Trees in full foliage have long been noted as great attractors of humidity, and a young wych elm in full leaf affords a good example of this supposed power; but in the winter of the year, when trees are perfectly denuded, this faculty of creating moisture about them is equally obvious, though not so profusely. A strongly marked instance of this was witnessed by me, when ascending a hill in the month of March. The weather had previously been very fine and dry, and the road in a dusty state; but a fog coming on, an ash tree hanging over the road was dripping with water so copiously, that the road beneath was in a puddle, when the other parts continued dry, and manifested no appearance of humidity. That leaves imbibe moisture by one set of vessels and discharge them by another, is well-known; but these imbibings are never discharged in falling drops: the real mystery was, the fog in its progress was impeded by the boughs of the tree, and gradually collected on the exposed side of them, until it became drops of water, whereas the surrounding country had only a mist flying over it. Thus in fact the tree was no attractor, but a condenser; the gate of a field will in the same manner run down with water on the one side, and be dry on the other; as will a stick, or a post, from the same cause. It is upon this principle that currents of air will be found under trees in summer, when little is perceived in open places; and the under leaves and sprays will be curled and scorched at times, when the parts above are uninjured. The air in its passage being stopped and condensed against the foliage of the tree, it accordingly descends along its surface or front, and escapes at the bottom, where there are no branches or leaves to interrupt its progress. In winter there is little to impede the breeze in its course, and it passes through; consequently at this season the air under a tree is scarcely more sensibly felt than in the adjoining field. It may be observed, that in the spring of the year the herbage under trees is generally more vivid and luxuriant, than that which is beyond the spread of the branches: this may be occasioned, in some instances, by cattle having harbored there, and the ground becoming in consequence more manured; but it will be found likewise manifestly verdant and flourishing where no such accessory could have enriched it, and is, I apprehend, in general, chiefly owing to the effects of the driving fogs and mists, which cause a frequent drip beneath the tree, not experienced in other places, and thus in a manner keep up a perpetual irrigation and refreshment of the soil, and promote the decomposition of the foliage beneath, which being drawn into the earth by worms, contributes to the verdure by the nutriment they yield.