title: "Black-billed magpie" content: West. Today black-billed magpies remain relatively tame in areas where they are not persecuted. However, they become very wary in areas where they are often shot at or disturbed. Especially during the first half of the 20th century, black-billed magpies were considered detrimental to game-bird populations (they sometimes steal bird eggs) and domestic stock (they sometimes peck at sores on cattle), and were systematically trapped or shot. Bounties of one cent per egg or two cents per head were offered in many states. In Idaho the death toll eventually amounted to an estimated 150,000. In 1933, 1,033 magpies were shot


title: "Black-billed magpie" content: in Washington's Okanogan valley by two teams of bounty hunters. Many magpies also died from eating poison set out for coyotes and other predators. If regularly disturbed at the nest, magpie pairs will eventually either move the eggs or abandon the clutch altogether, but in the first instance they will defend the nest aggressively. Biologists who have climbed nest trees to measure magpie eggs have reported that the parents recognized them personally on subsequent days and started to mob them, overlooking other people in the vicinity. Many suburban songbird lovers dislike magpies because of their reputation for stealing eggs, but


title: "Black-billed magpie" content: studies have shown that eggs make up only a small proportion of what magpies feed on during the reproductive season. In England, the European magpie also has a reputation for taking eggs, and yet when density of magpie populations increases, songbird density does not decrease; on the contrary, it increases too. In the United States, black-billed magpies are protected under the Migratory Bird Treaty Act, but "[a] Federal permit shall not be required to control ... [magpies] when found committing or about to commit depredations upon ornamental or shade trees, agricultural crops, livestock, or wildlife, or when concentrated in such


title: "Black-billed magpie" content: numbers and manner as to constitute a health hazard or other nuisance". State or local regulations may limit or prohibit killing these birds as well. The species is not threatened and in some areas it has benefited from forest fragmentation and agricultural developments. Like many corvids, however, it is susceptible to West Nile virus. Black-billed magpie The black-billed magpie ("Pica hudsonia"), also known as the American magpie, is a bird in the crow family that inhabits the western half of North America, from Colorado, to southern coastal Alaska to northern California, northern Nevada, northern Arizona, northern New Mexico, central Kansas,


title: "Metric tensor" content: otherwise moves freely, with constant momentum, within the manifold. In analogy with the case of surfaces, a metric tensor on an -dimensional paracompact manifold gives rise to a natural way to measure the -dimensional volume of subsets of the manifold. The resulting natural positive Borel measure allows one to develop a theory of integrating functions on the manifold by means of the associated Lebesgue integral. A measure can be defined, by the Riesz representation theorem, by giving a positive linear functional on the space of compactly supported continuous functions on . More precisely, if is a manifold with a (pseudo-)Riemannian


title: "Eurasian magpie" content: Eurasian magpie The Eurasian magpie or common magpie ("Pica pica") is a resident breeding bird throughout northern part of Eurasian continent. It is one of several birds in the crow family designated magpies, and belongs to the Holarctic radiation of "monochrome" magpies. In Europe, "magpie" is used by English speakers as a synonym for the European magpie: the only other magpie in Europe is the Iberian magpie ("Cyanopica cooki"), which is limited to the Iberian Peninsula. The Eurasian magpie is one of the most intelligent birds, and it is believed to be one of the most intelligent of all non-human


title: "Eurasian magpie" content: animals. The expansion of its nidopallium is approximately the same in its relative size as the brain of chimpanzees, orangutans and humans. The magpie was described and illustrated by Swiss naturalist Conrad Gessner in his "Historiae animalium" of 1555. In 1758 Linnaeus included the species in the 10th edition of his "Systema Naturae" under the binomial name "Corvus pica". The magpie was moved to a separate genus "Pica" by the French zoologist Mathurin Jacques Brisson in 1760. "Pica" is the Classical Latin word for this magpie. The Eurasian magpie is almost identical in appearance to the North American black-billed magpie


title: "Eurasian magpie" content: ("Pica hudsonia") and at one time the two species were considered to be conspecific. In 2000, the American Ornithologists' Union decided to treat the black-billed magpie as a separate species based on studies of the vocalization and behaviour that indicated that the black-billed magpie was closer to the yellow-billed magpie ("Pica nuttalli") than to the Eurasian magpie. The gradual clinal variation over the large geographic range and the intergradation of the different subspecies means that the geographical limits, and acceptance of the various subspecies, vary between authorities. The International Ornithological Congress recognises six subspecies ("P. p. hemileucoptera" is included in


title: "Eurasian magpie" content: "P. p. bactriana"): Others now considered as distinct species: An analysis of mitochondrial DNA sequences published in 2003 confirmed that the black-billed magpie and the yellow-billed magpie were closely related to each other. The study also found that magpies in Korea (described as "P. p. serica") are as different from the nominate subspecies as they are to the North America magpie species. These results imply that the species "Pica pica" is not monophyletic. A more recent study using both mitochondrial and nuclear DNA found that magpies in east and northeast China are genetically very similar to each other but differ


title: "Eurasian magpie" content: from those in northwest China and Spain. Magpies were originally known as simply "pies". This comes from a proto-Indoeuropean root meaning "pointed", in reference to either the beak or the tail. The prefix "mag" dates from the 16th century and comes from the short form of the given name Margaret, which was once used to mean women in general (as Joe or Jack is used for men today); the pie's call was considered to sound like the idle chattering of a woman, and so it came to be called the "Mag pie". "Pie" as a term for the bird dates


title: "Eurasian magpie" content: to the 13th century, and the word "pied", first recorded in 1552, became applied to other birds that resembled the magpie in having black-and-white plumage. The adult male of the nominate subspecies, "P. p. pica", is in length, of which more than half is the tail. The wingspan is . The head, neck and breast are glossy black with a metallic green and violet sheen; the belly and scapulars (shoulder feathers) are pure white; the wings are black glossed with green or purple, and the primaries have white inner webs, conspicuous when the wing is open. The graduated tail is


title: "Eurasian magpie" content: black, glossed with green and reddish purple. The legs and bill are black; the iris is dark brown. The plumage of the sexes is similar but females are slightly smaller. The tail feathers of both sexes are quite long, about 12–28 cm long. Males of the nominate subspecies weigh while females weigh . The young resemble the adults, but are at first without much of the gloss on the sooty plumage. The young have the malar region pink, and somewhat clear eyes. The tail is much shorter than the adults. The subspecies differ in their size, the amount of white


title: "Eurasian magpie" content: on their plumage and the colour of the gloss on their black feathers. The Asian subspecies "P. p. bactriana" has more extensive white on the primaries and a prominent white rump. Adults undergo an annual complete moult after breeding. Moult begins in June or July and ends in September or October. The primary flight feathers are replaced over a period of three months. Juvenile birds undergo a partial moult beginning about one month later than the adult birds in which their body feathers are replaced but not those of the wings or the tail. Eurasian magpies have a well-known call.


title: "Eurasian magpie" content: It is a choking chatter "chac-chac" or a repetitive "chac-chac-chac-chac". The young also emit the previous call, although they also emit an acute call similar to a "Uik Uik", which may resemble the barking of a small dog. Both adults and young can emit a kind of hiss barely noticeable from afar. The range of the magpie extends across temperate Eurasia from Spain and Ireland in the west to the Kamchatka Peninsula. The species has been introduced in Japan on the island of Kyushu. The preferred habit is open countryside with scattered trees and magpies are normally absent from treeless


title: "Eurasian magpie" content: areas and dense forests. They sometimes breed at high densities in suburban settings such as parks and gardens. They can often be found close to the centre of cities. Magpies are normally sedentary and spend winters close to their nesting territories but birds living near the northern limit of their range in Sweden, Finland and Russia can move south in harsh weather. Some magpies breed after their first year, while others remain in the non-breeding flocks and first breed in their second year. They are monogamous, and the pairs often remain together from one breeding season to the next. They


title: "Eurasian magpie" content: generally occupy the same territory on successive years. Mating takes place in spring. In the courtship display, males rapidly raise and depress their head feathers, uplift, open and close their tails like fans, and call in soft tones quite distinct from their usual chatter. The loose feathers of the flanks are brought over the primaries, and the shoulder patch is spread so the white is conspicuous, presumably to attract females. Short buoyant flights and chases follow. Magpies prefer tall trees for their bulky nest, firmly attaching them to a central fork in the upper branches. A framework of the sticks


title: "Eurasian magpie" content: is cemented with earth and clay, and a lining of the same is covered with fine roots. Above is a stout though loosely built dome of prickly branches with a single well-concealed entrance. These huge nests are conspicuous when the leaves fall. Where trees are scarce, though even in well-wooded country, nests are at times built in bushes and hedgerows. In Europe, clutches are typically laid in April, and usually contain five or six eggs, but clutches with as few as three and as many as ten have been recorded. The eggs are laid in early morning, usually at daily


title: "Eurasian magpie" content: intervals. On average, the eggs of the nominate species measure and weigh . Small for the size of the bird, they are typically pale blue-green, with close specks and spots of olive brown, but show much variation in ground and marking. The eggs are incubated for 21–22 days by the female, who is fed on the nest by the male. The chicks are altricial, hatching nearly naked with closed eyes. They are brooded by the female for the first 5–10 days and fed by both parents. Initially the parents eat the faecal sacs of the nestlings, but as the chicks


title: "Eurasian magpie" content: grow larger, they defecate on the edge of the nest. The nestlings open their eyes 7 to 8 days after hatching. Their body feathers start to appear after around 8 days and the primary wing feathers after 10 days. For several days before they are ready to leave the nest, the chicks clamber around the nearby branches. They fledge at around 27 days. The parents then continue to feed the chicks for several more weeks. They also protect the chicks from predators, as their ability to fly is poor, making them vulnerable. On average, only 3 or 4 chicks survive


title: "Eurasian magpie" content: to fledge successfully. Some nests are lost to predators, but an important factor causing nestling mortality is starvation. Magpie eggs hatch asynchronously, and if the parents have difficulty finding sufficient food, the last chicks to hatch are unlikely to survive. Only a single brood is reared, unless disaster overtakes the first clutch. A study conducted near Sheffield in Britain, using birds with coloured rings on their legs, found that only 22% of fledglings survived their first year. For subsequent years, the survival rate for the adult birds was 69%, implying that for those birds that survive the first year, the


title: "Eurasian magpie" content: average total lifespan was 3.7 years. The maximum age recorded for a magpie is 21 years and 8 months for a bird from near Coventry in England that was ringed in 1925 and shot in 1947. The magpie is omnivorous, eating young birds and eggs, small mammals, insects, scraps and carrion, acorns, grain, and other vegetable substances. The Eurasian magpie is believed not only to be among the most intelligent of birds but among the most intelligent of all animals. Along with the jackdaw, the Eurasian magpie's nidopallium is approximately the same relative size as those in chimpanzees and humans,


title: "Eurasian magpie" content: significantly larger than the gibbon's. Like other corvids, such as ravens and crows, their total brain-to-body mass ratio is equal to most great apes and cetaceans. A 2004 review suggests that the intelligence of the corvid family to which the Eurasian magpie belongs is equivalent to that of great apes (chimpanzees, orangutans, and gorillas) in terms of social cognition, causal reasoning, flexibility, imagination and prospection. Magpies have been observed engaging in elaborate social rituals, possibly including the expression of grief. Mirror self-recognition has been demonstrated in European magpies, making them one of only a few species to possess this capability.


title: "Eurasian magpie" content: The cognitive abilities of the Eurasian magpie are regarded as evidence that intelligence evolved independently in both corvids and primates. This is indicated by tool use, an ability to hide and store food across seasons, episodic memory, using their own experience to predict the behavior of conspecifics. Another behaviour exhibiting intelligence is cutting their food in correctly sized proportions for the size of their young. In captivity, magpies have been observed counting up to get food, imitating human voices, and regularly using tools to clean their own cages. In the wild, they organise themselves into gangs and use complex strategies


title: "Eurasian magpie" content: hunting other birds and when confronted by predators. Marc Bekoff, at the University of Colorado, argues that Eurasian magpies are capable of feeling complex emotions, including grief. The Eurasian magpie has an extremely large range. The European population is estimated to be between 7.5 and 19 million breeding pairs. Allowing for the birds breeding in other continents, the total population is estimated to be between 46 and 228 million individuals. The population trend in Europe has been stable since 1980. There is no evidence of any serious overall decline in numbers, so the species is classified by the International Union


title: "Eurasian magpie" content: for Conservation of Nature as being of Least Concern. In Europe, magpies have been historically demonized by humans, mainly as a result of superstition and myth. The bird has found itself in this situation mainly by association, says Steve Roud: "Large blackbirds, like crows and ravens, are viewed as evil in British folklore and white birds are viewed as good". In European folklore, the magpie is associated with a number of superstitions surrounding its reputation as an omen of ill fortune. In the 19th century book, "A Guide to the Scientific Knowledge of Things Familiar", a proverb concerning magpies is


title: "Eurasian magpie" content: recited: "A single magpie in spring, foul weather will bring". The book further explains that this superstition arises from the habits of pairs of magpies to forage together only when the weather is fine. In Scotland, a magpie near the window of the house is said to foretell death. An English tradition holds that a single magpie be greeted with a salutation in order to ward off the bad luck it may bring. A greeting might take the form of saying the words ‘Good morning, Mr Magpie, how are Mrs Magpie and all the other little magpies?’ In Britain and


title: "Eurasian magpie" content: Ireland, a widespread traditional rhyme, "One for Sorrow", records the myth (it is not clear whether it has been seriously believed) that seeing magpies predicts the future, depending on how many are seen. There are many regional variations on the rhyme, which means that it is impossible to give a definitive version. In Italian, British and French folklore, magpies are believed to have a penchant for picking up shiny items, particularly precious stones or metal objects. Rossini's opera "La gazza ladra" and "The Adventures of Tintin" comic "The Castafiore Emerald" are based on this theme. However, one recent research study


title: "Eurasian magpie" content: has cast doubt on the veracity of this belief. In Bulgarian, Czech, German, Hungarian, Polish, Russian, Slovak and Swedish folklore the magpie is seen as a thief. In Sweden, it is further associated with witchcraft. In Norway, a magpie is considered cunning and thievish, but also the bird of huldra, the underground people. Magpies have been attacked for their role as predators, which includes eating other birds' eggs and their young. However, scientific studies have contradicted the view that they affect total song-bird populations, finding "no evidence of any effects of [magpie] predator species on songbird population growth rates. We


title: "Eurasian magpie" content: therefore had no indication that predators had a general effect on songbird population growth rates". Other studies have found that songbird populations increased in places where magpie populations were high and that they do not have a negative impact on the total song-bird population. Eurasian magpie The Eurasian magpie or common magpie ("Pica pica") is a resident breeding bird throughout northern part of Eurasian continent. It is one of several birds in the crow family designated magpies, and belongs to the Holarctic radiation of "monochrome" magpies. In Europe, "magpie" is used by English speakers as a synonym for the European


title: "Livingston, Guatemala" content: wealth. Timber contracts were granted to multinational companies such as Murphy Pacific Corporation from California, which invested US$30 million for the colonization of southern Petén and Alta Verapaz, and formed the North Impulsadora Company. Colonization of the area was made through a process by which inhospitable areas of the Franja Transversal del Norte (FTN) were granted to native peasants. In 1964, the National Institute for Agrarian Transformation (INTA) defined the geography of the FTN as the northern part of the departments of Huehuetenango, Quiché , Alta Verapaz and Izabal and that same year priests of the Maryknoll order and the


title: Catamaran content: Catamaran A catamaran () (informally, a "cat") is a multi-hulled watercraft featuring two parallel hulls of equal size. It is a geometry-stabilized craft, deriving its stability from its wide beam, rather than from a ballasted keel as with a monohull sailboat. Catamaran is from a Tamil word "Kattumaram" which means logs tied together. Catamarans typically have less hull volume, higher displacement, and shallower draft (draught) than monohulls of comparable length. The two hulls combined also often have a smaller hydrodynamic resistance than comparable monohulls, requiring less propulsive power from either sails or motors. The catamaran's wider stance on the water


title: Catamaran content: can reduce both heeling and wave-induced motion, as compared with a monohull, and can give reduced wakes. Catamarans range in size from small (sailing or rowing vessels) to large (naval ships and car ferries). The structure connecting a catamaran's two hulls ranges from a simple frame strung with webbing to support the crew to a bridging superstructure incorporating extensive cabin and/or cargo space. Catamarans from Polynesia and Maritime Southeast Asia became the inspiration for modern catamarans. Catamaran-type vessels were first developed as early as 1500 BCE by the Polynesian peoples. These early examples were likely related to outrigger canoes and


title: Catamaran content: consisted of two canoes bound together with a wooden frame, sometimes accompanied by a sail. Despite their simplicity they were nonetheless effective, allowing seafaring Polynesians to voyage to distant Pacific islands. Catamarans were seldom constructed in the West before the 19th century, but they were in wide use as early as the 5th century by the Tamil people of Tamil Nadu, South India. The word "catamaran" is derived from the Tamil word, "kattumaram" (கட்டுமரம்), which means "logs bound together." The 17th-century English adventurer and privateer William Dampier encountered the Tamil people of southeastern India during his first circumnavigation of the


title: Catamaran content: globe. He was the first to write in English about the watercraft he observed in use there. In his 1697 account of his trip, "A New Voyage Round the World", he wrote, The first documented example of double-hulled craft in Europe was designed by William Petty in 1662 to sail faster, in shallower waters, in lighter wind, and with fewer crew than other vessels of the time. However, the unusual design met with skepticism and was not a commercial success. The design remained relatively unused in the West for almost 160 years until the early 19th-century, when the Englishman Mayflower


title: Catamaran content: F. Crisp built a two-hulled merchant ship in Rangoon, Burma. The ship was christened "Original". Crisp described it as "a fast sailing fine sea boat; she traded during the monsoon between Rangoon and the Tenasserim Provinces for several years". Later that century, the American Nathanael Herreshoff constructed a double-hulled sailing boat of his own design (US Pat. No. 189,459). The craft, "Amaryllis", raced at her maiden regatta on June 22, 1876, and performed exceedingly well. Her debut demonstrated the distinct performance advantages afforded to catamarans over the standard monohulls. It was as a result of this event, the Centennial Regatta


title: Catamaran content: of the New York Yacht Club, that catamarans were barred from regular sailing classes, and this remained the case until the 1970s. In 1936 Eric de Bisschop built a Polynesian "double canoe" in Hawaii and sailed it home to a hero's welcome in France. In 1939, he published his experiences in a book, "Kaimiloa", which was translated into English in 1940. The Prout Brothers, Roland and Francis, experimented with catamarans in 1949 and converted their 1935 boat factory in Canvey Island, Essex (England), to catamaran production in 1954. Their Shearwater catamarans won races easily against the monohulls. "Yellow Bird," a


title: Catamaran content: 1956-built Shearwater, raced successfully by Francis Prout in the 1960s, is in the collection of the National Maritime Museum Cornwall. In the mid-twentieth century, beachcats became a widespread category of sailing catamarans, owing to their ease of launching and mass production. In California, a maker of surfboards, Hobie Alter, produced the Hobie 14 in 1967, and two years later the larger and even more successful Hobie 16. As of 2016, the Hobie 16 was still being produced with more than 100,000 having been manufactured. The Tornado catamaran was designed by three Englishmen for a crew of two in 1967 as


title: Catamaran content: an Olympic catamaran candidate. At the Olympic Catamaran Trials of the International Yacht Racing Union, IYRU, it outperformed the other challengers for the role and was selected for the multihull discipline in the Olympic Games from 1976 through 2008. It was redesigned in 2000 and remains one of the fastest double-handed catamaran models. Australia became the site of builders of large transport catamarans—Incat in 1977 and Austal in 1988—each building civilian ferries and naval vessels. The largest ship ever built in terms of gross tonnage, the "Pioneering Spirit", incorporates a catamaran design. Catamarans have two distinct primary performance characteristics that


title: Catamaran content: distinguish them from displacement monohull vessels: lower resistance to passage through the water and greater stability (initial resistance to capsize). Choosing between a monohull and catamaran configuration includes considerations of carrying capacity, speed, and efficiency. At low to moderate speeds, a lightweight catamaran hull experiences resistance to passage through water that is approximately proportional to the square of its speed. A displacement monohull, by comparison, experiences resistance that is at least the cube of its speed. This means that a catamaran would require four times the power in order to double its speed, whereas a monohull would require eight times


title: Catamaran content: the power to double its speed, starting at a slow speed. For powered catamarans, this implies smaller power plants (although two are typically required). For sailing catamarans, low forward resistance allows the sails to derive power from attached flow, their most efficient mode—analogous to a wing—leading to the use of wingsails in racing craft. Catamarans rely primarily on form stability to resist heeling and capsize. Comparison of heeling stability of a rectangular-cross section monohull of beam, "B", compared with two catamaran hulls of width "B"/2, separated by a distance, 2×"B", determines that the catamaran has an initial resistance to heeling


title: Catamaran content: that is seven times that of the monohull. Compared with a monohull, a cruising catamaran sailboat has a high initial resistance to heeling and capsize—a fifty-footer requires four times the force to initiate a capsize than an equivalent monohull. One measure of the trade-off between speed and carrying capacity is the displacement Froude number (Fn), compared with "calm water transportation efficiency". Fn applies when the waterline length is too speed-dependent to be meaningful—as with a planing hull. It uses a reference length, the cubic root of the volumetric displacement of the hull, "V", where "u" is the relative flow velocity


title: Catamaran content: between the sea and ship, and "g" is acceleration due to gravity: "Calm water transportation efficiency" of a vessel is proportional to the full-load displacement and the maximum calm-water speed, divided by the corresponding power required. Large merchant vessels have a Fn between one and zero, whereas higher-performance powered catamarans may approach 2.5—denoting a "higher speed" per unit volume for "catamarans". Each type of vessel has a corresponding calm water transportation efficiency, with large transport ships being in the range of 100–1,000, compared with 11-18 for transport catamarans—denoting a "higher efficiency" per unit of payload for "monohulls". Sailing catamarans have


title: Catamaran content: been noted for incorporating technological advances over traditional monohull craft. These include foils that lift racing catamarans out of the water, capacious and stable cruising vessels, and racers that have achieved average speeds on the open ocean, comparable to much larger vessels. Recreational and sport catamarans typically are designed to have a crew of two and be launched and landed from a beach. Most have a trampoline on the bridging structure, a rotating mast and full-length battens on the mainsail. Performance versions often have trapezes to allow the crew to hike out and counterbalance capsize forces during strong winds on


title: Catamaran content: certain points of sail. For the 33rd America's Cup, both the defender and the challenger built long multihulls. Société Nautique de Genève, defending with team Alinghi, sailed a catamaran. The challenger, BMW Oracle Racing, used a trimaran, replacing its soft sail rig with a towering wing sail—the largest sailing wing ever built. In the waters off Valencia, Spain in February 2010, the BMW Oracle Racing trimaran with its powerful wing sail proved to be superior. This represented a break from the traditional monohulls that had always been sailed in previous America's Cup series. On San Francisco Bay, the 2013 America's


title: Catamaran content: Cup was sailed in long AC72 catamarans (craft set by the rules for the 2013 America's Cup). Each yacht employed hydrofoils and a wing sail. The regatta was won 9-8 by Oracle Team USA against the challenger, Emirates Team New Zealand, in fifteen matches because Oracle Team USA had started the regatta with a two-point penalty. Cruising sailors must make trade-offs among volume, useful load, speed, and cost in choosing a boat. Choosing a catamaran offers increased speed at the expense of reduced load per unit of cost. Howard and Doane describe the following tradeoffs between cruising monohulls and catamarans:


title: Catamaran content: A long-distance, offshore cruising monohull may be as short as for a given crew complement and supporting supplies, whereas a cruising catamaran would need to be to achieve the same capacity. In addition to greater speed, catamarans draw less water than do monohulls—little as —and are easier to beach. Catamarans are harder to tack and take up more space in a marina. Cruising catamarans entail added expense for having two engines and two rudders. Tarjan adds that cruising catamarans boats can maintain a comfortable per day passage, with the racing versions recording well over per day. In addition, they do


title: Catamaran content: not heel more than 10-12 degrees, even at full speed on a reach. Yachting has seen the development of multihulls over in length. "The Race" helped precipitate this trend; it was a circumnavigation challenge which departed from Barcelona, Spain, on New Year's Eve, 2000. Because of the prize money and prestige associated with this event, four new catamarans (and two highly modified ones) over in length were built to compete. The largest, "PlayStation", owned by Steve Fossett, was long and had a mast which was above the water. Virtually all of the new mega-cats were built of pre-preg carbon fiber


title: Catamaran content: for strength and the lowest possible weight. The top speeds of these boats can approach . The Race was won by the -long catamaran "Club Med" skippered by Grant Dalton. It went round the globe in 62 days at an average speed of . A catamaran configuration fills a niche for powered vessels, where speed and sea-kindliness is favored over bulk capacity. In larger vessels, this niche favors car ferries and military vessels for patrol or operation in the littoral zone. Two advances over the traditional catamaran are the "small-waterplane-area twin hull" (SWATH) and the "wave-piercing" configuration—the latter having become


title: Catamaran content: a widely favored design. An outgrowth of the popularity of cruising sailing catamarans are powered catamarans, which share many of the amenities found in a sail cruising catamaran. The saloon typically spans two hulls wherein are found the staterooms and engine compartments. As with sailing catamarans, this configuration minimizes boat motion in a seaway. The Swiss-registered wave-piercing catamaran, "Tûranor PlanetSolar", which was launched in March 2010, is the world's largest solar powered boat. It completed a circumnavigation of the globe in 2012. The 1970s saw the introduction of catamarans as a high-speed ferries, as pioneered by Westermoen Hydrofoil in Mandal,


title: Catamaran content: Norway, which launched the Westamaran design in 1973. The "Stena Voyager" was an example of a large, fast ferry, typically traveling at a speed of , although it was capable of doing over . Military Sealift Command currently operates several Expeditionary Fast Transport catamarans which are owned by the U.S. Navy. These are employed for the high speed transport of military cargo and are able to get into shallow ports due to their small draft. The "Makar"-class is a class of two large catamaran-hull survey ships built for the Indian Navy. As of 2012, one vessel, INS Makar (J31), was


title: Catamaran content: in service and the second was under construction. First launched in 2004 at Shanghai, the Houbei class missile boat of the People's Liberation Army Navy (PLAN) utilizes a catamaran hull designed to accommodate the vessel's stealth features. The small-waterplane-area twin hull (SWATH) configuration reduces wave-generating resistance by moving displacement volume below the waterline, using a pair of tubular, submarine-like hulls, connected by pylons to the bridge deck with a narrow waterline cross-section. The submerged hulls are minimally affected by waves. The SWATH form was invented by Canadian Frederick G. Creed, who presented his idea in 1938 and was later awarded


title: Catamaran content: a British patent for it in 1946. It was first used in the 1960s and 1970s as an evolution of catamaran design for use as oceanographic research vessels or submarine rescue ships. In 1990, the US Navy commissioned the construction of a SWATH ship to test the configuration. SWATH vessels compare with conventional powered catamarans of equivalent size, as follows: Wave-piercing catamarans employ a low-buoyancy bow on each hull that is pointed at the water line and rises aft, up to a level, to allow each hull to pierce waves, rather than ride over them. This allows higher speeds through


title: Catamaran content: waves than for a conventional catamaran. They are distinguished from SWATH catamarans, in that the buoyant part of the hull is not tubular. The spanning bridge deck may be configured with some of the characteristics of a normal V-hull, which allows it to penetrate the crests of waves. Wave-piercing catamaran designs have been employed for yachts, passenger ferries, and military vessels. The catamarans for whitewater sports are widely spread in post-Soviet countries. They consists of two inflatable hulls connected with a lattice scaffold. The frame of the tourist catamaran can be made of both - aluminum (duralumin) pipes, and from


title: Catamaran content: felled tree trunks. The inflatable part has two layers - airtight balloon with inflation holes and shell made of dense tissue, protecting the balloon from mechanical damage. Advantages of such catamarans are light weight, compactness and convenience in transportation (the whole product is packed in one pack-backpack, suitable for air traffic standards), the speed of assembly (10-15 minutes for the inflation). Landing on such a catamaran can be a raft-type, as well as a sports knee-type. Catamaran A catamaran () (informally, a "cat") is a multi-hulled watercraft featuring two parallel hulls of equal size. It is a geometry-stabilized craft, deriving


title: "Ludwig Beck" content: 1931–1932, he led the group of army writers, at the Department of the Army ("Truppenamt") which published the German Army Operations Manual entitled "Truppenführung". The first section was promulgated in 1933 and the second section in 1934. A modified version is still in use today by the Federal German Army. He was promoted to the rank of "Generalleutnant" in 1932 and, two years later, he replaced General Wilhelm Adam as chief of the "Truppenamt", the camouflaged General Staff (the Treaty of Versailles explicitly forbade the existence of the General Staff). In September–October 1930, Beck was a leading defence witness at


title: "Ludwig Beck" content: Walther von Brauchitsch with memoranda opposing "Fall Grün" (Case Green), the plan for a war with Czechoslovakia. In the first of his memos, on 5 May 1938, Beck argued that the Sino-Japanese War meant Japan would be unable to come to Germany's aid, that the French Army was the best fighting force in Europe, and that Britain was certain to intervene on the side of France should Germany attack Czechoslovakia. In his May memo, Beck argued that Hitler's assumptions about France, made in the Hossbach Memorandum of 1937, were mistaken, and stated his belief that France "wishes for peace or,


title: "Ray Stannard Baker" content: 1908 after the 1906 Atlanta Race Riot got him involved, Baker published the book "Following the Color Line: An Account of Negro Citizenship in the American Democracy", becoming the first prominent journalist to examine America's racial divide; it was extremely successful. Sociologist Rupert Vance says it is: He followed up that work with numerous articles in the following decade. In 1910, he moved to the town of Amherst, Massachusetts. In 1912 Baker supported the presidential candidacy of Woodrow Wilson, which led to a close relationship between the two men, and in 1918 Wilson sent Baker to Europe to study the


title: "USS Minnesota (BB-22)" content: been laid by the U-boat "U-117", which inflicted serious damage but caused no casualties. The explosion tore a gaping hole in the hull from frame 5 to frame 16, and from the keel to the bottom edge of the armor belt. The bow flooded, but the repaired bulkheads prevented the flooding from spreading. Reduced to a speed of , "Minnesota" made it back to the Philadelphia Navy Yard where repairs were effected. The work lasted for five months, by which time Germany had signed the Armistice that ended the war. On 11 March 1919, "Minnesota" returned to service with the


title: "Steam locomotive" content: Steam locomotive A steam locomotive is a type of railway locomotive that produces its pulling power through a steam engine. These locomotives are fueled by burning combustible material – usually coal, wood, or oil – to produce steam in a boiler. The steam moves reciprocating pistons which are mechanically connected to the locomotive's main wheels (drivers). Both fuel and water supplies are carried with the locomotive, either on the locomotive itself or in wagons (tenders) pulled behind. Steam locomotives were first developed in Great Britain during the early 19th century and used for railway transport until the middle of the


title: "Steam locomotive" content: 20th century. The first steam locomotive, made by Richard Trevithick, first operated on 21 February 1804, three years after the road locomotive he made in 1801. The first commercially successful steam locomotive was created in 1812–13 by John Blenkinsop. Built by George Stephenson and his son Robert's company Robert Stephenson and Company, the "Locomotion" No. 1 is the first steam locomotive to carry passengers on a public rail line, the Stockton and Darlington Railway in 1825. George also built the first public inter-city railway line in the world to use locomotives, the Liverpool and Manchester Railway, which opened in 1830.


title: "Steam locomotive" content: Stephenson established his company as the pre-eminent builder of steam locomotives for railways in the United Kingdom, the United States, and much of Europe. In the 20th century, Chief Mechanical Engineer of the London and North Eastern Railway (LNER) Nigel Gresley designed some of the most famous locomotives, including the "Flying Scotsman", the first steam locomotive officially recorded over 100 mph in passenger service, and a LNER Class A4, 4468 "Mallard", which still holds the record for being the fastest steam locomotive in the world (126 mph). From the early 1900s steam locomotives were gradually superseded by electric and diesel


title: "Steam locomotive" content: locomotives, with railways fully converting to electric and diesel power beginning in the late 1930s. The majority of steam locomotives were retired from regular service by the 1980s, though several continue to run on tourist and heritage lines. The earliest railways employed horses to draw carts along rail tracks. In 1784, William Murdoch, a Scottish inventor, built a small-scale prototype of a steam road locomotive in Birmingham. A full-scale rail steam locomotive was proposed by William Reynolds around 1787. An early working model of a steam rail locomotive was designed and constructed by steamboat pioneer John Fitch in the US


title: "Steam locomotive" content: during 1794. His steam locomotive used interior bladed wheels guided by rails or tracks. The model still exists at the Ohio Historical Society Museum in Columbus. The authenticity and date of this locomotive is disputed by some experts and a workable steam train would have to await the invention of the high-pressure steam engine by Richard Trevithick, who pioneered the use of steam locomotives. The first full-scale working railway steam locomotive, was the gauge "Coalbrookdale Locomotive", built by Trevithick in 1802. It was constructed for the Coalbrookdale ironworks in Shropshire in the United Kingdom though no record of it working


title: "Steam locomotive" content: there has survived. On 21 February 1804, the first recorded steam-hauled railway journey took place as another of Trevithick's locomotives hauled a train along the tramway from the Pen-y-darren ironworks, near Merthyr Tydfil, to Abercynon in South Wales. Accompanied by Andrew Vivian, it ran with mixed success. The design incorporated a number of important innovations that included using high-pressure steam which reduced the weight of the engine and increased its efficiency. Trevithick visited the Newcastle area in 1804 and had a ready audience of colliery (coal mine) owners and engineers. The visit was so successful that the colliery railways in


title: "Steam locomotive" content: north-east England became the leading centre for experimentation and development of the steam locomotive. Trevithick continued his own steam propulsion experiments through another trio of locomotives, concluding with the "Catch Me Who Can" in 1808. In 1812, Matthew Murray's successful twin-cylinder rack locomotive "Salamanca" first ran on the edge-railed rack-and-pinion Middleton Railway. Another well-known early locomotive was "Puffing Billy", built 1813–14 by engineer William Hedley. It was intended to work on the Wylam Colliery near Newcastle upon Tyne. This locomotive is the oldest preserved, and is on static display in the Science Museum, London. In 1825 George Stephenson built "Locomotion


title: "Steam locomotive" content: No. 1" for the Stockton and Darlington Railway, north-east England, which was the first public steam railway in the world. In 1829, his son Robert built in Newcastle "The Rocket" which was entered in and won the Rainhill Trials. This success led to the company emerging as the pre-eminent builder of steam locomotives used on railways in the UK, US and much of Europe. The Liverpool and Manchester Railway opened a year later making exclusive use of steam power for passenger and goods trains. Many of the earliest locomotives for American railroads were imported from Great Britain, including first the


title: "Steam locomotive" content: "Stourbridge Lion" and later the "John Bull" (still the oldest operable engine-powered vehicle in the United States of any kind, as of 1981) however a domestic locomotive-manufacturing industry was quickly established. The Baltimore and Ohio Railroad's "Tom Thumb" in 1830, designed and built by Peter Cooper, was the first US-built locomotive to run in America, although it was intended as a demonstration of the potential of steam traction, rather than as a revenue-earning locomotive. The "DeWitt Clinton" was also built in the 1830s. The first railway service outside the United Kingdom and North America was opened in 1829 in France


title: "Steam locomotive" content: between Saint-Etienne and Lyon. Then on 5 May 1835 the first line in Belgium linked Mechelen and Brussels. The locomotive was named "The Elephant". In Germany, the first working steam locomotive was a rack-and-pinion engine, similar to the "Salamanca", designed by the British locomotive pioneer John Blenkinsop. Built in June 1816 by Johann Friedrich Krigar in the Royal Berlin Iron Foundry ("Königliche Eisengießerei" zu Berlin), the locomotive ran on a circular track in the factory yard. It was the first locomotive to be built on the European mainland and the first steam-powered passenger service; curious onlookers could ride in the


title: "Steam locomotive" content: attached coaches for a fee. It is portrayed on a New Year's badge for the Royal Foundry dated 1816. Another locomotive was built using the same system in 1817. They were to be used on pit railways in Königshütte and in Luisenthal on the Saar (today part of Völklingen), but neither could be returned to working order after being dismantled, moved and reassembled. On 7 December 1835 the "Adler" ran for the first time between Nuremberg and Fürth on the Bavarian Ludwig Railway. It was the 118th engine from the locomotive works of Robert Stephenson and stood under patent protection.


title: "Steam locomotive" content: In 1837, the first steam railway started in Austria on the Emperor Ferdinand Northern Railway between Vienna-Floridsdorf and Deutsch-Wagram. The oldest continually working steam engine in the world also runs in Austria: the GKB 671 built in 1860, has never been taken out of service, and is still used for special excursions. In 1838, the third steam locomotive to be built in Germany, the "Saxonia", was manufactured by the "Maschinenbaufirma Übigau" near Dresden, built by Prof. Johann Andreas Schubert. The first independently designed locomotive in Germany was the "Beuth", built by August Borsig in 1841. The first locomotive produced by


title: "Steam locomotive" content: Henschel-Werke in Kassel, the "Drache", was delivered in 1848. The first steam locomotives operating in Italy were the "Bayard" and the "Vesuvio", running on the Napoli-Portici line, in the Kingdom of the Two Sicilies. The first railway line over Swiss territory was the Strasbourg–Basle line opened in 1844. Three years later, in 1847, the first fully Swiss railway line, the "Spanisch Brötli Bahn", from Zürich to Baden was opened. The fire-tube boiler was standard practice for steam locomotives and although other types of boiler were evaluated they were not widely used except for 1000 locomotives in Hungary which used the


title: "Steam locomotive" content: water-tube Brotan boiler. A boiler consists of a firebox where the fuel is burned, a barrel where water is turned into steam and a smokebox which is kept at a slightly lower pressure than outside the firebox. Solid fuel, such as wood, coal or coke, is thrown into the firebox through a door by a fireman, onto a set of grates which hold the fuel in a bed as it burns. Ash falls through the grate into an ashpan. If oil is used as the fuel, a door is needed for adjusting the air flow, maintaining the firebox, and cleaning


title: "Steam locomotive" content: the oil jets. The fire-tube boiler has internal tubes connecting the firebox to the smokebox through which the combustion gases flow transferring heat to the water. All the tubes together provide a large contact area, called the tube heating surface, between the gas and water in the boiler. Boiler water surrounds the firebox to stop the metal from becoming too hot. This is another area where the gas transfers heat to the water and is called the firebox heating surface. Ash and char collect in the smokebox as the gas gets drawn up the chimney ("stack" or "smokestack" in the


title: "Steam locomotive" content: US) by the exhaust steam from the cylinders. Surrounding the boiler are layers of insulation or lagging to reduce heat loss. The pressure in the boiler has to be monitored using a gauge mounted in the cab. Steam pressure can be released manually by the driver or fireman. If the pressure reaches the boiler's design working limit, a safety valve opens automatically to reduce the pressure and avoid a catastrophic accident. The exhaust steam from the engine cylinders shoots out of a nozzle pointing up the chimney in the smokebox. The steam entrains or drags the smokebox gases with it


title: "Steam locomotive" content: which maintains a lower pressure in the smokebox than that under the firebox grate. This pressure difference causes air to flow up through the coal bed and keeps the fire burning. The search for thermal efficiency greater than that of a typical fire-tube boiler led engineers, such as Nigel Gresley, to consider the water-tube boiler. Although he tested the concept on the LNER Class W1, the difficulties during development exceeded the will to increase efficiency by that route. The steam generated in the boiler not only moves the locomotive, but is also used to operate other devices such as the


title: "Steam locomotive" content: whistle, the air compressor for the brakes, the pump for replenishing the water in the boiler and the passenger car heating system. The constant demand for steam requires a periodic replacement of water in the boiler. The water is kept in a tank in the locomotive tender or wrapped around the boiler in the case of a tank locomotive. Periodic stops are required to refill the tanks; an alternative was a scoop installed under the tender that collected water as the train passed over a track pan located between the rails. While the locomotive is producing steam, the amount of


title: "Steam locomotive" content: water in the boiler is constantly monitored by looking at the water level in a transparent tube, or sight glass. Efficient and safe operation of the boiler requires keeping the level in between lines marked on the sight glass. If the water level is too high, steam production falls, efficiency is lost and water is carried out with the steam into the cylinders, possibly causing mechanical damage. More seriously, if the water level gets too low, the crown(top)sheet of the firebox becomes exposed. Without water on top of the sheet to transfer away the heat of combustion, it softens and


title: "Steam locomotive" content: fails, letting high-pressure steam into the firebox and the cab. The development of the fusible plug, a temperature-sensitive device, ensured a controlled venting of steam into the firebox to warn the fireman to add water. Scale builds up in the boiler and prevents adequate heat transfer, and corrosion eventually degrades the boiler materials to the point where it needs to be rebuilt or replaced. Start-up on a large engine may take hours of preliminary heating of the boiler water before sufficient steam is available. Although the boiler is typically placed horizontally, for locomotives designed to work in locations with steep


title: "Steam locomotive" content: slopes it may be more appropriate to consider a vertical boiler or one mounted such that the boiler remains horizontal but the wheels are inclined to suit the slope of the rails. The steam generated in the boiler fills the space above the water in the partially filled boiler. Its maximum working pressure is limited by spring-loaded safety valves. It is then collected either in a perforated tube fitted above the water level or by a dome that often houses the regulator valve, or throttle, the purpose of which is to control the amount of steam leaving the boiler. The


title: "Steam locomotive" content: steam then either travels directly along and down a steam pipe to the engine unit or may first pass into the wet header of a superheater, the role of the latter being to improve thermal efficiency and eliminate water droplets suspended in the "saturated steam", the state in which it leaves the boiler. On leaving the superheater, the steam exits the dry header of the superheater and passes down a steam pipe, entering the steam chests adjacent to the cylinders of a reciprocating engine. Inside each steam chest is a sliding valve that distributes the steam via ports that connect


title: "Steam locomotive" content: the steam chest to the ends of the cylinder space. The role of the valves is twofold: admission of each fresh dose of steam, and exhaust of the used steam once it has done its work. The cylinders are double-acting, with steam admitted to each side of the piston in turn. In a two-cylinder locomotive, one cylinder is located on each side of the vehicle. The cranks are set 90° out of phase. During a full rotation of the driving wheel, steam provides four power strokes; each cylinder receives two injections of steam per revolution. The first stroke is to


title: "Steam locomotive" content: the front of the piston and the second stroke to the rear of the piston; hence two working strokes. Consequently, two deliveries of steam onto each piston face in the two cylinders generates a full revolution of the driving wheel. Each piston is attached to the driving axle on each side by a connecting rod, and the driving wheels are connected together by coupling rods to transmit power from the main driver to the other wheels. Note that at the two "dead centres", when the connecting rod is on the same axis as the crankpin on the driving wheel, the


title: "Steam locomotive" content: connecting rod applies no torque to the wheel. Therefore, if both cranksets could be at "dead centre" at the same time, and the wheels should happen to stop in this position, the locomotive could not start moving. Therefore, the crankpins are attached to the wheels at a 90° angle to each other, so only one side can be at dead centre at a time. Each piston transmits power through a crosshead, connecting rod ("Main rod" in the US) and a crankpin on the driving wheel ("Main driver" in the US) or to a crank on a driving axle. The movement


title: "Steam locomotive" content: of the valves in the steam chest is controlled through a set of rods and linkages called the valve gear, actuated from the driving axle or from the crankpin; the valve gear includes devices that allow reversing the engine, adjusting valve travel and the timing of the admission and exhaust events. The cut-off point determines the moment when the valve blocks a steam port, "cutting off" admission steam and thus determining the proportion of the stroke during which steam is admitted into the cylinder; for example a 50% cut-off admits steam for half the stroke of the piston. The remainder


title: "Steam locomotive" content: of the stroke is driven by the expansive force of the steam. Careful use of cut-off provides economical use of steam and in turn reduces fuel and water consumption. The reversing lever ("Johnson bar" in the US), or screw-reverser (if so equipped), that controls the cut-off therefore performs a similar function to a gearshift in an automobile – maximum cut-off, providing maximum tractive effort at the expense of efficiency, is used to pull away from a standing start, whilst a cut-off as low as 10% is used when cruising, providing reduced tractive effort, and therefore lower fuel/water consumption. Exhaust steam


title: "Steam locomotive" content: is directed upwards out of the locomotive through the chimney, by way of a nozzle called a blastpipe, creating the familiar "chuffing" sound of the steam locomotive. The blastpipe is placed at a strategic point inside the smokebox that is at the same time traversed by the combustion gases drawn through the boiler and grate by the action of the steam blast. The combining of the two streams, steam and exhaust gases, is crucial to the efficiency of any steam locomotive, and the internal profiles of the chimney (or, strictly speaking, the "ejector") require careful design and adjustment. This has


title: "Steam locomotive" content: been the object of intensive studies by a number of engineers (and often ignored by others, sometimes with catastrophic consequences). The fact that the draught depends on the exhaust pressure means that power delivery and power generation are automatically self-adjusting. Among other things, a balance has to be struck between obtaining sufficient draught for combustion whilst giving the exhaust gases and particles sufficient time to be consumed. In the past, a strong draught could lift the fire off the grate, or cause the ejection of unburnt particles of fuel, dirt and pollution for which steam locomotives had an unenviable reputation.


title: "Steam locomotive" content: Moreover, the pumping action of the exhaust has the counter-effect of exerting "back pressure" on the side of the piston receiving steam, thus slightly reducing cylinder power. Designing the exhaust ejector became a specific science, with engineers such as Chapelon, Giesl and Porta making large improvements in thermal efficiency and a significant reduction in maintenance time and pollution. A similar system was used by some early gasoline/kerosene tractor manufacturers (Advance-Rumely/Hart-Parr) – the exhaust gas volume was vented through a cooling tower, allowing the steam exhaust to draw more air past the radiator. Running gear includes the brake gear, wheel sets,


title: "Steam locomotive" content: axleboxes, springing and the motion that includes connecting rods and valve gear. The transmission of the power from the pistons to the rails and the behaviour of the locomotive as a vehicle, being able to negotiate curves, points and irregularities in the track, is of paramount importance. Because reciprocating power has to be directly applied to the rail from 0 rpm upwards, this creates the problem of adhesion of the driving wheels to the smooth rail surface. Adhesive weight is the portion of the locomotive's weight bearing on the driving wheels. This is made more effective if a pair of


title: "Steam locomotive" content: driving wheels is able to make the most of its axle load, i.e. its individual share of the adhesive weight. Equalising beams connecting the ends of leaf springs have often been deemed a complication in Britain, however locomotives fitted with the beams have usually been less prone to loss of traction due to wheel-slip. Suspension using equalizing levers between driving axles, and between driving axles and trucks, was standard practice on North American locomotives to maintain even wheel loads when operating on uneven track. Locomotives with total adhesion, where all of the wheels are coupled together, generally lack stability at


title: "Steam locomotive" content: speed. To counter this, locomotives often fit unpowered carrying wheels mounted on two-wheeled trucks or four-wheeled bogies centred by springs/inverted rockers/geared rollers that help to guide the locomotive through curves. These usually take on weight – of the cylinders at the front or the firebox at the rear — when the width exceeds that of the mainframes. Locomotives with multiple coupled-wheels on a rigid chassis would have unacceptable flange forces on tight curves giving excessive flange and rail wear, track spreading and wheel climb derailments. One solution was to remove or thin the flanges on an axle. More common was


title: "Steam locomotive" content: to give axles end-play and use lateral motion control with spring or inclined-plane gravity devices. Railroads generally preferred locomotives with fewer axles, to reduce maintenance costs. The number of axles required was dictated by the maximum axle loading of the railroad in question. A builder would typically add axles until the maximum weight on any one axle was acceptable to the railroad's maximum axle loading. A locomotive with a wheel arrangement of two lead axles, two drive axles, and one trailing axle was a high-speed machine. Two lead axles were necessary to have good tracking at high speeds. Two drive


title: "Steam locomotive" content: axles had a lower reciprocating mass than three, four, five or six coupled axles. They were thus able to turn at very high speeds due to the lower reciprocating mass. A trailing axle was able to support a huge firebox, hence most locomotives with the wheel arrangement of 4-4-2 (American Type Atlantic) were called free steamers and were able to maintain steam pressure regardless of throttle setting. The chassis, or locomotive frame, is the principal structure onto which the boiler is mounted and which incorporates the various elements of the running gear. The boiler is rigidly mounted on a "saddle"


title: "Steam locomotive" content: beneath the smokebox and in front of the boiler barrel, but the firebox at the rear is allowed to slide forward and backwards, to allow for expansion when hot. European locomotives usually use "plate frames", where two vertical flat plates form the main chassis, with a variety of spacers and a buffer beam at each end to keep them apart. When inside cylinders are mounted between the frames, the plate frames are a single large casting that forms a major support. The axleboxes slide up and down to give some sprung suspension, against thickened webs attached to the frame, called


title: "Steam locomotive" content: "hornblocks". American practice for many years was to use built-up bar frames, with the smokebox saddle/cylinder structure and drag beam integrated therein. In the 1920s, with the introduction of "superpower", the cast-steel locomotive bed became the norm, incorporating frames, spring hangers, motion brackets, smokebox saddle and cylinder blocks into a single complex, sturdy but heavy casting. An S.N.C.F design study using welded tubular frames gave a rigid frame with a 30% weight reduction. Generally, the largest locomotives are permanently coupled to a tender that carries the water and fuel. Often, locomotives working shorter distances do not have a tender and


title: "Steam locomotive" content: carry the fuel in a bunker, with the water carried in tanks placed next to the boiler either in two tanks alongside (side tank and pannier tank), one on top (saddle tank) or one underneath (well tank); these are called tank engines and usually have a 'T' suffix added to the Whyte notation, e.g. 0-6-0T. The fuel used depended on what was economically available to the railway. In the UK and other parts of Europe, plentiful supplies of coal made this the obvious choice from the earliest days of the steam engine. Until 1870, the majority of locomotives in the


title: "Steam locomotive" content: United States burned wood, but as the Eastern forests were cleared, coal gradually became more widely used. Thereafter, coal became and remained the dominant fuel worldwide until the end of general use of steam locomotives. Railways serving sugar cane farming operations burned bagasse, a byproduct of sugar refining. In the US, the ready availability of oil made it a popular steam locomotive fuel after 1900 for the southwestern railroads, particularly the Southern Pacific. In the Australian state of Victoria after World War II, many steam locomotives were converted to heavy oil firing. German, Russian, Australian and British railways experimented with


title: "Steam locomotive" content: using coal dust to fire locomotives. During World War II, a number of Swiss steam shunting locomotives were modified to use electrically heated boilers, consuming around 480 kW of power collected from an overhead line with a pantograph. These locomotives were significantly less efficient than electric ones; they were used because Switzerland had access to plentiful hydroelectricity, and suffered from a shortage of coal because of the war. A number of tourist lines and heritage locomotives in Switzerland, Argentina and Australia have used light diesel-type oil. Water was supplied at stopping places and locomotive depots from a dedicated water tower


title: "Steam locomotive" content: connected to water cranes or gantries. In the UK, the US and France, water troughs ("track pans" in the US) were provided on some main lines to allow locomotives to replenish their water supply without stopping, from rainwater or snowmelt that filled the trough due to inclement weather. This was achieved by using a deployable "water scoop" fitted under the tender or the rear water tank in the case of a large tank engine; the fireman remotely lowered the scoop into the trough, the speed of the engine forced the water up into the tank, and the scoop was raised


title: "Steam locomotive" content: again once it was full. Water is an essential element in the operation of a steam locomotive. As Swengel argued: Swengel went on to note that "at low temperature and relatively low boiler outputs", good water and regular boiler washout was an acceptable practice, even though such maintenance was high. As steam pressures increased, however, a problem of "foaming" or "priming" developed in the boiler, wherein dissolved solids in the water formed "tough-skinned bubbles" inside the boiler, which in turn were carried into the steam pipes and could blow off the cylinder heads. To overcome the problem, hot mineral-concentrated water


title: "Steam locomotive" content: was deliberately wasted (blown down) from the boiler periodically. Higher steam pressures required more blowing-down of water out of the boiler. Oxygen generated by boiling water attacks the boiler, and with increased steam pressure the rate of rust (iron oxide) generated inside the boiler increases. One way to help overcome the problem was water treatment. Swengel suggested that these problems contributed to the interest in electrification of railways. In the 1970s, L.D. Porta developed a sophisticated system of heavy-duty chemical water treatment (Porta Treatment) that not only keeps the inside of the boiler clean and prevents corrosion, but modifies the


title: "Steam locomotive" content: foam in such a way as to form a compact "blanket" on the water surface that filters the steam as it is produced, keeping it pure and preventing carry-over into the cylinders of water and suspended abrasive matter. A steam locomotive is normally controlled from the boiler's backhead, and the crew is usually protected from the elements by a cab. A crew of at least two people is normally required to operate a steam locomotive. One, the train driver or engineer (North America), is responsible for controlling the locomotive's starting, stopping and speed, and the fireman is responsible for maintaining


title: "Steam locomotive" content: the fire, regulating steam pressure and monitoring boiler and tender water levels. Due to the historical loss of operational infrastructure and staffing, preserved steam locomotives operating on the mainline will often have a support crew travelling with the train. All locomotives are fitted with a variety of appliances. Some of these relate directly to the operation of the steam engine; while others are for signalling, train control or other purposes. In the United States, the Federal Railroad Administration mandated the use of certain appliances over the years in response to safety concerns. The most typical appliances are as follows: Water


title: "Steam locomotive" content: (feedwater) must be delivered to the boiler to replace that which is exhausted as steam after delivering a working stroke to the pistons. As the boiler is under pressure during operation, feedwater must be forced into the boiler at a pressure that is greater than the steam pressure, necessitating the use of some sort of pump. Hand-operated pumps sufficed for the very earliest locomotives. Later engines used pumps driven by the motion of the pistons (axle pumps), which were simple to operate, reliable and could handle large quantities of water but only operated when the locomotive was moving and could


title: "Steam locomotive" content: overload the valve gear and piston rods at high speeds. Steam injectors later replaced the pump, while some engines transitioned to turbopumps. Standard practice evolved to use two independent systems for feeding water to the boiler; either two steam injectors or, on more conservative designs, axle pumps when running at service speed and a steam injector for filling the boiler when stationary or at low speeds. By the 20th century virtually all new-built locomotives used only steam injectors – often one injector was supplied with "live" steam straight from the boiler itself and the other used exhaust steam from the


title: "Steam locomotive" content: locomotive's cylinders, which was more efficient (since it made use of otherwise wasted steam) but could only be used when the locomotive was in motion and the regulator was open. Injectors became unreliable if the feedwater was at a high temperature, so locomotives with feedwater heaters, tank locomotives with the tanks in contact with the boiler and condensing locomotives sometimes used reciprocating steam pumps or turbopumps. Vertical glass tubes, known as water gauges or water glasses, show the level of water in the boiler and are carefully monitored at all times while the boiler is being fired. Before the 1870s


title: "Steam locomotive" content: it was more common to have a series of try-cocks fitted to the boiler within reach of the crew; each try cock (at least two and usually three were fitted) was mounted at a different level. By opening each try-cock and seeing if steam or water vented through it, the level of water in the boiler could be estimated with limited accuracy. As boiler pressures increased the use of try-cocks became increasingly dangerous and the valves were prone to blockage with scale or sediment, giving false readings. This led to their replacement with the sight glass. As with the injectors,


title: "Steam locomotive" content: two glasses with separate fittings were usually installed to provide independent readings. The term for pipe and boiler insulation is "lagging" which derives from the cooper's term for a wooden barrel stave. Two of the earliest steam locomotives used wooden lagging to insulate their boilers: the Salamanca, the first commercially successful steam locomotive, built in 1812, and the Locomotion No. 1, the first steam locomotive to carry passengers on a public rail line. Large amounts of heat are wasted if a boiler is not insulated. Early locomotives used lags, shaped wooden staves, fitted lengthways along the boiler barrel, and held


title: "Steam locomotive" content: in place by hoops, metal bands, the terms and methods are from cooperage. Improved insulating methods included applying a thick paste containing a porous mineral such as kieselgur, or attaching shaped blocks of insulating compound such as magnesia blocks. In the latter days of steam, "mattresses" of stitched asbestos cloth stuffed with asbestos fibre were fixed to the boiler, on separators so as not quite to touch the boiler. However, asbestos is currently banned in most countries for health reasons. The most common modern day material is glass wool, or wrappings of aluminium foil. The lagging is protected by a


title: "Steam locomotive" content: close-fitted sheet-metal casing known as boiler clothing or cleading. Effective lagging is particularly important for fireless locomotives; however in recent times under the influence of L.D. Porta, "exaggerated" insulation has been practised for all types of locomotive on all surfaces liable to dissipate heat, such as cylinder ends and facings between the cylinders and the mainframes. This considerably reduces engine warmup time with marked increase in overall efficiency. Early locomotives were fitted with a valve controlled by a weight suspended from the end of a lever, with the steam outlet being stopped by a cone-shaped valve. As there was nothing


title: "Steam locomotive" content: to prevent the weighted lever from bouncing when the locomotive ran over irregularities in the track, thus wasting steam, the weight was later replaced by a more stable spring-loaded column, often supplied by Salter, a well-known spring scale manufacturer. The danger of these devices was that the driving crew could be tempted to add weight to the arm to increase pressure. Most early boilers were fitted with a tamper-proof "lockup" direct-loaded ball valve protected by a cowl. In the late 1850s, John Ramsbottom introduced a safety valve that became popular in Britain during the latter part of the 19th century.


title: "Steam locomotive" content: Not only was this valve tamper-proof, but tampering by the driver could only have the effect of easing pressure. George Richardson's safety valve was an American invention introduced in 1875, and was designed to release the steam only at the moment when the pressure attained the maximum permitted. This type of valve is in almost universal use at present. Britain's Great Western Railway was a notable exception to this rule, retaining the direct-loaded type until the end of its separate existence, because it was considered that such a valve lost less pressure between opening and closing. The earliest locomotives did


title: "Steam locomotive" content: not show the pressure of steam in the boiler, but it was possible to estimate this by the position of the safety valve arm which often extended onto the firebox back plate; gradations marked on the spring column gave a rough indication of the actual pressure. The promoters of the Rainhill trials urged that each contender have a proper mechanism for reading the boiler pressure, and Stephenson devised a nine-foot vertical tube of mercury with a sight-glass at the top, mounted alongside the chimney, for his "Rocket". The Bourdon tube gauge, in which the pressure straightens an oval-section coiled tube


title: "Steam locomotive" content: of brass or bronze connected to a pointer, was introduced in 1849 and quickly gained acceptance, and is still used today. Some locomotives have an additional pressure gauge in the steam chest. This helps the driver avoid wheel-slip at startup, by warning if the regulator opening is too great. Wood-burners emit large quantities of flying sparks which necessitate an efficient spark-arresting device generally housed in the smokestack. Many different types were fitted, the most common early type being the Bonnet stack that incorporated a cone-shaped deflector placed before the mouth of the chimney pipe, and a wire screen covering the


title: "Steam locomotive" content: wide stack exit. A more-efficient design was the Radley and Hunter centrifugal stack patented in 1850 (commonly known as the diamond stack), incorporating baffles so oriented as to induce a swirl effect in the chamber that encouraged the embers to burn out and fall to the bottom as ash. In the self-cleaning smokebox the opposite effect was achieved: by allowing the flue gasses to strike a series of deflector plates, angled in such a way that the blast was not impaired, the larger particles were broken into small pieces that would be ejected with the blast, rather than settle in


title: "Steam locomotive" content: the bottom of the smokebox to be removed by hand at the end of the run. As with the arrestor, a screen was incorporated to retain any large embers. Locomotives of the British Railways standard classes fitted with self-cleaning smokeboxes were identified by a small cast oval plate marked "S.C.", fitted at the bottom of the smokebox door. These engines required different disposal procedures and the plate highlighted this need to depot staff. A factor that limits locomotive performance is the rate at which fuel is fed into the fire. In the early 20th century some locomotives became so large


title: "Steam locomotive" content: that the fireman could not shovel coal fast enough. In the United States, various steam-powered mechanical stokers became standard equipment and were adopted and used elsewhere including Australia and South Africa. Introducing cold water into a boiler reduces power, and from the 1920s a variety of heaters were incorporated. The most common type for locomotives was the exhaust steam feedwater heater that piped some of the exhaust through small tanks mounted on top of the boiler or smokebox or into the tender tank; the warm water then had to be delivered to the boiler by a small auxiliary steam pump.


title: "Steam locomotive" content: The rare economiser type differed in that it extracted residual heat from the exhaust gases. An example of this is the pre-heater drum(s) found on the Franco-Crosti boiler. The use of live steam and exhaust steam injectors also assists in the pre-heating of boiler feedwater to a small degree, though there is no efficiency advantage to live steam injectors. Such pre-heating also reduces the thermal shock that a boiler might experience when cold water is introduced directly. This is further helped by the top feed, where water is introduced to the highest part of the boiler and made to trickle


title: "Steam locomotive" content: over a series of trays. G.J. Churchward fitted this arrangement to the high end of his domeless coned boilers. Other British lines such as the LBSCR fitted some locomotives with the top feed inside a separate dome forward of the main one. Steam locomotives consume vast quantities of water because they operate on an open cycle, expelling their steam immediately after a single use rather than recycling it in a closed loop as stationary and marine steam engines do. Water was a constant logistical problem, and condensing engines were devised for use in desert areas. These engines had huge radiators


title: "Steam locomotive" content: in their tenders and instead of exhausting steam out of the funnel it was captured, passed back to the tender and condensed. The cylinder lubricating oil was removed from the exhausted steam to avoid a phenomenon known as priming, a condition caused by foaming in the boiler which would allow water to be carried into the cylinders causing damage because of its incompressibility. The most notable engines employing condensers (Class 25, the "puffers which never puff") worked across the Karoo desert of South Africa from the 1950s until the 1980s. Some British and American locomotives were equipped with scoops which


title: "Steam locomotive" content: collected water from "water troughs" ("track pans" in the US) while in motion, thus avoiding stops for water. In the US, small communities often did not have refilling facilities. During the early days of railroading, the crew simply stopped next to a stream and filled the tender using leather buckets. This was known as "jerking water" and led to the term "jerkwater towns" (meaning a small town, a term which today is considered derisive). In Australia and South Africa, locomotives in drier regions operated with large oversized tenders and some even had an additional water wagon, sometimes called a "canteen"


title: "Steam locomotive" content: or in Australia (particularly in New South Wales) a "water gin". Steam locomotives working on underground railways (such as London's Metropolitan Railway) were fitted with condensing apparatus to prevent steam from escaping into the railway tunnels. These were still being used between King's Cross and Moorgate into the early 1960s. Locomotives have their own braking system, independent from the rest of the train. Locomotive brakes employ large shoes which press against the driving wheel treads. With the advent of compressed air brakes, a separate system allowed the driver to control the brakes on all cars. A single-stage, steam-driven, air compressor


title: "Steam locomotive" content: was mounted on the side of the boiler. Long freight trains needed more air and a two-stage compressor with LP and HP cylinders, driven by cross-compound HP and LP steam cylinders, was introduced. It had three and a half times the capacity of the single stage. Most were made by Westinghouse. Two were fitted in front of the smokebox on big articulated locomotives. Westinghouse systems were used in the United States, Canada, Australia and New Zealand. An alternative to the air brake is the vacuum brake, in which a steam-operated ejector is mounted on the engine instead of the air


title: "Steam locomotive" content: pump, to create a vacuum and release the brakes. A secondary ejector or crosshead vacuum pump is used to maintain the vacuum in the system against the small leaks in the pipe connections between carriages and wagons. Vacuum systems existed on British, Indian, West Australian and South African railway networks. Steam locomotives are fitted with sandboxes from which sand can be deposited on top of the rail to improve traction and braking in wet or icy weather. On American locomotives the sandboxes, or sand domes, are usually mounted on top of the boiler. In Britain, the limited loading gauge precludes


title: "Steam locomotive" content: this, so the sandboxes are mounted just above, or just below, the running plate. The pistons and valves on the earliest locomotives were lubricated by the enginemen dropping a lump of tallow down the blast pipe. As speeds and distances increased, mechanisms were developed that injected thick mineral oil into the steam supply. The first, a displacement lubricator, mounted in the cab, uses a controlled stream of steam condensing into a sealed container of oil. Water from the condensed steam displaces the oil into pipes. The apparatus is usually fitted with sight-glasses to confirm the rate of supply. A later


title: "Steam locomotive" content: method uses a mechanical pump worked from one of the crossheads. In both cases, the supply of oil is proportional to the speed of the locomotive. Lubricating the frame components (axle bearings, horn blocks and bogie pivots) depends on capillary action: trimmings of worsted yarn are trailed from oil reservoirs into pipes leading to the respective component. The rate of oil supplied is controlled by the size of the bundle of yarn and not the speed of the locomotive, so it is necessary to remove the trimmings (which are mounted on wire) when stationary. However, at regular stops (such as


title: "Steam locomotive" content: a terminating station platform), oil finding its way onto the track can still be a problem. Crank pin and crosshead bearings carry small cup-shaped reservoirs for oil. These have feed pipes to the bearing surface that start above the normal fill level, or are kept closed by a loose-fitting pin, so that only when the locomotive is in motion does oil enter. In United Kingdom practice the cups are closed with simple corks, but these have a piece of porous cane pushed through them to admit air. It is customary for a small capsule of pungent oil (aniseed or garlic)


title: "Steam locomotive" content: to be incorporated in the bearing metal to warn if the lubrication fails and excess heating or wear occurs. When the locomotive is running under power, a draught on the fire is created by the exhaust steam directed up the chimney by the blastpipe. Without draught, the fire will quickly die down and steam pressure will fall. When the locomotive is stopped, or coasting with the regulator closed, there is no exhaust steam to create a draught, so the draught is maintained by means of a blower. This is a ring placed either around the base of the chimney, or


title: "Steam locomotive" content: around the blast pipe orifice, containing several small steam nozzles directed up the chimney. These nozzles are fed with steam directly from the boiler, controlled by the blower valve. When the regulator is open, the blower valve is closed; when the driver intends to close the regulator, he will first open the blower valve. It is important that the blower be opened before the regulator is closed, since without draught on the fire, there may be backdraught – where atmospheric air blows down the chimney, causing the flow of hot gases through the boiler tubes to be reversed, with the


title: "Steam locomotive" content: fire itself being blown through the firehole onto the footplate, with serious consequences for the crew. The risk of backdraught is higher when the locomotive enters a tunnel because of the pressure shock. The blower is also used to create draught when steam is being raised at the start of the locomotive's duty, at any time when the driver needs to increase the draught on the fire, and to clear smoke from the driver's line of vision. Blowbacks were fairly common. In a 1955 report on an accident near Dunstable, the Inspector wrote, "In 1953 twenty-three cases, which were not


title: "Steam locomotive" content: caused by an engine defect, were reported and they resulted in 26 enginemen receiving injuries. In 1954 the number of occurrences and of injuries were the same and there was also one fatal casualty." They remain a problem, as evidenced by the 2012 incident with BR standard class 7 70013 Oliver Cromwell. In British and European (except former Soviet Union countries) practice, locomotives usually have buffers at each end to absorb compressive loads ("buffets"). The tensional load of drawing the train (draft force) is carried by the coupling system. Together these control slack between the locomotive and train, absorb minor


title: "Steam locomotive" content: impacts and provide a bearing point for pushing movements. In Canadian and American practice all of the forces between the locomotive and cars are handled through the coupler – particularly the Janney coupler, long standard on American railroad rolling stock – and its associated draft gear, which allows some limited slack movement. Small dimples called "poling pockets" at the front and rear corners of the locomotive allowed cars to be pushed onto an adjacent track using a pole braced between the locomotive and the cars. In Britain and Europe, North American style "buckeye" and other couplers that handle forces between


title: "Steam locomotive" content: items of rolling stock have become increasingly popular. A pilot was usually fixed to the front end of locomotives, although in European and a few other railway systems including New South Wales, they were considered unnecessary. Plough-shaped, sometimes called "cow catchers", they were quite large and were designed to remove obstacles from the track such as cattle, bison, other animals or tree limbs. Though unable to "catch" stray cattle, these distinctive items remained on locomotives until the end of steam. Switching engines usually replaced the pilot with small steps, known as "footboards". Many systems used the pilot and other design


title: "Steam locomotive" content: features to produce a distinctive appearance. When night operations began, railway companies in some countries equipped their locomotives with lights to allow the driver to see what lay ahead of the train, or to enable others to see the locomotive. Headlights were originally oil or acetylene lamps, but when electric arc lamps became available in the late 1880s, they quickly replaced the older types. Britain did not adopt bright headlights as they would affect night vision and so could mask the low-intensity oil lamps used in the semaphore signals and at each end of trains, increasing the danger of missing


title: "Steam locomotive" content: signals, especially on busy tracks. Locomotive stopping distances were also normally much greater than the range of headlights, and the railways were well-signalled and fully fenced to prevent livestock and people from straying onto them, largely negating the need for bright lamps. Thus low-intensity oil lamps continued to be used, positioned on the front of locomotives to indicate the class of each train. Four "lamp irons" (brackets on which to place the lamps) were provided: one below the chimney and three evenly spaced across the top of the buffer beam. The exception to this was the Southern Railway and its


title: "Steam locomotive" content: constituents, who added an extra lamp iron each side of the smokebox, and the arrangement of lamps (or in daylight, white circular plates) told railway staff the origin and destination of the train. On all vehicles, equivalent lamp irons were also provided on the rear of the locomotive or tender for when the locomotive was running tender- or bunker-first. In some countries, heritage steam operation continues on the national network. Some railway authorities have mandated powerful headlights on at all times, including during daylight. This was to further inform the public or track workers of any active trains. Locomotives used


title: "Steam locomotive" content: bells and steam whistles from earliest days of steam locomotion. In the United States, India and Canada, bells warned of a train in motion. In Britain, where all lines are by law fenced throughout, bells were only a requirement on railways running on a road (i.e. not fenced off), for example a tramway along the side of the road or in a dockyard. Consequently, only a minority of locomotives in the UK carried bells. Whistles are used to signal personnel and give warnings. Depending on the terrain the locomotive was being used in, the whistle could be designed for long-distance


title: "Steam locomotive" content: warning of impending arrival, or for more localised use. Early bells and whistles were sounded through pull-string cords and levers. Automatic bell ringers came into widespread use in the US after 1910. From the early 20th century operating companies in such countries as Germany and Britain began to fit locomotives with Automatic Warning System (AWS) in-cab signalling, which automatically applied the brakes when a signal was passed at "caution". In Britain, these became mandatory in 1956. In the United States, the Pennsylvania Railroad also fitted their locomotives with such devices. The booster engine was an auxiliary steam engine which provided


title: "Steam locomotive" content: extra tractive effort for starting. It was a low speed device, usually mounted on the trailing truck. It was dis-engaged via an idler gear at a low speed, eg 30 km/hr. Boosters were widely used in the US and tried experimentally in Britain and France. On the narrow-gauged New Zealand railway system, six Kb 4-8-4 locomotives were fitted with boosters, the only engines in the world to have such equipment. Booster engines were also fitted to tender trucks in the US and known as auxiliary locomotives. Two and even three truck axles were connected together using side rods which limited


title: "Steam locomotive" content: them to slow-speed service. The firedoor is used to cover the firehole when coal is not being added. It serves two purposes, first it prevents air being drawn over the top of the fire, rather forcing it to be drawn through it. The second purpose is to safeguard the train crew against blowbacks. It does however have a means to allow some air to pass over the top of the fire (referred to as "secondary air") to complete the combustion of gases produced by the fire. Firedoors come in multiple designs, the most basic of which is a single piece


title: "Steam locomotive" content: which is hinged on one side and can swing open onto the footplate. This design has two issues, first it takes up lots of room on the footplate the second is the draught will tend to pull it completely shut, thus cutting off any secondary air. To compensate for this some locomotives are fitted with a latch that prevents the firedoor from closing completely whereas others have a small vent on the door that may be opened to allow secondary air to flow through. Though it was considered to design a firedoor that opens inwards into the firebox thus preventing


title: "Steam locomotive" content: the inconvience caused on the footplate, such a door would be exposed to the full heat of the fire and would likely deform, thus becoming useless. A more popular type of firedoor consists of a two piece sliding door operated by a single lever. There are tracks above and below the firedoor which the door runs along. These tracks are prone to becoming jammed by debris and the doors required more effort to open than the aforementioned swinging door. In order to address this some firedoors use powered operation which utilized a steam or air cylinder to open the door.


title: "Steam locomotive" content: Among these are the butterfly doors which pivot at the upper corner, the pivoting action offers low resistance to the cylinder that opens the door. Numerous variations on the basic locomotive occurred as railways attempted to improve efficiency and performance. Early steam locomotives had two cylinders, one either side, and this practice persisted as the simplest arrangement. The cylinders could be mounted between the main frames (known as "inside" cylinders), or mounted outside the frames and driving wheels ("outside" cylinders). Inside cylinders are driven by cranks built into the driving axle; outside cylinders are driven by cranks on extensions to


title: "Steam locomotive" content: the driving axles. Later designs employed three or four cylinders, mounted both inside and outside the frames, for a more even power cycle and greater power output. This was at the expense of more complicated valve gear and increased maintenance requirements. In some cases the third cylinder was added inside simply to allow for smaller diameter outside cylinders, and hence reduce the width of the locomotive for use on lines with a restricted loading gauge, for example the SR K1 and U1 classes. Most British express-passenger locomotives built between 1930 and 1950 were 4-6-0 or 4-6-2 types with three or


title: "Steam locomotive" content: four cylinders (e.g. GWR 6000 Class, LMS Coronation Class, SR Merchant Navy Class, LNER Gresley Class A3). From 1951, all but one of the 999 new British Rail standard class steam locomotives across all types used 2-cylinder configurations for easier maintenance. Early locomotives used a simple valve gear that gave full power in either forward or reverse. Soon the Stephenson valve gear allowed the driver to control cut-off; this was largely superseded by Walschaerts valve gear and similar patterns. Early locomotive designs using slide valves and outside admission were relatively easy to construct, but inefficient and prone to wear. Eventually,


title: "Steam locomotive" content: slide valves were superseded by inside admission piston valves, though there were attempts to apply poppet valves (commonly used in stationary engines) in the 20th century. Stephenson valve gear was generally placed within the frame and was difficult to access for maintenance; later patterns applied outside the frame were more readily visible and maintained. Compound locomotives were used from 1876, expanding the steam twice or more through separate cylinders – reducing thermal losses caused by cylinder cooling. Compound locomotives were especially useful in trains where long periods of continuous efforts were needed. Compounding contributed to the dramatic increase in power


title: "Steam locomotive" content: achieved by André Chapelon's rebuilds from 1929. A common application was in articulated locomotives, the most common being that designed by Anatole Mallet, in which the high-pressure stage was attached directly to the boiler frame; in front of this was pivoted a low-pressure engine on its own frame, which takes the exhaust from the rear engine. More-powerful locomotives tend to be longer, but long rigid-framed designs are impractical for the tight curves frequently found on narrow-gauge railways. Various designs for articulated locomotives were developed to overcome this problem. The Mallet and the Garratt were the two most popular, both using


title: "Steam locomotive" content: a single boiler and two engines (sets of cylinders and driving wheels). The Garratt has two power bogies, whereas the Mallet has one. There were also a few examples of triplex locomotives that had a third engine under the tender. Both the front and tender engines were low-pressure compounded, though they could be operated simple (high-pressure) for starting off. Other less common variations included the Fairlie locomotive, which had two boilers back-to-back on a common frame, with two separate power bogies. Duplex locomotives, containing two engines in one rigid frame, were also tried, but were not notably successful. For example,


title: "Steam locomotive" content: the 4-4-4-4 Pennsylvania Railroad's T1 class, designed for very fast running, suffered recurring and ultimately unfixable slippage problems throughout their careers. For locomotives where a high starting torque and low speed were required, the conventional direct drive approach was inadequate. "Geared" steam locomotives, such as the Shay, the Climax and the Heisler, were developed to meet this need on industrial, logging, mine and quarry railways. The common feature of these three types was the provision of reduction gearing and a drive shaft between the crankshaft and the driving axles. This arrangement allowed the engine to run at a much higher


title: "Steam locomotive" content: speed than the driving wheels compared to the conventional design, where the ratio is 1:1. In the United States on the Southern Pacific Railroad, a series of cab forward locomotives were produced with the cab and the firebox at the front of the locomotive and the tender behind the smokebox, so that the engine appeared to run backwards. This was only possible by using oil-firing. Southern Pacific selected this design to provide air free of smoke for the engine driver to breathe as the locomotive passed through mountain tunnels and snow sheds. Another variation was the Camelback locomotive, with the


title: "Steam locomotive" content: cab situated halfway along the boiler. In England, Oliver Bulleid developed the SR Leader class locomotive during the nationalisation process in the late 1940s. The locomotive was heavily tested but several design faults (such as coal firing and sleeve valves) meant that this locomotive and the other part-built locomotives were scrapped. The cab-forward design was taken by Bulleid to Ireland, where he moved after nationalisation, where he developed the "turfburner". This locomotive was more successful, but was scrapped due to the dieselisation of the Irish railways. The only preserved cab forward locomotive is Southern Pacific 4294 in Sacramento, California. In


title: "Steam locomotive" content: France, the three Heilmann locomotives were built with a cab forward design. Steam turbines were created as an attempt to improve the operation and efficiency of steam locomotives. Experiments with steam turbines using direct-drive and electrical transmissions in various countries proved mostly unsuccessful. The London, Midland and Scottish Railway built the Turbomotive, a largely successful attempt to prove the efficiency of steam turbines. Had it not been for the outbreak of World War II, more may have been built. The Turbomotive ran from 1935 to 1949, when it was rebuilt into a conventional locomotive because many parts required replacement, an