Temperament
The division of the octave.
Equal Temperament. The modern system of tuning divides the octave into twelve equal parts, called semitones. Unequal Temperament (which was formerly used for all keyed instruments, and retained until quite recently for the organ) tuned the natural notes true, and distributed the superfluous interval among the "black" keys. The discovery of the art of equally tempering the scale lies at the foundation of modern music. Without it, the sudden excursions into remote keys would be impossible. Although we have lost something in purity of intonation, the loss is more than made up in the gain of twelve keys, all equally well in tune. Some enthusiasts, generally acousticians, express great dissatisfaction with our modern scale. A sufficient reply is, that the scale that satisfied the ears of, and made possible the music of the great writers from Bach to Beethoven, must of necessity be the best musical scale.
Tempestosamente (It.) (tem-pes-to'-sa-men'teh). Impetuously.