The almost uninhabited country which connects Africa with Asia is flanked towards the south by two chains of hills which unite at right angles, and together form the so-called Gebel et-Tih.  This country is a tableland, gently inclined from south to north, bare, sombre, covered with flint-shingle, and siliceous rocks, and breaking out at frequent intervals into long low chalky hills, seamed with wadys, the largest of which—­that of El-Arish—­having drained all the others into itself, opens into the Mediterranean halfway between Pelusiam and Gaza.  Torrents of rain are not infrequent in winter and spring, but the small quantity of water which they furnish is quickly evaporated, and barely keeps alive the meagre vegetation in the bottom of the valleys.  Sometimes, after months of absolute drought, a tempest breaks over the more elevated parts of the desert.*

* In chap. viii. of the Account of the Survey, pp. 226- 228, Mr. Holland describes a sudden rainstorm or “sell” on December 3, 1867, which drowned thirty persons, destroyed droves of camels and asses, flocks of sheep and goats, and swept away, in the Wady Feiran, a thousand palm trees and a grove of tamarisks, two miles in length.  Towards 4.30 in the afternoon, a few drops of rain began to fall, but the storm did not break till 5 p.m.  At 5.15 it was at its height, and it was not over till 9.30.  The torrent, which at 8 p.m. was 10 feet deep, and was about 1000 feet in width, was, at 6 a.m. the next day, reduced to a small streamlet.

The wind rises suddenly in squall-like blasts; thick clouds, borne one knows not whence, are riven by lightning to the incessant accompaniment of thunder; it would seem as if the heavens had broken up and were crashing down upon the mountains.  In a few moments streams of muddy water rushing down the ravines, through the gulleys and along the slightest depressions, hurry to the low grounds, and meeting there in a foaming concourse, follow the fall of the land; a few minutes later, and the space between one hillside and the other is occupied by a deep river, flowing with terrible velocity and irresistible force.  At the end of eight or ten hours the air becomes clear, the wind falls, the rain ceases; the hastily formed river dwindles, and for lack of supply is exhausted; the inundation comes to an end almost as quickly as it began.  In a short time nothing remains of it but some shallow pools scattered in the hollows, or here and there small streamlets which rapidly dry up.  The flood, however, accelerated by its acquired velocity, continues to descend towards the sea.  The devastated flanks of the hills, their torn and corroded bases, the accumulated masses of shingle left by the eddies, the long lines of rocks and sand, mark its route and bear evidence everywhere of its power.  The inhabitants, taught by experience, avoid a sojourn in places where tempests have once occurred.  It is in vain that the sky is serene above them and the sun shines overhead; they