Ouchullin Hills in Skys, 81 



3000 feet. In 1843, I was in Skye with a barometer, but 

 had not an opportunity of revisiting the Cuchullins ; but in 

 May 1845, I ascended the lower summit, nearly adjoining^ 

 marked Bruch-na-Fray in the map, and wishing to ascertain 

 the difference of height of Scuir-na-Gillean, I proposed to 

 Maclntyre to try to ascend it from the west side. It was 

 no sooner proposed than attempted. It was impossible to 

 do otherwise than descend deep into the rugged ravine of 

 Loat-o-Corry, which separates them, which cost us a severe 

 scramble, and then face an ascent, which from a distance 

 appeared almost perpendicular ; but aided by the quality of 

 the rocks already mentioned, we gained the Scuir-na-Gil- 

 lean from the west side, although, on reaching the top, and 

 looking back, it appeared like a dizzy precipice. My barome- 

 trical observations were unfortunately rendered somewhat 

 unsatisfactory, by the comparison of the height of the mer- 

 cury at starting and returning to our fundamental station at 

 Sligachan Inn. There appeared to have been a great fall 

 during the ten hours that I had. been absent ; and in such 

 circumstances, interpolation for the height of the barometer 

 at the lower station is always uncertain and inconclusive. 

 A very rigorous comparison which I hav« made of all the 

 readings of the barometer before, at the time of, and after, 

 the observations, do not allow me to attribute any probable 

 error to the observations themselves, nor any probable in- 

 jury to the barometer, which seemed to have as good a va- 

 cuum after my return as before ; but another check remained. 

 My friend, Mr Necker, foreign member of this Society, be- 

 ing then resident at Portree, and having a barometer similar 

 to mine (on Bunten's construction) which he observed from 

 time to time, and with which mine was compared some days 

 after, and found to agree to within 012 inch, kindly allowed 

 me to make use of his observations. Though the barometer 

 was falling at Portree (10 miles distant) at the time, there 

 did not appear to have been the great and sudden change 

 which I observed. Nevertheless, fully acknowledging the 

 difficulty, I am disposed to think that some local rarefaction, 

 not unfrequent in climates so agitated, and in localities so 

 mountainous as Skye, produced the fall in the barometer 



VOL. XL. NO. LXXIX. — JANUARY 1846. F 



