The Lituus reference article from the English Wikipedia on 24-Jul-2004
(provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

Lituus

For thoughtful child sponsors
A lituus (Latin for "crozier") is a spiral in which (in polar coordinates) the angle is inversely proportional to the square of the radius.

image:lituus.png

The lituus is asymptotic to the line θ=0.