1911 Encyclopædia Britannica/Monochord
MONOCHORD (Gr. μονόχορδον, κανών μουσικός): med. Lat. monochordum), an instrument having a single string, used by the ancient Greeks for tuning purposes and for measuring the scale arithmetically. The monochord, as it travelled westwards during the middle ages, consisted of a long board, or narrow rectangular box, over which was stretched the single string; along the edge of the sound-board was drawn a line divided according to simple mathematical ratios to show all the intervals of the scale. A movable bridge was so contrived as to slide along over the string and stop it at will at any of the points marked. The vibrating length of string, being thus determined as on the guitar, lute, violin, &c., yielded a note of absolutely correct pitch on being twanged by fingers or plectrum. In order the better to seize the relation of various intervals, a second string tuned to the same note, but out of reach of the bridge, was sometimes added to give the fundamental. (K. S.)