OF NATVRAL TRANSITIONS BY THESE CHORIV.
136. HAviNG exhibited pretty fully the mutual connexions of the tonic, dominant, and subdominant harmonies within the key, we shall now proceed to give some specimens pas sing into the nearest related keys. These are from the ma jor principal key, to the fifth and to the fourth of the key both in the major mode, to the sixth of the key minor mode, called the relative minor, to the second of the key, and to the third of the key, both in the minor mode : From the principal minor key, again, to the fifth and fourth both in the minor, to the third of the key major mode, or relative major, and to the sixth and seventh both in the major. We mean not here to treat the subject of changes in modulation fully,—which requires the knowledge of some other chords not yet treated of; but merely to show how we may pass agreeably from the harmonies of one key to thosr, of another nearly related to it.
137. The most natural and most practised of all changes of key, is to the fifth: and from the tonic harmony to the dominant leading to that new key, we pass in the most na tural manner ; No. 1, a, b. We have already remarked, what indeed is very obvious, that in this change the tonic harmony of the principal key is the subdominant common chord on the fourth of the new key. All the examples, therefore, which We have given of the passage from the sub dominant harmony to the dominant, are applicable to this change ; we shall therefore leave this application to the in dustry of the reader, without more examples, which would be mere repetition.
We might pass from the subdominant harmony of the principal to the dominant of this new key. To go from the common chord on the 4th of the key to this new dominant 7th, however, as in -,No. 2, is not very good, because of the false relation crossways, between the note quitted by the bass and the major third of the dominant chord. In general, it is to be observed, that when a note is first heard natural in one chord, and in the next chord the same note is sharpened or flattened, this chromatic change ought to take place in the same part, and the octave of the natural note in the first chord ought not to be heard in another part, because of the bad effect of the cross false relation of octave. If, for in
stance, we follow the common chord of F, with the chord of 7th to D, with minor third, and then change the third chro matically as at b, the harshness is quite removed. Or we may take the subdominant seventh on the second oldie scale immediately-, and then change that chord chromatically to a dominant, as at c. The first inversion of this progression, changing the subdominant 5th and 6th into the dominant small fifth and sixth, goes very agreeably, and is frequently met with, as in No. 3. The second and third inversions, Nos. 4 and 5, are also very good. No. 6, in which the bass leaps to the dominant 7th, is less agreeable than the others.
In the minor mode, two parts will move chromatically. No.7, a ; or the subdominant harmony- may' be taken major, as at b.
Here we may remark, in passing, that a stroke after a figure, as in these examples, denotes the continuance of tbe same note in the upper part, even when the movement of the bass changes the interval.
138. To go from the common chord of the principal key to the dominant, leading to the fourth of the key, is only adding a minor seventh to that common chord. The octave succeeded by the minor seventh, is an agreeable and much practised appoggiatura, No. 1.
In the major mode, all the derived successions are good, Nos. 2-12. Monsieur Choron observes, that the second without preparation, Nos. 4, 8, 12, is considered as a changed note, that is, that one part takes the place of another, which ts always allowed, especially when it is necessary, in order to satisfy some condition, as in fug-ues, canons, and tional counterpoints. The four last successions, lie observes, 6 are surprises in harmony; for the first chord carrying 4, seems to indicate a close, (in the primary key,) as in No. 13; but the chord of seventh, or its derivatives, succeeding, carries the modulation to the fourth of the key. Of these four suc cessions, No. 9 is the worst. The three others are of good effect.