988 SOURCES OF THESE CHARACTERS. 
late in the last mentioned year, or at all events were 
not seen or heard till after their usual periods. It is 
much easier to state facts than to assign reasons for 
facts, and so in the present case it will be found 
rather speculative to trace out the sources of these 
characters of our climate, and which it is requisite 
to do, because these sources will be found in the 
other physical conditions of the country, themselves 
also influential on the geography of animals, 
proving as before said that these secondary causes 
do not act independently of each other. 
The great source of the general equability and 
mildness of our climate is certainly our connexion 
with the sea. The humidity of the air is referable 
also to the adjacency of the ocean, the sea winds 
conveying with them the continued exhalations 
from its surface; but it depends likewise on the 
presence of our hills, which are great accumulators 
of vapour and attractors of the lower clouds. A 
great influence is also exerted by our inland waters 
which exhale considerable quantities of moisture. 
Lastly, the great abundance of trees, and of vege- 
tation generally must have the effect of condensing 
a large quantity of vapour, and of collecting a great 
quantity of rain, and subsequently yielding it to the 
atmosphere. But the great alterations effected in 
the appearance of our country by such extensive 
plantations and culture of various kinds of vegetable 
produce, influence not only indirectly our Fauna 
through the medium of climate, but also act directly 
on animals by accommodating a larger number 
than could otherwise find subsistence with us. This 
adoption of new residences by animals is a fact so 
generally allowed that I need not here insist on it. 
I have stated that equability and mildness of 
climate influence our Fauna; but does humidity 
also? I am not aware that it does. The two prin- 
cipal seasons in which our Fauna is rendered 
