Tablet sundial, German, 1597.
© Science Museum / Science & Society Picture Library
This gilt bras folding pocket sundial is oriented by means of its built in compas. The time is shown by the shadow of a tautened string falling upon a scale of hours which surrounds the compas, and the string also shows the time on a vertical scale on the underside of the lid. It indicates Italian hours, Babylonian hours, planetary or Jewish hours, and the sun's position in the ecliptic.