the concert repertory is the Prelude to Wagner's Das Rheingold (1854) wherein low horns and bass instruments sustain an E throughout the entire movement. The atmospheric ostinato effect that opens Beethoven's Ninth Symphony, which inspired similar gestures in the opening of all the symphonies of Anton Bruckner, represents a gesture derivative of drones. One consideration for composers of common practice keyboard music was equal temperament. The adjustments lead to slight mistunings as heard against a sustained drone. Even so, drones have often been used to spotlight dissonance purposefully. Modern concert musicians make frequent use of drones, often with just or other non-equal tempered tunings. Drones are a regular feature in the music of composers indebted to the chant tradition, such as Arvo Pärt, Sofia Gubaidulina, and John Tavener. The single-tones that provided the impetus for minimalism through the music of La Monte Young and many of his students qualify as drones. David First, the band Coil, the early experimental compilations of John Cale (Sun Blindness Music, Dream Interpretation, and Stainless Gamelan), Pauline Oliveros and Stuart Dempster, Alvin Lucier (Music On A Long Thin Wire), Ellen Fullman, Lawrence Chandler and Arnold Dreyblatt all make notable use of drones. The music of Italian composer Giacinto Scelsi is essentially drone-based. Shorter drones or the general concept of a continuous element are often used by many other composers. Other composers whose music is entirely based on drones include Charlemagne Palestine and Phill Niblock. The Immovable Do by Percy Grainger contains a sustained high C (heard in the upper woodwinds) that lasts for the entirety of the piece. Drone pieces also include Loren Rush's Hard Music (1970) and Folke Rabe's Was?? (1968), as well as Robert Erickson's Down at Piraeus. The avant-garde guitarist Glenn Branca also used drones extensively. French singer Camille uses a continuous B throughout her album Le_Fil. Drones continue to be characteristic of folk music. Early songs by Bob Dylan employ the effect with a retuned guitar in "Masters of War" and "Mr. Tambourine Man". The song "You Will Be My Ain True Love", written by Sting for the 2003 movie Cold Mountain and performed by Alison Krauss and Sting, uses drone bass. Drones are used widely in the blues and blues-derived genres. Jerry Lee Lewis featured drones in solos and fills. Drones were virtually absent in original rock and roll music, but gained popularity after the Beatles used drones in a