The ark lands after The Flood. Noah lets all the animals out. Says, "Go and multiply." Several months pass. Noah decides to check up on the animals. All are doing fine except a pair of snakes. "What's the problem?" says Noah. "Cut down some trees and let us live there", say the snakes. Noah follows their advice. Several more weeks pass. Noah checks on the snakes again. Lots of little snakes, everybody is happy. Noah asks, "Want to tell me how the trees helped?" "Certainly", say the snakes. "We're adders, and we need logs to multiply."
This reminds me of the cartoon diagram of a computer posted in our university's IBM 7044 computer room circa 1968. I've forgotten most of it, but I still remember the snake swimming in a little pool of water, subtitled “Floating-point adder”.
There are some things that a slide rule is superior for -- one item I can think of is visualizing an arbitrary range of fractional values. For example, lets say you need a capacitor and a resistor with values in a particular ratio. Any pair will work in your given circuit (within reason), as long as that ratio is maintained. You have a drawer full of various resistors and another of capacitors, and need to find a pair that will work. So you set your slide rule to that fraction (let's say 1.7 / 3.3), and you can then pull up any resistor and determine which size capacitor can be used by glancing at the slide rule. (Of course you still have to keep track of the magnitudes in your head, but being in the habit of that makes you a better engineer anyway).
I implemented Ohm's Law as you describe for an iOS App some years back [1]. Tried also to figure out how to do it in Javascript (still learning, love it if someone could really make it nice for the rest of us to use) [2].
"There are some things that a slide rule is superior for -- one item I can think of is visualizing an arbitrary range of fractional values."
Exactly, similar to the way log scales make visualizing a range of results across the slide rule no matter what one is doing.
Similarly, I have a number of good digital multimeters but I also keep several analog AVO meters, https://en.wikipedia.org/wiki/Avometer, to give me a sense of proportion if I'm adjusting something (nulling a discriminator etc.).
If all you need to do is add, Comptometers are the fastest machines so far invented. They are fast because you can enter entire numbers at once (as a "chord" with multiple fingers pressing multiple digits at once). No need to hit "+" key or pull a lever between numbers, each button press is an immediate addition.
I'm thinking of making an electronic version- it would have the same Comptometer key layout, but have more operations (for example, hold multiply "shift" key down while entering number for a multiply).
Must be in the air, I just watched a YouTube recommended vid by Mathologer on the circular slide rule that was interesting. https://youtu.be/ZIQQvxSXLhI
I love that it's still used in watches. Some brands have it build into watches bezel, with some predefined marks for popular conversions like galons/liters, miles/nautical miles/kilometers and so on.
It looks fun and is fun. Of course the rule itself is very limited as you basically have to figure out where is the decimal point by yourself (even for small numbers) but it's actually very precise and may be useful with practice.
Below some examples that are not very expensive [1], also a Casio manual [3] I found very helpful and visually appealing.
Definitely in the air. I just watched that video last week and was blown away by the rubber band analogy. So simple and intuitive what's happening as the wheel takes up the infinitely-stretching rubber band.
I always thought I understood logarithms—and I actually did somewhat—but that visual really drove home the "continuous ratio-ing" that's happening as the scale is built.
These computers had slide-rule like cylinders that would rotate. As you aimed the gun sights "at" a target, the gun's coordinates were being mapped to a cylinder, which would move the gun a different direction (you have to aim the gun "higher" the further away the target is, to account for gravity "drooping" the bullet).
In effect; the weirdly shaped cylinder inside the fire-control computer is a pre-computed solution that maps x/y coordinate inputs to a z-coordinate output (where "z" would be fed into the gun's raw aiming system).
The different parameters of the gun were programmed in with gears and cranks, moving the cylinder around physically.
Its a 20-minute video. The cylinder mechanism (of 2x inputs mapped to 1x output) is specifically talked about here: https://youtu.be/gwf5mAlI7Ug?t=636 . Carefully crafted cylinders could be any pre-computed 2-input / 1-output function.
---------
Mechanical computers are fun. Slide rules are but the simplest kind. People were using more complicated "mechanical computers" for very serious combat / rangefinding / etc. systems just a few decades ago, before the advent of modern digital computers.
Another cylindrical rule is the Thacher Cylindrical Slide Rule. It's a cylinder with many rules marked out on it, that rotates in a set of fixed rules. All told it is the equivalent of a 66 foot long conventional slide rule.
I actually picked one up out of the garbage bin at the university I worked at. It didn't have an inventory sticker so they had to toss it according to the rules.
Mechanical computers are really cool. Veritasium just did a 2 part video on them. The second goes over some ML applications for the future. You can make a really tiny and energy efficient mechanical chip to do some cool things.
Consider that this slide is doing two things for you: it remembers the conversion factor (for a bunch of difference conversions), and it does the multiplication or division.
I want one of these. Right now, I do this conversion a lot more than usual. Over time, I have mapped many of my familiar Imperial unit touchstone type references onto Standard International units, so I am largely good to go, but this would have been very useful during the process.
And what I mean here is just ones sense of scale and ability to mentally estimate and work with familiar ratios to arrive at solid first order approximations. These are important, in that one can set expectations about the answer quickly and accurately. Doing that is a great check on the problem overall and or makes mental analysis quick and robust.
It is all the little things, like a sheet of paper being 0.004" or 0.1mm. Looking at something, say to understand whether it can be manufactured, or maybe features are too small or large and fall outside process limits.
Or, given a force, something happening, or one suspects may have happened, working backward to arrive at root cause of failure, having that kind of info "in head", useable directly in that internal way, knowing how it might appear, feel, be seen, sound like, is high value.
Tools like this really help with all that. Combining the data with motions, the slide, how far, etc all build robust mental connections. It just starts happening. For me at least, I just begin to "know" whether it make sense, will fit, break, etc...
When I was in school in the late 60s a slide-rule company gave a special offer to us, which all of our parents (wanting us to succeed in the bright technological future) duly bought into. As far as I know, none of us ever actually used them, preferring paper log tables.
We were also taught how to use mechanical adding machines, possibly the last people to be lumbered with this information, which mercifully I have completely forgotten.
I was probably the last generation in the US in the 1970s to willingly learn slide rules - the HP-35 had been out a few years and new scientific calculators already made the demise of slide rules pretty obvious to even us nerdlets.
One of my prized inheritances from my engineer father is his slide rule (complete with leather case).
I tried to find a place to buy a new slide rule for my 15-year old. I've got twins in different schools, one school doing a lot more math than the other, and I wanted to get him going on logarithms. Couldn't find a new one, just antiques on ebay, etc. I ended up making one of the paper ones, but they're not the same.
I don't think anyone still makes new slide rules, except for the E6B flight computer which is rather specialized. However, you should be able to get a metal Pickett slide rule on ebay for a reasonable price; they're great slide rules and being metal rather than wood will tend to hold up better over the years (moisture can really mess up a wood slide rule). Something like this: https://www.ebay.com/itm/234503446574
I thought about getting into hand making them, figured out most of the techniques that I can do in my garage with some components (the end brackets, and cursor runners) being made on a 3D printer. But I'm hung up on where to get the cursor springs from, or what would be a good substitute. One of these days I may revisit the topic.
Concise in Japan[1] still make circular slide rules (the 300, 270N, 28N 27N). I bought a couple from them a few years ago. Good quality, and work well.
My sister is 3 years older and she still learned slide rule in high school but I didn't. Being a nerd I had my dad teach me though. One of the key things is just the right amount of grease in the tracks.
I love slide rules. I'm old enough to have had one with a belt case that I brought to school. But I have to ask, what is wrong with a ridiculous amount of precision?
I think these are essentially nomograms. I seem to recall in college engineering back in 90s they taught us how to design nomograms for simple functions.
[+] [-] evilotto|3 years ago|reply
[+] [-] vincent-manis|3 years ago|reply
[+] [-] derekp7|3 years ago|reply
[+] [-] JKCalhoun|3 years ago|reply
[1] Perfboard (5th screenshot shows it): https://apps.apple.com/us/app/perfboard/id46595187
[2] SlideRule.js: https://github.com/EngineersNeedArt/SlideRule
[+] [-] hilbert42|3 years ago|reply
Exactly, similar to the way log scales make visualizing a range of results across the slide rule no matter what one is doing.
Similarly, I have a number of good digital multimeters but I also keep several analog AVO meters, https://en.wikipedia.org/wiki/Avometer, to give me a sense of proportion if I'm adjusting something (nulling a discriminator etc.).
[+] [-] goache|3 years ago|reply
[+] [-] ASalazarMX|3 years ago|reply
[+] [-] jhallenworld|3 years ago|reply
https://www.youtube.com/watch?v=swCy6pQSEpk&list=PLLFpXNanTP...
Inspired me to buy a Comptometer:
https://en.wikipedia.org/wiki/Comptometer
If all you need to do is add, Comptometers are the fastest machines so far invented. They are fast because you can enter entire numbers at once (as a "chord" with multiple fingers pressing multiple digits at once). No need to hit "+" key or pull a lever between numbers, each button press is an immediate addition.
I'm thinking of making an electronic version- it would have the same Comptometer key layout, but have more operations (for example, hold multiply "shift" key down while entering number for a multiply).
[+] [-] pwr-electronics|3 years ago|reply
[+] [-] dahart|3 years ago|reply
[+] [-] szszrk|3 years ago|reply
It looks fun and is fun. Of course the rule itself is very limited as you basically have to figure out where is the decimal point by yourself (even for small numbers) but it's actually very precise and may be useful with practice.
Below some examples that are not very expensive [1], also a Casio manual [3] I found very helpful and visually appealing.
[1] Seiko SSC632, Seiko SRPB59J1, Casio EF527D-1AV [2] https://support.casio.com/answer.php?rgn=4&cid=002001009001&...
[+] [-] function_seven|3 years ago|reply
I always thought I understood logarithms—and I actually did somewhat—but that visual really drove home the "continuous ratio-ing" that's happening as the scale is built.
[+] [-] perilunar|3 years ago|reply
Ha. The famous E6B flight computer is a circular slide rule.
Edit: it's mentioned in the video.
[+] [-] dragontamer|3 years ago|reply
What I didn't realize was that the mechanical principles of slide-rules were applied to fire-control computers on WW2-era Battleships.
https://en.wikipedia.org/wiki/Mark_I_Fire_Control_Computer
These computers had slide-rule like cylinders that would rotate. As you aimed the gun sights "at" a target, the gun's coordinates were being mapped to a cylinder, which would move the gun a different direction (you have to aim the gun "higher" the further away the target is, to account for gravity "drooping" the bullet).
In effect; the weirdly shaped cylinder inside the fire-control computer is a pre-computed solution that maps x/y coordinate inputs to a z-coordinate output (where "z" would be fed into the gun's raw aiming system).
The different parameters of the gun were programmed in with gears and cranks, moving the cylinder around physically.
For more details, see: https://www.youtube.com/watch?v=gwf5mAlI7Ug
Its a 20-minute video. The cylinder mechanism (of 2x inputs mapped to 1x output) is specifically talked about here: https://youtu.be/gwf5mAlI7Ug?t=636 . Carefully crafted cylinders could be any pre-computed 2-input / 1-output function.
---------
Mechanical computers are fun. Slide rules are but the simplest kind. People were using more complicated "mechanical computers" for very serious combat / rangefinding / etc. systems just a few decades ago, before the advent of modern digital computers.
[+] [-] pugworthy|3 years ago|reply
https://www2.humboldt.edu/scimus/NorthCoastInst/ThacherCalcu...
I actually picked one up out of the garbage bin at the university I worked at. It didn't have an inventory sticker so they had to toss it according to the rules.
[+] [-] wlesieutre|3 years ago|reply
https://en.wikipedia.org/wiki/Curta
https://www.youtube.com/watch?v=loI1Kwed8Pk
[+] [-] 7thaccount|3 years ago|reply
[+] [-] jhallenworld|3 years ago|reply
https://americanhistory.si.edu/collections/search/object/nma....
Consider that this slide is doing two things for you: it remembers the conversion factor (for a bunch of difference conversions), and it does the multiplication or division.
[+] [-] ddingus|3 years ago|reply
And what I mean here is just ones sense of scale and ability to mentally estimate and work with familiar ratios to arrive at solid first order approximations. These are important, in that one can set expectations about the answer quickly and accurately. Doing that is a great check on the problem overall and or makes mental analysis quick and robust.
It is all the little things, like a sheet of paper being 0.004" or 0.1mm. Looking at something, say to understand whether it can be manufactured, or maybe features are too small or large and fall outside process limits.
Or, given a force, something happening, or one suspects may have happened, working backward to arrive at root cause of failure, having that kind of info "in head", useable directly in that internal way, knowing how it might appear, feel, be seen, sound like, is high value.
Tools like this really help with all that. Combining the data with motions, the slide, how far, etc all build robust mental connections. It just starts happening. For me at least, I just begin to "know" whether it make sense, will fit, break, etc...
[+] [-] zabzonk|3 years ago|reply
We were also taught how to use mechanical adding machines, possibly the last people to be lumbered with this information, which mercifully I have completely forgotten.
[+] [-] xyzzy21|3 years ago|reply
One of my prized inheritances from my engineer father is his slide rule (complete with leather case).
[+] [-] bediger4000|3 years ago|reply
Does anybody make new slide rules?
[+] [-] floren|3 years ago|reply
[+] [-] derekp7|3 years ago|reply
I thought about getting into hand making them, figured out most of the techniques that I can do in my garage with some components (the end brackets, and cursor runners) being made on a 3D printer. But I'm hung up on where to get the cursor springs from, or what would be a good substitute. One of these days I may revisit the topic.
[+] [-] wmwragg|3 years ago|reply
[1] https://www.sliderule.tokyo/products/list.php
[+] [-] HappyJoy|3 years ago|reply
[+] [-] throw0101a|3 years ago|reply
---
The Professor Herning YT channel has a bunch of videos on both using slide rules and reviews/comparisons of various ones:
* https://www.youtube.com/c/ProfessorHerning/videos
The "Practical Slide Rule" [0] and "Basic slide rule theory and use" [1] playlists are a good intro:
[0] https://www.youtube.com/playlist?list=PL_qcL_RF-Zyu6ugp3E2nB...
[1] https://www.youtube.com/playlist?list=PL_qcL_RF-ZyvJYtIr9NRX...
---
https://news.ycombinator.com/item?id=30971066
[+] [-] GeorgeTirebiter|3 years ago|reply
[+] [-] tedunangst|3 years ago|reply
I spent a long time staring at the picture until I figured out the bottom is the second row, and there are four rows of numbers below the bottom.
[+] [-] agumonkey|3 years ago|reply
[+] [-] albert_e|3 years ago|reply
[+] [-] zwieback|3 years ago|reply
[+] [-] xyzzy21|3 years ago|reply
https://www.youtube.com/watch?v=ZIQQvxSXLhI
[+] [-] s0teri0s|3 years ago|reply
[+] [-] pkaye|3 years ago|reply
[+] [-] zanethomas|3 years ago|reply
[+] [-] marcodiego|3 years ago|reply