Rule of thirds as a rule for the proportion of warm to cold colors in a painting, and attributes to Smith the expansion of that rule to all proportions in painting: Sir Joshua has given it as a rule, that the proportion of warm to cold colour in a picture should be as two to one, although he has frequently deviated therefrom; and Smith, in his "Remarks on Rural Scenery," would extend a like rule to all the proportions of painting, begging for it the term of the "rule of thirds," according to which, a landscape, having one third of land, should have
Major thirds tuning of major-third and minor-sixth intervals are termed "inverse intervals" in the theory of music. Consequently, chord charts for minor-sixths tunings may be used for left-handed major-thirds tunings; conversely, chord charts for major-thirds tunings may be used for left-handed minor-sixths tunings. Major-thirds tuning facilitates playing chords with closed voicings. In contrast, standard tuning would require more hand-stretching to play closed-voice seventh chords, and so standard tuning uses open voicings for many four-note chords, for example of dominant seventh chords. By definition, a "dominant seventh" is a four-note chord combining a major chord and a minor seventh. For example, the C7 seventh