The accustomed routes of Oriental trade were cut off in the fifteenth century by the Ottoman Turks 293 Necessity for finding an "outside route to the Indies" 294 CHAPTER IV. THE SEARCH FOR THE INDIES. _EASTWARD OR PORTUGUESE ROUTE._ Question as to whether Asia could be reached by sailing around Africa 295 Views of Eratosthenes 296 Opposing theory of Ptolemy 297 Story of the Phoenician voyage in the time of Necho 298-300 Voyage of Hanno 300, 301 Voyages of Sataspes and Eudoxus 302 Wild exaggerations 303 Views of Pomponius Mela 304, 305 Ancient theory of the five zones 306, 307 The Inhabited World, or Oecumene, and the Antipodes 308 Curious notions about Taprobane (Ceylon) 309 Question as to the possibility of crossing the torrid zone 309 Notions about sailing "up and down hill" 310, 311 Superstitious fancies 311, 312 Clumsiness of ships in the fifteenth century 312 Dangers from famine and scurvy 313 The mariner's compass; an interesting letter from Brunetto Latini to Guido Cavalcanti 313-315 Calculating latitudes and longitudes 315 Prince Henry the Navigator 316-326 His idea of an ocean route to the Indies, and what it might bring 318 The Sacred Promontory 319 The Madeira and Canary islands 320-322 Gil Eannes passes Cape Bojador 323 Beginning of the modern slave-trade, 1442 323 Papal grant of heathen countries to the Portuguese crown 324, 325 Advance to Sierra Leone 326 Advance to the Hottentot coast 326, 327 Note upon the extent of European acquaintance with savagery and the lower forms of barbarism previous to the fifteenth century 327-329 Effect of the Portuguese discoveries upon the theories of Ptolemy and Mela 329, 330 News of Prester John; Covilham's journey 331 Bartholomew Dias passes the Cape of Good Hope and enters the Indian ocean 332