Proportion

The theory of Proportio, from the 15th century onward, treats of the different time-signatures and tempo-marks applied to several parts progre ing simultaneously; for instance, in a part composition the integer valor might be marked for the discant in sempus perfectum CQ, and for the ba in temp us imperfectum C, the alto might be in temp us imperfectum diminutum, while the tenor had diminutio in tripla Cf 3; further, changes might be made in any or all parts in the course of the piece, and were indicated by fractions (the signs of proportion; compare Augmentation, above). ALTERATION (a/teratio) was the doubling of the time-value of the second of 2