Archicembalo

The archicembalo /ɑːrkiˈtʃɛmbəloʊ/ (or arcicembalo, /ɑːrtʃiˈtʃɛmbəloʊ/) was a musical instrument described by Nicola Vicentino in 1555. This was a harpsichord built with many extra keys and strings, enabling experimentation in microtonality and just intonation.

The archicembalo had two manuals, but unlike those on a normal harpsichord these two keyboards were used to provide extra pitches rather than a timbral difference. Both manuals contained all of the usual white and black keys, but in addition each black key was divided into two parts so that a distinction could be made between a sharp or flat note. The lower manual also included black keys between B and C, and between E and F. In total there were 36 keys available in any octave, each of which could be tuned to a different pitch. (manual diagram)

There were two systems of tuning the archicembalo considered by Vicentino:

The observation that extended quarter-comma meantone temperament almost exactly approximates 31 equal was recognized by Huygens in 1661, published in 1691, He says that after making this discovery, he found an earlier mention of the idea in Salinas' report on a 31 tone Italian keyboard, presumably Vicentino's Archicembalo.

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