Round-headed trees compose by far the largest of these divisions. The term includes all those trees which have an irregular surface in their boughs, more or less varied in outline, but exhibiting in the whole a top or head comparatively round; as the oak, ash, beech, and walnut. They are generally beautiful when young, from their smoothness, and the elegance of their forms; but often grow picturesque when age and time have had an opportunity to produce their wonted effects upon them. In general, however, the different round-headed trees may be considered as the most appropriate for introduction in highly-cultivated scenery, or landscapes where the character is that of graceful or polished beauty; as they harmonize with almost all scenes, buildings, and natural or artificial objects, uniting well with other forms and doing violence to no expression of scenery. From the numerous breaks in the surface of their foliage, which reflect differently the lights and produce deep shadows, there is great intricacy and variety in the heads of many round-topped trees; and therefore, as an outer surface to meet the eye in a plantation, they are much softer and more pleasing than the unbroken line exhibited by the sides of oblong or spiry-topped trees. The sky outline also, or the upper part of the head, varies greatly in round-topped trees from the irregularity in the disposition of the upper branches in different species, as the oak and ash, or even between individual specimens of the same kind of tree, as the oak, of which we rarely see two trees alike in form and outline, although they have the same characteristic expression; while on the other hand no two verdant objects can bear a greater general resemblance to each other and show more sameness of figure than two Lombardy poplars. "In a tree," says Uvedale Price, "of which the foliage is everywhere full and unbroken, there can be but little variety of form; then, as the sun strikes only on the surface, neither can there be much variety of light and shade; and as the apparent color of objects changes according to the different degrees of light or shade in which they are placed, there can be as little variety of tint; and lastly, as there are none of these openings that excite and nourish curiosity, but the eye is everywhere opposed by one uniform leafy screen, there can be as little intricacy as variety." From these remarks, it will be perceived that even among round-headed trees there may be great difference in the comparative beauty of different sorts; and judging from the excellent standard here laid down, it will also be seen how much in the eye of a painter a tree with a beautifully diversified surface, as the oak, surpasses in the composition of a scene one with a very regular and compact surface and outline, as the horse-chestnut. In planting large masses of wood, therefore, or even in forming large groups in park scenery, round-headed trees of the ordinary loose and varied manner of growth common in the majority of forest trees, are greatly to be preferred to all others. When they cover large tracts, as several acres, they convey an emotion of grandeur to the mind; when they form vast forests of thousands of acres, they produce a feeling of sublimity; in the landscape garden when they stand alone, or in fine groups, they are graceful or beautiful. While young they have an elegant appearance; when old they generally become majestic or picturesque. Other trees may suit scenery or scenes of particular and decided characters, but round-headed trees are decidedly the chief adornment of general landscape.