212 



occasionally a squally wind, occasioning some danger to 

 our boats. During the night there was a very heavy 

 shower, and on the following day two more such. 

 Lepsius writes, " At Assouan we were obliged to change 

 our boat on account of the cataracts, and for the first 

 time for six months past, or longer, we had the home en- 

 joyment of heavy rain and a violent thunderstorm, which 

 gathered on the farther side of the cataracts, crossed with 

 a mighty force the granite girdle, and then, amidst the 

 most violent explosions, rolled down the valley as far as 

 Cairo, and (as Ave have since heard) covered it with 

 floods of water, such as had been scarcely remember oJ 

 before. So we may say with Strabo and Champollion, 

 ' In our time it rained in Upper EgyjDt.' Rain is, indeed, 

 so rare here that our guards never remembered to have 

 beheld such a spectacle." 



Lightning and thunder, especially the latter, are, how- 

 ever, extremely rare in Upper Egypt, and it is mentioned 

 by Ayme (Description d' Egypt I. 135) that, during two 

 yeais he heard only a single clap of thunder, and that so 

 faint as to escape the notice of several persons around 

 him. 



A clear sky and high daily temperature of the air are 

 favourable to the development of heavy dews, and are 

 consequently miicli seen in middle and loAver Egypt, 

 especially when the north or west winds blow, as they 

 come from the Mediterranean, surcharged with moisture. 

 On the contrary, dew is nearly altogether absent when 

 the winds blow from the south or the east, as the hot and 

 arid sands of the desert completely desiccate them before 

 they reach the Nile valley. There is also little or no dew 

 in Nubia, except on the river, and that is so slight as 

 scarcely ever to leave any perceptible moisture on the 

 boat. Volney has stated that dews are most frequent in 

 Egypt during the summer, but this is altogether incorrect, 



