More on slide rules

There's another kind of slide rules : the ones used by music lovers. The picture shows one of these . The so called "Musicalculor " was designed by Dr Chau-yuan Li back in the 60's and was cosidered having the same mechanism(with movable rule!) as those used in mathematics.

I found it very helpful especially in explaining to others the construction of the major scale; the formation of chords.... . In the instruction booklet, Dr Li suggests also its application on intevrals; modes; modulation; cannon & serial composition.