That this is not wholly owing to the moisture and cold consequent to the moss formation, or to any cover or want of cover to the earth, of timber, or of any other plants which might possibly have effect upon the temperature by shade, evolution of vegetable heat, electric or meteoric agency, we think proved, should the asserted fact be correct, that, in the small _oes_ of Shetland, (so distant from any considerable portion of land as not to be under these influences, and so small, that the climate must be solely dependant upon the sea), timber is found in the morasses, although the climate will not now admit of timber growing, being apparently equally deteriorated as that of the Mainland. It is not improbable that the superior former climate of the North of Scotland and Islands was owing to their having formed, at one time, an extensive country, perhaps joined to the continent, and thus partaking of the continental climate, that is, having a colder winter and warmer summer, capable of producing considerable vigour of arboreous vegetation, and not so favourable to the generating of that fixed vegetable incubus, peat-moss, who has crept over, and folded {289} in her chill embrace, the once fair districts of northern Scotland. The fogs and more steady low temperature of insular situation, which now prevail, not only induce that chemical change in dead and dying vegetables which forms peat-moss, and preserves this moss from decay, but also being too cool for the vegetation of the gramineæ, &c. tend only to promote the general spread of sphagni and other moss-generating plants, which, again, are almost the only plants that can vegetate on acrid moss-flow, as they draw little or nothing from below, and are nourished directly by the moisture and other fluids of the atmosphere.