Corpus of Electronic Texts Edition
An Irish Astronomical Tract (Author: [unknown])

Caibidil 37

212

DUO IN TERRE LOCA ESSE NOVIMUS, ET CETERA.

We know two places on the earth, one in the straight line under the Arctic Pole, the other in the straight line under the Antarctic Pole where the whole year is one day and one night, since six months are one day, and the other six months one night. Whosoever be at the extreme north of the earth in the place where the Arctic Pole would be, i.e., the axis of the north of the firmament in the straight line above him, would see the circle of the straight line which coincides with the circle of the signs around him, and thus would see the motion of the firmament like the motion of a quern; and thus when the sun enters the straight line in the first part of Aries, it rises in the east under the earth with reference to that place I mentioned, and causes day there, revolving around it: like a quern213, and turns from east to south and from south to west, and from west to north and from north again to the east, and the sun continues thus constantly revolving in the same degree until it arrives at


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Cancer. Then being in the highest degree it can possibly reach, over that place, it divides that long day into two equal parts, and from that gradually sinks until it comes to the end of the day, when it deprives the aforesaid place of its light. And thus there is day in that place, from the middle of the month of March until the middle of the month of September.

When the sun enters the first point of Libra, night begins to darken the same place, and the sun is then moving in a circuit, like a quern,214 sinking gradually underneath the earth, until he enters the first point of Capricorn; beyond that it cannot sink, and then occurs the middle of that great night. At that time the sun begins to rise gradually from that place, until it enters the first point of Aries, and day begins again in the place I mentioned. Consequently, there is one long night in that place from the middle of September until the middle of March.

Similarly, whosoever would be in the south of the earth in the place where the Antarctic Pole would be, i.e., with the axis of the firmament directly overhead, would see the circle of the straight line turning like a quern overhead; and when the sun would enter the straight line in the first point of Libra, it would rise in the east under the earth with reference to a person who would be in the place that I mentioned, and day would begin with reference to him, and the sun would revolve like a quern from east to north, and from north to west, and from west to south, and the south to the east of the firmament.

Thus, it continues ever revolving without sinking, with reference to the place I mentioned, until it enters the first point of Capricorn; and when it has arrived at that highest point it can reach, it divides that long day into two parts and continues gradually sinking until it enters the last point of Pisces. It brings the day to a close then, the day which lasts from the middle of September until the middle of March. Then, when the sun enters the first point of Aries, night begins to begins darken the aforementioned place and then the sun keeps revolving and sinking gradually under the earth, until it enters the first point of Cancer, so that it cannot be lower with reference to that place, and then occurs the middle of that great night. The sun continues rising by degrees until it enters the first point of Libra, and the same long day begins again; and the night I described lasts from the middle of March until the middle of September.


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