DUDLEY, Sir Robert, as he was called in England, and, as he was styled abroad, Earl of Warwick and Duke of Northumberland, was the son of Robert above mentioned, by the Lady Douglas Sheffield, and was born at Sheen, Surrey, in 1573. On his father's death, in 1588, he succeeded to the greater part of the patrimonial estate; and being fond of navigation, he fitted out a small squadron at his own expense, with which he sailed to the river Orinoco, and took and destroyed nine sail of Spanish ships. In 1595 he attended the Earl of Essex and the lord high admiral of England in their expedition against the Spaniards; and for his gallant behaviour at the taking of Cadiz he received the honour of knighthood. He now endeavoured to prove the legitimacy of his birth, in order to be entitled to his hereditary honours. But being overpowered by the interest of the Countess Dowager of Leicester, he retired to the court of Florence, where he was well received; and on his refusal to return to England his whole estate was seized by King James I. and vested in the crown. At the court of Cosmo II. grand duke of Tuscany, he acquired considerable influence, and enjoyed distinguished honours. For improvements in shipping and manufactures which he projected, as well as for other services, the Emperor Ferdinand, in 1620, created him a duke of the holy Roman empire. He afterwards drained a vast tract of morass between Pisa and the sea, and raised Leghorn, which was then a mean and insignificant place, into a large and beautiful town, improving the haven, and by his influence drawing many English merchants to settle there. He was also a zealous patron of literature, and held a place in the republic of letters. His most celebrated work is his Del Arcano del Mare, Firenze, 1630, 1646, folio. This work, which has always been scarce, has now become extremely rare. There is a copy in the British Museum, dated 1661, called the second edition; but that which we have seen belongs to the Society of Writers to the Signet, Edinburgh. The work, which consists of a collection of tracts, comprehends a great number of projects for the improvement of navigation and commerce, with the charts and plans relating to the subject; all of them schemes which, considering the time when they were devised, are quite remarkable for the boldness and originality with which they are conceived, and the extent of scientific acquirements which they exhibit. Sir Robert Dudley died at his castle of Carbello, near Florence, in 1639.