DISRAELI DOCUMENTS
This advert is (slightly) interesting because it offers a 3 speed derailleur that can be fitted to all brands of bicycle. This is significant because I believe that the initial 1910 design of the Boizot Tri-direct required a frame with a specially adapted chainstay on the gear side. Things may have moved on by 1913.
(Source gallica.bnf.fr/ Bibliothèque nationale de France)