>>
>> In addition to discussing different slide rules, how about discussing
>> how to USE these slide rules in solving problems. After all, this is
>> a forum for the utilitarian beauty of the slide rule. Just my humble
>> thoughts.
>>
>> Cheers,
>> Amin


Yes indeed!

I too am very visually oriented (being an artist-a painter). I have
used a trick for years that in my opinion uses the "utilitarian beauty"
of the slide rule. It would also have great pedigogical value.
Explaining to yourself (or to others) exactly what is going on here
would sharpen one's understanding of the number system.

The choreography here is for a vintage Hemmi 260, made in 1960. She has
a full set of LL and LL/0 scales. On a rule with LL scales a big pain
in the glutius maximus in that the LL3 scale gets so compressed in the
last quarter or so to the right. This thing is sort of magifies that
end of the scale.

You set the number you want to raise to a certain power on the LL3
(say, 6.2). If you now set an exponent (say 3.9) on the C after lining
the left index up with the LL3(6.2), all you can read on LL3 is 1200
something.

Instead, set the 3.9 on the CI scale above 6.2(LL3). And rather than
reading at the right index, reset the hairline at CI(2.3025) and read
the answer (3.09)on the D. What I am doing is dividing log base e of
the number I am looking for by this number and get log base 10. The
setting is delicate: The hairline just kisses the 2.3 slightly to the
left.

This 3.09 is the entire log, charactoristic and mantissa. Extract the
mantissa and set it on the L scale on the other side of the rule. Above
0.09 on L is 123, so the charactoristic 3 gives 1230. A calculator says
that 6.2**3.9 is 1231.19...

If the exponent is negative and you are looking for a number on the far
right end of the LL/3, read the value off the DI (instead of the D)
from the L. If the above exponent is negative (6.2** -3.9), the method
gives 0.000812, agreeing with a calculator value in all three digits.

It doesn't always work this smooth, but I would say the thing gets you
2.5+ significant digits. And it's just fun to do. Do the settings with
a magnifying glass and see how close you can really get. I have never
seen this in a manual, and if it is, than I have invented it
independently.

It is possible to multiply on a set of LL-LL/0 scales and in some
ranges get four signicant digits.

It is also possible to raise numbers to a wide range of powers without
using the LL scales, using on K,A,B,C and D. (Like for instance,
something to the 0.444...th power.)

One way I amuse myself is to set something on the Hemmi 260 at random
and try to figure out what ALL the inplications of that setting are.

Take an analogue in music: it is said that the key of C major has not
been exhausted yet....

Take care,
Leo