[R-390] was: Theory Question now: abacus (OT)

[rbethman]

Bill,

I realize this, and have knowledge of this, originating with "Napier's 
Bones".  Hence the Napierian Log basis of this ingenious device. The log 
of "e".  NOT to be confused with logarithm with a base of 10.

I simply refused to use this device to begin determining PPM of a signal 
generator's accuracy.

Why?  It is in the manual.

I'm NOT going to begin re-writing it.  Not to mention that it becomes 
"relatively" useless once the first component is replaced, AND is NOT 
calibrated against a known frequency standard.

Bob - N0DGN

Bill Hawkins wrote:
> A slide rule works on the principle of adding two numbers by sliding
> one identical scale against another. If you have two 12" rulers, you
> can add 4 + 2 by sliding the second ruler so that zero inches on it
> is opposite 4" on the other. Then go up 2" on the sliding ruler and
> read 6" on the stationary ruler. Works for adding fractions, too.
>
> The reason the slide rule works for multiply and divide is a property
> of logarithms. To multiply, you add the algorithms of the two numbers.
> Subtracting the log of the denominator from the log of the numerator
> give the answer for division. You don't need tables of logs if the
> scale on the rulers is logarithmic.
>
> Put another way, you do it just like you did on an Ohmite resistance
> slide rule.
>
> Bill Hawkins
>
>
> -----Original Message-----
> From: Dennis Wade
> Sent: Thursday, December 04, 2008 11:31 AM
>
> Well, I was taught in the early '70s as a high school vocational
> student.
> I LOVED my yellow Pickett slide rule...and even did logs.
> Trouble is...I'd need to be re-taught now.  I don't think many more
> classes after mine were taught slide rule techniques.
>
>              Dennis
>
>
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-- 
Bob - NØDGN