( 633 ) 



The Meteorology of Glen Nevis from October 1901 to February 1902. 



By R. C. Mossman. 



While meteorological observations taken in deep narrow valleys are open to grave 

 objection for many meteorological purposes, iDcluding the drawing of isobaric and 

 isothermal charts, yet the study of the climatic features in such a locality presents 

 several points of special interest. This is more notably the case in the present instance 

 owing to the close proximity of the Ben Nevis Observatory and the low-level 

 Observatory at Fort- William. As the latter was only about 4|- miles distant 

 from the valley station, the peculiarities of the climatology of Glen Nevis could be 

 studied with a confidence which would have been unattainable without this adjoining 

 sea-level station. 



The series of observations under discussion were commenced on 3rd October 1901, 

 and continued till the end of February 1902. The choice of a site was limited by the 

 ability to obtain accommodation, but, as will be seen from a discussion of the results 

 obtained, it would hardly have been possible to have had a station more admirably 

 placed for the study of valley conditions than was the hamlet of Achariach. Through 

 the courtesy of Mr Sinton, the then tenant of Glen Nevis House, a site for the 

 instruments was obtained in close proximity to the cottage. 



Preliminary papers on the observations were communicated to the Scottish 

 Meteorological Society on 20th March 1902, and to the Royal Society of Edinburgh 

 on 19th May 1902. 



Position of Station and Natural Features. 



Achariach is situated in lat. 56° 46' N., long. 5° 3' W. The nearest town is Fort- 

 AVilliam, which is distant 4^ miles to the north-west as the crow flies, while by road 

 the distance is 7 miles : about 2^ miles north-east is the high-level observatory on 

 Ben Nevis. Bartholomew's Reduced Ordnance Map of Scotland, sheet 15, from which 

 the annexed sketch-map is taken, gives an excellent picture of the depth and narrowness 

 of the valley. The height of the barometer at the valley station was 150 feet above 

 mean sea-level, or 108 feet higher than that of the Fort- William Observatory. While 

 the more local surroundings were somewhat open, the station was surrounded and shut 

 in by high mountains ranging from 3000 to 4400 feet in height. The position of 

 Ben Nevis with regard to the station has been already noticed. The principal peaks 

 in the immediate vicinity were the Cairn Dearg of Ben Nevis, with a height of 3348 

 feet, 1^ miles to the N.N.E. ; 2 miles to the S.E. is Sgor-a-Mhaim (3601 feet) ; 



