The first atlas on Mercator’s Projection from the library of Imperial geographer Wolfgang Engelbert, Earl of Auersperg

First edition of Dudley’s magnificent and very scarce sea atlas, ​‘Dell’Arcano del Mare’ (Secrets of the Sea), complete of all its six parts, which is extremely rare with this edition. The ​‘Arcano de Mare’ is one the ​“greatest atlases of the world” (Wardington).
Dudley first published his magnum opus in 1646 when he 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, all be it abroad in Italy” (Wardington). It was, as argued by Burden, ​“the only exception to the total dominance of Dutch sea atlas production [in the seventeenth century]”.
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. He would later, like all good Tudor seamen, sack Cadiz, an achievement for which he was knighted.
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’.
The atlas is divided into six books, or sections: book one deals with longitude; book two covers errors in the then-existing sea charts, and includes the portolano for the Mediterranean and 15 general maps; book three deals with naval and military discipline, notably the former, and there is a long section on naval tactics, especially remarkable for a plan
of the construction of a navy in five grades of vessel; book four describes the method of designing and building ships of the ​“Galerato” and ​“Galizaba” types and is concerned with naval architecture, giving the lines and dimensions of ships; book five is devoted entirely to navigation and methods of measuring the sun’s declination and the relative positions
of the stars; book six contains the sea atlas.
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. Dudley’s sources included the original charts of Henry Hudson, and for the Pacific coast he used the observations of Henry Cavendish, the third circumnavigator of the globe and Dudley’s brother-in-law. It is also possible that Dudley had access to Henry Hudson’s notes and Sir Francis Drake’s papers, although it is more likely that the important Carta prima Generale d’America was based on the maps of John Daniell, who at the time resided still in Florence.
The 15 maps including in Book Two consist of large-scale maps of the four continents.
The early and possibly original owner of this atlas was the Imperial geographer Wolfgang Engelbert (1610–1673), Earl of Auersperg and between 1649–1673, ruler of the Duchy of Carniola, now in Slovenia. He was author of the Orbis lusus pars prima, seu Lusus geographicus (Graz 1659), Engelbert collected in his palace in Ljubljana a splendid library, highly esteemed by his contemporaries. The library, which contained about 7,000 volumes, was rearranged and catalogued in the mid-nineteenth century by the historian Peter von Radics, who states that the collection ​“is unique in representing the well arranged and well chosen collection, to which no additions have been made, of an Austrian aristocrat of the seventeenth century” (quoted by M. Bircher, The ​“Splendid Library” of the Counts of Auersperg). In 1895 a severe earthquake led to the loss of the Ljubljana castle, but the books were undamaged and transferred along with the family’s archives to Losensteinleithen Castle in Austria. The library eventually descended to family members in Uruguay who sold it by auction in 1982–1983.