A marking of col legno
, or more precisely col legno battuto
for "hit with the wood"), is an instruction in written music to strike the string of a bowed string instrument
with the stick of the bow, rather than by drawing the hair of the bow across the strings. This results in a quiet but eerie percussive sound. The string section plays col legno
in the "Dream of Witches' Sabbath", the fifth and last movement of Berlioz
's Symphonie Fantastique
, as well as in "Mars, the Bringer of War", the first movement of Holst
's The Planets
, and the first movement of Mahler
's Symphony No. 2
. The percussive sound of col legno battuto
has a clear pitch element determined by the distance of the bow from the bridge at the point of contact. As a group of players will never strike the string in exactly the same place, the sound of a section of violins playing col legno battuto
is dramatically different from the sound of a single violin doing so.
The wood of the bow can also be drawn across the string — a technique called col legno tratto ("drawn with the wood"). This is much less common, and the plain marking col legno is invariably interpreted to mean battuto rather than tratto. The sound produced by col legno tratto is very quiet, with an overlay of white noise, but the pitch of the stopped note can be clearly heard.
Some string players object to col legno playing as it can damage the bow; many players have a cheaper bow which they use for col legno passages, or for pieces which require extended passages of col legno. Some players tap the strings with pencils instead of bows, producing a further percussive, lighter sound more common in 20th century music.