It's not a string instrument, but Georg Philip Telemann composed 12 fantasias for it as well as six Sonatas sans basse for two of them.
A set of six baroque sonatas for this instrument contains various character pieces interspersed or "medleyed" among larger pieces named L'Henriette and La Chauvet.  Michel Blavet was an early virtuoso on this instrument, which is the only one that does not play at the opening of the Fifth Brandenburg concerto, instead entering after the end of the first phrase. Jacques-Martin Hotteterre wrote one of the earliest treatises on playing this instrument in its revised three-section design. To let it play E-flat, a second (*) key was added to it by Johann-Joachim Quantz. It's not a string instrument, but Georg Philip Telemann composed 12 fantasias for it as well as six Sonatas sans basse for two of them. During the baroque period, it was sometimes known simply as the traverso or traversiere.  It was the primary instrument of the composer who provided JS Bach with the theme for The Musical Offering. For 10 points, name this woodwind instrument played by Frederick the Great, which is held transversely unlike its relative the recorder.
A set of six baroque sonatas for this instrument contains various character pieces interspersed or "medleyed" among larger pieces named L'Henriette and La Chauvet.  
flute