[Listen.]

In the first tetrachord B was flat, in the third natural; in the fourth, F was sharp. As to the use made of this scale, little or nothing is known.

Guido’s Scale.—The other attempt, usually attributed to Guido, a contemporary of Hucbald, resulted in the Hexachord Scale (six-note scale). This scale was formed by adding a whole tone above and below the Hucbald tetrachord, thus: G, A, B, C, D, E. To complete the series of Hexachord Scales, another sound was added, namely: the G below the A on which the Greek scales and their derivatives, the Church scales, began. The first seven letters of the Roman alphabet were used to name the sounds already in use, hence to indicate this sound the Greek letter, Gamma, was adopted. At the same time the syllables ut—re—mi—fa—sol—la were used to name the sounds of every hexachord (precisely as the movable Do is used now); hence this lowest sound was called Gamma-ut, corrupted into Gamut. The sounds in the series were indicated by placing after the letter the syllables that indicated its position in all the hexachords in which it was found, thus:

G A B—C D E
C D E—F G A

1. Gamma—ut. 2. A—re. 3. B—mi. 4. C—Fa—ut, because C is fa in the first, and ut in the second hexachord. Consequently, to a mediæval musician, C—fa—ut meant what we would call C, second space bass clef.

The following table gives all the Hexachord Scales with the names of the sounds. It is of interest because this system of nomenclature persisted long after the one which gave rise to it was obsolete.

The Hexachords in which the B was flat were called Soft (Mollis); those in which B was natural, Hard (Dura); the term mollis has been retained in the French word Bemol, a flat, and in the German name for a minor key, Moll. The word dura (hard) is also retained in the German as a name for the major key Dur. When the letters were used as a means of notation, the sound B-flat was indicated by the old form of the letter b, which has been retained as the sign for a flat. This was called B rotundum (round B); when B natural was wanted, a stroke was put on the right side of the ♭, called B quadratum (squared B), the sign to this day for a natural.