133. This diatonic sequence of sevenths is frequently met with both in ancient and modern authors; of which a good many examples are quoted by Mr. Shield, in his introdauc tion to Harmony, p. 79. The descending sequence of sevenths and sixths, which is also a rery frequent passage, is derived from it; which the reader will easily see by com paring the example of it in No. 1, in this article, with the example No. 2, c, in the last: for the sequence of and 6 is no other than the notes in the upper line of that example; the lowest notes being removed an octave lower. It appears, therefore, that the cltord of the sixth, which follows on the 6 same bass, is the 4, second inversion of the chord of seventh 3 to the fifth below. But as this inversion of the 7th is not agreeable, except that of the dominant seventh, the 4th is omitted, and the chord appears as a 6th. Compare what is said of the examples, Art. 128, 4, a, b. Hence this sequence is usually written in three parts. By writing the part next the bass in Art. 132, c, over the bass of this sequence, we 6 have four parts, and the 4 complete in every second chord, 3 No. 2. But the reader will hardly think this an imiirove latent : No. 1. is pleasing and attractive; No. 2. barely tolera ble. Mr. Kollmann, in his thorough bass, gives this prop es sion as in No. 3; the effect of which is not very bad: though certainly very inferior to that in No. 1.
134. In like manner it is not unusual, as Dr. Callcott observes, to follow the chord of the fifth and sixth, with the common chord, instead of the chord of seventh: the example we copy from his Musical Grammar.
is the alternation of the first and third derivatives on a bass descending by degrees of the scale, as in No. 1. This
ple is also copied from Mr. Kollmann's thorough bass: but that the reader may not be misled by this or by that in Article 133. 3, lle must be told, that though these examples begin with the discord, yet that note is always prepared in the preceding chord. In this progression also, the fifth in the 6 chord of 6 and the 4th in the 4 are frequently omitted, so 5 2 that every second chord becomes a chord of sixth, as No. 2. In the minor mode, this progression goes very agreeably, 6 .
on account of the resolution of the subdominant 5 into the :3i(6 4 of the dominant, No. 3.
We shall conclude these examples by observing, that all these chords of the seventh, and their derivatives, which re quire preparation of the discord, (that is, all except the domi nant seventh and its derivatives,) may be very well under stood or explained as suspensions, which the reader will easily see when we come to treat of that subject. It is as suspensions that these chords are explained by Mon. Charon, and by 'Mon. Cate). The latter considers as chords properly so called, only such as do not require preparation. These he calls natural chords ; and harmony, consisting of such, lle calls natural harmony. Artificial harmony is drawn from natural by the suspension of one or more parts prolonged on the time of the succeeding chords. We reckon it, however, a very great advantage to our readers to present the same sub ject in different points of view. And these chords of the seventh with their derivatives, follow so naturally the ana logy of the dominant seventh, (except in the circumstance of requiring preparation,) that an individual acquaintance with them is caily acquired, and well repays the cost of the acquisition.