They swirled around Sprague Hall as local guitar god Benjamin Verdery performed a new piece called "Atlantis (2008)."

It was an original piece written for two instruments -- classical guitar, and a space-age-sounding instrument called the Theremin.

Elizabeth Brown of Brooklyn plays the Theremin, which a Soviet cellist invented in 1919. Brown wrote the new "Atlantis" piece. She and Verdery performed it as the finale of a Verdery guitar concert Wednesday night.

The guitar part was written to be played with a slide, and with the guitar tuned to open D-minor (a key the late blues guitarist Albert Collins preferred). Brown wrote it that way because she had been playing a guitar so much that her fingers hurt, so she preferred using the slide.

Verdery's amp was set to give his guitar an "underwater" sound.

The Theremin part adds a radio wave melody, sort of like what Kate Bush might sound like if she were an electronic gizmo.

Brown and Verdery -- and the audience -- liked the piece so much, that the duo played it a second time as an encore. It still sounded fresh, all the way through.

Click on the above video to watch Brown describe and demonstrate, after the performance, how the Theremin works. The instrument drew post-concert curiosity seekers.