and their relative situation: 7, the geological nature of the soil: 8,
the degree of cultivation, and of population, at which a country has
arrived: 9, the prevalent winds.

_Why are the strata of air upon all mountains of successive coldness?_

Because the air does not acquire immediately, by the passage of the
solar rays, a considerable degree of heat. Thus, with the elevation of
land, cold may be said to increase in very rapid progression. Winter
continues to reign on the Alps and the Pyrenees, while the flowers of
spring are covering the plains of northern France. This beneficent
appointment of Nature considerably increases the number of habitable
countries in the torrid zone. It is probable, that at the back of the
flat burning coasts of Guinea, there exist in the centre of Africa,
countries which enjoy a delightful temperature; as we see the vernal
valley of Quito, situate under the same latitude with the destructive
coasts of French Guyana, where the humid heat constantly cherishes the
seeds of disease. On the other hand, it is the continued elevation
of the ground, which, in the central parts of Asia, extends the cold
region to the 35th parallel of latitude, so that in ascending from
Bengal to Thibet, we imagine ourselves in a few days transported from
the equator to the pole.--_Maltebrun._

_Why does the destruction of forests sometimes prove beneficial to a
country?_

Because a freer circulation of air is thus procured--but carried too
far, it becomes a scourge which may desolate whole regions. We have
a sad example of this in the Cape de Verde islands, not to mention
others. It is the destruction of forests, and not a supposed cooling