IV. THE VALUE OF CAESAR’S ESTIMATE OF THE DISTANCE BETWEEN THE PORTUS ITIUS AND BRITAIN
Rudolf Schneider[2697] insists that it is idle to lay stress on Caesar’s estimate of the distance from the Portus Itius to Britain, first, because he had no means of making an accurate calculation, and, secondly, because we cannot tell whether he reckoned the distance to the nearest point of Britain or to his own landing-place. As regards correspondence with Caesar’s estimate, Schneider continues, there is nothing to choose between Boulogne, Wissant, and Calais: Dover is 34 Roman miles from Boulogne, 25 from Wissant, 28 from Calais. It might perhaps be argued that, if Caesar took his own landing-place as the terminus, it would be hardly safe to ignore his estimate. For Wissant is 27 Roman miles from Deal, and Boulogne 39; and, assuming that Caesar landed near Hythe, Wissant is 32 Roman miles from that port, and Boulogne 37. It appears, however, to me almost certain that Caesar’s estimate referred to the distance from the Portus Itius to the nearest frequented port of Britain;[2698] and it must not be forgotten that the ancient writers generally overestimated the distance from one port to another.[2699] Moreover, it is not absolutely certain that Caesar estimated the distance of the Portus Itius from Britain at 30 Roman miles. XXX is indeed found in all the extant MSS.;[2700] but as Strabo unquestionably used the Commentaries when he wrote his notice of Caesar’s voyage, and estimated its length as 320 stades, it is not improbable that he found in his copy the number XXXX.[2701] Schneider, however, points out that Strabo’s estimate of the length of the south coast of Britain differs from Caesar’s; and the accuracy of the MSS., as regards the number XXX, may perhaps, as he says, be supported by a comparison of Pliny with Caesar. Pliny[2702] says that the shortest passage between Ireland and Britain is 30 miles, and Caesar[2703] says that the passage from Ireland to Britain is equal in length to the passage from Britain to Gaul. On the whole, we may conclude that Caesar’s estimate of the distance between the Portus Itius and Britain does not help us to decide whether the Portus Itius is to be identified with Wissant or with Boulogne. But, in considering the arguments for the identity of the Portus Itius with the mouth of the Somme, Caesar’s estimate must obviously be taken into account.[2704]