When Rome came into possession of Egypt, its commercial intercourse was conducted chiefly through the port of Berenice, while the port of Myos Hormus was in a great measure abandoned. Yet some trade was still carried on from this port as also from Leuke Kome, on the north-western coast of the Red Sea, near the entrance to the Gulf of Akabah. The whole of these ports being in possession of Rome, there were custom-houses established at each, with Roman officers to collect the duty of twenty-five per cent. imposed on _all_ articles of import and export, as well as Roman garrisons to enforce its payment, where necessary. Caravans from Petra and from the shores of the Mediterranean, brought to Leuke Kome the manufactures and other produce of the North, destined for shipment to the East, while Berenice became the chief port for the manufactures of Rome and of the West, which were conveyed up the Nile, by the route described, to Coptos, and thence forwarded by caravan. Caravans also, from Thebes and other places in Upper Egypt, were the agents of an extensive trade through Berenice and Myos Hormus. Pliny, as has been stated, when compared with Arrian, gives a clear account of the length of time required to make the voyage from Berenice to the straits of Bab-el-Mandeb, a distance between of five and six hundred miles; and the whole of this question has been fully examined by Dr. Vincent. [Sidenote: Outwards.] It would seem that the chief anxiety of the fleets of those days arose from the intricacy and consequent danger of the navigation, even with a favourable wind, within the Straits, and hence that vessels invariably anchored during the night when an opportunity offered. But after passing Bab-el-Mandeb, the steady influence of a favourable monsoon enabled the pilots to make a continuous and comparatively rapid passage. Those ships destined for the more distant voyage to Malabar remained at Okelis (the modern Ghella or Cella), near Aden, for a longer time than those whose destination was only Guzerat. The pilots had observed from the commencement of this new route to India, that the interval between the change of the monsoons was invariable, not merely fluctuating, but that in June and July the weather sometimes proved so tempestuous as to render the navigation of the Indian Ocean perilous, if not almost impracticable; that in August and September the winds become more settled, and that by the month of October fine weather, with steady breezes, could be depended upon. Accordingly, one portion of the fleet, which left Berenice about the 10th of July, arriving at the mouth of the Arabian Gulf within a month, remained at Okelis for a week, ten days, or a fortnight, and by this arrangement the vessels bound for the coast of Malabar reached their destination at the best season of the year.[236] [Sidenote: Homewards.]