The Meantone family of temperaments strives for extremely clean major thirds in 8 keys, 
pushing all imperfection into the four remaining major thirds. Theoretically correct 
meantone temperaments have eleven fifths exactly the same size. Another characteristic 
is the augmented fifth (actually a diminished sixth) at Ab, the "wolf" fifth. In any meantone 
temperament, one-third of the potential harmony was intolerable. 

• Aaron: 1/4 syntonic comma. 

• Zarlino: 2/7 syntonic comma. 

• Huygens: Based on 31 equal divisions of the octave.

• Keller: Almost 1/5 Ditonic. A German harpsichordist who lived in England. He wrote: 
  "Sharp thirds must be as sharp as the ear will permit, and all fifths as flat as the 
  ear will permit." Keller had equal-beating major triads.

• Romieu: 1/7 comma. 

• Marsh: 4/25 syntonic. Although Well temperament was quite prominent, Marsh's 
  philosophy was that is better to have only two-thirds of the keyboard harmony 
  tolerably in tune… he disapproved of tempering for the sake of the characters of the keys.