Among the manuscripts, one of the most well-known of Pliny’s letter 6.16 is Codex Laurentianus Mediceus 47.36, a ninth century manuscript currently residing in Florence, Italy:
The dating of the eruption in the codex reads as nonum Kal · Septembres (24 August), which standard texts of Pliny’s letters include. One critical text, following the usual date, footnotes in its apparatus Septembres as coming from manuscript M (Mediceus), but the reading is omitted in another medieval manuscript, γ (codex Veronensis deperditus).  Although the manuscript citation is brief, this is another indication that the conventional dating of 24 August relies entirely on the reading in the ninth century codex M. This certainly raises uncertainty concerning the date widely accepted, especially when it is dependent upon one late codex within a number of medieval manuscripts which are not homogenous concerning the dating of the eruption of Vesuvius. One, therefore, must look further into other evidences to gain a more accurate picture of the dating.
To be continued in part 3.
 C. Plini Caecili Secundi: Epistularum Libri Decem, R.A.B. Mynors, ed. (Oxford: Clarendon, 1963), 174. Unfortunately, no other critical notes are given in this edition, except that a (editio Aldina anni 1508) follows M.