Navigational volvelle 

Machinery illustration

Instrument design

Moveable volvelle

Projected drawing, declining plane

Ornamental navigational tool stand design

Surveying instrument design

Moveable volvelle for calculations

Coordinates, latitude and longitude instrument 

Altitude volvelle 

Handheld compass designs

Map of the Atlantic Ocean around the  north African coast

Map of the Atlantic Ocean between Africa and America 

The Isthmus of Panama map

Map of South America 

Map of the 'East Sea'

Map of the Indian Ocean 

Map of Japan

Third map of Asia

Map of the North Western coast of North America 

4th map of Europe

Map of the English Channel 

map of the Scottish Ocean

Map of the oceans in Scandinavia 

The binding includes the ecclesiastical supra-libros of a cardinal of the Medici family, almost certainly Gian Carlo de’ Medici (1611–1663), who was the 'High Admiral of the Tuscan Navy' in 1638, the 'General of the Mediterranean Sea', and made 'General of the Spanish Seas' by Philip IV of Spain during the Forty Years' War, before he reluctantly became Cardinal from 1644. 

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

The maps in this magnificent atlas are all of Dudley's own design – first edition copies include charts with movable parts (‘volvelles’). 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. The information in the charts was compiled by 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. For the Pacific Coast, he used the observations of Henry Cavendish (observed c. 1587), 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 (c.1646).

Folio. Six parts in four volumes. Complete with half-titles; vignette title pages; 218 total plates; 146 finely engraved maps; at least 150 illustrations; 156 folding-plates; all original volvelles. There are 132 maps in Part Six including fifty-nine of Europe, seventeen of Africa, twenty-three of Asia and thirty-three of America, of which eighty are double-page.

This magnificent and very scarce sea atlas, ‘Dell’Arcano del Mare’ (‘The 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). Equally remarkable was the fact that it was written in the Italian language by 

 himself, who was English. 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), and is one of a few bound specially for members of the Medici family. 

There are a total of 146 engraved maps and ninety moveable volvelles, all original. For the engraved charts, Dudley employed the services of Antonio Francesco Lucini, who states in the atlas that the work took him twelve years to complete and required 5,000 pounds of copper.

Published in four volumes, ‘The Secrets of the Sea’, is a compendium of contemporary navigational knowledge. The atlas covers topics ranging from navigational matters, including longitude and astronomical aids, to shipbuilding and naval and military discipline. The work also 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.

’s magnum opus: 'Dell’Arcano del Mare' ('Secrets of the Sea'). The first sea-atlas to: use Mercator’s projection, to show magnetic deviation, show currents and prevailing winds, expound the advantages of 'Great Circle Sailing' (the shortest distance between two points on a globe). Also the first sea-atlas to be compiled by an Englishman, though he lived in Italy during its composition. This example, one of a few bound specially for members of the Medici family.

Bound in 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).