This item at Smith’s Tavern is an automobile horn, circa 1920s.
At the beginning of the 20th century, the quest for effective in-car signaling devices changed the acoustics of American roads forever. Automobile owners had their choice of whistles, sirens and bells so they could manually alert pedestrians and other road users.
The bulb horn – like the one at Smith’s Tavern (which is missing the rubber bulb) – sound was considered more novel and penetrating than a bell. The horn was attached by a fixed mounted stem and operated by squeezing a rubber bulb attached to the metal horn. The bulb horn made a sound usually resembling a “honk”. The vehicle operator used the horn to warn others of the vehicle's approach or presence, or to call attention to some hazard.