Hamilton's paper
On Röber's Construction of the Heptagonappeared in the Philosophical Magazine, vol 27 (4th series) (1864), pp. 124-132.
This paper is available in the following formats:
Hamilton discusses an approximate but extremely accurate geometrical construction of a regular hexagon, due to Friedrich Gottlob Röber, who had suggested that this construction was known to the ancient Egyptians, and employed by them in the building of the temple at Edfu.
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D.R. Wilkins