In many publications, we read that the eruption of Mt. Vesuvius happened on a hot summer day in August of 79 C.E. (see, e.g., Wiki under Eruption of AD 79). Recent research, however, is beginning to challenge this traditional view with a later date in the autumn of that year. If this is so, this may paint a more accurate picture of the chronology of the disastrous events which took place in the area of the Bay of Naples in the year 79. I will survey (surveys usually cannot do it justice!) some of the evidences which reveal a more determinative view for an autumnal date for the eruption. Some of the items for discussion are Pliny the Younger’s account of the eruption (Letter 6.16), autumnal harvests, clothing, literary, numismatic, and inscriptional evidences.
The Plinian record
In the early years of the second century C.E., writing at the request of his friend Tacitus, Pliny the Younger retells the account of his uncle’s rescue operation and death during the eruption of Mt. Vesuvius in the year 79 C.E.  The conventional dating for the eruption, which primarily comes from Pliny’s account (Ep. 6.16.4), is 24 August.  Pliny writes,
- On 24 August, almost the seventh hour, my mother points out to him (Pliny’s uncle) that a cloud appears of both an unusual size and appearance.
- Nonum kal. Septembres hora fere septima mater mea indicat ei apparere nubem inusitata et magnitudine et specie (Pliny, 6.16.4).
This given date has been published in many modern works without question. On a popular level, a booklet published for the Pompeii exhibit A Day in Pompeii, having recently been concluded in Charlotte, North Carolina with its 4-city tour, opens with, ‘Pompeii is one of the most famous and tragic cities of antiquity. On August 24, A.D. 79, Pompeii and the surround area vanished under a thick layer of volcanic ash when nearby Mount Vesuvius suddenly erupted.’  This dating, however, is entirely dependent on Pliny’s account–an account only extant in medieval manuscripts. Scholars have noted that, among the Plinian manuscripts, there are variations of the actual dating.  Berry writes that in the manuscripts the various dates are IX Kal. Semptembres (24 August), IX Kal. Decembris (23 November), Kal. Novembris (1 November), and III Kal. Novembris (30 October).  As it is very common for scribes to make matters confusing, whether accidental or intentional alterations made through the process of transmission, Roman dating within itself can be confusing. Mary Beard comments that, ‘Pliny certainly describes the eruption, but as with almost all dates in Latin literature they get awfully mangled in the process of centuries of copying by hand. We don’t actually know what Pliny wrote (or, of course, even if he remembered right).’ 
To be continued….
 Pliny’s extant letters of the eruption and his uncle’s death during the rescue are letters 6.16 and 6.20. For a printed Latin-English edition see Pliny, Book VI in Letters, Books I-VII, vol. 1 (Loeb Classical Library. Cambridge: Harvard University Press, 1969).
 A.N. Sherwin-White, The Letters of Pliny: A Historical and Social Commentary (Oxford: Clarendon Press, 1966), 372, writes that this dating is dependent upon Pliny.
 A Day in Pompeii (Seattle: Documentary Media, 2007), 4. Casually browsing another popular-level work, by Benedicte Gilman, Ashen Sky: The Letters of Pliny the Younger on the Eruption of Vesuvius, illustrated by Barry Moser (Los Angeles: Getty Museum, 2007), one can easily find the traditional August dating (7, 8, 9, 11). Many more examples can be given, but these are simply two current examples.
 A few examples, Umberto Pappalardo, ‘L’eruzione pliniana del Vesuvio nel 79 d.C.: Ercolano,’ in Volcanology and Archaeology, Pact 25, C.A. Livadie and F. Widermann, eds. (Strasbourg: Council of Europe, 1990), 210; Joanne Berry, The Complete Pompeii (London: Thames & Hudson, 2007), 20; Mary Beard, The Fires of Vesuvius: Pompeii Lost and Found (Cambridge: Belknap Press, 2008), 17.
 Berry, 20. G. Rolandi, A. Paone, M. Di Lascio, and G. Stefani, ‘The 79 AD Eruption of Somma: The Relationship Between the Date of the Eruption and the Southeast Tephra Dispersion,’ Journal of Volcanology and Geothermal Research 169 (2007): 94, note that the manuscript indicating the date 30 October is ‘now lost.’ See the Wiki article under ‘Date of the eruption’ for a reference to this research. The article abstract and PDF purchase can be found here.
 Beard, on her weblog, A Don’s Life: ‘10 Things You Need to Know About Pompeii.’