the identity or similitude of two ratios. Hence quantities that have the same ratio the one proportion to the other are said to be proportional. Thus, if A be to B as C to D, or 8 to 4 as 50 to 15, A, B, C, D, and 8, Proslambanomenos, 4, 30, and 15, are said to be in proportion, or are simply called proportional.

Harmonical or Musical.** See Music, and Temperament.

**PROPOSITION.** See Geometry.