I am a light, set to guide and warn mariners. I exhibit two steady and conspicuous li

I am a light, set to guide and warn mariners. I exhibit two steady and conspicuous lights, which can never be mistaken for any other, and am consequently an infallible mark to prevent ships from running foul of one another, in dark and dangerous nights. I am placed, by authority, at certain intervals, round the coast; and I am a perpetual beacon, to warn and direct vessels into the proper channels, and over the safe parts of the sea-marks. I am a