

Royal Society. 467 



distance of five miles. Here the river is contracted to about a third 

 of a mile. Assouan is about 300 feet above Cairo, and the distance 

 between the two places being 556 miles, the average fall of the 

 river is little more than half a foot in a mile, 054, and Assouan 

 being 365 feet above the Mediterranean, and 696 miles distant from 

 it, the average fall of the Nile from the foot of the First Cataract to 

 the sea is - 525 in a mile. Low Nile at Cairo is 43 feet 6^ inches 

 (as measured by the French Brigade in 1847) above low- water mark 

 in the Mediterranean, and the distance being 149 miles, the average 

 fall is little more than 3^ inches in a mile. The author cites a re- 

 port of Mr. Rennie to the British Association in 1834, showing that 

 the fall of the Thames, between Chertsey and Teddington Lock, is 

 nearly 17y inches in a mile. 



The commencement of the annual inundation is about the sum- 

 mer solstice. The rise is scarcely perceptible for six or eight days, 

 it then becomes more rapid, and about the middle of August has 

 usually reached one-half of the greatest amount ; it attains its maxi- 

 mum towards the end of September, remains pretty stationary for 

 about fourteen days, and then begins to fall, at first at a more 

 rapid rate than that with which it rose, but after it has fallen one- 

 half the decrease is very gradual, and it goes on sinking until the 

 end of May. The rise continues about 90 days, the falling lasts 

 250. In 1846, Mougel Bey, the French engineer of the Barrage 

 near Cairo, found the maximum rise 7'20 metres, or 30 feet 10 

 inches. 



When the inundations commence, the Nile is of a. reddish colour, 

 and is loaded with sand and mud. From the fall between the Se- 

 cond Cataract at Wadi Haifa and the First, a distance of 214 miles, 

 being not more on an average than 9 inches in a mile, very little 

 coarse gravel can be transported by the river into Egypt. The 

 greater portion of the heavier detritus falls down in the higher parts 

 of Upper Egypt, and from the very gentle slope of the Delta, only a 

 small amount of the solid matter suspended in the water can reach 

 the sea; still, however, the sea has been observed to be turbid at a 

 distance of forty miles from the mouths of the Nile. 



The author then proceeds to describe the recent researches. His 

 first and indispensable step was to procure the aid of a competent 

 person to conduct his projected operations, and he was fortunate in 

 obtaining the active and intelligent aid of an Armenian gentleman, 

 educated and long resident in England, Hekekyan Bey, a civil engi- 

 neer, who had occupied some important positions in the service of 

 the Viceroy Mehemet Ali, especially as chief of the Polytechnic 

 School in Cairo. But nothing could be done without the consent 

 of the then Viceroy Abbas Pacha, more especially as the spot the 

 author had selected for his first operations was in a garden of the 

 Pacha. By the active intervention of Her Majesty's Consul- General 

 in Egypt, the Honourable Charles Augustus Murray, not only was 

 the Viceroy's consent obtained, but his Highness was pleased to 

 direct his ministers to place at the disposal of Hekekyan Bey what- 

 2H2 



