The discovery in olden times of the attractive properties of a fragment of iron ore, was the basis of the invention of the mariner's compass, which greatly improved navigation, and led to nearly all the chief maritime discoveries which have since been made. The sciences of magnetism and geometry form the basis of the art of navigation, and have thus made our great foreign commerce possible. The discovery of magnetism enabled sailing vessels to venture freely out of sight of land, and to traverse the wide ocean with even greater safety than to sail near the shore. By its means Columbus crossed the Atlantic Ocean and discovered America. By its {14} means also, Vasco de Gama sailed round the Cape of Good Hope and discovered a new route to India; and in the year 1500, another Portuguese Captain, Cabral, was driven across the Atlantic, discovered Brazil, and was enabled by the aid of the magnet, to send back a ship to Lisbon with news of the discovery. By its assistance also Magellan discovered Patagonia and the South Pacific Ocean; and by the completion of that voyage the Earth was first circumnavigated and proved to be a globe. The geographical discoveries of the Portuguese, made by means of the magnet, produced great national results; they profoundly changed the balance of power and wealth among European nations, by changing the direction of navigation and of the great streams of commerce between Europe and the East. They gave a mortal blow to Italy and the cities of the Mediterranean, by transferring Eastern commerce to Spain and Portugal: and Egypt ceased to be the greatest route of commerce from Europe to India. A singular contract relating to geographical research was made in the fifteenth century, between King Alphonso, of Portugal, and Ferdinand Gomez, of Lisbon, by which the latter engaged to navigate a ship and explore the coast of Africa, and to discover not less than three hundred miles of coast every year, the measurement to be made from Sierra Leone. {15} Scientific discovery has in all ages been a most powerful agent of civilization and human progress. The discovery of the black liquid which a solution of nutgalls produces when mixed with green vitriol, led to the invention of writing ink; and a knowledge of the properties of ink and paper prepared the way for the invention of printing, by means of which truth and learning have spread all over the earth.