HARMONIA, in fabulous history, the wife of Cadmus, was, according to some, daughter of Jupiter and Electra, but according to others, of Mars and Venus. Her marriage was a remarkable event in Grecian fable, and rivalled in magnificence those of Perseus, Pirithous, and Peleus. The gods honoured it with their presence, and from them she received a magnificent robe (peplum) and necklace, the workmanship of Vulcan. But these divine gifts afterwards proved the cause of many catastrophes. (See Alcmaeon, Eriphyle.) Harmonia had four daughters, Semele, Ino, Agave, and Autonoe, and a son Polydorus. When every species of calamity overwhelmed the race of Cadmus at Thebes, she attended her husband to Epirus, and was changed into a serpent. (Apollod. iii. 4, 5; Diodor. Sic. iv. 66, v. 49; Eustath.; Dionys. Peri. 391.)
HARMONIC signifies in general any thing belonging to harmony, though in our language the adjective is more properly written harmonical. In this case it may be applied to the harmonical divisions, or to a monochord, or, in a word, to consonances in general. As a substantive neuter, it imports all the concomitant or accessory sounds which, upon the principles resulting from the experiments made on sonorous bodies, attend any given sound whatever, and render it appreciable. Thus all the aliquot parts of a musical string produce harmonical sounds, or harmonics.