Early sonification device.
by Dr. d’Albe
http://en.wikisource.org/wiki/1922_Encyclop%C3%A6dia_Britannica/Optophone
http://www.probertencyclopaedia.com/cgi-bin/res.pl?keyword=Optophone&offset=0
Early sonification device.
by Dr. d’Albe
http://en.wikisource.org/wiki/1922_Encyclop%C3%A6dia_Britannica/Optophone
http://www.probertencyclopaedia.com/cgi-bin/res.pl?keyword=Optophone&offset=0