Besides the principal ports of Ravenna and Misenum, Augustus stationed a very considerable force at Frejus, on the coast of Provence, forty ships in the Euxine, with 3000 soldiers; a fleet to preserve the communication between Gaul and Britain, another near Alexandria, and a great number of smaller vessels on the Rhine and the Danube. As soon as the Romans had constant and regular fleets, instead of the legionary soldiers, who used to fight at sea as well as at land, a separate band of soldiers were raised for the sea service, who were called Classiarii; but this service was reckoned less honourable than that of the legionary soldiers. The period at which we are arrived seems a proper one to take a general view of the commerce of the Roman empire; though, in order to render this view more complete, it will be necessary in many instances to anticipate the transactions posterior to the reign of Augustus. We shall, therefore, in the first place, give a statement of the extent of the Roman empire when it had reached its utmost limits; secondly, an account of its roads and communications by land; and, lastly, an abstract of the principal imports into it, and the laws and finances, so far as they respect its commerce. 1. The empire, at the death of Augustus, was bounded on the west by the Atlantic ocean, on the north by the Rhine and the Danube, on the east by the Euphrates, and on the south by the deserts of Arabia and Africa. The only addition which it received during the first century was the province of Britain: with this addition it remained till the reign of Trajan. That emperor conquered Dacea, and added it to the empire: he also achieved several conquests in the east; but these were resigned by his successor Adrian. At this period, therefore, the Roman empire may be considered as having attained its utmost limits. It is impossible to ascertain the number of people that were contained within these limits. In the time of Claudius the Roman citizens were numbered; they amounted to 6,945,000: if to these be added the usual proportion of women and children, the number will be encreased to about 20,000,000. If, therefore, we calculate, as we may fairly do, that there were twice as many provincials as there were citizens with their wives and children, and that the slaves were at least equal in number to the provincials, the total population of the Roman empire will amount to 120,000,000. Our ideas of the vastness and wealth of the empire will be still farther encreased, if we regard the cities which it contained, though it is impossible to decide in most instances the extent and population of many places which were honoured with the appellation of cities. Ancient Italy is said to have contained 1197, Gaul 1200, of which many, such as Marseilles, Narbonne, Lyons, &c. were large and flourishing; Spain 300, Africa 300, and Asia Proper 500, of which many were very populous.