I can’t think of a better emoji for a musical instrument of the Steam Age than that of the calliope.
A 19th century American invention, it was a steam-powered organ, played outdoors, on showboats and circuses. Those on fairgrounds were showy affairs, mounted on a carved, painted, and gilded wagon, pulled by horses.
Where an organ produces notes by the passage of air through pipes, a calliope makes music by puffing out steam through a series of gigantic whistles. It was very loud, and could be heard from blocks away, but it didn’t have the sonorous depth or the melodious harmony of an organ.
It had a brass keyboard for the same reason that steampunk gadgets have a lot of brass in them. Brass, an alloy of copper and zinc, is more resistant to heat and moisture from the steam.