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Plymouth Breakwater
Plymouth Breakwater is a stone breakwater protecting Plymouth Sound and the anchorages near Plymouth, Devon, England. It is wide at the top and the base is . It lies in about of water. Around 4 million tons of rock were used in its construction in 1812 at the then-colossal cost of £1.5 million (equivalent to £ today). History In 1806, as the Napoleonic Wars impended, Lord St. Vincent commissioned John Rennie and Joseph Whidbey to plan a means of making Plymouth Bay a safe anchorage for the Channel Fleet. These plans may have been taken from ones made by George Matcham (1753 – 3 February 1833). In 1811 came the order to begin construction; Whidbey was appointed Acting Superintending Engineer. This task required great engineering, organizational and political skills, as the many strictly technical challenges were complicated by the significant resources devoted to the project, from which various parties evidenced a desire for advantage. Nearly 4,000,000 (four million) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Breakwater (structure)
A breakwater is a permanent structure constructed at a coastal area to protect against tides, currents, waves, and storm surges. Part of a coastal management system, breakwaters are installed to minimize erosion, and to protect anchorages, helping isolate vessels within them from marine hazards such as prop washes and wind-driven waves. A breakwater, also known in some contexts as a jetty, may be connected to land or freestanding, and may contain a walkway or road for vehicle access. On beaches where longshore drift threatens the erosion of beach material, smaller structures on the beach, usually perpendicular to the water's edge, may be installed. Their action on waves and current is intended to slow the longshore drift and discourage mobilisation of beach material. In this usage they are more usually referred to as groynes. Purposes Breakwaters reduce the intensity of wave action in inshore waters and thereby provide safe harbourage. Breakwaters may also be small structu ... [...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 lens redu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plymouth Breakwater Fort - Geograph
Plymouth () is a port city and unitary authority in South West England. It is located on the south coast of Devon, approximately south-west of Exeter and south-west of London. It is bordered by Cornwall to the west and south-west. Plymouth's early history extends to the Bronze Age when a first settlement emerged at Mount Batten. This settlement continued as a trading post for the Roman Empire, until it was surpassed by the more prosperous village of Sutton founded in the ninth century, now called Plymouth. In 1588, an English fleet based in Plymouth intercepted and defeated the Spanish Armada. In 1620, the Pilgrim Fathers departed Plymouth for the New World and established Plymouth Colony, the second English settlement in what is now the United States of America. During the English Civil War, the town was held by the Parliamentarians and was besieged between 1642 and 1646. Throughout the Industrial Revolution, Plymouth grew as a commercial shipping port, handling imports ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isophase Light
A light characteristic is all of the properties that make a particular navigational light identifiable. Graphical and textual descriptions of navigational light sequences and colours are displayed on nautical charts and in Light Lists with the chart symbol for a lighthouse, lightvessel, buoy or sea mark with a light on it. Different lights use different colours, frequencies and light patterns, so mariners can identify which light they are seeing. Abbreviations While light characteristics can be described in prose, e.g. "Flashing white every three seconds", lists of lights and navigation chart annotations use abbreviations. The abbreviation notation is slightly different from one light list to another, with dots added or removed, but it usually follows a pattern similar to the following (see the chart to the right for examples). * An abbreviation of the type of light, e.g. "Fl." for flashing, "F." for fixed. * The color of the light, e.g. "W" for white, "G" for green, "R" for red, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Penlee Point, Rame
Penlee Point ( kw, Penn Legh, meaning ‘stone-slab headland’) is a coastal headland to the southeast of the village of Rame in southeast Cornwall, UK. The point lies at the entrance to Plymouth Sound. Historical locations Above the point, a little below the Coastal Path, is Queen Adelaide's Grotto, built in 1827/1828 to commemorate the visit of King William IV and Queen Adelaide to Mount Edgcumbe. Penlee Battery is the former site of a fort, and is now a nature reserve A nature reserve (also known as a wildlife refuge, wildlife sanctuary, biosphere reserve or bioreserve, natural or nature preserve, or nature conservation area) is a protected area of importance for flora, fauna, or features of geological or .... See also * Penlee Point, Mousehole References Headlands of Cornwall {{Caradon-geo-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fog Signal Station
A fog signal station is a station at which a fog signal exists, but at which there is no lighthouse. A light tower might be appended to the station at a later date, as happened at The Cuckolds Light in Maine. A number of these stations were constructed along the California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ... coast, although few survive in their original form today. See also * Fiddler's Reach Fog Signal * Lime Point Light * Manana Island Sound Signal Station References * under "Manana Island Fog Signal Station" * Front matter, page 1. Navigation {{pharology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetylene
Acetylene ( systematic name: ethyne) is the chemical compound with the formula and structure . It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in its pure form and thus is usually handled as a solution. Pure acetylene is odorless, but commercial grades usually have a marked odor due to impurities such as divinyl sulfide and phosphine.Compressed Gas Association (1995Material Safety and Data Sheet – Acetylene As an alkyne, acetylene is unsaturated because its two carbon atoms are bonded together in a triple bond. The carbon–carbon triple bond places all four atoms in the same straight line, with CCH bond angles of 180°. Discovery Acetylene was discovered in 1836 by Edmund Davy, who identified it as a "new carburet of hydrogen". It was an accidental discovery while attempting to isolate potassium metal. By heating potassium carbonate with carbon at very high temperatures, he produce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Occulting Light
A light characteristic is all of the properties that make a particular navigational light identifiable. Graphical and textual descriptions of navigational light sequences and colours are displayed on nautical charts and in Light Lists with the chart symbol for a lighthouse, lightvessel, buoy or sea mark with a light on it. Different lights use different colours, frequencies and light patterns, so mariners can identify which light they are seeing. Abbreviations While light characteristics can be described in prose, e.g. "Flashing white every three seconds", lists of lights and navigation chart annotations use abbreviations. The abbreviation notation is slightly different from one light list to another, with dots added or removed, but it usually follows a pattern similar to the following (see the chart to the right for examples). * An abbreviation of the type of light, e.g. "Fl." for flashing, "F." for fixed. * The color of the light, e.g. "W" for white, "G" for green, "R" for red, " ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foghorn
A foghorn or fog signal is a device that uses sound to warn vehicles of navigational hazards such as rocky coastlines, or boats of the presence of other vessels, in foggy conditions. The term is most often used in relation to marine transport. When visual navigation aids such as lighthouses are obscured, foghorns provide an audible warning of rock outcrops, shoals, headlands, or other dangers to shipping. Description All foghorns use a vibrating column of air to create an audible tone, but the method of setting up this vibration differs. Some horns, such as the Daboll trumpet, used vibrating plates or metal reeds, a similar principle to a modern electric car horn. Others used air forced through holes in a rotating cylinder or disk, in the same manner as a siren. Semi-automatic operation of foghorns was achieved by using a clockwork mechanism (or "coder") to sequentially open the valves admitting air to the horns; each horn was given its own timing characteristics to help mari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Start Point Lighthouse
Start Point lighthouse was built in 1836 to protect shipping off Start Point, Devon, England. Open to the public in summer months, it is owned and operated by Trinity House. It has been designated by English Heritage as a grade II listed building. History Construction Start Point is one of twenty nine towers designed by James Walker. The lighthouse is in the gothic style, topped by a crenellated parapet. The main tower is built of tarred and white-painted granite ashlar with a cast-iron lantern roofed in copper. The tall circular tower is high with a moulded plinth and pedestal stage and two diminishing stages above that. There are two entrances porches, on the north and south sides. The porch on the south side is blocked and has a 4-centred arch hood mould, whilst the doorway to the north porch has a Tudor arch. Both have raised parapets with Trinity House arms. The inside of the tower includes a cantilevered granite staircase around the inside well of the tower with an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gunfleet Lighthouse
Gunfleet Lighthouse is a derelict screw-pile lighthouse lying in the North Sea, six miles off the coast at Frinton-on-Sea in Essex, constructed in 1850 by James Walker of Trinity House. George Henry Saunders was the contractor. Walker and Burges were the Engineers. It is in height and hexagonal in plan; mounted on seven piles forming a steel lattice and originally painted red. It was first lit on 1 May 1856, replacing a light vessel which had been on station there since 1850. When in use, the lighthouse was staffed by two keepers. They were accommodated in a single-storey dwelling, immediately below the lantern, which was divided into a living room (also used as a kitchen), a bed room and an oil room (in which the fuel for the lamps was stored). The walls and roof were of corrugated iron, with wrought iron angle plates. Additional storage space was provided in the 'inverted pyramid' beneath the dwelling, which was accessed by a ladder from the gallery. The light flashed red ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dioptric
Dioptrics is the branch of optics dealing with refraction, similarly the branch dealing with mirrors is known as catoptrics. Dioptrics is the study of the refraction of light, especially by lenses. Telescopes that create their image with an objective that is a convex lens ( refractors) are said to be "dioptric" telescopes. An early study of dioptrics was conducted by Ptolemy in relationship to the human eye as well as refraction in media such as water. The understanding of the principles of dioptrics was further expanded by Alhazen, considered the father of modern optics. See also * Diopter/ Dioptre (unit of measurement) * Dioptrice (work by Johannes Kepler) * Catoptrics (study of and optical systems utilizing reflection) * Catadioptrics (study of and optical systems utilizing reflection and refraction) * Optical telescope * List of telescope types * Image-forming optical system In optics, an image-forming optical system is a system capable of being used for imaging. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
