"Well Temperament" refers to a class of historical musical tuning systems that seek a compromise between the pure intervals of Just Intonation and the flexibility of Equal Temperament. In Well Temperament, the sizes of certain intervals are adjusted to enhance the consonance of common keys while allowing modulation to other keys without excessive dissonance.
Unlike Equal Temperament, which evenly divides the octave into 12 equal semitones, Well Temperament systems adjust specific intervals to achieve better consonance in certain keys. These adjustments create a variety of different Well Temperament tunings, each with its own unique set of interval modifications.
The goal of Well Temperament is to strike a balance between the purity of intervals in Just Intonation and the ability to play in a variety of keys without extreme dissonance. While the intervals in Well Temperament are not as pure as those in Just Intonation, they are more usable across different keys than the intervals in Equal Temperament.
Various composers and theorists from different historical periods have proposed their own versions of Well Temperament, resulting in a range of tunings with varying interval adjustments. Some famous examples include Kirnberger Temperament and Werckmeister Temperament.
Although Well Temperament has historical significance, it has largely been replaced by Equal Temperament in modern music due to the latter's flexibility in modulating between keys. However, Well Temperament remains an important part of understanding the evolution of tuning systems and their impact on the performance and interpretation of historical music.