HERNANDO DE

ALARCON  , Spanish navigator of the 16th century, is known only in connexion with the expedition to the coast of California, of which he was leader . He set sail on the 9th of May 1540 with orders from the Spanish court to await at a certain point on the coast the arrival of an expedition by land under the command of Vasquez de Coronado . The junction was not effected, though Alarcon reached the appointed place and left letters, which were afterwards found by Diaz, another explorer . Alarcon was the first to determine with certainty that California was a peninsula and not an island, as had been supposed . He made a careful survey of the coast, ascended the Rio del Tizon or Rio de Buena Guia (Colorado) for 85 Spanish m., and was thus able on his return to New Spain in 1541 to construct an excellent map of California . See Herrera, Decade VI. book ix. ch . 15; vol. vi. fol . 212 of Madrid edition of 1730 .