PENTECONTACHORDON, an old musical instrument of the harpsichord kind, invented by Colonna, a Neapolitan, in the beginning of the sixteenth century. In it, each tone was divided into four parts, and each of these had its own peculiar wire and corresponding finger-key. The distinct wires were 500. This instrument was evidently one of the same hopeless kind that we have mentioned in the article ORGAN.