Frederick Post was the official and only authorised US importer of the Japanese "Sun Hemmi" slide rules, so much so, Hemmi made exclusive models just for Post, like the Versalog. I love mine. Even if I was born just after the slide rules went extinct, I still find them interesting and superior, from a pedagogical standpoint, to calculators and computers because they force the user to keep track of the significant digits, rather than believe arbitrary precision can be achieved all the time every time.

Nice set. Thanks for showing these. I am the half-generation behind you, in that I was a rare case in uni still using a sliderule, but haven't used one since second semester fields. The pocket carry was a 6 inch K&E, but my preferred were a circular rule (80mm diameter, for a scale length of 250mm, about 10 inches) on a rectanguler card that were a give-aways at trade shows. They may have been Concise (Japan), but are unbranded. I grabbed a bunch- GE jet engines division, GTE, Sylvania lighting, Philips, RCA, and a bunch of others I can't recall. All plastic, all had an embossed formula card in the middle. All came from the same factory, I would guess. I still have one or two around, and a bunch of the formula cards, as all were custom on one side. The GE came in real handy for thermo exams. A couple of the insert cards from the circular units still live in the cases of my HP voyager fleet, as they fit well. I culled the sliderule collection over the last 10 years or so (now maybe 20 or so, plus a file cabinet full of cardboard application-specific rules- impedance network parameter calculator, tube calculator, concrete calculations, radiograph exposure calculator, flight computers, and so on). I will never art with the 1m Pickett classroom model, though.

I was just using my Otis King a few minutes ago, and decided to revisit your video. I found my ancient book of log tables a while ago, and I've checked the accuracy of the Otis King log scale against Frank Castle's book. Spot on to a mantissa of three significant figures when the indexes are accurately aligned. It's easier to read off than on my large Thornton AD050. Amazing, and it's usably a pocket device, despite its apparent solidity and weight. No wonder I have it at work quite often.

Sold several Teledyne post slide rules at a rummage sale in the 1990s now have a iPhone super computer fits in my hands. We came a long way in 40 years.

I saw you measuring across the Fowler, and saying "in England, where they use centimetres"... Actually, we've always used inches here in Britain; we adopted the use of metric measurements when our currency became decimalised in 1970, but only where appropriate. Your American inches and miles came from our original Imperial measurements. We remain dual measurers here in Britain; pints of milk or beer; gallons of petrol. It's a bit daft; pints of milk now have to say 568 ml on the carton. It's a pint, for God's sake! Yes, we tend now to buy petrol in litres, but we still prefer to convert petrol consumption to miles per gallon, and rarely, if ever, do we think in kilometres. It gives my slide rule something to do; I have lots of European and other foreign friends, who all think in litres and kilometres ;)

@hansemannluchter643

Жыл бұрын

Yeah, but the thing is : Imperial measurements are kinda silly.. 3/8 of an Inch?? A pint? It's 500ml, or half a litre, for crying out loud!! Don't even get me started on the ridiculous currency-system you used to have, we needed specialised slide rules to do conversions!!

@marklammas2465

Жыл бұрын

@@hansemannluchter643 A proper pint is 568 ml 😉

Circular sliderules are the bomb, they are sooo cool, deserves every penny❤️❤️❤️ I was kinda wondering if they compensated for the lower accuracy in circular sliderules by shrinking the range to keep the accuracy across ranges the same?

fun fact, the small piocket slide rule you used in high school was actually the one that the astronauts in the apollo program took to the moon

@IMSAIGuy

2 жыл бұрын

Thanks! did not know that.

The movie Hunt for Red October had a circular slide rule used by the Russian navigator...

In Britain we are a bit weird, especially those of us over 40.. we were educated in metric but culturally we think in imperial. So we describe length in feet and inches, distance in miles, volume in pints and gallons and weight in stones but we were taught, from the mid 70's, in metric. So I would use metric to measure a window but would likely use feet and inches if I was describing the rough size of the window... so we're good with inches when measuring the Fowler 😉 V interesting video, I'm 52 and I was 14 when our school moved from slide rules and log tables to scientific electronic calculators. This was a controversial move because in 1984 scientific calculators were expensive. £30 in 1984 is £95 in 2023.. about $113 US and this was beyond many family budgets so we did a big push to raise money to buy school owned ones.

Kinda Kool!

When the round S.R. was made, it was made in "Great Britain" which used pounds, shillings and pence. Probably before decimalisation in 1971. Is my guess right?

I had an Otis King Model L, but it was lost in the "Great Flood" of 2011, sadly. I like OKs, but their scales were not the best, so their accuracy was no better -- though it should have been -- than a typical K&E or Pickett...and those had more scales. I would love a Fuller, though, or at least a well-3d-printed one with impeccable scales printed on it. That would be quite a joy to use. Of course, there are always volumes of tables. Yeah, imagine 10+ books on just sine values, going to the umpteenth decimal place. Great for nearly-quantum level calculation, or galactic navigation, where you actually need a boatload of decimal places.

I have one of the round telescopic sliderules..."made in London"....are they of any value?

@IMSAIGuy

3 жыл бұрын

I haven't checked lately. $50 to $100 maybe

@marklammas2465

3 жыл бұрын

I have one as well. "Otis King's Pocket Calculator". Don't sell it. Learn to use it! :)

I have a slide rule app on my phone that has straight, circular, spiral, and cylindrical slide rules on it. I am trying to figure out how the spiral slide rule works. So far I have figured out how to perform calculations using two hairlines and the D scale on the outside edge only. But I don't know how the C scale works. It starts at the centre with 100, and then spirals--15 times--and ends with 1000. And it has a variant that loops around 30 times! So it's not the same way as the spiral slide rule in this video. I would like to know how that works.

@IMSAIGuy

3 жыл бұрын

www.phase-trans.msm.cam.ac.uk/2009/OTIS/OTIS.pdf

@marklammas2465

3 жыл бұрын

@@IMSAIGuy Cheers for posting that link. I had that original full instruction leaflet for my Otis King calculator on my old phone, but it died without warning. My OK came with a partial photocopied example of the short version of the manual. Sadly no box or leather sheath. Good old Carbic! It's my favourite slide rule. Beautifully quirky, and mine is wonderfully battered and lived in :)

@marklammas2465

3 жыл бұрын

Look on the Android Play Store for "Circular Slide Rule". There's a very basic circular rule there, which is much simpler, quicker and easier to use than the app with several different rules. It's resolution is basic, like the tiny Russian KL-1 pocket rule, but it is an adequate substitute for a small slide rule, and genuinely usable.

I have an Otis King K series, I use it frequently

@IMSAIGuy

Жыл бұрын

'use it' ??? or play with it

@HarryFlashmanVC

Жыл бұрын

​@@IMSAIGuy use it, work frequently finds me on gas refineries and you can't take electronic devices into the Red Zone when the refinery is live, or you may find yourself sitting on a cloud playing a harp with your colleagues!

@HarryFlashmanVC

Жыл бұрын

​@@IMSAIGuy also, OKs are quite common in Britain, there's always a dozen or so on ebay. The number on the end of the tube is a serial one. Your one is a later model, so early 70's if the instructions mention New Pence and Pounds in Sterling Calculations then it's a post decimalisation of the British currency model which happened in early 1971. This allowed customers to use their regular Otis model for currency calculations because previously you needed one with a specific currency scale. Interestingly they didn't make a scale to help people convert old money to new.. probably because people would have realised how out of ocket they were! 😁

I don't think the spiral is as long as you guessed. Given the number of scales, it appears to only wrap around twice, which would make the length about 6" for a 1" diameter. Maybe I'm not seeing the scales to match them between spirals.

@IMSAIGuy

3 жыл бұрын

each scale is 20 wraps, so with your math 20 * 3" or 60"

@rickwise9910

3 жыл бұрын

@@IMSAIGuy I get it: there must not be many scales: the height (dimension parallel to cylinder axis) of each scale will be 20 * the height of one wrap of the scale. If each scale is 1/4" that means the total height of that scale is 5".

@marklammas2465

3 жыл бұрын

It's actually a 66" scale. I have one of these Otis King slide rules. I use it mainly at work. It's "built like a brick shithouse", as we say here in Britain, and will probably come to little harm if dropped. Mine is well lived in and battered since the early 1930s. Very easy to use, and accurate. Otherwise I use a pocket Keuffel & Esser duplex slide rule at work.

Bamboo isn't wood. Celluloid isn't really "plastic", since it's made from cellulose. "Post" bamboo slide rules where made by Hemmi in Japan. And there are slide rules with more scales than the one you show.

@IMSAIGuy

Жыл бұрын

I think if you talk about grass slide rules you might get some odd looks. 😎

@hansemannluchter643

Жыл бұрын

@@IMSAIGuy I don't know, engineering-types tend to be pretty hot on accuracy😋

@IMSAIGuy

Жыл бұрын

@@hansemannluchter643 oh I have many pedant viewers