Nashville, Tenn. -- The Fisk Jubilee Singers' first tour wasn't an immediate success, but their perseverance through financial hardship to find an audience took them around the world and kept their school afloat.Fisk University in Nashville, Tennessee, celebrated the singing group's 150th anniversary on Wednesday and reflected on a legacy that was built with their performances of slave spirituals, which kept alive not only the university but also a musical tradition.