In the reign of Claudius, the knowledge of the Romans respecting the interior of Africa, was slightly extended by the expedition of Suetonius Paulinus; he was the first Roman who crossed Mount Atlas, and during the winter penetrated through the deserts, which are described as formed of black dust, till he reached a river called the Niger.  Paulinus wrote an account of this expedition, which, however, is not extant:  Pliny quotes it.  In the reign of Claudius, also, the island of Ceylon became better known, in consequence of an accident which happened to the freedman of a Roman, who farmed the customs in the Red Sea.  This man, in the execution of his duty, was blown off the coast of Arabia, across the ocean to Taprobane, or Ceylon; here he was hospitably received by the king, and after a residence of six months was sent back, along with ambassadors, to Claudius.  They informed the emperor that their country was very extensive, populous, and opulent, abounding in gold, silver, and pearls.  It seems probable that the circumstance of the freedman having been carried to Ceylon by a steady and regular wind, and this man and the ambassadors having returned by a wind directly opposite, but as steady and regular, had some influence in the discovery of the monsoon.  As this discovery led necessarily to a direct communication between Africa and India, and grea’ly enlarged the knowledge of the Romans respecting the latter country, as well as their commercial connections with it, it will be proper to notice it in a particular manner.

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 Kane 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 Kane 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.”