The first atlas on Mercator’s Projection

By DUDLEY, Robert, 1646 

Dell’arcano del mare di D. Ruberto Dudleo duca di Nortumbria, e conte di VVarvich, libri sei…

  • Author: DUDLEY, Robert
  • Publication place: Florence
  • Publisher: Francesco Onofri
  • Publication date: 1646–1647.
  • Physical description: 6 parts in 2 volumes, folio (570 by 480mm). Complete with half-titles, vignette title-pages, and 146 finely engraved maps, 218 plates and all original moveable parts, volume 1 second edition, volume 2 first edition.Volume IBook 1. [4], [2], 30pp., illustration: printed title with plate of a navigational instrument pasted on, engraved facsimile of the Patent, 30 engravings on 27 sheets, 22 of which have moveable volvelles, 2 plates cut to neatline and laid down.Book 2. 24pp., illustration: 15 engravings on 9 sheets, 5 of which have volvelles and 15 large (6 double-page or folding) engraved charts, 4 relating to America, 5 of the European coasts, 4 of Asia, and 2 of Africa, 1 plate cut to neatline and laid down, folding maps with some discolouration.Book 3. 25, [1]pp., illustration: 8 engraved plates on 6 sheets (3 plates being of ships in battle formation etc.) and 4 sheets with plates of fortifications and cities with walled defences.Book 4. 12pp., illustration: 18 engravings on 14 sheets (of which 7 are double-page and one has a volvelle) all designs of ships in plan and in section, 2 sheets with engravings cut to neatlines and laid down.Book 5. 26, [2]pp., illustration: 145 engravings on 89 sheets, 38 and have moveable volvelles, 15 sheets with plates cut to neatline and laid down,.Volume IIBook 6. [2 (printed title with vignette of the great bear)], 60, [2 (“Discorso delle Scienze Mathematiche” dated 1648)] pp., illustration: 131 engraved charts (82 double-page), 58 covering Europe, Greenland and Canada , 17 of Africa, 23 of Asia and 33 of America.Contemporary calf over boards, red morocco label to spine, gilt.
  • Inventory reference: 18464


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”.

The Arcano del Mare’.
Dudley’s sea 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 Thomas 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 included in Book Two consist of large-scale maps of the four continents.

Complete examples of the first edition of Dudley’s Dell’arcano del mare’ are extremely scarce. Only 10 complete institutional examples are known, at: the Bodleian; the Bibliotheque nationale de France; the British Library; the National Library, Florence; the Lilly Library, Indiana; John Carter Brown library, Providence; Leiden; Library of Congress; Newberry Library, Chicago; Newcastle University Robinson Library. Only three of these appear to be in contemporary bindings. 


Bookplates of the Earls of Macclesfield from the South Library on the front paste-down dated 1860. 


  1. Phillips, Atlases 457
    • Phillips, P. (1909–1992). A list of goegrpahical atlases in the Library of Congress. Washington: Govt. Print. Off.
  2. cf. Shirley, BL, M.DUD-1a–1e. Burden 266–267
    • Shirley, Rodney. (2004). Maps in the Atlases of the British Library: A descriptive catalogue cAD850 to 1800. London: British Library. 2 vols.
  3. Nordenskiöld 70
  4. M. Bircher, The Splendid Library” of the Counts of Auersperg in Ljubljana, in The German Book, 1450–1750, ed. by J. Flood and W.A. Kelly, London 1995, pp. 285–98
  5. Lord Wardington, Sir Robert Dudley and the Arcano del Mare’, The Book Collector 52 (2003), pp.199–211
  6. John Temple Leader, Life of Robert Dudley’, Florence, 1895, reprinted Amsterdam, 1970.

Image gallery