809

Monalosphaerium; Cosmotheoriae & de Proportionibus J F Fernel, Measurements; Accuracy & Fantasy Abound

J F Fernel wrote three texts which indicate his first studies, mathematics and astronomy. Here-in they are evaluated, but only “Monalospharium” and “Cosmotheoriae” are completely investigated, whilst “de Proportionibus” is simply explained. Thus the measurements involved, the length of a degree of latitude and basic geometry, which includes Euclidian methods are all discussed. It is obvious that J F Fernel is using the work of Claudius Ptolemy, he notes the Almagest text, but his greatest usage is of “Geographike Hyphegesis” when he discusses latitude and longitude, although somewhat at variance.
However all three texts as published are full of errors; the figures are awry and the calculations leave a lot to be desired with a lack of explanation of their basic components.
It is obvious from the construction of the three books that they were compiled between c1520 and 1525 thus allowing publication in 1526 and 1528. The errors are twofold being both original and printer/publisher as the errata do not cover the most obvious. Thus it is clear that the three books were written from notes taken over the 5 years, transcribed at a later date and thus errors were made. However the idea and work involved in measuring the land surface to determine the degree of latitude cannot be criticised; it is a pity as will be shown that a modicum of inaccuracy crept into the methodology and J F Fernel was swayed by spurious measurement comparisons. Some never actually existed and are mathematical enigmas. Basically all three texts require to be carefully read before accepted as correct.
The text is 17 A4 pages and contains 15 A4 diagrams.

June 2017
Read Paper  View Diagrams  Download Paper  Download Images 
812 1393

MARINUS OF TYRE AND THE 500 STADES HOW MUCH LATITUDE FOR A DEGREE OF LATITUDE

All latitudinal measures can only be determined on the face of the Earth and thus any given measurement can be assessed as to its place of origin, because the earth is an oblate spheroid, a fact not known in antiquity, and thus has variable latitudinal lengths. But when the measurements used are variable but by having the same name can be completely misinterpreted, any attempt to ascertain its actuality whilst not doomed to failure can end up being mathematical, “playing with numbers”. Thus a strict evaluation of the parameters, both the form of the Earth and the base length, the Stadion, must be made to avoid the criticism of numerical fantasies. This text attempts that with regard to the latitudinal degree known as 500 stades, exploring all facets of its possible origination from ancient times.
I have appended my text ChMEA/1; Charts their latitudinal measures re-assessed from historical attempts to define the degree of latitude as it preceded this new text and is in fact therefore a text which should be read in conjunction with this text CgSTA/1.

The text is 7+7, A4 pages and contains 6, A4 diagrams..

November 2016
Read Paper  View Diagrams  Download Paper  Download Images 
1403 2982

THE ARAB COMPASS IS NOT A COMPASS BUT A CHART;
TWO CHARTS DRAWN IN NORTH AFRICA? 1413-14 AL-TANJI AND c1350 MAGHREB CHART

The text “Using a Portolan at Sea, did they?” indicates quite clearly the nonsense of considering that at any time a magnetic compass was used for either route sailing or the construction of a Portolan Chart. The latest paper available, “The Maghrib’s Medieval Mariners and Sea Maps; The Muqaddimah Primary Source”, explains precisely what a “Compass” is, and it is not magnetic. Then in this text, having followed the development of Portolan Charts from their Genoese foundations in Italy, and after via Majorca and onto Egypt these two charts, one drawn in Tunis, the other certainly Arabic, but unknown are investigated. The Tunis chart is a standard Portolan, but the Maghreb chart is probably an atlas page and these are to be examined apropos the Genoese and Majorcan continuity of chart design. The indication is that the setting out of the wind rose graticule is a perfect copy of the Petrus Vesconte 1318 Atlas page which illustrates the methodology of how to draw the graticule sans circle, and these charts are typically the follow on product of Genoese charts.

THE TEXT IS 10, A4 PAGES AND CONTAINS 22, A4 (A3) DIAGRAMS

August 2019
Read Paper  View Diagrams  Download Paper  Download Images 
3010

ChAR1 Images

ChAR/1/D01 ChAR/1/D02 ChAR/1/D03 ChAR/1/D04 ChAR/1/D05 ChAR/1/D06 ChAR/1/D07 ChAR/1/D08 ChAR/1/D09 ChAR/1/D10 ChAR/1/D11 ChAR/1/D12 ChAR/1/D13 ChAR/1/D14 ChAR/1/D15 ChAR/1/D16 ChAR/1/D17 ChAR/1/D18 ChAR/1/D19 ChAR/1/D20 ChAR/1/D21 ChAR/1/D22

Read Paper  View Diagrams  Download Paper  Download Images