CLIMATE OF EGYPT. 831 



transversely or obliquely to the normal ranges. The bottom of the trough between 

 two parallel ridges presents a tolerably good footing to the wayfarer ; but progress 

 is extremely difficult on the slopes of the crumbling sandhills. No springs rise 

 at the foot of the dunes ; no living thing dwells in this region of death, where 

 travellers themselves plodding wearily and silently through the sands seem like 

 phantoms to each other. 



Climate of Egypt. 



The climate of Egypt, although very different in the neighbourhood of the 

 Mediterranean and in the narrow valley of the Upper Nile skirted on both sides 

 by the escarpments of the desert plateaux, is remarkable especially for the 

 uniformity of its phenomena, the regular course of the atmospheric currents, and 

 the dryness of its atmosphere. In its meteorological conditions, the valley of the 

 Nile, that is to say, Egypt, resembles the Red Sea. As in all mountain gorges, 

 the aerial currents which penetrate into this marine basin follow it regularly in the 

 direction of its length. Here they become changed either into the shemal, or wind 

 of the Gulf of Suez, or else into the assiab, or wind of the Gulf of Aden. Thus 

 the north-east monsoon, which in the Indian Ocean prevails from October to 

 March, changes its direction on entering the Gulf of Aden, where it becomes a 

 south-east wind. So also the khamsin, which comes from the Libyan desert — that 

 is, from the west — on reaching the Red Sea is deflected northwards parallel with 

 both coasts. In the same way the western, northern, and north-eastern currents 

 from the Mediterranean, all alike take a direction contrary to that of the south- 

 east monsoon. On the other hand, the land and sea breezes, which alternate with 

 such remarkable regularity on most of the tropical coast lands, play a very feeble 

 part along the shores of the Red Sea. Utilised to a limited extent by sailing 

 vessels for a few hours of the day, they are borne now to the north, now to the 

 south in the general current of the atmosphere. They acquire a little influence 

 only at the change of seasons in spring and autumn. 



Under the action of the alternating northern and southern breezes, a correspond- 

 ing movement takes place in the Suez Canal, where in summer the Mediterranean 

 waters are driven towards the Red Sea, in winter, those of the Gulf of Suez 

 towards the Bay of Pelusium. About 14,000,000,000 cubic feet of water thus ebb 

 and flow from season to season, at a velocity varying from 6 to 26 inches per 

 second. In the Nile Valley, as in the long trough of the Red Sea, all the winds, 

 whatever their original direction, change in the same way to currents setting north 

 and south. In Lower Egypt alone, where no obstacle intervenes to obstruct their 

 course, they blow from all quarters of the compass, according to their original 

 direction and modifying local influences. 



The alternation of the aerial currents is regulated in the Nile Valley with less 

 uniformity than in the Red Sea. In this longitudinal basin they succeed each 

 other in almost rhythmical order. In winter the south-east monsoon, which rushes 

 impetuously into the Strait of Bab-el-Mandeb, acquires the ascendancy, and makes 

 itself felt at times as far as the neiohbourhood of Suez. In summer, on the 



