112 
MR. HORNER ON THE ALLUVIAL LAND OF EGYPT. 
was formed in 1846, under the patronage of the Viceroy of Egypt, Mehemet Alt, for 
the express purpose of making a careful survey of the isthmus, in order to determine 
the question of the level of the two seas. The association consisted of Messieurs 
Talabot and Bourdaloue on the part of the French, Mr. Robert Stephenson on the 
part of the English, M. Negretti on the part of the Austrians, and M. Linant de 
Bellefonds (Linant Bey) on the part of the Pacha. Mr. Stephenson undertook to 
observe the levels of the tides at Suez, M. Negretti those at Tineh on the Mediter- 
ranean, near the ancient Pelusium, and the survey of the land was undertaken by 
M. Talabot and M. Bourdaloue with several assistants. A report of their operations, 
accompanied by maps on a large scale, and detailed tables, was printed at Nismes in 
1847, under the title of “ Society d’Etudes de ITsthme de Suez, Travaux de la Brigade 
Franqaise, Rapport de ITngenieur,” but has not been published*. The results 
obtained were as follows : — 
That the low-water mark of ordinary tides in the two seas, at Suez and at Tineh, 
is very nearly on the same level, the difference being, that at Suez it is three centi- 
metres lower, that is, rather more than 1 inch ; 
That the mean rise of ordinary tides in the Red Sea is somewhat higher than in 
the Mediterranean, but that the maximum difference is not more than 80 centimetres, 
or 31^ inches ; 
That the rise of the equinoctial spring tides at Suez over the low-water mark in 
the Mediterranean at Tineh at the same period is 2’38 metres, or 7 feet 9 inches; and 
That the deepest low-water mark at the same period at Suez is 0*45 metre, or 
17'7 inches under the deepest low-water mark at Tineh. 
The highest point of the isthmus between Pelusium and Suez is 12 74 metres, or 
41 feet above the Mediterranean, the distance between the two places being 12f 
myriametres, or about 78 English miles. 
The north-westernly prolongation of the Libyan range of hills, which form the 
western boundary of Upper Egypt, is composed of the same nummulite limestone, 
covered by the upper sandstone. The sandy desert at the foot of the range, like 
that on the eastern or Arabian side, contains pebbles of agate and flint, and masses 
of fossil wood, stems of which have been found 40 feet in length changed into 
hornstone. Parallel to the direction of the Libyan hills, and on their eastern side, 
are two depressions of great extent, one of which there is every reason to consider as 
a former channel of the Nile, and goes by the name of the Valley of the Waterless 
River ; the other is the Valley of the Natron Lakes. 
Lower Egypt, geologically considered, is formed of the low and almost level land 
included between the Mediterranean and the hilly regions which form what may be 
termed the natural boundary of Upper Egypt. The central portion formed by the 
divergence of the Nile about sixteen miles below Cairo, into two branches that fall 
into the sea at Rosetta and Damietta, constitutes the present Delta. The distance 
* I have had it in my possession through the kindness of Mr. Robert Stephenson. 
