music-glossary: proportion

 
 1.244 proportion
 ================
 
 ES: proporción, I: proporzione, F: proportion, D: Proportio, NL: ?, DK:
 ?, S: ?, FI: suhde.
 
    [Latin: _proportio_] Described in great detail by Gaffurius, in
 _Practica musicae_ (published in Milan in 1496).  In mensural notation,
 proportion is:
 
   1. A ratio that expresses the relationship between the note values
      that follow with those that precede;
 
   2. A ratio between the note values of a passage and the ‘normal’
      relationship of note values to the metrical pulse.  (A special case
      of the first definition.)
 
    The most common proportions are:
 
    • 2:1 (or simply 2), expressed by a vertical line through the
      mensuration sign (the origin of the alla breve time signature), or
      by turning the sign backwards
    • 3:1 (or simply 3)
    • 3:2 (_sesquialtera_)
 
    To ‘cancel’ any of these, the inverse proportion is applied.  Thus:
 
    • 1:2 cancels 2:1
    • 1:3 cancels 3:1
    • 2:3 cancels 3:2
    • and so on.
 
    Gaffurius enumerates five basic types of major:minor proportions and
 their inverses:
 
   1. Multiplex, if the major number is an exact multiple of the minor
      (2:1, 3:1, 4:2, 6:3); and its inverse, Submultiplex (1:2, 1:3, 2:4,
      3:6)
 
   2. Epimoria or Superparticular [orig.  _Epimoria seu
      Superparticularis_], if the major number is one more than the minor
      (3:2, 4:3, 5:4); and its inverse, Subsuperparticular (2:3, 3:4,
      4:5)
 
   3. Superpartiens, if the major number is one less than twice the minor
      (5:3, 7:4, 9:5, 11:6); and its inverse, subsuperpartiens (3:5, 4:7,
      5:9, 6:11)
 
   4. Multiplexsuperparticular, if the major number is one more than
      twice the minor (5:2, 7:3, 9:4); and its inverse,
      Submultiplexsuperparticular (2:5, 3:7, 4:9)
 
   5. Multiplexsuperpartiens, if the major number is one less than some
      other multiple (usually three or four) of the minor (8:3, 11:4,
      14:5, 11:3); and its inverse, Submultiplexsuperpartiens (3:8, 4:11,
      5:14, 3:11)
 
    He then continues to subdivide each type in various ways.  For the
 multiplex proportions, for example, he indicates how many times greater
 the major number is than the minor:
 
    • If two times greater, the proportion is _dupla_.  If inverted, it’s
      called _subdupla_.  Examples: 2:1, 4:2, and 6:3.
 
    • If three, _tripla_; and its inversion, _subtripla_.  Example: 3:1,
      6:2, and 9:3.
 
    • If four, _quadrupla_; and its inversion, _subquadrupla_.  Example:
      4:1, 8:2, and 12:3
 
    Other proportions were possible, but whether they were frequently
 used is another question:
 
    • 33:9, _triplasuperbipartientetertias_
    • 51:15, _triplasuperbipartientequintas_
 
 
 See also
 ........
 
    Seemensural notation.