Info Catalog music-glossary: mensural notation music-glossary: Musical terms A-Z music-glossary: meter

music-glossary: mensuration sign

 
 1.192 mensuration sign
 ======================
 
 ES: signo de mensuración, I: indicazione mensurale, F: signe de
 mensuration, D: Mensurzeichen, NL: ?, DK: ?, S: ?, FI: ?.
 
    The ancestor of the time signature, mensuration signs were used to
 indicate the relationship between two sets of note
 durations—specifically, the ratio of breves to semibreves (called
 tempus), and of semibreves to minims (called prolatio).
 
    Each ratio was represented with a single single sign, and was either
 three-to-one (ternary) or two-to-one (binary), as in modern music
 notation.  Unlike modern music notation, the _ternary_ ratio was the
 preferred one—applied to the _tempus_, it was called _perfect_, and was
 represented by a complete circle; applied to the _prolatio_, it was
 called _major_ and was represented by a dot in the middle of the sign.
 The binary ratio applied to the _tempus_ was called _imperfect_, and was
 represented by an incomplete circle; applied to _prolatio_, it was
 called _minor_ and was represented by the lack of an internal dot.
 There are four possible combinations, which can be represented in modern
 time signatures with and without reduction of note values.  (These signs
 are hard-coded in LilyPond with reduction.)
 
 “perfect _tempus_ with major _prolatio_”
      Indicated by a complete circle with an internal dot.  In modern
      time signatures, this equals:
         • 9/4, with reduction or
         • 9/2, without reduction
 
 “perfect _tempus_ and minor _prolatio_”
      Indicated by a complete circle without an internal dot.  In modern
      time signatures, this equals:
         • 3/2, with reduction or
         • 3/1, without reduction
 
 “imperfect _tempus_ and major _prolatio_”
      Indicated by an incomplete circle with an internal dot.  In modern
      time signatures, this equals:
         • 6/4, with reduction or
         • 6/2, without reduction
 
 “imperfect _tempus_ and minor _prolatio_”
      Indicated by an incomplete circle without an internal dot.  In
      modern time signatures, this equals:
         • 4/4, with reduction or
         • 2/1, without reduction
 
    The last mensuration sign _looks_ like common-time because it _is_,
 with note values reduced from the original semibreve to a modern quarter
 note.  Being doubly imperfect, this sign represented the (theoretically)
 least-preferred mensuration, but it was actually used fairly often.
 
    This system extended to the ratio of longer note values to each
 other:
 
    • maxima to longa, called:
 
         • modus maximorum,
         • modus major, or
         • maximodus)
 
    • longa to breve, called:
 
         • modus longarum,
         • modus minor, or
         • modus
 
    In the absence of any other indication, these modes were assumed to
 be binary.  The mensuration signs only indicated tempus and prolatio, so
 composers needed another way to indicate these longer ratios (called
 modes.  Around the middle of the 15th century started to use groups of
 rests at the beginning of the staff, preceding the mensuration sign.
 
    Two mensuration signs have survived to the present day: the C-shaped
 sign, which originally designated tempus imperfectum and prolatio minor
 now stands for common time; and the slashed C, which designated the same
 with diminution now stands for cut time (essentially, it has not lost
 its original meaning).
 
 
 See also
 ........
 
    diminution, proportion, time signature.
 

Info Catalog music-glossary: mensural notation music-glossary: Musical terms A-Z music-glossary: meter