HORSE-ISLAND, an island, in the parish of SKULL, Western Division of the barony of WEST-CARBERY, county of CORK, and province of MUNSTER, 3 miles (S.) from Ballydehob; containing 81 inhabitants. It is situated in Roaring-Water bay, about a mile from the main land, and comprises 92 acres, based on clay-slate, with a very uneven surface, which is principally under cultivation by the spade. Here are copper mines which yield very pure ore; they were partially worked by Lord Audley, the proprietor of the island, and by the Irish Mining Company, and have been extensively worked by the West Cork Mining Company, which commenced operations in 1835, and soon discovered a large body of excellent ore close to the eastern point of the island, which is sold at Swansea at a high price. About 100 miners are employed, for whom several houses have been erected.