A lens lantern is a small, self-contained lamp structure which may sometimes be used to serve as a lighthouse

Lighthouse

A lighthouse is a tower, building, or other type of structure designed to emit light from a system of lamps and lenses or, in older times, from a fire, and used as an aid to navigation for maritime pilots at sea or on inland waterways....

. Unlike a regular Fresnel lens

Fresnel lens

A Fresnel lens is a type of lens originally developed by French physicist Augustin-Jean Fresnel for lighthouses.The design allows the construction of lenses of large aperture and short focal length without the mass and volume of material that would be required by a lens of conventional design...

, the lantern requires no housing to protect it from the weather; its glass sides would refract

Refraction

Refraction is the change in direction of a wave due to a change in its speed. It is essentially a surface phenomenon . The phenomenon is mainly in governance to the law of conservation of energy. The proper explanation would be that due to change of medium, the phase velocity of the wave is changed...

 and magnify the light in the same fashion as would the lens. Lens lanterns were popular alternatives to lighthouses in the nineteenth century; they required less care, were cheaper to erect, and could be fairly easily placed.

See also

• F. Ross Holland, Jr.
  F. Ross Holland, Jr.
  F Ross Holland, Jr. was an American historian. He is best remembered today for his books on American lighthouses.-Life:...
  
    America's Lighthouses: Their Illustrated History Since 1716.