31 
A projection of these numbers is shown in curve No. 4. 
The means for the seasons are 
Winter 32*0 
Spring 55*9 
Summer 53 - 0 
Autumn 42*5 
It appears therefore that the elevation of the clouds is 
greatest in the spring quarter when the amount of ozone, 
according to the Oxford observations, is also greatest, and 
least in winter when the amount of ozone is also least. I 
am not at present aware of the existence of any observa- 
tions by which it can be ascertained whether this relation 
holds good in other latitudes. 
It may be objected that the conclusions I have drawn 
from the few series of observations to which I have referred 
rest on an insufficient basis of facts : and knowing, from 
long experience in meteorological inquiries, the danger of 
relying too much on deductions from a limited number of 
observations, I regard it as very probable that further 
investigations may render some modifications of my con- 
clusions necessary. The subject is one in which the 
meteorologist requires the aid of the chemist. The method 
now employed of detecting the presence of ozone in the 
atmosphere, and measuring its result, is very imperfect; 
and the causes of its frequent sudden development and 
almost equally rapid disappearance are, at present, involved 
in mystery ; they are, however, as I have shown, evidently 
connected with other meteorological phenomena upon which 
they may throw much light; and their importance in a 
sanitary point of view cannot be doubted. Although, 
therefore, my investigation has failed to establish the 
validity of Mr. Mackereth’s conclusions, it will, I trust, 
serve to show the desirability of giving increased attention 
to observations of atmospheric ozone, and of attempting to 
