(C Algorithm) "ringing changes"

[Peter S. Shenkin]

A good intro to change ringing is to be found in the Encyclopedia 
Britannica.  I have the 13th edition (= the  classic 11th plus supplemental
volumes), but I looked in a recent edition and the article appears unchanged
since those days.

Incidentally, I also got interested via "The Nine Taylors"  (or is it 
"Tailors"?).

I want to program my Mac to ring changes....