Rhino Entertainment Company / YouTube On March 19, 1968, an amateur recording engineer set up his gear at Le Hibou, a coffeehouse in Ottawa, Canada. He taped two sets by Joni Mitchell, who was 24 at the time. That recording engineer, a Mitchell fan, was none other than Jimi Hendrix, who'd played his own gigs a few blocks away. Hendrix's tapes were stolen, only to surface five decades later and get returned to Mitchell. His crystalline recording of "The Dawntreader" reveals a spellbinding performance — just Mitchell and her guitar — similar to what the world would hear just days later when her first album was released. One of Mitchell's most atmospheric songs, "The Dawntreader" unfolds in a dreamlike nautical setting of sunken treasure, mermaids and mysterious "songs that the rigging makes." The unconventional guitar tunings, her self-described "chords of inquiry," offer an orchestra's worth of color and texture in a song that, 53 years on, still possesses a singular haunting power. This track is part of Mitchell's ongoing archival project, and will be issued Oct. 29 on