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Pond Island Light
Pond Island Light is a lighthouse at the mouth of the Kennebec River The Kennebec River (Abenaki language, Abenaki: ''Kinəpékʷihtəkʷ'') is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map , accessed June 30, 2011 river within the U.S. state of Maine. It ri ..., Maine. It was first established in 1821 on Pond Island (one of several in Maine) at the mouth of the Kennebec. The present structure was built in 1855. References Lighthouses completed in 1855 Lighthouses in Sagadahoc County, Maine 1821 establishments in Maine {{US-lighthouse-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kennebec River
The Kennebec River (Abenaki: ''Kinəpékʷihtəkʷ'') is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map , accessed June 30, 2011 river within the U.S. state of Maine. It rises in Moosehead Lake in west-central Maine. The East and West Outlets join at Indian Pond and the river flows southward. Harris Station Dam, the largest hydroelectric dam in the state, was constructed near that confluence. The river is joined at The Forks by its tributary the Dead River, also called the West Branch. It continues south past the cities of Madison, Skowhegan, Waterville, and the state capital Augusta. At Richmond, it flows into Merrymeeting Bay, a freshwater tidal bay into which also flow the Androscoggin River and five smaller rivers. The Kennebec runs past the shipbuilding center of Bath, and has its mouth at the Gulf of Maine in the Atlantic Ocean. The Southern Kennebec flows below the fall line and does not have rapids. As a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fresnel Lens
A Fresnel lens ( ; ; or ) is a type of composite compact lens developed by the French physicist Augustin-Jean Fresnel (1788–1827) for use in lighthouses. It has been called "the invention that saved a million ships." 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. A Fresnel lens can be made much thinner than a comparable conventional lens, in some cases taking the form of a flat sheet. The simpler dioptric (purely refractive) form of the lens was first proposed by Count Buffon and independently reinvented by Fresnel. The '' catadioptric'' form of the lens, entirely invented by Fresnel, has outer elements that use total internal reflection as well as refraction; it can capture more oblique light from a light source and add it to the beam of a lighthouse, making the light visible from greater distances. Description The Fresnel len ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pond Island Light Maine With Seguin 2009
A pond is an area filled with water, either natural or artificial, that is smaller than a lake. Defining them to be less than in area, less than deep, and with less than 30% emergent vegetation helps in distinguishing their ecology from that of lakes and wetlands.Clegg, J. (1986). Observer's Book of Pond Life. Frederick Warne, London Ponds can be created by a wide variety of natural processes (e.g. on floodplains as cutoff river channels, by glacial processes, by peatland formation, in coastal dune systems, by beavers), or they can simply be isolated depressions (such as a kettle hole, vernal pool, prairie pothole, or simply natural undulations in undrained land) filled by runoff, groundwater, or precipitation, or all three of these. They can be further divided into four zones: vegetation zone, open water, bottom mud and surface film. The size and depth of ponds often varies greatly with the time of year; many ponds are produced by spring flooding from rivers. Ponds may be f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lighthouse
A lighthouse is a tower, building, or other type of physical structure designed to emit light from a system of lamps and lens (optics), lenses and to serve as a beacon for navigational aid, for maritime pilots at sea or on inland waterways. Lighthouses mark dangerous coastlines, hazardous shoals, reefs, rocks, and safe entries to harbors; they also assist in aerial navigation. Once widely used, the number of operational lighthouses has declined due to the expense of maintenance and has become uneconomical since the advent of much cheaper, more sophisticated and effective electronic navigational systems. History Ancient lighthouses Before the development of clearly defined ports, mariners were guided by fires built on hilltops. Since elevating the fire would improve the visibility, placing the fire on a platform became a practice that led to the development of the lighthouse. In antiquity, the lighthouse functioned more as an entrance marker to ports than as a warning signa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lighthouses Completed In 1855
A lighthouse is a tower, building, or other type of physical structure designed to emit light from a system of lamps and lenses and to serve as a beacon for navigational aid, for maritime pilots at sea or on inland waterways. Lighthouses mark dangerous coastlines, hazardous shoals, reefs, rocks, and safe entries to harbors; they also assist in aerial navigation. Once widely used, the number of operational lighthouses has declined due to the expense of maintenance and has become uneconomical since the advent of much cheaper, more sophisticated and effective electronic navigational systems. History Ancient lighthouses Before the development of clearly defined ports, mariners were guided by fires built on hilltops. Since elevating the fire would improve the visibility, placing the fire on a platform became a practice that led to the development of the lighthouse. In antiquity, the lighthouse functioned more as an entrance marker to ports than as a warning signal for reefs and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
