Ring clock

A ring sundial is a portable type of sundial used in ancient times by travelers and astronomers for time and geographic orientation.

It was used to measure time based on the position of the Sun. It worked on the principle of casting a shadow or letting light through specially made holes, indicating the time on the appropriate scale. Thanks to its design, it allowed for relatively precise determination of the time, especially on sunny days.

The presented clock is constructed of two flat rings fitted together. On the outer (meridional) ring, a scale for setting the geographic latitude is visible. On the inner (equatorial) ring, a universal hour scale (described in Roman numerals) is visible. At the top, there is a handle for hanging the clock. When not in use, the ring clock can be folded flat, so it does not take up much space. In a clock prepared for operation, the planes of both rings are mutually perpendicular.