In this cadence, the major third of the leading chord (the major seventh of the scale) must ascend by semitone to the octave of the key-note; and this major third of the domi nant is called the sensible note, or the leading note to the key.
105. The next chord in importance after these two, is the chord of the fourth of the key. This harmony, and that of the tonic also, succeed each other in a very agreeable man ner, (see Ex. 2. above, art. 1040 and the progression of the chord of the fourth of the scale to that of the key-note, (as sisted by accent and rhythm,) forms another kind of cadence or close of a satisfactory nature, though not so conclusive as the perfect cadence ; it is called the imperfect cadence; hence this chord is called the subdominant chord. These three chords comprehend, as Dr. Callcott observes, all the notes of the diatonic scale. In the tonic harmony are found the key-note, 3d and 5th; in the subdominant, the 4th and 6th ; and in the dominant, the 2d and 7th. " These three principal sounds," he observes, " the Tonic, Dominant, and Subdominant, are the radical parts of every scale, of the minor as well as of the majer. All melodies whatever, are derived from these sounds, and are wholly dependent on them." He adds, in another place, " the following excel lent observations of Dr. Pepusch, cannot be too often or too strongly impressed upon the mind of the student, viz. All me lodies have the perfect concords of the key they are in, (i. e. the tonic, dominant, and subdominant,)for their fundamental basses." By these observations, the student may judge of the importance of these three harmonies : the matter is, how ever, too broadly stated; for, as we have already said, every common chord in the scale is occasionally employed.
106. The next chord to these in importance, and fre quency of use, is that of the sixth or relative minor, and then the common chord of the second of the scale, which is the subdominant of the relathe minor, and is itself minor. These five harmonies are exhibited in the next example.
The student will not often find a series of so many mere common chords in inodern compositions; but Ile will find that these harmonies, somewhat differently arranged or in verted, and with some additions, which produce discords, constitute the principal part of harmonical progressions or modulations, while these continue within the key; and t‘ hen the modulation passes into another key, he will find the har monies similarly related to that new key.
107. After the sante manner, in the minor mode, the most important chord is that of the key, and the next is the do minant chord on the fifth of the key. The student must
observe that this chord has a major third, which is essential to its character of dominant, that is to say, to its making a satisfactory close on the key. Of this, the reader may soon satisfy himself, by comparing Nos. 1st and 2d in the next example.
One often hears the progression .No. 2d in the psalmody of country churches. This, and the universal practice in the early ages of music, seems to countenance the theory that the minor mode is a secondary key to its relative major, the impression of whose scale is never entirely effaced front the ear. However this may be, the fifth of the minor mode may bear a minor chord, but then it loses entirely the cha racter of a dominant chord. The next chord in point of importance is that of the subdominant ; after that the relative major, and its subdominant chord, which is that of the sixth in the minor scale. .These two last chords seem even more welcome in a modulation in the minor scale, than the rela tive minor and its subdominant in a modulation in the majot scale. These cltords are exlribited in the next example.
In the above example, the subdominant chord is minor; but it has not unfrequently a major third given it, as WC shall see afterwards.
10S. The lowest note of a chord is called its bass, and the lowest note of a common chord is called its fundamental basg ; and a common chord itself is called a tlindamental chord, in order to distinguish it from the chords that arise from its inversions ; these will be explained bye and bye.
the mean time, we shall exhibit the common chord in dif ferent positions. Besides the bass, a common chord lias two sounds, the third and fifth ; and if the octave to the bass be added, there are three solinds in the upper parts. NOW, these three upper parts may be arranged in variouspositions, which musicians distinguish into three, accortling as the oc tave, third, or fifth, hold the uppermost part. But of the four sounds, thc bass and uppermost parts being determined, the two remaining sounds may be varied in two ways, which give two forms to each of these positions, thtis plain that some of the parts must be dotibkil, e. the same note given to two or more parts, either in unison or octave. The general rttle is, that the fimclamental note should be first doubled, then the fifth, and last the third. But this rule is still subservient to that which forbids consecutive perfect concords between the same parts, and to the propriety of giving. as good a melody to all the parts as possible.