Jean-Philippe Rameau

 
  The present edition makes available for the first time a complete English translation of Rameau's Traite de l'harmonie, the first and most fundamental of his contributions to harmonic theory. It is a peculiar work, repetitious, often inconsistent, and lacking in clear organization, but a careful reading singles it out immediately as revolutionary in its approach to harmony. Rameau had not yet become aware of the overtone series, he had not yet formulated his theory of the subdominant, . . . .  
 
Jean-Philippe Rameau, Treatise on Harmony, translated with an introduction and notes, by Philip Gossett, Dover Publications, Inc. New York, 1971, page vi
 
 

 
Jean-Philippe Rameau, Treatise on Harmony, translated with an introduction and notes, by Philip Gossett, Dover Publications, Inc. New York, 1971, page xvi
 
 
  schisma schismata [minute interval in music, schism]: the interval between an acoustic pure and an equally tempered fifth--see Diaschisma  
  diaschisma [NL, fr. Gk diaschisma, fr. diaschizein to sever] one of several minute intervals in ancient Greek music 2: a small musical interval (as that between C and D double flat in pure intonation) that together with the schisma comprises the syntonic comma  
 
From Webster's Third International Dictionary