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used for a Vinery, and superior to that of most vineries. In the former, what is deficient in fineness is often compensated by variety, and by the extensive scope, which it gives to the roots to search for their food.

On considering these various methods of improving Soils, for the use of woody plants, the great, and, indeed, paramount importance of Subsoils, cannot fail to strike the reader. In fact, the latter may be said, in a great measure, to command and render subordinate the actual properties of the former, rendering them favourable or unfavourable, according to their own peculiar character. The first question that is asked by a skilful planter, in surveying a place for the first time, is not respecting the Soil, but the Subsoil. If that be propitious, he is comparatively indifferent as to the superincumbent strata. All soils are susceptible of melioration, from the most silicious, to the most argillaceous. Their pernicious ingredients can often be modified, if they cannot be altered, as we have already seen; but subsoils are the gift of nature, for evil or for good, and always lie beyond the reach of our improvement. In order that the reader may form a right judgment of both their favourable and unfavourable properties, for the growth of wood, the following short view is subjoined of the merits of both.

The most favourable subsoils are those, through

which the excess of water, received in rainy seasons, is allowed slowly to percolate, and which retain moisture sufficient for the sustenance of plants. First, close-lying strata; in which a considerable proportion of sand and fine gravel is intimately mixed. Secondly, free-stone; provided a bed of hard and impermeable clay does not intervene between it and the soil, which sometimes happens. And thirdly, a kind of greenstone (Scotticè, rotten whin), which is the most favourable of all, when there is over it a sufficient depth of mould, for the above purposes. Such, for example, are the soil and subsoil of that favourite tract of country, at the foot of the Ochill and other hills, in Stirlingshire and Perthshire, so well known for the growth of its timber. It descends, in a gradual slope, from the hills towards the river Forth, both east and west of the town of Stirling; while the river slowly winds through the rich, but alluvial plain below. In this sort of subsoil, the excess of the water collected from the sky, and the heights above, passes through the fissures, and is received and retained in its subterraneous cavities; by which means the rock, being always damp, and never exsiccated, can communicate its moisture to the soil above, in seasons of drought. It is true, this rock sends out frequent springs, from its internal reservoirs, to the surface: But they are often useful, instead of being pernicious; and they may generally be carried off,

by drains of inconsiderable depth, cut across the outcropping extremity of the rock.

The Subsoils of an unfavourable quality are, First, such as are composed of dense and argillaceous substances, through which no water can pass, it being retained stagnant at the bottom of the soil. In this situation, it has the most injurious effects, not only by chilling the roots that reach it, but by disabling the soil from exerting that repulsive force, which, as has been seen, is necessary to fertility. Secondly, Those open beds of loose stones and sand, from the bottom of which water is readily drawn off, by subterraneous outlets. These strata are sometimes continuous, but they oftener occur in narrow lines or strips; they are named "Scalds" by the Norfolk farmers, and are as injurious to crops in a wet, as in a dry season. Thirdly, There may be added those extensive ranges, or strata of dry rocks, of a hard texture, composed of slate, sometimes granite, but most commonly of gneiss, accompanied, in some districts, with a considerable proportion of iron, probably in the state of orange oxide. These rocks run in long ridges through the districts where they lie, sometimes narrow, and sometimes of a considerable breadth. They are dry to a great breadth, and full of fissures, through which the water quickly passes. The orange oxide always appears in thin lamina among the fissures. As they are, like the

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sandy bottoms, not retentive of water, all vegetation is destroyed in dry seasons, on the soils which cover them, and woods, were they planted there, would share the same fate. When these rocks are near the surface, the oxide, with which they abound, is generally injurious to vegetable life, and Trees die, as soon as their roots come in contact with it. Of these rocky strata, the greater part of the Western Highlands and Islands of Scotland furnish remarkable examples, excluding, of course, in most districts, the ingredient of iron. is from a want of Soil, and not of climate, that woods of any given extent cannot be got up in those unsheltered, but romantic regions.-Nature is everywhere impartial in her gifts. Where wood abounds, the character of a district is often tame and uninteresting. Were the grand scenery of these "high-featured countries," their sublime mountains, and blue lakes crowned with the forests of the south, they would, in point of picturesque beauty, be the paradise of the earth.

Happy, then, is the planter, who has none of these Dry Rocks for his subsoil; for it clearly appears, that no Planting, nor Removal of Trees, is possible, of whatever size, where they are present. Still happier is he, who, with clay and sand intermingled beneath his surface, or even with those untoward substances separately composing his soils, can, by industry and skill, prepare them for his pur

pose. But happiest, certainly, of all is the man, who can boast the possession of that enviable Greenstone or rotten Whin, with the deep, friable, and dark-coloured mould of the Ochills superincumbent on it; for then he may plant or remove whatever Trees he pleases, and without preparation, either chemical or mechanical.

In conclusion, I have to observe, that there is, perhaps, some reason to claim the indulgence of the general reader, for the seemingly elaborate manner, in which I have endeavoured to point out the chemical and scientific principles, on which soils should be improved, and rendered proper for the food of plants. It has been said above, and it cannot be too often repeated, or too earnestly enforced, that it is by principles drawn from Nature, and elucidated by Science, that any real progress can be made in an art like the one under discussion, where Nature and Science must unite in regulating the process, and art must follow in the track which they prescribe.

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