CH. IX. HEIGHT OF TAGHEROT PASS. 227 



giving for the Tagherot Pass 5,021 feet above Arround, or 

 11,484 feet (3,500-4 m.) above the sea. 



In Appendix A the reasons which showed the necessity 

 for a considerable correction to the original observations 

 made since our arrival at Mogador are fully explained. 

 The difference in the resulting heights throughout our 

 journey is not of much moment as regards the lower 

 stations ; but it increases rapidly with increasing altitude, 

 and in the case of the Tagherot Pass amounts to about 

 500 feet. As this correction was disclosed only after 

 careful examination and compai'ison of all the observa- 

 tions, the first result, which was derived from the rough 

 reduction made at the time, communicated in a letter from 

 Hooker to the late Sir Roderick Murchison,' and which 

 appeared in other published notices of our journey, is 

 probably erroneous to the extent above mentioned. 



Assuming our final results to be pretty nearly correct, 

 and having been unable to hear of any other easy or 

 frequented pass in this part of the range, we seem to 

 be justified in concluding that this section of the Great 

 Atlas chain, as compared with any of the mountain 

 systems of Europe, maintains a remarkably high meani 

 level. The height of the projecting summits in the 

 adjoining portions of the chain was variously estimated 

 by us at 1,500 or 2,000 feet above the Tagherot Pass. 

 Taking the lower of these estimates, and assuming the 

 other depressions to be no higher than Tagherot, we 

 should have for the mean height of the main ridge at 

 least 12,200 feet. Judging from all the distant views we 

 were able to obtain, the portion of the Atlas chain near the 

 head of the Ait Mesan valley is very similar in character 

 to that extending eastward to the sources of the Oued 

 Tessout, and does not reach a higher elevation. If this 

 opinion be well founded, we have in this part of the Great 



' Printed in the Proceedings of the lloijal Geograjihical Society, 

 for 1871. 



