124 TRANSACTIONS OF THE [FEB. 24, 



into the Gulf of Suez, I noticed a prodigious bank of blown sand, 

 with a rounded summit and regular outline, estimated to be 200 

 feet high. The bank of sand called Seetzen^s Slope at Jebel 

 Nagous, rests on the hillside to the height of nearl}' 400 feet. 

 This I have described elsewhere (Trans. N.Y. Acad. Sci., IX., 

 21). The dunes immediately on the sea are comparatively 

 insignificant, eight to twelve feet high at the points reached on 

 my route. 



The phenomena of sonorous sand at Jebel Nagous, and my 

 discovery of a new locality (Ojrat Ramadan), have been fully 

 presented to the Academy. On my return to Egypt, I made a 

 careful examination of lofty and steep dunes near Ismailiya, 

 notes of which I take from my journal. 



On the southern borders of Lake Timsah (an adjunct of the 

 Suez Oanal), a series of dunes extends for more than three miles; 

 some of them rising to the height of 100 feet. At a point about 

 three miles from Ismailiya, between the lake and a shallow 

 lagoon separating it from the desert to the south, the north and 

 south winds meet in an eddy, blowing up the fine yellowish sand 

 in steep slopes terminating in a long knife-edge ridge. On the 

 steepest inclines the sand has the mobility observed at other 

 localities; there were signs of spontaneous movement down the 

 slope. I tested this sand at several places, two being a mile 

 apart; but all my efforts to coax sound out of the moving sand 

 were futile. The sand beneath the surface was not so dry as 

 that observed in the desert. 



The dunes are quite without structure ; the sand is uniform 

 in grain and color from the very edge of the lake up over the top 

 of the ridge. No shrubs or blades of grass find foothold on the 

 arid slope ; the surface is everywhere marked by wind-furrows 

 except where obliterated by the spontaneous sliding mentioned. 

 (Specimens.) 



The abrading and sculpturing by wind-driven sand may be 

 seen to great advantage in many places ; on the Nile, inscrip- 

 tions on granite temples and obelisks are sadly defaced where 

 exposed to this agent ; and in the desert most picturesque effects 

 are seen, especially in the sandstone region, as on the defile 

 called Nakb-el-Budra, and on Jebel Nagous. On the plains, 

 surface pebbles show a delicate pitting and furrowing caused by 

 the sand-blast. This is noticeable not only on soft gypsum and 

 limestone pebbles, but even on crystalline quartz. (Specimens.) 



Minerals. — Mineralogically the Peninsula is very poor. I 

 collected at different points snowy gypsum, fair selenite in im- 

 perfect crystals, and massive white chalk, and noted thin 

 streaks of epidote, small garnets, and quartz crystals. The tur- 

 quoise-mines of Maglutra, which were worked under the Pha- 



