Leonardo's designs. It uses several friction wheels instead of a friction belt to vibrate the strings, and requires two people to play it: one to turn the crank to put the rosined wheels in motion, and the other to work the keys. Georg Gandi, an organist in Ilmenau, constructed a similar instrument with some improvements in 1709 and called it the piano viol. In 1741, two inventors – Le Voir in Paris and Hohlfeld in Berlin – independently constructed versions of a bowed piano, similar to Heyden's design. In 1754, a horsehair covering was added to the wheels of the bowed piano, which was termed the viola da gamba piano. Other instrument makers continued to improve the design through the remainder of the 18th and into the early 19th centuries, though it never became widespread or common. These instruments remained primarily museum curiosities until a few modern instrument builders began to take an interest in creating reconstructions of the Geigenwerk, but calling them viola organista. Akio Obuchi built several instruments as early as 1993. In 2013, Polish musician Sławomir Zubrzycki completed the construction of another modern replica of the Geigenwerk called viola organista and played it in performance at the Academy of Music in Kraków. Zubrzycki's instrument contains four bow-wheels (spun by a foot-pedal operated by the player), 49 keys, and a range extending from F1 to F5. In 2015, the musician Björk included this instrument – also played by Sławomir Zubrzycki – in a recording of the song "Black Lake" for the album Vulnicura Strings. Another modern instrument similar in concept, if not design, is the wheelharp, created by Jon Jones and Mitchell Manger in 2013, and debuted at the NAMM Show that year, in Anaheim, California. References Further reading Carolyn W. Simons, "Sostenente piano", and Emanuel Winternitz and Laurence Libin, "Leonardo da Vinci," Grove Music Online ed. L. Macy (Accessed April 2, 2005 at www.grovemusic.com), (subscription access) "Sostenente piano", The New Harvard Dictionary of Music, ed. Don Randel. Cambridge, Massachusetts, Harvard University Press, 1986. External links Akio Obuchi's reconstruction as used in Genoa Viola organista made by Sławomir Zubrzycki Bowed string instruments Experimental musical instruments Italian inventions Keyboard instruments Leonardo da Vinci projects