una corda"
pedal. By this device on a grand pianoforte the whole key-board is
shifted from left to right, so that the hammers strike but _two_ wires
in each group of three, and the third wire of the set is left free to
vibrate sympathetically. Thus a very etherial, magical quality of tone
is produced, especially in the upper ranges of the instrument. In the
middle register, passages played forte or fortissimo will have a
richness comparable to the G string of a violin. The effect is
analogous to that of a viol d'amour which has, as is well known
(stretched underneath the strings, which produce the actual tone) a
set of additional strings, freely vibrating. Although this "una
corda"[220] pedal may be used in a dynamic sense to reduce, as it
were, the size of the instrument, its chief purpose is coloristic,
_i.e._, to make possible a _special quality_ of tone. This statement
is proved by directions in pianoforte literature as far back as
Beethoven, in whose Sonatas we find the dynamic marks of _f_ and _ff_
coupled with the proscribed use of the una corda pedal. In any case,
this left-foot pedal should not be abused; for, just because the tone
quality produced thereby is so beautiful and characteristic, it soon
becomes, if constantly employed, rather cloying. The dynamic gradation
of tone is primarily a matter for the control of the fingers, _i.e._,
the touch. The damper pedal is for sonority and color; the una corda
for special shades, and all three factors--touch and the two
pedals--are combined in pianistic effects which only a trained
technique and artistic judgment can regulate.[221]

[Footnote 220: The term dates from the period when this pedal
controlled three shifts: una corda, due corde and tre corde; the
hammer striking respectively one, two or three strings. The whole
mechanism is well implied in the German word _Verschiebung_, _i.e._,
the shoving along--so frequent in Schumann's works, _e.g._, the middle
part of his _Vogel als Prophet_ from the _Waldscenen_, op. 82, No. 7.]

[Footnote 221: American pianofortes also have a middle pedal called
the "sustaining pedal," by which tones in the lower register may be
prolonged. It has not proved to be of great value, though there are
occasional passages, _e.g._, the closing measures of the second
movement of Cesar Franck's _Violin Sonata_, where it may be
effectively employed.]

Even a slight analysis of Chopin's style proves that it is based upon
logical inferences