56 



REPORT — 1901. 



and pressure ; the amounts of rainfall, the number of days of rainfall, and 

 days on which it equalled or exceeded one inch ; the hours of sunshine ; 

 the mean percentage of cloud ; the mean rainband ; and the mean velocity 

 in miles per hour of the wind at the top of the mountain. The mean 

 barometric pressures at Fort William are reduced to 32° and sea level, but 

 those at Ben Nevis Observatory to 32° only. 



At Fort William the mean atmospheric pressure was 29-831 inches, 

 or 0-026 inch under the average. The mean at the top was 25-275 inches, 

 or 0031 under the average. The mean difference for the two observa- 

 tories was 4-556 inches. At the top the absolutely highest pressure for 

 the year was 25-974 inches in March, this being the highest hitherto 

 recorded in March, and the lowest 23 972 inches in December ; and at 

 Fort William the highest was 30-687 inches, and the lowest 28-411 inches 

 in the same months, the differences being respectively 2002 inches and 

 2-276 inches. 



The deviations of the mean temperatures of the months from their 

 respective averages are shown in Table II. : — 



January . 



February . 



March 



April 



May 



June 



February was the coldest month, the temperature at both observa- 

 tories being 5°-0 under the average. In this month south westerly winds 

 were six days short of their average prevalence, and northerly winds four 

 days in excess. Hence the unusually low temperature which was equally 

 felt both at the foot and top of Ben Nevis. On the other hand, temper- 

 ature was above the average in the four months from June to September, 

 the excess l°-6 at the top of Ben Nevis, but only 0°-6 at Fort William, 

 the difference being due to the frequent occurrence of the anticyclonic 

 type of weather during the summer of 1900. The absolutely highest 

 temperature for the year at Fort AVilliam was 79°-0 on June 13, and at 

 the top 61°-0 on August 13 ; and the lowest at Fort William 10° -0 on 

 February 10 and 12, and at the top 6°-0 on February 7. 



In Table III. are given for each month the lowest observed hygro- 

 nietric readings at the top of Ben Nevis : — 



Table III. 



