In Ulysses’s boat, therefore, we see for the first time a combination of structural features and propelling agents that compare, remotely though it may be, with ships as they are to-day. A built-up structure with a framework, propelled by sails—it was an early counterpart of the ships of the present time. Naturally enough this development did not take place simultaneously in all parts of the world. The most advanced civilizations such as those of Phœnicia, Greece, and China developed the most advanced ship-building methods, just as they developed the most advanced arts and sciences and thought and religion. For instance, when Columbus discovered America a vital factor in the development of ships was entirely unknown to the natives that he found. No Indian tribe with which he or later explorers came in contact had learned the use of sails to propel the canoes they almost universally used. Civilizations of surprising worth, with art and architecture in high stages of advancement, had existed and had practically disappeared in Yucatan and Central America, and other civilizations of genuine attainment were later found, by Cortes and Pizarro, in Mexico and Peru, yet none of them knew the uses of the sail. On the other hand, the Egyptians and the Phœnicians used the sail, and twenty-five centuries before the discovery of America the Phœnicians are thought to have sailed their ships around the continent of Africa from the Red Sea to the Mediterranean. But while the art of ship-building progressed more rapidly after the development of the use of wooden pegs for fastenings, and the use of sails and oars made possible more extended sea journeys, still the development was slow, and until the discovery of the power of steam in the latter part of the 18th Century no revolutionary changes in ships took place. Just when the method originated of first constructing the frame of the ship and of covering this frame with planks, we do not know, but the transition from the method in use at the time of Homer was simple and the change was probably gradual. [Illustration: A PERUVIAN BALSA _These “boats” are really rafts made of reeds._] It seems possible that the built-up boat may have had its origin in the attempt of some savage to raise the sides of his dugout canoe by the addition of boards in order to keep the water from harming his goods. But all of the history of boats up to the time of written history is necessarily mostly surmise.