240 
heights. It is supposed by some meteorologists that the mild 
temperatures of the higher latitudes of western Europe are 
due to the heat which is liberated by the condensation of 
vapour during the frequent precipitations of rain, which take 
place on or near the coasts ; but if this view were correct, the 
mean temperature of rainy days ought to be considerably 
greater than the mean temperature of the year. 
A discussion of the Greenwich Observations for the years 
1852, 3, and 4, and of the Oxford Observations for 1855, 6, 
and 7, with reference to this point, has given the following 
results : — 
GREENWICH OBSERVATIONS. 
YEAR. 
Number 
of 
Rainy days. 
Mean temp, 
of 
Rainy days. 
Mean temp, 
of 
the year. 
1852 
152 
5°l-39 
50-66 
1853 
184 
47-62 
47-49 
1854 
145 
48-80 
48-80 
General Means. 
160-3 
49-27 
48-98 
OXFORD OBSERVATIONS. 
YEAR. 
Number 
of 
Rainy days. 
Mean temp, 
of 
Rainy days. 
Mean temp, 
of 
the year. 
1855 
140 
4°9-84 
4°7-10 
1856 
154 
49-09 
48-70 
1857 
146 
49-96 
50-40 
General Means. 
146-6 
49-63 
48-73 
It appears, therefore, that the excess of mean temperature 
of rainy days, over the mean temperature of the year, on an 
average of three years, is only 0°’29 by the Greenwich obser- 
vations, and 0°'90 by the Oxford observations; but as the 
