QUICKSILVER MESSENGER SERVICE Avalon Ballroom San Francisco Concert (1967 US promotional-only 5 x 7 & 1/2 postcard for the April 21-22 1967 concerts at the Avalon Ballroom San Francisco which featured Quicksilver Messenger Service Johnny Hammond & His Screaming Nighthawks Charles Lloyd & North American Ibis Alchemical Co.) The Family Dog was a loose collective of free spirits managed by Chet Helms a contemporary of Bill Graham who put on rock dances at the Avalon Ballroom more or less continually from 1965 to 1970. These almost-nightly events like those hosted at the Fil