123 According to Mr. Arnold Dolmetsch, Clavichords with special strings for each note (bundfrei) were known in Bach’s time.
124 In the _Essay_ already referred to. For a discussion of Couperin’s method see Spitta, ii. 37 ff.
125 For instance, the Rondeau in B flat in Anna Magdalena’s _Noten- buch_ (No. 6) (1725) is by Couperin.
126 No doubt the friend who prepared this trap for Bach was Johann Gottfried Walther. His compositions frequently were characterised by intricacy.
127 Mozart had the same gift. When visiting St. Thomas’ School in 1789, he heard with astonishment a performance of Bach’s Motet, _ Singet dem Herrn ein neues Lied._ “At the conclusion he expressed his delight, and said, ‘Now that is something from which a man may learn.’ On being informed that Bach was Cantor to this school, and that his Motets were venerated there as reliques, he was eager to see them. No score being to be obtained, they handed him the separate parts, and it was interesting to observe his manner of reading them, holding some in his hands, some on his knees, placing some on chairs around him; seeming thoroughly lost to everything, and not rising till he had thoroughly satisfied his curiosity” (Holmes, _Life of Mozart,_ ed. Dent, p. 251).
128 There were in Bach’s time three “Clavier” instruments in use. The oldest, the Clavichord, as a rule, had two strings to every note, set in motion by a “tangent” striking them from below. Its advantage was that it permitted the tone to be regulated by the touch. For that reason, though its tone was weak, Bach preferred it. The Clavicembalo, or Harpsichord, as it is called in the text, was in general known as the “Flügel,” the strings being plucked, or flipped by a quill or metal pin, after the manner of the modern mandoline. The third instrument was the “piano e forte,” or Hammerclavier. The Clavicembalo was also built with two keyboards, like an Organ, and a pedal-board provided with strings. It was for this instrument that the so-called Organ Sonatas of Bach were written. He possessed five Clavicembali, but not a single Clavichord at the time of his death. For that reason it has been questioned whether Forkel is accurate in stating that Bach preferred the latter instrument. See Schweitzer, i. 200 ff.