The early experiments in tempering must have led to curious results—thus the major-thirds were flattened; and yet only when three major-thirds are sharpened (CE, E G♯, G♯ (A♭) C) do they reach a purely tuned octave. Bach mastered the problem for himself. He tuned his own harpsichord and clavichord, making the major-thirds rather sharp; and he must have flattened the fifths as we do. His son Emanuel speaks of his testing the fifths by tuning their octave below, and making this a fourth below the starting point. What he did was the result of practical experiment, for he would have nothing to do with mathematical theory. He always quilled his harpsichord himself; and he made a point of practising the clavichord, since the expression possible on this instrument made the ear keener and more sensitive to the possibility of effect on the more inexpressive harpsichord.
Spitta considers that Bach’s genius in a way foresaw the advent of a more perfect instrument than either the clavichord or harpsichord—an instrument which should combine the expression of the first with the power of the latter, and at the same time approach the organ in possibilities of legato and sustained sounds. Such an instrument is the modern pianoforte.
The Lute-harpsichord
In 1740 Bach planned a lute-harpsichord, and got Zacharias Hildebrand, an organ-builder, to make it under his direction. It had gut strings, two to each key, and a set of octave metal strings. It had also cloth dampers, which made the instrument sound something like a real lute; and when these were raised, it sounded like a theorbo—it was in size shorter than an ordinary harpsichord (Adlung Mus. Mech. II., p. 139).
Although Bach was concertmeister, or leader of the orchestra at Cöthen, it is not to be supposed that he had any extraordinary facility on the violin. Quantz, in “Versuch einer Anweisung, etc.,” rightly considers that for such a post, at any rate in those days, it was more necessary that the holder should be a good all-round musician with sufficient facility to execute the ordinary orchestral music, than that he should be a “virtuoso”—and not every virtuoso makes a good leader.
Knowledge of stringed instruments
His knowledge of the construction of stringed instruments was sufficient for him to invent a new one while he was at Cöthen, in order to meet the demands made on the performer by his own music. This instrument, which he called the viola pomposa, was something between the viola and violoncello. It was played like a violin, and had five strings tuned to the four strings of the violoncello, with the addition of E above the first string. This additional string makes the performance of his sonatas for violoncello comparatively easy. Thus in the sixth violoncello sonata, which is expressly written for five strings, in the third bar of the saraband the chords
