Quadrant sundial, English, c 1570.
© Science Museum / Science & Society Picture Library
This pocket sundial, made of silver and signed with the name Humphrey Cole, is set for use in a latitude of 51 degrees, 30 seconds (that of London). This type of dial appears to be unique to Cole (d 1591), who was the first English instrument maker to practise the craft of sundial-making which had recently been introduced into England by Protestant refugees from the Netherlands. When in use, the hinged gnomon is set facing the sun with the dial standing on a horizontal surface. The shadow of the edge of the gnomon acros the scales measures the altitude of the sun.