Hi,
seen quickly on a TV program ( Cruising with Jane Mcdonald ) episode 4 series 3.
more details at
http://www.americanqueensteamboatcompany.com/blog/steam-calliope/
after more looking up it seems other boats have these as well
http://www.neworleans.com/things-to-do/music/history-and-traditions/steam-calliope/
Good wishes Peter B