There is another effort of the French which may be watched with more anxiety and more comprehension by northern men than their admirable roads or their railways or their wires above the sand, and that is their afforestation. It is a debate which will not be decided (for the material of full decision is lacking) whether, since the Romans crowded their millions into this Africa, the rainfall has or has not changed. It is certain that they husbanded water upon every side and built great barricades to hold the streams; yet it is certain, also, that their cities stood where no such great groups of men could live to-day. There are those who believe that under Atlas, towards the desert, a shallow sea spread westward from the Mediterranean and from Syrtis: there are others who believe that the dry water-courses of the Sahara were recently alive with streams, and that the tombs and inscriptions of the waste places, now half buried in the sand, prove a great lake upon whose shores a whole province could cultivate and live. Both hypotheses are doubtful for this reason—that no good legend preserves the record. Changes far less momentous have left whole cycles of ballads and stories behind them. The Sahara has been the Sahara since men have sung or spoken of it. Moreover, the Romans did certainly push out, as the French have done, towards certain limits, beyond which no effort was worth the while of armies. They felt a boundary to the south. They could bear the summer of Biskra, but not that of Touggourt: their posts upon the edge of the desert were ultimate posts as are the European garrisons to-day. But in one thing the sense of change is justified, and that is the fall of the woods. Here Islam worked itself out fully: its ignorance of consequence, its absolute and insufficient assertion, its lack of harmony with the process and modulation of time, its Arabian origin, are all apparent in the destruction of trees. If the rainfall is as abundant as ever, it is not held, for the roots of trees are lacking, and if it be true that trees in summer bring rain of themselves by their leaves, then that benefit is also gone. There are many deep channels, called _secchias_, traversing the soft dust of the uplands, with no trace of bridges where the Roman roads cross them: they are new. They are carved by the sudden spates that follow the cloudbursts in the hills. Here, perhaps, in the Roman time were regular and even streams, and perhaps, upon their banks, where now are stretches of ugly earth quite bare, the legionaries saw meadows. At any rate, the trees have gone.