ON METEOROLOGICAL OBSERVATIONS ON BEN NEVIS. 



317 



at Fort William. Having hitherto only had five observations a day from 

 the Low Level Station, it was of course impossible to investigate the pro- 

 gressive changes of the vertical gradients from hour to hour, and conse- 

 quently also impossible to turn the observations of the Ben Nevis Obser- 

 vatory to their proper account in forecasting weather. With the opening 

 of the Low Level Observatory will commence a new era in the work of 

 the Ben Nevis Observatory. It will then be possible by the double set 

 of horizontal meteorological gradients and vertical meteorological gra- 

 dients thus obtainable to examine more fully and rigorously the atmo- 

 spheric changes which precede, accompany, and follow the passage across 

 these islands of the cyclones and anticyclones of North-Western Europe. 

 For the year 1888 the following were the monthly mean pressures 

 and temperatures, the amounts of the rainfall, and the hours of sunshine, 

 the pressures at Fort William being reduced to 32° and sea-level, those of 

 the Ben Nevis Observatory to 32^ only : — 



Tahle of Mean9, 1888, Ben Nevis Observatory and Fort William. 



Jan. Feb. |Maroh| April I May | June July | Aug. I Sept. Oct. I Nov. I Dec. Year 



Mean Pressure in Inches. 



Ben Nevis Ob- 

 servatory 

 Fort William 

 Difference . 



25-167 1 25-391 1 25-036 



30-1(mI 30-078 23-660 

 4-637| 4-687I 4-625 



25-2711 25-359 



29-880 29-925 

 4-609 4-566 



25-453] 25-265 

 29-962 29-740 



25-378 2o-590| 25-367 



29-881 

 4-5091 4-475| 4-503 



Mean Temperature. 



30-132 29-915 

 4-542I 4-548 



25-0691 25-1821 25-318 



29-6361 29-754 

 4-567; 4-572 



Mainfall in Inches. 



Ben Nevis Ob- 

 servatory 



Days of no 

 Rain 



Fort WilUam 



Hours of Sunshine to nearest Whole Hours at Ben Nevi^ Observatory 



68 I 126 I 250 I 69 | 

 426 1 6U8 I 529 | 528 | i 



Maximum Temperature 



No. ot Hours I 70 

 Possible Hours] 231 



73 



275 



64 

 365 



72 

 467 



121 



381 



28 

 319 



8 

 242 



21 



210 



Ben Nevis Ob- 

 servatory 

 Fort Will.ara 



Ben Nevis Ob- 

 servatory 

 Fort William 



Minimum Temperature. 



9-6 

 17-7 



10-1 

 11-7 



7-2 

 21-2 



14-2 

 26-2 



19-2 

 32-2 



23-5 

 35-2 



26-2 

 38-3 



29-6 

 36-2 



21-3 

 83-2 



lG-2 

 34-2 



18-3 

 28-2 



16-6 

 220 



29-889 

 4-5 JO 



31-1 



46-2 

 15-1 



132-46 

 118 

 70-23 



970 

 4,470 



Gl-1 

 85-8 



7-2 



n-7 



At Fort William the mean annual temperature was 46°-2, being the 

 same as last year, which was a degree under the average. The mean at 

 the Observatory was also the same as on the previous year. In no month 

 did the mean temperature at the Observatory rise to 40°0, the highest 

 being 39° G in June ; and it is remarkable that this and three subsequent 



