This important discovery is supposed to have been made in the seventh year of the reign of Claudius, answering to the forty-seventh of the Christian era. The following is the account given of it by the author of the Periplus of the Erythrean Sea, as translated by Dr. Vincent: "The whole navigation, such as it has been described from Adan in Arabia Felix and Kanè to the ports of India, was performed formerly in small vessels, by adhering to the shore and following the indention of the coast; but Hippalus was the pilot who first discovered the direct course across the ocean, by observing the position of the ports and the general appearance of the sea; for, at the season when the annual winds peculiar to our climate settle in the north, and blow for a continuance upon our coast from the Mediterranean, in the Indian ocean the wind is constantly to the south west; and this wind has in those seas obtained the name of Hippalus, from the pilot who first attempted the passage by means of it to the east. "From the period of that discovery to the present time, vessels bound to India take their departure either from Kanè on the Arabian, or from Cape Arometa on the African side. From these points they stretch out to the open sea at once, leaving all the windings of the gulfs and bays at a distance, and make directly for their several destinations on the coast of India. Those that are intended for Limurike waiting some time before they sail, but those that are destined for Barugaza, or Scindi, seldom more than three days." If we may credit Pliny, the Greek merchants of Egypt for some years after the discovery of the monsoon, did not venture further out to sea than was absolutely necessary, by crossing the widest part of the entry of the Persian Gulf, to reach Patala at the mouth of the Indus; but they afterwards found shorter routes, or rather stretched more to the south, so as to reach lower down on the coast of India: they also enlarged their vessels, carried cargoes of greater value, and in order to beat off the pirates, which then as at present infested this part of the Indian coast, they put on board their vessels a band of archers. Myos Hormos, or Berenice, was the port on the Red Sea from which they sailed; in forty days they arrived at Musiris, on the west coast of India. The homeward passage was begun in December or January, when the north east monsoon commenced; this carried them to the entrance of the Red Sea, up which to their port they were generally favored by southerly winds.