Panther Books Ltd was a British publishing house active in the 1950s and 1960s, specialising in paperback fiction. It was established in May 1952 by Hamilton's Ltd and titles carried the line "A Panther Book" or "Panther Science Fiction" on the cover. Science fiction was one of the major genres published by Panther Books and titles included Ray Bradbury's The Golden Apples of the Sun and Asimov's Foundation Trilogy. In 1954 Gordon Landsborough was started improving the quality of the imprint. Instead of publishing original genre novels in paperback and hardback, Panther Books became a reprint publisher, doing paperback reprints of best-selling hardcover novels from other publishers; the quality of the cover art was improved and the list expanded to include non-fiction titles and fiction titles by internationally known, best-selling writers. By at least April 1966, books published under the Panther name indicate that the business was based at 108 Brompton Road, London, S. W.5. However, records of the tumultuous process of mergers and acquisitions in the publishing industry show that by 1968, Granada Group Ltd had acquired a number of publishers who became subsidiary companies of Granada Publishing Ltd.
These included, amongst others, Panther Books Ltd, thus Panther Science Fiction became a Granada imprint. In 1983, Granada sold the publishing side of its business to the Scottish publishers William Collins, Sons & Co, based in Glasgow. In 1989, William Collins Sons & Co merged with the American Harper & Row publishers, located in New York, to form HarperCollins, the British side of the company being managed through Harper Collins Publishers Ltd. Harper Collins Publishers continued to trade in 2003 with head offices at Bishopbriggs, employing about 500 people. Records of Granada Publishing Ltd, Glasgow University Archives Service Records of William Collins, Sons and Co Ltd, Glasgow University Archives Service
The Mothman Prophecies (film)
The Mothman Prophecies is a 2002 U. S. supernatural horror-mystery film directed by Mark Pellington, starring Richard Gere and Laura Linney. Based on the 1975 book of the same name by parapsychologist and Fortean author John Keel, the screenplay was written by Richard Hatem; the story follows a reporter who researches the legend of the Mothman. After a lengthy detour he has no memory of, he finds himself in Point Pleasant, West Virginia, where there have been sightings of an unusual creature and other unexplained phenomena. Many of the sightings remind him of his dead wife; as he becomes drawn into mysterious forces at work, he hopes they can reconnect him to his wife, while the local sheriff becomes concerned about his obsessions. The film claims to be based on actual events that occurred between November 1966 and December 1967 in Point Pleasant, as described by Keel, it was shot in Pittsburgh and Kittanning and was released to mixed reviews. Washington Post columnist John Klein and his wife Mary are involved in an accident when Mary swerves to avoid a black, flying figure.
John survives the crash unscathed. After Mary dies of an unrelated brain tumor, John discovers mysterious drawings of the creature that she had created whilst in hospital. Two years John becomes lost in West Virginia and inexplicably finds himself in Point Pleasant, hundreds of miles off his route. Driving in the middle of the night, his car breaks down; the owner, Gordon Smallwood, holds him at gunpoint. Local police officer Connie Mills defuses the situation while Gordon explains that this is the third consecutive night John has knocked on his door asking to use a phone, much to John's confusion. John considers how he ended up so far from his original destination. Officer Mills mentions to John that many strange things have been occurring in the past few weeks and that people report seeing a large winged creature like a giant moth with red eyes, she tells John about a strange dream she had, in which the words "Wake up, Number 37" were spoken to her. During a conversation one day, Gordon reveals to John that he has heard voices coming from his sink telling him that, in Denver, "99 will die".
While discussing the day's events at a local diner, John notices that the news is showing the story of an airplane crash in Denver that killed all 99 passengers aboard. The next night Gordon frantically explains that the voices in his head emanate from a being named Indrid Cold; that night Gordon calls John and says that he is standing next to someone named Indrid Cold. While John keeps Cold on the line, Officer Mills checks on Gordon. Cold answers John's questions, including ones he could not know the answers to, convincing John that Cold is a supernatural being; this episode starts a string of supernatural calls to John's motel room. One tells him. John receives a call from Gordon and rushes to his home to check on him, he finds Gordon outside, dead from exposure. John becomes obsessed with the being, dubbed the Mothman, he meets an expert on the subject, Alexander Leek, who explains its nature and discourages John from becoming further involved. However, when John learns the Governor plans to tour a chemical plant located on the Ohio River the following day, he becomes convinced the tragedy will occur there.
Officer Mills and the governor ignore his warnings, nothing happens during the tour. Soon afterwards, John receives a mysterious message that instructs him to await a call from his deceased wife Mary back in Georgetown, he returns home. On Christmas Eve, Officer Mills calls and convinces him to ignore the phone call from "Mary", return to Point Pleasant, join her. Though anguished, John agrees; as John reaches the Silver Bridge, a malfunctioning traffic light causes traffic congestion. As John walks onto the bridge to investigate, the bolts and supports of the bridge strain; the bridge comes apart, John realizes that the prophesied tragedy on the Ohio River was about the bridge. As the bridge collapses, Officer Mills' car falls into the water. John pulls her from the river and up to safety; as the two sit on the back of an ambulance, they see that 36 people have been killed, making Connie the "number 37" from her dream. The cause of the bridge collapse was never determined. Although the Mothman has been sighted in other parts of the world, it was never seen again in Point Pleasant.
Richard Gere as John Klein Laura Linney as Connie Mills Will Patton as Gordon Smallwood Debra Messing as Mary Klein Lucinda Jenney as Denise Smallwood Alan Bates as Alexander Leek David Eigenberg as Ed Fleischman Bob Tracey as Cyrus Bills Mark Pellington as Indrid Cold "The Mothman" Writer Paul Meehan judged the film's explanation of the Mothman to be a "confused mish-mosh of science fiction and demonology" and likened it to the television series The X-Files, though preserving Keel's "breathless hysteria". Meehan remarked that "Aliens spouting prophetic utterances are rare in UFO literature". In contrast to Meehan, author Jason Horsley declared The Mothman Prophecies "probably the most effective depiction of demonic forces at work" in U. S. cinema. Horsley assessed its approach to the Mothman legend as depicting a "schizophrenic nature of reality", fulfilling a "revelation" purpose in horror film, as it "strips away the comfortable veneer of consensus reality to reveal the seething abyss of irrationality".
Horsley argued the film's Mothman arrives from a foreign dimension, but being without "physical existence", it is a product of the minds of Point Pleasant's citizens, based on "formless and impersonal energy
Point Pleasant, West Virginia
Point Pleasant is a city in and the county seat of Mason County, West Virginia, USA, at the confluence of the Ohio and Kanawha Rivers. The population was 4,350 at the 2010 census, it is the principal city of WV-OH Micropolitan Statistical Area. According to the United States Census Bureau, the city has a total area of 3.10 square miles, of which, 2.40 square miles is land and 0.70 square miles is water. Point Pleasant is located at 38°51′27″N 82°7′43″W. Point Pleasant is home to Tu-Endie-Wei State Krodel Park; as of the census of 2010, there were 4,350 people, 2,014 households, 1,162 families residing in the city. The population density was 1,812.5 inhabitants per square mile. There were 2,244 housing units at an average density of 935.0 per square mile. The racial makeup of the city was 95.9% White, 1.3% African American, 0.3% Native American, 0.6% Asian, 0.3% Pacific Islander, 1.7% from two or more races. Hispanic or Latino of any race were 0.6% of the population. There were 2,014 households of which 25.7% had children under the age of 18 living with them, 37.9% were married couples living together, 16.0% had a female householder with no husband present, 3.8% had a male householder with no wife present, 42.3% were non-families.
38.5% of all households were made up of individuals and 18.7% had someone living alone, 65 years of age or older. The average household size was 2.15 and the average family size was 2.82. The median age in the city was 44 years. 21.5% of residents were under the age of 18. The gender makeup of the city was 44.9% male and 55.1% female. As of the census of 2000, there were 4,637 people, 2,107 households, 1,310 families residing in the city; the population density was 1,945.6 people per square mile. There were 2,313 housing units at an average density of 970.5 per square mile. The racial makeup of the city was 96.57% White, 1.90% African American, 0.15% Native American, 0.60% Asian, 0.09% from other races, 0.69% from two or more races. Hispanic or Latino of any race were 0.54% of the population. There were 2,107 households out of which 26.3% had children under the age of 18 living with them, 44.7% were married couples living together, 14.4% had a female householder with no husband present, 37.8% were non-families.
34.8% of all households were made up of individuals and 17.8% had someone living alone, 65 years of age or older. The average household size was 2.18 and the average family size was 2.80. In the city, the population was spread out with 21.3% under the age of 18, 8.4% from 18 to 24, 23.7% from 25 to 44, 26.2% from 45 to 64, 20.4% who were 65 years of age or older. The median age was 43 years. For every 100 females, there were 83.6 males. For every 100 females age 18 and over, there were 75.3 males. The median income for a household in the city was $27,022, the median income for a family was $33,527. Males had a median income of $31,657 versus $16,607 for females; the per capita income for the city was $16,692. About 22.2% of families and 24.2% of the population were below the poverty line, including 37.9% of those under age 18 and 13.3% of those age 65 or over. In the second half of 1749, the French explorer Pierre Joseph Céloron de Blainville claimed French sovereignty over the Ohio Valley, burying a lead plaque at the meeting point of the Ohio and Kanawha Rivers.
The text on the plaque is as follows: L'AN 1749 DV REGNE DE LOVIS XV ROY DE FRANCE, NOVS CELORON, COMMANDANT D'VN DETACHEMENT ENVOIE PAR MONSIEVR LE MIS. DE LA GALISSONIERE, COMMANDANT GENERAL DE LA NOUVELLE FRANCE POVR RETABLIR LA TRAN QUILLITE DANS QUELQUES VILLAGES SAUVAGES DE CES CANTONS, AVONS ENTERRE CETTE PLAQUE AU CONFLUENT DE L'OHIO ET DE TCHADAKOIN CE 29 JVILLET, PRES DE LA RIVIERE OYO AUTREMENT BELLE RIVIERE, POUR MONUMENT DU RENOUVELLEMENT DE POSSESSION QUE NOUS AVONS PRIS DE LA DITTE RIVIERE OYO, ET DE TOUTES CELLE~ QUI Y TOMBENT, ET DE TOUTES LES TERRES DES DEUX COTES JVSQVE AVX SOURCES DES DITTES RIVIERES AINSI QV'EN ONT JOVY OU DV JOVIR LES PRECEDENTS ROIS DE FRANCE, ET QU'ILS S'Y SONT MAINTENVS PAR LES ARMES ET PAR LES TRAIT TES, SPECIALEMENT PAR CEVX DE RISWICK D'VTRECHT ET D'AIX LA CHAPELLE. Céloron's expedition was a diplomatic failure since the local tribes remained pro-English, English representatives in the region refused to go away; this was, therefore, a prelude to a series of incidents that would lead to the loss of New France and the domination of eastern North America by the British Empire following the defeat of France in the French and Indian War.
The expedition can be seen in more positive terms as a geographical project, since the Céloron expedition was the starting point for the first map of the Ohio Valley. The map was the work of the Jesuit Joseph Pierre de Bonnecamps. In 1770, Colonel George Washington visited the confluence that would become Point Pleasant proceeded 14 miles up the "Great Kanawha" and reported that "This Country abounds
The Silver Bridge was an eyebar-chain suspension bridge built in 1928 and named for the color of its aluminum paint. The bridge carried U. S. Route 35 over the Ohio River, connecting Point Pleasant, West Virginia, Gallipolis, Ohio. On December 15, 1967, the Silver Bridge collapsed while it was full of rush-hour traffic, resulting in the deaths of 46 people. Two of the victims were never found. Investigation of the wreckage pointed to the cause of the collapse being the failure of a single eyebar in a suspension chain, due to a small defect 0.1 inches deep. Analysis showed that the bridge was carrying much heavier loads than it had been designed for and had been poorly maintained; the collapsed bridge was replaced by the Silver Memorial Bridge, completed in 1969. At the time of the Silver Bridge construction, eyebar bridges had been built for about 100 years; such bridges had been constructed from redundant bar links, using rows of four to six bars, sometimes using several such chains in parallel.
An example can be seen in the Clifton Suspension Bridge, designed by Isambard Kingdom Brunel. The chain eyebars are redundant in two dimensions; this is an early suspension bridge still in service. Other bridges of similar design include the earlier road bridge over the Menai Strait built by Thomas Telford in 1826; the eyebars in the Silver Bridge were not redundant, as links were composed of only two bars each, of high-strength steel, rather than a thick stack of thinner bars of modest material strength "combed" together, as is usual for redundancy. With only two bars, the failure of one could impose excessive loading on the second, causing total failure — which would be unlikely if more bars were used. While a low-redundancy chain can be engineered to the design requirements, the safety is dependent upon correct, high-quality manufacturing and maintenance. In comparison, the Brooklyn Bridge, with wire-cable suspension, was designed with an excess strength factor of six. Wire cables have high levels of redundancy, with the failure of a single wire strand unnoticeable.
During its construction it was discovered. To compensate for the rejected steel wire in the cables, 150 more good steel wires per cable were added to bring the total up to 5,434 redundant strands; the designer's son decided the safety factor may have been reduced, but was far more than sufficient. The towers were "rocker" towers, which allowed the bridge to respond to various live loads by a slight tipping of the supporting towers, which were parted at the deck level, rather than passing the suspension chain over a lubricated or tipping saddle, or by stressing the towers in bending; the towers required the chain on both sides for their support. At the time of the bridge construction, a typical family automobile was the Ford Model T, with a weight of about 1,500 pounds; the maximum permitted. By contrast, at the time of the collapse, a typical family automobile weighed about 4,000 pounds and the large truck limit was 60,000 pounds or more. Bumper-to-bumper traffic jams on the bridge were much more common, occurring several times a day, five days each week, thus causing more stress to the bridge elements.
The bridge failure was due to a defect in a single link, eye-bar 330, on the north of the Ohio subsidiary chain, the first link below the top of the Ohio tower. A small crack was formed through fretting wear at the bearing, grew through internal corrosion, a problem known as stress corrosion cracking; the crack was only about 0.1 inches deep when it went critical, it broke in a brittle fashion. Growth of the crack was exacerbated by residual stress in the eyebar created during manufacture; when the lower side of the eyebar failed, all the load was transferred to the other side of the eyebar, which failed by ductile overload. The joint was held together only by three eyebars, another slipped off the pin at the center of the bearing, so the chain was severed. Collapse of the entire structure was inevitable since all parts of a suspension bridge are in equilibrium with one another. Witnesses afterward estimated; the damage to the link would have been difficult to see during inspection of the bridge: Inspection prior to construction would not have been able to notice the tiny crack... the only way to detect the fracture would have been to disassemble the eye-bar.
The technology used for inspection at the time was not capable of detecting such cracks. The collapse focused much needed attention on the condition of older bridges, leading to intensified inspection protocols and numerous eventual replacements. There were only two bridges built to a similar design, one upstream at St. Marys, West Virginia, the notably longer Hercilio Luz Bridge at Florianópolis, Brazil; the St. Marys bridge was closed to traffic and the bridge was demolished by the state in 1971. A small truss bridge was kept to allow access to an island in the river; the Hi Carpenter Memorial Bridge was built to replace the demolished bridge. The Hercilio Luz Bridge remained in active service until 1991 and still stands
Stress corrosion cracking
Stress corrosion cracking is the growth of crack formation in a corrosive environment. It can lead to unexpected sudden failure of ductile metals subjected to a tensile stress at elevated temperature. SCC is chemically specific in that certain alloys are to undergo SCC only when exposed to a small number of chemical environments; the chemical environment that causes SCC for a given alloy is one, only mildly corrosive to the metal. Hence, metal parts with severe SCC can appear bright and shiny, while being filled with microscopic cracks; this factor makes it common for SCC to go undetected prior to failure. SCC progresses and is more common among alloys than pure metals; the specific environment is of crucial importance, only small concentrations of certain active chemicals are needed to produce catastrophic cracking leading to devastating and unexpected failure. The stresses can be the result of the crevice loads due to stress concentration, or can be caused by the type of assembly or residual stresses from fabrication.
Certain austenitic stainless steels and aluminium alloys crack in the presence of chlorides, mild steel cracks in the presence of alkali and nitrates, copper alloys crack in ammoniacal solutions. This limits the usefulness of austenitic stainless steel for containing water with higher than few ppm content of chlorides at temperatures above 50 °C. Of concern is the fact that high-tensile structural steels have been known to crack in an unexpectedly brittle manner in a whole variety of aqueous environments when chlorides are present. With the possible exception of the latter, a special example of hydrogen cracking, all the others display the phenomenon of subcritical crack growth, i.e. small surface flaws propagate under conditions where fracture mechanics predicts that failure should not occur. That is, in the presence of a corrodent, cracks develop and propagate well below KIc. In fact, the subcritical value of the stress intensity, designated as KIscc, may be less than 1% of KIc, as the following table shows: A similar process occurs in polymers, when products are exposed to specific solvents or aggressive chemicals such as acids and alkalis.
As with metals, attack is confined to particular chemicals. Thus polycarbonate is sensitive to attack by alkalis, but not by acids. On the other hand, polyesters are degraded by acids, SCC is a failure mechanism. Polymers are susceptible to environmental stress cracking where attacking agents do not degrade the materials chemically. Nylon is sensitive to degradation by acids, a process known as hydrolysis, nylon mouldings will crack when attacked by strong acids. For example, the fracture surface of a fuel connector showed the progressive growth of the crack from acid attack to the final cusp of polymer. In this case the failure was caused by hydrolysis of the polymer by contact with sulfuric acid leaking from a car battery; the degradation reaction is the reverse of the synthesis reaction of the polymer: Cracks can be formed in many different elastomers by ozone attack, another form of SCC in polymers. Tiny traces of the gas in the air will attack double bonds in rubber chains, with natural rubber, styrene-butadiene rubber, nitrile butadiene rubber being most sensitive to degradation.
Ozone cracks form in products under tension, but the critical strain is small. The cracks are always oriented at right angles to the strain axis, so will form around the circumference in a rubber tube bent over; such cracks are dangerous when they occur in fuel pipes because the cracks will grow from the outside exposed surfaces into the bore of the pipe, so fuel leakage and fire may follow. The problem of ozone cracking can be prevented by adding anti-ozonants to the rubber before vulcanization. Ozone cracks were seen in automobile tire sidewalls, but are now seen thanks to the use of these additives. On the other hand, the problem seals; this effect is less common in ceramics which are more resilient to chemical attack. Although phase changes are common in ceramics under stress these result in toughening rather than failure. Recent studies have shown that the same driving force for this toughening mechanism can enhance oxidation of reduced cerium oxide, resulting in slow crack growth and spontaneous failure of dense ceramic bodies.
Given that most glasses contain a substantial silica phase, the introduction of water can chemically weaken the bonds preventing subcritical crack propagation. Indeed, the silicon oxygen bonds present at the tip of a crack are strained, thus more susceptible to chemical attack. In the instance of chemical attack by water, silicon-oxygen bonds bridging the crack are separated into non-connected silicon hydroxide groups; the addition of external stress will serve to further weaken these bonds. Subcritical crack propagation in glasses falls into three regions. In region I, the velocity of crack propagation increases with ambient humidity due to stress-enhanced chemical reaction between the glass and water. In region II, crack propagation velocity is diffusion controlled and dependent on the rate at which chemical reactants can be transported to the tip of the crack. In region III, crack propagation is independent of its environment, having reached a critical stress intensity. Chemicals other than water, like ammonia, can induce subcritical crack propagation in silica glass, but they must have an electron do
The Ohio River is a 981-mile long river in the midwestern United States that flows southwesterly from western Pennsylvania south of Lake Erie to its mouth on the Mississippi River at the southern tip of Illinois. It is the second largest river by discharge volume in the United States and the largest tributary by volume of the north-south flowing Mississippi River that divides the eastern from western United States; the river flows through or along the border of six states, its drainage basin includes parts of 15 states. Through its largest tributary, the Tennessee River, the basin includes several states of the southeastern U. S, it is the source of drinking water for three million people. The lower Ohio River just below Louisville is obstructed by rapids known as the Falls of the Ohio where the water level falls 26ft. in 2 miles and is impassible for navigation. The McAlpine Locks and Dam, a shipping canal bypassing the rapids, now allows commercial navigation from the Forks of the Ohio at Pittsburgh to the Port of New Orleans at the mouth of the Mississippi on the Gulf of Mexico.
The name "Ohio" comes from the Ohi: yo', lit. "Good River". Discovery of the Ohio River may be attributed to English explorers from Virginia in the latter half of the 17th century. In his Notes on the State of Virginia published in 1781–82, Thomas Jefferson stated: "The Ohio is the most beautiful river on earth, its current gentle, waters clear, bosom smooth and unbroken by rocks and rapids, a single instance only excepted." In the late 18th century, the river was the southern boundary of the Northwest Territory. It became a primary transportation route for pioneers during the westward expansion of the early U. S; the river is sometimes considered as the western extension of the Mason–Dixon Line that divided Pennsylvania from Maryland, thus part of the border between free and slave territory, between the Northern and Southern United States or Upper South. Where the river was narrow, it was the way to freedom for thousands of slaves escaping to the North, many helped by free blacks and whites of the Underground Railroad resistance movement.
The Ohio River is a climatic transition area, as its water runs along the periphery of the humid subtropical and humid continental climate areas. It is inhabited by flora of both climates. In winter, it freezes over at Pittsburgh but farther south toward Cincinnati and Louisville. At Paducah, Kentucky, in the south, near the Ohio's confluence with the Mississippi, it is ice-free year-round; the name "Ohio" comes from the Seneca language, Ohi:yo', a proper name derived from ohiːyoːh, therefore translating to "Good River". "Great river" and "large creek" have been given as translations. Native Americans, including the Lenni Lenape and Iroquois, considered the Ohio and Allegheny rivers as the same, as is suggested by a New York State road sign on Interstate 86 that refers to the Allegheny River as Ohi:yo'. An earlier Miami-Illinois language name was applied to the Ohio River, Mosopeleacipi. Shortened in the Shawnee language to pelewa thiipi, spelewathiipi or peleewa thiipiiki, the name evolved through variant forms such as "Polesipi", "Peleson", "Pele Sipi" and "Pere Sipi", stabilized to the variant spellings "Pelisipi", "Pelisippi" and "Pellissippi".
Applied just to the Ohio River, the "Pelisipi" name was variously applied back and forth between the Ohio River and the Clinch River in Virginia and Tennessee. In his original draft of the Land Ordinance of 1784, Thomas Jefferson proposed a new state called "Pelisipia", to the south of the Ohio River, which would have included parts of present-day Eastern Kentucky and West Virginia; the river had great significance in the history of the Native Americans, as numerous civilizations formed along its valley. For thousands of years, Native Americans used the river as a major trading route, its waters connected communities. In the five centuries before European conquest, the Mississippian culture built numerous regional chiefdoms and major earthwork mounds in the Ohio Valley, such as Angel Mounds near Evansville, Indiana, as well as in the Mississippi Valley and the Southeast; the Osage, Omaha and Kaw lived in the Ohio Valley, but under pressure from the Iroquois to the northeast, migrated west of the Mississippi River in the 17th century to territory now defined as Missouri and Oklahoma.
The discovery and traversal of the Ohio River by Europeans admits of several possibilities, all in the latter half of the 17th century. Virginian Englishman Abraham Wood's trans-Appalachian expeditions between 1654 and 1664; the first person to traverse the length of the river, from the headwaters of the Allegheny to its mouth on the Mississippi, was a Dutch trader from New York, Arnout Viele, in 1692. In 1749, Great Britain established the Ohio Company to trade in the area. Exploration of the territory and trade with the Indians in the region near the Forks brought British colonials from both Pennsylvania and Virginia across the mountains, both colonies claimed the territory; the movement across the Allegheny Mountains of British settlers and the claims of the area near modern day Pittsburgh led to conflict with the French, who had forts in the Ohio River Valley. This conflict was called the Indian War. In 17
In structural engineering and construction, an eyebar is a straight bar of metal, with a hole at each end for fixing to other components. Eyebars are used in structures such as bridges, in settings in which only tension, never compression, is applied. Referred to as "pin - and eyebar construction" in instances where pins are being used. A closed eyebar will have a rectangular cross section of constant thickness throughout its length and a constant width for all but the ends; the ends will transition to a wider part, terminated by a rounded end. In the center of this end will be a hole which will receive a cylindrical pin, which may have provision to accept one or more nuts or bolts. If of round cross section the bar will be end-forged to create a head, flatted by additional forging; the head may be machined to a precise thickness and flatness. An alternative method for using round bar is to form a loop and to forge-weld or electrically weld the free end to the main bar. Open eyebars are not used in the cable anchorages of modern wire-cable suspension bridges.
This does not allow the wires to be looped over the eye, rather than requiring threading through a closed eye. The bars may be fabricated with pin holes that are undersized. If so, these are reamed in the field; this field reaming ensures that stresses will be uniformly distributed among the several bars forming the truss element or the chain link. Corrosion resistant treatment in the form of grease, white or red lead oil paste, or other water-excluding material may be added at the time of the assembly. Eyebars are used in portions of pin-jointed trusses where it can be established by engineering procedures that the bar will not be imposed with any stress other than tension under all expected conditions. Eyebars are used to supplement roof truss framing supports made of metal, they are placed as the struts for the trust, located next to the king joist. Eyebar links have long been used in suspension bridges with a number of eyebar links combed together to form a redundant structure; this use of eyebar places it in a chain linkage, holding a load based on tension rather than compression.
However, more modern low-redundancy chain link suspension spans fell into general disfavor as a result of the collapse of the Silver Bridge in 1967, which led to the deaths of 46 people. Eyebars may be forged, or cut from rolled plate. If round stock is used the eyes will be forged. Heat treatment will result in a fine-grained microscopic crystal structure, enhancing the strength of the bar. Excessive hardness may induce brittleness; the pins used to join bars will be heat treated to a degree of hardness exceeding that of the bars so that they will not shear under high stress. Original eyebars were formed from "piling" thin iron metal on top of one another and forging it together in a furnace. Once together the piece was hammered into a U shape over a die. To create the eye the heated bent iron was hammered into itself closing the gap and creating the eye shape.. This method created a quick and efficient way to create the bar, however would not structurally stay together after a certain point due to the piling method being ill heated or being defective.
New methods for eyebar creation involves the use of Steel casting both the eye and the bar together in the same mold which creates a more sound casting with less area for the bond to break apart. Newer methods of steel cutting such as laser / plasma / and water-jetting have created more efficient ways of creating steel items such as eyebars from steel plates. A strong laser is used to cut a programed design from steel; this method is quick and reduces down on waste, but requires additional sanding and finishing before use. Oxygen gas is funneled past an electrode creates an arch which can be channeled down into steel allowing the metal to be cut; this method for cutting only works on conductive metals. Similar to the laser, water-jet cutting utilizes a cutting machine but uses for the force of water to cut through the steel. Using water creates smoothed near finished cuts lowering production time. Eyebars were created during the early 1900's; the creation of the eyebar provided a simple solution to lessening the amount of steel needed in a bridge.
Using a pin and eye method less stress would theoretically be placed on the joining members. Issues occur for the following reason. A Bar not made properly from bad casting if Steel or not hammered properly if Iron; this error is evident in points where the head has snapped off from the bar or the had has cracked across from pin hole to exterior side. Eye bars. Consider the catastrophe of Silver Bridge, this was an instance where only 2 eyebars were paired together as supports in the chain, it was more common practice to use 4 eye bars pinned together in the instance where one eyebar failed 3 more would be able to split the load rather than just the single eyebar left. In the case of Silver bridge the remaining eye bar broke which caused the bridge to collapse. General wear. Like all metal Steel wears down over time; as a result the steel pins in the eyes become loose, as a result looses tension, which in turn compromises the integrity of the structure. Due to the technological advancements in creating eyebars Iron and old cast method of Steel eyebars are less common.
These older bridges however still need to be reviewed. Researchers like Dewey Walls, Jr. of the Union Pacific Rail Road have complied re