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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 reed (music), reeds, a similar principle to a modern electric Vehicle horn, car horn. Others used air forced through holes in a rotating cylinder or disk, in the same manner as a siren (alarm), 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 ... [...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 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 promontory, prom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siren (alarm)
A siren is a noise-making warning device. There are two general types: mechanical sirens and electronic sirens. Civil defense sirens are mounted in fixed locations and used to warn of natural disasters or attacks. Sirens are used on emergency service vehicles such as ambulances, police cars, and fire engines. Many fire sirens (used for summoning volunteer firefighters) serve double duty as tornado or civil defense sirens, alerting an entire community of impending danger. Most fire sirens are either mounted on the roof of a fire station or on a pole next to the fire station. Fire sirens can also be mounted on or near government buildings, on tall structures such as water towers, as well as in systems where several sirens are distributed around a town for better sound coverage. Most fire sirens are single tone and mechanically driven by electric motors with a rotor attached to the shaft. Some newer sirens are Electronics, electronically driven speakers. Fire sirens are often cal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Whistle
A whistle is a musical instrument which produces sound from a stream of gas, most commonly air. It is a type of Fipple, fipple flute, and may be mouth-operated, or powered by air pressure, steam, or other means. Whistles vary in size from a small slide whistle or nose flute type to a large multi-piped Organ (music), church organ. Whistles have been around since early humans first carved out a gourd or branch and found they could make sound with it. In prehistoric Egypt, small shells were used as whistles. Many present day Wind instrument, wind instruments are inheritors of these early whistles. With the rise of more mechanical power, other forms of whistles have been developed. One characteristic of a whistle is that it creates a pure, or nearly pure, Musical tone, tone. The conversion of flow energy to sound comes from an interaction between a solid material and a fluid stream. The forces in some whistles are sufficient to set the solid material in motion. Classic examples a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steam
Steam is water vapor, often mixed with air or an aerosol of liquid water droplets. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporization. Saturated or superheated steam is invisible; however, wet steam, a visible mist or aerosol of water droplets, is often referred to as "steam". When liquid water becomes steam, it increases in volume by 1,700 times at standard temperature and pressure; this change in volume can be converted into work (physics), mechanical work by steam engines such as reciprocating engine, reciprocating piston type engines and steam turbines, which are a sub-group of steam engines. Piston type steam engines played a central role in the Industrial Revolution and modern steam turbines are used to generate more than 80% of the world's electricity. If liquid water comes in contact with a very hot surface or depressurizes quickly below its vapor pressure, vapour pressure, it can create a steam exp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Automation
Automation describes a wide range of technologies that reduce human intervention in processes, mainly by predetermining decision criteria, subprocess relationships, and related actions, as well as embodying those predeterminations in machines. Automation has been achieved by various means including Mechanical system, mechanical, hydraulic, pneumatic, electrical, electronic devices, and computers, usually in combination. Complicated systems, such as modern Factory, factories, airplanes, and ships typically use combinations of all of these techniques. The benefit of automation includes labor savings, reducing waste, savings in electricity costs, savings in material costs, and improvements to quality, accuracy, and precision. Automation includes the use of various equipment and control systems such as machinery, processes in factories, boilers, and heat-treating ovens, switching on telephone networks, steering, Stabilizer (ship), stabilization of ships, aircraft and other applic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trinity House Warning Notice
The Trinity (, from 'threefold') is the Christian doctrine concerning the nature of God, which defines one God existing in three, , consubstantial divine persons: God the Father, God the Son (Jesus Christ) and God the Holy Spirit, three distinct persons ('' hypostases'') sharing one essence/substance/nature (''homoousion''). As the Fourth Lateran Council declared, it is the Father who s, the Son who is , and the Holy Spirit who proceeds. In this context, one essence/nature defines God is, while the three persons define God is. This expresses at once their distinction and their indissoluble unity. Thus, the entire process of creation and grace is viewed as a single shared action of the three divine persons, in which each person manifests the attributes unique to them in the Trinity, thereby proving that everything comes "from the Father", "through the Son", and "in the Holy Spirit". This doctrine is called Trinitarianism, and its adherents are called Trinitarians, while i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triangle (musical Instrument)
The triangle, or musical triangle, is a musical instrument in the percussion family, classified as an idiophone in the Hornbostel-Sachs classification system. Triangles are made from a variety of metals including aluminum, beryllium copper, brass, bronze, iron, and steel. The metal is bent into a triangular shape with one open end. The instrument is usually held by a loop of some form of thread or wire at the top curve to enable the triangle to vibrate, and it is struck with a metal rod called a "beater". The triangle theoretically has indefinite pitch, and produces a plurality of overtones when struck with an appropriate beater. History Iconography is the primary source for knowledge of the history of the triangle, and provides insight into the musical and social context in which the instrument developed. Some scholars believe the triangle to be a direct descendant of the ancient Egyptian sistrum. Others do not go quite so far, referring to the triangle as being " ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Portland Bill
Portland Bill is a narrow promontory (or bill) at the southern end of the Isle of Portland, and the southernmost point of Dorset, England. One of Portland's most popular destinations is Portland Bill Lighthouse. Portland's coast has been notorious for the number of shipwrecked vessels over the centuries. The dangerous coastline features shallow reefs and the Shambles sandbank, made more hazardous due to the strong Portland tidal race. The Bill is an important way-point for coastal traffic, and three lighthouses have been built to protect shipping. The original two worked as a pair from 1716, and they were replaced in 1906 by the current one. History From Roman times, beacon fires were lit to warn ships of the danger of the Bill. A petition to Trinity House was put forward for a lighthouse in the early 18th century, but Trinity House opposed it. They later conceded that a lighthouse was needed and George I granted the patent on 26 May 1716. Trinity House issued a lease to W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
