A Dictionary of Music and Musicians/Monochord
MONOCHORD (μόνοσ single, and χορδή a string), an instrument consisting of a long box of thin wood with a bridge fixed at each end, over which is stretched a wire or catgut string. A moveable bridge is placed on the box and serves to stop off different lengths of string, in order to compare the relative pitch of the sounds they produce.
The monochord is said to have been invented by Pythagoras, in the 6th century B.C., but he more probably learnt the use of it in Egypt. The principle of dividing a string to obtain different sounds was applied in the Egyptian lute earlier than 3000 B.C. according to Lepsius. Euclid, writing in the 4th century B.C., and Claudius Ptolemy in the 2nd century A.D., make use of the monochord to define the intervals of the ancient Greek scale; and the later musical system of the Persians and Arabs is described by Abdul Kadir in the 14th century by means of a similar instrument. The Helikon was like the monochord, but had several strings. It was much used in the middle ages for teaching just intonation in singing.
For measuring relative or actual pitch to any high degree of accuracy the monochord is now superseded by Scheibler's tuning-fork Tonometer, and by the Siren as improved by M. Cavaillé-Coll. Those who wish to construct a monochord will find the best directions in Perronet Thompson's 'Just Intonation,' p. 71.
- See Helmholtz, 'Sensations of Tone.' pp. 430–7.