Spectacle Island Range Lights
Encyclopedia
Leading lights
Leading lights are a pair of light beacons, used in navigation to indicate a safe passage for vessels entering a shallow or dangerous channel; and may also be used for position fixing. At night, the lights are a form of leading line that can be used for safe navigation...
on Spectacle Island in Boston Harbor. They were established in 1897 and discontinued in 1913 after changes in the entrance channels to the harbor made them obsolete.