chimney |
bell |
top 10 words in brain distribution (in article): build wood structure wall design form city type floor construction |
top 10 words in brain distribution (in article): church time form century death world word iron life ancient |
top 10 words in brain distribution (not in article): material paint size surface cell window tree frame store plastic |
top 10 words in brain distribution (not in article): love sexual god woman people fuel bishop religion pyramid greek |
times more probable under chimney 30 20 10 6 4 2.5 1.25 1 1.25 2.5 4 6 10 20 30 times more probable under bell (words not in the model) | |
A chimney'" is a structure for venting hot flue gases or smoke from a boiler, stove, furnace or fireplace to the outside atmosphere. Chimneys are typically vertical, or as near as possible to vertical, to ensure that the gases flow smoothly, drawing air into the combustion in what is known as the stack, or chimney, effect. The space inside a chimney is called a "flue". Chimneys may be found in buildings, steam locomotives and ships. In the US, the term smokestack'" (colloquially, "'stack'") is also used when referring to locomotive chimneys. The term "'funnel'" is generally used for ships' chimneys and sometimes to refer to locomotive chimneys.. Chimneys are tall to increase their draw of air for combustion and to disperse pollutants in the flue gases over a greater area so as to reduce the pollutant concentrations in compliance with regulatory or other limits. History. Romans used tubes inside the walls to draw smoke out of bakeries but real chimneys appeared only in northern Europe in the 12th century. Industrial chimneys became common in the late 18th century. The earliest extant example of an English chimney is at Conisborough Keep in Yorkshire, which dates from 1185 AD. Chimneys have traditionally been built of brick, both in small and large buildings. Early chimneys were of a simple brick construction. Later chimneys were constructed by placing the bricks around tile liners. To control downdrafts venting caps (often called "chimney pots") with a variety of designs are sometimes placed on the top of chimneys. In the eighteenth and nineteenth centuries, the methods used to extract lead from its ore produced large amounts of toxic fumes. In the north of England, long near-horizontal chimneys were built, often more than 3 km (2 mi) long, which typically terminated in a short vertical chimney in a remote location where the fumes would cause less harm. Lead and silver deposits formed on the inside of these long chimneys, and periodically workers would be sent along the chimneys to scrape off these valuable deposits. Construction. Due to brick's limited ability to handle transverse loads, chimneys in houses were often built in a "stack", with a fireplace on each floor of the house sharing a single chimney, often with such a stack at the front and back of the house. Today's central heating systems have made chimney placement less critical, and the use of non-structural gas vent pipe allows a flue gas conduit to be installed around obstructions and through walls. In fact, many modern high-efficiency heating appliances do not require a chimney. Such appliances are typically installed near an outside wall, and a noncombustible wall thimble allows vent pipe to be run directly through the outside wall. Industrial chimneys are commonly referred to as flue gas stacks and are typically external structures, as opposed to being built into the wall of a building. They are generally located adjacent to a steam-generating boiler or industrial furnace and the gases are carried to it with ductwork. Today the use of reinforced concrete has almost entirely replaced brick as a structural component in the construction of industrial chimneys. Refractory bricks are often used as a lining, particularly if the type of fuel being burned generates flue gases containing acids. Modern industrial chimneys sometimes consist of a concrete windshield with a number of flues on the inside. The 300 metre chimney at Sasol Three consists of a 26 metre diameter windshield with four 4.6 metre diameter concrete flues which are lined with refractory bricks built on rings of corbels spaced at 10 metre intervals. The reinforced concrete can be cast by conventional formwork or sliding formwork. The height is to ensure the pollutants are dispersed over a wider area to meet legislative or safety requirements. Chimney tops. A chimney pot is placed on top of the chimney to inexpensively extend the length of the chimney, and to improve the chimney's draft. A chimney with more than one pot on it indicates that there is more than one fireplace on different floors sharing the chimney. A chimney cowl is placed on top of the chimney to prevent birds and squirrels from nesting in the chimney. They often feature a rain guard to keep rain from going down the chimney. A metal wire mesh is often used as a spark arrestor to minimize burning debris from rising out of the chimney and making it onto the roof. Although the masonry inside the chimney can absorb a large amount of moisture which later evaporates, rainwater can collect at the base of the chimney. Sometimes weep holes are placed at the bottom of the chimney to drain out collected water. A chimney cowl or wind directional cap is helmet shaped chimney cap that rotates to align with the wind and prevent a backdraft of smoke and wind back down the chimney. An H-style cap'" (cowl) is a chimney top constructed from chimney pipes shaped like the letter H. It is an age old method to regulate draft in situations where prevailing winds or turbulences cause down draft and backpuffing. Although the "'H cap'" has a distinctive advantage over most other downdraft caps, it fell out of favor because of it bulky looks. It is found mainly in marine use but has been gaining popularity again due to its energy saving functionality. The "'H-cap stabilizes the draft rather than increasing it. Other down draft caps are based on the Venturi effect, solving downdraft problems by increasing the up draft constantly resulting in much higher fuel consumption. A chimney damper is a metal spring door placed at the top of the chimney with a long metal chain that allows you to open and close the chimney from the fireplace. In the late Middle Ages in Western Europe the design of crow-stepped gables arose to allow maintenance access to the chimney top, especially for tall structures such as castles and great manor houses. Chimney draught or draft. When coal, oil, natural gas, wood or any other fuel is combusted in a stove, oven, fireplace, hot water boiler or industrial furnace, the hot combustion product gases that are formed are called flue gases. Those gases are generally exhausted to the ambient outside air through chimneys or industrial flue gas stacks (sometimes referred to as smokestacks). The combustion flue gases inside the chimneys or stacks are much hotter than the ambient outside air and therefore less dense than the ambient air. That causes the bottom of the vertical column of hot flue gas to have a lower pressure than the pressure at the bottom of a corresponding column of outside air. That higher pressure outside the chimney is the driving force that moves the required combustion air into the combustion zone and also moves the flue gas up and out of the chimney. That movement or flow of combustion air and flue gas is called "natural draught draft", "natural ventilation", "chimney effect", or "stack effect". The taller the stack, the more draught or draft is created. Designing chimneys and stacks to provide the correct amount of natural draught or draft involves a number design factors, many of which require trial-and-error reiterative methods. As a "first guess" approximation, the following equation can be used to estimate the natural draught draft flow rate by assuming that the molecular mass (i.e., molecular weight) of the flue gas and the external air are equal and that the frictional pressure and heat losses are negligible: Drawbacks. A characteristic problem of chimneys is they develop deposits of creosote on the walls of the structure when used with wood as a fuel. Some types of wood, such as pine, generate more creosote than others. Deposits of this substance can interfere with the airflow and more importantly, they are flammable and can cause dangerous chimney fires if the deposits ignite in the chimney. Thus, it is recommended — and in some countries even mandatory — that chimneys be inspected annually and cleaned on a regular basis to prevent these problems. The workers who perform this task professionally are called chimney sweeps. In the middle ages in some parts of Europe, a crow-stepped gable design was developed, partially to provide access to chimneys without use of ladders. Masonry (brick) chimneys have also proved particularly susceptible to crumbling during earthquakes. Government housing authorities in quake-prone cities like San Francisco and Los Angeles now recommend building new homes with stud-framed chimneys around a metal flue. Bracing or strapping old masonry chimneys has not proved to be very effective in preventing damage or injury from earthquakes. Perhaps predictably, a new industry provides "faux-brick" facades to cover these modern chimney structures. Other problems include "spalling" brick, in which moisture seeps into the brick and then freezes, cracking and flaking the brick and loosening mortar seals. Dual-use chimneys. Some very high chimneys are used for carrying antennas of mobile phone services and low power FM TV-transmitters. Special attention must be paid to possible corrosion problems if these antennas are near the exhaust of the chimney. In some cases the chimneys of power stations are used also as pylons. However this type of construction is not very common, because of corrosion problems of conductor cables. The Dům Dětí a Mládeže | A bell'" is a simple sound-making device. The bell is a percussion instrument and an idiophone. Its form is usually an open-ended hollow drum which resonates upon being struck. The striking implement can be a tongue suspended within the bell, known as a "clapper", a small, free sphere enclosed within the body of the bell, or a separate mallet. Bells are usually made of cast metal, but small bells can also be made from ceramic or glass. Bells can be of all sizes: from tiny dress accessories to church bells weighing many tons. Church and temple bells. In the Western world, its most classical form is a church bell or town bell, which is hung within a tower and sounded by having the entire bell swung by ropes, whereupon an internal hinged clapper strikes the body of the bell (called a free-swinging bell). A set of bells, hung in a circle for change ringing, is known as a ring of bells. In the Eastern world, the traditional forms of bells are temple and palace bells, small ones being rung by a sharp rap with a stick, and very large ones rung by a blow from the outside by a large swinging beam. The striking technique is employed worldwide for some of the largest tower-borne bells, because swinging the bells themselves could damage their towers. In the Roman Catholic Church and among some High Lutherans and Anglicans, small hand-held bells, called Sanctus or sacring bells, are often rung by a server at Mass when the priest holds high up first the host, and then the chalice immediately after he has said the words of consecration over them (the moment known as the Elevation). This serves to indicate to the congregation that the bread and wine have just been transformed into the body and blood of Christ (see transubstantiation), or, in the alternative Reformation teaching, that Christ is now bodily present in the elements, and that what the priest is holding up for them to look at is Christ himself (see consubstantiation). Japanese religious bells. Japanese Shintoist and Buddhist bells are used in religious ceremonies. "Suzu", a homophone meaning both "cool and refreshing," are spherical bells which contain metal pellets that produce sound from the inside. The hemispherical bell is the "Kane" bell, which is struck on the outside. See also Kane (musical instrument). Buddhist bells. Buddhist bells are used in religious ceremonies. Bell construed as a cause for war. On January 15, 1602 ("Keichō 7"), a fire broke out at Hōkō-ji, Buddhist temple complex in Kyoto. The great image of the Buddha and the structure housing the statue, the "Daibutsu-den", were both consumed by the flames. In 1610, Toyotomi Hideyori decided to sponsor rebuilding the Hōkō-ji and he also decided to order a great bell cast in bronze. On August 24, 1614 ("Keichō 19"), the huge new bronze bell was cast successfully. Dedication ceremonies were scheduled, but at the last minute, Tokugawa Ieyasu forbade the ceremonies to take place because he construed inscriptions on the bell to have been a personal affront: This contrived dispute led to the, which was a series of battles between armies of the Tokugawa shogunate and the samurai of the Toyotomi clan. The siege lasted through 1615. It is conventionally divided into two stages: the Winter Campaign and the Summer Campaign. In the end, the total destruction of the Toyotomi eliminated the last major opposition to the shogunate which would come to dominate Japan for the next 250 years. Bellmaking. The process of casting bells is called bellmaking or bellfounding, and in Europe dates to the 4th or 5th century. The traditional metal for these bells is a bronze of about 23% tin. Known as "bell metal", this alloy is also the traditional alloy for the finest Turkish and Chinese cymbals. Other materials sometimes used for large bells include brass and iron. Bells are always cast mouth down. Bells are made to exact formulas, so that given the diameter it is possible to calculate every dimension, and its musical note, or tone. The frequency of a bell's note in Hz varies with the square of its thickness, and inversely with its diameter. Much experimentation has been devoted to determining the exact shape that will give the best tone. The thickness of a church bell at its thickest part, called the 'sound bow' is usually one thirteenth its diameter. If the bell is mounted as cast, it is called a "maiden bell" while "tuned bells" are worked after casting to produce a precise note. Bell towers. Bells are also associated with clocks, indicating the hour by ringing. Indeed, the word "clock" comes from the Latin word "cloca", meaning bell. Clock towers or bell towers can be heard over long distances which was especially important in the time when clocks were too expensive for widespread use. In the case of clock towers and grandfather clocks, a particular sequence of tones may be played to represent the hour. One common pattern is called the "Westminster Quarters," a sixteen-note pattern named after the Palace of Westminster which popularized it as the measure used by "Big Ben". Bells as musical instruments. Some bells are used as musical instruments, such as carillons, (clock) chimes, or ensembles of bell-players, called bell choirs, using hand-held bells of varying tones. A "ring of bells" is a set of 4 to twelve bells or more used in change ringing, a particular method of ringing bells in patterns. A peal in changing ringing may have bells playing for several hours, playing 5,000 or more patterns without a break or repetition.. Ancient Chinese bells. The ancient Chinese bronze chime bells called bianzhong or (鐘) are among the highest achievements of Chinese bronze casting technology. These chime bells were used as polyphonic musical instruments and some of these bells have been dated at between 2000 to 3600 years old. The secret of the design and the method of casting zhong bells, which was known only to the Chinese in antiquity, was lost in later generations. It was not fully rediscovered and understood until 1978, when a complete ceremonial set of 65 "zhong" bells was found in a near-perfect state of preservation during the excavation of the of Marquis Yi, who died ca. 430BCE. Yi was ruler of Zeng, one of the Warring States which at the time of his death was under control of the Chǔ state. This region is now part of the present-day Hubei province. Although tuned bells have been created and used for musical performance in many cultures, zhong are unique among all other types of cast bells in several respects. They have a lens-shaped (rather than circular) section and the bell mouth has a distinctive "cutaway" profile, and this special shape gives zhong bells the remarkable ability to produce, depending on where they are struck. The interval between these notes on each bell is either a major or minor third, equivalent to a distance of four or five notes on a piano.. The bells of Marquis Yi, which are still fully playable after almost 2500 years, cover a range of slightly less than five octaves but thanks to their twin-tone capability, the set can sound a complete 12-tone scale, predating the development of the European 12-tone system by some 2000 years, and can play melodies in diatonic and pentatonic scales These bells usually have inscriptions on them from which scholars used as references for studying ancient Chinese writings (also known as Bronzeware script). Another related ancient Chinese musical instrument is called qing (pinyin qing4) but it was made of stone instead of metal. Konguro'o. Konguro'o is a small bell, which as well as Djalaajyn firstly had the utilitarian purposes and only after artistic ones. Konguro'o sounded by the time of moving to the new places, being fastened to the horse harness it created very specific "smart" sound background. Konguro'o also hanged on the neck of leader goat, which leads the flock of sheep in some definite direction. That is why in folk memory almost magic sound of konguro'o was associated with nomadic mode of life. To make this instrument Kyrgyz foremen used cooper, bronze, iron and brass. They also decorated it with artistic carving and covered with silver. Sizes of the instruments might vary in considerable limits, what depended on its function. Every bell had its own timbre. Chimes. A variant on the bell is the tubular bell. Several of these metal tubes which are struck manually with hammers, form an instrument named "tubular bells" or "chimes". In the case of wind or aeolian chimes, the tubes are blown against one another by the wind. Farm bells. Whereas the church and temple bells called to mass or religious service, bells were used on farms for more secular signaling. The greater farms in Scandinavia usually had a small bell-tower resting on the top of the barn. The bell was used to call the workers from the field at the end of the day's work. In folk tradition, it is recorded that each church and possibly several farms had their specific rhymes connected to the sound of the specific bells. An example is the Pete Seeger song "The Bells of Rhymney". |