The Cosmographer makes a break after Corbridge, stating that ‘there are civitates in that Britain which exist in a straight line from one side to another, that is from sea to sea, and which divide Britain into a third part.’ This statement alone shows that the Cosmographer used a map which showed Britain both south of the Wall and north of it. It is far from “certain that a different map provided the Cosmographer with his source” for the northern area, as Rivet and Smith (1979, 193) wish us to believe.
They have seen a large number of correspondences between Ptolemy and the Cosmography for Britain north of Hadrian’s Wall, many hidden in the corruptions of the latter text. Because the map also showed a Wall on the line of the Firth-Clyde isthmus, they deduce (1979, 196) that it must have been later in date than Ptolemy and conjecture that it was a Severan compilation based on a Flavian military map which was the ultimate source of Ptolemy’s information. They present a strong case, and have certainly helped elucidate some of the difficult names provided by the Cosmographer for this area. However, I believe that their argument is wrong.
Firstly, some of their supposed correspondences with Ptolemy involve tendentious emendations (particularly in the case of the Antonine Wall). When examined critically, these points of contact simply do not exist; they can be conjectured, but this can be no more than an hypothesis. More damning is the analysis of Jones and Mattingly (1990, 33) who have shown that whereas the Cosmographer maintained some form of logic in his listing of names to the south of Hadrian’s Wall, the identifications proposed by Rivet and Smith suggest that he abandoned all logic to the Wall’s north. This is clearly wrong, as I have already argued for south-western Britain, and an alternative analysis of the text is presented here.
The basis for this alternative treatment remains Ptolemy’s Geography, the starting-point for all explorations of Romano-British placenames in northern Britain. Sir Ian Richmond’s work (1958a, 131) has become a classic in interpreting what is a difficult part of Ptolemy’s text, given the distortion to the shape of Britain north of the Tyne-Solway isthmus, and Rivet and Smith have been criticised for abandoning his framework (Frere 1980, 421; Fulford 1982, 453). However, Rivet’s analysis of the places (as opposed to coastal features) which he sees as being based on a grid derived from itineraries or troop movement records (Rivet & Smith 1979, 123) is a huge step forward in our understanding of the geography of northern Britain in the late first century AD.
In the analysis which follows, I have accepted Rivet’s hypothesis about Ptolemy’s placenames. I have not, however, always followed his identifications of those places. This is partly because, as Rivet himself acknowledges (Rivet & Smith 1979, 123), the Ravenna Cosmography is helpful in adding identifications in this poorly understood area. By identifying breaks in the Cosmography, we can increase knowledge of the road network and points along it which not only fill in the gaps between the nodal points listed by Ptolemy but also extend along other routes. Moreover, some of Rivet and Smith’s identifications of places named by Ptolemy can be questioned both on the grounds of a lack of evidence for Flavian occupation at the sites under consideration and on the basis of the distances between places implied by Ptolemy’s data.