Ethnomusicology is a fascinating subject, and nowhere more so than when it comes to the music of African-Americans.  During the New Deal researchers recorded the oral histories and music of former slaves who were by then in their eighties and nineties.  Most famous, of course, was the work of Alan Lomax, who worked with Zora Neale Hurston among others to record and document this soon-to-be-gone-forever piece of American history and folklore.  Graduate student Bob Hester spent a year tracking down the roots of a half dozen slave songs.  The tale goes from South Carolina to Augusta, Georgia with the help of a soldier from Brooklyn.