Butterfield dial

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A Butterfield dial by Charles Francois Langlois, Paris, c. 1725

A Butterfield dial is a portable horizontal sundial designed to be folded flat and used in latitudes between 35° and 60°. It was named after the English gnomonist Michael Butterfield, who was active in Paris around 1690.

The dials were constructed with a hinged gnomon, whose angle could be adjusted for the latitude; the latitude was indicated by the beak of a bird. The gnomon was held in place by a rivet which was displayed by the birds eye, and thumbscrew.

The dial plate had three chapter rings for 44°, 48° and 52° which would be sufficiently accurate to be used between 35° and 60° (roughly between Gibraltar to the Shetland Isles). There would also be a compass and a plumb bob.[1]

Michael Butterfield

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