explained in detail in earlier posts – search ‘Vesconte’; ‘Cresques’; ‘cartes marine’; ‘Angel of the Rose’; ‘Soler’, ‘Soller’ etc. etc.
 of an original four. see caption to detail illustrated (right),
 I have already provided bibliographic references for English translations of the essential texts.
Points about the circuit (as ‘compasso’)
- Within the Mediterranean, and until the 12thC (and still thereafter) Latins named the points by wind-names and combinations of wind-names. Present-day lists in secondary sources tend to adopt a standardised series but variants and differences in dialect and orthography were many. I recommend consulting primary sources and such scholarly studies as those by Patrick Gautier Dalché, Evelyn Edson, Barbara Obrist and Emilie Savage-Smith.
- Also within the Mediterranean, non-Latins (chiefly mariners) used a combination of wind- and star-names. This system is described as ‘Egyptian’ by Ibn Majid in the fifteenth century. I have already quoted the passage about these ‘Egyptian’ rhumbs’ from Tibbet’s translation of Ibn Majid’s work, and most recently as a ‘by-the-way’ end note to a post on the Lombardy Herbal. See (and if re-deploying the information please cite) D.N. O’Donovan, ‘The ‘beastly’ Lombardy Herbal Pt2′, voynichimagery. wordpress.com (July 22nd., 2013).
- Within the Mediterranean, the ‘rhumb-gridded’ cartes marine form their gridding ‘roses’ from topographic and geographic ‘trig’-points – not from simple imposition of the compass. On difficulties likely to be encountered by the researcher in this case, I’ll repeat the details of two articles brought to notice in earlier posts (e.g. here). Thomas E. Marston, ‘An aid to Medieval Portolan-chart making?’, The Yale University Library Gazette , Vol. 46, No. 4 (April 1972), pp. 244-246; E. P. Goldschmidt and G. R. Crone, ‘The Lesina Portolan Chart of the Caspian Sea’, The Geographical Journal , Vol. 103, No. 6 (Jun., 1944), pp. 272-278. Both Marston and Goldschmidt are linked to the history of the Voynich manuscript -one for his association with Yale University and the other as an expert in medieval manuscripts.
- In the Great Sea, points of the compass were named for stars. This is true from the Hawaiian islands to Oman and a number of the various forms of ‘star-compass’ system are documented. (see principally Ibn Majid’s Kitab al-Fawa’id fi Usul ‘Ilm al-Bahr wa ’l-Qawa’id and – for the older star-compasses – the University of Hawaii site). For the Chinese magnetic compass directions, see below. Information about non-Islamic India has proven difficult for the present writer to obtain. With regard to other evidence of the ‘square world’ – see Pt 2, following – Ibn Majid notes that the Gujeratis, like the Cholas of South India had their own ways of determining latitudes. Samira Sheikh, who appears not to have read Majid’s work and to have little appreciation of what sidereal navigation entailed, or why it was a lifetime’s study, asserts that “that the practice of observing the altitude of the Pole Star at its maximum elevation, as it crossed the meridian, was an Arab tradition adapted by seafarers on the west coast of India for latitude determination.” This is hardly so; we find the same practice known to seamen in most parts of the world, and certainly to medieval European mariners. During the fifteenth century, Nicolo de’ Conti lived for decades as a trader in India and southeast Asia, and yet did not seem to grasp the fact that it was not ignorance of the magnetic compass but disdain for it which saw the expert navigators refuse to have it or – if obliged to have one – refuse to use it. Sheikh quotes De’ Conti on Indian sailors’ “being unacquainted with use of the compass, but [they] measure their courses and the distances of places by the elevation and depression of the pole. They find out where they are by this mode of measurement”, again adding that once a vessel had reached the latitude of the destination port, it could ‘run down the latitude’ due east or west until the destination was reached. She makes the valid observation that this approach was particularly suited to long north-south coastlines such as those of India or East Africa, but in saying that “navigation was further aided by compass cards, that is, diagrams that combined directional information derived from constellations, the winds and the sun”, she misses the point. The card itself was no aid to navigation; the information about winds, stars, and other phenomena were maintained in the navigator’s inherited lore and constant study. Majid says himself that he had no need of a magnetic compass and the same is certainly attested to as late as the 1970s by scholars studying the traditional practice of Carolinian and Polynesian mariners. To ask such kanakas (as Majid also calls himself), to mechanically follow the dictates of such a mass-produced object was insulting – in much the way a chef might be insulted if told to serve nothing but regular, scientifically measured, microwaved hamburgers . But see: Samira Sheikh, ‘A Gujarati Map and Pilot Book of the Indian Ocean, c.1750’, Imago Mundi, Vol. 61, No. 1 (2009), pp. 67-83.
- The qibla system (also Romanised as Qiblah, Qibleh, Kiblah, Kıble or Kibla), named the points by places standing about the compass, though at variable distances, from a central point. David King has written important studies on the subject. I recommend particularly, D.A. King, ‘On the astronomical orientation of the Kaaba’ (with Gerald S. Hawkins), Journal for the History of Astronomy 13 (1982), pp. 102-109. A list of his publications can be accessed online.
- The Chinese had developed gridded maps by the time of the Han dynasty, and an order issued during the 3rdC AD informs us of a deliberate replacement, at that time, of an older meridian and latitude system with an imposed rectangular grid. I cite from the valuable paper by H.B Sarkar: “during the ministry of P’ai-Hsiu in A.D. 267 instructions were issued requiring that maps be correctly oriented and divided by a net, not of meridians and parallels, but of lines intersecting at equal intervals to form squares which were intended to facilitate the measurement of distance (in li) …” H.B. Sarkar, ‘A Cartographical Introduction to South-East Asia: the Indian Perspective’, Bijdragen tot de Taal-, Land- en Volkenkunde, Deel 138, 1ste Afl.,ANTHROPOLOGICA XXIV (1982), pp. 54-63. It was during the Sung dynasty (1000 CE) that in China “The [magnetic compass’] plate was converted to a bowl, and retained the markings of the heaven’s plate around its circumference, in a simplified form. The inner circle had the eight trigrams and the outer circle the 24 directions (based on azimuth points)”. Joseph Needham’s essay, included in the 1971 edition of E.G.R. Taylor, The Haven Finding Art, is essential for details here if one has no access to the more detailed treatment in Science and Civilization in China. Because the Chinese also held that the surface of the earth was square, (which belief they maintained to the eighteenth century, as I’ve already mentioned in this context), the most reasonable explanation for the form of the Voynich map’s ‘square world’ is influence from Asia upon more ancient matter, presumably retained east of the Bosphorous for most of its history. My chief reason for believing the map’s foundations are Hellenistic are the extraordinary detail in which the structure is drawn the west roundel and the nature and history of that figure which originally occupied the North roundel, but was so much later shifted to the its present position: North-west. On the ‘square world’ of the Chinese in relation to the Voynich map see, D.N. O’Donovan, ‘folio 86v The Square World’, published through voynichimagery.wordpress.com (3rd. September 2012) (here). I expect that few readers will have the opportunity to research the Chinese system, so I have quoted part of Batchelor’s article below.
What is known as the Selden map is a 17thC Chinese map now in the Bodleian Library (Oxford, Bodleian Library, MS Selden Supra 105). That map is illustrated (with inset compass drawn) in Robert Batchelor, ‘ The Selden Map Rediscovered: A Chinese Map of East Asian Shipping Routes, c.1619’, Imago Mundi (The International Journal for the History of Cartography), Volume 65, 2013 – Issue 1. That article can be read online.
In relation to its compass diagram, Batchelor writes, The compass rose is composed of an outer and an inner circle. Twenty-four rays, each marked with one of the twenty-four cardinal directions along with eight major compass directions, surround a small circle reading luojing (羅經, compass). Below the compass is a scale bar divided into ten sections, each marked with an ‘x’, and each subdivided into ten sections with a longer line for the half mark. The scale bar is perpendicular to the due south (牛, wu / 正南, zhengnan) line of the compass itself. Both appear to indicate a declination of approximately six degrees. Declination is notoriously difficult to determine in this period. …. Joseph Needham could only find two ‘Chinese’ measurements of declination in the early seventeenth century, both for Beijing, from Xu Guangxi (confusingly 5˚40′ʹ east) and Mei Wending scoffing at Adam Schall’s claim to have found over 7˚ of western declination by sundial measurement. [Batchelor adds bibliographic references]. .. The new calculations of A. Jackson, A.R.T. Jonkers and M. Walker, ‘Four centuries of geomagnetic secular variation from historical records’, Philosophical Transactions of the Royal Society of London, ser. A, 358 (2000): 957–90, suggest a figure closer to −5˚ on a line running west of Beijing down through Malacca on the western Malay Peninsula and across central Sumatra. View all notes This southward orientation corresponds to the famous ‘south pointing needle’ (指南針 zhi nan zhen) mentioned in texts from the Song Dyansty (960–1279) into the late Ming. See Zhang Xie, Dongxi yangkao (东西洋考; 1617–1618), 9:1; translated in Needham, Science and Civilisation in China (note 19), 4:1: 291–92. The two directional rays ding (丁) and bing (丙), one each on either side of due south, are extended in black-ink lines down to the scale bar.The small empty box seems to be, as Davies has suggested, a miniature version of the map itself, defining the declination of both compass and scale bar in relation to the basic frame of the map.
7. Ancient Greek zodiac ‘compass’ – theoretical. Jean Richer’s studies led him to conclude that there existed a system by which a given location was defined as the centre of a ‘compass’ about which other locations were identified by the circuit of zodiac constellations, as symbol or as image. Richter’s study still holds considerable interest, but his thesis is flawed by an assumption – inaccurate – that archaic and classical Greeks knew the same equal divisions and 12 constellations as those of the Roman zodiac, introduced to Roman dominions during the early centuries AD. The equal divisions were achieved by reducing the size of the Scorpion and making Scales of its claws, an idea unattested in the older Mediterranean. However, for general interest:
Jean Richer, Sacred Geography of the Ancient Greeks: Astrological Symbolism in Art, Architecture, and Landscape, (translated by Christine Rhone), SUNY series in Western Esoteric Traditions, (1994).
A somewhat unexpectedly impressive study of sacred directions was made by Nigel Pennick, in his Games of the Gods. Unhappily, his publisher did not see fit to produce the study with the academic apparatus it deserved, reducing its value for subsequent researchers since one cannot follow his information back to the primary sources. In those cases where the present reader had some prior knowledge of an item, the implied depth of reading for Pennick’s study was impressive..