have a favourable mean annual temperature; but as we
pass to the eastern confines the number of rainy days diminishes, the
absolute annual quantity of rain and snow is less, and the mean annual
temperature is lower. On the Atlantic face of the mountains of Norway it
is perpetually raining: the annual depth of water is there 82 inches;
but on the opposite side of those mountains is only 21 inches. For
similar reasons, Ireland is moist and green, and in Cornwall the laurel
and camellia will bear a winter exposure.

There are six maximum points of rain--Norway, Scotland, South-western
Ireland and England, Portugal, North-eastern Spain, Lombardy. They
respectively correspond to mountains. In general, the amount of rain
diminishes from the equator toward the poles; but it is greatly
controlled by the disturbing influence of elevated ridges, which in many
instances far more than compensate for the effects of latitude. The Alps
exercise an influence over the meteorology of all Europe.

[Sidenote: The number of rainy days;]

Not only do mountains thus determine the absolute quantity of rain, they
also affect the number of rainy days in a year. The occurrence of a
rainy season depends on the amount of moisture existing in the air; and
hence its frequency is greater at the Atlantic sea-board than in the
interior, where the wind arrives in a drier state, much of its moisture
having been precipitated by the mountains forcing it to a great
elevation. Thus, on the eastern coast of Ireland it rains 208 days in a
year; in England, about 150; at Kazan, 90; and in Siberia only 60 days.

[Sidenote: and of snowy days.]

When the atmospheric temperature is sufficiently low, the condensed
water descends under the form of snow. In general, the annual depth of
snow and the number of snowy days increase toward the north. In Rome the
snowy days are 1-1/2; in Venice, 5-1/2; in Paris, 12; in St.
Petersburgh, 171. Whatever causes interfere with the distribution of
heat must influence the precipitation of snow; among such are the Gulf
Stream and local altitude. Hence, on the coast of Portugal, snow is of
infrequent occurrence; in Lisbon it never snowed from 1806 to 1811.

Such facts teach us how many meteorological contrasts Europe presents,
how many climates it contains. Necessarily it is full of modified men.

[Sidenote: Vibrations of the isothermal lines.]

If we examine the maps of monthly isothermals, we observe how strikingly
those li