It had hitherto been customary for Portuguese navigators to erect wooden crosses upon all lands discovered by them. John II. now commanded them to employ stone pillars six feet high, and to inscribe upon them, in the Latin and Portuguese languages, the date, the name of the reigning monarch, and that of the discoverer. Diego Cam was the first to comply with this command; he set up a column at the mouth of the river Congo, at which he arrived in 1484. An ambassador was sent by the chief of the territory to Portugal, where he embraced Christianity and was baptized by the name of John. The anxiety of the king now increased in reference to interference by other nations: he therefore sent to King Edward, of England, an earnest request that he would prevent the intended voyage to Guinea of two of his subjects, John Tintam and William Fabian, with which request Edward saw fit to comply. The Portuguese monarch now carefully concealed the progress of his navigators upon the African coast, and on all occasions magnified the perils of a Congo voyage. He declared that every quarter of the moon produced a tempest; that the shores were girt with inhospitable rocks; that the inhabitants were cannibals, and that the only vessels which could live in the waters of the torrid zone were caravels of Portuguese build. Suspecting that three sailors who had left Portugal for Spain intended to sell the secret to the foreign king, he ordered them to be pursued and taken. Two were killed, and the third was broken upon the wheel. "Let every man abide in his element:" said John; "I am not partial to travelling seamen."