12 



BOTANICAL FEATURES OF THE ALGERIAN SAHARA. 



range of 19. 4 C. was reported in April, 20. 2 C. in June, 21. 8° C. in July, 

 and 20.2 C. in December. Except in December, the great ranges in tem- 

 perature here cited were on days when the sirocco was blowing from the 

 desert; hence, the usual daily range in temperature would be much less. 

 In the Tell, and especially along the coast, the range in temperature re- 

 corded for any day is relatively little, although at the time of the sirocco, 

 as well as during the season of drought, the daily range is not inconsider- 

 able. Table 8 gives the maximum daily range for the months of 1904, for 

 two stations, along the coast, including the Tell, and two stations on the 

 High Plateau. The daily range reported for Batna in June, July, and 

 August, 1902, was somewhat larger than the maxima given in table 8. In 

 1902 the maximum daily ranges in temperature for the three months at 

 Batna were 23. 9 C, 25. 3 C, and 24. 4 C. 



The temperature conditions for the year 1908 will serve very well to 

 further illustrate this phase of the climate of Algeria. No freezing temper- 

 atures were reported from the coast stations, although at the northern 

 base of the Atlas of the Tell several degrees of frost were recorded. At 

 Blida, for example, the thermometer registered -4.0 C. as the minimum. 

 Away from the littoral at every station whose records were seen the lowest 

 temperatures were zero centigrade, or below. The coldest weather was 

 felt at Aflou, at the north base of the Dj. Amours, of the Saharan Atlas, 

 where -11.0 C. was reported. The summer was warm along the coast 

 and hot in the interior. The records of temperature of 23 stations of the 

 Tell were seen, and of this number, at only 8 was a temperature of 40 C. 

 reached or exceeded. On the other hand, at 44 out of 56 stations on the 

 High Plateau and the desert, the temperatures reported are as great or 

 greater than 40 C. Where temperatures below this figure were recorded 

 the stations were situated in the mountains. 



The western portion of the Sahara is apparently not so hot as the eastern 

 portion. The mean annual temperature for Biskra is 20.3 C. ; for Ghardaia 

 it is 21 C. ; for El Golea it is 22.2 C; and for Touggourt it is 23. 4 C. 

 The mean temperature at Cairo is 21.3 C; for Suez it is 21. 5 C. ; and for 

 Djedda, on the Red Sea, it is 27.3 C. The absolute maximum tempera- 

 tures in southern Algeria for as many years and for two of the most south- 

 ern army posts, El Golea and In Salah, are as follows: El Golea, 47 , 46.5°, 

 48 , and 49. 2 C. ; In Salah, 50.0 , 49. 2 , 50.2°, and 48 C.; at Ouargla the 



