CAM (CAO), DIOGO (fl. 1480-1486)  , Portuguese discoverer, the first European known to sight and enter the Congo, and to explore the West African coast between Cape St Catherine (2° S.) and Cape Cross (21° 50' S.) almost from the equator to Walfish Bay . When King John II. of Portugal revived the work of Henry the Navigator, he sent out Cam (about midsummer (?) 1482) to open up the African coast still further beyond the equator . The mouth of the Congo was now, discovered (perhaps in August 1482), and marked by a stone pillar (still existing, but only in fragments) erected on Shark Point; the great river was also ascended for a short distance, and intercourse was opened with the natives . Cam then coasted down along the present Angola (Portuguese West Africa), and erected a second pillar, probably marking the termination of this voyage, at Cape Santa Maria (the Monte Negro of these first visitors) in 13° 26' S . He certainly returned to Lisbon by the beginning of April 1484, when John II. ennobled him, made him a cavalleiro of his house-hold (he was already an escudeiro or esquire in the same), and granted him an annuity and a coat of arms (8th and 14th of April 1484) . That Cam, on his second voyage of 148g-1486, was accompanied by Martin Behaim (as alleged on the latter's Nuremberg globe of 1492) is very doubtful; but we know that the explorer revisited the Congo and erected two more pillars beyond the furthest of his previous voyage, the first at another " Monte Negro " in 15° 41' S., the second at Cape Cross in 21° 50', this last probably marking the end of his progress southward . According to one authority (a legend on the 1489 map of'Henricus Martellus Germanus), Cam died off Cape Cross; but Joao de Barros and others make him return to the Congo,and take thence a native envoy to Portugal . The four pillars set up by Cam on his two voyages have all been discovered in situ, and the inscriptions on two of them from Cape Santa Maria and Cape Cross, dated 1482 and 1485 respectively, are still to be read and have been printed; the Cape Cross padrao is now at Kiel (replaced on the spot by a granite facsimile); those from the Congo estuary and the more southerly Monte Negro are in the Museum of the Lisbon Geographical Society . See Barros, Decades da Asia, Decade i. bk. iii., esp. ch . 3; Ruy de Pina, Chronica d' el Rei D . Joao II . ; Garcia de Resende, Chronica; Luciano Cordeiro, " Diogo Cao " in Boletim of the Lisbon Geog .

Soc., 1892; E . G . Ravenstein, "Voyages of Diogo Cao," &c., in Geog . Al. vol. xvi . (1900); also Geog . Jnl. xxxi . (1908) . (C . R .