The Pharohs of Alexandria, one of the Seven Wonders of the World, was the first lighthouse for which there remains a detailed account. Lighthouses are designed to provide ships with a navigational point of reference by day and night, as well as to indicate dangerous rocks or shoals. By the end of the 18th century, improvements began to be seen in the wood, coal, and oil illuminants. Electric carbon-arc lamps were in use as early as 1858. Arthur Kitson introduced in 1901 a lantern utilizing vaporized kerosene under pressure. The incandescent lamp came into use in the 1920s and now is standard lighting equipment.
Along with the development of lighting systems came improvements in optical systems. In 1890 a method was invented for rotating lights by floating the apparatus in a bath of mercury. Lighthouses are painted in distinctive patters for identification in daylight. Advances in the automation of electronic equipment have made it possible to maintain beacons from onshore. By the end of the 1980s, the last of the U.S. manned lighthouses, the Ambrose Beacon in New York harbor and several along the Maine coast, had been automated completely.