1890.] XEW YORK ACADEMY OF SCIENCES. 115 



and filling the orifices in his head with a very fine dry dust. 

 Khamsin is from an Arabic word meaning fifty, so called from 

 a mistaken notion that it blows for a period of fifty days before 

 the summer solstice. 



In the Nile valley, north winds prevail during the heated 

 period of eight months, and southern winds during the rest of 

 the year ; these being in the opposite direction from the winds 

 in the region of the Red Sea. 



Sand-storms. — I witnessed three characteristic sand-storms at 

 localities far apart and under varied circumstances. On Feb- 

 ruary loth, when riding a donkey through Thebes Nileward, a 

 powerful west wind arose in the afternoon, blowing before it 

 fine dust from the Libyan desert. Words fail to describe the 

 discomfort of such a sand-storm ; the fine dust seems able to 

 penetrate everything except perhaps an unbroken egg, and it is 

 quite impossible to escape from it; to prevent suffocation, I 

 borrowed from a fellah a coarse yet closely-woven blue outer 

 garment and wrajiped my head up. Donkeys did not seem to 

 enjoy the phenomenon any better than the Bedouins, and they 

 shrunk from its blast as well as the travellers. On reaching the 

 river, we alighted, but found the waves so high that boats could 

 not cross to take us over, and we had to wait in patience until 

 the force of the wind was spent. I tried lying down on the 

 shelving shore, but the coarser grains of sand driven near the 

 surface cut into the skin with painful effects. After crossing 

 to Luxor in a boat, we found the residents in the large hotel 

 much inconvenienced by the penetrating dust, although the 

 building is screened by a handsome garden. 



My second experience was in Cairo itself. On March 6tli a 

 northwest, and consequently a cool, wind blew dust from the 

 adjoining desert into the city with such power as to obscure the 

 usually brilliant sun during an entire day. The barometer fell 

 0.46 inch at the time, and the thermometer indicated 66' at 

 8.30 A.M. and 6?' at 10.30 p.m. Residents of Cairo said that the 

 sand-storm was the severest in twenty-five years, and of an un- 

 usual character, — being accompanied by a low temperature in- 

 stead of the scorching Khamsin. The following day was clear 

 and cool. The dust penetrated every cranny and gave hotel 

 servants hours of labor. 



I experienced a third sand-storm in the desert of Sinai, on the 

 plain of El Markha ; it was accompanied by a scorching south 

 wind, and the drying effects on the skin and the capital orifices 

 produced greater discomfort than the suffocating dust and 

 cutting sand ; my party could do nothing but sit in silence on 

 our camels, facing the storm, and the poor animals forgot to 

 snatch at the tufts of scanty shrubs, as is their custom. After 



