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AUTOLYCUS ON RISINGS AND SETTINGS 333
‘ apparent ’ morning- and evening-risings and settings of fixed
stars. The ‘true’ morning-rising (setting) is when the star
rises (sets) at the moment of the sun’s rising; the ‘ true ’
morning-rising (setting) is, therefore invisible to us, and so is
the ‘true’ evening-rising (setting) which takes place at the
moment when the sun is setting. The ‘apparent’ morning
rising (setting) takes place when the star is first seen rising
(setting) before the sun rises, and the ‘ apparent ’ evening
rising (setting) when the star is last seen rising (setting) after
the sun has set. The following are the enunciations of a few
of the propositions in the treatise.
I. 1. In the case of each of the fixed stars the apparent
morning-risings and settings are later than the true, and
the apparent evening-risings and settings are earlier than
the true.
I. 2. Each of the fixed stars is seen rising each night from
the (time of its) apparent morning-rising to the time of its
apparent evening-rising but at no other period, and the time
during which the star is seen rising is less than half a year.
I. 5, In the case of those of the fixed stars which are on the
zodiac circle, the interval from the time of their apparent
evening-rising to the time of their apparent evening-setting is
half a year, in the case of those north of the zodiac circle
more than half a year, and in the case of those south of the
zodiac circle ,less than half a year.
II. 1. The twelfth part of the zodiac circle in which the
sun is, is neither seen rising nor setting, but is hidden; and
similarly the twelfth part which is opposite to it is neither
seen setting nor rising but is visible above the earth the whole
of the nights.
II. 4. Of the fixed stars those which are cut off by the
zodiac circle in the northerly or the southerly direction will
reach their evening-setting at an interval of five months from
their morning-rising.
II. 9, Of the stars which are carried on the same (parallel-)
circle those which are cut off' by the zodiac circle in the
northerly direction will be hidden a shorter time than those
on the southern side of the zodiac.