THE INUNDATIONS IN FRANCE—CAUSE AND REMEDY.
1, Adam Street, ildelphi, 16th June 1856.
Sza—Engineering and other criticism on the late water calamities takes the form of speculation as to what should be done in providing sufficient embankments and outlets to carry off surplus water in times of emergency. There is deeper speculation than this as to the cause of the inundations, and there are certain facts that must enter into the consideration.
Time was, if report be correct, that the Rhone was a regular river in its habits, providing for navigation the year round, not subject to overflow, and certainly not to the extent observed at variors intervals of late years. The proof of this is the large number of buildings formed of sunburned bricks, which melt down like sugar-candy when soaked in water. It is clear that people would not have built such structures where they expected floods to reach them ; and thus we have evidence that floods reaoh to a greater height now than formerly. We know also that the Rhone is not a navigable river above three months in the year. We therefore cannot escape the conviction that some great change must have taken place of late years to convert a regular stream into an alternate food and shallow. The solution is not difficult to arrive at.
All great rivers must be supplied from one of two sources—the waters of evaporation converted into ram, or into snow. In a country of much rain the raver may be maintained in constant flow without great fountain-stores. In a country with a long dry season the regular river must be provided with natural fountain-stores for gradual overflow.
The sources of the Rhone are the hills and valleys of the Alps. In the olden time these were thickly wooded, and the pine forest sheltered the snow from the sun and prevented it from sliding down the slopes. Gradually melting, it supplied, but did not overflow the river the year round. Increase of population and scarcity of fuel have year after year denuded the mountains of timber. The snow descends, but has no shelter. It collects till change of temperature loosens it, and it rushes down in an universal tor- rent, to produce temporary destruction succeeded by a drought. Within a •
few years past several inundations have occurred at Lyons, and the last one the most mischievous. Future ones will probably exceed this. If France would maintain her noble Rhone and disable it for mischief, it is to the mountains of Switzerland that she must apply, not her engineering, but her planting faculties i restoring the pine forests that nature provided and man has destroyed. Better rent from the Swiss the Alpine forests and Lake Leman as snow and water storage, and pay them in coal of St. Etienne the fair value of the fuel, than go on suffering a perennial havoc, or only avoid- ing it by. digging out great trenches and piling up huge mounds,. to waste the precious source of fertility in the Mediterranean Sea. Switzerland, like France, trusts to timber for fuel ; and population in countries with winters is ever pressing against the means of artificial warmth ; and thus trees of all kinds, whether serving for ornament or utility, are destroyed. Only by the free diffusion of mineral fuel, or by lessen- ing the amount of population, can this evil be remedied. It behoves France to study the interests of Switzerland as well as her own, for she holds the keys of the water-supply; and, used rightly, that water-supply would be a source of wealth that would outvalue manyfold the fee simple of the Alpine forests. Tears back, a Swiss engineer built up a name by eonetructmg the famed slide of Alpnach, to facilitate the denudation of mountain forests. The economist will win greater fame who shall be the means of restoring the forests to their ancient boundaries, as valuable to France as are the artificial lakes called bunds to Eastern India. Every ternary possesses its own peculiar properties and aptitudes. The peculiar aptitude of Switzerland is that of a great water company for the supply of a large part of Europe in France, Germany, and Italy. Were it a possible thing for Switzerland to store up the whole of her water, suffering the sur- plus to flow away by some underground tunnel to the sea, she would become a practical part-owner of the fertile lands beyond her borders as a commuta- tion or rent-charge. As it is, she only possesses the power of ravaging those lands at intervals, unintentionally, through the mere poverty of fuel amongst her people. Switzerland is a necessity to Southern France, and on her well or ill being must depend much of the prosperity of Southern France. Only give the Swiss a greater inducement for the maintenance than for the de- struction of those forests, and the evil will be remedied. If the Third Napo- leon takes this wide view of the engineering question, he will unite the in- terests of France and Switzerland in a ,joint bond against poverty of fuel, either by tempting the Swiss to work in France, or by the transfer of mine- ral fuel as a burnt offering to save the forests.
Yours faithfully, W. BRIDGES ADAMS.
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