STORIES OF CIRCUMNAVIGATING AFRICA 49 it is impossible for men to navigate there on account of the burning heat that prevails." The Venetian map of Marino Sanuto (circ. 1306) embodies the same idea and describes a great tract as uninhabitable by reason of the heat. Even the light of the Moslem geographers grew dim. Ibn Khaldun, himself an African and well acquainted with the facts of African navigation just before Prince Henry 's ex- peditions, describes the Atlantic as " a green or black ocean into which ships do not venture far, for if they get out of sight of land they rarely find their way back." Yet the legend of a passage round Africa to India lived. The Laurentian or Medicean map of 1351, al- though based on conjecture and vague tradition beyond the Gulf of Guinea, shows the trend of that gulf to the eastwards, and a continuous passage round to the Red Sea. But Cape Non, about eight degrees down the African coast from Gibraltar, was reckoned, according to the Portuguese proverb, the safe limit of navigation in mediaeval times, and continued to be so when Prince Henry commenced his explorations. Further south the promontory of Bojador, emphatically " the headland," stretched into the ocean and shut out the Sea of Dark- ness beyond it from the European world. Two Geno- ese galleys sailed in 1291 A. D. toward those latitudes " that they might go by sea to the ports of India," but never returned. Indeed, so barren of results, had been the ancient Carthaginian expedition down the African coast, that only one example of passing Cape
