Hippalus

It was a great event in the history of oceanography and of the world when in the fourth century before our era, the Greek Pytheas burst into the Atlantic with his ships and sailed as far north as the coasts of Great Britain.

It was a similarly great event when Hippalus, about the first century before our era, discovered the monsoon winds of the Indian Ocean, for after that coast routes were abandoned and voyages of six months duration across the open ocean were made to the coasts of India.

The thirty years between fourteen ninety-two and fifteen twenty-two are ever memorable for the great advance made in our knowledge of the surface of the Earth.

Within this period, Columbus sailed across the Atlantic to America.

As in most branches of organized knowledge, it is to the Greeks that we owe our acquaintance with ancient views of this subject.

In the early stages, they possibly learned something from the Phoenicians, who were the great traders and sailors of antiquity, and who coasted along the Mediterranean, ventured through the Straits of Gibraltar, and traded with the British Isles, which they visited for the tin found in Cornwall.

It is even said that one of their admirals, at the command of Necho, king of Egypt, circumnavigated Africa, for Herodotus reports that, on the homeward voyage, the sun set in the sea on the right hand.

But the Phoenicians kept their geographical knowledge to themselves as a trade secret, and the Greeks learned but little from them.

The writers who thus curtailed Africa of its true proportions assumed another continent south of it, which, however, was in the torrid zone and completely uninhabitable.

Now, the northwest coast of Africa was known in Prince Henry's day as far as Cape Bojador.

It would appear that Norman sailors had already advanced beyond Cape Non, or None, which was so-called because it was supposed that nothing existed beyond it.

Consequently, the problems that Prince Henry had to solve were whether the coast of Africa tended sharply to the east after Cape Bojador, and whether the ideas of the ancients about the uninhabitability of the torrid zone were justified by the fact.