BOYNE, a river of Ireland, which rising in the Bog of Allen, near Carbery in Kildare, and flowing in a N.E. direction, passes Trim, Navan,and Drogheda, and enters the Irish Sea, about four miles below the last-mentioned town. It is navigable for barges of 70 tons to Navan, 19 miles from its mouth. About a mile west of Drogheda, an obelisk, 150 feet in height, marks the spot where the forces of William III. gained the celebrated victory over those of James II., on 1st July 1690, known as the “battle of the Boyne.”