Geography and World Power, James Fairgrieve, 1917.
CHAPTER VI
OPENING THE OCEAN ROUTES
1. PORTUGAL AND THE NEW ROUTE TO INDIA
From the days of the Phœnicians to the close of the 15th century, all trade between Europe and Asia crossed the land barrier east of the Mediterranean. Delivered by Mohammedan vessels at the head of the Persian Gulf or the ports of the Red Sea, merchandise followed thence the caravan routes across Arabia or Egypt to the Mediterranean, quadrupling in value in the transit. Intercourse between East and West, active under the Romans, was again stimulated by the crusades and by Venetian traders, until in the 14th and the 15th centuries the dyes, spices, perfumes, cottons, muslins, silks, and jewels of the Orient were in demand throughout the western world. This assurance of a ready market and large profits, combined with the capture of Constantinople by the Turks (1453), their piratical attacks in the Mediterranean which continued unchecked until Lepanto, and their final barring of all trade routes through the Levant, revived among nations of western Europe the old legends of all-water routes to Asia, either around Africa or directly westward across the unknown sea.
With the opening of ocean routes and the discovery of America, a rivalry in world trade and colonial expansion set in which has continued increasingly down to the present time, forming a dominant element in the foreign policies of maritime nations and a primary motive for the possession and use of navies. The development of overseas trade, involving the factors of merchant shipping, navies, and control of the seas, is thus an integral part of the history of sea power. The great voyages of discovery are also not to be disregarded, supplying as they did the basis for colonial claims, and illustrating at the same time the progress of nautical science and geographical knowledge.
| CROSS-STAFF |
The art of navigation, though still crude, had by the 15th century so advanced that the sailor was no longer compelled to skirt the shore, with only rare ventures across open stretches of sea. The use of the compass, originating in China, had been learned from the Arabs by the crusaders, and is first mentioned in Europe towards the close of the 12th century. An Italian in England, describing a visit to the philosopher Roger Bacon in 1258, writes as follows: "Among other things he showed me an ugly black stone called a magnet ... upon which, if a needle be rubbed and afterward fastened to a straw so that it shall float upon the water, the needle will instantly turn toward the pole-star; though the night be never so dark, yet shall the mariner be able by the help of this needle to steer his course aright. But no master-mariner," he adds, "dares to use it lest he should fall under the imputation of being a magician."[1] By the end of the 13th century the compass was coming into general use; and when Columbus sailed he had an instrument divided as in later times into 360 degrees and 32 points, as well as a quadrant, sea-astrolabe, and other nautical devices. The astrolabe, an instrument for determining latitude by measuring the altitude of the sun or other heavenly body, was suspended from the finger by a ring and held upright at noon till the shadow of the sun passed the sights. The cross-staff, more frequently used for the same purpose by sailors of the time, was a simpler affair less affected by the ship's roll; it was held with the lower end of the cross-piece level with the horizon and the upper adjusted to a point on a line between the eye of the observer and the sun at the zenith. By these various means the sailor could steer a fixed course and determine latitude. He had, however, as yet no trustworthy means of reckoning longitude and no accurate gauge of distance traveled. The log-line was not invented until the 17th century, and accurate chronometers for determining longitude did not come into use until still later. A common practice of navigators, adopted by Columbus, was to steer first north or south along the coast and then due west on the parallel thought to lead to the destination sought.
[Footnote 1: Dante's tutor Brunetto Latini, quoted in The Discovery of America, Fiske, Vol. I, p. 314.]
| THE KNOWN AND UNKNOWN WORLD IN 1450, SHOWING THE VOYAGES OF COLUMBUS, VASCO DE GAMA, MAGELLAN, AND DRAKE |