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 learned how to use my slide rule...

[moosejaw99]

at around 10 years old. I've been using it ever since, and don't plan on ever stopping.

Re:I learned how to use my slide rule...

[Urantian]

Actually, one AND one is ONE.

At least

[edittard]

At least a slide rule is more accurate than excel 2007.

Re:Of course

[Daniel_Staal]

I've never had one required (courses tended to require graphing calculators by the time I got to them), but I found one in my grandpa's desk and learned to use it. Then I carried it with me to high school and gave it to anyone who asked to borrow my calculator.

Re:Of course

[mabhatter654]

but in reality, justifying precision more than 4 significant places is really difficult using proper scientific/engineering methods. For instance 4 decimal places in surveying takes you to an inch range even over a mile of distance with hand tools. Average slide rules can do 2-3 fancy ones can hit that last place.

Pilots know how to use slide rules.

[fiid]

The E6-B is a rotary slide rule that pilots use for calculating wind correction angles, time/speed/distance problems, conversion between units (i.e. weight of a certain number of gallons of fuel), and fuel consumption.

It's preferred over digital devices because they still work when the batteries go flat, they are easy to use with one hand, and some models are actually smaller.

http://en.wikipedia.org/wiki/E6B

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:Of course

[rrhal]

A slide rule gets you 3-4 digits faster than a calculator. You have to know how to use it.

I was in the last class in my high school that learned how to use a slide rule. I was in the first class in my college where owning a scientific calculator was required for entry.

As a freshman my Econ professor asked the class if anyone with a calculator would do a division for him. I was carrying an inexpensive plastic slide rule in my back pack. I did the division and said the answer. As he turned to thank me he did a double take and said "What is this?" taking the slide rule from me and holding it up. I said "Its new, a solar powered calculator that never needs batteries." "What will they think of next?" he pretended to marvel.

The point of that whole story is that about 15 people probably had pulled out a calculator and started to do the division and I was able to beat all of them by several seconds.

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.