The baryton is a bowed string instrument which shares some characteristics with instruments of the viol family, distinguished by an extra set of plucked strings. It was in regular use in Europe up until the end of the 18th century. The baryton differs from the bass viol in having an additional set of wire strings. These perform two functions: they vibrate sympathetically with the bowed strings, enriching the tone, and they can also be plucked by the left thumb of the performer, creating a contrasting tonal quality. As can be seen in the illustration, the bowed strings are placed on the right, where they can be easily fingered by the player's left hand. The plucked strings are on the left; they were reachable by the player's thumb from the rear, where the back of the instrument's neck was left open. Of the repertoire for this instrument, the best known works are the 175 compositions written by Joseph Haydn for his patron, Prince Nikolaus Esterházy, who enjoyed playing this instrument.