Know How To Use a Slide Rule?

high_rolla writes "How many of you have actually used a slide rule? The slide rule was a simple yet powerful and important tool for engineers and scientists before the days of calculators (let alone PCs). In fact, several people I know still prefer to use them. In the interest of preserving this icon we have created a virtual slide rule for you to play with." Wikipedia lists seven other online simulations.

Comments

I feel bad

[planckscale]

My dad gave me his when I was a teen and said that he had used it for many years in college and the aerospace industry (Hughes). He gave it to me as a memento, and although he didn't keep it stuffed in his ass in Vietnam, it did carry a pretty significant sentimental value. It's lost; and although I did try to use it on several occasions, I only go so far as multiplication. It was a nice ivory color and had a leather carrying case. That thing probably helped launch 20 communication satellites.

Re:Of course

[Kadin2048]

A whole lot of engineers calculated a lot of transfer orbits (not just Earth-Mars) with slide rules. In some ways they can be a lot safer than using a calculator, since they don't give you a false sense of precision.

E.g., divide 52 by 7 on a calculator, and it will spit out 7.428571428571, a completely correct although ridiculous answer when dealing with real-world quantities, since it blows away the precision of the input numbers. Slide rules require you to constantly consider the number of decimal places that you want, and encourage you to only write down the correct number of digits (so you might do the same result and put down 7.4).

Personally, I think some of the best engineering ever accomplished by man has been conducted mostly by slide rules. I wouldn't go so far as to say that we've necessarily regressed since then -- computers are great, don't get me wrong -- but it's not right to simply write off slide rules. They had very distinct benefits and I think students would be well suited if they were kept around as a pedagogical tool.

Re:Nuclear slide rule.

[jdray]

When I was in the Air Force (many years ago), I was a Loadmaster on C-130 cargo planes. Every aircraft had a sliderule as standard equipment, and we had to know how to use it to calculate load balances for the cargo, even though we used electronic calculators. The idea was that if our batteries died, we had to have a fallback. When the numbers you're dividing are seven digits for the numerator and four digits for the denominator, and your precision is 0.1, long division on a scrap of paper isn't reliable.