116 TRANSACTIONS OF THE [FEB. 24:,. 



crossing the pliiin, we entered a defile and rose to a considerable 

 height on the Nakb-el-Budra ; the sand-storm continued, quite 

 spoiling our enjoyment of the wild scenery and making photog- 

 raphy impossible. In the evening the fierce wind very nearly 

 overturned our tents in spite of extra stays, and at dinner every 

 course was seasoned with the all-penetrating dust. The tem- 

 perature at 7 P.M. was abnormally high, 84° ; just twenty-four 

 hours later it had fallen to 58°, the wind having meanwhile 

 veered around to the north, bringing with it heavy mists. 



The manner in which sand is driven up the slope of Jebel 

 Nagous by the wind from the Gulf, I have described elsewhere 

 (Trans. N. Y. Acad. Sci., IX., 21). 



A single instance of electrical display was observed on March 

 26th, while in camp at Sinai. My companion, Henry A. Sim, 

 Esq., of the Madras Civil Service, while lying in the tent, drew 

 bright sparks from the woollen blankets by friction ; the tem- 

 perature without was about 64°. 



Before dismissing the subject of climate, I wish to testify to 

 the invigorating, delightful air in the desert; it has a bracing 

 quality that enables one to expend much energy without fatigue. 

 From about 1 to 3 p.m. the glare of the sun is often great, and 

 shade is a comfort ; but the constant breeze, sometimes rather 

 too strong, tempers the heat. I suspect, too, that the air is very 

 free from disease-germs. 



Of the dreaded Khamsin, however, I can say nothing favor- 

 able. 



Physical Geograj^hy . —^Qmn\^mg you that this is a record of 

 experiences and impressions, and not an essay on meteorology, 

 geology, etc., I shall not repeat familiar descriptions of the 

 wonderful Nile valley ; the views shown in connection with this 

 will illustrate certain features. 



I made several excursions in the neighborhood of Cairo ; on 

 the west lies the river, and across the bridges cultivated fields so 

 far as irrigated ; beyond that the Libyan desert. On the east 

 the quick transition from the streets of a city, swarming' with 

 400,000 inhabitants, to the sterile desert, is very striking; 

 passing through an arched gateway, and by some sorry-looking 

 Mohammedan burying-places, one immediately finds himself on 

 gravelly, undulating plains, devoid of water and foliage, extend- 

 ing in monotonous uniformity to the Gulf of Suez, about 80 

 miles distant. Jebel Mokattam, a limestone range on the south, 

 rises nearly 500 feet above the city ; my aneroid gave the 

 elevation of the highest point overlooking Cairo as 694 feet 

 above the sea-level, or 485 feet above Shepiieaid's Hotel. The 

 desert, broken occasionally by low ranges of hills, has a hard 

 gravel and pebble floor, chiefly limestone with fragments of 



