BBb tuba 4RV with a pitch adjustment loop in the main tuning slide. Somewhat odd for the year of 1916, as the pitch reform from HP to LP in the German spoken areas was in 1920.
Randy Harrison
Proprietor,
Harrison Brass
Baltimore, Maryland USA http://www.harrisonbrass.com
Instructor of Applied Brass Performance
Maryland Conservatory of Music
Bel Air and Havre de Grace, Maryland USA http://www.musicismagic.com