Septimal kleisma

From Wikipedia, the free encyclopedia

In music, the ratio 225/224 is called the septimal kleisma.^[1] Another name for it is the marvel comma^{[citation needed]}, since the temperament tempering it out is sometimes called the marvel temperament^{[citation needed]}, . It is an interval of approximately 7.7 cents. Factoring it into primes gives 2^-5 3² 5² 7^-1, which can be rewritten 2 ^-1 (5/4)² (9/7). That tells us that it is the amount that two major thirds of 5/4 and a septimal major third, or supermajor third, of 9/7 exceeds the octave^{[citation needed]}, . If the septimal kleisma is tempered out, as it is for instance in miracle temperament, septimal meantone temperament and in most equal temperaments, for example 12, 19, 22, 31, 41, 53, 72 or 84 equal, then an augmented triad consisting of two major thirds and a supermajor third making up an octave becomes possible^{[citation needed]}, . The existence of such a chord, which might be termed the septimal kleisma augmented triad, is a significant feature of a tuning system^{[citation needed]}, .

The septimal kleisma can also be viewed as the difference between the diatonic semitone (16:15) and the septimal diatonic semitone (15:14)^{[citation needed]}, .