Indirect evidence suggests that charts and chartmaking were familiar to Ottoman mariners in the late 15th and early 16th centuries. The corpus of known material suggests a great deal of interaction between the marine traditions of Islamic and Christian states bordering on the Mediterranean (J.B. Harley and David Woodward (eds.), The History of Cartography, Vol. II, Chicago, 1992, p 263). The present chart is sophisticatedly drawn and in fact more sensitive than many 17th century Western European sea charts. No Ottoman Turkish portolans or navigational charts are known to have existed earlier than AH 906/1500 AD. The earliest examples of Islamic marine mapping are four charts from the Maghreb indicating that chartmaking centres existed in North Africa before they did in the Ottoman capital of Istanbul.
The difference between the practical portolan and those intended explicitly for presentation and decorated with elaborate ornamentation is best illustrated by the existence of two versions of Piri Re'is' (ca. 1470-1554) original Kitab- Bahriye ('Book of Maritime', dated 1521 and 1526), the second of which was designed to impress Sultan Suleyman and was heavily embellished (Harley and Woodward (eds.), op. cit., figs 14.11 and 14.13, p. 276). Piri Re'is' celebrated map of 1513, (now in the Topkapi, R.1633 mük) is similarly decorated with fantastic inland and nautical decoration including ships and mythical beasts making it a significant artistic feat as well as scientific document (Esin Atil, The Age of Sultan Süleyman the Magnificent, (exhibition catalogue), New York, 1988, no. 35, p. 79). The large format of the present chart may suggest a purpose as an unfinished decorative wall chart.
The lack of multiple compass roses or rhumb lines, which one would expect of a serious cartographic document, seems to eliminate the notion that this was envisaged simply as a navigational tool. Furthermore the Mediterranean sea in the present chart has been tilted clockwise so as to fit onto two large square composite sheets of paper, rendering the longitude lines at a gentle angle and the intention of accurate navigation unlikely. These lines may even be a copying tool or a form of projection. Whilst this prevents us from seeing the map purely as a navigational device, parallels are found elsewhere. In an article entitled 'Islamic Charting in the Mediterranean', Svat Soucek writes that it was not unusual for Ottoman cartographers to adjust the orientation of a coastline to fit the surface available and cites for example the mid-16th century chart of Hajj Abu al-Hasan in the Topkapi where the coastline of southern Africa is distorted to fit the vellum (H.1822, in Harley and Woodward (eds.), op. cit., fig.14.4, p. 267).
A plausible explanation, proposed by Professor Beatrice Gruendler of Yale University, is that this map would have been used by an Ottoman Admiral for naval warfare. She mentions that the detailed and accurate marking of many costal locations other than just port cities are important for possible landing sites and sheltering ships. Rather than as a map designed simply for navigation, this was perhaps conceived as a tool for plotting campaigns. The marking of castles with perspective plans along the coast lines further supports this argument.
Professor Gruendler notes that Kâtib Celebi, (1609-1657) an Ottoman scholar whose most famous work was the Kashf al-zunun 'an asami al-kutub wa al-funun, is said to have commented that the production of 'blank' maps was undertaken by 15 workmen in 8 shops in Istanbul in the 17th century. It is also known that a number of copies of Re'is' Kitab-I Bahriyye were produced as simple contour maps without toponyms which were then filled in by sea captains. Soucek also suggests that as with the 'Ali Macar Re'is' atlas (Topkapi Saray Müzesi, H.644, dated AH 975/1567 AD), it is quite possible that mariners, technically unequipped to make such charts themselves would acquire blank ones bearing only costal outlines which they would then complete or amend with appropriate toponymy (Harley and Woodward (eds.), op. cit., p. 283). Without money or motive to acquire refined illuminated specimens it is probable that those 'blank' portolans or charts produced were similar to the present, and it is very possible that it fits into that group.
RGruendler notes that the presence of satellite towns such as New Tripoli and New Alexandria that are not depicted on Piri Re'is's celebrated 1526 map suggests a date of the late 16th or early 17th century - between the reigns of Sultan Murad III (d. 1595) and Murad IV (d. 1640). This is confirmed by analysis of the paper on which the map is drawn. The paper is of a type made using wire moulds, a technique first introduced into the Ottoman world towards the end of the 16th century and was used in the first half of the 17th century. Probably imported from Italy, though possibly from Iran, this paper replaced earlier types which were manufactured on grass moulds. Thus the 'laid lines' which are clearly visible on the surface are straight and regularly spaced, numbering approximately 15 to the centimetre. By the mid 17th century paper typically shows an obvious sheen and glaze due to the increased quantity of size used on its surface. The paper used for this map has less gloss than were it from the latter half of the 17th century.
We would like to thank Professor Beatrice Gruendler for her advice in preparing this note.