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Portolan charts are
nautical chart A nautical chart is a graphic representation of a sea area and adjacent coastal regions. Depending on the scale of the chart, it may show depths of water and heights of land ( topographic map), natural features of the seabed, details of the co ...
s, first made in the 13th century in the
Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on ...
basin and later expanded to include other regions. The word ''portolan'' comes from the Italian ''portulano'', meaning "related to
port A port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as H ...
s or
harbors A harbor (American English), harbour (British English; see spelling differences), or haven is a sheltered body of water where ships, boats, and barges can be docked. The term ''harbor'' is often used interchangeably with ''port'', which is a ...
", and which since at least the 17th century designates "a collection of sailing directions".


Definition

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. Other names that have been proposed include
rhumb line In navigation, a rhumb line, rhumb (), or loxodrome is an arc crossing all meridians of longitude at the same angle, that is, a path with constant bearing as measured relative to true north. Introduction The effect of following a rhumb l ...
charts, compass charts or loxodromic charts whereas modern French scholars prefer to call them nautical charts to avoid any relationship with portolani. Several definitions of portolan chart coexist in the literature. A narrow definition includes only medieval or, at the latest, early modern sea charts (i.e. maps that primarily cover maritime rather than inland regions) that include a network of rhumb lines and do not show any indication of the use of
latitude In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north ...
or
longitude Longitude (, ) is a geographic coordinate that specifies the east– west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek let ...
coordinates. The geographic scope 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, whereas books that contain several sea charts are called nautical
atlas An atlas is a collection of maps; it is typically a bundle of maps of Earth or of a region of Earth. Atlases have traditionally been bound into book form, but today many atlases are in multimedia formats. In addition to presenting geogra ...
es. A broader definition of portolan chart accepts any sea chart or atlas that meets the following series of stylistic requirements: drawn by hand, with a network of rhumb lines that emanate from the center of hidden circles, focused on the coasts and islands, with place names written perpendicular to the coastline on the land side and with sparse information about the interior of landmasses. This broader definition encompasses charts of potentially any sea and even maps of the entire world, which are sometimes called
nautical planisphere Seamanship is the art, knowledge and competence of operating a ship, boat or other craft on water. The'' Oxford Dictionary'' states that seamanship is "The skill, techniques, or practice of handling a ship or boat at sea." It involves topics a ...
s, provided they meet the aforesaid criteria. It also includes nautical charts that depict latitude scales and have been called “
latitude chart In geography, latitude is a coordinate that specifies the north–south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north pole ...
s” by other authors to distinguish them from proper portolan charts, which are believed to have been constructed on the basis of
dead reckoning In navigation, dead reckoning is the process of calculating current position of some moving object by using a previously determined position, or fix, and then incorporating estimates of speed, heading direction, and course over elapsed time. ...
information.


Contents


Rhumb lines

Portolan charts are characterized by their
rhumbline network A rhumbline network, more properly called, a windrose network, or sometimes also called harbour-finding chart, compass chart, or rhumb chart, is a navigational aid drawn on early portolan charts dating from the medieval to early modern peri ...
s, which emanate out from
compass rose A compass rose, sometimes called a wind rose, rose of the winds or compass star, is a figure on a compass, map, nautical chart, or monument used to display the orientation of the cardinal directions (north, east, south, and west) and thei ...
s located at various points on the map. The lines in these networks are generated by compass observations to show lines of constant bearing. Though often called rhumbs, they are better called " windrose lines": 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…". 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. The principal lines are oriented to the magnetic north pole.Rehmeyer, Julie
The Mapmaker's Mystery
''Discover'', June 2014, pp. 44–49 (subscription).
Thus the grid lines varied slightly for charts produced in different eras, due to the natural changes of the Earth's
magnetic declination Magnetic declination, or magnetic variation, is the angle on the horizontal plane between magnetic north (the direction the north end of a magnetized compass needle points, corresponding to the direction of the Earth's magnetic field lines) an ...
. These lines are similar to the
compass rose A compass rose, sometimes called a wind rose, rose of the winds or compass star, is a figure on a compass, map, nautical chart, or monument used to display the orientation of the cardinal directions (north, east, south, and west) and thei ...
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".


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 A T and O map or O–T or T–O map (''orbis terrarum'', orb or circle of the lands; with the letter T inside an O), also known as an Isidoran map, is a type of early world map that represents the physical world as first described by the 7th-ce ...
. In addition, the charts provided realistic depictions of shores. 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, being replaced by later
Mercator projection The Mercator projection () is a cylindrical map projection presented by Flemish geographer and cartographer Gerardus Mercator in 1569. It became the standard map projection for navigation because it is unique in representing north as up and s ...
charts. Portolans were most useful in close quarters' identification of landmarks. ''Portolani'' were also useful for navigation in smaller bodies of water, such as the
Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on ...
,
Black Black is a color which results from the absence or complete absorption of visible light. It is an achromatic color, without hue, like white and grey. It is often used symbolically or figuratively to represent darkness. Black and white ha ...
, or
Red Sea The Red Sea ( ar, البحر الأحمر - بحر القلزم, translit=Modern: al-Baḥr al-ʾAḥmar, Medieval: Baḥr al-Qulzum; or ; Coptic: ⲫⲓⲟⲙ ⲛ̀ϩⲁϩ ''Phiom Enhah'' or ⲫⲓⲟⲙ ⲛ̀ϣⲁⲣⲓ ''Phiom ǹšari''; ...
s.


Production

Most extant portolan charts from before 1500 are drawn on
vellum Vellum is prepared animal skin or membrane, typically used as writing material. Parchment is another term for this material, from which vellum is sometimes distinguished, when it is made from calfskin, as opposed to that made from other anim ...
, which is a high-quality type of
parchment Parchment is a writing material made from specially prepared untanned skins of animals—primarily sheep, calves, and goats. It has been used as a writing medium for over two millennia. Vellum is a finer quality parchment made from the skins ...
, made from
calf Calf most often refers to: * Calf (animal), the young of domestic cattle. * Calf (leg), in humans (and other primates), the back portion of the lower leg Calf or calves may also refer to: Biology and animal byproducts *Veal, meat from calves *C ...
skin. Single charts were normally rolled whereas those that formed part of atlases were pasted on wood or cardboard supports. The earliest surviving explanations of how to draw a portolan chart date from the 16th century, 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.


Production centers

Two main families of portolan charts were distinguished by origin, according to 19th-century historians: Italian, developed mainly in
Genoa Genoa ( ; it, Genova ; lij, Zêna ). is the capital of the Italian region of Liguria and the sixth-largest city in Italy. In 2015, 594,733 people lived within the city's administrative limits. As of the 2011 Italian census, the Province of ...
,
Venice Venice ( ; it, Venezia ; vec, Venesia or ) is a city in northeastern Italy and the capital of the Veneto Regions of Italy, region. It is built on a group of 118 small islands that are separated by canals and linked by over 400  ...
and
Rome , established_title = Founded , established_date = 753 BC , founder = King Romulus ( legendary) , image_map = Map of comune of Rome (metropolitan city of Capital Rome, region Lazio, Italy).svg , map_caption ...
; and Spanish, with
Palma de Mallorca Palma (; ; also known as ''Palma de Mallorca'', officially between 1983–88, 2006–08, and 2012–16) is the capital and largest city of the autonomous community of the Balearic Islands in Spain. It is situated on the south coast of 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 The ''Carta Pisana'' or ''Carte Pisane'' is a map probably made at the end of the 13th century, about 1275–1300, currently conserved in the Département des cartes et plans at the Bibliothèque nationale de France. New research suggests that it ...
, which is kept in the National Library in Paris. To the next century belong the Carignano Chart, disappeared from the National Archive of
Florence Florence ( ; it, Firenze ) is a city in Central Italy and the capital city of the Tuscany region. It is the most populated city in Tuscany, with 383,083 inhabitants in 2016, and over 1,520,000 in its metropolitan area.Bilancio demografico ...
where it had been conserved for a long time; cartographic works of the Genoese Pietro Vesconte, the illustrator of the work of Marino Sanudo; the chart of Francisco Pizigano (1373), with stylistic influence from Mallorca; and those of Beccario, Canepa and the brothers Benincasa, natives of
Ancona Ancona (, also , ) is a city and a seaport in the Marche region in central Italy, with a population of around 101,997 . Ancona is the capital of the province of Ancona and of the region. The city is located northeast of Rome, on the Adriatic ...
. The fifteenth-century Luxoro Atlas, whose authorship is anonymous, is held at the
Biblioteca Civica Berio The Biblioteca Civica Berio (est. 1775) of Genoa, Italy, is a public library founded by . Around 1998 it moved into the former in the quartiere. Among its collections is the library of Demetrio Canevari. References ''This article incorporate ...
in
Genoa Genoa ( ; it, Genova ; lij, Zêna ). is the capital of the Italian region of Liguria and the sixth-largest city in Italy. In 2015, 594,733 people lived within the city's administrative limits. As of the 2011 Italian census, the Province of ...
.


Catalan

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
Catalan Atlas The Catalan Atlas ( ca, Atles català, ) is a medieval world map, or mappamundi, created in 1375 that has been described as the most important map of the Middle Ages in the Catalan language, and as "the zenith of medieval map-work". It was p ...
made by
Abraham Cresques Abraham Cresques (, 1325–1387), whose real name was Cresques (son of) Abraham, was a 14th-century Jewish cartographer from Palma, Majorca (then part of the Crown of Aragon). In collaboration with his son, Jehuda Cresques, Cresques is credit ...
in 1375, and kept in the
Bibliothèque Nationale de France The Bibliothèque nationale de France (, 'National Library of France'; BnF) is the national library of France, located in Paris on two main sites known respectively as ''Richelieu'' and ''François-Mitterrand''. It is the national repository ...
in
Paris Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. Si ...
.
Abraham Cresques Abraham Cresques (, 1325–1387), whose real name was Cresques (son of) Abraham, was a 14th-century Jewish cartographer from Palma, Majorca (then part of the Crown of Aragon). In collaboration with his son, Jehuda Cresques, Cresques is credit ...
was a Majorcan Jew who worked at the service of Pedro IV of Aragon. In his "buxolarum" magnetic_compass.html" ;"title="Magnetic_Compass.html" ;"title="Magnetic Compass">magnetic compass">Magnetic_Compass.html" ;"title="Magnetic Compass">magnetic compassworkshop 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 to
Cathay Cathay (; ) is a historical name for China that was used in Europe. During the early modern period, the term ''Cathay'' initially evolved as a term referring to what is now Northern China, completely separate and distinct from China, which ...
(China), which takes into account information from Marco Polo, and Jordanus . In the 14th century, also highlights the work of
Guillem Soler Guillem Soler (floruit, fl. 1380s), sometimes given as Guillelmus Soleri, Guillermo Soler and Guglielmo Soleri, was a Majorcan cartographer of the 14th century. Little is known of Guillem Soler. Documents establish his existence in Majorca in 1368 ...
, which cultivates both styles, the purely nautical and nautical-geographical. To the 15th century corresponds the famous portolan chart by
Gabriel Vallseca Gabriel de Vallseca, also referred to as Gabriel de Valseca and Gabriel de Valsequa ( Barcelona, before 1408 - Palma, after 1467) was a cartographer of Jewish descent connected to the Majorcan cartographic school. His most notable map is the porto ...
, (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 Frédéric François Chopin (born Fryderyk Franciszek Chopin; 1 March 181017 October 1849) was a Polish composer and virtuoso pianist of the Romantic period, who wrote primarily for solo piano. He has maintained worldwide renown as a leadin ...
and
George Sand Amantine Lucile Aurore Dupin de Francueil (; 1 July 1804 – 8 June 1876), best known by her pen name George Sand (), was a French novelist, memoirist and journalist. One of the most popular writers in Europe in her lifetime, bein ...
.


Portuguese

The Portuguese portolan charts come from the Majorcan tradition, 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: *Map of
Ahmed ibn Suleiman al-Tangi Ahmad ( ar, أحمد, ʾAḥmad) is an Arabic male given name common in most parts of the Muslim world. Other spellings of the name include Ahmed and Ahmet. Etymology The word derives from the root (ḥ-m-d), from the Arabic (), from the ve ...
from 1413 to 1414. *Map of Ibrahim al-Tabib al-Mursi from 1461 *Map of western Europe, anonymous and undated, preserved in the
Ambrosiana Library The Biblioteca Ambrosiana is a historic library in Milan, Italy, also housing the Pinacoteca Ambrosiana, the Ambrosian art gallery. Named after Ambrose, the patron saint of Milan, it was founded in 1609 by Cardinal Federico Borromeo, whose agent ...
, dating from the 14th 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 Fadl Allah al-'Umari, written between 1330 and 1348. There are also descriptions limited to smaller geographic regions, in a work of Ibn Sa'id al Maghribi (13th century) and even in the work of Al-Idrisi (12th century).


Theories of origin

The origins of portolan charts are obscure, having no known predecessors. One studyNicolai, R. (2014
A critical review of the hypothesis of a medieval origin for portolan charts
Uitgeverij Educatieve Media
concludes that portolans originated from earlier charts drawn on what is now called the
Mercator projection The Mercator projection () is a cylindrical map projection presented by Flemish geographer and cartographer Gerardus Mercator in 1569. It became the standard map projection for navigation because it is unique in representing north as up and s ...
, states that portolans are mosaics of smaller charts, each with their own scale and orientation, and suggests that the cartographic capabilities of whichever civilization produced the antecedent charts was more advanced than is currently acknowledged. These ideas are rejected by established researchers in the field, however, who find ample evidence of medieval origins and construction methods. It has been proposed that portolan charts evolved from the mental maps that Mediterranean pilots had used since ancient times, and which were transmitted orally over generations.


Evolution

The earliest portolan charts focused on the
Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on ...
and
Black Sea The Black Sea is a marginal mediterranean sea of the Atlantic Ocean lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia, Rom ...
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 Age of Discovery (or the Age of Exploration), also known as the early modern period, was a period largely overlapping with the Age of Sail, approximately from the 15th century to the 17th century in European history, during which seafa ...
, the scope of portolan charts expanded south down to the
Gulf of Guinea The Gulf of Guinea is the northeasternmost part of the tropical Atlantic Ocean from Cape Lopez in Gabon, north and west to Cape Palmas in Liberia. The intersection of the Equator and Prime Meridian (zero degrees latitude and longitude) is i ...
. Charts also started to be drawn by Portuguese and Spanish mapmakers for the newly explored seas in
Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
,
America The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...
, South Asia and the Pacific.


See also

* Antillia * Catalan chart * Classical compass winds * Cornaro Atlas *
La Cartografía Mallorquina ''La Cartografía Mallorquina'' ('' Majorcan Cartography '') is a book of essays on the Majorcan portolans written by Professor Julio Rey Pastor with the collaboration of Ernesto García Camarero. It is a scholarly essay, a key element in the stud ...
* Majorcan cartographic school * Rule of Marteloio * Thames school of chartmakers


References


Further reading

#Konrad Kretschmer, ''Die italianischen Portolane des Mittelalters, Ein Beitrage zur Geschichte der Kartographie und Nautik,'' Berlin, Veroffentlichungen des Institut fur Meereskunde und des Geographischen Instituts an der Universitat Berlin, Vol. 13, 1909
(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
(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)
(available online)


External links



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.
J. Rey Pastor & E. Garcia Camarero ''La cartografía mallorquina''
* Images of portolan charts: *

mini-site,
University of Minnesota The University of Minnesota, formally the University of Minnesota, Twin Cities, (UMN Twin Cities, the U of M, or Minnesota) is a public land-grant research university in the Twin Cities of Minneapolis and Saint Paul, Minnesota, United States. ...
*
Portolan Charts
samples from
Yale University Yale University is a private research university in New Haven, Connecticut. Established in 1701 as the Collegiate School, it is the third-oldest institution of higher education in the United States and among the most prestigious in the w ...
{{DEFAULTSORT:Portolan Chart Map types Manuscripts Navigational equipment