View Diagrams  Download Paper  Download Images 



The Francesco Beccari chart, 1403, as Diagram ChFb/1/D01 illustrates, is held by the Beinecke Library, Yale University, as manuscript 1980.158. It is not on general display and available on request, but the library has a data sheet with digital copy available. The chart is considered one of the largest drawn, being 93 x 139.5cms., and is formed of two vellum sheets. As a Portolan chart it has not been afforded the attention of others with a technical dissection of its structure, even though those who have included it in their oeuvre have commented on its supposed uniqueness with a latitudinal scale and explanatory text appended there-on.

But, is it so unique; have researchers been influenced by the perhaps self-serving text appended and ignored the data hidden in plain sight that the chart portrays.

This text is a technical appraisal as opposed to an historical deliberation on the motifs etc., normally discussed, but, it is worth mentioning the Towns which have been highlighted there-on, in vignettes. But more importantly there are two slightly suppressed in drawing terms, but very important scale bars with differing measures over a total of 4 degrees latitude. There is no explanation of their intended usage, but they have a country of origin tag.



The most important is obviously Genoa, shown with harbour and grandiose buildings. To the west of Genoa is Avignon, (probably echoing the transference of the Papal seat), and to its north is Cologne, a Hanseatic League port as ChFb/1/D02 illustrates. To the east of Genoa is a subdued Venice, with Varna on the Black Sea far to its east. In the Levante are Damascus and Jerusalem, However there is a clear oddity on the chart; just south of the Nile Delta is placed Babilonia (it exists at 300 00’N, 310 14’E, but is obviously a transposition of cities) on the Flumen Chartxy (Tigris?). The Nile is omitted, and Alexandria is simply noted even though it is a major seaport of this age.

In the west of North Africa, Tirimessen is noted. This has been variously identified as Fez or the oasis of Sigismili, as it is not actually located in a geographical context.

In Iberia, the Church of Sancto Jacobus in Gallicia, (St Iago de Compostella) has been located with an excellent vignette. The City of Paris is indicated by its flag, and several islands have a flag drawn within their bounds.
Thus we may assume from its drawn content the chart is based upon Genoa and has no major decoration to subtract from the toponyms being clearly read.


In 2013 the following text was included in a paper entitled, “How did medieval cartographers work”, by Philipp Billion.  I quote directly there from;

“For another series of world charts we have documentary proof and no cartographic evidence. A contract between the Florentine diamond and ivory trader Baldassare degli Ubriachi from 1399 and 1400 provides details about the work of contemporary cartographers. Baldassare orders several large scale world charts from Francesco Beccari of Genova and Jafuda, the son of Abraham Cresques (see Skelton, 1968). First, a smaller prototype with only 242 signs was to be produced, while the final versions were to have 770 signs each. The text contains a detailed list of signs in different classes, such as people, animals, ships, trees and flags that had to be illuminated by Beccari. The production process is well defined here. Jafuda was supposed to draw the underlying hydrographical chart and further graphical elements that are not described in details in the document. Then an envoy was to collect those charts and take them to Francesco Beccari for illustration.

What can we learn about the production process of medieval Portolan charts? First, we can prove that the client had considerable influence on the visual language of the charts. He decided about those details of the graphic design that were fixed in the contract. By contrast, the hydrography is not described there at all. Secondly, a prototype chart is produced. The creation of a small prototype did not exist at the time of the order. Finally, the material used had to be paid separately depending on the value of ink, the parchment, etc.

This text has often been interpreted as proof of collaboration between a cartographer filling in the coastline and an illustrator drawing all the more sophisticated signs. This interpretation is wrong, as an exact analysis of the text shows. A new interpretation of distinct passages shows the work was divided between one cartographer who drew the coastlines and provided the texts, scales, rhumb-line-system, visualisation of the winds, mountains, lakes, oceans and architectural signs, while another person drew the flags and pictorial elements.”

Further in the text Billion comments as follows;

“The latest of the three schools, that of Genoa, is closely connected to the Beccari family. This school started as late as the early 15th century and ended around 1437. We can attribute five charts with the distinctive characteristic of an open rhumb-line-system with exactly six tertiary centres in constant configuration. Its characteristic feature is the depiction of only a small canon of cities as detailed and realistic architectural compositions in a perspective view. Heraldic signs are treated as accessories for architecture.
How were charts made in this school? If we compare the few charts we have, all indicators lead us towards a dynamical development with every chart. No prototypes were used, and each chart was a more or less copy of the predecessor.”

Thus armed with such compelling data we can now investigate other papers regarding the Beccari charts and then analyse minutely the construction methods utilised.


In 2012 ‘e-Perimetron’ published a text, “The Autumn of Medieval Portolan Charts, Cartometric issues”, in which the Francesco Beccari chart of 1403 was analysed. Within the text the first analysis concerned the scale of distances (P18), the fact that

many of the charts both precedent and subsequent to that of Beccari illustrate in the Atlantic profiles a certain adhesion to modern latitude data” and “more frequently, on the western borders there is a scale of distances that can be repeated on the same and on the northern and southern borders, where it may be juxtaposed to or inserted into the polychrome border. With rare exceptions, the scale of distances is framed by several parallel lines deriving from the main wind rose and from the secondary centres.”


The text under discussion, page 23 includes as figure 6, ChFb/1/D03 “Phases in the construction of Francesco Beccari’s chart of 1403”, and states, “Turning now to an analysis of the procedures employed in the making of the chart, it appears probable that the scale of latitude was drawn after Beccari had identified the western (Tenerife, L’insula de l’inferno) and eastern (Batuni?, Vati in the Black Sea surprisingly close to reality) limits of his representation, calculating the distance as if these were arranged on the same axis (fig 6, phase 1). Having identified the midpoint of this distance, he draws a vertical line: the first axis of the main wind rose (2). At this point the scale of latitude comes into play (3) which serves Beccari for identifying the centre of the main wind rose on the first vertical position. He takes as reference the latitudes of the Atlantic extremities of Rochbruch (Edinburgh, c560 27’ lat) positioned at 57 1/3rd (see table) and of the channel between Lanzarote and Feuteventura, 28 2/3rds (c280 48’ lat.). Once again, he divides this distance in two and positions the centre of the rose at a latitude of 42 ¼: this coordinate intercepts the toponym Noia in red. The next step is the construction of a circumference (4) the radius of which is calculated on the distance from the centre of the extreme points indicated above. This means that the northernmost part of England as far as Cap Wrath, that can be estimated as 58 1/3 and, to the south, the lowest point of the African coast, with Cape Bojador hidden by the laceration at the lower edge of the sheet on the 26 degree, are excluded from the circumference, being relegated to a secondary partition. After this the circumference is divided into 16 parts (5).

Starting from the northern and southern extremities of the circumference and from the sixteenths aligned on the two hemispheres, he draws six lines (6) that cross the scale of latitude: this forms a partition of as many parallel lines with distances that decrease identically on either side of the central pseudo meridian corresponding to around 5 20, 4 40 and 4 degrees (leaving the northern and southern borders to the aforementioned secondary partitions.)

At this point I must state my objection to the above text as it is negated by my research into the Wind Rose Construction and as will be indicated by the following text and diagrams, the main determinants of the chart have been missed.

But before explaining my research it is pertinent to note the comments by R J Pujades i Bataller in his 2007 monograph “Apriorismes nacionalistes i recerca historica”, as follows;

Nationalistic preconceptions and historic research Portolan Charts (Introduction.)
This article reflects on the problems arising from applying political boundaries in which the contemporary world is structured to historical analysis, focusing particularly, as an illustrative example, on the really negative consequences that it has had on the historiography of Portolan charts.”

Pujades continues,” Later, in the years of transition to the 15th C, the old Genoese patterns were dramatically upgraded by Francesco Beccari. Cartographically homogenizing scale representation of the Atlantic area and the correct location of some Mediterranean islands;
Subtitle; Limits of time and space variables.
The progress of nationalistic research, prejudices aside, in an effort to achieve a more global view of the phenomenon, has shown that the medieval cartographers in the same way had already proclaimed it without prevention. When Opicina di Canistris announced his “Mappa maris navigabilis secundum Januenses et Maioricenses; and Francesco Beccari mentioned the authority of teachers, “Catalani, Veneti, Januenses quam alii qui cartas navigandi fecerunt temporibus retroactis”, they were openly acknowledging the Mediterranean and supranational character of the mapping technique. Because they did not need to make national myths justifying political constructions and had not had problems recognising that obviously was evident.”

As the text within “e-Perimetron” has used the Pietro Vesconte 1311 chart scale base as an example it is pertinent to restate my research concerning the wind rose, scale bars and their interlocked existence. The 1321 chart exhibits precisely the same layout and detail as my original text illustrates to the 1311 chart and will thus be used later in the text to refute the comments.

MS 175 fol 1v-2r; Bibliotheque municipal de Lyon


Firstly, there is no pin hole for a compass point and no circle has been scribed as there was no necessity to do so. Secondly, the scale in the top left corner (that is when the chart is oriented north at the top) provides the most important information appertaining to the construction of the wind rose. Why is a scale required for a wind rose? It is set in a square quite precisely with the NSEW points located there-on. Thus the overall dimension is assured. Thirdly, after drawing the two major lines forming the cross, simple measurements using the scale bar can now be made and the underlying graticule of the wind rose drawn.

The measurements are a set of ratios formed by the 22.5 degree winds and are 35/30/20/7 and can be sized to suit any vellum sheet. Thus the 16 winds are located, although Petrus Vesconte only initials the main four, NSEW and the mid quadrant winds, thus 8 in total.



By using just a straight edge, the scale bar, stylus and ink the whole wind rose can be drawn quickly and efficiently. The scale bar is situate in the northwest quadrant, has five sections, the fifth being subdivided again by five. The scale bar is also used to denote the WNW wind position through its drawn width and as can be readily observed the actual five part scale is set within two longer lines; the inner terminates at the second horizontal line. My reconstruction is in the six sections below, on diagrams ChFb/1/D05 and ChFb/1/D06;

1) The external square is drawn first and the NSEW cruciform added. The square has a size which if checked against the inner alignment measures 184 units, i.e. 92 + 92 per quadrant determined by the trignometrical ratio of the 22 ½ degree segments.

2) Quadrants are then marked off from the centre point in measured ratio, 35/30/27, total 92, although in fact it would be 35/30/20/7 if all lines were required to be drawn. The outer division line which would denote the 67 ½ degree wind is omitted, the scale bar indicates it.

3) First the inner square is drawn joining the cardinal points and the 45 degree lines are drawn, but as can be seen avoid the scale bar.

4) By measurement, for the7 ratio, the eight markers for the 22 ½ degree winds are denoted by a dot.

5) The squares formed by those marked 22 ½ degree points are then drawn. At this point in the exercise there are four major squares including the outer frame.

6) All points and major lines can now be drawn denoted by their colour code, red, green and black.

Thus we can immediately observe that the research of the text being reviewed from
e-Perimetron is flawed, which has manifold repercussions for the actual research into the Francesco Beccari 1403 Portolan chart within that text.

Thus a constructional analysis of the Francesco Beccari Chart, 1403 Portolan is required.

FRANCESCO BECCARI, 1403 Portolan Chart, LCP C25, pp190-191


Firstly, although it has only a single Wind Rose which appears to be set centrally on the vellum, it is obvious the western edge has been cut (and possibly the eastern edge) to allow that observation. The Wind Rose is quite basic in its setting out, corresponding to the norms of previous Portolan charts, but being a single Wind Rose format it had to be extended east and west. Here the chart deviates from normal extension geometry of continuing the basic graticule. F Beccari by endeavouring to insert an 11.25 degree line across the whole north/south dimension has inserted a minor error in this setting out which is discussed later. The basic N/S measurement is 2 x 92 trignometrical ratio units, the standard 184tru’s, with the main scale bars set horizontally along the northern and southern limits. The northern scale bars are disjointed to the west and from the centre eastwards, but, the southern scale bar is nearly symmetrical about the wind rose centre line having 20 x 5 divisions west; 20 x 5 divisions to the east and after the Scirocco Wind roundel a further 5 x 5 divisions.
This southern scale bar is primarily enclosed by the wind rose limits but the eastern extension takes it one division further east.

Secondly, near the western edge of the chart there is a vertical latitudinal degree scale bar which commences at 26N, finishes short of the charts actual northern edge because of the horizontal scale bar (and is thus drawn after the main chart Wind Rose Graticule) at 55N. It can be extended to 58N which delimits the north coast of Britannia. Inset from this latitudinal scale bar are two further scale bars which from their positioning are to be read contiguously with the latitudinal scale as the southern scale has an exact alignment with the 38N and 42N latitudes and is thus 4 degrees subdivided into 7×5 units, and the northern scale bar aligns from the 44N to the 48N latitudes and has 6×5 divisions for those 4 degrees. The northern scale bar also has a half division spare. Thus from these two scale bars actual measurements can be calculated as occurs later. These scale bars are titled, (south) SPAZIS MYLEN and (north) DUITJE MYLEN. The former is obviously annotated for Spanish Miles, but the latter is in fact annotated for DUCHY miles.

R Amalgia (1952) wrote, “Una graduazione delle latitudini da 270 a 520 e due scale di Miglia spagnole e olandesi [?] sono forse da ritenersi aggiunte inserite piu tardi. {A graduation of the latitudes from 270 to 520 and two scales of Spanish and Dutch miles [?] are possibly to be considered as later insertions}.
The actual chart has degrees from 26 to 55, with the possibility of one more and an extension up to 58 degrees north. If Diagram ChFb/1/D02 of the European ruling elite’s land holding for the period is studied, it can be shown the reference is to the Duchy of Burgundy, the Duke having a fiefdom over the area from 1384 to 1477.
If the chart is studied carefully it can be seen that the ink lines for the latitudinal scale and the two sub-scales are the same, which would indicate they were drawn contiguously and thus in all probability early on in the process as the latitudinal scale bar is an arbiter of the map within the Portolan chart.

The Wind Rose is of basic construction using the 35; 30; 27 graticule that is enlarged on the eastern and western edges by non wind rose divisions. This is to accommodate the fact that Francesco Beccari wanted to produce an 11 ¼ degree alignment using the full 184 tru’s, but unfortunately slightly miscalculated or mis-drew the first vertical alignment. To the east the first major division is 39 tru’s, but the second is 35tru’s with a line 10 tru’s at the edge of the vellum. Thus by simple trigonometry we can calculate that an 11 ¼ angle with a height of 184 tru’s should have a width of 36.68 tru’s. Add the 39 + 35 actual = 74, divide by 2 = 37(36.68) and the error is so simple to determine. The western edge extension suffers the same error and we can assume the calculation by Beccari was slightly awry.

But just how important is it to study the Wind Rose Construction?
On the chart it will be clearly seen that the 37N latitude is a Wind Rose horizontal alignment and the next coincident alignment is the 52N latitude. Thus we have a 15 degree latitudinal measure to compare to the total trignometrical ratio units of those alignments.

Simply put; 15 latitude = c1665Km or c1020 Toscane Miglia (1.633Km)
Wind Rose; 35 + 35 + 30 tru’s = 100 tru’s for 15 degrees latitude.
Resultant; each tru = c10 Toscane Miglia
The inset scale bars, 40 of latitude each have differing divisions of 7 x 5 and 6 x 5    units. The degree of latitude is c111Km geographical.
Thus 40 = 4 x 111Km divided by 35 and 30 units which gives 12.686 or 14.8Km
The 12.686Km is 7.77 Toscane Miglia or 8.5 Genoese Miglia (1.488Km)
The 14.8Km is obviously 10 Genoese Miglia, but also 9 Toscane Miglia.
(It is possible the degree of latitude was 62.5 Miglia, which if Toscane is 102Km.
But if Toscane Miglia, there are 67.21 per degree which is thus 109.77Km.)
Distances; Djerba Isle to El Arisch by Wind Rose Graticule
RTU’s = 8 + 35 + 30 + 27 + 38 = 138 rtu’s
Geographical Distance = c2200Km
Each RTU = 10 Toscane Miglia therefore 138 rtu’s = 1380 Toscane Miglia
and thus; 1380 x 1.633Km = c2253 Km
Distances; Djerba Isle to El Arisch geographical scale bars north and south.
The scale bar distance is 33 ½ units of 5 divisions each;
Thus 33 ½ units = c2200Km or c65.672 Km per unit of 5 divisions;
Thus 5 divisions = 65.672 and 1 division = 13.13Km or 8 Toscane Miglia.
But 8 Toscane Miglia = 2 leagues of 4 Miglia as found on many Portolan Charts from 1311 to 1403.
However, these tables hide a basic fact, that of the actual size of the Wind Rose Graticule and thus the overall size of the chart as drawn. This is fully explained in the section dealing with the actual method of constructing the chart and its inherent errors.

If we therefore return to the e-Perimetron text, page 24, the paragraph discussing the 6th section of the purported methodology we can analyse the errors there-in. The authors have stated that the graticule of the wind rose corresponds to around 50 20’, 40 40’ and 40 00’ degrees. It has been clearly shown that the Wind Rose is set out by a series of trigonometric ratios for the 22 ½, 45 and 67 ½ degree winds and are thus 35; 30; 20; 7 tru’s, and a simple analysis of the preceding text will illustrate its lack of understanding and accuracy. It is tabulated as follows;


Thus by taking each stated division as accurate the other two can be calculated via the ratio numbers and thus the inaccuracy quantified.
If it is converted to geographical degrees the Wind Rose graticule would be 40 00’; 40 27’ and 50 11’, considerably different from the text under examination.



Firstly, the accuracy of the draughtsmanship must be considered as it has an input upon the use of any of the appended scale bars to determine an actual measurement methodology. It has been clearly illustrated that the Wind Rose is a geometrical construct having 35; 30; 20;7 ratio divisions to form the graticule drawn on a Portolan chart. But, measuring the graticule upon the Beccari 1403 chart presents us with an obvious irregularity. The dimensions of the various squares and rectangles vary such that there are three minor variations, but if they are averaged the median measure is acceptably accurate. Thus we can endeavour to use the scale bars to ascertain how the graticule was drawn. But, the two small scale bars adjacent to the latitudinal scale have been cleverly set out with the southern scale precisely 4 degrees long and having 7 x 5 subdivisions, and the northern scale bar being again 4 degrees for 6 x 5 divisions.

Apply these to the Wind Rose and scales appear; the 27 tru square is 4 degrees latitude or 7 x 5 subdivisions of the southern scale, and thus also the 6 x 5 divisions of the northern scale bar. The 30tru square is thus 8 subdivisions of the southern scale and the 35 tru square is 9 ½ subdivisions. Calculated; if 27 tru = 7, then 30 = 7.77 and 35 = 9.07. But the measure was 9 ½ which would give 9 ½ = 35 and thus 30 = 8.143 and 27 = 7.328.

These however are not the easiest of units to mark out via a scale ruler and thus there must have been a simpler solution. This comes from the use of the main northern and southern perimeter scale bars. Using again the TRU’s of 35; 30; 27, we have immediately the measurement for the 30tru square it is 35 scale units (su’s) and thus a simple 6:7 ratio for enlargement. By simple mathematics the 35; 30; 27 tru’s become 41; 35; 31 ½ su’s, which are clearly measurable and easily drawn.

But, that data also provides us with the opportunity to determine the actual measurement of the Wind Rose Graticule. Thus, 41=35=31 ½ = 107 ½ scale units. Those equal 13.4375 degrees, as each degree on the vertical latitudinal scale is 8 scale units. The actual measure is therefore 13.4375 x 111Km = 1491Km. Convert to Toscane Miglia of 1.633Km = 913TM. Convert to Genoese Miglia of 1.4881 Km = 1002 GM.
Thus we can opine that the basic Wind Rose Square for the chart is 2000 x 2000 GM.

The Charts Basic Latitudinal and Longitudinal Configuration;


If the latitudinal scale bar is used to project parallels across the face of the chart it becomes immediately apparent that there are many problems with the slewing of the map within the Portolan in an anti-clockwise direction. This is the norm for Portolan Charts signifying the magnetic deviation indicated by the magnetic compass. It varies chart to chart but is quite often 11 ¼ degrees, or one quarter wind. However it can be clearly seen, even with this tentative investigation, that there are many errors in positioning both latitudinally and longitudinally. These errors will be investigated after the text included by Beccari has been analysed as there are indicators of the problems there-in.

The Appended Text by Francesco Beccari


The chart is perhaps the only one to contain a text concerning the draughtsman and his intentions apropos his chart and states the following (taken from LCP page 461);

Francischus Becharius civis Janue, compusit cartam presentem in civitates Saone (anno) millessimo CCCC tercio, de mense februarii. Qui Francischus notum facit ad tollendam cunctis materiam dubitandi, et omnibus navigantibus et navigaturis mare oceanum protestatur, quod ipse Francischus, in hac et ceteris cartis per eum compositis ab anno Domini MCCC decursso citra, prolong avit distanciam itineris steriarum maris oceani spatio miliarum seu leucarum plusquam ipsemet Franciscus et ceteri magistro cartarum, tam Catalani, Veneti, Januenses quam alii qui cartas navigandi fecerunt temporibus retroactis, soliti errant in eis apponere; et potissime in costa Portugalli, videlicet ad capud Sancti Vincentis (sic) usque a capite Finisterre, et in steria maris seu litorum et locorum Byschaye et costa britanie atque insula Anglie, comperta veritatis essercia de predictis per experienciam efficacem et relationem certissimam multorum numero magistrorum, patronorum, naucleriorum et pilotorum maris Yspanie et illarum parcium, et aliorum eciam peritorum in maris exercitio plurimorum, qui frequenter et longo tempore per illas partes et maris navigarent. Et pro tanto, nullus miretur si de manu ipsius Francischi duarum formarum cartas super hoc dissimiles reperiret, qum ipse ante MCCCC primum aliarum cartae mensuras et magistrorum antiquorum formas et uestigia sequebatur et male.
Eciam, per multos patronos, nauclerios et marinarios sufficientes in arte marinarie michi, predicto Francischo, denunciatum fuerit pluries quod insula Sardinie, que est mari, non fuerat posita in cartis in loco suo proprio per magistros superius nominatos, ideo, in Christi nomine, auditis, posui dictam insulam in presentis carte, et omnibus aliis qui interfuerint, sit notum.”

The translation is as follows;

Francesco Beccari, citizen of Genoa, has written this present paper in the town of Savona, in the month of February 1403. With this written text Francesco wants to dispel any doubts. The ocean and everybody who has sailed the sea are called to be witnesses, that with this paper and the others that he prepared in year 1400, and not before that, Francesco made the route longer in miles or leagues compared to what had been done until that time by Francesco himself and other cartographers, no matter which identity: Catalan, Venetian, and from Genoa and the other cartographers from the past and who were used to opposing to what he (Francesco) said; in more detail such an extension was for the Portuguese coast which means from the Cape of St. Vincent as far as the Cape of Finisterre, for the sea route or the coast of the Bay of Biscay and for the coast of Brittany and for the English Isle. The discovery of the real situation that is stated above was due to the endless experience, a better and more aware skill in the narrating and writing of the very many master craftsmen, friend-patrons, ship-owners, ship-captains in the Spanish sea and the other water bodies and many others who are experts in the knowledge of the sea and have been in those places and surfed the seas/oceans for a very long time and frequently.
We do not need to be surprised to find maps (of the same areas) which are different even to ones prepared by Francesco and concerning the territories mentioned above (the maps show different shapes) depending on the year they were mapped out before year 1400 when maps were drawn according to what the tradition of the old masters had been, even the mistakes.
Furthermore, thanks to the contributions of many ship owners, very skilled ship captains and sailors, I, Francesco, was told in various circumstances that the Isle of Sardinia, the one which is located at sea, had not been placed in its right position by the masters, therefore in the name of Christ, on this present map I have placed the mentioned Isle of Sardinia where it actually is. Therefore you, the owner of this map, are well informed as is everybody else present here



Francesco Beccari has clearly stated that he has altered certain distance measures upon his chart (1403) and “placed the island of Sardinia in the present chart in its proper place, where it actually is”. If Diagrams ChFb/1/D11 and ChFb/1/D12 are studied the variation in the chart to geographical position has been shown with minor differences not quantified on ChFb/1/D11. However, on Diagram ChFb/1/D12, the distances are quantified as they reflect the major points made in Beccari’s text. The coastline of Portugal is still one half degree too short with the error occurring north of Lisbon to Cape Mondego and is reflected in the final positioning of Cape Finisterre, a half degree south of actuality.

Sardinia has been positioned from Genoa for this exercise and in fact was quite accurately drawn in its latitude, but the overall Genoa to Bizerte distance is 80Km too long.



Unfortunately, what this exercise clearly highlights is the major discrepancy in the longitudinal measures of the chart. On Diagrams ChFb/1/D13 and ChFb/1/D14 I have drawn the geographical graticule denoted by the charts positioning of places. In the northern section, Diagram ChFb/1/D13, Ireland has been grossly extended, but Britannia is merely a half degree too short in length. The Bretagne and Cotentin Peninsula’s are slightly north of their geographic position, but the French coastline from Biarritz to Bretagne is actually very accurate.
In the south section, Diagram ChFb/1/D14, the geographical graticule indicates the errors with France at the Pyrenees; it is vastly extended and thus Iberia is affected also. The North African Coast is expanded between Tangier and Bizerte as the varying longitudinal degrees indicate, with the latitudinal degrees indicating a similar spread.

But, we must not let the above critique indicate anything more than a comparison of the chart to a geographical map. It is extraordinarily accurate for its age and the draughtsmanship is exemplary, even though there are signs of drafting problems; it is a superb chart of its genre.




It is assumed the Battista Beccari is a relative of Francesco Beccari, and that he continued a cartographical style established c1400AD. There are two charts which are attributable to Battista; the first, as ChFb/1/D15, is dated 1426, signed as follows; “Baptista becharius civis Janue composuit hanc cartam anno domini millex. O CCC XXX de mense novembris ad requisicionem et nomine—–“, and is held by the Bayerische Staatsbibliothek, Munich, Germany, reference Mapp. XXV, ly.; the second, as Diagram ChFb/1/D16 is dated 1435, signed as follows; “—- a Becharius civis Janue composuit hanc —- anno domini Millexio ccc.xxxv de —- jullij”, and is held by the Bibliteca Palatina, Parma, Italy, reference II, 21, 163.


This latter chart is featured in Les Cartes Portolanes, C39, pages 252/253 and is the main subject of investigation and comparison. It is Diagram ChFb/1/D17. Restricted to the western Mediterranean Sea for actual navigational purposes, it includes in the Atlantic Ocean imaginary islands such as Antillia, Satanazes, Royllo and Tanmar, which do not apopear on his 1426 chart. There are several cities depicted in vignettes, Genoa, Avignon, Santiago de Compostella and Tlemcen as the 1403 chart shows, which was sized 89 x 139.5cm. The 1426 chart is 68 x 103.5cm and the 1435 chart is 65 x 89cm.


he 1435 Portolan has a single Wind Rose with normal extensions east and west of 35tru, the main square of the Wind Rose Graticule. The Atlantic Islands are situate upon the western graticule extension line.
Rather than a long discourse upon the actual scales and their measurements, Diagram ChFb/1/D18 represents the two charts, 1403 and 1435, overlaid with the 1403 charts latitudinal and inset scales appended as well as the southern and northern perimeter scale bars. Thus we can surmise they are from the same template, drawn 30 years apart, and slightly enlarged.


Upon Diagram ChFb/1/D19, there are the same two charts overlain with all scale bars drawn. The difference between the two maps within the Portolan is illustrated by the fact that on the 1403 chart, c15 degrees latitudinal scale represents 35tru + 35tru + 30tru = 100tru, where-as on the 1435 chart the c15 degrees equals 35tru + 30tru + 27tru = 92tru, the actual Wind Rose Graticule. This I can opine that Battista Beccari chose to draw his Wind Rose Graticule based upon a c30 degree latitudinal scale, that is 30 x 111Km = 3330Km or 2240 Genoese Miglia, where-as Francesco Beccari had utilized an overall graticule of 2000 Genoese Miglia.

The problem of chart accuracy in draughtsmanship does of course play a large part in assessing the drawn scales. That is not to say they are actually inaccurate, just that the minor deviations of drawn lines and minor measurement changes of the graticule NSEW (ignoring shrinkage/stretching of the vellum) means the data taken from the charts can only be an average measurement.

Thus the Beccari School of Genoa produced Portolan Charts from c1400 to c1435 of simple design, largely unadorned for ease of reading the toponyms and utilisation of angles, and of an accuracy which should be applauded given the age when they were drawn. However, the longitudinal errors surely must have been noted by the Seamen, particularly the North African coast expansion and even the route from Genoa to Bizerte at 80Km excess.


It would be churlish to criticize because of the data that has been abstracted from these charts. But, the fact that Francesco Beccari clearly states he has remedied errors, which in all probability were in response to criticism of one of his earlier charts, shows that good latitudinal measurements were available c1400AD, which should have determined that the 1403 chart was drawn “geographical” from the Atlantic to the Black sea.
Why are the correct geographical latitudes only applicable to the Atlantic seaboard of Europe?
Why do they not apply to the Mediterranean Sea and Black Sea areas?
Surely it is a dichotomy of grand proportions that the latitudes were not recognised as false.

M J Ferrar December 2014.



1) Diagram ChFb/1/D20 is a copy of note 27 regarding the exchange of letters by Francesco Beccari and is taken from page 430 of Les Cartes Portolanes. They amplify the text already quoted and translated regarding the 1403 Portolan chart.
2) Shedding the Veil: Mapping the European Discovery of America and the World; a book by Thomas Suarez, published by World Scientific in 1992.
Chapter 4; The western Antipodes, section 9, Portolan Chart.

In a fashion of the more elaborate Portolan charts Beccari has adorned the otherwise void inland areas of his chart with vignettes of the cities considered most important by him, the most prominent being his native (?) Genoa. Others are; Venice, Genoa’s perennial rival; Santiago de Compostella, in NW Spain, the most important place of Pilgrimage in Medieval Europe after Jerusalem and Rome; Marseille, an important commercial centre and a departure port for the Crusades; Cologne, commercial cemtre and river port; Cairo, seat and Egyptian control over Levant trade; and ever important Jerusalem. The remaining two are the least familiar to modern eyes. One is Varna lying on the shores of the Black Sea. Varna had been captured by the Turks in 1391, and by Beccari’s time had become an important Ottoman port. Within a decade of this chart, 1444 Varna was the site of Europe’s final offensive defeat in her battle against the Ottomans, with her loss of the Near East soon to be consumed by the fall of Constantinople in 1453. The remaining metropolis is Fez (Tirimissen offset to the east) which for Europe was perhaps the most fabulous and exotic of these cities depicted in vignette. Founded in 808AD, in Beccari’s time the new city of Fez, connected by walls to the old, had been built, and Fez had already reached its greatest glory under the Marmid Sultans of the 14th century. At the time of Beccari’s chart, Fez had taken on particular significance for Europe because of its proximity to Ceuta, whose conquest by Portugal in 1415 marked the first permanent European foothold in Africa and the beginning of European overseas expansion. Below Fez, along the bottom of the chart, an inscription explains that the regions to the south consists of deserts and great forests and is inhabited by black people.

Little is known about the maker Battista Beccari. On this chart the vignette of Genoa is clearly more prominent than any other, suggesting that he worked in or at least considered his allegiance to be to that city state. That Battista worked in Genoa is also strongly supported by a document which recently surfaced (79). This document is a contract in which Battista, residing in Genoa, agreed to apprentice a 9 year old boy Raffaelino Sarzana in the art of making charts for a period of 8 years. The document is dated August 17th 1427, placing the end of Raffelino’s apprenticeship at 1435, just after the tentative date assigned to this Portolan chart.”
77) Tony Campbell, Portolan Charts from the late 13thC to 1500. HOC, p431, n415.
79) Battista’s accentuating coasts by colour was first noted on his Portolan of 1426 (Bayerische Staatsbibliothek, Munich), The improved charting of Atlantic distances and of Sardinia were apparently introduced in a 1403 chart of the elder Beccari. In an inscription on this chart he explains that owing to complaints and advice from seamen he has lengthened Atlantic distances and adjusted the position of Sardinia.
Francesco’s address as translated in H P Krauss catalogue 95 (1961) states in part that;
Francesco Becharius—in this and other charts— from after 1400AD, lengthened the distance of the coasting navigation—-especially in the coast of Portugal viz., from Cape St Vincent even to Cape Finisterre, and —- Vizcaya and the coast of Bretagne and of the Island of England—-the marrow of the truth  having been discovered concerning these (things) aforesaid through the efficacious experience and most sure reports of many, i.e., masters, ship owners, skippers and pilots of the seas of Spain and those parts and also of many of those who are experienced in sea duty, who frequently over a long period of time sailed those regions and seas—–(therefore) I placed the said island (of Sardinia) in the present chart in its proper place where it ought to be.”

The improvement had been noted on a Battista Portolan of 1435 (dated 1436) in a report by Herman Wagner, published 1895, well before the discovery of Francesco’s earlier chart with its explanation.

Thus the story comes full circle and the date of 1435 is explained as perhaps the end of it all.

M J Ferrar December 2014.

Philipp Billion, 2013. “How Did Medieval Cartographers Work?  CFC, No216, Juin 2013, pp 33-45..
Lepore, Piccardi & Pranzini, 2012. “The Autumn of Medieval Portolan Charts. Cartometric Issues”. e-Perimetron, volume 7, No 1, 2012, pp16-27.
Ferrar, Michael. 2014. Wind Rose Construction.
Almagia, R. 1952. “Intorno ad alcune carte nautiche italiane conservate negli Stati Uniti.” Atti Accademia Nazionale dei Lincei, Rendiconti Classe di Scienze Morali, Storiche e Filosofiche, serie VIII, VII, 1952 p356-66.