchy LOL - I thought the E6B was a Prowler with a noisy ignition system...

[@GBD1082]

It still is - I took my ATPL exams in 2014 using the CRP-5. I've never heard it described as beautiful though.

[@dominicvilleneuve171]

+Kneedragon1962 Yup, I still use my wizzwheel everyday.

[@dominicvilleneuve171]

+Dominic Villeneuve Thouh of course it is different from the one in the video seeing as it is customized for aviation.

[@nicholasfazzolari3647]

Rad! I want a slide rule. Anyone manufacturing them these days? I understand we have floating point precision in digital calculators, but I must admit doing my calculations with a slide rule seems like it would be a lot more rewarding!

[@billl605]

Finding the proper decimal point place is a work in itself.

[@noormubeenparbhoo2158]

If you don't an actual one you can find them on some watches

[@johnchestnut5340]

They now have slide rule apps for your phone. Download and enjoy. Imagine using a handheld computer to simulate a slide rule.

[@full-timepog6844]

@@johnchestnut5340 very analogous to things in life.

[@peterbonucci9661]

Amazon has round ones available from Japan. That may be the only source of new mathematical ones.

[@ericfrancis7816]

I have my late father's Curta II hand calculator, which he bought in Austria after WWII. It's my greatest treasure.

[@alyoshakaramazov8469]

Over 60. I remember my first college chemistry class in 1972. The professor, George Pimentel, had an HP calculator, and that was the first I'd ever seen. He couldn't figure out how to use it the first day. He told us he paid over $400 for it. Everybody carried a slide rule. A year later, nobody carried a slide rule: we could get a Bowmar Brain, which sold for more than $200 in 1972, for $40.00 in 1973. I still used a slide rule in as late as 1976 because we worked out of doors and slide rules were easier to read in the bright sunlight. I used a Pickett circular slide rule then, but I don't know what happened to that one. Now I have an HP calculator program on my iPhone. I've still got my original slide rule from college around on my bookshelf. A Pickett, made in Santa Barbara, Calif. I think I paid $30.00 for it, and that was a huge investment at the time.

[@oundhakar]

You ought to have used the C and D scales, which are twice as long as the A and B scales.

[@chirhoiota885]

Forget Common Core. Kids just need to learn slide rules again.

[@pmbrig]

In our high school physics class in the late 1960s everyone had to use slide rules. I was the only one who had a circular slide rule instead of a linear one. It was about 10" in diameter (so, not something to slip into a pocket) and had two transparent arms each with a radial hairline, one longer than the other, with the short arm designed to move with the long arm when that was rotated. The primary logarithmic scale around the rim had an effective length of over 30", allowing much better accuracy, and I never had to worry about "running off the scale" when, eg, multiplying 3*4. In addition, it had multiple other scales, including trigonometric scales and a log-log scale (allowing for exponential calculations). I found it much easier to use than the linear ones, and I loved it. It was very finely designed. Sadly, I ditched it at some point after I hadn't needed a slide rule for several years. I wish I still had it.

[@HarryWHill-GA]

My father taught me to use a slide rule as a boy. I have his circular slide rule from Civil Engineering University around here somewhere. A useful thing when what would be a free app today was selling for $800+ when I started at University. That was most of a semester's tuition.

[@Forrestman69]

Pilots around the world still use circular slide rules everyday in the forms of E6-Bs and CR-3s.

[@petar_donchev]

My father was a pilot / navigator until the 80s and he had exactly the same ruler plus a large rectangular one with circular part. Besides that all routes manually calculated and laid out on drawing paper. Flying used to take considerable math skills.

[@ParadoxBassCube]

One perfect tool to rule them all.

[@AngelTiel]

Perfect. The first video I've found which is accessible to young adults in a non-cringey way. Thank-you.

[@CreationSGame01]

You can hear the passion in his voice.

[@enough_b]

"It's actually rather lovely, the way this moves in and out, it's so beautifully done, this instrument, it's actually really pleasurable just going like this..." Had to.

[@scowell]

Wonderful video... have you done one on the Curta yet?

[@tylerljohnson]

+1 for the curta, I was thinking the same. it would be interesting to have a curta-like machine that could do trigonometric calculations.

[@tylerljohnson]

looks like numberphile did do a video of the curta, the same guy has one as well.

[@00Skyfox]

I use the E6B circular slide rule flight calculator in aviation. Same principle, and works really quite elegantly.

[@SteveBakerIsHere]

I love my Calculex - and it also sits on the "antiquated tech" display shelf in my office and is sometimes taken down, gently polished and then used to calculate pi times e. I'm jealous that you have the original box...mine only has the steel jewel box plus instruction book. Mine didn't work when I bought it - so I had to dismantle it to clean it. Unfortunately, when you do that - the back and front sides can become misaligned and you have to do some calculations that involve flipping it over in order to deduce the error you've introduced and recalibrate it before reassembly. But it was definitely worth the effort because now it moves smoothly. Somehow, the idea that this thing was to be worn like a pocketwatch in a gentleman engiineer's waistcoat is comforting! I turn to page 31 of the book - where I'm informed as to how to calculate the Indicated Horsepower and the Expansion rate of steam and the Area if the Steam port...and can just imagine some Great Western railway locomotive designer using my Calculex. I think my Calculex must be older than yours because my instruction book doesn't say "REVISED" - so now I have to worry about what errors got fixed in the revision!

[@kevinfontanari]

That thing is not like an iPhone, that thing is useful...

[@theechelonofmars]

Bwahahahahahahaha

[@marvelous1358]

hahahahaha.!!!!!! I LOVE YOU MAN

[@kevinfontanari]

I use a glorious Nexus 5, man! :D

[@sonny19931]

+Kevin Fontanari you know smartphones can do calculus, right?

[@kevinfontanari]

+sonny19931 Read above... -.-

[@inferno7181]

The iphone of slide rules? That really isn't praise for it.

[@General12th]

Should he have said the Galaxy of slide rules? If you don't think the modern phone is sleek and elegant, we have some strong differences in definitions.

[@sebastianjost]

Even if current I iphones aren't that advanced anymore compared to their competitors (they're mostly just overpriced), these saying refer to the first iphone, which was revolutionary at the time.

[@alphabasic1759]

Complete love this. I have a small collection of slide rules and I love them.

[@dannygjk]

Those types of instruments were also used in submarines to do angle solving for aiming torpedoes, (at least those subs that didn't have sophisticated TDC's).

[@ericstoverink6579]

iPhone of slide rules. So you mean that it's overpriced even though it does the same things as other less expensive slide rules, and the people who buy them only do so for the brand name?

[@jimharmon9917]

Pretty much, yes.

[@jpdemer55]

And an Aston-Martin V-12 Vantage takes you to the drugstore, same as a Honda Civic. There's a bit more to it than four wheels and a motor.

[@alan2here]

Can use super-log, the inverse of hyper-operation 4, to do powers?

[@NotAUtubeCeleb]

+Alan Tennant nothing uses tetration

[@alan2here]

+HybridNeos It would be useful if it works like this, because powers are a more common operation and thats the one you'd end up with finding. X^Y

[@alan2here]

+Alan Tennant Powers are more common than titration I mean, and much harder to do mentally than multiplication.

[@JohnSmith-do4fm]

+Alan Tennant Most slide rules log-log scales for powers.

[@alan2here]

It does works for powers too? :¬o Impressive.

[@ricardo.mazeto]

Brady, you and these guys made me love math. Thanks.

[@mikebauer9948]

(follow-up to below) of course there was some horsing around with them as swords, we used to wear them in scabbards on belt loops. Typically, scales A and B were for square and square root calcs, scales C and D were primary for mult and div, as they were full-length and thus more precise. Typically also, in school settings, math classes required fully reduced answers, such as "3pi/2" rather than the slide rule numerical approx answer, although you'd use the SR to check and gain practice useful for science classes. In the sixties and early seventies, professional offices were already transitioning to desktop electronic calculators before pocket calcs killed off the SRs entirely for most uses.

[@911gpd]

This thing rules... sorry...

[@leslievaughn1047]

911gp used to.....

[@0o32]

I have just bought one

[@meridianherschel1618]

I love videos like this. More math related collectible items!

[@firstnamelastname7143]

Slide rules and varieties are fascinating instruments, especially since the incredible mathematics were discovered so long ago. Always wondering how the principle was thought of, and tables calculated to so many decimals with such precision. Then picked up an old book years ago on designing and constructing 'nomograms' and the variations of function, and complex math, even more amazing than slide rules. From simple straight line graphs, to complex curves and geometry, to solve complex equations with a simple straight line through various points.

[@MazeFrame]

Can someone make a leather-jacket with "Slide rule owners group" stiched on the back?

[@ElectroNeutrino]

Would it be abelian or non-abelian?

[@cutecommie]

smartmusicfreak Asking the real questions.

[@pauloconnor2980]

You'd get beaten to death if you wore one of those in Frankston!!!!

[@jeffreyjefferson6047]

How can you possibly compare a beautiful, innovitave, elegantly designed, sleak, high class, easy to use, hardy, strong device to an iPhone? Blasphemy!

[@General12th]

To be perfectly honest, iPhones (and in fact any smartphone) is beautiful, innovative, elegant, sleek, and so on. They are perfectly smooth ingots of glass and metal.

[@SexyStarfleet]

LagiNaLangAko23 It’s funny because iPhones are supported in software far longer than any other smartphone. But you’re right, hur dur iPhone bad apple bad

[@HiwasseeRiver]

I'm old (50+) and I still keep one handy - always works when the power goes out, never needs charging and it confounds the young hipsters.

[@howardebenstein3204]

The power of logarithms never goes out. :)

[@Christopher_Gibbons]

I have a beautiful Russian artillery calculator from world war 1. It is a pocket watch design like this. I used it all throughout high school. Yes, there were great graphic calculators, but sliderules don't need batteries or maintenance. Once you set up a calculation you can do it over and over for any new value you want, so for problems with many repetitive calculations it can actually be faster.

[@spicytaco2400]

I learned how to use a slide rule and i'm only 17.

[@NetAndyCz]

Well, it is not that hard to operate...