lituus

Lit"u*us, n.; pl. Litui. Etym: [L.] 1. (Rom. Antig.) (a) A curved staff used by the augurs in quartering the heavens. (b) An instrument of martial music; a kind of trumpet of a somewhat curved form and shrill note. 2. (Math.) Defn: A spiral whose polar equation is r2th = a; that is, a curve the square of whose radius vector varies inversely as the angle which the radius vector makes with a given line.

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