These hits of the 20s are almost exactly a century old as I write, and yet they sound beamed from another planet. The jazz features no solos, and the blues sounds almost happy. Bizarre romps from Al Jolson and Eddie Cantor are clearly meant to be comedy, but the punch of the jokes is lost to history. Get on the right wavelength though, and you can still dance the Charleston to jaunty alien tunes like “Copenhagen.” Cleaning up the set is a signature American composition, Gershwin’s “Rhapsody In Blue.”