25 
Both at Eccles and Oxford the maximum occurs in the 
spring, hut the minimum occurs at Eccles in the autumn 
and at Oxford in the early part of winter. 
The Rev. Robert Main, F.R.S., Director of the Radcliffe 
Observatory, Oxford, has kindly favoured me with a copy 
of the unpublished results of his ozone observations for the 
years 1866 and 1867, and although he believes that 
the results lor 1866 cannot be relied on owing to test 
papers of an unsatisfactory quality having been used during a 
considerable portion of that year, yet the means for the two 
years, which are 4*57 for 1866 and 412 for 1867, bear out 
very fairly the conclusions I have drawn from the results of 
the previous ten years’ observations, the amounts being 
above the average of the entire series, and corresponding to 
a sun spot frequency considerably below the average. 
Observations at the Lisbon Observatory. 
The first volume of the Annals of the Lisbon Observatory 
contains a table of the monthly and annual results of a 
series of ozone observations made during the years 1856-63. 
The mean monthly amounts of ozone were as follows : 
Night. 
Day. 
Mean. 
January 
.... 5*8 ... 
... 5-1 ... 
... 5-4 
February .. 
.... 5-8 ... 
... 5-2 ... 
... 5-5 
March 
.... 5*8 ... 
... 5-0 ... 
... 5-4 
April 
.... 5-8 ... 
... 4-8 ... 
... 5*3 
May 
.... 5-3 ... 
... 4*3 ... 
... 4-8 
June 
.... 4-7 ... 
... 3*8 ... 
... 4-3 
July 
.... 3-8 ... 
... 3-0 ... 
... 3-4 
August 
.... 4*4 ... 
... 3*3 ... 
... 3-8 
September . . 
.... 4-7 ... 
... 3-8 ... 
... 4*3 
October 
... 5-3 .... 
... 4-5 ... 
... 4*9 
November .. 
.... 6-0 .... 
... 5*3 ... 
... 5-6 
December .. 
.... 5*7 .... 
... 5-0 ... 
... 5-3 
Year 
.... 5-3 .... 
... 4-4 ... 
... 4-8 
