The extent to which some branches of trade were carried by the Romans about this time, may be deduced from what is related of Firmus, whose ruin was occasioned by endeavouring to exchange the security of a prosperous merchant for the imminent dangers of a Roman emperor. The commerce of Firmus seems principally to have been directed to the east; and for carrying on this commerce, he settled himself at Alexandria in Egypt. Boasting that he could maintain an army with the produce of paper and glue, both of which articles he manufactured very extensively, he persuaded the people of Egypt that he was able to deliver them from the Roman yoke, and actually had influence sufficient to prevent the usual supplies of corn from being shipped from Alexandria to Rome. His destruction was the consequence. As an instance of his wealth and luxury, Vopiscus relates that he had squares of glass fixed with bitumen in his house. The Roman commerce suffered considerably during the reign of Dioclesian by the revolt of Britain, under Carausius, who, by his skill and superiority, especially in naval affairs, which enabled him to defeat a powerful Roman fleet fitted out against him, obtained and secured his independence. Carausius was murdered by Alectus: against the latter the emperor Constantine sailed with a powerful fleet, and having effected a landing in Britain, Alectus was defeated and slain. This fleet requires to be particularly noticed from two considerations. In the first place, it sailed with a side wind, and when the weather was rather rough,--circumstances so unusual, if not unprecedented, that they were deemed worthy of an express and peculiar panegyric: and, secondly, this fleet was not equipped and ready for sea till after four years' preparation, whereas, in the first Punic war, "within sixty days after the first stroke of the axe had been given in the forest, a fleet of 160 galleys proudly rode at anchor in the sea."