Lusuerg butterfield dial, 1701.
© Science Museum / Science & Society Picture Library
Butterfield dials are a form of portable sundial, incorporating a compas and a hinged gnomon which could be adjusted to the correct latitude. The instrument was originally designed by Michael Butterfield, an English instrument maker who worked in Paris in the late 17th century. This example is from a set of mathematical instruments made by Dominicus Lusuerg of Rome. Sets of drawing instruments were often made to order for wealthy clients, and were regarded more as an adornment and status symbol than as practical tools.