[Blindmath] Where can I get a Braille Slide Rule?

[Nelson Blachman]

  I'm sorry, Jerry; I don't know where you might get a Braille slide rule.

  Sixty-some years ago, when I attended college and could see, I had a 
circular slide rule about 10 inches in diameter with two transparent 
pointers turning around the center, the upper one being carried around by 
the lower one so that the angle between them was preserved to indicate the 
ratio of two numbers to which the two pointers had been set, which might 
then be used to multiply or divide a third number (or just 1).

  But the two pointers had a black line ruled on them from the center post 
outward, and I could see the numbers on the disk through the transparent 
pointers.

  If the numbers are Braille, you can't feel them through the pointer.  So 
how can a Braille slide rule work?

  Perhaps the pointers have wide slots in their middles through which you 
might feel the numbers beneath, with a stiff wire replacing the black line 
down the center.  But the edges of each pointer could get in the way of 
feeling the numbers below.

  Nelson?
----- Original Message ----- 
From: "Jerry Richer" <jerry at ChirpingBat.Com>
To: <blindMath at nfbnet.org>
Sent: Friday, July 10, 2009 5:01 AM
Subject: [Blindmath] Where can I get a Braille Slide Rule?


>     Do you know where I can get a Braille Slide Rule?  I used to have a
> circular one.
>
>               Jerry
>
>
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