The following is a list of famous people who are believed to have been polydactyl:
Anne Boleyn - said to have had eleven fingers, although she only had a double fingernail and a lump on her little finger[1] (http://www.straightdope.com/classics/a3_053)
... with a maximum effect when the axis starts "rolling" inside the groove. (Compare with graphic below.) Since this friction force is essential for the device's ...