Forkel's meaning can be made clear in the following manner: place the thumb and fingers of either hand upon the notes C D E F G of the pianoforte so that the three middle fingers lie more or less flat upon the keys; then draw back the three middle fingers until they form an arch having their tips approximately in a straight line with the tips of the thumb and little finger upon the keys.
It must be remembered that Forkel is speaking of the Clavier and not of the Pianoforte.
The Harpsichord, as its name implies, was an instrument whose strings were plucked by a plectrum. Bach preferred the older Clavier, or Clavichord, which could be regulated, as the other could not, by nicety of touch. See note, p. 68, infra.
Schweitzer (i. 208) points out that Bach's touch was modern, in that he realised that “singing tone” depends not only upon the manner in which the keys are struck, but, to a great extent, on the regulation of their ascent.
Of Handel's touch, Burney writes (quoted by Rockstro, p. 349): “His touch was so smooth, and the tone of the instrument so much cherished, that his fingers seemed to grow to the keys. They were so curved and compact when he played, that no motion, and scarcely the fingers themselves, could be discovered.”
At the beginning of the seventeenth century, as Spitta points out (ii. 34), the art of fingering had not developed. Speaking generally, neither thumb nor little finger was employed. It was not until the beginning of the eighteenth century that a scientific method emerged, a development rendered necessary by the advance in the modes of musical expression. C. P. E. Bach, quoted by Schweitzer (i. 206), puts this concisely: “My late father told me that in his youth he had heard great men who never used the thumb except when it was necessary to make big stretches. But he lived in an epoch when there came about gradually a most remarkable change in musical taste, and therefore found it necessary to work out for himself a much more thorough use of the fingers, and especially of the thumb, which, besides performing other good services, is quite indispensable in the difficult keys, where it must be used as nature intends.”
According to Mr. Arnold Dolmetsch, Clavichords with special strings for each note (bundfrei) were known in Bach's time.
In the Essay already referred to. For a discussion of Couperin's method see Spitta, ii. 37 ff.
For instance, the Rondeau in B flat in Anna Magdalena's Noten- buch (No. 6) (1725) is by Couperin.
No doubt the friend who prepared this trap for Bach was Johann Gottfried Walther. His compositions frequently were characterised by intricacy.