Glossary - Part L

•  Lamp: The lighting apparatus inside the lens. (ie. oil lamp, kerosene vapor burner, electric light bulb).

•  Lantern: A room surrounded by windows which housed the lighthouse lens.

•  Leading Light: A lighthouse used as a landmark when fixing a course along a waterway. More commonly found as inland lights.

•  Lens: Glass optical system used to concentrate the light in a desired direction.

•  Lens Access Panel: A hinged panel or door that provides access to the inside of the lens for maintenance or inspection purposes.

•  Lens Bag: A Linen bag placed over the lens during the daylight hours by the keeper to prevent sunlight entering the lens and lighting the burner.

•  Lens Bottom Ring – A circular metal frame member that serves as a base for the lens assembly and also ties all the lower ends of the vertical frame members together in a fixed position.

•  Lens Frame: The Lens Frame is the metal structure that supports the various glass elements of the lens assembly in fixed positions.

•  Lens Panel: A Lens Panel is a section of a lens assembly that can be removed and replaced without disturbing the remainder of the assembly.

•  Lens Rollers (sometimes called Chariot Wheels): A set of wheels or rollers, which support a lens assembly and allow it to rotate around a central, vertical, axis.

•  Lens Screen: In a rotating optic apparatus a shield extending out from the lens frame to separate one lens panel from its neighbor.

•  Lens Top Ring: A circular metal frame member, at the top of the lens assembly that secures the vertical frame members in their correct position in the assembly.

•  Lewis Lamp: A variety of light that used a silvered copper reflector behind a glass lens. The design of the Lewis Lamp was heavily "borrowed" from that of the Argand Reflector, and was named for Winslow Lewis who imported the design from Europe.

•  Lighthouse: Enclosed tower originally designed with an enclosed lantern and built by a governing authority as an aid to navigation.

•  Lighthouse Board: A nine member board appointed by the US Congress in 1852, established to manage the lighthouses throughout the United States.

•  Light Station: Light tower and associated buildings (dwellings, sheds, boathouses, fog alarm, etc.) and the land they occupy.

•  Lightship: A vessel that acts as a lighthouse anchored off shore at a location unsuitable for a lighthouse.

•  Litharge: A type of putty, made from whiting, lead oxide and linseed oil, used to hold the glass elements in the frame of the lens assembly.

•  Lower Catadioptric Prisms: Glass lens elements located below the dioptric sections of the lens assembly.