OF LOCHABER. 



make the section of the line of their profile somewhat like 

 this : 



And every part of the breadth of the shelf also, deviates so far 

 from the level, that the sections of it would exhibit an inclina- 

 tion outwards of from one foot in five, to one foot in three, 

 and in some places a great deal more. Their actual surfaces 

 are all so rugged and irregular, that no proper series of opera- 

 tions could be carried along any of them, with a hope of de- 

 termining their true linear level. My friend Mr Maclean 

 and I, therefore, conceived that we did nearly all that could be 

 well accomplished for this purpose, by using the following 

 means, in the course of three several observations, taken on 

 shelf 2d, shelf 3d, and shelf 4th, which, together with the re- 

 sults, I shall now detail. 



It was from a very commanding position, marked d on the 

 map, that we levelled shelf 2d. From this point we enjoyed 

 very nearly the same view as that represented in plate IV., and 

 had the advantage of observing some considerable portions of 

 the same shelf on the other side of the valley, immediately op- 

 posite to the eye, and at no great distance from it, whilst there 

 were also a variety of different distances, receding in perspec- 

 tive behind one another. We employed a very delicate eigh- 

 teen 



