The discovery about 432 B.C. by Meton, an Athenian astronomer, of the Moon's period of 19 years, at the end of which the New Moon occurs on the same day of the year. Upon this he based certain corrections of the lunar calendar. He figured the 19-year cyclic of 235 lunations to consist of 6,939d, 16.5h. This he divided into 125 full months of 30 days each, and 110 deficient months of 29 days each. (v. Lunar Month.) the 235 full months, of 30 days each, totalled 7,050 days; hence it became necessary to suppress 110 days or 1 in 64. Therefore the month which contained the 64th day became a deficient month. As the true Lunation period is 6,939d, 14.5h, his calculations showed a deviation of only two hours. The average date on which a Lunation will occur can be determined from the following table correlating Sun positions with the calendar:
METONIC CYCLE
Golden Number |
Cp 11-30° |
Aq |
Pi |
Ar |
Ta |
Ge |
Cn |
Le |
Vi |
Li |
Sc |
Sg |
Cp 1°-11° |
1 |
11 |
11 |
11 |
10 |
9 |
7 |
5 |
3 |
1-29 |
29 |
29 |
29 |
29 |
2 |
29 |
30 |
29 |
28 |
17 |
25 |
23 |
22 |
19 |
18 |
1 |
18 |
18 |
3 |
18 |
18 |
18 |
18 |
16 |
15 |
14 |
12 |
10 |
8 |
7 |
7 |
7 |
4 |
7 |
7 |
7 |
7 |
6 |
5 |
3 |
1-29 |
28 |
26 |
26 |
25 |
26 |
5 |
26 |
25 |
26 |
24 |
24 |
22 |
20 |
19 |
17 |
16 |
15 |
15 |
15 |
6 |
15 |
15 |
15 |
14 |
13 |
12 |
9 |
8 |
6 |
5 |
5 |
5 |
4 |
7 |
4 |
4 |
4 |
3 |
3 |
1-29 |
27 |
26 |
24 |
24 |
23 |
23 |
24 |
8 |
24 |
23 |
23 |
22 |
20 |
19 |
17 |
15 |
14 |
12 |
12 |
12 |
12 |
9 |
12 |
12 |
12 |
12 |
10 |
9 |
7 |
4 |
3 |
1 |
1 |
0 |
1 |
10 |
1 |
1 |
1 |
1 |
0-28 |
26 |
25 |
22 |
21 |
20 |
20 |
19 |
20 |
11 |
20 |
20 |
20 |
19 |
18 |
17 |
15 |
13 |
10 |
9 |
9 |
8 |
9 |
12 |
8 |
9 |
9 |
8 |
8 |
6 |
4 |
3 |
0-29 |
27 |
27 |
27 |
28 |
13 |
28 |
27 |
27 |
26 |
25 |
23 |
22 |
20 |
19 |
17 |
17 |
16 |
16 |
14 |
16 |
17 |
16 |
16 |
15 |
14 |
11 |
10 |
8 |
7 |
6 |
6 |
6 |
15 |
6 |
5 |
5 |
5 |
4 |
3 |
1-29 |
27 |
25 |
25 |
24 |
24 |
24 |
16 |
24 |
24 |
24 |
23 |
21 |
20 |
19 |
17 |
16 |
15 |
14 |
13 |
14 |
17 |
14 |
13 |
13 |
12 |
11 |
10 |
8 |
6 |
5 |
3 |
3 |
3 |
3 |
18 |
3 |
3 |
2 |
2 |
1-28 |
7 |
25 |
24 |
22 |
22 |
22 |
22 |
21 |
19 |
21 |
22 |
21 |
21 |
19 |
18 |
15 |
13 |
12 |
11 |
10 |
11 |
11 |
To ascertain the Golden number (q.v.) of any year, add 1 and divide by 19: the remainder is the Golden number. If there is no remainder, the number is 19.
