In Herefordshire, especially on the northern and eastern sides, Oak timber abounds; and in many of the woods it is usual to have felling at periods varying from sixteen to twenty years; the straightest and handsomest are left for timber, or, as it is called, groved; and they are from time to time thinned, and a regular distance kept between them. The effect produced on these groved trees is, that from being exposed to air and sun, the rapidity of their growth is increased in bulk, height, and quality; and in sixty or eighty years they become valuable timber.