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LETTER VIII.
ON THE FORMATION OF CHORDS.
You will already have discovered, Miss, that, among intervals, many sound agreeably, and many others very much the reverse. For this reason, intervals are divided into such as are consonant (or agreeable to the ear), and dissonant (or disagreeable to the ear).
Consonant intervals are:
(a.) The perfect unison;
(b.) The major and minor third;
(c.) The perfect fifth;
(d.) The major and minor sixth;
(e.) The perfect octave;
(f.) The major and minor tenth.
All others are dissonant.
Consonant intervals are still further divided into perfect and imperfect.
The perfect are: the perfect fifth and perfect octave.
The imperfect are: the major and minor third, and the major and minor sixth.
Concords are distinguished from discords, among other properties, by the latter requiring
