Having straightened out the long-lived confusion about "the short route to India," let us see how Prince Henry went to work. Northern or Mediterranean Africa was well known to Europe, but not the Atlantic coast. There was an ancient belief that ships could not enter tropic seas because the intensely hot sun drew up all the water and left only the slimy ooze of the bottom of the ocean. Cape Nun, of Morocco, was the most southerly point of Africa yet reached; and about it there was a discouraging saying, "Who pass Cape Nun Must turn again or else be gone." Prince Henry, who was called the "Protector of Studies in Portugal," did not believe that rhyme, and determined to show how foolish and untrue it was. His first step was to establish an observatory and a school for navigation at Cape St. Vincent, the most westerly point of Europe and the most southwesterly point of Portugal. To this observatory the prince invited the most learned astronomers, geographers, and instrument-makers then living, that they might all work together with him; and from the little fishing village of Sagres, close to his great observatory, he sent out sailors who, according to an old writer, "were well taught in all rules which sailors ought to know, and provided with the best instruments for navigation." These expeditions began fifty years before Columbus came to Lisbon. Most of them sailed south; out there had always been legends of lands in the west, so westward some of them sailed and found the Azores and the Madeira Islands. These last had been known to English navigators more than a century before, but as England sent no people to occupy and claim them, Portugal took possession of them. How the ownership of all newly-found portions of the globe came to be determined is worth looking into. Ever since the time of the Crusades it was recognized as right that any European Christian ruler might seize the land and property of any Asiatic infidel. If two or three Christian rulers united to seize Mohammedan territory and were victorious, the Pope was to decide which one should own it. But the Crusades were unsuccessful, and so the question of ownership of land outside of Europe never came up until Prince Henry sent out his discoverers. Then, in order to make Portugal's claim very sure to whatever she might find, Pope Martin V. issued an order that all land which might be discovered between Cape Bojador (on the most southerly point of the Morocco coast) and the Indies should belong to Portugal, no matter what navigator discovered it. This was in 1479. Naturally, when his turn came to navigate, Columbus would not be interested in taking the Portuguese path, since, by papal order, he would have to turn over to Portugal whatever he might discover.