Anyone here use slide rules back in the day?
- Thread starter Rusty Blade
- Start date
I still have a CRC press Handbook of Chemistry and Physics (The Big Book) that I bought in 1976. My chemistry teacher found a deal that if we bought 10 copies they would be $10 a piece. I rallied as many fellow students as I could and got the 10 pre-orders.
Came across another slide rule today. A circular one! With carry case and instruction pamphlet. For $1 I couldn't leave it.
It'll take a little getting used to but it's perfectly understandable with the slide rule knowledge I have. The back side is even covered with reference formulas.
It'll take a little getting used to but it's perfectly understandable with the slide rule knowledge I have. The back side is even covered with reference formulas.
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Awesome! My only problem would be I'd have to have you give me lessons on how to use it!
They are rarer than straight rules, so, I don't think you'll be needing any instruction soon! lol
Yeah, it's different. But I usually test myself with some simple calc (say 9 divided by 3), then look around the thing for the 0 or 1 mark on a 3. This thing has a triangular black pointer with an "I" in it (I'm thinking "indicator" point), and it was pointing at "3". It was only then that I discovered it has named D, C, C1, A, and K scales - just like a straight rule. So it can do squares and square roots, cubes and cube roots, along with multiplication and division. Perfect for what I do with rules. Very compact (like 3" diameter and 1/4" thick) so can more easily carry it in a shirt pocket. But not so small that the indicators are hard to see with aging eyes.
Yeah, it's different. But I usually test myself with some simple calc (say 9 divided by 3), then look around the thing for the 0 or 1 mark on a 3. This thing has a triangular black pointer with an "I" in it (I'm thinking "indicator" point), and it was pointing at "3". It was only then that I discovered it has named D, C, C1, A, and K scales - just like a straight rule. So it can do squares and square roots, cubes and cube roots, along with multiplication and division. Perfect for what I do with rules. Very compact (like 3" diameter and 1/4" thick) so can more easily carry it in a shirt pocket. But not so small that the indicators are hard to see with aging eyes.
Someone gave me a similar circular slide rule printed on plastic in sheets. Those rules were advertising favors. I do remember someone had a nice Pickett circular slide rule made of aluminum. It is intereesting that the only scales are A, B, C, CI, and D. Most basic 10 inch linear rules included K, L, S, and T. Werner von Braun and Sergei Korolov headed the US and the Soviet sides of the Space Race. Both owned, liked, and used the Nestler 23, which had the basic scales mentioned above.
In case anyone wonders, A and B duplicate one another. They are for squares and square roots in combination with C or D. C and D are for basic multiplication and division. They also duplicate one another. CI means C inverted. Some find it faster for division problems than using C and D in reverse from their use for multiplication. K is for cubes and cube roots in conjunction with C or D. L is for finding the logarithm of a number. S is for sines. T is for tangents.
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rbscebu
Girls call me Makaluod
Circular slide rules were very popular with aeroplane pilots/navigators. I also used one when ship navigating, particularly when offshore.
I used my new circular rule to compute the gas mileage on my Astrovan when I filled up recently. 215 miles on 12.76 gallons of gas. Calculated about 16.8 mpg.
Rechecked with a calculator when I got home: 16.84. Good enough for the girls I go with!
P.S. Almost 17mpg city with a big white box of a truck? Amazing!
Rechecked with a calculator when I got home: 16.84. Good enough for the girls I go with!
P.S. Almost 17mpg city with a big white box of a truck? Amazing!
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JCinPA
The Lather Maestro
I was the last senior class in my Jesuit boys high school that had to use them in Physics class. They let them use calculators the next year. I was also the last freshman class that had to wear a jacket at that school. And they had a smoking lounge for juniors and seniors who could smoke if they had a permission letter from their parents on file in the dean's office. I did. 
Imagine that! Would make heads explode today. Yeah, I'm that old.
Imagine that! Would make heads explode today. Yeah, I'm that old.
Considering that your mileage was 215 miles (also known as 2.15 x 100), your data is only good to two significant digits. Thus, your final answer should only be expressed in two significant digits 1.68 x 10 or 16.8 mpg.
Many calculators can express results in multiple significant digits, but people who use calculators tend to forget that the answers are only as good as the data from which those results were calculated. If your distance traveled were 214.9 miles and the gasoline used was 12.76 gallons, then the mpg would have been 16.84 to three significant digits. However, expressing the result as 16.8416927899 would not be correct, even if that is what the calculator shows.
In real life, it is unusual to have data that is precise to more than 2 significant digits unless you work in a sophisticated laboratory.
I had a very nice slide rule in a leather scabbard I guess my son has it as a novelty now. I was out of college a couple of years before electronic calculators became available.
Slide rules?
"No Pushing"
"No Pushing"
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I used slide rules all through high school and college. However, when I started to work in a research lab, I needed a calculator. The two options at the time were the Texas Instruments SR-50 calculator and the Hewlett Packard HP-35. The company refused to pay for personal calculators, so I saved up and purchased the SR-50. It cost a week's take home pay which was quite an investment considering the dire state of my finances at the time.
Today, you can purchase a calculator with similar scientific capabilities for $10-15, just a fraction of what my first one cost.
Today, you can purchase a calculator with similar scientific capabilities for $10-15, just a fraction of what my first one cost.
Anyone remember the giant demonstrator slide rules that hung atop blackboards in high school classrooms?
- Thread starter
- #96
Isnt math wonderful. I have really enjoyed reading the posts on this thread. I was a math geek in high school. I used to do the complex bonus math questions at the end of the math book just for fun on weekends. I wish I could find my slide rule from back in the day.
By any chance, were you inducted into the Mu Alpha Theta honor society. The name spells "MATH". It was my favorite honor society. I loved the logo representing the Pythagorean theorem. As a fellow math geek, I wore my pin proudly.
I took an after school class when I was in jr high. I remember it being fun. Now I just ask Google (she seems to know everything).
- Thread starter
- #99
Sadly we didnt have that society in my school. As much as I loved math I was one of the kids who used to hang out by the back door and smoke.
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