Slashdot Mirror
When Slide Rules Were Like Cellphones (hackaday.com)
szczys writes: Slide Rules and Pocket Protectors are the go-to items when making fun of old-time geeks. Forget the pocket protectors. Slide Rules were the first personal computers and a status symbol akin to what cellphones are today. Of course the general public wasn't attached to them, but engineers were. Before electronic calculators came around, everyone who needed to do some serious math owned Slide Rules. Stunningly easy to use and extremely effective, they have tick-marks placed on a logarithmic scale which makes complex multiplication, division, powers, etc. into visual calculations instead of mental ones.
An uncle was an honest-to-god rocket scientist. Things he built are sitting on the moon right now. When I was in elementary school he gave me a slide rule and told me I needed to learn how to use it. Pretty bad advice. :-) Within a couple of years, and before math classes could have used a slide rule, inexpensive 4 function electronic calculators arrived at the local department store. And each year's new offerings were much more capable.
Decades later while cleaning up I found it and brought it to work to show my fellow geeks, software developers. The CEO was passing by my office and noticed the crowd, poked his head in to see what was going on. He ended up staying about 15 minutes alternating between the manual and slide rule to figure out how to do different calculations.
Everyone was just so impressed with what a few sticks with tick marks painted on them could do. Hell, its how we built the machines that got us to the moon.
First some backgroung: Slide rules only give the characteristic of the answer not the mantissa. It is a fancy way of saying, it does not tell you where to place the decimal point. Thus often people fly through the slide rule all the way, without doing the decimal points for intermediate answers. Once you have the final answer, you eyeball the number, see which decimal point would be reasonable and jot it down. Saving valuable time not doing decimal work, during examn time.
This was the point that prof made: He would set up the problems in such way the answer would be off by a factor of 10 on purpose. A 230 volt, 10 cm dia motor would come in at 75 watts. But people who don't do decimals would write down 750 watts because, that is the reasonable answer for such a machine. Thus he would know which students have a feel for the numbers and answers and who blindly follow the procedures and write down whatever answer comes out of the formula. His complaint was that he lost a valuable filtering tool to judge which students are worthy of being considered for RAships.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
I stole a copy of "Why a Slide Rule Works" from the high school library and was way ahead of my math class the following year on logarithms & exponents. Asimov was a pretty good teacher.
I still have a Post VersaTrig around here somewhere...
My father, Jack Harker, was a very senior manager at IBM. He was Director of the San Jose [IBM] Labs in the 70's and 80's. He was also one of the quiet giants of the disk drive industry convincing IBM upper management to develop thin film disk heads and the original Winchester technology.
Jack loved to tell how in high level presentations when lots of figures and projections were being put up on the screen and the numbers didn't seem right, he would reach over and pull out his old 16" ivory K&E slide rule from his college days. The younger managers and engineers who had not seen him do this before would be flabbergasted, quite often offering to get him a calculator. He did this for two reasons. The first was to flummox the presenters and push them out of their comfort zone. The second was that he found a slide rule with its logarithmic scales was very useful for visually looking at growth projections. A quick look to see if the numbers actually made sense. Knowing my dad, I think the first reason was why he kept doing it. He enjoyed the looks of disbelief he got. Even more so after he quickly verified the numbers.
I sure do miss him.
What I find interesting is that it took a tremendously more advanced technology to render slide rules obsolete.
To make a slide rule, you need to figure out logarithms, then make exact marks on wood or something.
To make a modern calculator, you need to invent the microchip! You also need to invent a suitable display technology: light-emitting diodes or liquid crystal displays. We literally put a man on the moon before anyone was able to make a pocket calculator.
I love reading old science fiction stories set in the far future, where in the year 3423 or whatever people are still using slide rules. I imagine in the year 3423 people will still be using chairs, and probably spoons won't be too different... and back when those old stories were being written, slide rules seemed like that kind of basic item that wouldn't be going away.
P.S. Before the "pocket" calculator was invented, there were electronic desk calculators using Nixie tubes! Watch this video and think of how much labor it would be to assemble one of these. The soldering work alone guarantees that a typical college student could never afford one of these, but I'm sure NASA had calculators like this for engineers to use.
https://www.youtube.com/watch?v=mig3TeKh0aU
lf(1): it's like ls(1) but sorts filenames by extension, tersely
there were lots of possible slide bars. Ones for trigonometry, etc.. Most of the boeing planes up to the 747 were made by engineers who still used slide rules. Sure there were calculators and computing machines too, but slide rules were still in use by old timers.
Some drink at the fountain of knowledge. Others just gargle.
The digital caliper replaced the analog caliper. I miss the vernier scale, a really clever invention to squeeze out one more digit of precision than one would think possible. I doubt most kids today have any idea what a vernier scale is. The differential micrometer is another very clever device which works like a mechanical version of the vernier. My guess someone thought of it after seeing a vernier scale.
Some drink at the fountain of knowledge. Others just gargle.
I have Starett analog caliper and micrometer, and another Starett analog caliper in metric. I HATE digital calipers.
Other than the battery issue I don't really understand why you would dislike digital calipers. Our shop uses both analog and digital. The ONLY real advantage to analog is that you don't have to change batteries ever, which for some situations is nice. Otherwise the calibration procedures are the same and they work similarly effectively. Digital ones in my experience tend to be modestly easier to use but the difference is very minor outside of some specialty applications.
If you get drawings in both metric and US customary like us, carrying two measuring devices quickly becomes tiresome. Digital can switch between with a press of a button which is nice. Digital calipers can also output readings to a computer directly which can be really handy if you do a lot of it for stuff like PPAPs. There's nothing wrong with a good analog measuring device but there's nothing wrong with a good digital one either.