The Gregorian Plain Chant is governed by two clefs, the Ut clef, and the Fa clef; which correspond to the tenor and base clefs in modern music.
The use of these clefs is to point out the progression of tones and semi-tones, and to determine the key or tone of the chant, which is commonly contained in a staff of four lines; but as it frequently happens that the music exceeds that compass, the clefs necessarily change their places on the staff to give a greater scope to the chant; therefore on whatsoever line of the staff the Ut clef is placed, that line is called Ut, the rest of the notes following in the same progression. The same rule applies to the Fa clef.
The bars which nearly cross the staff, are used to separate the notes sung to each word; the bars which entirely cross the staff are used over some period in the reading; the double bar is placed at the end of a strain or verse.
The diamond shaped note is half the length of the square note; the notes with the tails are double the length, or equal in time to two square notes, (but these must not be mistaken for notes which, having tails, are only meant to tie them to other notes higher or lower on the staff.) A dot placed after a note increases its value one half. Sharps are not used in plain chant. Flats and naturals have the same power as in modern music.
In the following example, the bars are used to divide the melody into equal portions.
Stabat mater — in G major.
The same in modern notation.
Since the decease of Mr. Hughes, the punches, matrixes, &c. of the above founts of music types (and that mentioned at page 490) have been purchased by Mr. C. Hancock, of Middle Row, Holborn, by whom they have been considerably improved, and by whom the profession are supplied.