{{Short description|Nautical charts, first made in the 13th century}} [[File:Mediterranean chart fourteenth century2.jpg|upright=1.3|thumb|A portolan [[nautical chart]] of the [[Mediterranean Sea]], second quarter of the 14th century. Kept in the [[Library of Congress]], where it is the oldest original cartographic artifact.]]'''Portolan charts''' are the earliest known type of [[nautical chart]]s, and the oldest known examples were made in the late 13th and early 14th centuries in the [[Mediterranean Sea|Mediterranean]] region, usually displaying the areas between the [[Atlantic Ocean|Atlantic]] coasts of Western Europe and Northwestern Africa to the west and the [[Black Sea]] to the east. Besides those showing the entire area on a single map field, there are also portolan charts that show smaller territorial extents, either as separate editions or as a series of charts that together form [[Atlas|portolan atlases]].
The word ''portolan'' comes from the [[Italian language|Italian]] ''portolano'', meaning "related to [[port]]s or [[harbours|harbors]]", and which since at least the 17th century designates "a collection of sailing directions".<ref>{{cite web |last1=Campbell |first1=Tony |title='Portolan charts from the late thirteenth century to 1500' (Additions, Corrections, Updates) |url=http://www.maphistory.info/portolanchapter.html#terminology |access-date=8 December 2018 |website=Map History / History of Cartography: THE Gateway to the Subject}}</ref>
Portolan charts are manuscript charts rendered using ink on [[vellum]] sheets and are easily recognizable by their distinct visual characteristics, such as a content focus on coastal regions, networks of colour-coded straight lines emanating from one or more centres in 32 directions, [[Linear scale|linear scale bars]] calibrated in so-called ''portolan miles'' (''miglio''),<ref name=":0" /> and [[Toponymy|place names]] inscribed perpendicular to the coastline contours. Their most perplexing features are the extremely realistic portrayal of coastlines and a complete historical lack of their evolutionary path<ref name=":1" /> because the oldest known samples have already been made to a highly developed stage,<ref>{{Cite journal |last=Marelić |first=Tome |date=2024-06-01 |title=Traces of the Common Origin of Carte Pisane, Cortona Chart, and Pietro Vesconte's Charts |url=https://doi.org/10.1007/s42489-023-00154-6 |journal=KN - Journal of Cartography and Geographic Information |language=en |volume=74 |issue=2 |pages=137–156 |doi=10.1007/s42489-023-00154-6 |bibcode=2024JCGI...74..137M |issn=2524-4965|url-access=subscription }}</ref><ref name=":2">{{Cite journal |last=Marelić |first=Tome |date=2024-12-18 |title=Are Portolan Charts and Portolan Mile Geometrically Rooted in Classical Antiquity? A Cartometric Analysis of al-Shirazi's "Greek Map" and the Pisane, Lucca, Avignon, and Cortona Charts |url=https://utppublishing.com/doi/10.3138/cart-2024-0029 |journal=Cartographica |volume=59 |issue=4 |pages=143–160 |doi=10.3138/cart-2024-0029 |issn=0317-7173|url-access=subscription }}</ref> and later-made charts and atlases have not become more accurate over time.<ref name=":3">{{Cite journal |last=Marelić |first=Tome |title=Copying-lineages of portolan chart metrics and implications of their pre-medieval origin |url=https://doi.org/10.1080/23729333.2024.2349974 |journal=International Journal of Cartography |date=2024 |volume=0 |pages=1–26 |doi=10.1080/23729333.2024.2349974 |issn=2372-9333|url-access=subscription }}</ref><ref name=":4">{{Cite journal |last=Marelić |first=Tome |date=2025-03-01 |title=Mosaics Within Mosaics: The Geometry of Portolan Atlases that Contradicts the Medieval Origin Hypothesis |url=https://doi.org/10.1007/s42489-024-00176-8 |journal=KN - Journal of Cartography and Geographic Information |language=en |volume=75 |issue=1 |pages=57–78 |doi=10.1007/s42489-024-00176-8 |bibcode=2025JCGI...75...57M |issn=2524-4965|url-access=subscription }}</ref>
== Terminology == The term "portolan chart" was coined in the 1890s because at the time it was assumed that these maps were related to [[portolani]], medieval or early modern books of sailing directions.<ref>Campbell 1987, page 375</ref> Other names that have been proposed include "[[rhumb line]] charts", "compass charts" or "[[loxodromic navigation|loxodromic]] charts"<ref name=":1">{{Cite book|title=The enigma of the origin of Portolan charts : a geodetic analysis of the hypothesis of a medieval origin|last=Roel|first=Nicolai|year=2016|isbn=9789004282971|location=Leiden|pages=11–12|oclc=932069190}}</ref> whereas modern French scholars prefer to call them just "nautical charts" to avoid any relationship with portolani.<ref>{{cite book |last1=Vagnon |first1=Emmanuelle |editor1-last=Gautier Dalché |editor1-first=Patrick |title=La Terre connaissance, représentations, mesure au Moyen Âge |date=2013 |publisher=Brepols |isbn=978-2-503-54753-4 |language=fr |chapter=La représentation cartographique de l'espace maritime}}</ref>
Several definitions of portolan chart coexist in the literature. A narrow definition includes only medieval<ref>For example, Ramon Pujades only considers charts earlier than 1470 in his census.{{cite book |last1=Pujades i Bataller |first1=Ramon Josep |title=Les cartes portolanes: la representació medieval d'una mar solcada |date=2007 |publisher=Institut Cartogràfic de Catalunya, l’Institut d’Estudis Catalans i l’Institut Europeu de la Mediterrània |isbn=978-84-393-7576-0}}</ref> or, at the latest, early modern [[Nautical chart|sea charts]] (i.e. those that primarily focus on sea basins and coastlines, leaving the depictions of inland areas with little or no content) that include a [[Rhumbline network|network of rhumb lines]] and do not show any indication of the use of spherical coordinates, i.e. [[latitude]]s and [[longitude]]s .<ref name=Gaspar2013/> The geographic extent of these mostly medieval portolan charts is limited to the Mediterranean and Black Seas with possible extensions to West European coasts up to Scandinavia and West African coasts down to Guinea. Some authors further restrict the term "portolan chart" to single-sheet maps drawn on parchment,<ref>{{cite conference |url=https://www.academia.edu/37273410 |title=Emergent Maps: Questioning the Rise and Function of the Portolan Chart and the Regional Map in the Middle Ages |last1=Delano-Smith |first1=Catherine |date=7–8 June 2018 |location=Lisbon |conference=Second International Workshop on the Origin and Evolution of Portolan Charts }}</ref> whereas late medieval and early modern manuscript bindings that contain several nautical charts are usually called "nautical atlases" or "portolan [[atlas]]es". A broader definition of portolan chart includes any manuscript nautical chart or atlas that primarily depicts coastal areas, contains a network of rhumb lines, and has place names written perpendicularly to the coastline.<ref>{{cite book |last1=Pflederer |first1=Richard |title=Census of Portolan Charts and Atlases |date=2009 |publisher=Privately printed}}</ref><ref>{{cite web |last1=Campbell |first1=Tony |title=Cartographic innovations by the early portolan chartmakers |url=http://www.maphistory.info/PortolanChartInnovations.html |website=Map History / History of Cartography: THE Gateway to the Subject |access-date=8 December 2018 |date=18 November 2016}}</ref> This expanded definition encompasses charts of virtually any sea area and even maps of the entire world, often referred to as [[nautical planisphere]]s, as long as they satisfy the aforementioned criteria. It also comprises nautical charts that depict latitude scales and have been referred to as "[[latitude chart]]s" by other authors to distinguish them from typical portolan charts showing the Mediterranean, which some scholars believe were created upon a large body of shipborne bearing and distance data observed through [[dead reckoning]] navigation during the Late Middle Ages.<ref name="Gaspar2013">{{cite journal |last1=Gaspar |first1=Joaquim Alves |title=From the Portolan Chart to the Latitude Chart: The silent cartographic revolution |journal=CFC |date=June 2013 |issue=216 |pages=67–77 |url=http://www.lecfc.fr/new/articles/216-article-6.pdf}}</ref>
== Specific features of portolan charts == === Rhumb lines === {{Main|Rhumbline network}} Portolan charts are characterized by their [[rhumbline network]]s, which emanate out from [[compass rose]]s located at various points on the map. The lines in these networks are generated by compass observations to show lines of constant [[bearing (navigation)|bearing]]. Though often called rhumbs, they are better called "[[windrose line]]s": As cartographic historian Leo Bagrow states, "…the word [''loxodromic'' or ''rhumb chart''] is wrongly applied to the sea-charts of this period, since a loxodrome gives an accurate course only when the chart is drawn on a suitable projection. Cartometric investigation has revealed that no projection was used in the early charts…".<ref name="Bagrow2010">{{cite book|author=Leo Bagrow|title=History of Cartography|url=https://books.google.com/books?id=OBeB4tDmJv8C&pg=PA65|year=2010|publisher=Transaction Publishers|isbn=978-1-4128-2518-4|pages=65}}</ref>
The straight lines shown criss-crossing portolan charts represent the sixteen directions (or headings) of the mariner's compass from a given point, which became thirty-two directions from around 1450.<ref>Campbell 1987, page 396</ref> The principal lines are oriented to the [[magnetic north pole]].<ref name="Discover-2014.06">Rehmeyer, Julie. [http://discovermagazine.com/2014/june/14-the-mapmakers-mystery The Mapmaker's Mystery], [[Discover (magazine)|''Discover'']], June 2014, pp. 44–49 (subscription).</ref> Thus the grid lines varied slightly for charts produced in different eras, due to the natural changes of the Earth's [[magnetic declination]].<ref name="Discover-2014.06" /> These lines are similar to the [[compass rose]] displayed on later maps and charts. "All portolan charts have wind roses, though not necessarily complete with the full thirty-two points; the compass rose ... seems to have been a Catalan innovation".<ref name=":0">Campbell 1987, page 389</ref>
=== Symbols === [[File:Eastern Azov, 1466 Portolan chart.jpg|thumb|Symbols representing navigational hazards seen on a 1466 portolan chart.]] Portolan charts use symbols to represent navigational hazards such as reefs, rocks, shoals, and sandbanks.<ref>{{Cite journal |last=Campbell |first=Tony |last2=Barritt |first2=M.K. |date=December 2020 |title=The Representation of Navigational Hazards: The Development of Toponymy and Symbology on Portolan Charts from the 13th Century onwards |url=https://www.hakluyt.com/downloadable_files/Journal/Campbell%20Barritt.pdf |journal=The Journal of the Hakluyt Society |pages=2}}</ref> In some early portolan charts, dated to the thirteenth century, black dots denoted rocks, and red dots sand or shoals.<ref name=":07">{{Cite journal |last=Campbell |first=Tony |last2=Barritt |first2=M.K. |date=December 2020 |title=The Representation of Navigational Hazards: The Development of Toponymy and Symbology on Portolan Charts from the 13th Century onwards |url=https://www.hakluyt.com/downloadable_files/Journal/Campbell%20Barritt.pdf |journal=The Journal of the Hakluyt Society |pages=7}}</ref> The symbol + is the earliest known cartographic symbol on nautical charts, representing submerged or barely visible rocks.<ref name=":6">{{Cite journal |last=Sutlović |first=Julijan |date=September 2025 |title=Signs Related to the Safety of Navigation on Late Medieval and Early Modern Nautical Charts of the Adriatic Sea, circa 1270 - 1824 |url=https://www.sciencedirect.com/science/article/abs/pii/S0305748824001348 |journal=Journal of Historical Geography |volume=89 |pages=35}}</ref> This symbol is at times combined with others to represent a group of rocks or sandbanks.<ref name=":07" /> The earliest surviving chart, the 1280 [[Carta Pisana|Carte Pisana]], features symbols for hazards entirely in black, and denotes rocks or rocks awash using only the cross/plus symbol.<ref name=":07" /><ref name=":6" /> Within surviving charts the use of two colors was first recorded in the 1313 Vesconte atlas.<ref name=":07" /> Charts did not include a key for these symbols, but occasionally they were accompanied by names or comments.<ref name=":7">{{Cite journal |last=Sutlović |first=Julijan |date=September 2025 |title=Signs Related to the Safety of Navigation on Late Medieval and Early Modern Nautical Charts of the Adriatic Sea, circa 1270 - 1824 |url=https://www.sciencedirect.com/science/article/abs/pii/S0305748824001348 |journal=Journal of Historical Geography |volume=89 |pages=36}}</ref> These names were often placed at the nearest coastal point to the hazard, but within the coastline.<ref name=":07" />
Arbitrary symbols for navigational hazards such as the plus/cross are not standardized and vary greatly from one mapmaker's work to another, and even within the works of an individual mapmaker.<ref>Clawson, Mary G. [https://api.drum.lib.umd.edu/server/api/core/bitstreams/ebdc87ca-76f5-43b1-873d-882d8e8847bf/content "The Evolution of Symbols on Nautical Charts Prior to 1800."] Master's thesis, University of Maryland, 1979. p. 24.</ref> However, despite its many variations and additions throughout time and across different charts, the + symbol represents rocks/rocks awash even in today's nautical charts.<ref name=":7" /> Symbols designed instead as abstract representations of the hazard are more consistent across different charts, and many of such symbols are also still in use in nautical charts today.<ref name=":15">Clawson, Mary G. [https://api.drum.lib.umd.edu/server/api/core/bitstreams/ebdc87ca-76f5-43b1-873d-882d8e8847bf/content "The Evolution of Symbols on Nautical Charts Prior to 1800."] Master's thesis, University of Maryland, 1979. p. 27.</ref> As well as symbols for navigational hazards, some portolan charts also feature pictorial symbols representing features such as anchorage, lighthouses, beacons, and buoys.<ref name=":15" />
== Use == The portolan chart combined the exact notations of the text of the [[periplus]] or pilot book with the decorative illustrations of a medieval [[T and O map]]. In addition, the charts provided realistic depictions of shores. Many historians believe they were meant for practical use by mariners of the period. Portolans failed to take into account the [[curvature of the Earth]]; as a result, they were not helpful as navigational tools for crossing the [[open ocean]], and were replaced by later [[Mercator projection]] charts.<ref name="Discover-2014.06" /> Portolans were most useful in close quarters identification of landmarks.<ref name="Discover-2014.06" /> They were, in a sense, "'catalogue[s] of directions to follow between notable points and mnemonics for recalling lists of ports."<ref>{{Cite journal |last=Turnbull |first=David |title=Cartography and Science in Early Modern Europe: Mapping the Construction of Knowledge Spaces |journal=Imago Mundi |volume=48 |pages=9–10 |via=JSTOR}}</ref> Portolan charts were also useful for navigation in smaller bodies of water, such as the [[Mediterranean Sea|Mediterranean]], [[Black Sea|Black]], or [[Red Sea]]s. Additionally, in some instances the charts may have been used for travel inland by waterways for trade purposes, specifically in the context of [[Hungary]], as several charts single out that country for special detail, such as showing many cities and riverways in Hungary.<ref>{{Cite journal |last=Krisztina |first=Iras |title=Hungary on Two Portolan Charts by Angelino Dulcert (1325/30, 1339) |journal=Imago Mundi |volume=59 |issue=2 |pages=223 |via=JSTOR}}</ref>
Scholars have also shown a dichotomy between portolan charts used for display purposes and ones used for navigation aboard ships, the latter of which largely do not survive to the modern day.<ref name=":13">{{Cite book |last=Nicolai |first=Roel |title=The Enigma of the Origin of Portolan Charts: A Geodetic Analysis of the Hypothesis of a Medieval Origin |date= |publisher=Brill |year=2016 |pages=46–49}}</ref> Some of these scholars have argued that many or even most portolan charts were not created for practical navigational uses, but rather as an ornamental item to "show off the owner's worldliness."'''<ref name=":42">{{Cite journal |last=Sheehan |first=Kevin E. |date=2013 |title=Aesthetic Cartography: The Cultural Function of Portolan Charts from 1300 to 1700 |url=https://www.jstor.org/stable/23481652?searchText=&searchUri=%2Faction%2FdoBasicSearch%3FQuery%3Dportolan%2Bcharts%26so%3Drel&ab_segments=0%2Fbasic_search_gsv2%2Fcontrol&searchKey=&refreqid=fastly-default%3Acd75d2e6ac1871740993f2915698fad9&initiator=recommender&seq=1 |journal=Imago Mundi |volume=65 |issue=1 |pages=133}}</ref>''' Examples of evidence that has led scholars to this theory are that some documented chart owners had no evident connection to seafaring, and that records show instances such as a merchant commissioning a chart depicting the parts of the Mediterranean he traveled after returning from his voyage, seemingly as a souvenir and not a guide.<ref name=":42" />'''<ref>{{Cite journal |last=Houssaye Michienzi |first=Ingrid |last2=Vagnon |first2=Emmanuelle |date=2019 |title=Commissioning and Use of Charts Made in Majorca c. 1400: New Evidence from a Tuscan Merchant's Archive |url=https://www.jstor.org/stable/48547963?searchText=Commissioning+and+Use+of+Charts+Made+in+Majorca+c.1400+New+Evidence+from+a+Tuscan+Merchant%27s+Archive&searchUri=%2Faction%2FdoBasicSearch%3FQuery%3DCommissioning%2Band%2BUse%2Bof%2BCharts%2BMade%2Bin%2BMajorca%2Bc.1400%253A%2BNew%2BEvidence%2Bfrom%2Ba%2BTuscan%2BMerchant%25E2%2580%2599s%2BArchive%26so%3Drel&ab_segments=0%2Fspellcheck_basic_search%2Ftest&refreqid=fastly-default%3Aebe69dfda0c1a5c7065749cda3b16110&seq=7 |journal=Imago Mundi |volume=71 |issue=1 |pages=27–28}}</ref>''' The true historical use of portolan charts remains a debate among historians of the subject, and many arguments have been made both for their use as navigational tools and as decorative objects.<ref>{{Cite journal |last=Houssaye Michienzi |first=Ingrid |last2=Vagnon |first2=Emmanuelle |date=2019 |title=Commissioning and Use of Charts Made in Majorca c. 1400: New Evidence from a Tuscan Merchant's Archive |url=https://www.jstor.org/stable/48547963?searchText=Commissioning+and+Use+of+Charts+Made+in+Majorca+c.1400+New+Evidence+from+a+Tuscan+Merchant%27s+Archive&searchUri=%2Faction%2FdoBasicSearch%3FQuery%3DCommissioning%2Band%2BUse%2Bof%2BCharts%2BMade%2Bin%2BMajorca%2Bc.1400%253A%2BNew%2BEvidence%2Bfrom%2Ba%2BTuscan%2BMerchant%25E2%2580%2599s%2BArchive%26so%3Drel&ab_segments=0%2Fspellcheck_basic_search%2Ftest&refreqid=fastly-default%3Aebe69dfda0c1a5c7065749cda3b16110&seq=1 |journal=Imago Mundi |volume=71 |issue=1 |pages=22}}</ref>
== Production == Most extant portolan charts from before 1500 are drawn on [[vellum]], which is a high-quality type of [[parchment]], made from [[Calf (animal)|calf]] skin. Single charts were normally rolled whereas those that formed part of atlases were pasted on wood or cardboard supports.<ref>Campbell 1987, page 376</ref>
The earliest surviving explanations of how to draw a portolan chart date from the 16th century,<ref>For example Martín Cortés, ''Arte de navegar'', 1551</ref> so the techniques used by medieval mapmakers can only be inferred. The instruments available in the Middle Ages are believed to have been a ruler, a pair of dividers, a pen, and inks of various colors. Drawing probably started with the windrose lines and then the mapmaker copied the coastal outlines from some earlier chart. Place names, geographic details and decoration were added in the end.<ref>Campbell 1987, pages 391-392</ref>
Portolan charts, being entirely handcrafted before 1600, were initially replicated through tracing and therefore often contained errors and inaccuracies.'''<ref name=":22">{{Cite journal |last=Sutlović |first=Julijan |date=September 2025 |title=Signs Related to the Safety of Navigation on Late Medieval and Early Modern Nautical Charts of the Adriatic Sea, circa 1270 - 1824 |url=https://www.sciencedirect.com/science/article/abs/pii/S0305748824001348 |journal=Journal of Historical Geography |volume=89 |pages=31}}</ref>''' However, over time the invention of printing technologies transformed chart production capabilities.<ref name=":22" /> The first printed chart was produced in 1472 using a [[woodcut]] technique, and [[Etching|copperplate]] printing arose shortly thereafter, in 1477.'''<ref>{{Cite journal |last=Sutlović |first=Julijan |date=September 2025 |title=Signs Related to the Safety of Navigation on Late Medieval and Early Modern Nautical Charts of the Adriatic Sea, circa 1270 - 1824 |url=https://www.sciencedirect.com/science/article/abs/pii/S0305748824001348 |journal=Journal of Historical Geography |volume=89 |pages=31–32}}</ref>''' These new printing capabilities allowed charts to be produced in much larger numbers and far more accurately, with copperplate printing especially useful in producing finer lines, smaller letters, and more detailed symbols.<ref name=":32">{{Cite journal |last=Sutlović |first=Julijan |date=September 2025 |title=Signs Related to the Safety of Navigation on Late Medieval and Early Modern Nautical Charts of the Adriatic Sea, circa 1270 - 1824 |url=https://www.sciencedirect.com/science/article/abs/pii/S0305748824001348 |journal=Journal of Historical Geography |volume=89 |pages=32}}</ref> After their invention, both printing techniques remained in simultaneous use for the next century, with copperplate printing later becoming the preferred method.<ref name=":32" />
=== Production centers === [[File: Maggiolo - Portolankarte - 1541.png |thumb|Portolan chart of 1541]] Two main families of portolan charts were distinguished by origin, according to 19th-century historians: Italian, developed mainly in [[Genoa]], [[Venice]] and [[Rome]]; and Spanish, with [[Palma de Mallorca]] as a main center of production. Portuguese charts were believed to be derived from the Spanish. Arab portolan charts were not recognized until the second half of the 20th century.
====Italian ==== The copious number of Italian portolan charts begins in the mid 13th century, with the oldest called [[Carta Pisana]], which is kept in the National Library in Paris. To the next century belong the Carignano Chart, disappeared from the National Archive of [[Florence]] where it had been conserved for a long time; cartographic works of the Genoese [[Pietro Vesconte]], the illustrator of the work of [[Marino Sanuto the Elder|Marino Sanudo]]; the chart of [[Domenico and Francesco Pizzigano|Francesco Pizigano]] (1373), with stylistic influence from Mallorca; and those of [[Beccario]], [[Albino de Canepa|Canepa]] and the brothers [[Brothers Benincasa|Benincasa]], natives of [[Ancona]]. The fifteenth-century [[Luxoro Atlas]], whose authorship is anonymous, is held at the [[Biblioteca Civica Berio]] in [[Genoa]].
====Catalan==== [[File:Gabriel Vallseca. Museo Marítimo, Barcelona.1439.jpg|thumb|1439 portolan chart by Gabriel de Vallseca (Museu Maritim, Barcelona)]] The Spanish introduced a novelty in nautical cartography, with geographical maps having common stylistic representation of certain accidents and locations. The masterpiece of the Majorcan portolan charts is the [[Atlas Catalan|Catalan Atlas]] made by [[Abraham Cresques]] in 1375, and kept in the [[Bibliothèque Nationale de France]] in [[Paris]].
[[Abraham Cresques]] was a Majorcan Jew who worked at the service of [[Pedro IV of Aragon]]. In his "buxolarum" [=[[Magnetic Compass|magnetic compass]]] workshop he was helped by his son Jafuda. The Atlas is a World Map, that is, world map and regions of the Earth with the various peoples who live there. The work was done at the request of Prince John, son of Pedro IV, desirous of a faithful representation of the world from west to east. 12 sheets form the world map on tables, linked to each other by [[scroll]] and screen layout. Each table measures 69 by 49 cm. The first four texts are filled with geographical and astronomical tables and calendars. The newest of the Cresques World Map is the representation of Asia, from the [[Caspian Sea|Caspian]] sea to [[Cathay]] (China), which takes into account information from Marco Polo, and Jordanus .
In the 14th century, also highlights the work of [[Guillem Soler]], which cultivates both styles, the purely nautical and nautical-geographical. To the 15th century corresponds the famous portolan chart by [[Gabriel Vallseca]], (1439)'','' kept in the [[Maritime Museum of Barcelona]], notable for its delicacy of execution and lively picturesque details, masked by a spot of [[ink]] left by [[Frédéric Chopin]] and [[George Sand]].<ref name="Sand1843">{{cite book|author=George Sand|title=Oeuvres complètes de George Sand|url=https://books.google.com/books?id=wv0TAAAAQAAJ&pg=PA69|year=1843|publisher=Perrotin|pages=69–}}</ref>
====Portuguese ==== [[File:Jorge Aguiar 1492 MR.jpg|right|thumb|Portolan chart by Jorge de Aguiar (1492), the oldest known signed and dated chart of Portuguese origin (Beinecke Rare Book and Manuscript Library, Yale University, New Haven, USA)]] The Portuguese portolan charts come from the Majorcan tradition,<ref>{{cite book|title=Estudos de História, Volume III|url=https://books.google.com/books?id=dVc0MZsZj48C&q=pacheco+pereira+mandou+%C3%A1+ilha+de+Malhorca+por+um+mestre+Jacome%2C+mestre+de+cartas+de+marear%2C&pg=PA10|publisher=UC Biblioteca Geral 1|pages=10–|id=GGKEY:7186FCQBHS5}}</ref> and as traditional portolan charts did not fulfill the requirements demanded by the expansion of the geographic horizons attained by Portuguese and Spaniards, they superposed the astronomical lines of the equator and tropics on top of the wind line network, and they continued being elaborated over the 16th and 17th centuries.
====Arab ==== Three medieval portolan charts written in Arabic are preserved:<ref name="Ducene">{{Cite journal|last=Ducène|first=Jean-Charles|date=2013-06-01|title=Le portulan arabe décrit par Al-'Umari|url=http://www.lecfc.fr/new/articles/216-article-7.pdf|journal=CFC|issue=216|pages=81–90}}</ref>
*Map of [[Ahmed ibn Suleiman al-Tangi]] from 1413 to 1414.<ref>Herrera Casais, Mónica. '[https://www.academia.edu/25842182/The_1413_14_sea_chart_of_A%E1%B8%A5mad_al_%E1%B9%ACanj%C4%AB The 1413-14 sea chart of Ahmad al-Ţanjī]', in: Emilia Calvo, Mercè Comes, Roser Puig & Mónica Rius (eds) ''A shared legacy: Islamic science East and West. Homage to Prof. J.M. Millàs Vallicrosa'' (Barcelona: Universitat de Barcelona, 2008) pp.283-307.</ref> *Map of [[Ibrahim al-Tabib al-Mursi]] from 1461 *Map of western Europe, anonymous and undated, preserved in the [[Ambrosiana Library]], dating from the 14th <ref name = "Vernet">{{Cite journal | volume = 16 | pages = 1–16 | last = Vernet Ginés | first = John | title = The Maghreb in the Biblioteca Ambrosiana Chart | date = 1962}}</ref> or 15th centuries.
In addition there is a detailed description of a nautical Arab map of the Mediterranean in the Encyclopedia of the Egyptian [[Ibn Fadlallah al-Umari|Ibn Fadl Allah al-'Umari]], written between 1330 and 1348.<ref name = "Ducene" /> There are also descriptions limited to smaller geographic regions, in a work of [[Ibn Sa'id al-Maghribi|Ibn Sa'id al Maghribi]] (13th century) and even in the work of [[Al-Idrisi]] (12th century).<ref name = "Vernet" />
==Theories of origin== While the production dates of portolan charts are mainly clear and undisputed, the origin of the spatial data utilised in their creation remains scientifically unresolved, as no less accurate earlier mediaeval nautical charts have been uncovered, nor have late mediaeval cartographers documented precise information on how the data underlying their creations were initially observed.<ref>Campbell 1987, page 380</ref> There have been many hypotheses about their origin, including creation by neolithic, Greek, Roman, and Egyptian civilizations,<ref name=":13"/> and still others have suggested that given the adornment and ownership records of many of the charts, they may not have even served a practical navigational role.'''<ref>{{Cite journal |last=Sheehan |first=Kevin |date=2013 |title=Aesthetic Cartography: The Cultural Function of Portolan Charts from 1300 to 1700 |journal=Imago Mundi |volume=65 |issue=1 |pages=133 |via=Jstor}}</ref>''' However, there are two principal scholarly hypotheses concerning their origin that have emerged out of the many competing ideas, which can broadly be lumped into two categories: the mediaeval origins hypothesis and the pre-medieval origins hypothesis.<ref name=":04">{{Cite journal |last=Nicolai |first=Roel |date= |title=The Premedieval Origin of Portolan Charts: New Geodetic Evidence |url=https://doi.org/10.1086/683532 |journal=Isis |volume=106 |issue=3 |pages=535–536 |doi=10.1086/683532 |issn=0021-1753|url-access=subscription }}</ref>
* '''The medieval origins hypothesis''', which mainly stems from a traditional descriptive approach, states that a large body of bearing and distance observations, systematically observed by sailboat navigators throughout the [[Mediterranean Sea|Mediterranean]], [[Black Sea]], and East Atlantic during their dead reckoning navigations in the late medieval period, was compiled and presented to cartographers, who then transformed it into a coherent graphical representation known as a portolan chart.<ref>{{Cite book |last=Pujades i Bataller |first=Ramon J. |title=Les cartes portolanes: la representació medieval d'una mar solcada |date=2007 |publisher=Inst. Cartogràfic de Catalunya |others=Institut Cartogràfic de Catalunya |isbn=978-84-9785-414-6 |edition=1. |location=Barcelona}}</ref><ref name=":5" /><ref>{{Cite journal |last=Gaspar |first=Joaquim Alves |date=2025-01-02 |title=The origin of nautical cartography: certitudes, doubts, and perplexities |url=https://doi.org/10.1080/23729333.2023.2240902 |journal=International Journal of Cartography |volume=11 |issue=1 |pages=63–92 |doi=10.1080/23729333.2023.2240902 |bibcode=2025IJCar..11...63G |issn=2372-9333|url-access=subscription }}</ref><ref>{{Cite book |last=Puchades i Bataller |first=Ramon Josep |title=Els Mapamundis baixmedievals: del naixement del mapamundi híbrid a l'ocàs del mapamundi portolà |date=2023 |publisher=Generalitat de Catalunya ICGC, Institut Cartogràfic i Geològic de Catalunya |isbn=978-84-19695-27-7 |edition=Primera edició |location=Barcelona}}</ref> * '''The pre-medieval origins hypothesis''', mainly built on the synthesis of cartometric analyses and known historical records, posits that portolan charts exhibit an accuracy that surpasses what could be expected from genuine mediaeval artefacts, indicating they are likely late medieval reproductions of some earlier-made maps or charts.<ref name=":2" /><ref name=":3" /><ref name=":4" /><ref>{{Cite book |last=Nicolai |first=Roel |title=The enigma of the origin of Portolan charts: a geodetic analysis of the hypothesis of a medieval origin |date=2016 |publisher=Brill |isbn=978-90-04-28297-1 |series=History of science and medicine library |location=Leiden; Boston}}</ref><ref>{{Cite journal |last=Nicolai |first=Roel |title=The origin problem of nautical cartography: the importance of evidence and method |url=https://doi.org/10.1080/23729333.2024.2352822 |journal=International Journal of Cartography |date=2024 |volume=0 |pages=1–25 |doi=10.1080/23729333.2024.2352822 |issn=2372-9333|url-access=subscription }}</ref>
One study<ref name="Nicolai2014">Nicolai, R. (2014) [http://www.dart-europe.eu/full.php?id=1139867 A critical review of the hypothesis of a medieval origin for portolan charts] {{Webarchive|url=https://web.archive.org/web/20220614211123/https://www.dart-europe.eu/full.php?id=1139867 |date=2022-06-14 }}. Uitgeverij Educatieve Media</ref> concludes that portolans originated from earlier charts drawn on what is now called the [[Mercator projection]], stating that portolans are mosaics of smaller charts, each with their own scale and orientation, and suggesting that the cartographic capabilities of whichever civilization produced the antecedent charts were more advanced than is currently acknowledged.<ref>{{cite web |last1=Jacobs |first1=Frank |title=Portolan Charts 'Too Accurate' to be Medieval |url=https://bigthink.com/strange-maps/648-portolan-charts-too-accurate-to-be-medieval |website=Big Think |date=10 March 2014 |access-date=30 August 2018}}</ref> This publication led certain researchers in the field to react to those ideas,<ref name="Gaspar"> {{cite journal |last=Gaspar |first = Joaquim Alves |title = Review of Roel Nicolai's article by Joaquim Alves Gaspar |year = 2015 |journal = Maps in History |volume = 53 |url = https://www.bimcc.org/newsletters/53 }}</ref><ref name="Campbell"> {{cite journal |last=Campbell |first = Tony |title = Review of Roel Nicolai's article by Tony Campbell |year = 2015 |journal = Maps in History |volume = 53 |url = https://www.bimcc.org/newsletters/53 }}</ref> but the criticism was not based on sufficiently strong arguments.<ref>{{Cite web |last=Nicolai |first=Roel |title=How Old are Portolan Charts Really? |url=https://www.bimcc.org/newsletters/54 |series=Maps in History 54 |publisher=The Brussels Map Circle |publication-date=September 2015}}</ref> To counter the hypothesis of the Mercator projection, some scholars have suggested that the Portolan charts were constructed using plane charting.<ref name=":04"/> However, the plane charting method would introduce inaccuracies into the charts, since this method does not take into account the curvature of the Earth.<ref name=":04"/> Along with the apparently strong correlation between the Mercator projection and the Portolan charts, these inaccuracies from plane charting have led some scholars to advocate for the Portolan charts being the summation of many smaller charts, likely using some form of the Mercator Projection.<ref name=":04"/>
It has been proposed that portolan charts evolved from the mental maps that Mediterranean [[Pilot (shipping)|pilots]] had used since ancient times, which had been [[oral tradition|transmitted orally]] over generations.<ref name=":5">{{cite web |last1=Campbell |first1=Tony |title=Mediterranean portolan charts: their origin in the mental maps of medieval sailors, their function and their early development |url=https://www.maphistory.info/PortolanOriginsMENU.html |access-date=6 October 2021 |language=en |date=2021}}</ref> Additionally, the one method used to make the earliest portolan charts was by "'averaging'" the data taken by many sailors over many years in order to increase the level of accuracy without using map projections.<ref>{{Cite journal |last=Nicolai |first=Roel |date=September 2015 |title=The Premedieval Origin of Portolan Charts: New Geodetic Evidence |journal=Isis |volume=106 |issue=3 |pages=522–523}}</ref>
== Evolution == The earliest portolan charts focused on the [[Mediterranean Sea|Mediterranean]] and [[Black Sea]] coasts, with only partial and sometimes sketchy depiction of Atlantic coasts up to Scandinavia. In the 15th and 16th centuries, with the beginning of the [[Age of Discovery]], the scope of portolan charts expanded south down to the [[Gulf of Guinea]]. Charts also started to be drawn by Portuguese and Spanish mapmakers for the newly explored seas in [[Africa]], [[Americas|America]], South Asia and the Pacific. Further, [[Portuguese Empire|Portuguese]] [[Cartography|cartographers]] used astronomical data to add [[latitude]] lines to the charts.<ref name=":13"/> As time progressed, the charts transitioned from being drawn on [[vellum]] to being drawn on paper.<ref name=":13" />
== See also == * [[Antillia]] * [[Catalan chart]] * [[Classical compass winds]] * [[Cornaro Atlas]] * [[La Cartografía Mallorquina]] * [[Majorcan cartographic school]] * [[Rule of Marteloio]] * [[Thames school of chartmakers]]
==References== {{refbegin}} {{Reflist|2|refs= }}
==Further reading== #Konrad Kretschmer, ''Die italienischen Portolane des Mittelalters, Ein Beitrag zur Geschichte der Kartographie und Nautik,'' Berlin, Veröffentlichungen des Instituts für Meereskunde und des geographischen Instituts an der Universität Berlin, Vol. 13, 1909. [https://iiif.lib.harvard.edu/manifests/view/drs:46828924$5i (available online)] #Alessandra D. Debanne, ''Lo Compasso de navegare. Edizione del codice Hamilton 396 con commento linguistico e glossario'', Brussels, Peter Lang for the Gruppo degli italianisti delle Università francofone del Belgio, 2011. #Patrick Gautier Dalché, ''Carte marine et portulan au XIIe siècle. Le Liber de existencia rivieriarum et forma maris nostri Mediterranei, Pise, circa 1200'', Roma, École Française de Rome, 1995. [http://www.persee.fr/doc/efr_0223-5099_1995_mon_203_1 (available online)] #Tony Campbell, "Portolan Charts from the Late Thirteenth Century to 1500", Chapter 19 of ''The History of Cartography'', Volume I. U. of Chicago Press, 74th edition (May 15, 1987). [http://www.press.uchicago.edu/books/HOC/HOC_V1/HOC_VOLUME1_chapter19.pdf (available online)] {{refend}}
==External links== {{Commons category|Portolan charts}} * [http://www.maphistory.info/portolan.html A Critical Re-examination of Portolan Charts, with a Reassessment of Their Replication and Seaboard Function], ongoing collection of essays and tabulated data by Tony Campbell, comprising about 30 separate web publications, over 120 tables and graphs, a census of surviving charts pre-1500 and a comprehensive bibliography. * [http://www.elgranerocomun.net/IMG/pdf/Cartografia_Mallorquina_JRP_EGC.pdf J. Rey Pastor & E. Garcia Camarero ''La cartografía mallorquina''] {{in lang|es}} * Images of portolan charts: ** [https://medea.fc.ul.pt/main MEDEA-CHART], University of Lisbon, Portugal ** [http://www.lib.umn.edu/apps/bell/map/PORTO/porto.html Portolan Charts] mini-site, [[University of Minnesota]] ** [http://beinecke.library.yale.edu/digitallibrary/portolan.html Portolan Charts], samples from [[Yale University]]
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{{DEFAULTSORT:Portolan Chart}} [[Category:Nautical charts]] [[Category:Manuscripts]] [[Category:Navigational equipment]]