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Several authors have endeavoured to produce a plausible lifeline story for B Crescenzio, but the only definitive result, because He states it is that he was employed in the Naval Ships of Pope Sixtus V and Pope Clement VIII. From these texts the only specific dates are between 1587 and 1602, with the possibility he entered marine service in 1570, serving on the Galee’s of that squadron.

His first and extant text is entitled “Proteo Militare di Bartolomeo Romano, Divisio in tre libre”, and Osvaldo Baldacci states, “L’attivita marina del Crescenzio, avrebbe avuto inizio nel 1587; infatti, del “Proteo Militare”, apprendiamo che il 5 luglio del 1587, il Crescenzio era nell’isola di Scarpanto”. It was published in Naples, 1595.

But in 1596 he constructed a “Portolan Chart” of the Mediterranean Sea basin, which he states “corrects previous errors” and for the publication of “Nautica Mediterranea” produced a plain chart copy to be engraved and is bound into the text as will be discussed later.

In fact, Pope Sixtus V (1585-1592) inaugurated the “Permanent Squadron” to counter the Turkish Pirates. We can trace the places he visited from his second text, “Nautica Mediterranea di Bartolomeo Crescenzio Romano”, published in Rome in 1602. Thus we know he sailed (among other voyages) from Civitavecchia to Naples; between the islands of the Archipelago of Argentiara to Milos, was in Avignon as well as the Ionian and Aegean Seas. But in 1595 he was in Messina, the cartographic centre which at that time was the base for the OLIVES FAMILY of cartographers whose Portolan Charts are so well known today. It appears he was in Civitavecchia, 1596, at the behest of the Pope to restore the port, but his 1596 Portolan Chart is dated “Rome, Kal Jan anno MDXCVI. Bartolom”

He carried out Hydraulic Studies for Ferrara, Ravenna and Bologna in 1605 and is noted as such in a document dated 1607. The publishing dates are therefore the most plausible to use as finite, but the dates for the charts being produced may vary.
There now follows the investigation of the two texts and two charts in the order of FIRST TEXT; PROTEO MILITARE DI BARTOLOMEO ROMANO; (Six original text pages)

For a reason he does not explain, Bartolomeo Crescenzio has designed an instrument he describes as capable of aiding many forms of architectural and topographic measurements. He states “Nel primo si descrive la fabrica di ditto Proteo & in esso nuovo istrumento, tutti gli altri istrumenti, di Matrematica che imadinar si possano” and “ditto Istrumento, nelquale si formano tutte le figure di Geometria & gl’Istrumenti di Prospettina, Pittura, Scoltura e d’Architectura”.

Three diagrams; ChBC/1/D01, D02 and D03, (1,2 &3)
It is a three bladed construct which opens like a pair of compasses and he illustrates the text with numerous diagrams indicating the possibilities of its usage. It is dedicated to “Fra Emilio Pucci, Commendator Gierosolimitano. Generale delle Galee dis Nostre Signore” and the text contain some surprises such as the diagram which purports to illustrate how “Alberto Duro” (Albrecht Durer) could have used “It” to produce his perspective drawings. It is thus rather fanciful and along with the other examples he gives does not inspire usage which is possibly why it did not become a “Must Have” instrument in the 17th century.





It is a standard Portolan Chart of the Mediterranean Sea basin and is dedicated as follows;
Ill. Mo ac Rev. mo D. no Cardinali Pietroi Aldobrandino D. no Osservantissimo. Quantis et quails maximus Ill. Me Praesul erroribus scateat marina carta, qua nautae utuntur, neminem tam cosmograporum quam Nauclerorum latet; idque in locorum latitudine necnon in ventorum veris vijs agnoscunt. Neque aliunde hoc provenit nisi quam maris nautae astronomica instrumena occident talibus familiarsisima quibus littoral et situs Siderum terrae tractus locant prorsus ignorant. Sed ne tanti erriris caligine mortals dictitarent libenter hanc cepimus provinciam. Et iam septem lapsis annis noticon po nos cartam felicis recordationis Comendatoris Fr, Emilij Pucci iussu a peritissimis Cosmographis et Naucleris ex aminatam perfecimus ac D. no tibi meo sicut voluisti mittimus. Accipe ergo, Princeps parvum munusculum et sicut Auctoris illius etiam protectionem habere dignare. Vale. Romae, Kal. Jan. anno MDXCVI Bartholom.


The chart is drawn on a single vellum skin with the neck to the west, the foregoing inscription plus two examples of the heraldic emblem of Cardinal Aldobrandino below it.

The chart has a latitudinal scale on its western bordure from 23N to 53N and using the normal scale bars appended each latitude is 84 sbu’s. But there is also a chequered subdivision of each latitudinal degree with 6 parts and this could indicate 60 Miglia Marittima, 6 x 15 miliaria= 90 per degree or 6 x 100 stades given that the latitudinal degree is also 75 Roman Miles, each of 8 stades. There are 4 scale bars, each identical in measurement and each subdivision has four dots giving five subdivisions of 10 units. From the foregoing it is open to all to opine the actuality, which is made harder when the charts measurements of distances is analysed. Clearly there is a major problem with the latitudes as denoted because the 36N Mediterranean Sea latitude is ½ degree awry as then are the latitudes 35N to 45N. This could be the result of a simple draughting error, but study the 31N latitude and that is correctly aligned in a horizontal west/east form. But, 31N to 36N are 75 sbu’s and 36N to 43N are also 75 sbu’s conflicting with the actual latitudinal scale, but also indicating the standard Portolan Chart latitudes for the Iberian Peninsula as Roman Miles per degree.

However, if the diagram is studied, then instead of a “standard portolan” with the slewing of the latitudes in an anti clockwise direction caused by the mis-measurement of first Iberia and then the Levante, we see a clockwise slewing, that is towards the south up to the 9E longitude. From there this chart takes on a similar construct to most Portolan Charts and at the 36E longitude the latitudes are stretched to 100sbu’s between 31N and 36N, then from 35N to 36N we have 75 units and from 36N to 45N it is 89 sbu’s, giving an overall 31N to 45N as 91 ½ sbu’s or if considered Miliaria a nearly correct degree of 90 units. But of course it could also mean that the possible degree lengths are a mixture of the units from 75 RM to 90 Miliaria.

ChBC/1/D05A/B (5&6)

In the central area of the western Mediterranean Sea, Sardinia and Corsica, there is a problem of size positioning. (ChBC/1/D05A/B)(5&6) In simple terms from South Sardinia to Cape Corse it is 39N to 43N as indicated in BLUE, but they have been drawn south of the correct latitudes and Sardinia is well oversized latitudinally. Their position is not helped by the fact that the west coast of Italy, coloured BLUE is protruding far into the Tyrrhenian Sea. The dotted lines indicate the direct alignments of the Toe and Heel to Genoa and Venice with the eastern coast of Italy being the most accurate. By drawing Italy slightly mis-shaped, Corsica and Sardinia could not be correctly positioned latitudinally even ignoring the oversized Sardinia. By indicating a putative position for Genoa the longitudes from 6W, Cape Spartel, are 70 sbu’s, but it then exposes the residual mis-positioning of the centre of the chart. However a total overall from 6W to 42E (Black Sea) is 70 sbu’s per degree of longitude, which is close to the required 72 sbu’s for a 90 Miliaria degree of latitude.

The 1596 chart certainly corrects one error that of the slewing of the latitudes from 6W to 18E, by actually slewing the latitudes southwards but then introduces so many other errors as to negate that enormous leap by possibly recognizing that latitudes all traverse west/east and are parallel and should be drawn as such. However, having produced a Table with a complete set of longitudinal degree measurements from 1 to 90, (based upon a 60MM degree of latitude for easy mathematics) he has completely ignored them and produced a standard rectangular graticule chart, based on an unknown latitudinal measure. For 36N, the Latitude/longitude Table produced on page 163 has 36-48-32 (i.e. at 36N the longitude is 48 miglia 32’ which is calculated by 60x Cos 36 = 48.541 or 48 miglia 32.46’ and thus a very accurate 48.541MM per degree. However it should be noted the chart latitudinal measurement is 84sbu’s which would give 67.957 and at 90 Miliaria it is 72.81, but as the Roman Mile has been used we must include 36N as 60.676RM per degree of Longitude.

ChBC/1/D06A/B (7&8)

The second example of the 1596 chart (ChBC/1/D06A/B)(7&8) has a simplified latitudinal layout, where-on the actuality of the deformation southwards can be readily seen. When those latitudes are drawn strictly to geographical readings instead of as the first chart example it indicates an endeavour to understand if the latitudinal scale could be used as there is a large discrepancy which increases as the lines progress west.

ChBC/1/D07 (9)

The third example (ChBC/1/D07)(9) is to indicate that the actual and putative latitudes do not align and has all the latitudes from 35N to 45N plotted in RED with the corresponding latitude scale projected in GREEN.

Thus I can opine that as with the Francesco Beccari chart, where-on he writes that he will correct the faults of previous Portolan Charts, and fails miserably (text ChFB/1), this supposed correction of errors by Bartolomeo Crescenzio likewise fails.


In the heading text for Nautica Mediterranea, B Crescenzio writes; “Si manifesta l’error delle carte Mediterranee, e degli Astrolabii, e Balestriglie, e da dove essi errori procedono, dando poi la vera Charta, et altro piu giusto e facile Astrolabio e Balestriglia con una Bussola ch’in nessum meridian gregheggi o maestreggi.” Diagrams ChBC/1/D08; D09; D10 & D11(10-13)

The frontispiece explained its content in five paragraphs as is illustrated. They are basically concerned with the construction of a Galee, the correction of errors in Mediterranean Charts, the Art of Navigation, Nautical calendars, Moon, solar etc., as well as a long diatribe regarding the calendar change-Julian to Gregorian and the loss of 11 days and the Epact. Finally, the fabrication of armaments and a chart plus 63 pages of Portolano end it.

ChBC/1/D08 (10)

ChBC/1/D09 (11)

The design of the frontispiece is both nautical, mystical and historical, with three cartouche. The upper contains the arms of Cardinal Aldobrandino which has a tessellated diagonal with six stars. But those situate left and right are very different indeed.

ChBC/1/D10 (12)

ChBC/1/D11 (13)

THE LEFT HAND CARTOUCHE has in its centre a prancing horse set onto a crescent moon and the outer oval curves have between them the double inscription; φίλοϛ ίππώυ IN DIES CRESCIT. (THE LOVER OF HORSES-HE GROWS DAY BY DAY).

This refers to the text ; “Marcus Junianus Justinus; Epitoma Historinin Philippiques- Pompeus Trogus” Book 41, which is headed; “The Parthians down to Mithridates 1” and subheadings for the first two chapters, 1) origin and growth of the power of the Parthians and 2) Their manners, mode of fighting and religion.

Chapter 2 has the following section; “Exercitum non, ut alies gentes, liberorum sed maiorem partem servitiorum habent, quorum uulgus nulli monumittendi potestate permissa ac per hoc amrubus servis nascentibus IN DIE CRESCIT. Hos pari ac liberos suos cura et equitae et sagittare magna industria docent”.

“They have an army, not like other nations, of freemen but chiefly consisting of slaves, the numbers of whom daily increase, the power of manumission being allowed to none, and all their offspring, in consequence being born slaves. These bondsman they bring up carefully as their own children and teach them with great pains, the arts of riding and shooting with the bow”.

But why this should feature within a nautical treatise by an Italian in the service of the Pope is unfathomable, unless he was trying to show how erudite he was and knew the Parthian Army defeated Rome.

THE RIGHT HAND CARTOUCHE. Again in an oval frame with a centre being a drawing of a bridge with five keys over. The Inscription reads; AQUIFLAVIENSES- D.S.F.C.

At first I thought this was a reference to an aqueduct system supplying water to Rome, but an eminent scholar pointed out that AQUAE FLAVIAE was in fact the modern city of CHAVES in northern Portugal. Hence the cartouche is actually the armorial bearing of Chaves with the Trojan Bridge and its 5 keys denoting the definition of Chaves, Keys, and it is the access point from northern Spain into Portugal, the key to the region.

But the letters DSFC, if a classical text would be D(E). S(UO IMPENSO ). F(ACIENDUM. C(URAVENT). That is, “they took responsibility for the making at their own expense”. This is no doubt reference to the fact that Trajan a Flavian Emperor built the bridge at Chaves from his own resources.

Again though, what Bartolomeo Crescenzio was actually referring to is unfathomable now if that is not the solution. The Galee at the bottom of the page complete with oars, a shaped prow and carved face to the stern by the steering oar echo’s the upper page Galee with double lion heads and forecastles. This may also be a reference to the NNW wind rose. But, the initials B_A may stand for anyone or anything.

The text commences with a letter dated 5/12/1601 to “Dottore Nicolo Ghiberto di Loreno, gia Medico delle Galee di Nostro Signore: Amico Lettore: Bartholomeo Crescenzio, Ingegniero Pontificio, Sanita Perpetua”. Within this letter he mentions Vitruvius and there is the only mention outside of “Proteo Militare” of the instrument.

A simple précis of the books contents now follows;

BOOK ONE; he mentions historical figures concerned with mathematics and philosophy; Socratae- Herone Alessandrio- Platone- Archimede- Leonte dEudosso- Aristotle. Then adds, Se Noe, Deucalione o Dedalo: Lidijo Epaminonda fatera gli inventori de Navigli, and finally he mentions Marc Antonio and Ottaviano. He discusses the Galee its materials and construction, hull shape and even the design of the anchor. There are also curious instruments drawn which do not appear to be recorded again.

BOOK TWO- Del numero & ordini de Venti, in che e diviso LÓrbe dell’Aqua & Terra, redotti in Planisferio overo Carta da Navigare. He states the “Equinotty cioe 21 di Marzo & 24 di Settembre”, then mentions Vitruvius again and his winds (page 157). Next he talks of TOLOMEO (Claudius Ptolemy) and the 90 degrees latitude with a table of the “Parallels” and their individual lengths based upon an equatorial degree of 60 miles.

He then has the following two sentences: Pietro Nonio (Nunes) nel suo libro de arte Navigandi confessa lérrore manc pero L’accommoda. Agostino Cesareo, in un’altro suo trattuto di Navigatione, fa una nota de gradi dell’altezza polare diciasuno de luoghi principali del mare Mediterraneo & mar Negro.

He mentions a Nicolo Sagri and again Ptolomeo and the latitude of Allessandria in gradi 31. We then read; “Tolomeo, Martino & gli antichi vogliano che ogni grado contenga Miglia 60 di passi geometrici, da cinque piedi l’uno——— una cosmografia modern ache nota gli errori del Sacrobosco, assegnaa ciascum grado Miglia 62 e mezzo. Il Medina, come sopra si disce Miglia 70 in iuna cart ache noi habbiamo hauuto da un’Inglese Piloto di Francesco Drach, che contiene dallo stretto di Gibiliterra fino all Olsatia con l’Isolo d’Inghiltera & Irlanda nella quale si metiono a gradi dell altezza Polare & la scala dell Miglia contiene ogni grado Miglia 100.”

Comment; this indicates the complete idiocy of the medieval period in believing all Miglia were the same! However, the mention of Francis Drake is quite strange.

Then we read;” Alessandro Piccolomini atterm che Miglia 87 e mezzo sequendo la sperienz a di Eratostene Cireneo”
COMMENT; this is the completely idiotic assumption of Jaume Ferrer when he read the newly translated text of STRABO which there-in describes the degree of Eratosthenes of Cyrene being 700 stades. But of course 90 miliaria of 8 stades per unit gives 720 stades total and thus has to be reduced by 20 stades or 2 ½ miliaria. However, 90 Miliaria is actually 75 Roman Miles and thus 600 stades so the calculation fails completely. (text ChJFF/1)

If we study page 163 and pages 207/208 then the mathematics of the age and of Bartolomeo Crescenzio become available to us. The table on page 163 is headed;

“Tavola che cotiene il numero delle Miglia ch’ad ogni grado di ciascun Levante ponente Parallelo, al levante pon. De gl’Equinottij, si permette”. Diagram ChBC/1/D12(14)

This table is based upon a latitudinal degree of 60Miglia, as already stated. Thus it immediately becomes a simple mathematical translation multiplying the Cosine of the Latitude by 60 and then removing the “Miglia” and leaving the decimal remainder to be again multiplied by 60 so that the resultant figures are Miglia and Minutes.

Diagram ChBC/1/D12(14)

It is a decimal calculation, not fractional because from Muslim Spain, trignometrical tables spread to Latin Europe. Then Regiomontanus (Johannes Muller von Konisberg, 1436/1476), a German Astronomer and Mathematician composed the first tables with decimal values. Similarly Joachim Rheticus (1514/1574), a student of Nicholas Copernicus, prepared a set of tables of all six trignometrical functions at 10” intervals, accurate to 10 decimal places. Rheticus also took the decisive step of defining trignometrical functions in terms of Angles rather than arcs and as ratios rather than lengths. The French mathematician Francois Viete published his tables of all six Trig. Functions in “Canon Mathamaticus (1579) in which he calculated the functions at 1’ increments and accurate to 5 decimal places.

Hence Bartolomeo Crescenzio who we are told was a competent mathematician among other attributes could prepare a very accurate set of Longitudinal degree measurements base upon 60 Miglia, but in doing so of course chose the easiest of Miglia to work with, when the base figure was actually 90 Miliaria.

Diagram ChBC/1/D13(15)

On page 207, Libro Secondo, (diagram ChBC/1/D13)(15) there is a curious discussion and diagram regarding the length of a degree of longitude at 23N, when the latitudinal degree is 60 miglia, and we have already seen the calculation. It appears a rather eccentric method of finding the hypotenuse of a square whose side length is derived from the projection of the 23 degree line both north of west and west of north founded on a square with the circular quadrant encapsulated as the diagram illustrates. From the table 23N has a longitude of 55 14/60 which should be capable of producing or generating a hypotenuse in that when the circle diameter is known. Tan 23 will produce a length on the opposite side to the angle which is the side of the square and if this multiplied by √2, the hypotenuse is known.

Diagram ChBC/1/D14(16)

But Crescenzio has developed a mysterious square which has 8 segments per quadrant all differing lengths as they are generated from the half wind angle of 5.625 degrees up to 45 degrees. The diagram ChBC/1/D14(16) sets out the measurement generated and when it is completed the quadrant side is copied with its ever enlarging sub-divisions and laid along the 45 degree hypotenuse and the required number is obtained, 55 14/60ths; BUT WHY?
Tan 23 = opposite over 180 and therefore Tan 23 x 180 = Opposite or the squares side. The 180 is the circle.
Tan 23 = 0.4244748 x180 =76.405. Simple but not the figure given which is 55 14/60, the correct distance from a degree of longitude at 23N based on 60 Miglia.

Bartolomeo Crescenzio has given a tabulated form which uses the Cosine correctly to obtain Latitude/longitude. Thus the raison d’être for this diagram which even an excellent draughtsperson will find very hard to execute at such a small scale accurately enough to be read from ( hence my larger diagram version) when the simple explanation of Cosine Mathematics would ensure a quick and accurate distance measure was obtained from the tables available. Like many of his grandiose ideas they are rather overblown to use.

Curiously on page 185 it has the question “Qui va la carta da Navigare”, and on page 186 describes a chart of Ireland! The book then continues to describe various instruments but on page 259 is the design of a special Bussalo-Compass.


This discusses a variety of information including Rivers and the Nile Crocodiles; the Strait of Magaglianes with a small chart; The Tides; Sailing in the Irish Sea and the ports of Ireland and then it discusses the EPATTE, the reform of the calendar, 11 lost days and the Moon cycles and Sun Declination.


Predicated upon the year 1595 it has tables of Declination, Sunrise & Sunset and then Portuguese tables of Declination are included.


Discusses fighting the Corsairs and Turcs with a single comment “molto piu Navi di Corsari Inglesi” and perhaps the reason for the left side Cartouche on the frontispiece, he writes, “Supero Pompeo gli squadron di Mitridate”, and follows it with “l’anno 1571 l’armarta Christiana abate et fracusso quella de Turchi”.

Finally he discusses weapons and fighting strategy at sea with also the reconstruction of land based defences.

Next is the table of contents in which he does not mention the Proteo Militare he has designed.


However, inserted just prior to this heading for the Portolano text of 63 pages is a copy of the 1596 chart specially drawn at the same scale as the original, although on a smaller sheet, it is an exact copy. It was therefore folded into the book and the chart clearly shows that fact.

THE COPY CHART ANALYSED Diagrams ChBC/1/D15; D16A/B and D17 A/B(17-20)

If the original 1596 chart was devoid of colour and produced on two sheets as per this black and white version they would be indistinguishable from each other apropos the actual coastlines. The overlay diagram clearly proves this point. This chart however does have many features which distinguishes it from the former in the subsidiary parts.

Firstly, in a small cartouche in the SW corner there is a very different text, as follows;

“Chartam Mediterraneam antea magna obrutuam falsitate quam pro priis expansis post longam septem annorum navgationem, summamque diligentiam in investigandis locorum gradibus et veris ventorum viis, non sine nmanifesto libertatis ac vitae periculo, ab solvimus: posteaque coram Ill. Mo Commendatore Pucci classis Pontificiae Generali duce, a praeclaris simo nauta Fratre Vinceguerra equite Hyerosolymita no examinatam, approbatam ac valde commendatam iam, ab antquis erroribus purgatam, in lucem, et nunc manu propria desciptam mittimus; ut in nostril saeculi gloriam, ad navigantium utiitatem, in posteros transeat; acipe ergo allam generosa Italia (et si tibi magnae atque uberrimae virtutum parvum munusculum) sicut et alias elucubrationes nostras libenter accepisti. I terim sub Clementissimo Pontifice feliciter vive et in aeternum tua maneat felicitas.

Romae anno virginis Partu 1596; Inventor Prothei”.

ChBC/1/D15 (17)

The translation is as follows;

“The chart of the Mediterranean, previously greatly ruined by falsehood, which we repaired at our own expense after a long navigation of seven years and the greatest care in investigating the degrees (of latitude) of the places and the true paths of the winds, not without clear danger to liberty and life; and afterwards, it having been examined , approved and strongly commended by the most famous sailor Brother Vinceguerra, Knight of Jerusalem, in the presence of the most illustrious Commendatore Pucci, commander general of the Papal Fleet, now rid of ancient mistakes we send it into the light now drawn by our own hand; so that the glorification of our age it may pass on to posterity for the benefit of sailors; therefore accept this other (chart), O noble Italy (although a small gift to you being such great and abundant virtue), just as you have accepted our other works of toil; meanwhile under the most “clement pontiff” live happily and may happiness remain with you forever; At Rome in the year of the Virgin’s parturition 1596. The discoverer of the Prothei.

Other than the most expansive hyperbole imaginable he has a sense of humour as the Pope was then Clement VIII.

ChBC/1/D16 (18)

In the NW and SW corners are copies of the frontispiece oval cartouche, which start and complete the latitudinal scale. But the most surprising features of this chart are the eight wind rose circles which hold drawings of animal and within the outer rims a descriptive text.

They are as follows;
NNE; A Reindeer; Retrogradiens Pasciter Alces Sarmatiae Campus
ENE; An Elephant; Hic Afrique Quondam Limites Notabut Deserto (? In the Black Sea)
ESE; A Rhinocerus; Indus Praeter Hunc Non Vidit Unicornium Unovam
SSE; A Nile Crocodile; Ad Vada Nili Occisor Occibum Plangit Amade
SSW; A Camel: Obediens Genu Mauro Inservit Camellus
WSW; A Lion; Colit Pardus Ferox Deserta Libae Nemora
WNW; An Oxen; Hinc Hercules Punt In Latum Hesperides Boves
NNW; A Winged Lion; Bartol. Crescentius Insignia Venetus Diuum Dedere Beati
Thus he cleverly ensures his name is on the chart just in case nobody realises he is the “Inventor Prothei”. But as he styles himself ROMANO perhaps there is another reason.

The overlay chart of 1601 is in Green on the Portolan Chart of 1596 and includes the latitudinal scale bars clearly indicating they should be considered one and the same chart apropos their coastlines.

ChBC/1/D17A/B (19&20)


Published in 1602AD at Rome it is a sectional Portolano with curious omissions from the overall text in its sub-sections.
Section 1; Genoa to Spain (Gibraltar and Cadiz)
Section 2; Genoa to Naples
Section 3; Naples “fino al Capo di Santa Maria.”
Section 4; Partenza da Capo Spartelli che rest sopra la testa dello Stretto di Gibilterra dalla parte di Barbaria verso Mezodi.
Section 5; Nota di tutte le Isole & stanza dallo Stretto di Gibiltera fino al capo di Spartivento
Section 6; Partenza di Venetia verso Levante
Section 7; Per andar da Capo Malio S Angelo a Constantinopoli con Galee, a terra a terra

The following investigation is not a place to place construct as written but an overall view of the major distances scattered throughout the text. Unlike “Lo Conpasso Da Navigare” it is not divided into two sections, “Starea and Peleio”, thus there is no organised set of distances or organised coastal sailing place to place, and in fact there are swathes of coastline omitted.

Firstly however to completely illustrate the text sections, Section 1, the Genoa to Spain coastline is discussed. Then the last section, 7, to Constantinopoli is investigated as it is a very curious text and route.

Prior to the distances being investigated it is necessary to reiterate the possible measurements that may have been used as there is an obvious confusion. The basic original measurement was the Roman Mile of 8 stades and a degree of latitude was 75 Roman Miles or 600 stades. From this two other measures evolved and are used on the majority of Portolan Charts, the Miliaria of 6.667 stades and the Miglia Marittimo of 10 stades. They have a simple relationship and are all latitudinally 600 stades per degree because there are 90 Miliaria and 60 MM per degree.

Then there are the spurious Miglia such as that proposed by Jaume Ferrer and also by J F Fernel in his Latin texts. Simply put J Ferrer read the translated text of Strabo and there-in the works of Eratosthenes of Cyrene where he stated a degree of Latitude was 700 Stades. But 90 Miliaria calculated wrongly of course is 720 Stades and thus J Ferrer reduced the Miliaria by 20 Stades to 87 ½ miliaria. Nothing in his works are thus correct. There is also the ARAB Degree measurement of 56 2/3rds Miles as chosen by Alfraganus from four measurements made to determine the DEGREE, two on the Plain of Srinjar, and all using the Black Cubit at 4000 to an Arab Mile. The measurements are, 56, 56.25, 56.667 and 57 Arab miles and of course Alfraganus chose the wrong one as it should be 56 Arab Miles.

My texts describing all of the above measurements are as follows:
ChMIL/1; Portolan Charts; Distance measures; No more vague assumptions
ChMEA/1; Charts and their measures assessed from historical attempts to define the degree
ChMES/1; Jorge de Aguiar 1492 and Pedro Reinel 1584. Myth of the League derivation
MsFER/1; Jaime Ferrer1495 and J F Fernel 1528, problematic surveys
MsJFF; J F Fernel Measurements Accuracy and fantasy abound
ChMM/1; The Miliaria as a measurement; Whence came the Miliaria of the Medieval Age

Thus when the distances quoted by Bartolomeo Crescenzio are tested against the Geographical Kilometrage, the conversion can be established. But, the question must be asked; where did Crescenzio obtain his DATA? Is it all his own work, doubtful, and thus if he is using a variety of texts has he ascertained the given distances are the same MIGLIA?

SECTION 1, GENOA TO SPAIN (pages 1-10 of NM)

The route explained is generally coastal sailing interspersed with some Peleio distances, but one glaring omission exists, the coast from Cap Colonne close to Marseilles to Cap di Creo (Cape Creuz), basically the whole coast of the Gulf of Lyon until Port Vendres and Collioure.

PAGE 1; Genova—all’isole d’eres in Provenza si correla Costa Greco & Libeccio che sono Miglia 200.

Leaving Genoa sailing Greco in fact would take you 36 Km off course after the 250KM , that is 203 miliaria. Thus at around 44N latitude or Cape Mele the course should alter to Greco ¼ Tramontana and the distance would be correct.

That confirms for this section the Miglia is in fact the Miliaria of 1.2326KM.

PAGE 3; “Partendo dall bocche di Rubaldino con il Capo Creo, si guarda alla quarta dell Libeccio verso Ponente, che si guarda con la quarta Greco verso
Levante & vi sono Miglia 200 & con detta corsa fe van el golfo de Roses. Dette Bocche con il ditto capo, guarda fra Ponente & Libeccio fra Greco Levante & vi sono Miglia 170”.

Firstly the route is actually Rubaldino /Creo, ¼ Ponente verso Libeccio and is 240KM or 200 Miliaria, and as the Gulf of Roses is actually south of Capo Creo it cannot be 170 Miglia but 207 Miliaria and virtually the same course.

“Le Pomeghi di Marsiglia con Capo di Creo si guardano Greco Libeccio & vi sono Miglia 140 in circa”, and also, “Capo delle Colonne con Capo di Creo si guarda ¼ di Libeccio verso Mezogiorno & con la ¼ di Greco verso Tramontana vi sono Miglia 140”

The first is 195KM or 158 Miliaria and the second 180KM or 146 Miliaria but both winds for the journey are acceptable although the first should be ¼ Greco verso Tramontana and the second Greco. Thus I suspect that Crescenzio is copying or mis-copying a previous text or notes.

PAGE 4; “Tigne—– dette con il Capo di Creo, Mezogiorno Libeccio and Greco Tramontana sono Miglia cento dieci”. This is 170Km from Martigues to Cape
Creuz or 138 Miliaria, but also 92 Miglia Marittimo thus the error is either 18 or 28 Miliaria.

SECTION 7; Per andar da Capo Malio S Angelo, a Constantinopoli con Galee a terra a terra.

The description of the route is quite curious in that it is very tortuous around Negroponte/Eubea and could easily be described by a much shorter voyage. But, bearing in mind the problems with the Turkish Fleet and Corsairs, keeping close to land rather than a slightly longer open sea voyage via Skyros (Schiro) (97 miglia) from the strait Negroponte/Andros may be the reason, but unlikely as the Crescenzio route then has what would be the same long open sea voyages (65 and 97 miglia respectively) to Tenedos.

But more alarming are the distances quoted which are awry as well as the wind directions. Commencing at Capo Malio, S Martino, 12 miglia, then Malvastia 18M. The first is unknown but Monemvasia is Malvastia and at 30m acceptable. Next we read Valle si S POLO, 6m and Botte 6m. The description of Botte fits the port of Limani Geraka, where you sail northwards past a large point and then reverse course to enter the small bay of the port. It is actually 17m not the 12 quoted. From Botte to Sette Pozzi (SPETZES) is c60m not the quoted 15m, but the port of Spetzes is on the north of the island. Crescenzio gives no direction but it is Tramontana, but next he quotes “Da Sette Pozzi navigando per Maestro a Miglia trenta, andare a Napoli di Romania”, that is Nafplio and it is 50m with the direction Maestro up the gulf.

The following sentence is “ Da Sette Pozzi volendo andare a Negroponte naviga per Greco tramontana & poi per tramontana & vederai l’Isole, che sono nel Golfo di Settines sopra Coranto & li fara la Sidra che e buona Isola & bon porto di verso Ponente & Maestro”

Crescenzio describes the direction including Tramontana when it would be far better described as Levante and then Levante ¼ Greco, which will facilitate passing Sidra (YDRA) and its port direct to Le Colonne ( Cape Sounion) by passing Isola S Giorgio d’Albora which has no port which is described in the next two passages of his text. However there are the usual distance problems throughout this section. Thus from this point in the investigation we find that from Botte the distances are awry if we consider them as Miliaria, Re-work them as Miglia Marittimo and the distances quoted are acceptable. But why would Crescenzio alter the distance measure from 1 to 11/2 miliaria for his Miglia unless he has not realised that perhaps what he is copying has changed measurement.

The route Le Colonne via Macronisio (Makronisas) to the Isalnd of Zia (KEA) to the east, levante is then described, but, sailing north from Le Colonne along the eastern coast of Akri Apollona, Crescenzio uses the waterway, Canal, between that mainland coast and the island of Negroponte (EUBEA) and quotes 60 miglia from Valle e la Macina (RAFINA) to the “CITTA” (Chalkida) and that would also be correct for the Miglia Marittimo of 1.8489KM. At the Citta di Negroponto there is a bridge, “La prima punta”; then it is S Giovani and the Mount Spartivento (Kandili). The route is then described as following the waterway but in no real specific terms because it requires sailing north then west, then north around the cape and then Greco is used to sail past the northern coast of Negroponte and the “Golfo del Fiteleo” and “Loveo” and finally sailing eastwards past the islands of Scariello (Skiathos), Copeli (Skopelos), Andrini (Alonniso) and Chinocci. Now it is Greco passing Kyra Panagia (Mine Pelegi), Lamia, Arfura, Le Sandole and Schiro che e da Scirocco in mare. The crossing to Stalimene ( Ag.Efstratio) is actually Greco not Tramontana as written and is 90KM, that is 73 Miliaria or 49MM and certainly not the 20 miglia quoted. However, Tenedos is “greco” but without a distance measure given.

The last section, entry to the Dardanelles and out into the Sea of Marmara is straight forward enough to the Island of Marmara, but then the route and instructions stop. We then read a diatribe concerning the “La Vittoriosa Armarta Christaina” which refers to the sack of Constantinople in 1204AD by the armada sailing from Venice. The text discusses what are basically the exploits of the 4th Crusade and the release of Hungary and the “Armata Pontificia”, which is no doubt the reason for its inclusion.

Bartolomeo Crescenzio never reaches Constantinople!

*Diagrams ChBC/1/D18; D19 and D20 (21-23)
The basis of these diagrams is to indicate the coastlines that Crescenzio mentions, but more importantly those He chooses to omit, although the coast of Turkey is possibly understandable as He could not visit it, but the N Coast of Africa had trading ports.

SHEET 1; Diagram ChBC/1/D18 (21)

A composite diagram deals with the Mediterranean Sea between Corsica/Sardinia to Gibraltar, with routes not previously described in the foregoing text. They are scattered amongst Section 1 and Section 5 of the text. The accuracy as already indicated varies as do the wind directions given. If text ChLCN/1 is studied then coastal sailing wind directions can be seen to be based upon just that fact, following the coastline except where necessary to cross a bay or open water. B Crescenzio does not appear to have taken heed of the simplicity of this method of sailing and the errors are perhaps a sign he is using some of his own notes but also previously written texts, combining them with catastrophic results of distances.

SHEET 2; Diagram ChBC/1/D19 (22)

This sheet illustrates the Adriatic Sea and the fact that Crescenzio chooses to coastal sail through what he calls CANALS, that is the journey between Islands along the east or Dalmatian Coast. However, He completely ignores the western coast or East coast of Italy from Venice to Cape St Maria. No opinion can be given as to why.

ChBC/1/D18 (21)

ChBC/1/D19&D20 (22&23)

SHEET 3; Diagram ChBC/1/D20 (23)

The main section of the sheet indicates the curious route He chooses from Cape Malio to Marmara and the southern Dodecanese islands noted. The inset map indicates the curious journey from Cape St Malio to Cyprus and the Levante coastline. He uses Castel Rosso an ancient fortification island sails east for a few miles and then heads for Cyprus. He skirts the south coast and leaves at the NE Cape to sail to Beirut and then south wards down the coast to Ashkelon. Here he just states return to Beirut and sail northwards and then returns to the NE Cape of Cyprus. This coastline is obviously previously known from the Crusades and as with the diatribe concerning Constantinople and the 4th Crusade it is quite likely this coastline information comes from the same ancient text.

COMMENT; thus the Portolano heading “in tutor il mare Mediterraneo, con le sue traversie, & luoghi pericoli” is very far from correct. The obvious use of a number of distance measures would make it very hard for any navigator to use without prior knowledge.


In January 2021 a rather overlong and somewhat out of date text was posted online. I freely admit I did not actually read every word, basically scanning through it to extract data and reading some sections in an endeavour to find a raison d’être for the text because its abstract flies in the face of numerous scholars research.

The Abstract; “Circumstantial evidence places the Portolan Chart in an unidentified west coast Italian port between 1154 & 1204. No mathematical calculations or measurements were involved. In essence the Portolan Chart was not a geographic or cartographic construct but a memorial experience transposed into a geometrically consistent graphic form, with coastal outlines and toponyms added afterwards, Instead of enquiring whether Greek or Romans had marine charts, we should rather ask, did they produce graphic versions of the charts they apparently held in their heads, to which the answer is that there is no evidence of that.”


The text I am referring to should be read with extreme caution as it can be shown to be written from non updated data much of which appears to stem from the 1980’s. Thus it does not reflect the researches carried out by numerous persons which clearly indicate that the basic premise of the text is wrong. That the Greeks and Romans particularly had maps is well illustrated, but even from The History of Cartography chapters 9 to 14 of volume one it is quite well explained. However the text written by R K Sherk, ”Roman Geographical Exploration and Military maps” and the work of Professor OAW Dilke in subsequent papers clearly illustrate that maps were abundant. But why call a map specifically a “Marine Chart” when a map of the Mediterranean Sea basin such as the simple Michelin map is as much a marine chart as a Portolan Chart with all the coastal ports named.

Do not forget that the so called Wind Lines or Rhumb lines spread over these maps are quite useless as an aid to sailing, because they are predicated upon Geographical NSEW that is the proper winds, when the maps are slewed up to 12 degrees anti-clockwise. Couple that fact with varying latitudinal measurements across the map which serve only to distort it, thus any plotted courses are wildly inaccurate and the winds totally awry.

The listings of ports did not suddenly appear for the first extant chart, the so called “Carta Pisana”, it took years to compile and follows the “Roman Itinerary” system, land and sea listings of routes and distances, and was certainly not compiled between 1154 and 1204.

I draw your attention to the following sample information;
Tiberius Sempronius Gracchus won victories on Sardinia and after celebrating a triumph set up a tablet (“Tabula”) in the Temple of Mater Matuta which included a map (“FORMA”) of the island. (Livy 41.28, 174BCE)

In 54BCE a Roman (known) world Survey was carried out and Marcus Agrippa had the map painted on the walls of the Forum in Rome (See RmSU/1). Also in my text is the information that Aristogoras of Miletus visited Cleomedes of Sparta and produced a map of the Aegean, Turkey and Mesopotamia. (Herodotus Book 5, 43-56)

King Roger II of Sicily (A Norman) had a large fleet and did not take part in the Crusades but required to know therefore where his enemies were located and commissioned a chart from Al Idrisi 1139/1154AD, such that he had the information and the Admiral of his fleet knew where he could raid. It is a typical Arab map, but the text written by Al Idrisi contains many distance measures and sailing data. The map comprises of 70 tableaus which form the complete Mediterranean Sea from the Atlantic to the Black Sea. (text CgId/1 to /4)

Thus I suggest before stating the Greeks and Romans did not have marine charts or as they should be actually called maps, a little historical research would be appropriate. Just because in the 20th century we try to distinguish between the two, it is only a given name. Proper marine charts are a league away from the Portolans, which are merely copies of copies covered in so many lines that they inevitably required greater payment.

I also suggest that any person who does not agree actually reads my text – Ch12/1; Portolan Charts and Their Standard Distortion; Whence came the Portolan Chart?; Roman, Yes! This text sets down the complete argument for a Roman Original from a person who is not a Roman Enthusiast, but just tells it as the evidence dictates.


A curious assertion is made within that text in end note 141, where it clearly states that “correction of the Mediterranean tilt can be seen on a chart by Diogo Ribeiro (1525)————- and a Portolan chart by Bartolomeo Crescenzio (1596)”. I beg to differ having just researched the latter and written about the former in my text ChDR/1.

ChBC/1/D21 (24)

Study the diagram of Diogo Riberio (ChBC/1/D21)(24) which is in fact a square chart having latitudes and longitudes equal and it is so very apparent that in fact instead of an anti-clockwise tilt or slew he has produced a clockwise slew and mis-positioned the latitudes in the east by an increasing amount as the proceed northwards, a typical Portolan error.

This is not a correction of the tilt/slew as it is indicated upon an enlarged longitudinal measurement of 25% along the 36N latitude and hence if drawn “geographically”, that is latitudes 90 miliaria and longitudes 72 miliaria the tilt/slew would be increased clockwise and hence any apparent reversal of the anti-clockwise tilt/slew has merely been reversed. It does not correct anything!

Now study the diagram of the 1596 Bartolomeo Crescenzio Portolan Chart (ChBC/1/D07)(9) and it is of a similar form, There is a tilt/slew of 40 clockwise which if the Latitude/longitude was drawn 90/72 instead of 84/72 the tilt /slew would be greater in a clockwise direction and the eastern Mediterranean even more anti-clockwise than drawn. Again no correction is apparent.

ChBC/1/D07 (9)

Both charts have the 31N latitude drawn there-on, but the Diogo Riberio chart is wildly inaccurate whilst the Bartolomeo Crescenzio chart has it correctly drawn indicating the Gulf of Lesser Surt and Alexandria at 31N. Having made a major statement about “Alessandria” being at 31N in his text, we should perhaps expect nothing else.

Thus considering these two charts as a “correction of the Mediterranean Sea tilt/slew” is a fallacious statement and should be removed.


Bartolomeo Crescenzio being an Engineer has chosen to produce many ideas and instruments which he believes may be applicable to sailing the Galee’s of the Pontifical Squadron. They are overly complicated and thus the reason that they do not appear in the future. The second text, again tries to discuss the construction of a Galee and its mathematical beginnings for the hull etc. It is incomplete and probably of little help. Then the Portolano is again incomplete with large tracts of the coastlines missing and diatribes filling the void. It is also in-accurate and likely to lead to problems when the varieties of distance measures are taken account of. With the number of dedications he uses so prominent in the texts, it can only be that he is over stretching himself by intending to assist and please all concerned.

Bartolomeo Crescenzio is obviously an educated person, an engineer a mathematician and scholar who has unfortunately not achieved his potential through the publication of his texts and Portolan Chart.