120 TRANSACTIONS OF THE [fEB. 24^ 



sometimes of coralline limestone, intermingled with flint and 

 other varieties of amorphous quartz. Many of the pebbles show 

 on their surface beautifully regular pittings and furrows carved 

 out by the wind-driven sand. (Specimens shown.) The fine- 

 grained sand has all been lifted high in air by the powerful 

 winds, whirled away and dropped into depressions or on the lee 

 sides of hills. Hundreds of acres have no surface stones larger 

 than an ostrich-egg ; no water whatever is found in this region, 

 much less any signs of vegetable or animal life, rarely even a 

 passing bird. 



On this desolate plain, when overtaken by night, one place 

 is as good (or bad) as another for pitching the tents, unless 

 perhaps a small hillock is reached which may serve as a partial 

 shelter from the gales that sometimes threaten to overturn the 

 canvas. 



Wadis. — In the region of extensive plains, the wadis, or dried- 

 up water-courses, being depressed but little, closely resemble 

 them. The floor of the wadi hardly differs from that of the 

 plain, except when a torrent has swept before it large boulders 

 and deposited them irregularly in its bed. The sorting power 

 of the water, however, is noticeable, as also the well-defined 

 vertical walls, perhaps only a few inches deep, excavatea at the 

 point of lowest level. On the margins, too, of the wadis of the 

 plain, and at points protected from the full force of the winter 

 floods, several varieties of green shrubs grow in widely separated 

 tufts. I often remarked mud-cracks, apparently of recentdate; 

 but these indications of water probably remain undisturbed in 

 this desolate region for a considerable period, perhaps for several 

 seasons. 



In the limestone hills these wadis take the form of cauons, 

 having nearly vertical walls, sometimes hundreds of feet high, 

 — as in Wadi Tayyibeh. The regular erosion on their sides 

 produces often picturesque effects, as at Kas Abu Zanimeh. 



In the granitic district the wadis form V-shaped valleys 

 broken by narrower ones entering at right angles, and bounded 

 by bold peaks many thousand feet above the beholder. In the 

 beds of these wadis are scattered specimens of the rocks of the 

 surrounding country; often boulders of great size testify to the 

 violence of the torrents during the winter months, especially in 

 Wadi Feiran. (Specimens exhibited.) 



Water. — The absolute dependence of the population of Egypt 

 upon the Nile is a familiar fact, discussed from the time of Hero- 

 dotus to the present day. The proposed re-opening of Lake Maoris 

 in the Fayoum district, for irrigating the Delta, has been fully 

 explained to the Academy by one of our members, Mr. F. Coi)e 

 Whitehouse, its enthusiastic advocate. 



