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Diego Ribeiro is in fact Portuguese and moved to Spain to produce charts and technical instruments for the Casa de la Especiera c1519 and then for the Casa de la Contratation in Seville, c1523. He was appointed “cosmografo y maestro de hazer cartas y ostros ingenious para la navegacion” at a yearly salary of 30,000 marevedis. He also designed a metal pump system which “He Promised” would draw a barrel of water with only 10 strokes.

The appointment to the Casa de la Contratacion was on the 10th July 1523, and he was also part of many “Juntas” and finally died in Seville, 16th August 1533.

In 1508 and again in 1512 the King of Spain ordered by Royal Cedula that a Padron Real be kept up to date in the Casa de la Contratacion so that information carried home by various expeditions would be immediately used and available to the next expeditions. Thus many “Pilots Maior” were charged with this task and we read that it was permissible for copies to be made and sold to enable those future expeditions to have the latest knowledge.



That of course begs the question as to why some researchers write that the Padron Real was secret; the “permis” seems to obviate that statement, but possibly it was for copyright only.

Hence the work of Diego Ribeiro is considered to be a “copy” of the Padron Real with its updates as the five planispheres clearly indicates. However the two charts chosen for study in this text are also adorned with drawings of instruments and a table to establish the declination of the sun at particular latitude as well as establish those latitudes. Longitude was still a time and speed measurement and of course so manipulated to be anything the two sides of the “junta’s” wanted to portray.

But it is also obvious that Diego Ribeiro used the Suma de Geographia printed in Seville in 1519 and thus the text commences with a discussion of that text and its influence.

The geographical text written by M F de Enciso was published by Jacobus Gronberger in 1519 and is the first printed in Spain in Spanish covering the discoveries in the Americas. Enciso spent several years in the Caribbean and thus his practical experience and theoretical knowledge could be combined into a Pilot Manual and compendium of “world” geography. It is possibly the most complete geographical and navigational tract of its period.


From page 18 (of 150) Enciso commences with a list of the months, their Saints Days and declination per day. It is named “Declinacio di Sol”, the days are numbered per month and a heading “Gradus, Miutos” is used for the declination readings. Interspersed are the Star Sign change dates. In fact after these first pages of singular months, there are three more lists of Declination with minor typo errors included. One of these tables is now illustrated here-in and the system can thus be understood.


But on page 42 we have a very definitive measurement for a degree of latitude given as “xvij leguas y media”; that is 17 ½ leagues per degree. That measurement is then used in a similar manner to some Marteloio to produce a table of distances required to sail and thus achieve one degree of latitude when sailing at one of the 7 points of 11 ¼ degrees off course.


Tabulating the distances given we read at NSEW = 17 ½ leagues and then
11 ¼ = 17 ¾; 22 1/2 = 19 1/6; 33 ¾ = 21 1/3; 45 = 24 ¾; 56 ¼ = 31 ¼; 67 ½ = 46 ½ and 78 ¾ = 87 1/6th leagues. The actual distances are tabulated for comparison;
11 ¼ = 17.8428; 22 ½ = 18.9419; 33 ¾ = 21.o471; 45 = 24.7487; 56 ¼ = 31.4992; 67 ½ = 45.7297 and 78 ¾ = 89.702 leagues.
The distances off course for each 11 ¼ degrees are as follows;
11 ¼ = 3.481; 22 ½ = 7.249; 33 ¾ = 11.693; 45 = 17 ½; 56 ¼ = 26.191; 67 ½ = 42.249; and 78 ¾ = 87.978 leagues.


But of course M F de Enciso did not have an electronic calculator or an accurate table of Cosine/Tangent/Sine and what medieval mathematicians had to grapple with were fractions and the Marteloio tables give us an idea of those. The Wind Rose is split into four sections with a constant proportion per quadrant of 35/30/20/7 units in a 92 x 92 unit square. Thus we can assess the Tangents of the three main angles as Tan 22 ½ = 35/85; Tan 45 = 92/92 and Tan 67 ½ = 85/35. But Tan 22 ½ = √2-1 and Tan 67 ½ = √2 +1 and as √2 = 99/70 then Tan 22 ½ = 29/70 and Tan 67 ½ = 169/70.

Using Marteloio figures we have;
20/98 = 11 ¼ (11.31 actual) = 7/35 or 1/5
38/92 = 22 ½ (actual 22.38) = 35/85 or 7/17
55/83 = 33 ¾ (actual 33.69) = 18/27 or 2/3
71/71 = 45
83/55 = 56 ¼ (actual 56.31) = 27/18 or 3/2
92/38 = 67 ½ (actual 67.62) = 85/35 or 17/7
29/20 = 78 ¾ (actual 78.69) = 35/7 or 5
The reasons for explaining these units in depth will become so very clear when the charts are assessed and Diego Ribeiro’s figures are shown.


However, study the declination tables and we find that M F de Enciso has noted the following for the Equinoctial and Solstitial days. (Please note calendar changes require that 11 days be added for 21st century dates). The Spring Equinox is given very clearly as 11th March; the Summer solstice is given as 13th June; the Autumn Equinox is either 13th or 14th September and the Winter Solstice is given as 12th December.

Thus we have; Spring E to Summer S = 21+ 30+31+12 = 94 days
Summer S to Autumn E = 18+31+31+12 = 92 days
Autumn E to Winter S = 18+31+30=11 = 90 days
Winter S to Spring E = 20+31+28+10 = 89 days.

Today with our very accurate measurement systems we can actually determine the range of days on which the Equinoctial and Solstitial days will fall. But, given that an Astrolabe does not have the capability of very fine readings differentiating the minor changes at each, sometimes minor parts of a degree over three to five days of possible precise date we must look carefully at the 1519 data and understand just how much deviation it would make for a reading of latitude etc. The tables show the problem with the declination readings there-on.

Today the dates would be as follows;
Spring Equinox; 8-9-10 March ; (19-20-21) or 20th March
Summer Solstice; 9-10-11 June ; (20-21-22) or 21st June
Autumn Equinox; 11-12-13 September ; (22-23-24) or 23rd September
Winter Solstice; 9-10-11 December ; (20-21-22) or 21st December
which gives the days for each as 93/94/89/89 = 365 days.

But M F de Enciso also states regarding the Regimento del Astrolabio y Quadrante that six months are above the Equinoctial Line and six below. This in effect introduces another variable to the possibility of drawing the Declination Table on the charts. Hence with March to August given as above the line we have 184 days, and below the line from September to February we have 181 days. This is so very significant when analysing the Declination Diagram using the written instructions on the 1529 chart.

Thus the text of MF de Enciso indicates two possible scenarios for drawing the declination diagram. Using their actual Equinox/Solstice spacing of 187/178 days but drawing the Equinoctial points opposite each other on an equatorial line will mean the southern portion is incorrect and any utilisation will give fallacious readings as the later text clearly illustrates when the diagram is fully analysed. The diagram illustrates the problem clearly.

Finally, before turning to an investigation of the charts there is one point which must be examined, that is the 17 ½ leagues per degree. Portolan Charts are generally drawn with a Miliaria Scale of 90 per degree as has been clearly shown in the previous texts. There was generally a problem with the West Coast of Iberia drawn as six degrees (37/43N) of 75 Miliaria per degree shown to be a complete error in transcription from 75 Roman Miles per degree, an accurate figure, to 75 miliaria and hence the slewing of the Portolan Charts. Thus 17 ½ leagues is therefore 5 1/7th miliaria per league (6.339KM) or 4 2/7ths Roman Miles per league (6.339KM). A note in the Dictionary of Measures reads thus;

La lieue juridique ancienne, legua legal, abole en 1568 par Philippe II, se divisait en 3 millas ou milles = 24 estados ou stades= 3000 pasos ou pas geometriques = 5000 vares = 15000 pieds (4.175km)

La lieu geographique de 17 ½ per degree, rendue obligatoire en 1718 par Philippe V, pour regler les echelles des cartes geographiques = 7605 Vares -= 28815 pieds or 6.3505 KM.

It appears in 1519 the problem had already been solved and just required confirmation as the difference is 0.0115km or 11.5 metres, 13 ¾ vares and impossible to quantify at sea. But of course it had to be quantifiable in total and easily so such that measurements could be made generally by speed and distance measured on the rail of the ship or by a line drifting out for a known distance. Thus it must be assumed the 17 ½ leagues was a simple whole number of Vares or Pieds such that the calculation was simple on board a ship. Thus the new figures are perhaps rather unwieldy for usage on a ship and it makes for a very short pied of c220mm.

Here ends the general discussion of the text of “Suma de Geographia”.




The planisphere is formed from four pieces of parchment joined to produce an overall size of 815 x 2140mm and is, when compared to the other charts a rather bare edition. It has three latitudinal scales which delineate the Equator, the Tropics and the Arctic and Antarctic circles and thus produce a basic 70 degrees overall north and south of the Equatorial line. There are two wind rose hidden circles formed by the graticules and the notional radius is c72 degrees. As the circle is not drawn, it is perhaps set out from the graticular points of the 22 ½ degree sections at 66 ½ degrees latitude. Thus the triangle formed as the diagram illustrates is a simple 72/ 66 ½ /29.82 (30) degree construct. But reduce the radius of c72 to the basic wind rose units of 35/30/20/7 and the calculated distances are 27.39; 23.48; 15.65; 5.48 degrees, with the discrepancy between 29.82 and 27.39 degrees. However as the Planisphere is terminated at the Circulo Arctico and Circulo Antarctico, that is 66 ½ degrees north/south, the first proposition for the triangle is probably the correct one.


The Equatorial line is marked out with five degree subdivisions and spans from c213 west to c168 east. There are also three vertical scales having three divisions of 8 units each, thus 24 overall but measuring 17 degrees on the latitudinal scale Was it meant to be 17 ½ ?

Dealing with that fact first, we can immediately recognise the Roman influence from their surveying measures in that their standard unit is 12/12/17 (120/120/170) squares and of course 17√2 = 24.04 units and 17÷24 = 0.71 ie √2÷2, and the 71 0f the Marteloio.

At this juncture it is worth pointing out that in the south, virtually central on the sheet is a missing circle shown where the wind rose lines terminate to form a circular outline. It measures 24 degrees diameter and hence 12 radii and I suspect was to be an explanatory diagram for the various measurements on the chart. But an alternative does exist.


However, it does point to one fact that this chart is not completed and may well have been intended to visually match the following charts. It is also possible that it was given prior to completion by or on the orders of King Charles V to Baldassarre Castiglione (1478-1529) Papal Nuncio in Spain who was about to depart. But by not being complete it does raise more questions than can be answered here-in.

Study the latitude/longitudinal scales and it becomes so very apparent that they are precisely the same and hence this Planisphere is a SQUARE CHART, which of course leads to the conclusion that the PADRON REAL was a SQUARE CHART also. The proof is clearly shown on the diagrams, but in studying the Mediterranean Sea area the proof is absolute. Align Cape St Vincent (37N-9W) to the Equatorial scale degree marks and it is “5” degrees east. Then align the Gulf of Issus (36N-36E) to the same scale and it reads 50 degrees east. Hence the Mediterranean Sea has been drawn with the 36N latitude parallel to the Equator, thus negating any idea of a magnetic slewing, and of course it means the overall length from Cape St Vincent to the Gulf of Issus is a perfect geographical measurement of 45 degrees. It is a SQUARE CHART, NO MYTHS required!

Now study the Flags of Spain and Portugal set along the southern edge of the chart. In the west the Spanish flag aligns to the 210 degree marker and in the east to the 150 degree marker; i.e. 360 degrees circle. But centrally the Line of Demarcation is set at 30 degrees west of the zero longitude marked on the Equator and which is aligned to the West African Coast. Thus the Cape Verde Isles are in the extreme 9 degrees west and the Line of Demarcation a further 21 degrees west. And, to ensure the Moluccas, the Spice Isles are within the Spanish half they are drawn twice and the “Province de Maluco” is set at 158 east/202 west (360 degrees). A rather good sleight of hand and to no avail as soon after this and bearing in mind the long drawn out discussions to determine these longitudes, the King of Spain sells the Spice Islands to the King of Portugal. There was no bigger waste of time!

The geography of the chart itself is a snapshot of discoveries made from 1492 onwards for the America’s, but much earlier for the Portuguese explorations of Africa and India. The fact that South America is terminated at 53 degrees south, the Strait of Magellan discovered in late 1520, and the fact that the exploration of 1525 to America is included indicates the speed with which the Padron Real was updated. That is confirmed by the text appended to the N American section which reads, “Tierra que descubrio Estevan Gomez este ano de 1525 por mandado de Su Magestad”. From India to S E Asia was penetrated between 1512 and 1516, and the size of Africa was actually known from the position of the northern area of the Red Sea close to the River Nile. Portolan charts from as early as 1339 indicate this positioning very clearly and hence this is a deliberate act of falsehood with Africa drawn 14 ½ degrees longitude wider than geographical reality. But, reduce Africa to its nominal 68 degrees width and place the Moluccas at 125 east Geographical, that is 140 degrees from the chart zero and they are within the Portuguese half of the world as divided by the Line of Demarcation. The overlay to the chart has the actual geographical Longitudes and Latitudes appended for reference.

Various readily available texts have a full description of the Castiglione Planisphere.








The Vatican Library 1529 Planisphere by Diego Riberio varies little to the geography of the 1525 Castiglione Chart. The marginal differences can be seen in the additional west coast of South America and the firming up of the shape of the “Golden Chersonesus” and Sumatra. The main difference is the plethora of texts appended across the chart not only describing the geography but the technical data required to inform mariners of the instruments drawn there-on. It is also luxuriously covered in drawings and sketches and has an enhanced wind rose system of graticular lines based upon latitudes.

The two Flags set atop the Astrolabe are curiously positioned in that the Spanish Flag does not quite line up with the 150 degree longitude to give 360 degrees from the western Flag. It is drawn at 148 east and has the Portuguese Flag set at 135 degrees east. It is obvious this is a complete draughting error stemming from the wrongly positioned “Provincia de Maluca” set at 188 west before the actual “Provincia de Maluca” set at the matching 202 degrees west. This is precisely the 14 degrees error in the African Continent mentioned previously with an error in the flag positions of 13 degrees.

The scale is commensurate with the 1525 chart as we should expect, but the three small vertical scales are drawn two thirds size of the 1525 chart at 16 units in length but drawn in a cartouche that is capable of including 24 units and is therefore probably just a change of mind, or error as with the double “Provincia de Maluca”.

The overlay plot notes the possibility that the 30 degrees west of Cape Verde for the Line of demarcation could be construed as 21 of the small bar units and mathematically we have 30÷√2 = 21∙21 and perhaps is an attempt to use the measurement given by Jaime Ferrer to the position of the Line of demarcation at 20 5/8ths. Scaling from these charts is fraught with difficulty when obvious errors can be detected and the accuracy achieved by Diego Ribeiro in his draughtsmanship cannot be equated to today’s methods. But, suffice it to say latitudinally it is an excellent rendition of the geographical world and if actually completed would have been a very superior world chart.


The first three diagrams are taken from the Il Bulino CD of the charts held in the Biblioteca Estense for the 1525 planisphere as they are separately scanned in an excellent presentation. The text applied to each is taken from the 1529 planisphere thus giving the complete information required to be able to use the instruments. They are the Declination table, the Horary Quadrant and the Astrolabe.




The fourth diagram is an explanatory version of the Declination Table with the length of the months, dates and star signs appended.


The fifth diagram is a visual interpretation of the instructions given on the use of the Declination table. It clearly indicates that the northern section is nearly correct using the 187 days indicated but that the southern section is incorrect as it has only 178 days but is still a semi circle and equal thus to the 187 days.


The sixth diagram endeavours to correct this discrepancy of the days by using the 183/182 day hemispheres as per the MF de Enciso text and indicates that when drawn so the hemispheres both produce correct readings.


The seventh diagram is a visual interpretation of the distances indicated upon the Declination table for “off course” sailing to achieve one degree of latitude of 17 ½ leagues.


All of these indicate a very close adherence to the text by MF de Enciso and in all probability also indicate a close co-operation between Ribeiro and Enciso in Seville circa 1519/1523.

An interesting comparison can be made between the declination Tables produced by Guillame Brouscon from his “Manuel de Pilotage, a l’usage des Pilotes Bretons, dated to 1543. There are slight differences but the intervals of days are 187 and 178 as per the fifth diagram above. The use of the Months in Spanish is slightly off perhaps indicating the tendency of Ribeiro to think Portuguese. The table indicates the various names;

Enero Enero Enero Janeiro
Febiero Febrero Febrero Fevereiro
Marco Marzo Marco Marco
Abril Abril Abril Abril
Mayo Mayo Maio Maio
Junio Junio Ivlio Junho
Julio Julio Ivlio Julho
Agosto Agosto Agosto Agosto
Setiembre Septiembre Setiembre Setembro
Octubre Octubre Octvere Octubro
Noviembre Noviembre Noviembro Noviembro
Deziembre Diciembre Deziembre Dezembro


Having used the facsimile produced by Griggs through Chromo-Lithography I found it necessary to investigate its production.

His career commenced at the India Museum as a technical assistant and encouraged there he developed the process of Photo- Lithography. In 1868 he set up his own business at his home in Peckham, London producing facsimiles of, among other texts etc, the first edition Shakespearian Quartos and soon he was reproducing colour Chromo-Lithographic copies all based upon photographs.

Thus we come to the reason for the usage of the Facsimile copy of the Vatican 1529 Chart by Diego Ribeiro.

The copy held by Harvard College Library, USA, has the complete acknowledgement by W Griggs appended and reads as follows:

“Reproduced from the original in the Museum of the Propaganda in Rome, lent by His Holiness Pope Leo XIII, by W Griggs, London” and then “The Second Borgian Map by Diego Ribeiro, Seville, 1529”.

The information is as follows for the chart; “W Griggs c1887, facsimile, 1 map, 2 sheets; colour, 61 x 79cms and 61 x 66 cms, being 58 x 140 cms actual chart size. The original is 85 x 205 cms and thus the facsimile is two thirds actual size.

However the word “LENT” raised many questions in my mind which actually have yet to be answered as the Manuscript Department of the Vatican Library have so far failed to respond to my questions.

The chart had to be photographed and no doubt via a “Land camera” which had very large colour plates such that the negatives could be enlarged and photo engraved onto the stone slabs used in Chromo-Lithography.

However the date suggested for the facsimile is very suspect as the Leo XIII papacy only commenced 20th February 1878 and although early in his Papacy he re-established the Vatican Observatory it appears his move towards the 20th century was late in the 1890’s when firstly he became the first Pope to have his voice recorded and then c1896 he was filmed by a movie camera invented by W K Dickson who was Scottish on his Father’s side, he moved to the USA to work for T Edison but moved back to the UK in 1897 where he lived in outer London until his death in 1935.

Thus we have a possible link to the photographic part of producing the facsimile of the 1529 planisphere. Thus its date of production is more likely to be c1898, but where and how it was photographed is still unsolved. Somewhere there are stones plates with the negative image there-on, perhaps the Vatican required ownership, but until answers are given the story line must be curtailed for now.

The story of W Griggs and his workshop includes his house and workshop being destroyed by fire in 1883, the whole being rebuilt and the company existing for many years even after his death, run by one of his sons. Somewhere records probably exist and the search continues.


(There are five planispheres extant, all in the same hand and attributed by A Cortesao to Diogo Ribeiro. Two carry his name and three have the text appended to enable the instruments drawn there-on to be used. All but the 1525, Castiglione Chart is complete and have text appended regarding the geography.)
They were detailed in and reproduced by A Cortesao in volume one of his Monumenta.
1525, pp95-98, plate 37, Archivio Marchesi Castiglioni, Mantua. Diagram ChDR/1/D29
1527, pp99-101, plate 38, Thuringische Landesbibliothek, Weimar. Diagram ChDR/1/D30
1529, pp102-103, plate 39, Biblioteca Vaticana Rome. Diagram ChDR/1/D31
1529, pp 104-106, plate 40, Thuringische Landesbibliothek, Weimar. Diagram ChDR/1/D32
1532, pp 107-109, plate 41, (western part only including America,) Herzog August Bibliothek,Wolfenbuttel. Diagram ChDR/1/D33. (This chart is the subject of a book by E L Stevenson, titled, “Early Spanish Cartography of the New World- with special reference to the Wolfenbuttel-Spanish map and the work of Diego Ribero”.)
They are reproduced here-in from photographs taken of the Monumenta Pages for reference purposes as this text only discusses two of the five charts.






However ELS mentions on page 13 of his text the fact that the “Salviati” planisphere should be part of the overall pattern of charts in this period. I quote;

“The oldest Spanish maps of importance which have come down to us belong, to the third decade of the sixteenth century, and of these are no less than seven, all of considerable size. Arrange in what I take to be an accurate chronological order they may be designated as Turin-Spanish (34), the Salviati (35) the Mantuan (36) the Weimar-Spanish (37) the Weimar-Ribeiro (38) the Propoganda-Ribeiro (29) and the Wolfenbuttel-Spanish.”

His end note 35 reads, “a manuscript map of the world on parchment 209 x 98 cms in size and is preserved in the Laurentian Library of Florence, Italy. It is neither signed nor dated, but appears to have been drawn before 1526. Twice on the map the coat of arms of the Salviati appears.”


Cardinal Salviati is noted to have succeeded Cardinal Castiglioni in 1525, but when is not noted. The chart given to Castiglioni is dated 1525 and unfinished, hence the transfer may have been quite fast and the blank space upon the chart in fact may have been a space for the Castiglioni coat of arms. It is also possible that the 1525 chart was not even in a state to be given until the end of 1525 as it contains information from the voyage in 1525 by Estevam Gomez who made landfalls from Nova Scotia to the Florida coast and these are noted on the chart and dated to 1525.

But Diego Ribeiro was made cosmographer 10th July 1523 and the Salviati chart is certainly not in his hand. Preceding Ribeiro among others was Nuno Garcis de Toreno to whom the Salviati chart is tentatively ascribed, but considering the number of cartographers employed it could be anybody.. Therefore the dating of these is awry and as the Salviati Chart is obviously very close in design to the Castiglioni chart we must ask if in fact it is a 1523 chart, a plain chart as is the 1525 chart and repurposed as a later gift for Salviati during his 5 years as Papal Nuncio from 1525 to 1530. The chart is a Square Chart; the Mediterranean Sea is drawn as the 1525 chart, 45 degrees in length and the Line of demarcation is set at 30 degrees from the coast of Africa. The real difference is the numerous trees and the style of rivers drawn there-on. That it emanates from the Casa de la Contratation is undoubted and perhaps historians will shed light on the actual dating when the careers of the two cardinals are placed together.

Thus this text is in fact full of unanswered questions some of which will possibly never be answered but others I am hopeful of answering in the future.