Table of Contents

Chapter 14

Law 1

The moon has two mean movements. The moon itself rotates on a small circle that does not surround all of the Earth. Moon’s movement on that small circle is called mean lunar anomalyin the original: אמצע המסלול

Mean angular coordinate of the Moon on its epicycle.

. The small circle (epicycle TODO link to Wikipedia) itself rotates on a big circle (deferent TODO link to Wikipedia) that encircles the Earth. The mean movement of the small circle on the big circle that encircles the Earth is called movement of the mean lunar longitudein the original: אמצע הירח.

Law 2

Movement in mean lunar longitude in one day is 13°10′35″6This is part of Law 1..

For longer periods, (remainder) of the movement in mean lunar longitude is:

And in this way you can calculate it for any number of days and years that you want.

Law 3

Movement in mean lunar anomaly in one day is 13°3′54″.

For longer periods, (remainder) of the movement in mean lunar anomaly is:

Law 4

In the beginning of the night to Thursday that is the epoch (TODO measured from what? Chapter 11?) [TODO: link to definition] for these calculations, mean lunar longitude was 1°14′43″ into the constellation of Ram. And mean lunar anomaly on the epoch was 84°28′42″. Now that you know rate of movement in the mean lunar longitude and its value on the epoch to which you add, you’ll calculate mean lunar longitude on any day that you want the same way as you did for the mean solar longitude. TODO: reference

Law 5

After you calculate mean lunar longitude at the beginning of the night that you want, contemplate the sun (TODO: longitude?) and figure out which constellation (zodiac) is it in7This is part of Law 4.. [TODO is this in the text? This is the correction of the mean lunar longitude depending on the mean solar longitude:]

Law 6

Solar Longitude on the Zodiac from to, not including8My understanding of the word usage in the original. Lunar longitude correction
middle of Pisces-middle of Taurus9See Chapter 11, Law 7 on the start of Jewish Zodiac. (TODO reference) 315° 15° 0°
middle of Taurus-beginning of Gemini 15° 30° 0°15′
beginning of Gemini-beginning of Leo 30° 90° 0°15′
beginning of Leo-middle of Virgo 90° 135° 0°15′
middle of Virgo-middle of Libra 135° 165° 0°
middle of Libra-beginning of Sagittarius 165° 210° -0°15′
beginning of Sagittarius-beginning of Aquarius 210° 270° -0°30′
beginning of Aquarius-middle of Pisces 270° 315° -0°15′

The value of mean lunar longitude after you add to it or subtract from it or leave it as it is - that is mean lunar longitude approximately a third of an hour after sunset on the date you are calculating it for. And this is what is called mean lunar longitude at observation time???.

6 This is part of Law 1.7 This is part of Law 4.8 My understanding of the word usage in the original.9 See Chapter 11, Law 7 on the start of Jewish Zodiac. (TODO reference)