southward.  According to the mode of navigation, which then prevailed, they held their course along the shore, and by following that direction, they must have encountered almost insuperable difficulties, in the attempt to pass the cape; their want of skill was, however, compensated by a fortunate accident.  A sudden squall drove them out to sea, and when they expected every moment to perish, landed them on an unknown island, which, from their happy escape, they named Porto Santo.  They returned to Portugal with the good tidings, and were received with the applause due to fortunate adventurers.  The following year, prince Henry sent out three ships to take possession of the new island; a fixed spot on the horizon, towards the south, resembling a small black cloud, soon attracted the attention of the settlers, and the conjecture suggested itself that it might be land.  Steering towards it, they arrived at a considerable island, uninhabited, and covered with wood, which, on that account, they called Madeira.

By these voyages, the Portuguese became accustomed to a bolder navigation, and at length, in 1433, Gilianez, one of prince Henry’s captains, by venturing out into the open sea, succeeded in doubling Cape Bojador, which, until then, had been regarded as impassable.  This successful voyage, which the ignorance of the age placed on a level with the most famous exploits recorded in history, opened a new sphere to navigation, as it discovered the vast continent of Africa, still washed by the Atlantic Ocean, and stretching towards the south.  A rapid progress was then made along the shores of the Sehara, and the Portuguese navigators were not long in reaching the fertile regions watered by the Senegal and the Gambia.

The early part of this progress was dreary in the extreme; they saw nothing before them but a wild expanse of lifeless earth and sky, naked rocks and burning sands, stretching immeasurably into the exterior, and affording no encouragement to any project of settlement.  After, however, passing Cape Blanco, the coast began to improve in appearance, and when they saw the ivory and gold brought down from the interior, those regions began to excite the lust of conquest.  This was, however, an undertaking beyond the means of any force which had as yet sailed from Portugal.  In 1443, however, Nuno Tristan discovered the island of Arguin, and as Gonzalo da Centra was in 1445 killed by a party of negroes, in attempting to ascend a small river, near the Rio Grande, the Portuguese considered an insular position to be the most eligible for a settlement, and the island of Arguin was accordingly fixed upon.