Antonine Itinerary, Iter XIV: 1) Isca Silurum to Venta Silurum

For the calculations in kilometres and modern miles in what follows, the equivalents used are the commonly accepted 1,000 Roman paces = 1.48 km or 0.92 modern miles. The edition of Itinerarium Antonini Augusti consulted is that of G.Parthey and M.Pinder, Berlin, 1848. Iter XIV is on p. 233.

How accurate the Itinerary’s distances ever were, and whether/where the manuscript tradition might – perhaps – be corrupt, are problems to acknowledge rather than linger over at this stage. Iter XIV, on which Traiectus lies, starts at Caerleon (Isca Silurum) and ends at Silchester (Calleva Atrebatum), and is an alternative route (alio itinere) to the one via Gloucester. The total distance is recorded as CIII (103,000 paces or 103 Roman miles); and the separate distances given between each stopping point, satisfyingly, add up to exactly CIII. So far, so good.

The first stage of the iter, Isca Silurum (Caerleon) to Venta Silurum (Caerwent),  is given as VIIII mpm or 9,000 paces – c. 13.32 km or 8.28 miles. As the crow flies, the distance between the two is 13.23 km or 8.22 miles. Is that what the Itinerary’s measurements mean, or is it just a coincidence? A coincidence, surely, since mille passus must refer to a distance walked (rather than flown), mustn’t it? [But see future blog on this.] The ‘predicted’ Roman road route between Isca and Venta is roughly along the A48, though little archaeological evidence seems to exist.¹ Following that route (and cutting out some of the wiggles), the distance would be at least 14.42 km or 8.96 miles.

Measured distances: Top, along the A48, bottom, as the crow flies. Click on image for clearer view

There are reasons to think that the measurement of this stage, at least, of the journey ought to be fairly accurate. Firstly, the terrain is easy: along a flattish coastal plain, gently undulating but with no deep valleys, wide rivers, mountains or steep hills to negotiate. It’s therefore not too surprising that the as-the-crow-flies distance is almost exactly as recorded by the Itinerary. Secondly, at 9,000 paces it is one of the shorter stretches between stopping points on this iter (the shortest is 6,000 paces, the longest 20,000). Longer stretches can present more possible deviations and uncertainties; and there are always the unknowable variables introduced by the marching army or whoever measured the distances used by the Itinerary.

The A48 road just past the turning left to Parc Seymour, travelling east.

We can infer that the Itinerary was very accurate in its measurement here if:

a) it was measuring the ‘as the crow flies’ distance or

b) 1,000 paces represented c. 1.6 km/0.99 miles, instead of the commonly accepted 1.48m/0.92 miles. These revised equivalents can be used for calculating the other stages.

Not very much more can be learned from this stretch: there are certainties and uncertainties. Old Somerset, not for the first time, has wandered off the beaten track; but Traiectus may bring us back a little closer to home.

¹ “West of Crick, the road is assumed to follow the route of the modern A48 through Caerwent, though the section between Crick and Cat’s Ash is almost all purely conjectural, except where it passes through Caerwent where it is confirmed by the position of the gates. Although [the] modern A48 consists of a series of straight alignments, these may owe their origin at least in part to turnpiking. To the west of Penhow Castle, Ordnance Survey fieldworkers excavated a short section of agger but little further information was recorded about the results of the excavation”, Roman roads in Southeast Wales. Desk-based assessment, p. 17, report for Cadw by A. Sherman and E. Evans, Sept 2004.



That old chestnut (Chapter One)

Much examined, not yet solved is the puzzle of the placename ‘Traiectus’, referred to in the Antonine Itinerary of the 2-3rd century. In the section on Britannia, Itinerary XIV starts at Isca (Silurum), or Caerleon, and ends at Calleva (Atrebatum) – Silchester.

Most of the stations along the way have been identified, with more or less certainty; but very roughly fourteen miles on from Sea Mills (Abone) and six miles short of Bath (Aquis Solis) is the mysterious ‘Traiectus’. The figures xiiii and vi mean 14,000 passus and 6,000 passus. Given the modern computation of a passus, that would be roughly 13 miles from Sea Mills and 5 1/2 from Bath. The common view is that it coincides most closely with Bitton, on a stretch of the old Roman road between Bath and Hanham on the outskirts of Bristol. The distances match closely enough, but it remains the least certain of the identifications of this Iter.

The River Boyd, taken from the A361 as it passes through Bitton

So, why would it not be? Well, firstly, a traiectus is a crossing, so the argument is that this could be the River Boyd. If so, it must have been a bigger river than it is now – by some considerable margin.

At present it looks like the kind of small waterway which might or might not have needed a stone ford. Wheeled carts or wagons could splash in and out the other side, hardly noticing it. To designate the place ‘Traiectus’ would be to dignify it beyond its obvious desserts.

The River Frome at Frenchay

After leaving Sea Mills and before arriving at Bitton, the traveller would also have to cross the River Frome, not the widest river in all Britain, but this is still (at the present time, it must always be remembered) only the size of river that could be easily forded, without even the need of a bridge.

Traiecti must have been ten a penny if river crossings the size of that over the Boyd merited the name.

The other point is that Bitton has no very strong Roman connections. A nearby camp, once considered to have been Roman, seems more likely to have been medieval and there are no more than a few odds and ends in the way of Roman remains. So for the Romans, the most notable aspect of Bitton would have been – its river crossing …

On the other hand, more puzzling than that, the Itinerary as it survives makes no mention of the fact that to get from Caerwent to Sea Mills a rather wider stretch of water must be crossed than the River Boyd. An alternative suggestion for Traiectus is that it referred to the crossing of the Severn Estuary itself. Can that be supported?