THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 



259 



Hence the absolute highest pressure was 30 "11 3 inches on 3rd October at 9 p.m. and 

 the lowest 28 '281 inches on 3rd July at noon. The monthly range is moderate, and was 

 greatest (1-669 inch) in October 1903, and least (0-930 inch) in January 1904. The 

 mean pressure varies but little with the season, the values being. Spring 29-232 inches, 

 Summer 29-174 inches, Autumn 29-213 inches, and Winter 29-234 inches. In 1903 the 

 conditions were eminently cyclonic and the islands were on the edge of the pack, but 

 in 1904 the ice extended a long way to the north, which doubtless exerted a material 

 influence on the pressure, probably through the course taken by cyclonic systems being 

 diflferent. The following are the monthly means after March 1904 : — 



Comparing the seasonal means, it will be seen that the excess of pressure in 1904 as 

 compared with 1903 was -043 inch in Autumn, -131 inch in Winter, and -193 inch in 

 Spring, the maximum excess in any month being in November, which had a pressure 

 0-464 inch higher than in the same month of 1903. 



Taking seasonal means for each hour in the day, we obtain the following values : — 



