Diogo Cam, a Portuguese navigator, born in the second half of the 15th century, died toward the beginning of the 16th. He passed Cape Lopo Goncalvez and Cape Catharina, on the coast of Africa, and placed on the southern shores of the Congo river a pedrdo, or pile of stones, which henceforward served as boundary between the territories explored and those still unknown. He was the first to put himself into personal contact with the population of Congo, and leaving a few Portuguese sailors as hostages behind, he took some of the natives with him to Lisbon. This expedition, which took place in 1484, became of still greater service to science by the astronomical observations of the learned Martin Behaim, who accompanied it. Cam returned to Congo within 15 months, in accordance with a promise which he had made to the natives who went with him to Lisbon, and planted a second pedrao in lat. 13° S. He penetrated as far as lat. 22°, and on making his appearance at the court of the black king of Congo, he was received with every demonstration of cordiality, and the king sent an ambassador, Cazuta, with presents to Lisbon.