[1441-8.] For several years after the successful doubling of Cape Bojador, no new attempt of importance is recorded, but in 1441 the voyages were renewed, and in the next eight years the exploration was pushed one hundred leagues below Cape Verde. Prior to 1446 fifty-one vessels had traded on the African coast, nearly one thousand slaves had been taken to Portugal, and the discoveries in the Azores had been greatly extended. By these explorations Prince Henry had exploded the theory of a burning zone impassable to man, and of stormy seas impeding all navigation; his belief that Africa might be circumnavigated was confirmed; and he had obtained from the pope a grant to the crown of Portugal of lands he might discover beyond Cape Bojador to the Indies inclusive. [1455-6.] According to Ramusio, _Viaggi_, tom. i. p. 105, Alvise Cadamosto, a Venetian, the first of his countrymen as he claims to sail down the new coast, made a voyage for Prince Henry to the Gambia River below Cape Verde. This expedition derives its importance not from the limit reached, where others had preceded him, but from his numerous landing points, careful observations, and the detailed account published by the voyager himself in _La Prima Navigazione, etc._, Vicenza, 1507; also in _Ramusio_, _Viaggi_, tom. i. pp. 104-15. This explorer touched at Porto Santo, Madeira, the Canaries, Cape Blanco, Senegal, Budomel, Cape Verde, and the Gambia River. [1457.] Cadamosto claims, _La seconda navigazione_, in _Ramusio_, _Viaggi_, tom. i. pp. 116-20, to have made a second voyage, during which he discovered the Cape Verde Islands; but Major, _Prince Henry_, pp. 278-88, shows that such a voyage was not made in that year, if at all. [1460.] Diogo Gomez discovered the Cape Verde Islands, and their colonization was effected during the following years. Major, _Prince Henry_, pp. 288-99, publishes the original account for the first time in English. Prince Henry died in November of this year. _Major's Prince Henry_, p. 303; _Kunstmann_, _Entdeckung Am._, p. 19. Irving, _Columbus_, vol. i. p. 30, fixes this date 1473; and Galvano, _Discov._, p. 14, says 1463. [1461.] The spirit of discovery and the thirst for African gold and slaves had become too strong to receive more than a temporary check in the death of its chief promoter. In the year following Prince Henry's death a fort was built on the African coast to protect the already extensive trade, and in 1461 or 1462 Pedro de Cintra reached a point in nearly 5° north, being over six hundred miles below the limit of Cadamosto's voyage. _La Nauigation del Capitan Pietro di Sintra Portoghese, scritta per Meser Aluise da ca da Mosto_, in _Ramusio_, tom. i. fol. 119.