The mean annual temperature of the European countries on the southern slope of the mountain axis is from 60° to 70° 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 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;]