The gilt supra-libros resemble those tentatively attributed to Gian Carlo de’Medici in the exhibition catalogue for the Biblioteca Universittaria de Pisa’s ‘Medicea Volvmina: Legature e libri dei Medici’ (2001, item 57). In its entirety, the binding closely matches that on the first edition of the ‘Dell’Arcano del Mare’ at the Bodleian Library in Oxford, which bears the arms of Cosimo III de’Medici; and that at the John Carter Brown library in Providence, which bears the alliance arms of the Medici and della Rovere families. Each is bound in the same style, using the same morocco, the same gilt tools, and in the case of the Bodleian example, the same endpapers; strongly suggesting that they were commissioned by 

 of the same binder at the same time for presentation to his patrons.

Volume I

Volume II

Volume III

Volume IV

Published in four volumes, The ‘Dell’Arcano del Mare’, represents a compendium of contemporary navigational knowledge and was pioneering in a number of ways: it was the earliest printed sea atlas to cover the entire world; the first compiled by an Englishman; and the first to base its charts on the map projections used by 

. Equally remarkable was the fact that it was written in the Italian language by 

 himself; that the maps were all his own; and that, in the first edition, many of the charts have movable parts (‘volvelles’).

The range of topics covered is also impressive, from navigational matters, including longitude and astronomical aids, to shipbuilding and naval and military discipline. The work includes a proposal for constructing a navy in five rates, designed and described by the author with the use of engravings, the featured image (from volume II) demonstrating the most effective way of firing a canon from a naval vessel. The sea atlas contains both general ocean charts and detailed surveys which not only delineate world coastlines but also show prevailing winds, currents, and magnetic deviation.

For the 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 5,000 pounds 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 Hudson’s notes and 

’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 in Florence.

 (1573–1649) was an English explorer and cartographer who published his ‘Dell’Arcano del Mare’ (‘Secrets of the Sea’) in 1646 when he was seventy-three years old. It was the culmination of his life’s work as a mariner, and its Italian title and dedication to Ferdinand II de ’Medici is a testament to his close bond to the Medici family dynasty. 

The illegitimate son of Lord 

, Earl of Leicester and Lady Douglas Sheffield, Dudley developed a fascination with charts and instruments at an early age, and in 1594 he set out on a voyage of discovery to Trinidad and the Guiana coast. His subsequent participation in naval operations against Spain led him to be knighted two years later by the Queen but as he could not prove his legitimacy or claim his father’s and uncle’s titles in the English courts, he exiled himself to Italy in 1605. There he entered the service of Ferdinand I and his successor as Grand Duke of Tuscany, Cosimo II, as naval advisor and engineer, building up a modern Tuscan navy, constructing a state-of-the-art harbour at Livorno and draining the marshes between Pisa and Livorno before his death in Italy in 1649.

’s magnum opus. The magnificent and very scarce sea atlas, ‘Dell’Arcano del Mare’ (‘Secrets of the Sea’) was revolutionary in its time: it was the first sea atlas of the world; the first to use 

’s projection; the earliest to show magnetic deviation; the first to show currents and prevailing winds; and the first to expound the advantages of ‘Great Circle Sailing’ (i.e. the shortest distance between two points on a globe). Created near the end of Dudley’s life, the atlas represents a culmination of the cartographer’s extensive knowledge and experience. It was published while Dudley was abroad in Italy (hence the Italian title); this example is one of a few bound specially for members of the Medici family.

’s magnum opus.  The magnificent and very scarce sea atlas, ‘Dell’Arcano del Mare’ - Secrets of the Sea - is one the “greatest atlases of the world” (Wardington): it is the first sea atlas of the world; 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”. This example, one of a few bound specially for members of the Medici family.

Bound in superb contemporary panelled brown morocco gilt with the ecclesiastical supra-libros of a cardinal of the Medici family, almost certainly Gian Carlo de’ Medici (1611-1663). Carlo de' Medici was appointed 'High Admiral of the Tuscan Navy' in 1638, held the title of 'General of the Mediterranean Sea', and was made 'General of the Spanish Seas' by Philip IV of Spain during the Forty Years' War, before became a reluctant Cardinal from 1644. 

6 parts in 4 volumes. Folio. Complete with half-titles, vignette title-pages, and 146 finely engraved maps, 218 plates and all original moveable parts.

Dudley's Sea Charts and Atlas, in 4 volumes