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The Atlas is an amalgam of disparate pages varying from a Ptolemy style world map, a circular configuration of star signs and known planets, a Portolan Chart and a beautifully rendered sheet containing the Armorial Bearings of the House of Aragon and a detailed single map of Corsica, their fiefdom. The actual charts cover the Mediterranean Sea Basin and N Africa’s west coast to the equatorial line. They are described by the JCB Library, who hold the atlas and have lately dis-jointed it to enable a superb set of scans to be produced for study purposes. They are as follows;
08658-001; Dedication leaf and map of Corsica
08658-002; Portolan of West coast of Africa from the Tropic of Cancer to 17S, including the Cape Verde Isles and the Atlantic Islands of, Sao Tome, Principe and Annobon
08658-003; Portolan chart of N Africa, Europe and parts of Asia
08658-004; Portolan chart of the Atlantic coast of Africa and Europe, the British Isles and Iceland, including the Canary Isles, Madeira and the Azores
08658-005; Portolan chart of the Greek Isles and the Aegean Sea.
08658-006; Africa, Asia, Europe and the NE extremity of the New World
08658-007; Portolan chart of the Western Mediterranean Sea
08658-008; Portolan chart of the Eastern Mediterranean and the Black Sea
08658-009; Portolan chart of Italy as far as the mouth of the Tiber River, Western Sicily and the Adriatic Coast
08658-010; Cosmographical planisphere

ChAVM/1/D01 ChAVM/1/D02

ChAVM/1/D03 ChAVM/1/D04

ChAVM/1/D05 ChAVM/1/D06

ChAVM/1/D07 ChAVM/1/D08

ChAVM/1/D09 ChAVM/1/D10

The Atlas as described was somewhat nonsensically set out as will be clearly demonstrated by the conjoint charts. The Portolan charts of the western (007) and eastern (003) Mediterranean Sea, are drawn to the same scale and obviously meant to conjoin.

The Portolan chart of the Atlantic Coast (004), if it had been drawn to the same scale as the above charts would have provided for a complete Portolan Chart incorporating most of sheet 004. That it has not is obviously to include the northern areas missing from the others on the same size of sheet and thus required a reduction in scale to achieve that chart.

The Portolan Chart of the western Mediterranean (008) is drawn at half scale to the sheets 007 and 003 and is in fact the complete Portolan chart incorporating most of 004.

It is therefore self evident that Vesconte Maggiolo would have composed his 10 sheet Atlas as follows;
08658-001; 008; 002; 004; 007; 003; 009; 005; 006 and 010.

The sheets are double page and thus are c39 x 55.6cms (i.e. 2 x {39 x 27.8}) with sheet 010 being the cosmography occupying only the left hand side of a double sheet width.

Hence it is necessary to commence this investigation into the inner workings of the Atlas with the logic of the charts themselves as numerated above. That is with the exception of sheet 08658-001, Dedication and Map, which requires special attention as its design and purpose has eluded scholars previously and text ChAVM/2 examines it in detail.

SHEET 08658-008

In text ChGEN/1, Genoese Charts, I opined that the 1511 Atlas could not have been drawn unless Vesconte Maggiolo already owned or had drawn a full Portolan Chart to enable the sub-parts of the Atlas to be properly composed. This sheet 008 is undoubtedly a reduced version of that Portolan Chart, it being only c39 x 55.6cms, where-as most full Portolan Charts vary from c50 x 98 to c85 x 125cms, with c60 x 100cms being a median and thus 1 ½ times larger than the Atlas page. No doubt by using a scaled down Wind Rose graticule and proportional compasses this would have been a task that Vesconte Maggiolo could easily accomplish. The scaled down wind Rose graticule is a simple mathematical exercise. VM has drawn four squares in the centre of the sheet each scaling 1100 x 1100 scale bar units or Miliaria. But a wind Rose comprises 92 units per square, subdivided into 35/30/20/7 units. Therefore a simple calculation shows that, 92 x 12 = 1104 units for the main squares and 1200 units for the longitudes and 550 units (ie ½ x 1100) for the Latitudes. A very cleverly set out Wind Rose graticule keeping to the original design set out by Petrus Vesconte in his 1318 Atlas.(Text ChPV/1)

That points to a simple conclusion that this chart probably gave the double page size for the complete atlas and thus each new section was scaled to suit that page size.

An in depth study of sheet 008 has been carried out and to avoid duplication of effort the chart has been enlarged to match the scale bars of sheets 007 and 003, (the Mediterranean Sea basin) and as indicated previously it had to be enlarged by 200% as the scale bars are a 1:2 ratio. The enlarged sheet 008 is portrayed on 4, A4 sheets which overlap to form the whole chart, and then the next four sheets have the putative latitudes and longitudes appended.

Later in this text sheet 008 will be compared to sheets 007 and 003.
But, I find this rather strange as when in the later sections of this text the 1512 Portolan by Vesconte Maggiolo drawn in Naples as is the Atlas is examined, it does not contain all of the above Atlas charts information; why?






The chart is drawn to the same scale as sheet 008, the main portolan chart and thus could be conjoined to form one chart representing the knowledge of the Portuguese mariners c1480. It exhibits the same scalar enlargement of the Gulf of Guinea as can be seen on the 1500/1505 charts by J de la Cosa, Cantino and Caverio, from 17W, Cape Verde to 10E Equatorial Guinea. The 27 degrees are basically c95 miliaria, but considering the fact that the Equatorial longitude degree is 90 miliaria this could be an attempt at a correct distance which is marred by the fact that the degree of latitude is not 90 miliaria but as indicated with varying measurements per degree. I suspect this is a distance measure longitudinally given by the first draughtsman of a chart of this area but the relationship was not explained between the two differing degrees, latitude and longitude.

The wind rose graticule is formed from a 1530 miliaria square and is drawn as 580/500/450 for the 35/30/27 proportional sections but Vesconte Maggiolo has omitted the 35/30 line from the plot.







This chart has been drawn at 9/11th scale of sheets 007 and 003 to which it should and could be joined to form a whole Portolan chart as sheet 008. The wind rose has been set out using four squares of 920 miliaria and emulates sheet 008 perfectly. The latitudinal and longitudinal measurements are appended to the plot and it shows that the Islands including Iceland are correctly positioned. Unfortunately the mysterious islands of the Atlantic are still noted, Isla de Brazill and Isla de Maida.




This chart is a full portolan chart showing the Mediterranean sea from the Pillars to the Peloponnese with many cities/ports indicated by the Flags of their affiliations. Seville is flagged by the Arms of Aragon/Castile as are the African Cities of Oran and Bugea, but they are surrounded by Muslim Flags and is probably the most up to date information that could be put on a chart or atlas by V Maggiolo for his client. Barcelona is flagged for Aragon as is Naples with Rome having its Keys. But mysteriously the flags of Sicily, Sardinia and Mallorca have been erased, no doubt at a later date when allegiances changed. However Corsica and Genoa are flagged for St George and curiously as will be seen later on sheet 009, Sicily is flagged for Aragon, as is Naples, but both using older flags, c14th century.

Oran was captured by the Spanish under Count Pedro Navarro on the orders of Cardinal Cisneros on the 7th may 1509, Castile and Aragon having been united by the marriage of Isabella 1st of Castile and Ferdinand 2nd of Aragon in 1469. Oran was held by Spain until1708. Portugal had tried in July 1501 to take Oran but failed to do so. Thus the multitude of flags in N Africa illustrates the ever changing allegiances and ownership.

The wind rose of the chart is set out correctly and proportioned from a 790 miliaria square and thus the subdivisions are 300/260/170/60 miliaria.

The latitudes and longitudes are the basic Portolan Chart units with the longitudes being 72 miliaria at 36N reflecting the 90/72 ratio of the latitude.





This sheet is the same scale as sheet 007 and they overlap to form a continuous Portolan Chart from the Pillars to the Black Sea. But, whereas sheet 007 has numerous Flags appended this sheet is devoid of attribution except for the Islands of Rhodes and Sio (Chios or Scio) which both have a standard cross within.

The wind rose graticule is the same as sheet 007, but has been slightly miss-set on the sheet in the west such that it encroaches upon the bordure. The latitudes and longitudes are commensurate with sheet 007 and this is clearly illustrated on the conjoined plot.






This sheet is a complete mystery in that the west coast of Italy finishes at Rome and is opposite on the east coast to Ravenna, but continue that line and further on at the northern extremity is Venice. Thus the whole east coast has been compressed to place Rome and Ravenna opposite each other when they are basically a north/south alignment and thus this sheet 009 should be read from Sicily in the south that is turned through 90 degrees to emulate the geographical plot. Geographically Rome to Ravenna is 280km (nearly due north) or c230 miliaria and it actually scales 220 miliaria with Venice geographically north by 110km or 90 miliaria but is drawn as 150 miliaria. As commented previously the two fags, Naples and Sicily are correctly drawn and date to the 14th century for Aragon.

The scale bar is actually 200 miliaria in length and if equated to sheet 007 which has a scale bar of 550 miliaria it is an 11:4 increase in scale but uses the basic 11 unit as sheet 004 which is 9:11 scale of sheet 007.

The wind rose graticule is 570 miliaria overall and can be interpreted as 110/95/60/20 calculated from 108.4/92.9/61.96/21.68 for ease of setting out. However using the scale bar the overall sheet size c39 x 55.6cms is in fact 600 x 850 miliaria and thus perhaps the 11:4 ratio increase in scale is set by the sheet itself and not chosen as a proportional increase.





This sheet is the twin for sheet 009 in that it uses the same 11:4 larger scale bar and is in fact a latitudinal chart that should be read turned through 90 degrees as sheet 009. But of course this time the 90 degree turn is opposite, as the chart is drawn to be read mostly with the north and scale bar in the south position; most confusing and unnecessary as the coastal toponyms follow the usual circular pattern written away from the coastline but the toponyms for the islands are counter written.

Devoid of major embellishment, Rhodes has the Cross form but Sio does not; Crete has Candia drawn as a vignette (the un-named Iraklion) and Neigro Ponte (Evvoia-Euboea) has the un-named Chalkis as a vignette.

Unfortunately the sheets 005 and 009 do not join as the section from Corfu to the Gulf of Delphi is missing. The wind rose setting out and hence the sheet size at 600/850 miliaria is as sheet 009. The typical Portolan Chart problem of the latitude of the Aegean sea is clearly exhibited, but perhaps not as pronounced as some charts which have a clear 5 degree distance measure for 36/40N.





The first two diagrams comprise an overlay of the sheet 007 plot to the sheet 008 plot and then the sheet 008 plot to the sheet 003 plot.

Naturally scale adjustments have been made to allow these comparisons to be made, but they do indicate a reasonable compliance to what may be considered an original Portolan chart master copy.

The second set of comparisons, 4 sheets, compares sheet 008 to the Vesconte Maggiolo 1512 Portolan chart drawn in Naples and held by the Hispanic Society, USA, as reference K33. On these plots we see a gradual expansion of the chart to the east in the central areas, but the West coast of Iberia and the east Coast of the Black sea (sheets 1 & 3) commence and finish correctly. Bear in mind, that the K33 Portolan is a much larger chart than sheet 008 which although only c39 x 55.6cms has a much larger land area drawn there-on. However, the K33 chart has adequate space left void to include much more in its NW quadrant should Vesconte Maggiolo have desired so. I have previously commented that I find this rather strange as the Atlas has far more information and I think it would normally have been included, but perhaps the chart was curtailed in its drawing time.




As with many other Ptolemaic projections, pseudo or not, this chart is an amalgam of the latest data available for Europe, Africa and the West Indies joined to the Ptolemaic portrayal of the Middle and Far East. There is latitude to longitude expansion of 1:1 ½ and the Mediterranean Sea length from Ptolemy’s zero longitude point is upheld at 70 degrees, although the zero point is repositioned. The latitudes from 35S, Cape of Good Hope, S Africa to 40N, Central Iberia are quite well positioned but the “Climata” setting out is seriously awry as shown by the Red (original) and Green (correct) positions apropos the latitudes drawn.


The West Indies and S America are a mixture of good and indifferent positioning. For instance Isabella (Hispaniola) stretches from 68W to 74W and on the Vesconte Maggiolo chart taken from the pseudo Ptolemaic setting out it is drawn 60W to 75W. The East coast of S America is however on the same basis positioned 35 degrees to the east; Cap de Sao Roque is set on the pseudo Ptolemaic zero line and should be 35W. Thus with Trinidad and Tobago set at 43W (63W actual) the whole coast has been unnecessarily extended.

To the North we have the Portuguese lands of Corte Real, etc, which co join to the curiously named peninsula of Scandinavia circulating around the N pole. The basic construct is similar to the J de la Cosa, Cantino and Caverio portolan Charts.


The planetary chart with star signs of the ecliptic set out from the junction of Sagittarius and Capricorn or Gemini/Cancer, north or south, has in the east and west the equinoctial dates of Pisces/Ares and Virgo/Libra. The star sign distance around the ecliptic is drawn as the perfect 12 x 30 degree segments where as they vary from 19 to 45 degrees span. However the semicircles when drawn correctly are 182/178 degrees with quadrants of 101/81/89/89 degrees and apart from Virgo and Libra spoiling a near perfect layout of 4 x c90 degrees the concept is sound. When exactly the Age of Aquarius begins is still hotly debated.



These nine sheets of the atlas as charts etc are a fine example of the genre, well drawn and labelled and I am sure would have been set out in the order I have suggested to enable the recipient to study and follow the logic of these charts and their information.

There does not appear to be any surprises within them, although they are somewhat out of date for 1510 as many other charts will clearly show. That raises the question of what information Vesconte Maggiolo was able to bring with him from Genoa and when he actually left Genoa, thus in all probability He only received written or verbal updates such as the capture of Oran in 1509. The 1512 chart is quite telling in this instance as it shows even less data than included on the Atlas pages and could be a basic chart to be updated.

The fact that the Atlas has been altered in the distant past precludes major comments as we just do not know if we are viewing the original number of sheets or why the alterations to some charts was made. As suggested, loyalties changed and fiefdoms altered.

M J Ferrar October 2019.