RuRsegofer's Jifmarlii on the CTimate of Egypt, 95 



to those which are remarkable for the quantity of atmosphe- 

 rical precipitations, and ought, therefore, to be inchided among 

 the exceptions ; so, on the other hand, there are years when 

 these precipitations are particularly rare, and which, there- 

 fore, are also to be regarded as exceptions. We cannot 

 employ either extreme as a guide to enable us to deduce 

 the mean yearly quantity of rain, and conclusions exclusively 

 confined to the one or the other are hence incorrect. The 

 yearly quantities of rain increase by gradations southwards 

 from Cairo towards the tropic, although, however, in the vici- 

 nity of the great river, that is, in the actual valley of the Nile, 

 the rain is more observed than in the deserts on the two sides 

 of the stream. Northwards from Cairo, on the other hand, 

 the phenomena of the true littoral climate extend not only 

 over the Delta, but likewise eastwards and westwards into the 

 deserts, where Ehrenberg, Hemprich, and General Minntoli, 

 suffered not a little from violent rains during their journey to 

 the oasis of Jupiter Ammon.* At an earlier period, this cli- 

 mate, which now belongs to Lower Egypt as a littoral region, 

 would seem to have stretched more to the south ; for we find 

 in Upper Egypt, as well in the valleys of the Arabian as of the 

 Libyan mountains, that is, of the mountains eastwards and 

 westwards of the Nile, the most evident traces of violent falls 

 of rain, viz. many dried up beds of torrents, which, as appears 

 from the boulders transported by them, and from the consider- 

 able ravines which they have furrowed, must have been deep 

 and powerful. 



Barometer. — The conclusion derived from horary observa- 

 tions of the barometer is, that in Egypt, as in every place 

 where I have been able to make observations in Africa and 

 Asia, the pressure of the atmosphere attains twice a-day a 

 maximum and tmce a-day a minimum. The maxima occur 

 at 10 A.M. and 10 p.m., the minima between 4 and 5 p.m. and 

 a little before sunrise, corresponding with the minunum of 

 the daily temperature. Although the differences of the ex- 

 tremes at night are sometimes very small, always much smaller 



^ Journey to the Temple of Jupiter Ammon in the Libyan desert, by 

 Bavon vou Minutoli, Berlin, 1824 ; and Travels in Egypt, liibya, Nubia, and 

 Dongola,, by Hemprich and EUrenberg. 1. vol. I. part. iSeilio, 1828, 



