THE SOURCE OF THE NILE. %%f 



The porphyry fhews itfe-lf by a fine purple fand, without 

 any glofs or glitter on it, and is exceedingly agreeable to the 

 eye. It is mixed with the native white fand, and fixed gra- 

 vel of the plains. Green unvariegated marble, is generally 

 feen in the fame mountain with the porphyry. Where the 

 two veins meet, the marble is for fome inches brittle, bat 

 the porphyry of the fame hardnefs as in other places. 



The granite is covered with fand, and looks like Hone of a 

 dirty, brown colour. But this is only the change and impref- 

 fion the fun and weather have made upon it; for, upon break- 

 ing it, you fee it is grey granite, with black fpots, with a red- 

 diih call, or bluih over it. This red feems to fade and fuf- 

 fer from the outward air, but, upon working or polifhing 

 the furface, this colour again appears. It is in greater 

 quantity than the porphyry, and nearer the Red Sea. Pom- 

 pey's pillar feems to have been from this quarry. 



Next to the granite, but never, as I obferved, joined with 

 it in the fame mountain, is the red marble. It is covered 

 with fand of the fame colour, and looks as if the whole 

 mountain were fpread over with brick duft. There is alfo 

 a red marble with white veins, which I have often feen at 

 Rome, but not in principal fubjects, I have alfo feen it in 

 Britain. The common green (called Serpentine) looks as if 

 covered over with Brazil muff. Joined with this green, I 

 faw two famples of that beautiful marble they Call Ifabella; 

 one of them with a yellowifh call, which we call Quaker- 

 colour ; the other with a blueilh, which is commonly termed 

 Dove-colour. Thefe two feem to divide the respective 

 mountains with the ferpentine. In this green, likewife, it 

 was we faw the vein of jafper ; but whether it was abfolute- 



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