DISRAELI DOCUMENTS
This patent covers Angelo Benato's design for a derailleur including 'flippers' to move the chain. At this point Angelo seems to have been concentrating on 'flippers' above the chainstay - requiring the rider to back-pedal when changing. He produced a design (but no patent) with the 'flippers' below the chainstay - enabling the rider to keep pedalling forward.
Note that this patent dates from 1938, whereas Vittoria had patented a 'flipper' design as early as 1934.