The ancient Egyptians were one of the first cultures to widely divide days into generally agreed-upon equal parts, using early timekeeping devices such as

sundial A sundial is a horological device that tells the time of day (referred to as civil time in modern usage) when direct sunlight shines by the apparent position of the Sun in the sky. In the narrowest sense of the word, it consists of a flat ...

s, shadow clocks, and merkhets ( plumb-lines used by early astronomers). Obelisks were also used by reading the shadow that they make. The clock was split into daytime and nighttime, and then into smaller hours.

Sundials and shadow clocks

Despite

Herodotus Herodotus ( ; grc, , }; BC) was an ancient Greek historian and geographer from the Greek city of Halicarnassus, part of the Persian Empire (now Bodrum, Turkey) and a later citizen of Thurii in modern Calabria ( Italy). He is known f ...

's attribution of the invention of the sundial to the

Babylonia Babylonia (; Akkadian: , ''māt Akkadī'') was an ancient Akkadian-speaking state and cultural area based in the city of Babylon in central-southern Mesopotamia (present-day Iraq and parts of Syria). It emerged as an Amorite-ruled state c. ...

ns in 430 BCE, the earliest known sundials were simple gnomons of Egyptian origin invented around 3500 BCE . More complex devices were developed over time, the earliest surviving one is a limestone sundial that dates back to 1500 BCE, discovered in the

Valley of the Kings The Valley of the Kings ( ar, وادي الملوك ; Late Coptic: ), also known as the Valley of the Gates of the Kings ( ar, وادي أبوا الملوك ), is a valley in Egypt where, for a period of nearly 500 years from the 16th to 11th ...

in 2013. It was found in a housing area of construction workers and its division of daytime into 12 parts was possibly used to measure work hours. Shadow clocks were modified sundials that allowed for greater precision in determining the time of day, and were first used around 1500 BCE. Their major innovation was a modified, more precise gnomon that allowed for the division of night time into 50 parts, with an additional two "

twilight Twilight is light produced by sunlight scattering in the upper atmosphere, when the Sun is below the horizon, which illuminates the lower atmosphere and the Earth's surface. The word twilight can also refer to the periods of time when this i ...

hours" in the morning and evening. The shadow clock gnomon was made up of a long stem divided into six parts, as well as an elevated crossbar that cast a shadow over the marks. This early clock was positioned eastward in the morning, while at

noon Noon (or midday) is 12 o'clock in the daytime. It is written as 12 noon, 12:00 m. (for meridiem, literally 12:00 noon), 12 p.m. (for post meridiem, literally "after noon"), 12 pm, or 12:00 (using a 24-hour clock) or 1200 ( military time). Sola ...

it was rotated to face west to measure shadows cast by the setting sun. The concept of measured shadows were adapted into larger, more public designs in the form of

obelisk An obelisk (; from grc, ὀβελίσκος ; diminutive of ''obelos'', " spit, nail, pointed pillar") is a tall, four-sided, narrow tapering monument which ends in a pyramid-like shape or pyramidion at the top. Originally constructed by An ...

s. Markers around the obelisk would indicate units of time, including morning and afternoon as well as the summer and

winter solstice The winter solstice, also called the hibernal solstice, occurs when either of Earth's poles reaches its maximum tilt away from the Sun. This happens twice yearly, once in each hemisphere (Northern and Southern). For that hemisphere, the winter ...

s for ceremonial purposes.

Merkhets

Using plumb-lines called '' merkhets'', the Egyptians could calculate time at night, provided the stars were visible. Used since at least 600 BCE, two of these instruments were aligned with Polaris, the North

pole star A pole star or polar star is a star, preferably bright, nearly aligned with the axis of a rotating astronomical body. Currently, Earth's pole stars are Polaris (Alpha Ursae Minoris), a bright magnitude-2 star aligned approximately with its ...

, creating a north–south

meridian Meridian or a meridian line (from Latin ''meridies'' via Old French ''meridiane'', meaning “midday”) may refer to Science * Meridian (astronomy), imaginary circle in a plane perpendicular to the planes of the celestial equator and horizon * ...

. By observing certain

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

s as they crossed the line created with the ''merkhets'', they could accurately gauge time.

References

{{Egypt topics

Egypt Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Mediter ...

Timekeeping devices in Egypt Timekeeping devices Timekeeping devices Timekeeping devices Timekeeping devices Timekeeping devices

Sundials and shadow clocks

Merkhets

See also

References