This is a super early Adolph Sax in nickel silver, 50 Rue Saint-Georges, serial number 8407. It is one of the earliest alto's we have personally come across. It has a odd shaped neck which differs from the later Saint Georges models. The alto was restored by Barnard Instrument Repair in 2015. After it was restored we discovered the alto is pitched very close to 440 and tunes quite well.
You can see this alto on display in the Saxquest Museum located in Saint Louis Missouri.