Elementary arithmetic, with brief notices of its history... by Robert Potts.

ON TIlE DIVISIONS AND MEASURES OF TIME.

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divided his single subject into many parts, Herodotus, having embraced
many subjects, has formed them into a single whole.
Thucydides in recording events keeps to the order of the years of
the war, and fixes the date of its beginning (book ii. 2) by naming
several events, one of which is the Archonship of Pythodorus at
Athens. With respect to the events which happened long before the
war (book i. 13, 19), he reckons back from the end of the war.
Timseus, who lived in the time of Ptolemy Philadelphus, 283 to
245 B.C., appears to have been the first who applied Olympiads to fix
the dates of events in history. Even so late as 283 B.c., the Arundelian marbles make no mention of Olympiads. Eratosthenes, 191 B.C.,
and Apollodorus, 115 B.C., arranged events by Olympiads and the
order of succession of the kings of Sparta.
The custom of reckoning from the first Olympiad appears to have
been continued to 312 A.D.1 In memory of the victory gained by
Constantine over Maxentius, on the eighth of the Calends of October,
312 A.D., by which entire freedom was given to Christianity, the
Council of Nice ordained that the accounts of years should no longer
be kept by Olympiads, but that instead thereof, the Indiction should
be used by which to reckon and date their years. And after this date
the public mode of reckoning throughout the Roman Empire, both in
the east and in the west, was by periods of 15 years, called Indictions.2
The chronology of early Roman history has been shown to be
still more uncertain than that of Greece. In fact, the early history
of most nations is obscure and doubtful, and hence the confusion and
the contradictions which are met with in the accounts which have
come down to modern times. The epoch, A.u.C., of the foundation
of the City of Rome comes next in order to that of the Olympiads.
Terentius Varro makes this epoch to coincide with the 23rd year
of the Olympiads, or 753 B.C., which has been generally accepted as the
true date of that event. The older records of Rome were burnt by the
Gauls in their attack on the city about 388 B.C. In early times of the
Republic, the Romans distinguished their years by the names of the
consuls for each year in succession. The period of five years was
named a lustrum, and marked the intervals of taking the census of
the people, first by the kings and afterwards by the consuls, but after
the date 310 A.u.c., it was taken by the censors.
The ancient Roman year consisted of 10 months, and was reckoned.
to begin with that month which is now the third month of the English calendar. Numa Pompilius is reported to have reformed the
calendar by adding two months to the year, and thus making it to
consist of 12 months or 354 days, according to the course of the moon.
These two months were named Januarius and Februarius. He afterwards added a day to the month of January, and so made the year to
1 Any year of a given Olympiad may be converted into the corresponding year
B.C. or A.D. by multiplying the complete Olympiad by 4, and adding 1, 2, or 3 to
the product, according as the given year may be the first, second, or third of the
Olympiad. If this number be greater thane 776, then the excess of this number
above 776 gives the year A.D. If, however, this number be less than 776, the excess
of 776 above this number increased by unity will give the date B. c.
2 The Roman Indiction was instituted by Constantine, surnamed the Great, and
was properly applied to certain tributes which were ordered by imperial edicts to be
paid every fifteen years. These tributes, or Indictions, were sometimes found to be
burdens too oppressive to be endured. The name Indiction was afterwards used
simply to denote a period of fifteen years, and was adopted by the church.