In the excellent "McNeil Modern Guitar Method", an American publication of 1930 copyright, Forster Music Co.Inc. he describes the Capo d`astro as follows:- "A contrivance which can be fastened across the fingerboard, to raise the pitch of all the strings at once.(Not used by legitimate guitarists)" It would appear that even in the 1930`s the mothers of certain guitarists had doubtful morals!