Glossary - Part P

•  Parabolic Reflector: A bowl-like metal device shaped to the parabolic curve, silver-plated, reflector with a small oil lamp in the center.

•  Paraffin Vapor Burner (PVB): Also known as petroleum vapor burner. A burner designed in the late 1890s that used preheated and pressurized kerosene (paraffin) and a mantle which created a brighter light than ordinary oil lamps.

•  Parapet: A walkway with railings, which encircled the lamp room.

•  Passing Light: A low intensity light which may be mounted on the structure of another light to enable the mariner to keep the latter light in sight when passing out of its beam during transit.

•  Pedestal: The structure upon which the lens apparatus, or a lamp changer within the lens, is mounted.

•  Pepper Pot/Salt Shaker: A popular term for the smaller square tapered style of Lighthouse. Roughly resembling the proportions of a salt or peppershaker, hence the term.

•  Period: The interval of time between the commencement of two identical successive cycles of the characteristic of the light or sound signal.

•  Pharologist: One who studies or is interested in lighthouses.

•  Pressed Glass: Glass formed into the shape required for optical purposes by allowing it to solidify from the molten state, under pressure, in a suitably shaped mold. Most small drum lenses are made in this manner.

•  Prism: A transparent piece of glass that refracts or disperses light.

•  Private Aid to Navigation: A navigation light that is privately owned and maintained. Sometime they are deactivated beacons that have been reactivated for historic purpose.