MUSI C. 
a fingle 6 only, which occafionally, as modulation re¬ 
quires, has the ufual marks annexed to it, thus ft, Q ,6^. 
According to the obfervation as above, a fixth in thorough 
bals always implies the common chord of a third below 
it; and hence wemayeafily conclude, that there mull; be 
as many different fpecies of fixth chords as there are com¬ 
mon chords. See Ex. 26. 
There are various ways of accompanying fixes : 1. with 
a third and eighth ; 2. with a third and a double fixth; 
3. with a double third ; and, 4. with a third only, or a uni- 
i'on doubled. See Ex. 27. The accompaniment with the 
eighth, like the common chord, has three different pofi- 
tions ; for either the fixth, third, or eighth, may be placed 
at the top, in the middle, or at the bottom. That fitua- 
tion where the fixth is uppermoft is the moll pleafing, and 
that with the eighth at top the lead fo. 
The fixes in the chord of the fixth are either major, 
minor, orextreme fharp; and the thirds, major and minor; 
and therefore may be divided into the following different 
claffes : 1. The minor fixth accompanied with a minor 
third. 2. The major fixth accompanied with a major 
third. 3. The major fixth accompanied with a minor 
third. 4. The minor fixth accompanied with a major 
third. 5. The extreme fharp fixth accompanied with a 
major third. 
The minor fixth with a minor third has its place on 
every major third ; that is, on the third, fixth, and feventh, 
of the major mode, and on the prime, fecond, fifth, and 
afcending fixth and feventh, of the minor. Its original 
harmony is that of the major triad, or fundamental com¬ 
mon chord. The major fixth with a major third may be 
applied to any note that is a third to the minor triad; 
that is, on the key-note, the fourth and fifth in the major 
mode; and on the third, the natural or defcending feventh 
and fixth of the minor. Its fundamental harmony is that 
of the minor triad. The major fixth with a minor third 
has its place only on the fecond of the major, and on the 
fourth of the minor mode. Its original is the imperfeft 
triad. The minor fixth with a major third (the latter 
being the leading notes in the minor mode) is introduced 
only on the fifth of that mode, and on that but fpar- 
ingly. Its original is the extreme fnarp triad. The ex- 
treme-fharp fixth with a major third is introduced only 
on the defcending fixth of the minor mode, and always 
afcends to the next note above it. This chord properly 
arifes from a triad that is compofed of an imperfect fifth 
and extreme-flat third. The different manner of accom¬ 
panying fixes is exhibited in one view at Ex. 28. 
Of fitccejfive Fifths and Sixes, marked thus, 5 6. 
This fignature implies two different chords ftruck to 
the fame bafs note; the 5 implies a common, and the 6 
a fixth chord. In competitions in four parts, either the 
5th, 6th, or 3d, occafionally may be doubled, as at A. 
Ex. 29. but in three parts, the 3d only is added, which 
is the eafieft, and, in quick time, the moll proper, as at B. 
Of fucceffive Sires and Fifths, marked thus, 6 5. 
The manner of accompanying the chord fignified by 
tliefe figures, is much the fame as that of 5 6, the former 
being only the reverfe of the latter ; and therefore the fuc- 
ceeding fifth is confidered as a palling note, and mull de- 
feend to the next note below it; but the fixth may be 
accompanied in all its different ways, as exemplified 
above. See Ex. 30. 
Of the Chords of the Sixth and Fourth accompanied by the 
Eighth; figured thus, 4. 
As the chord of the fixth arofe from the firft inverfion 
of the triad, called the common chord, by the fubftitution 
of the third of the latter for the balls of the former ; fo in 
the fame manner that of the fixth and fourth arifes from 
the fecond inverfion of the triad, by fubftituting the fifth 
of the latter for its bafs note. Therefore, whenever we 
find a bafs note figured with %, it always implies a triad 
331 
to the fourth above or fifth below it. The common chord 
and its two inverfions are fliown at Ex. 31. 
The following are all the different fpecies of the chord 
of the 5 that are ufed in harmony : 
1. That which arifes from the major triad, confifls of 
a perfeft fourth, a major fixth, with its prime or oftave; 
and may be introduced on the key-note, but more par¬ 
ticularly on the fifth of the major mode, where it generally 
implies a cadence. 
2. The fixth and fourth that proceeds from the minor 
triad, confifls of a perfedt fourth and minor fixth, and 
is properly applied to the minor mode in the fame 
manner. 
3. The chord of the fixth and fourth that arifes from 
the imperfect triad, confifls of an extreme-fharp fourth 
and a major fixth : it is introduced on the fourth of the 
major and the defcending fixth of the minor mode. This 
fourth frequently refolves into a third on the fame bafs 
note when it is accompanied by a 6 doubled, but more 
frequently in three parts by a fingle 6 only. 
4. That which proceeds from the extrerne-fharp triad, 
confifls of an extreme-flat fourth and a minor fixth; and 
is applied only on the feventh of the minor mode, where 
it is ufed by way of tranfition in the accompaniment of 
three parts only. 
Ex. 32. is calculated for pradtifing the fixth and fourth, 
as ufed on cadence-notes on the fifth of the mode, by 
way of a lhort prelude to any key. 
Of the Chord of the Seventh. 
The chord of the feventh arifes from the addition of a 
third to its common chord, and therefore is compounded 
of three thirds. According to the different fpecies of in¬ 
tervals contained in the major and minor modes, it may 
be divided into all different kinds exprefied on Plate V. 
Ex. 1. A, B, C, &c. 
1. The minor feventh accompanied by a major third 
and perfect fifth, is applied on the fifth of either mode, 
the bafs rifing a fourth or falling a fifth, and is confidered 
the principal harmony next to that of the fundamental 
chord of the mode, and decides the key, and whether it is 
major or minor. See Ex. 2. 
2. The minor feventh with a minor third and perfedt 
fifth, is applied on the fecond, third, and fixth, of the 
major, and on the prime, fourth, and fifth, of the minor, 
mode. 
3. The minor feventh with a major third and perfedt 
fifth, is introduced on the prime and fourth of the major, 
and on the third and fixth of the minor, mode. 
4. The accidental major feventh with a minor third 
and perfedl fifth, is ufed only on the prime of the minor 
mode. 
5. The major feventh with a major third and extrerne- 
fharp fifth, is introduced only on the third of the minor 
mode. 
6. The minor feventh with a minor third and imperfedfc 
fifth, is applied on the feventh of the major, and on the 
fecond and afcending fixth of the minor mode. 
7. The extreme-flat feventh with a minor third and 
imperfedl fifth, is ufed only on the afcending feventh of 
the minor mode, and conl'equently its bafs note always 
requires a fiiarp mark. 
Thefe are all the different fevenths ufed in thorough 
bafs. The two laft, marked H and I, are ufelefs in their 
fundamental pofition, but are introduced among the reft, 
as being the foundation of the following chords uled in 
harmony, arifing from the inverfion thereof. See Ex. 3. 
The feventh, like all difeords in general, mull refolve 
in the fame part of the chord where it happens to be 
placed, by defcending one degree to the next individual; 
which, according to the different progreflions of the bafs, 
may be either a third, fourth, fifth, fixth, feventh, or 
eighth. It refolves, 1. By a third, when the bafs riles a 
fourth or falls a fifth, as in Ex. 4. where at A, it refolves 
in the upper part, at JB in the middle, and at C in the 
lower 
