What's this?

[rhu]

So I've figured out what the mysterious symbol in this picture means, but I don't know what it's called or the derivation of the symbol. Any thoughts?

From Misc

Comments

[goldsquare.livejournal.com]

The greek letter Pi?

Let me rephrase. That symbol at the bottom is the letter Pi. Is that the one that you find mysterious?

[530nm330hz.livejournal.com]

No, I mean the figure at 1.745 on the A/B scales. (Technically, it's at 0.0174532)

[michelel72.livejournal.com]

Maybe grad??? (I got there from the Wikipedia page on "radians", and maybe the symbol is meant to be a "G" for grad? I'm taking a complete flyer on that.)

[530nm330hz.livejournal.com]

Interesting idea, but since the symbol represents the ratio of one degree to 1 radian, I don't think grads will show up here.

But a stylized "g" was certainly where I started.

[lucretia-borgia.livejournal.com]

I assume you've seen this. I looked in the manual for my Sterling, but the symbol isn't on the rule. I can't find my circular slide rule, which is disturbing, but the manual was also still there in its case. Lot of good that does. It had some really, really useful chemistry/physics constants and metric/British (well, American now, I guess, since the Brits have some sense) unit conversions.

[530nm330hz.livejournal.com]

I had not found that page. A stylized rho to mean radians? Plausible.

This is a Danish slide rule by Ole Jørgensen, for what that's worth.

[530nm330hz.livejournal.com]

And it appears to actually be a collectable with non-trivial value. Not that I plan to sell it; it has sentimental value to me.

[sethg]

Could this be a stylistic variant of ϑ (U+03D1 GREEK THETA SYMBOL)?

[toonhead-npl.livejournal.com]

It's π/180 and useful when dealing with radians apparently: http://www.caffnib.co.uk/slides.htm (search for C:1.745)

Now why THAT symbol, I dunno.

Mystery Solved!

[fauxklore]

I don't know what the symbol is called, but I have figured out a simple and logical (elegant, even) explanation for it.

It is used to convert between degrees and radians, right? In fact, to TURN degrees into radians.

Now, take the symbol for degree - that little raised circle thing.

The symbol for radian is the letter "r".

TURN the "r" upside down and attach it to the degree sign - and voila!

So, basically, it is rebus.

[rymrytr.livejournal.com]

You could send a picture and request to
http://www.rekeninstrumenten.nl/index.html
the Danish Slide Rule Collector's Museum and Group.

Email = Otto van Poelje poelje@rekenlinialen.org