Time in ancient Egypt
By Anthony Holmes
Our modern civilisation is obsessed, with time. At one end
of the scale estimates put the age of the universe at 14 billion years and planet
Earth at 4.5 billion years, an unimaginable length of time. At the other end of
the scale the winner of a race may be decided by hundredths of a second. Scientists
in their chronic search for accuracy, divide time to into nanoseconds (one
billionth of a second). Physicists hunting for elusive boson particles divide
time into yoctoseconds; a million, billion, billion of which are required to make
one single second - inconceivable!
When and where did our urge to measure time begin?
It is reasonable to assume that the concept of time has been
with mankind since he became a thinking entity. The arrow of time flies inexorably
forward from birth to death, never reversing direction. The measurement of time
became a challenge to man as soon as he registered the repetitive character of
certain natural events, the most recognisable of which would have been the
rising and setting of the sun. The rhythm of the sun was a factor that resulted
in the ancient Egyptians assigning the sun divine status. The sun was imagined
to be Ra, a divinity in a solar boat; or Ra-Harakhte, a high flying falcon; or
the Aten, a simple red disc. The sun god influence on man and on his crops
caused Ra to attain celestial pre-eminence. The cult of Ra was syncretised (combined)
with other gods such as Atum-Ra and Amun-Ra to increase their power. The king
was perceived to the Son of Ra and kings’ names invariably contained a
reference to Ra’s pleasure or satisfaction with his reign.
The greatest fear the ancient Egyptians had was that the
sun, having died in the west at night, would not rise again in the east the next
morning. Complex myths arose around Ra’s nightly battle to traverse the nether
regions in order to arrive at the eastern horizon where Kheper-Ra would raise
the sun into the sky to commence a new day.
The simple regime of the sun rising and setting was
insufficient to provide hunter-gatherers with a prediction of the seasonal
behaviour of animals and the fruiting of plants. The foragers observed the prime
growing period to be the time the sun was warmer and beamed down longer. The
concept of seasonal change and the annual cycle was born.
As desertification forced the tribes of proto-Egypt to trek towards
the available water in the Nile
River Nile flood. The lunar cycle provided
the first measure they needed, but Thoth, the god of the moon proved to be somewhat
unreliable. After thirteen lunar cycles Thoth misplaced a day, and after 22
years a whole lunar month was lost. A more reliable count was required. The
Egyptians turned to the stars.
The goddess Isis, sister of Osiris and mother of Horus, was
associated with the star Sirius, the brightest star in the night sky. Sirius
appeared above the horizon just before sunrise (called its heliacal rising) at the time of the Nile
flood, signifying the start of the year. As the year progressed, Sirius rose
earlier every night until eventually
it was no longer visible in the sky at dawn because it had already set below
the western horizon. Seventy days later Sirius reappeared just before dawn.
By counting the days between one heliacal rising of Sirius and the next, the
Egyptians determined that the year comprised 365 days. Armed with this
information they constructed a calendar for the year comprising twelve months
of 30 days each with five extra days to celebrate the birthdays of the children
of Earth-god Geb and Sky-god Nut. The months were divided into three periods of
ten days each. Each four month period of the year constituted a season. The
three seasons were Inundation (Akhet), Growing (Peret) and Harvesting (Shemu). The
Egyptians believed they had the year all figured out. As we now know they were
close, but the extra quarter day that we accommodate every leap year, took its
toll. By the time 730 years had elapsed the flood was still arriving with the heliacal
rising of Sirius, but the calendar had slipped a full six months. The physical
seasons were no longer aligned with the calendar.
For the scientists: Sirius does not move retrograde across the
sky like other stars, a phenomenon known as the precession of the equinox.
Sirius remains the same distance from the equinoxes — and so from the solstices
— throughout the centuries, despite precession.
For the same reason, the helical rising of Sirius does not slip through
the calendar at the precession rate of one day per 71.6 years, as other stars
do. This remarkable stability within the solar year may be the reason the
Egyptians used it as a basis for their calendar. No other star would have sufficed.
The Sirius year is 365.25 days versus the more accurate measure of 365.2564
days. The small differential would have only created a nineteen day discrepancy
over the entire three thousand years of ancient Egyptian history.
The establishment of the year was a great step forward in
the measurement of time. However the subdivisions of the day still had to be
sorted out. If a day was the period Ra took to sail his boat across the sky,
simply dividing it into twelve periods called hours would not have worked. Days
differ in length between summer and winter, so hours in summer would have been
longer than winter hours. Such division resulted in
‘temporal’ hours. While hours of the day could be measured by the movement of a
shadow cast by a stick (precursor to the sundial), measuring hours of darkness
was a more difficult task.
Why measure the hours of darkness when one is
asleep? A fair question, but man’s curiosity knows no darkness. The Egyptians noted that the helical rising of certain
stars matched the first day of the 36 successive ten-day periods and called
these stars decans. During any one night, a sequence of twelve decans were seen
to rise and were used to count the hours. Ra’s journey through the
underworld at night was divided into hours and each hour was assigned a
particular challenge. The scenes on the ceiling of Dendara Temple Greenwich
of ancient Egypt ).
The water clock or clepsydra, basically a conical vessel with a drip hole in the
base, may have found early use in some form in China
and India , but its invention
is generally attributed to one Amenemhat who made a water clock for king
Amenhotep I in Egypt
in the 16th century BC. It was used to measure the hours of darkness
and also to measure the duration of speeches in the courtroom (among other
duties). Apparently advocates at law were as loquacious then as they are today!
The water clock provided the Egyptians with a device for the repetitive measurement
of the duration of an hour, both by day and by night. A water clock carved from
alabaster, attributed to the reign of Amunhotep III (c.1380BC), may be viewed
in the Egyptian Museum
The use of temporal hours (hours of differing length
depending on the time of year) was
not sufficiently accurate for astronomers. In Alexandria Europe
was made when weight driven mechanical clocks were developed in the fourteenth
century AD.)
In addition to secular events there were other very
important reasons for knowing the time of day and the day of the year - reasons
of a divine nature. The ancient Egyptians, particularly the priesthood, required
to measure time so that they could fulfil their divine obligations. Gods were
believed to take up residence in the statues carved of their perceived
likeness. In consequence each statue had to be carefully tended by the priests or
the god would leave. Strict regimes of washing, dressing the statue and
providing nourishment in the sanctum were established in the temples and these
had to adhere to a strict time-table. In addition to the daily routine, the festivals,
the ‘holy’ days of veneration allocated to the various gods had to be
celebrated regularly, according to the calendar.
There does not appear to have been a long count of years in
ancient Egypt
beginning at year one and continuing uninterruptedly. Each successive reign
began a new count of years, so that we have records of year one, two etc. of
the king’s reign. However the absence of a continuous record of the dates of
events means that historians do not always agree. Choose three books on ancient
Egypt
and you are likely to find three different dates for the reign of the same
king! Despite this shortcoming (in our view), ancient Egyptians who were driven
by both practical and divine considerations are worthy to be among the civilisations
who qualify as the ‘fathers of time.’
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