At the root of many doubts that obscure our understanding of the manner and timing of Tiberius' accession to the principate there lies a chronological puzzle whose solution is perhaps not altogether beyond conjecture. On what date fell the dies imperii of the new emperor? Three (perhaps four) precise, but incorrect, answers are provided by Josephus, Dio and Tertullian. The difficulty is not removed by the brief or tendentious narratives of Velleius, Tacitus and Suetonius which offer us no such date, or of Dio himself. It is the purpose of this paper to argue that Tiberius accepted the principate at the hands of the Senate on a date between 1st and 3rd September, A.D. 14, and that his reluctance to do so is unlikely to have been a consequence of the receipt of news of the Pannonian revolt.

In November or December 1528 a citizen of Lyon was digging the foundations for a house on the northern outskirts of the town. In so doing he turned up the bronze tablet known to us as the Claudian Tablet. This document, copied from the Acta Senatus and displayed in the federal district at Lugudunum, is a verbatim report of the speech pronounced by Claudius in the Senate in a.d. 48 in favour of the admission to that body of certain Gallic chieftains. Forty-one years after its discovery a historian first placed it alongside the literary version of this same speech which we find in the Annals of Tacitus (xi. 24), and we have not yet exhausted the lessons which this vital juxtaposition can offer us. It is not very often that we are able to look over the shoulder of an ancient writer and see how he wields paste and scissors and box of paints. It is therefore with anticipation and relief that we turn to an undeniably authentic document known, in its original version, to Tacitus, and try to measure the historian's fidelity in using it.