OC 



70 



DECEMBER 



MARCH 



AUGUST 



I 



BLACK 

 BULB 



op 



170 



160 



150 

 140 

 130 



120 

 110 



100 



90 



80 



70 



60 



50 



40 

 OF 



60 



50 



r BLACK 

 * BULB 



I 



WHITE 

 BULB 



40 



30 



WHITE 

 BULB 



R 



W 



T * 



5 r 



20 



10 



OC 



S W 



1 . " - 



I 



s 



T W 

 ;; T R 

 j: T 



_A B_ 



NESTS 



SAND 



DECEMBER 



CAVE 



B 



I 



* : : 



& 



A i: 



NESTS 



CAVE 



SAND 



» -^ ■*" t CAVE 



NESTS SAND 

 MARCH 



AUGUST 



Figure 1. 



Wadi Digla near Cairo. Temperature Conditions in Desert. 



S = Screen W = Shade in Wadi R = Under Rock. Nests, A = Bush B = in Hole in Rock 



Sand at 1. 10. and 20 cms. Cave at Mouth, 5 and 12 metres in. 



Fig. 2 shows the hour by hour changes in temperature in some of these locations 

 during five days in August. Apart from the great daily range of temperature in the 

 places exposed to the sun, there should be noted the low range but high average tem- 

 perature in the Jerboa burrow, and the low range and low average temperature in the 

 sand in the shade, as shown by the ant-lion pit. It is also interesting to note that the 

 maximum temperature at the end of the Jerboa burrow (which was estimated to be about 

 23 cms, below the surface) occurred about 9-10 p.m. and the minimum about 8-9 a.m., 

 the former about 8 hours and the latter about 4 hours later than the corresponding stage 

 at the surface. 



20 



