Sunday, December 16, 2012

Slide rules

I not only have a slide rule, I have two.

And in a miracle worthy of the season I knew exactly where they were despite not having laid eyes on them for at least 20 years.

So there they are, the white one is a Post, sort of a standard school boy slide rule of that time. It is enamel layered bamboo with a reversible slide. It contains all of the standard scales and is actually suitable for use for nearly all calculations. The yellow one is my "nice" slide rule, a more complex model, a Pickett, enamel layered metal, with many scales for complex scientific and mathematical computations. There is a bunch of stuff on there like log scales and some other stuff that I no longer remember how to use. I bet there is a Wikipedia article that would get me quickly back up to speed though.
Notably I did not need any refresher work to set the two slide rules up to solve a problem which was bandied about here recently.

The slide rules are set to figure the area of a circle with a radius of 1.5 miles. You set 1.5 on the D scale, that also gives you 1.5 squared on the A scale. Then you find pi on the B scale and read the answer on the A scale directly across from pi.

Just a tiny tish under 7.1 square miles.

4 comments:

Retired Professor said...

Ah, slide rules. JB has one with a leather carrying case. He keeps it on his desk.

It wouldn't take long to re-learn the basics. Even some of that logarithmic stuff, I'll bet.

Jimi said...

Good post. I like your slide rules, although calculators are easier and more accurate, there is nothing quite like sliding those pieces of scaled wood slats to get the answer to a complex math problem. I think I could do some math on those slide rules, too, but a refresher course on the basics might be needed for more complex calculations.

Do you own a buggy whip?

Santini said...

Exactly how much is a tiny tish?

Jimi said...

I did the calculation on my Mac and I see that that particular tish equals .0314 (about π/100). Yay. I got to use my π character again. Twice.