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Published online by Cambridge University Press: 22 September 2016
This article is addressed to anyone who has ever doodled idly with a fixed compass on a blank sheet of paper. Perhaps he has drawn a circle centre O, picked a point P1 on it, drawn a circle centre P1 intersecting the original circle at P2 and P3, drawn a circle centre P2 producing two new points of intersection, slowly building up an interlacing hexagonal pattern II of points each a distance at least R from each other. Then he has picked some point P* not of II, and drawn a circle centre P*, and almost immediately the pretty pattern has been replaced by a jumble of intersections apparently covering the whole of the paper.