Editing Double stop (section)

===Bach bow===
The "Bach bow" with its arched back uses a system of levers to slacken or tighten bow hair immediately while playing so as to (according to its advocates) facilitate the performance of polyphonic music. Such a bow was conceived early in the 20th century by [[Arnold Schering]] and Albert Schweitzer and constructed by Rolf Schröder in 1933.<ref>David D. Boydon (2001), ''[[New Grove Dictionary of Music]]'', "Bow", ed. [[Stanley Sadie]].</ref> A similar device called the "Vega bow" was built in 1954 under the sponsorship of the violinist [[Emil Telmányi]].<ref>''Oxford Dictionary of Music'', "Telmányi", Oxford University Press.</ref> Neither of these bows bears any particular relation to historical [[baroque music|Baroque]] bows and neither has ever been widely employed. In 1990, German cellist [[Michael Bach (musician)|Michael Bach]] invented a curved bow for cello, violin, viola and bass.<ref>[[Michael Bach (musician)|Michael Bach]]: ''Fingerboards & Overtones, Pictures, Basics and Model for a New Way of Cello Playing'', Edition Spangenberg, Munich 1991, {{ISBN|3-89409-063-4}}.</ref> He named it "BACH.Bogen" (BACH.Bow) after his own name.