Cataracts of Upper Egypt, from the Description de l'Égypte Carte topographique.
The maps of Egypt prepared by the French engineers and surveyors in Napoleon’s expedition were exceptionally detailed, as shown in this section of Upper Egypt that includes the famous sites of Philae, Syene, and Elephantine. The completed map was so superior that the military convinced Napoleon to seal it as a state secret, keeping it unpublished for many years after the rest of the Description de l'Égypte was completed.
|Detail of the Pyramid Meridian, from the Description de l'Égypte Carte topographique.
The French cartographers used coordinates on their maps of Egypt that were based on a longitudinal meridian passing through the tip of the Great Pyramid of Giza and a latitude line at right angles to it. Everything could be plotted from the intersection of these lines, which was an acknowledgement of the precision of the north-south alignment of the Great Pyramid. Its four sides are almost perfectly aligned with the four cardinal points of the compass.