The exports from this island to the continent were considerable. Camden tells us, that every year not less than eight hundred vessels laden with corn alone were sent out of it. Certain it is, that the imperial government would expect an adequate return for the expenditure occasioned by the troops in this country, and that the commodities of the continent would not be transmitted to the occupants of the Wall from motives of mere benevolence. Lead, which is now so abundant in the three northern counties, would probably form one article of export, and corn another. Those who have noticed the fertility of some portions of the region watered by the Tyne, will be able to conceive how luxuriant were the harvests which its alluvial soil produced when first turned up by the plough. It is certain that coal has been wrought to some extent in Roman times, and some of it may have been exported.
No place in the north of England was so well fitted as Newcastle to be the emporium of the commerce of the North. Situated upon a noble river, at about ten miles from its mouth, it combined the naval advantages of the coast, with the security of an inland situation. The wealth arising from the commerce of the port would increase its importance, and the facility with which foreign news and foreign luxuries could be obtained, would render it the frequent resort of those prefects and tribunes whose usual posts were in bleaker and more inhospitable regions. The fact that the river was at this part spanned by a bridge of many arches, is a striking indication of the importance of the place even in the days of the emperor Hadrian.
No account has come down to us of the state of Newcastle in the days of Roman occupation, but if, after it had been deprived of the advantages which the residence of the mural garrison conferred upon it, the venerable Bede calls it 'an illustrious royal city'—'_vico regis illustri_'—we must conclude that it was a place of considerable importance. The natural advantages of the situation struck the eye of Camden; ‘Now’, says he, ‘where the Wall and Tine almost meet together, Newcastle sheweth itself gloriously the very eye of all the townes in these parts.’
Under these circumstances, there seems to be no reason why the walls of PONS ÆLII should form the usual military parallelogram any more than Roman Rochester, or Pompeii, or Rome itself, much less that the station should occupy an area of little more than three acres.