The only writer in the time of Adrian, from whom we can derive any additional information respecting the geography and trade of the Romans, is Arrian. He was a native of Nicodemia, and esteemed one of the most learned men of his age; to him we are indebted for the journal of Nearchus's voyage, an abstract of which has been given. His accuracy as a geographer, is sufficiently established in that work, and indeed, in almost all the particulars respecting India, which he has detailed in his history of the expedition of Alexander the Great; and in his Indica, which may be regarded as an appendix to that history. He lived at Rome, under the emperors Adrian, Antoninus, and Marcus Aurelius, and was preferred to the highest posts of honour, and even to the consulship. In the year A.D. 170, he was appointed governor of Pontus, by Adrian, for the special purpose of opposing the Alani, who were invading that part of the empire. His situation and opportunities as governor, enabled him to derive the most accurate and particular information respecting the Euxine Sea, which he addressed in a letter to Adrian; this Periplus, as it is called, "contains whatever the governor of Pontus had seen, from Trebizond to Dioscurias; whatever he had heard from Dioscurias to the Danube and whatever he knew from the Danube to Trebizond." The letter begins with the arrival of Arrian at Trebizond, at which place, the artificial port already noticed was then forming. At Trebizond he embarked, and surveyed the eastern coast of the Euxine Sea, visiting every where the Roman garrisons. His course led him past the mouth of the Phasis, the waters of which, he remarks, floated a long time on those of the sea, by reason of their superior lightness. A strong garrison was stationed at the mouth of this river, to protect this part of the country against the Barbarians; he adds, however, in his letter, that the new suburbs which had been built by the merchants and veterans, required some additional defence, and that he had, accordingly, for the greater security of the place, strengthened it with a new ditch: he ended his voyage at Sebastapolis, the most distant city garrisoned by the Romans. The description of the coasts of Asia, from Byzantium to Trebizond, and another of the interior, from Sebastapolis to the Bosphorus Cimmerius, and thence to Byzantium, is added to his voyage. The great object of this minute and accurate survey was to enable the emperor to take what measures he might deem proper, in case he designed to interfere in the affairs of the Bosphorus, as well as to point out the means of defence against the Alani, and other enemies of the Roman power.