(It., from capo: ‘head’, tasto: ‘tie or fret’; Fr. barre; Ger. Capotaster).
(1) Originally this term denoted the nut (see Nut (i)) of a fretted instrument such as the lute or guitar; it is now generally used to describe a device to shorten the string length, thus facilitating upward transposition without altered fingering. (It is also the term used in Italian writings to describe the stopping of general strings at once by one finger; see Barré (i).) The construction of the capo tasto varies according to the instrument for which it is intended, but it comprises essentially a rigid bar covered with felt, leather or cork, together with some means of holding it pressed firmly against the fingerboard. This bar keeps the strings in contact with the required fret and may take the form of a length of gut tightened round the neck by a peg. The bar may now be held by a metal spring or a piece of elastic. On the English guitar the capo tasto was attached through holes in the neck by a small carriage bolt tightened by a wing nut. The term was first employed by G.B. Doni in his Annotazioni of 1640.
(2) Later the term was used to describe the metal bar which acted as a nut by exerting a downward pressure on the treble strings of pianos. The device was invented in 1843 by Antoine-Jean Denis Bord of Paris.
IAN HARWOOD