Lituus
An Archimedean Spiral with 
, 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 locusof the point 
moving such that the Area of a circular Sector remains constant.
References
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.''http://www-groups.dcs.st-and.ac.uk/~history/Curves/Lituus.html.
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