A Dictionary of Music and Musicians/Tangent
TANGENT, in a clavichord, is a thick pin of brass wire an inch or more high, flattened out towards the top into a head one-eighth of an inch or so in diameter. It is inserted in the back end of the key, and being pushed up so as to strike the pair of strings above it, forms at once a hammer for them and a temporary bridge, from which they vibrate up to the soundboard bridge. In the clavichord no other means beyond this very primitive contrivance is used for producing the tone, which is in consequence very feeble, although sweet. The common damper to all the strings, a strip of cloth interwoven behind the row of tangents, has the tendency to increase this characteristic of feebleness, by permitting no sympathetic reinforcement.
In all clavichords made anterior to about 1725 there was a fretted (or gebunden) system, by which the keys that struck, what from analogy with other stringed instruments may be called open strings, were in each octave F, G, A, B♭, C, D, E♭. With the exception of A and D (which were always independent), the semitones were obtained by the tangents of the neighbouring keys, which fretted or stopped the open strings at shorter distance, and produced F♯, G♯, B♮, C♯, and E♮. Owing to this contrivance it was not possible, for example, to sound F and F♯ together by putting down the two contiguous keys; since the F♯ alone would then sound. We have reason to believe that the independence of A and D is as old as the chromatic keyboard itself, which we know for certain was in use in 1426. Old authorities may be quoted for the fretting of more tangents than one; and Adlung, who died in 1762, speaks of another fretted division which left E♮ and B independent, an evident recognition of the natural major scale which proves the late introduction of this system.
The tangent acts upon the strings in the same way that the bridging or fretting does upon the simple monochord, sharpening the measured distances which theory demands by adding tension. Pressing the key too much therefore makes the note sound intolerably out of tune. An unskilful player would naturally err in this direction, and Emanuel Bach cautions against it. In his famous essay[1] on playing he describes an effect special to the tangent, unattainable by either jack or hammer, viz. the Beben or Bebung, which was a tremolo or vibrato obtained by a tremulous pressure upon the key with the fleshy end of the finger. It was marked with a line and dots like the modern mezzo staccato, but being upon a single note, was, of course, entirely different.
The article Clavichord is to be corrected by the foregoing observations.
- ↑ 'Versuch über die wahre Art Klavier zu spielen,' 1753, another edition, 1780, and republished by Schelling, 1857.