The merkhet was an ancient timekeeping instrument. It involved the use of a bar with a plumb line, attached to a wooden handle. It was used to track the alignment of certain star

Star

A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...

s, if they were visible, in order to approximate the time at night (10 stars for the 10 hours of the night, with a total of 24 hours including 12 hours for the day, 1 hour for sunset, 1 hour for sunrise). In this way, it was more efficient than other contemporary devices, such as sundial

Sundial

A sundial is a device that measures time by the position of the Sun. In common designs such as the horizontal sundial, the sun casts a shadow from its style onto a surface marked with lines indicating the hours of the day. The style is the time-telling edge of the gnomon, often a thin rod or a...

s, which were rendered useless during the dark.

Design

The exact design of the merkhet consists of a horizontal bar, usually carved from wood or bone, with a plumb line hanging from a transverse hole at one raised end of the bar, attached to a controlling wooden handle. As deduced by texts and engravings on the inner walls of the temples of Dendera

Dendera

Dendera is a small town in Egypt situated on the west bank of the Nile, about 5 km south of Qena, on the opposite side of the river.-History:...

 and Edfu

Edfu

Edfu is an Egyptian city, located on the west bank of the Nile River between Esna and Aswan, with a population of approximately sixty thousand people. For the ancient history of the city, see below...

, the merkhet was typically used in conjunction with a corresponding sighting tool, which the Egyptians called a bay, itself made from a specially cut palm-rib with a sliced "V" shape at one end. The two together could also be used, as appropriate, to determine North

North

North is a noun, adjective, or adverb indicating direction or geography.North is one of the four cardinal directions or compass points. It is the opposite of south and is perpendicular to east and west.By convention, the top side of a map is north....

.

For the operation to work, two merkhets were required, one aligned with Polaris, the North Pole star

Pole star

The term "Pole Star" usually refers to Polaris, which is the current northern pole star, also known as the North Star.In general, however, a pole star is a visible star, especially a prominent one, that is approximately aligned with the Earth's axis of rotation; that is, a star whose apparent...

. If erected properly, and if a bay was on hand, one could estimate quite accurately the time by observing the transits of certain stars as they crossed the meridian and came into alignment with the two merkhets.

Preservations

A few merkhets have been excavated and preserved, including one that is on exhibition in the Science Museum

Science museum

A science museum or a science centre is a museum devoted primarily to science. Older science museums tended to concentrate on static displays of objects related to natural history, paleontology, geology, industry and industrial machinery, etc. Modern trends in museology have broadened the range of...

 in London

London

London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

. This particular exhibit dates to 600 BC, and, according to a related inscription, belonged to the son of a priest who hailed from a temple dedicated to the Egyptian god Horus

Horus

Horus is one of the oldest and most significant deities in the Ancient Egyptian religion, who was worshipped from at least the late Predynastic period through to Greco-Roman times. Different forms of Horus are recorded in history and these are treated as distinct gods by Egyptologists...

, located close to Edfu in Upper Egypt

Upper Egypt

Upper Egypt is the strip of land, on both sides of the Nile valley, that extends from the cataract boundaries of modern-day Aswan north to the area between El-Ayait and Zawyet Dahshur . The northern section of Upper Egypt, between El-Ayait and Sohag is sometimes known as Middle Egypt...

.