The method of Palissy, though, as I have said, similar in principle to that of Babinet, would be cheaper of execution, and, at the same time, more efficient. He proposes the construction of relatively small filtering receptacles, into which he would conduct the rain falling upon a large area of rocky hillside, or other sloping ground not readily absorbing water. This process would, in all probability, be a very successful, as well as an inexpensive, mode of economizing atmospheric precipitation, and compelling the rain and snow to form perennial fountains at will.
Economizing Precipitation.
The methods suggested by Palissy and by Babinet are of limited application, and designed only to supply a sufficient quantity of water for the domestic use of small villages or large private establishments. Dumas has proposed a much more extensive system for collecting and retaining the whole precipitation in considerable valleys, and storing it in reservoirs, whence it is to be drawn for household and mechanical purposes, for irrigation, and, in short, for all the uses to which the water of natural springs and brooks is applicable. His plan consists in draining both surface and subsoil, by means of conduits differing in construction according to local circumstances, but in the main not unlike those employed in improved agriculture, collecting the water in a central channel, securing its proper filterage, checking its too rapid flow by barriers at convenient points, and finally receiving the whole in spacious covered reservoirs, from which it may be discharged in a constant flow or at intervals as convenience may dictate.[408]
There is no reasonable doubt that a very wide employment of these various contrivances for economizing and supplying water is practicable, and the expediency of resorting to them is almost purely an economical question. There appears to be no serious reason to apprehend collateral evils from them, and in fact all of them, except artesian wells, are simply indirect methods of returning to the original arrangements of nature, or, in other words, of restoring the fluid circulation of the globe; for when the earth was covered with the forest, perennial springs gushed from the foot of every hill, brooks flowed down the bed of every valley. The partial recovery of the fountains and rivulets which once abundantly watered the face of the agricultural world seems practicable by such means, even without any general replanting of the forests; and the cost of one year's warfare, if judiciously expended in a combination of both methods of improvement, would secure, to almost every country that man has exhausted, an amelioration of climate, a renovated fertility of soil, and a general physical improvement, which might almost be characterized as a new creation.
CHAPTER V
THE SANDS.
ORIGIN OF SAND—SAND NOW CARRIED DOWN TO THE SEA—THE SANDS OF EGYPT AND THE ADJACENT DESERT——THE SUEZ CANAL——THE SANDS OF EGYPT—COAST DUNES AND SAND PLAINS—SAND BANKS—DUNES ON COAST OF AMERICA—DUNES OF WESTERN EUROPE—FORMATION OF DUNES—CHARACTER OF DUNE SAND—INTERIOR STRUCTURE OF DUNES—FORM OF DUNES—GEOLOGICAL IMPORTANCE OF DUNES—INLAND DUNES—AGE, CHARACTER, AND PERMANENCE OF DUNES—USE OF DUNES AS BARRIER AGAINST THE SEA—ENCROACHMENTS OF THE SEA—THE LIIMFJORD—ENCROACHMENTS OF THE SEA—DRIFTING OF DUNE SANDS—DUNES OF GASCONY—DUNES OF DENMARK—DUNES OF PRUSSIA—ARTIFICIAL FORMATION OF DUNES—TREES SUITABLE FOR DUNE PLANTATIONS—EXTENT OF DUNES IN EUROPE—DUNE VINEYARDS OF CAPE BRETON—REMOVAL OF DUNES—INLAND SAND PLAINS—THE LANDES OF GASCONY—THE BELGIAN CAMPINE—SANDS AND STEPPES OF EASTERN EUROPE—ADVANTAGES OF RECLAIMING DUNES—GOVERNMENT WORKS OF IMPROVEMENT.