The ordinary traffic of those times was conveyed either on the backs of mules or horses, across Gaul, as was the case with tin, or by the rivers of that country: indeed, for a long period the merchant vessels of Britain were not of a construction to brave the heavy gales and stormy seas of the rude Atlantic, while Gaul was a country peculiarly favoured in the conveniences it afforded for such an inland water transit. Everywhere intersected by navigable rivers running in very opposite directions, goods could be carried between the Mediterranean and the English Channel, or the shores of the Atlantic, with little assistance of land carriage. From Narbo, an ancient commercial port of first-class importance already noticed, goods were carried a few miles overland and re-shipped on the Garonne, which carried them to Burdigala (Bordeaux). In the same way the Loire, the Seine, and the Rhine afforded navigable facilities into the very heart of the country, while all of them were easily connected with the Rhône or its great navigable branches, thus completing the inland water-carriage between the Mediterranean and the western and northern shores of Gaul. [Sidenote: Transit duties.] British goods destined for Rome, or for any port of the Mediterranean, were chiefly conveyed by either of these inland routes, or across country by the few highways or beaten tracks then in use.[448] In the centre of this inland conveyance, at the junction of the Rhône with the Saône (Arar), and within an easy distance of the other navigable rivers flowing in the opposite direction, stood the great inland emporium of Lyons (Lugdunum), a city then of much commercial importance and second only to Narbo. This inland navigation, while of material advantage to the inhabitants of the districts traversed, was, even before the Roman conquest, a source of considerable emolument to the proprietors of the lands adjacent to the rivers, as they were thus able to levy a toll or transit duty on the boats passing through their territories. These duties, we may presume from Strabo, were transferred to the Roman coffers soon after Gaul became a Roman province, as he distinctly asserts that (in his day at least) the duties on the imports and exports of Britain constituted the only species of revenue derived from Gaul by the Romans.[449] It is, moreover, not likely that the government of Rome would permit its subjects to levy dues for their own individual benefit. [Sidenote: Articles of commerce, and knowledge of manufactures and of the arts.]