10 J. MILNE ON THE SINAITIC PENINSULA AND N.W. AKABIA. 



Harra of Autas. 



Harra of Abbad. 



)? 



Tabuk. 



Udhra. 



J5 



Takda or Nudka. 



„ Asas. 



J5 



Hakl. 



„ Gallas. 



l> 



al-Himara. 



„ Kuba. 



>> 



Eagil. 



„ al-Kaus. 



>> 



Rahis, 



,, Lubu. 



)> 



Ragla. 



„ Laflaf. 



J» 



Rumah. 



,, Laila. 



>> 



Sulaim. 



„ Masar. 



?J 



al-Sarg. 



„ Maitan. 



5> 



Sauran. 



,, Wakim. 



5? 



Darig. 



„ al-Wabana. 



J» 



Dargad. 



„ Banu Hilal. 



Referring to the above list I may quote the following paragraph 

 from Br. Beke's pamphlet ' Mount Sinai a Volcano ': — 



" Among the numerous volcanoes found to exist within the 

 Arabian peninsula, the only one known to have been in activity 

 within the historic period is the Harra t el Nar (' fire -harra ') 

 situate to the north-east of Medina in the neighbourhood of Khaibur, 

 in about 26° 30' north latitude, and 40° east longitude; which, 

 besides being traditionally said to have been in an active state six 

 centuries before Mohammed, had actually an eruption in the time 

 of the prophet's successor, Omar. To the north-west of this ' fire- 

 harra' lies that known as the Harra of (the tribe of) Udhra: 

 again, to the north of this, is the Harra of Tabuk, so called from 

 the station of that name in the Hadj road from Damascus to Mekka, 

 the position of which is about 28° 15' north latitude and 37° east 

 longitude ; and beyond this last, further to the north, and con- 

 sequently between it and the northernmost Harra of Radjil, or 

 Trachonitis, is the Harra Radjla." 



Rocks from Bit el Mashiyah. 



(These are all taken from dykes. The first two have been determined 

 microscopically.) 



1. Diorite, a greenish -grey compact rock, the character of which is almost en- 



tirely disguised. 



2. Felsite with epidote and chlorite. In general appearance this is a compact, 



fine-grained, light-green rock, not unlike an epidosite. 



3. Porphyritic micaceous granite. The base of this, through which large white 



crystals of felspar are disseminated, is irregular in texture, being mostly 

 composed of small flakes of a dark-coloured mica. 



4. Porphyry consisting of a compact, dark purple base, and well-defined crys- 



tals of pink orthoclase. 



Omaider to ATcaha. — Opposite to Omaider on the Sinaitic side, flat- 

 topped outliers are to be seen capping the granite. These are of a 

 yellowish colour and apparently soft, and at this place show a regular 

 stratification, dipping 3° or 4° towards the north. In the distance, 

 between gaps in these hills a long flat-topped mountain or edge of 

 a tableland is visible, apparently composed of the same material as 



