| major | intervals | invert | to | minor | intervals |
| minor | " | " | " | major | " |
| perfect | " | " | " | perfect | " |
| diminished | " | " | " | augmented | " |
| augmented | " | " | " | diminished | " |
By the use of the above table and rule 8, all inversions may be determined. Examples:—
| major 2nd | inverts to | minor 7th |
| major 6th | " " | minor 3rd |
| perf. prime | " " | perf. 8th |
| perf. 4th | " " | perf. 5th |
| aug. 4th | " " | dim. 5th |
| dim. 7th | " " | aug. 2nd |
| etc. | etc. |
The prime is also called an unison, but in speaking of intervals, it should always be called a prime. Correctly speaking, a perfect prime is not an interval, but in the theory of music it is so called. There is good reason for making this error, but none for calling a diminished prime a diminished unison. Notice that the diminished second as well as the perfect prime is an unison.
Intervals are considered both harmonically and melodically, or in other words, both when sounded together or separately. In either case, the lower note is the one from which to determine the interval.
CHORD CONSTRUCTION.
A chord is a combination of two or more tones sounded simultaneously. All chords are constructed in thirds. The fundamental tone of a chord is the tone on which the chord is constructed.
A chord of three tones is a triad which consists of a fundamental together with its third and its fifth. Triads are divided into two classes, independent and dependent. The independent triads have no dissonant intervals and may end a composition. The dependent chords have one or more dissonant intervals and are "restless" chords and demand another chord to follow. The progression of a dependent chord to an independent chord, thereby obtaining a restful effect, is called resolution.
There are two kinds of independent triads, major and minor. A major triad consists of the fundamental, the major third, and the perfect fifth. Example:—