Textbook of Gregorian Chant (1930) - MusicaSacra

Part One.
The comma or virgula (3) indicates a very rapid breath taken
off the value of the preceding note :
The quarter bar and the half bar mark secondary pauses taken
in a similar manner off the value of the note before:
The whole bar indicates a silence lasting one whole beat, or the
value of a note:
The bars in Gregorian music do not indicate time-divisions.
The part played by each of these signs in the punctuation of a
musical phrase will be noted later on.
Lesson II.
The Diatonic Scale. Tones and Semitones. The Flat.
The Natural. The Chromatic Scale.
In defining Gregorian chant we called it diatonic music. In
order to understand the first part of this definition it must be made
clear that.the scale or diatonic scale is a progression of seven
sounds following one another in a natural gradation by tones and
semitones. There are only two semitones in the diatonic scale.
They occur between mi and fa and again between si and do.
All the other notes are at intervals of a tone.
I ; m
• tone lone x /2 tone tone tone tone ]/2 tone
A single exception is allowed in the chant. It consists in
transposing the semitone between si and do to place it between
la and si. This operation is carried out by means of B flat:
S r-ti——
a —~
tone tone x /2 tone tone tone l /z tone tone