The paulownia, which thrives in Northern Italy, has a wood of little value, but the tree would serve well as a shelter for seedlings and young plants of more valuable species, and in other cases where a temporary shade is urgently needed. The young shoots, from a stem polled the previous season, almost surpass even the eucalyptus in rapidity of growth. Such a shoot from a tree not six inches in diameter, which I had an opportunity of daily observing, from the bursting out of the bud from the bark of the parent stem in April till November of the same year, acquired in that interval a diameter of between four and five inches and a height of above twenty feet.] which, latter, it is said, has a growth at least five, and, according to some, ten times more rapid than that of the oak—would prove good investments even in an economical aspect. [Footnote: The economical statistics of Grigor, Arboriculture, Edinburgh, 1868, are very encouraging. In the preface to that work the author says: "Having formed several large plantations nearly forty years ago, which are still standing, in the Highlands of Scotland, I can refer to them as, after paying every expense, yielding a revenue equal to that of the finest arable land in the country, where the ground previously to these formations was not worth a shilling an acre." See also Hartig, Ueber den Wachsthumsgang und Ertrag der Buche, Eiche und Kiefer, 1869, and especially Bryant, Forest Trees, chap. ix.]
There is no doubt that they would pay the expenses of their planting at no distant period, at least in every case where irrigation is possible, and in very many situations, terraces, ditches, or even horizontal furrows upon the hillsides, would answer as a substitute for more artificial irrigation. Large proprietors would receive important indirect benefits from the shelter and the moisture which forests furnish for the lands in their neighborhood, and eventually from the accumulation of vegetable mould in the woods. [Footnote: The fertility of newly cleared land is by no means due entirely to the accumulation of decayed vegetable matter on its surface, and to the decomposition of the mineral constituents of the soil by the gases emitted by the fallen leaves. Sachs has shown that the roots of living plants exercise a most powerful solvent action on rocks, and hence stones are disintegrated and resolved into elements of vegetable nutrition, by the chemical agency of the forest, more rapidly than by frost, rain, and other meteorological influences.] The security of the investment, as in the case of all real-estate, is a strong argument for undertaking such plantations, and a moderate amount of government patronage and encouragement would be sufficient to render the creation of new forests an object of private interest as well as of public advantage, especially in a country where the necessity is so urgent and the climate so favorable as in the United States.
Instability of American Life.
All human institutions, associate arrangements, modes of life, have their characteristic imperfections. The natural, perhaps the necessary defect of ours, is their instability, their want of fixedness, not in form only, but even in spirit. The face of physical nature in the United States shares this incessant fluctuation, and the landscape is as variable as the habits of the population. It is time for some abatement in the restless love of change which characterizes us, and makes us almost a nomade rather than a sedentary people. [Footnote: It is rare that a middle-aged American dies in the house where he was born, or an old man even in that which he has built; and this is scarcely less true of the rural districts, where every man owns his habitation, than of the city, where the majority live hired houses. This life of incessant flitting is unfavorable for the execution of permanent improvements of every sort, and especially of those which, like the forest, are slow in repaying any part of the capital expended in them. It requires a very generous spirit in a landholder to plant a wood on a farm he expects to sell, or which he knows will pass out of the hands of his descendants at his death. But the very fact of having begun a plantation would attach the proprietor more strongly to the soil for which he had made such a sacrifice; and the paternal acres would have a greater value in the eyes of a succeeding generation, if thus improved and beautified by the labors of those from whom they were inherited. Landed property, therefore, the transfer of which is happily free from every legal impediment or restriction in the United States, would find, in the feelings thus prompted, a moral check against a too frequent change of owners, and would tend to remain long enough in one proprietor or one family to admit of gradual improvements which would increase its value both to the possessor and to the state.] We have now felled forest enough everywhere, in many districts far too much. Let us restore this one element of material life to its normal proportions, and devise means of maintaining the permanence of its relations to the fields, the meadows, and the pastures, to the rain and the dews of heaven, to the springs and rivulets with which it waters the earth. The establishment of an approximately fixed ratio between the two most broadly characterized distinctions of rural surface—woodland and ploughland—would involve a certain persistence of character in all the branches of industry, all the occupations and habits of life, which depend upon or are immediately connected with either, without implying a rigidity that should exclude flexibility of accommodation to the many changes of external circumstance which human wisdom can neither prevent nor foresee, and would thus help us to become, more emphatically, a well-ordered and stable commonwealth, and, not less conspicuously, a people of progress.
CHAPTER IV.
THE WATERS.
Land Artificially won from the Waters—Great Works of Material
Improvement—Draining of Lincolnshire Fens—Incursions of the Sea in the
Netherlands—Origin of Sea-dikes—Gain and Loss of Land in the
Netherlands—Marine Deposits on the Coast of Netherlands—Draining of
Lake of Haarlem—Draining of the Zuiderzee—Geographical Effects of
Improvements in the Netherlands—Ancient Hydraulic Works—Draining of
Lake Celano by Prince Torlonia—Incidental Consequences of draining
Lakes—Draining of Marshes—Agricultural Draining—Meteorological
Effects of Draining—Geographical Effects of Draining—Geographical
Effects of Aqueducts and Canals—Antiquity of Irrigation—Irrigation in
Palestine, India, and Egypt—Irrigation in Europe—Meteorological
Effects of Irrigation—Water withdrawn from Rivers for
Irrigation—Injurious Effects of Rice-culture—Salts Deposited by Water
of Irrigation—Subterranean Waters—Artesian Wells—Artificial
Springs—Economizing Precipitation—Inundations in France—Basins of
Reception—Diversion of Rivers—Glacier Lakes—River Embankments—Other
Remedies against Inundations—Dikes of the Nile—Deposits of Tuscan
Rivers—Improvements in Tuscan Maremma—Improvements in Val di
Chiana—Coast of the Netherlands.
Land artificially won from the Waters.
Man, as we have seen, has done much to revolutionize the solid surface of the globe, and to change the distribution and proportions, if not the essential character, of the organisms which inhabit the land and even the waters. Besides the influence thus exerted upon the life which peoples the sea, his action upon the land has involved a certain amount of indirect encroachment upon the territorial jurisdiction of the ocean. So far as he has increased the erosion of running waters by the destruction of the forest or by other operations which lessen the cohesion of the soil, he has promoted the deposit of solid matter in the sea, thus reducing the depth of marine estuaries, advancing the coast-line, and diminishing the area covered by the waters. He has gone beyond this, and invaded the realm of the ocean by constructing within its borders wharves, piers, light-houses, breakwaters, fortresses, and other facilities for his commercial and military operations; and in some countries he has permanently rescued from tidal overflow, and even from the very bed of the deep, tracts of ground extensive enough to constitute valuable additions to his agricultural domain. The quantity of soil gained from the sea by these different modes of acquisition is, indeed, too inconsiderable to form an appreciable element in the comparison of the general proportion between the two great forms of terrestrial surface, land and water; but the results of such operations, considered in their physical and their moral bearings, are sufficiently important to entitle them to special notice in every comprehensive view of the relations between man and nature.
There are cases, as on the western shores of the Baltic, where, in consequence of the secular elevation of the coast, the sea appears to be retiring; others, where, from the slow sinking of the land, it seems to be advancing. These movements depend upon geological causes wholly out of our reach, and man can neither advance nor retard them. [Footnote: It is possible that the weight of the sediment let fall at the mouths of great rivers, like the Ganges, the Mississippi, and the Po, may cause the depression of the strata on which they are deposited, and hence if man promotes the erosion and transport of earthy material by rivers, he augments the weight of the sediment they convey into their estuaries, and consequently his action tends to accelerate such depression. There are, however, cases where, in spite of great deposits of sediment by rivers, the coast is rising. Further, the manifestation of the internal heat of the earth at any given point is conditioned by the thickness of the crust at such point. The deposits of rivers tend to augment that thickness at their estuaries. The sediment of slowly-flowing rivers emptying into shallow seas is spread over so great a surface that we can hardly imagine the foot or two of slime they let fall over a wide area in a century to form an element among even the infinitesimal quantities which compose the terms of the equations of nature. But some swift rivers, rolling mountains of fine earth, discharge themselves into deeply scooped gulfs or bays, and in such cases the deposit amounts, in the course of a few years, to a mass the transfer of which from the surface of a large basin, and its accumulation at a single point, may be supposed to produce other effects than those measurable by the sounding-line. Now, almost all the operations of rural life, as I have abundantly shown, increase the liability of the soil to erosion by water. Hence, the clearing of the valley of the Ganges, for example, by man, must have much augmented the quantity of earth transported by that river to the sea, and of course have strengthened the effects, whatever they may be, of thickening the crust of the earth in the Bay of Bengal. In such cases, then, human action must rank among geological influences.