Frazz by Jef Mallett for October 08, 2015

She’s thinking: Did Caulfield just old-school me?

I loved my slide rule. It was a wand of mystery whose spells I never could cast. Thank God Hewlett Packard released a calculator with special functions the year I needed it. But my slide rule is still cloaked in mystery, carefully preserved in my desk drawer. Some days I feel its dark magic radiating to me. Life is fun!

I thought the slide rule was “One at a time and no pushing”

Nope. The slide rule is “feet first”.

I still have one of mine, but I doubt if I could really remember how to use it, even though I was pretty proficient at the time.

My grandfather worked for NASA to help put a man on the moon, they did all their work on sliderules. When my mother became a teen with a calculator, she challenged grandpa in a calculation-race of a dozen problems. He finished before she was even halfway done.

Ah!!! Slide rules.I still have a couple including my Otis King Calculator, a six-foot slide rule wound round a set of tubes!

It could do calculations to three significant figures!!!! (IIRR)

Ah the memories. It was a status symbol at school because it meant that you were an all-knowing senior.

“Slip stick”

E to the X! dX! dY!E to the X! dX!Secant, cosine, tangent, sine,3.14159,Square root, Cube root, Log of Pi,dsINtegrate M, RPI!

- my engineering school cheer

The one big drawback to a slide rule is that it can’t perform addition or subtraction functions.

For a high-school physics exam, we were told we couldn’t use electronic calculators. I brought in my slide-rule. (Going out of fashion, but not yet obsolete, calculators were not yet ubiquitous) The physics teacher stood by my desk for most of the test, trying to figure out if I actually could use it or I was yanking his chain. The answer was both. Several other students protested, but he allowed it because it was NOT electronic. :)

Heck, I used one for a test three years ago. Ordinarily I use a calculator app, but the teacher didn’t allow any web-capable devices during the test. I had also used it to finish a homework earlier in the semester when my battery died.

And no, I’m not old enough to remember slide rules. But why should that stop me?

When I was going to college, electronic calculators were just gaining traction. The Bomar Brain was a favorite, if one had the money (about $200). Most of us used slide rules, which don’t add or subtract. Still have a few slide rules in my desk drawer.

The slide rule Mrs. Olsen is holding is a Pickett. They were all yellow, while K&Es and Posts were not. Picketts were typically preferred by electrical engineers due to the way they laid out the scales. I have a K&E because I’m an ME. Civil engineers seemed to like the Posts.

Slide rule accuracy slipped after 3-4 calculations to only 2 digits of accuracy unless you slipped up on the decimal point. Calculators give you 8-12 digits and keeps the decimal point in the right place. Slide rules gave you a general direction of the answer in a calculate to 3 decimal points, mark with chalk, and cut with an ax process.

I still have my Pickett circular rule. In school we were only allowed a rule that would fit in your pocket. So the teacher with his 10" would always be better than our pocket 6" ones. (mind out of gutter please!) Then my Mensa buddy discovered the circular ones were as good as a 10" and still met the shirt pocket rule.

I spent half a year in Grade 5 learning how to use a slide rule. By the time I was in Grade 10, pocket calculators had come out (hideously expensive, but even so…) and the “slipstick” was all but obsolete.

Slide rules work by adding and/or subtracting logarithms. To multiply two numbers together, you add their logs. Thus, you find one number on one stick, move the “1” on the other stick to it, then find the other number on the other stick, and you have added the logs, and you have the result.

To divide two numbers, you subtract the logs, so you find one one number on one stick, and pair the other number on the other stick up with it, then go to the “1”, and you’ve got the answer.

The only trick is that it doesn’t tell you where the decimal point goes. That you have to figure out yourself. Oh, and slide rules normally have more than just the two scales. They have some for trig (Sine/Cosine/Tangent), and some for squares/cubes, enabling you to also find square roots and cube roots.

I learned a very important lesson from a slide rule, which has been applicable to all of the new technology since. That is that:If you are doing just fine without it, don’t buy it. There will be another new something to replace it out before you would need to use it, and if you buy all the new wonderful technology, you will be wasting a fortune, not even considering the cost of the closet required to store it along with the slide rule.

i think i only used C and D, the really cool one was hanging on the wall in front of the blackboard. must have been 6 feet long

In high school in the 60’s, we were expected to use them. I have my father’s Dietzgen Microglide. It has teflon coating on the inner slide edges, and a leather holster. My first slide rule was the 6-incher that came with my Lakeside Draft-A-Plan Kit. It’s wood and has only 6 scales. I keep it in my truck, and check gas mileage on it after I do the calculation in my head. My Pilot tells gas mileage on the instrument display, but when I fill up, the displayed number is inaccurate.

I used to know how to use a “swindle stick” 60+ years ago.

A few years ago I asked a couple of engineering students working for me part time if they still use slide rules and neither of them knew what I meant so I explained it was a mechanical calculator that had built civilization and more recently was instrumental in saving the lives of the crew of the Apollo 13 space craft when it had nearly been lost in space because of the massive explosion of it’s primary oxygen tank. Since they were still perplexed I brought mine to work the next day and in a timed contest of simple multiplication and division beat them both on their cells and calculator to the answers 4 out of 5 times. They gained a new respect for old school and asked me to tutor them in it’s use so they could impress their classmates. Better yet, no batteries or network needed.

in ’74 my Engr. class was the last required to learn to use slide rules, right next to our class of calculators

I remember how thrilled I was when my father gave me his K&E log-log duplex dectrig — what a great name!

Probably no device has become obsolete as fast as the slide rule did when calculators became semi-affordable.

My husband still has his slide rule from high school. He also has the huge one my engineer father used for many years.

My brother was an electrical engineer before calculators came out. I kind of inherited his engineering slide rule when I was in Junior high and I learned to use the basic addition, subtraction, multiplication, and division functions, but I never did learn how to do the higher functions. (Just don’t ask me to demonstrate now because I can’t remember how it worked).

I’d like to see the merchant do trig and logs on an abacus!

Calculators are better because they are more portable, give more precision, and because they keep track of the decimal point. Slide rules are better because they are faster, and because they don’t keep track of the decimal point, forcing you to know what is going on, and make sure you get a “reasonable” answer (whereas with a calculator, people often just accept whatever it says).

Hubby always said he could use a slide rule too—to draw straight lines.

Logic and reasoning are fun to use in creative ways!

I find it difficult to believe that Mrs. Olsen graduated High School on an academic program about the same time I did (assuming she’s close to retirement) without having some idea how a slide rule worked.

Tell that to my 4th grade self. Back then I didn’t see why it was necessary to show work to add numbers like 255 and 342

If you ever used a slide rule you can remember the first attempt— and what it taught you about common sense.

Two times two is, uh, three point nine nine nine nine—

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