On a rock in a northern English park stands a bowl of slate mounted on a bronze collar. The Holker dial, of Burlington slate, is derived from the earliest known Sundial, the hemispherium of Berossos, a Chaldean astronomer who worked in the Greek world and developed his invention about 2300 years ago.

The concept has also been used with smaller dimensions, and mounted on a column.

A further derivation has led to the seat dial, the Hemicyclum, a project perhaps suitable for a site overlooking the Aegean.