is onlyfirmly attested, as we have seen, for about two centuries (fourth–third
centuriesBCE), and even then, not without irregularities, there is actually no
compelling reason to believe that it was maintained unchanged under the
Parthians in subsequent centuries.
Cuneiform evidence ends, with Table 2.6(a), in 88/7BCE, but later in the
century Parthian coins become available and may shed light on Babylonian
intercalations. Inscribed in Greek, they give the year according to the Seleucid
Era and sometimes a Macedonian month-name, which may sometimes be
intercalary, although in most cases the name of the intercalary month is not
specified. On this basis, Assar (2003) has attempted to reconstruct middle
Parthian-period intercalations, as tabulated in Table 2.6(b). The record, again,
is terribly sporadic (for example, without any attestation of year 3 of the Saros
Canon cycle). Assar’s reconstruction, moreover, depends on a number of
problematic assumptions, as follows:
- the Macedonian calendar which Parthian rulers used was assimilated
and completely equivalent to the Babylonian calendar. - the Babylonian calendar thus used was based, in this period, on the Saros
Canon cycle (see notes to Table 2.6). - the Seleucid Era used on these coins differed from Babylonian usage: it
began six months earlier, in VII 312BCE, and hence all its years began in
month VII.
The last assumption (3) may be regarded as reasonable, but the same cannot
be said of thefirst (1); the relevance of Parthian dates to the Babylonian
calendar remains, therefore, unclear (see discussion in Chapter 5). More
importantly, it is evident from assumption (2) that this table cannot serve as
evidence that the Saros Canon cycle was followed, without falling into a
circular argument. Every entry in it can only be treated as tentative—especially
when, as in most cases, the month-name is not specified in the sources.
Discussion and conclusionThe evidence surveyed above should lead us to reconsider the origins of the
Babylonian 19-year cycle. It is commonly assumed that the 19-year cycle was a
scientific discovery, the product of advances in Babylonian mathematical
astronomy. Britton (1993, 2007) notes that the introduction of a 19-year
cycle in the latefifth centuryBCEcoincides approximately with a significant
change in the Saros scheme of Babylonian astronomical sources, and suggests
that it was the study of eclipses and their cycles that led to the discovery and
adoption of the 19-year cycle. The argument is that although the Saros cycle of
eclipses is only 18 years long, it would have been noticed that at two lunar
eclipses occurring 19 years apart, the moon is positioned near the same star or
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