24 
1858-62 with those for the years 1856-7 and 1868-5, we 
have the following results : 
Mean Annual 
Value of 
Mean Annual 
Value of 
Ratio of 
Day Amounts 
Night Amounts 
Day to Night 
of Ozone. 
of Ozone. 
Amount. 
Years 1858-62.. 
2*52 ... 
... 3-57 ... 
... 0-70 
Years 1856-7 i 
V 
4-24 
4 ’01 
1-05 
and 1863-5 j 
Differences 
1-72 
.... 0-24 
It appears therefore that in years of maximum solar radi- 
ation and sun-spot frequency the day amount of ozone is only 
seven-tenths that of the night, while in years of minimum 
it is slightly in excess of that for the night ; and also that 
while the difference between the night amounts of the two 
periods is only 044, that between the day amounts is 1*72, 
or nearly four times greater. The effect therefore of an 
increase in the frequency of solar spots appears to be to re- 
duce the amount of atmospheric ozone to a much greater 
extent during the day than during the night. 
Admitting that a connexion exists between the frequency 
of solar spots and the amount of ozone in the earth's atmo- 
sphere, it will be seen that the amount of ozone was excep- 
tionally low in 1857 and exceptionally high in 1868. The 
anomalous action which produced the unusually high rate 
for 1868 would no doubt extend its influence to Eccles and 
produce an exceptionally high amount o*f ozone at that 
station, which, as Mr. Mackereth’s series commenced in 1863, 
has evidently misled him as to the true nature of the con- 
nexion between solar spot frequency and the amount of 
atmospheric ozone. 
Grouping the Eccles and Oxford monthly means according 
to the seasons, we have the following results : 
Eccles. 
Oxford. 
Winter 
.... 1*28 ... 
... 2-75 
Spring 
.... 2-13 ... 
... 4*56 
Summer 
.... 1*37 ... 
... 4-23 
Autumn 
.... 0-89 ... 
... 2-90 
