AGNES, St., one of the Scilly Islands, on the coast of Cornwall. The soil is fertile, and tolerably cultivated; but there is a great deficiency of water. A lighthouse on the island, about 50 feet in height, built on one of the loftiest hills, is an important object to seamen. Its exact position, as ascertained by the great trigonometrical survey, is in Long. 6. 19. 23. W. and Lat. 49. 53. 38. N. from Greenwich. The light is composed of Argand lamps, with reflectors, moving in a circular revolution, and presenting a bright and conspicuous light in every direction once a minute. Westward of St. Agnes is the Gillstone rock, on which Sir Cloudesley Shovel was lost in the Association ship of war in 1707.