Ptolemaic Shadow Clock

Technical characteristics

Date

305–30 BCE

Type

Sundial

Material

Marble

Dimensions

9.3 x 5.2 x 14.7 cm

Provenance

Theban necropolis

Object name

Sun Dial; sundial; shadow clock

Place recorded

Egypt

Place of origin

Upper Egypt, Thebes, Egypt

Design

Visible features

• Sloping face engraved with a grid of lines • Single line of hieroglyphic inscription along the base • Partial loss of material at the front of the base • Visible weathered stone surface with natural veining

Markings and Inscriptions

The primary surface of the clock is marked with six parallel lines. These lines functioned as seasonal indicators, where each line corresponded to a two-month period of the year. The cycle began at one edge during the winter solstice, moved across the face over the course of six months, and reached the opposing edge by the summer solstice, before reversing the pattern. The reading of the time occurred at the intersection of the seasonal line and the shadow cast on the surface. Oblique lines engraved into the face served to segment the time into individual hours. In addition to these technical markings, a single line of hieroglyphic inscription is preserved along the side of the object's base, providing a decorative and identifying element to the stone.

Discovery and Preservation

The object was discovered in the Theban necropolis by Howard Carter and Lord Carnarvon. It is currently held by the Metropolitan Museum of Art, having entered the collection in 1912 through the Rogers Fund. The item is identified as a representative example of shadow clocks dating to the Ptolemaic period. The preservation of the item is limited, as the front of the base is partially broken. Despite the missing sections, the object remains a clear example of the portable timekeeping instruments that were used in Egypt, particularly during the Greco-Roman era when these types of shadow clocks and sundials became more commonly documented in the archaeological record.

Structural Design and Function

The shadow clock consists of a marble block featuring a distinctively sloping face used to measure the sun's shadow. The current state is fragmentary, with the front of the base broken away. When intact, the instrument would have featured a perpendicular block placed forward of the slope to serve as a gnomon, the component responsible for casting the shadow required to read the device. Operation required the instrument to be positioned on a perfectly level surface while facing the sun. As the sun shifted position, the shadow cast by the gnomon would land upon the engraved grid of parallel and oblique lines. These lines allowed a user to determine the hour of the day and, based on the specific parallel line utilized, account for the seasonal shift in the sun's height across a six-month cycle.

Identification

Accession Number

12.181.307

Source note

Facts transcribed from the linked source listing or collection record. Attribution and specifications are source-reported and have not been independently authenticated.

Catalogue references

No catalogue numbers recorded. Numbers are only published once transcribed from a verified edition of a standard catalogue — they are never inferred.