Complex sentence: The United States Coast Guard took over the Lightouse Service in 1939 and manned the station until 1973, when the lens was covered and a modern rotating beacon was mounted on a metal stand on the roof west of the lantern room.
Split into simpler sentences: The United States Coast Guard took over the Lightouse Service in 1939. The Coast Guard and manned the station until 1973, when the lens was covered and a modern rotating beacon was mounted on a metal stand on the roof west of the lantern room.