27 
The slight difference between these two numbers shows 
that the amount of ozone at Lisbon is but slightly affected 
by the frequency of solar spots. The mean value, however, 
for years of maximum solar spot frequency is slightly greater 
than that for minimum years; but we have seen that at 
Oxford the value in the former case was considerably less 
than in the latter. This circumstance, taken in connexion 
with the difference in the epochs of maximum and minimum 
of the annual curves of the two stations, has suggested to my 
mind, the idea of a belt of ozonized air in the middle lati- 
tudes of our hemisphere, which has a motion to the north- 
ward during the spring months of the year, and a return 
movement to the southward during the autumn months, and 
that its mean position for the year varies with the increase 
or decrease of solar spot frequency; or with the increase 
or decrease of the disturbances in the earth’s magnetic 
elements. 
Observations at Hobart Town , Tasmania, 
A valuable series of ozone observations was made at 
Hobart Town, Tasmania, by Mr. Francis Abbott, F.R A. S., 
during the years 1858-65, and part of the year 1857, from 
which he deduced the following mean monthly values of 
the amount of atmospheric ozone at that station, the numbers 
being the sums instead of the means of the day and night 
values : — 
January 
... 6-89 
July 
... 7-09 
February 
... 7 01 
August 
... 7-52 
March 
... 7-01 
September . . . 
... 7-96 
April 
... 6*99 
October 
... 7-92 
May 
... 6-80 
November 
.. 7-56 
June 
... 6-50 
December . . . 
... 7-19 
7*18 
