188 



Judging from my own experience, derived from observations 

 daring a long term of years, I should say that sudden thaws, 

 after frosts of some continuance — and yet more after frosts of 

 long continuance — are the occasions (jeneralhj on which occur the 

 greatest depressions of the Barometer; and, what is more, that 

 the greatest elevations also, as well as lowest, mostly occur in 

 winter. This makes it of interest to notice how far this is the 

 case in the table of maxima and minima during the eleven years 

 1875 — 1885. It will be seen on inspection that the maxima 

 occurred five times in January, twice in December, twice in 

 October, once in February and once in May. The minima 

 occurred four times in February, three times in November, twice 

 in January, once in December and once in April. Perhaps this 

 will appear plainer when set out as under, alotting the three 

 usual months to each season : — 



Spring. Summer. Autumn Winter. 



Maximum... 1 ... ... 2 ... 8 

 Minimum ... 1 ... ... 3 ... 7 



2 5 15 



Thus, not only are the greatest elevations and depressions 

 clearly in excess in winter ; but with the two exceptions of one 

 high elevation in May and one depression in April, there are no 

 extremes one way or the other to be found between the months 

 of February and October. 



The mean height of the Barometer for each season on an 

 average of eleven years, which it may be useful to record, is as 

 follows : — 



Spring ... ... ... 29-958 



Summer ... ... ... 29-973 



Autumn 29-961 



Winter ... ... ... 30-010 



