OP LOCHABEll. 9 



been extended, would have stretched perhaps five or six miles, 

 whilst, from its numerous bendings, the rectilineal distance of 

 the farthest visible part of it from the eye, was probably not 

 so much as two miles, and most of it was greatly less than one. 

 And what was still more advantageous in this position, in tra- 

 versing the telescope of the instrument round, many points 

 could be touched upon which were evidently nearly equidistant 

 from the eye. Here the perfect coincidence of the line with the 

 horizontal hair, was more generally striking than it was in our 

 first experiment. 



Our third trial was on shelf 4th, and we were fortunate in 

 selecting a very excellent point of view for that also. The 

 spot where we planted our instrument was a little to the east- 

 ward of the house of Inch, on the south side of the entrance 

 of Glen Spean, (see b in the map). It was from thence that 

 I sketched the view of the entrances of Glen Roy and Glen 

 Spean, as represented in Plate II., which, when compared with 

 the map itself, will afford some idea of the great extent of 

 shelf 4th, which we commanded at one coup cTceil. We could 

 trace it, sweeping from Ben-y-vaan on the left, up Glen Col- 

 lerig, — returning from that little valley, and embracing the 

 south side of the round hill of Bohuntine, and disappearing 

 into Glen Roy, — re-appearing on the faces of its southern 

 mountains, till it is again lost behind that of Crag-dhu, which 

 divides the entrances of the two glens, — coming into view 

 again as it circles round the bottom of that projection, and 

 identifying itself with the upper line of a high inclined plane, 

 whence it sweeps into the mouth of Glen Spean, where we 

 could of course trace it much farther, than could be embraced 

 within the angle of vision employed in the delineation of a 

 perspective sketch. We could also trace the same line faintly 

 encircling the isolated rock of Mealderry, which appears in 

 the drawing much nearer the eye. We traversed the telescope 



VOL. IX. p. i. b of 



