50 REPORT— 1900. 



the average, at tlie neighbouring surrounding stations near sea level the 

 rainfall was about 10 per cent, under the average. It will be observed 

 that the large excess on Ben Nevis was almost wholly occasioned by the 

 extraordinarily heavy rainfall there in November and March. In these 

 months there prevailed over Scotland an unusual excess of south-westerly 

 winds. The largest monthly rainfall, 32-48 inch, occurred in November, 

 when south-westerly winds prevailed eight days more than the average, 

 and the mean temperature of the month over Scotland was 46°"4, or 5° 8 

 above the average of the month, an excess of south-westerly winds and of 

 mean temperature hitherto unparalleled for November. The heaviest 

 rainfall on any single day was 4"68 inches in December. At Fort 

 William the annual rainfall was 74"58 inches, and the largest monthly 

 amount was 13-27 inches in November, when the rain-bringing south- 

 westerly winds were so prevalent. The heaviest fall on any single day 

 was 1-63 inch in March. 



At the top of Ben Nevis rain fell on 253 days, and at Fort William 

 on 223 days. At the top the monthly maximum was 28 days in September, 

 and the minimum 11 days in February, and at Fort William the 

 maximum was 26 days in September, and the minimum 12 in August. 



During the year the number of days on which 1 inch of rain or more 

 fell was 66 at the top and 12 at Fort William, the former being 18 above 

 the average and the latter 5 below it. 



Auroras were observed on the following dates : — February 1 2 ; March 

 10, 16, 21, 22 ; May 2, 3, 4, 5, 6 ; and October 15. 



St. Elmo's Fire was seen on January 6, 13, 15 ; March 28 ; August 25 j 

 September 19, 20, 23 ; October 30 ; and November 6, 8, 10, 11. 



Zodiacal Light : — On October 15. 



Thunderstorms : — On August 25 ; September 17, 18 ; and October 

 13, 30. 



Lightning only : — On January 16 ; February 12 ; and September 29. 



Solar Halos :— January 2; March 30; April 9, 12, 18, 19, 20, 22; 

 May 9, 12, 22, 31 ; June 10, 17 ; July 6 ; and August 5, 18. 



Lunar Halos :— January 17, 26, 27, 28 ; February 18, 21, 22 ; March 

 24 ; April 19, 20 ; June 27 ; October 21, 22 ; November 9 ; and Decem- 

 ber 10, 12, 13, 23. 



Much time has been taken up in revising the proof-sheets of the 

 hourly observations of the Ben Nevis Observatories now in the press, and 

 the work of printing is proceeding at a fairly satisfactory rate. It need 

 scarcely be added that the revision of the work, which will fill three large 

 quarto volumes, is peculiarly heavy. The work of reduction and entering 

 on daily sheets the hourly observations of the two observatories is practi- 

 cally brought down to date. The daily maps of rainfall, fog, storms, and 

 other weather phenomena are also completed to date ; and for several 

 selected months there are already entered on the same maps the details 

 for storms, forecasts, and storm warnings. With these are compared the 

 hourly observations at the two observatories with the view of arriving at 

 some definite knowledge of the relations existing among the phenomena 

 observed. Particular attention is given in the first place to the relations 

 between the double set of observations made at Ben Nevis and the fore- 

 casts and warnings issued from the Meteorological Office in London of 

 storms, rain, fog, and other weather phenomena. 



For several months Mr. Omond had under discussion all hourly tem- 

 peratures observed at Fort William and the top of the mountain, showing 



