The schlüsselfidel (literally: keyed fiddle) is a partly
mechanical stringed instrument on which the strings
are sounded by a short bow and stopped by wooden
tangents rather than by the fingers. Depending on the
geographical provenance, the instrument has one or
more bourdon (drone) strings that accompany the
melody with a continuous sound. In the Middle Ages
the instrument was found primarily in Spain. It was still
described in the 16th century by Michael Praetorius and
Martin Agricola before more or less vanished. Today it is
an important element of traditional Swedish music
(Swedish: nyckelharpa).