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\begin{figure}\begin{center}\BoxedEPSF{lituus.epsf scaled 900}\end{center}\end{figure}

An Archimedean Spiral with $m=-2$, having polar equation


Lituus means a ``crook,'' in the sense of a bishop's crosier. The lituus curve originated with Cotes in 1722. Maclaurin used the term lituus in his book Harmonia Mensurarum in 1722 (MacTutor Archive). The lituus is the locus of the point $P$ moving such that the Area of a circular Sector remains constant.


Gray, A. Modern Differential Geometry of Curves and Surfaces. Boca Raton, FL: CRC Press, pp. 69-70, 1993.

Lawrence, J. D. A Catalog of Special Plane Curves. New York: Dover, pp. 186 and 188, 1972.

Lockwood, E. H. A Book of Curves. Cambridge, England: Cambridge University Press, p. 175, 1967.

MacTutor History of Mathematics Archive. ``Lituus.''

© 1996-9 Eric W. Weisstein