Clavichord and Virginal.
The clavichord, the earliest progenitor of the piano, originated in an instrument in which the tangent which struck a given string also acted as a bridge to mark off the length of the vibrating portion and therefore to determine the note produced. It is remarkable that (p. 115) this type of instrument remained in use until the time of Sebastian Bach, when the principle of “one tangent one string” replaced the more ancient system.
Of the clavichord Mr Dolmetsch (p. 433) writes that its tone is comparable, as regards colour and power, “rather to the humming of bees than to the most delicate among instruments. But it possesses
a soul . . . for under the fingers of some gifted player it reflects every shade of” his “feelings like a faithful mirror. Its tone is alive, its notes can be swelled or made to quiver just like a voice swayed by emotion. It can even command those slight variations in pitch which in all sensitive instruments are so helpful to expression.”
The best known among the group of instruments to which the clavichord belongs are the spinet and the harpsichord. I think that Browning’s musician who “played toccatas stately at the clavichord” must have performed on one of the last-named instruments. In the spinet and the harpsichord the strings are plucked, and therefore sounded, by small points made of leather or of quill which are under the control of the keyboard.
Mr Galpin (who is always interesting on evolution) points out that the progenitor of the spinet is the plucked psaltery, whereas the piano forte (the earliest form of which appeared about 1709) is a descendant of the dulcimer in which the strings were struck.