The map shows Central America and the Caribbean Sea with Cuba, Hispaniola, the Bahamas, Jamaica and the Cayman Islands. California is still shown as an island on the left. The inset shows the northern coastline with a large bay between Cape Engano and C. di Cedros. The extent of the bay, marked Golfo Profoundo, is suggested with dotted lines with an inscription noting “This gulf has recently been reported as very large but has not been well explored.” The Golfo Profoundo may well have been spotted by Martin d’Aguilar on Vizcaino’s voyage, leading him to believe that California was an island.

P. di Moneerei (Monterey Bay) and P. di S. Diego (San Diego), two towns discovered and named by Vizcaino, are marked by anchor symbols on the southern coast. The accuracy of their name and location indicates that Dudley had access to the official account of Vizcaino’s voyage, which was not published until 1802. Point New Albion is marked with a note of its discovery by Francis Drake, and Northern California is marked by the name Drake gave it, Nuova Albione. Quivira R (Kingdom of Quivira) is marked on the left of the inset. Quivira was supposedly a hidden but colossally wealthy Native American kingdom, rich in gold and silver. The 1540 Coronado Expedition found it “950 leagues from Mexico”. Unfortunately, it contained no precious metals, just very fertile country.

From the ‘Arcano de Mare’, one the “greatest atlases of the world” (Wardington). First published in 1646 when its author, Robert Dudley, was 73, it was not only the first sea atlas of the world, but also the first to use Mercator’s projection; the earliest to show magnetic deviation; the first to show currents and prevailing winds; the first to expound the advantages of ‘Great Circle Sailing’ – the shortest distance between two points on a globe; and “perhaps less importantly the first sea-atlas to be compiled by an Englishman, albeit abroad in Italy” (Wardington).

Robert Dudley (1573–1649) was the son of the Earl of Leicester (the one time favourite of Elizabeth I) and Lady Douglas Sheffield, the widow of Lord Sheffield. Although born out of wedlock, Robert received the education and privileges of a Tudor nobleman. He seems to have been interested in naval matters from an early age, and in 1594, at the age of 21, he led an expedition to the Orinoco River and Guiana. His success upon the high-seas was not matched, unfortunately, by his luck at court, and at the beginning of the seventeenth century he was forced to flee, along with his cousin Elizabeth Southwell, to Europe. Eventually he ended up in Florence at the court of Grand Duke Ferdinand I of Tuscany, where he not only married his cousin and converted to Catholicism, but also help Ferdinand wage war against the Mediterranean pirates. In his spare time he set about his great life’s work: the ‘Arcano del Mare’.

For the beautifully engraved charts, Dudley employed the services of Antonio Francesco Lucini. Lucini states in the atlases that the work took him 12 years to complete and required 5,000lbs of copper. The charts are by English and other pilots, and it is generally accepted that the work was both scientific and accurate for the time. It is assumed that Dudley used the original charts of Henry Hudson, and for the Pacific Coast of America used his brother in-law Thomas Cavendish’s observations.