The Identification of the Lighthouse


The map of the ancient submerged blocks on the Qaitbay site was realised using a combination of methods: the primary topographical survey with the help of a tachymeter (an apparatus that measures vertical and horizontal angles and distances) and a system of buoys was combined underwater with the more standard methods (survey by triangulation, with the help of a metallic frame, and by photogrammetry).
The recourse to positioning by satellite or Global Positioning System (GPS), used particularly in the case of wrecks, resolved the problem of the points situated too far from the side. Finally the surveys and drawings of the chattels were carried out using polyester tracing (pencil and eraser) with the help of the draughtman's standard tools (rule, square, conformator, etc.)


The moving of the masonry blocks
through the use of balloons

It was necessary to move the very heavy blocks, sometimes weighing more than 70 tons, by using blown-up balloons. The information was then analysed and classified in computer files so as to establish the cartography of the site. These data served as a basis for the reconstitution of the Pharos monument in 3D.


Map of the Masonry Blocks

The delegation under Jean-Yves Empereur is convinced that they have found the first components of the lighthouse at Alexandria. They have itemised a dozen specific masonry blocks that are part of a monumental edifice which collapsed east of the island of Pharos. The impressive size of these Aswan granite blocks (more than 11 metres in height and 50 to 70 tons in weight) that only the Egyptians knew how to sculpt, together with their underwater position exactly opposite the Qaitbay Fort indicates that they are part of the Pharos of Alexandria. These components could be pieces from door and window frames

The French delegation's conclusion also relies on several ancient accounts and more recently on those of geographers, of Greek, Arab or French travellers or engineers who even then described the position of the lighthouse as being on this very site. These include the geographer Strabo, who passed through Alexandria in 25 BC, the traveller Abd el-Latif el Bagdadi, who visited Alexandria in 1200-1201 AD), or the French engineer G. Jondet.

Excavation : Jean-Yves Empereur, CEA ; Diagram, Map : CEA ; photo : Stéphane Compoint © Corbis Sygma, Authorised Reproduction Only