The left hand column in the table on the 72d page represents the number of days in each month from the days of Julius Cæsar to Augustus, a period of 37 years. The right hand column represents the number of days in the months as they now are, and have been since the change was made by Augustus, 8 B. C. Consequently the rule for finding the day of the week on which events have fallen for the 37 years prior to the last mentioned date, is not perfectly exact, and needs a little explanation here.
The rule itself is given, and fully explained in Part Second, Chapter V, (q. v.) but cannot be applied to the 37 years without some correction. In all the months marked with a star, events fall one day later in the week than that which is indicated by the rule. This should be borne in mind, and make the event one day later in the week than that which is found by the rule. For example, Julius Cæsar was assassinated on the 15th of March, 44 B. C. By giving to February 28 days the first day of March would fall on Wednesday, and, of course, the 15th would be Wednesday. But Cæsar gave to February 29 days, so that the first day of March fell on Thursday, and the 15th was Thursday.
Hence, every event from March to September will fall one day later in the week than the rule indicates. But the rule is applicable to September, for it will make no difference whether there are 29 days in February or 31 in August, there are the same number of days from February to September. But the 31 days in September will cause all events to fall one day later in the week during the month of October, but they coincide again during the month of November. The order is interrupted again in December by giving 31 days to November. See following table:
_As Arranged by Julius_ | _As Corrected by Augustus,_ _Cæsar._ | _8 B. C._ | January, 31 | January, 31 February, 29 | February, 28 March, 31* | March, 31 April, 30* | April, 30 May, 31* | May, 31 June, 30* | June, 30 July, 31* | July, 31 August, 30* | August, 31 September, 31 | September, 30 October, 30* | October, 31 November, 31 | November, 30 December, 30* | December, 31
---------+-----+---------+-----+---------+-----+---------+----- Dominical|Year.|Dominical|Year.|Dominical|Year.|Dominical|Year. Letter. | | Letter. | | Letter. | | Letter. | ---------+-----+---------+-----+---------+-----+---------+----- |B. C.| |B. C.| |A. D.| |A. D. cb | 45 | b | 22 | b | 1 | c | 23 a | 44 | ag | 21 | a | 2 | ba | 24 g | 43 | f | 20 | g | 3 | g | 25 f | 42 | e | 19 | fe | 4 | f | 26 ed | 41 | d | 18 | d | 5 | e | 27 c | 40 | cb | 17 | c | 6 | dc | 28 b | 39 | a | 16 | b | 7 | b | 29 a | 38 | g | 15 | ag | 8 | a | 30 gf | 37 | f | 14 | f | 9 | g | 31 e | 36 | ed | 13 | e | 10 | fe | 32 d | 35 | c | 12 | d | 11 | d | 33 c | 34 | b | 11 | cb | 12 | c | 34 ba | 33 | a | 10 | a | 13 | b | 35 g | 32 | gf | 9 | g | 14 | ag | 36 f | 31 | e | 8 | f | 15 | f | 37 e | 30 | d | 7 | ed | 16 | e | 38 dc | 29 | c | 6 | c | 17 | d | 39 b | 28 | ba | 5 | b | 18 | cb | 40 a | 27 | g | 4 | a | 19 | a | 41 g | 26 | f | 3 | gf | 20 | g | 42 fe | 25 | e | 2 | e | 21 | f | 43 d | 24 | dc | 1 | d | 22 | ed | 44 c | 23 | | | | | c | 45 ---------+-----+---------+-----+---------+-----+---------+-----