NAVIGATION

Michael Butterfield (1635-1724) was an English instrument maker who worked in Paris during the late 17th century. With the advent of the Grand Tour portable pocket sundials became a fashionable travellers accessory. The scientific instrument trade accordingly manufactured and devised many forms of pocket dial. On this example the brass face is engraved with four hour scales for Latitudes 52º 49º 46º and 43º. A collapsible gnomon adjustable from 40º to 60º lays against the pointer of the bird supporter’s beak. The latitude of many towns in France and Europe, including Paris, London, Madrid, Brussels, Hamburg, Copenhagen and Calais are engraved on the back. The hinged gnomon, a triangular flap made to cast a shadow, could be adjusted accordingly to latitude. The gnomon folds flat and the sundial has cut corners to enable it to be enclosed in a case and carried in a pocket. The adjustable gnomon enabled the time to be read accurately in a variety of locations. Even after watches became popular, pocket dials remained in demand as early watches did not remain accurate for long, and travellers could use the dial to regularly reset their watch.