I Will Not Enter Upon The Great Question, Whether In The Sahara, That Mediterranean Of Moving Sands, The Germs Of Organic Life Are Increased In Our Days.

In proportion as our geographical knowledge has extended we have discovered in the eastern part of the desert islets

Of verdure; oases covered with date-trees crowd together in more numerous archipelagos, and open their ports to the caravans; but we are ignorant whether the form of the oases have not remained constantly the same since the time of Herodotus. Our annals are too incomplete to enable us to follow Nature in her slow and gradual progress. From these spaces entirely bare whence some violent catastrophe has swept away the vegetable covering and the mould; from those deserts of Syria and Africa which, by their petrified wood, attest the changes they have undergone; let us turn to the grass-covered Llanos and to the consideration of phenomena that come nearer the circle of our daily observations. Respecting the possibility of a more general cultivation of the steppes of America, the colonists settled there, concur in the opinions I have deduced from the climatic action of these steppes considered as surfaces, or continuous masses. They have observed that downs enclosed within cultivated and wooded land sooner yield to the labours of the husbandman than soils alike circumscribed, but forming part of a vast surface of the same nature. This observation is extremely just whether in reference to soil covered with heath, as in the north of Europe; with cistuses, mastic-trees, or palmettos, as in Spain; or with cactuses, argemones, or brathys, as in equinoctial America.

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