We recently added some french horn mouthpiece examples from the 1920-early 1930s. These examples were in a box located at a music store old inventory, before we added to our collection. Vincent moved his factory to the Bronx in 1928, so perhaps from that timeframe.
Note the similarities to a well known, modern Trumpet mouthpiece manufacturer.
Bach French Horn mouthpieces
(L to R: later New York model, 2 earlier New York examples for comparison)