CHILL OF THE DESERT NIGHTS. 75 



handles split, and paper breaks when crushed up in the hand." * 



On his return from the Nile sources Sir Samuel Baker 

 found the thermometer, at Suakin, marked 115 Fahr. 



We might largely increase the number of instances 

 where these intense heats are recorded, by quotations 

 from the works of various authors, did not time and 

 space forbid. What we desire, however, more parti- 

 cularly to point out, is that where these great heats do 

 occur, they are certain when they are not accompanied 

 by hot winds to be compensated for by the occurrence 

 of cool nights: because the same cause which operates 

 to produce these extreme temperatures by day, namely, 

 the want of aqueous vapour in the atmosphere, is 

 sure to create an exceedingly rapid radiation of heat 

 the moment the shadow of the earth intervenes to 

 shield us from the fierce rays of the sun and although 

 the ground may have been heated ever so much dur- 

 ing the day, the temperature falls so rapidly by night, 

 that towards morning the traveller is often glad of 

 all the extra coverings he can obtain. 



The German traveller Dr. Barth, for instance, after 

 describing the great heat of the desert in Southern 

 Tripoli, mentions that the guide of the Arab caravan 

 " begged me to beware of the cold during the night, 

 which he represented as very intense, " f and it is a 

 fact well known to all travellers that though the heat 

 in the Sahara is often very extreme by day, yet the 

 nights are uniformly cold, when the hot wind does not 



* The Nile Tributaries of Abyssinia, by Sir Samuel Baker, 1887, 

 P. I?- 



f Travels in Africa (1849 to 1855), by Dr. Barth, Vol. i, p. 185. 

 (Undertaken under the directions of H.B.M. Government, and published 

 1857-8). 



