Unicorn, in Astronomy, a southern constellation formed by Hevelius, containing in his catalogue 19 stars, and in the Britannic Catalogue 31.

See MONODON, Cetology Index.

MONOCHORD; an instrument by which the several proportions of musical sounds and intervals, as well in the natural as in tempered scales are tried. Originally it had, as its name implies, only one string; but it is better constructed with two; for, by means of this additional string, we have an opportunity of judging of the harmony of two tempered notes in every possible variety of temperament.

The reader who may wish for further information respecting the construction and use of monochords, may consult the appendix to Mr Atwood's Treatise on Reciprocating Motion, and Mr Jones's observations on the scale of music, monochord, &c. in his Physiological Disquisitions.

Monochord is also used for any musical instrument that consists of only one string or chord; in this sense the trumpet marine may properly be called a monochord.