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Pungoteague Creek Light
The Pungoteague Creek Light was a small screwpile lighthouse constructed in the Chesapeake Bay in 1854. Destroyed in 1856, it had the shortest recorded existence of any lighthouse on the Bay, and possibly the United States, at just 459 days. The lighthouse was built just offshore from Accomack County, Virginia, and was located near the mouth of Pungoteague Creek, then called the Pungoteague River. It was the first screwpile lighthouse built on the Chesapeake, and its construction was overseen by Major Hartman Bache. Most of the foundation was prefabricated in Philadelphia, and was sent, along with the construction crew, down the Bay from Baltimore on April 23, 1854. It was originally estimated that construction of the light would take only six weeks, but lengthy calms during the voyage combined with the crew's inexperience and difficulty in sinking the piles extended the process to almost six months. The lighthouse was finished and commissioned on November 1, 1854. A small ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chesapeake Bay
The Chesapeake Bay ( ) is the largest estuary in the United States. The bay is located in the Mid-Atlantic (United States), Mid-Atlantic region and is primarily separated from the Atlantic Ocean by the Delmarva Peninsula, including parts of the Eastern Shore of Maryland, the Eastern Shore of Virginia, and the state of Delaware. The mouth of the bay at its southern point is located between Cape Henry and Cape Charles (headland), Cape Charles. With its northern portion in Maryland and the southern part in Virginia, the Chesapeake Bay is a very important feature for the ecology and economy of those two states, as well as others surrounding within its watershed. More than 150 major rivers and streams flow into the bay's drainage basin, which covers parts of six states (New York (state), New York, Pennsylvania, Delaware, Maryland, Virginia, and West Virginia) and all of Washington, D.C. The bay is approximately long from its northern headwaters in the Susquehanna River to its outlet i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fresnel Lens
A Fresnel lens ( ; ; or ) is a type of composite compact lens (optics), lens which reduces the amount of material required compared to a conventional lens by dividing the lens into a set of concentric annular sections. The simpler Dioptrics, dioptric (purely refraction, refractive) form of the lens was first proposed by Georges-Louis Leclerc, Comte de Buffon, and independently reinvented by the French physicist Augustin-Jean Fresnel (1788–1827) for use in lighthouses. The Catadioptric system, catadioptric (combining refraction and reflection) form of the lens, entirely invented by Fresnel, has outer Prism (optics), prismatic elements that use total internal reflection as well as refraction to capture more oblique light from the light source and add it to the beam, making it visible at greater distances. 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buildings And Structures In Accomack County, Virginia
A building or edifice is an enclosed structure with a roof, walls and windows, usually standing permanently in one place, such as a house or factory. Buildings come in a variety of sizes, shapes, and functions, and have been adapted throughout history for numerous factors, from building materials available, to weather conditions, land prices, ground conditions, specific uses, prestige, and aesthetic reasons. To better understand the concept, see ''Nonbuilding structure'' for contrast. Buildings serve several societal needs – occupancy, primarily as shelter from weather, security, living space, privacy, to store belongings, and to comfortably live and work. A building as a shelter represents a physical separation of the human habitat (a place of comfort and safety) from the ''outside'' (a place that may be harsh and harmful at times). buildings have been objects or canvasses of much artistic expression. In recent years, interest in sustainable planning and building practi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lighthouses In Virginia
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 the advent of much cheaper, more sophisticated, and more 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 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 promontories, unlike many moder ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Riprap
Riprap (in North American English), also known as rip rap, rip-rap, shot rock, rock armour (in British English) or rubble, is human-placed rock or other material used to protect shoreline structures against scour and water, wave, or ice erosion. Riprap is used to armor shorelines, streambeds, bridge abutments, foundational infrastructure supports and other shoreline structures against erosion. Common rock types used include granite and modular concrete blocks. Rubble from building and paving demolition is sometimes used, as well as specifically designed structures called ''tetrapods'' or similar concrete blocks. Riprap is also used underwater to cap immersed tubes sunken on the seabed to be joined into an undersea tunnel. Environmental effects Sediment effects Riprap causes morphological changes in the riverbeds they surround. One such change is the reduction of sediment settlement in the river channel, which can lead to scouring of the river bed as well as coarser sedime ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caisson (engineering)
In geotechnical engineering, a caisson (; borrowed , , an augmentative of ) is a watertight retaining structure. It is used, for example, to work on the foundation (architecture), foundations of a bridge pier (architecture), pier, for the construction of a concrete dam, or for the repair of ships. Caissons are constructed in such a way that the water can be pumped out, keeping the work environment dry. When piers are being built using an open caisson, and it is not practical to reach suitable soil, Deep foundation, friction pilings may be driven to form a suitable sub-foundation. These piles are connected by a foundation pad upon which the column pier is erected. Caisson engineering has been used since at least the 19th century, with three prominent examples being the Royal Albert Bridge (completed in 1859), the Eads Bridge (completed in 1874), and the Brooklyn Bridge (completed in 1883). Types To install a caisson in place, it is brought down through soft mud until a suitable ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Department Of The Treasury
The Department of the Treasury (USDT) is the Treasury, national treasury and finance department of the federal government of the United States. It is one of 15 current United States federal executive departments, U.S. government departments. The department oversees the Bureau of Engraving and Printing and the United States Mint, U.S. Mint, two federal agencies responsible for printing all paper currency and minting United States coinage, coins. The treasury executes Currency in circulation, currency circulation in the domestic fiscal system, Tax collector, collects all taxation in the United States, federal taxes through the Internal Revenue Service, manages United States Treasury security, U.S. government debt instruments, Bank regulation#Licensing and supervision, licenses and supervises banks and Savings and loan association, thrift institutions, and advises the Federal government of the United States#Legislative branch, legislative and Federal government of the United Stat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lighthouse Keeper
A lighthouse keeper or lightkeeper is a person responsible for tending and caring for a lighthouse, particularly the light and lens in the days when oil lamps and clockwork mechanisms were used. Lighthouse keepers were sometimes referred to as "wickies" because of their job trimming the wicks. Duties and functions Historically, lighthouse keepers were needed to trim the wicks, replenish fuel, wind clockworks and perform maintenance tasks such as cleaning lenses and windows. They were also responsible for the fog signal and the weather station, and played a major role in search and rescue at sea. Because most lighthouses are located in remote, isolated or inaccessible areas on islands and coastlines, it was typical for the work of lighthouse keeper to remain within a family, passing from parents to child, all of whom lived in or near the lighthouse itself. "Stag light" was an unofficial term given to some isolated lighthouses in the United States Lighthouse Service. It meant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drift Ice
Drift or Drifts may refer to: Geography * Drift or ford (crossing) of a river * Drift (navigation), difference between heading and course of a vessel * Drift, Kentucky, unincorporated community in the United States * In Cornwall, England: ** Drift, Cornwall, village ** Drift Reservoir, associated with the village Science, technology, and physics * Directional Recoil Identification from Tracks, a dark-matter experiment * Drift (video gaming), a typical game-controller malfunction * Drift pin, metalworking tool for localizing hammer blows and for aligning holes * Drift (geology), deposited material of glacial origin * drift (in mining), a roughly horizontal passage; an adit * Drift, linear term of a stochastic process * Drift (motorsport), the controlled sliding of a vehicle through a sharp turn, either via over-steering with sudden sharp braking, or counter-steering with a sudden "clutch kick" acceleration * Incremental changes: ** Drift (linguistics), a type of language ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pneumatic
Pneumatics (from Greek 'wind, breath') is the use of gas or pressurized air in mechanical systems. Pneumatic systems used in Industrial sector, industry are commonly powered by compressed air or compressed inert gases. A centrally located and electrically-powered Gas compressor, compressor powers Pneumatic cylinder, cylinders, air motors, pneumatic actuators, and other pneumatic devices. A pneumatic system controlled through manual or automatic solenoid valves is selected when it provides a lower cost, more flexible, or safer alternative to electric motors, and hydraulic actuators. Pneumatics also has applications in dentistry, construction, mining, and other areas. History Although the early history of pneumatics is somewhat unclear, blowguns are often considered the earliest pneumatic device, being created independently by various indigenous groups around the world. Bellows are an early form of air compressor used primarily for smelting and forging. Ctesibius of Alexand ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
