Additional
Information: Medieval composer Franco of Cologne (c.1240-c.1280) not only wrote music, he also helped standardize rhythm and tone in his Ars cantus mensurabilis, setting him among the early theorists in western music.
Franco of Cologne Sites:
Franco of Cologne, (c. 1240 - c. 1280), Germany Franco of Cologne, (c. 1240 - c. 1280), Germany: Biographical data, recommended CDs, books and sheet music, bibliography, and links to biographical essays. (Franco of Cologne) http://stevenestrella.com/composers/composerfiles/franco1280.html
The Written Notation of Medieval Music The Written Notation of Medieval Music: Illustrated examination by Nigel remarking on clefs and staves, rhythm, note groups, and special symbols. Traces Franco's influence and shows forward and backward compatibility of the form. [PDF] (Franco of Cologne) http://www.bandsman.co.uk/download/medieval.pdf