nteriorly, or from one of its parts to another. Still more,
its sea-line is so broken, it has so many intrusive gulfs and bays,
that, its surface considered, its maritime coast is greater than that of
any other continent. In this respect it contrasts strikingly with
Africa. Europe has one mile of coast-line for every 156 square miles of
surface, Africa has only one for every 623. This extensive maritime
contact adds, of course, greatly to its interior as well as exterior
accessibility.

[Sidenote: Distribution of heat in Europe.]

The mean annual temperature of the European countries on the southern
slope of the mountain axis is from 60 deg. to 70 deg. F., but of those to
the north the heat gradually declines, until, at the extreme limit on the
shores of Zembla, the ground is perpetually frozen. As on other parts of
the globe, the climate does not correspond to the latitude, but is
disturbed by several causes, among which may be distinguished the great
Atlantic current--the Gulf Stream coming from America--and the Sahara
Desert. The latter gives to the south of Europe an unduly high heat, and
the former to Ireland, England, and the entire west a genial
temperature. Together they press into higher latitudes the annual
isothermal lines. If in Europe there are no deserts, there are none of
those impenetrable forests seen in tropical countries. From the westerly
shores of Portugal, France, and Ireland, the humidity diminishes as we
pass to the east, and, indeed, if we advance into Asia, it disappears in
the desert of Gobi. There are no vast homogeneous areas as in Asia, and
therefore there is no widespread uniformity in the races of men.

[Sidenote: And the quantity of rain.]

But not only is the temperature of the European continent elevated by
the Gulf Stream and the south-west wind, its luxuriance of vegetation
depends on them; for luxuriance of vegetation is determined, among other
things, by the supply of rain. A profusion of water gives to South
America its amazing forests; a want inflicts on Australia its shadeless
trees, with their shrunken and pointed leaves. With the diminished
moisture the green gardens of France are replaced in Gobi by ligneous
plants covered with a gray down. Physical circumstances control the
vegetable as well as the animal world.

The westerly regions of Europe, through the influence of the south-west
wind, the Gulf Stream, and their mountain ranges, are supplied with
abundant rains, and