52 THE QUEST FOR INDIA BY SEA plorations (1418 - 1460) added only eighteen degrees of latitude to the verified geography of the northwestern African coast, from Cape Bojador to Sierra Leone, or not four days' course of a steamship in our times. He barely penetrated the edge of the vast Sea of Darkness. This small result from so much toil and devotion was due in part to the poor sailing qualities of his vessels, in part to the imperfections of his nautical instruments and to the rudimentary state of navigating science. The fleets of the Mediterranean had largely consisted of galleys propelled by slaves. But oars could ill contend with the mighty waves of the Atlantic, nor was it possible to provide food for hundreds of rowers on the long voyages which Prince Henry planned. His first problem was to develop the oared galley or weak sailing craft of an inland sea into the ocean-going ship, and to supersede the thews of men with hungry mouths by the winds which ate nothing. The question of sails versus oars dates from the earliest period of navigation, and has been discussed by the latest naval historians. Prince Henry required not only a new type of vessel but also a new adaptation of an old force to propel it. It was the Atlantic as against the Mediterranean, and the sailing ship as against the slave-rowed galley. In this task, as in his actual discoveries, Prince Henry had predecessors. Contemporary drawings dis- close the transition from the mediasval galley, a sort of beaked barge with upper structures for fighting men and the lower deck crammed with rowers, to the heavy galleon and galleasse, and the handier caravel with its
