Corpus of Electronic Texts Edition
An Irish Astronomical Tract (Author: [unknown])
Caibidil 12
Solent quidam imperiti
asserere, etcetera.
i.e., Some of the ignorant declare that the flood of the river Nile is
caused by the great rains that fall in distant lands, and as the river
fills, it bursts forth throughout the land of Egypt, and what rain does for
the other races, the water of the river Nile does for the Egyptians. I
declare that they have no argument or reason to prove that statement, except
one single theory
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because, as they see the other rivers of the world becomjng swollen by
rains, they think that the river Nile is thus swollen.
I will now prove that that theory is false, because if the rains were the
cause of the flooding of the river Nile, as they declared, it would become
swollen, with no special period for its filling, every time it should rain
heavily throughout the year as the other rivers become swollen. It is clear
to everyone who sees it that that river does not become swollen except at a
particular time of the year, i.e., in the month of August; but when there is
a plentiful fall of rain in some district near Egypt that river becomes
slightly swollen on account of that rain, because rain that falls in
districts distant from Egypt never increases the river Nile, on account of
the great distance of the source of the river from Egypt, and of the
exceeding dryness of the soil; consequently at whatever period of spring or
summer or any other season rain falls, the sandy, very dry soil and the
parching of the sun absorbs the rain water, and does not allow it advance to
the river; or, when the river is swollen from excessive rain together with
the great sudden floods, the heat of the earth around the river is so great,
that no sooner are the floods at their full, than the earth absorbs them.
The water in that river is seldom accidental, and it is always filled bank
to bank with its own water.
As a proof of that: if you made a trench two or three hundred miles long
through the dry earth, although you might pour a great amount of water into
one end of it, the earth would absorb it all before one drop would reach the
other end of it; thus does the parched, hot soil of the river Nile absorb
the waters that fall around it before they reach Egypt; consequently rain is
not the cause of the flooding of the river Nile.
Another fact to prove the same thing as I heard from my own elders: the
Egyptians thought at one period that the river Nile would not rise until the
fairest
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maiden of greatest beauty in Egypt should be cast into it; and because they
were obliged to get the overflow of the river to moisten the earth, since
that is what they have instead of rain, they used to cast the most beautiful
maiden that could be found in the whole land into the river in the beginning
of the month of August, and the hour after that the river used to be filled,
not on account of the woman being cast into it but because its own time had
come, and it used to fill all Egypt around it, and this kind (?) of evil practice (?) was in vogue in Egypt until the time of
Omar, King of Egypt. As he saw her die (?) by that rude, sinful, evil custom
(?) in the beginning of the month of August, he composed a short letter, and
said in it, ‘In the name of the merciful Lord, Omar, King of
Egypt. Life and health to the river Nile, and if it be thy will, O river
Nile, through the powers of God to pour thy water on the land of Egypt, we
pray thee do so now; and if it be not thy will, we have no reliance (?) in
thee.’ He put the letter then into the river, yet not on account of the
letter nor on account of the woman, but because its own time had come, it
overflowed its banks mightily and filled Egypt. Consequently, if that flood
resulted from those rains, since rain falls frequently during the year, the
river would become swollen frequently. Thus as that theory is false, I shall
disclose the true cause of the flood of the river Nile.
I declare that the source of the river is between the east of the world
and the southern quarter; between the west of the world and the northern
quarter, it enters the sea. The atmosphere of Egypt is warm and dry, so that
it but seldom admits wind or clouds or rain to exist in it. For
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although the surrounding countries experience wind, that air condenses and
contracts, so that it is accompanied by a very great storm that clouds or
rain enter the boundary of that air, and when it enters—which is
seldom—there is terrible thunder and very great wind and lightning,
which kills the flocks of Egypt. It is the nature of air in general to
spread and dilate, when it becomes warm; and when it grows cold to press
together, and it contracts and draws towards it everything like unto it. The
sea air is colder in the night than in the day, consequently, when the sun
reaches its mid-day position, through the heat of the sun the air spreads
and dilates and the wind blows from that time until midnight into the mouths
of the rivers which flow westwards into the sea, and (the wind) opposes the
rivers, and drives them forcibly back, and does not permit them to flow into
the sea until the cold of the night lessens the strength of the heat of the
sun; and, consequently, the conflict with the streams results from the heat
of the atmosphere and the flowing into the sea from the coldness of the
atmosphere. As the sea air is warmer in the day than in the night, and it is
owing to the proximity of the sun to us and its distance from us that that
change comes over the atmosphere; thus, at the time of the year the sun is
nearest to us, i.e., the summer, the sea air is hottest. Consequently on the
first day of the month of May until the sun enters the September equinox the
sea-breeze blows eastwards towards Egypt over the river Nile, and joins with
the air of Egypt to set it in motion and expel it from its own place.
Since
that air is dry, heavy, and difficult to move, it opposes the wind and does
not abandon its own place, and since the wind that is always blowing finds
no other course, it turns the river Nile forcibly back, and does not allow a
drop of it to enter the sea, and the same wind
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sweeps much of the sea sand forcibly into the mouth of the river Nile. Consequently, since the river is prevented from flowing into the sea, it
becomes flooded throughout Egypt, and that flood continues as long as the
wind has its own force, i.e., during the time I have just mentioned, from
the first day of May until the September equinox. Then the wind begins to
lose its strength, and the sun leaves its position directly over the sea,
and sinks by degrees in the southern quarter of the world. When the water of
the river finds no opposition from the wind as it did up to this it breaks
the mountain of sand and proceeds on to the sea and departs from Egypt; and
then the Egyptians plough and sow, since they are certain that the river
will not hinder them until that season again. Consequently it is evident
that they would be often hindered earlier than that season if the flood of
the river Nile resulted from rains.
The rivers of the other lands which flow into the Western sea experience
the same flooding although it does not happen to them so much as it does to
the river Nile, for there is only weak movable air, that does not contend
with the wind, and moves in every direction in which it is carried into the
other lands. On that account no other river in (other) countries is as wide
as the river Nile at its flood; and may He who created the river Nile be
blessed for ever in saecula saeculorum.