Butte is the county seat of Silver Bow County, United States. In 1977, the city and county governments consolidated to form the sole entity of Butte-Silver Bow; the city covers 718 square miles, according to the 2010 census, has a population of 33,503, making it Montana's fifth largest city. It is served by Bert Mooney Airport with airport code BTM. Established in 1864 as a mining camp in the northern Rocky Mountains on the Continental Divide, Butte experienced rapid development in the late-nineteenth century, was Montana's first major industrial city. In its heyday between the late-nineteenth and early-twentieth centuries, it was one of the largest copper boomtowns in the American West. Employment opportunities in the mines attracted surges of Asian and European immigrants the Irish. Butte was the site of various historical events involving its mining industry and active labor unions and Socialist politics, the most famous of, the labor riot of 1914. Despite the dominance of the Anaconda Copper Mining Company, Butte was never a company town.
Other major events in the city's history include the 1917 Speculator Mine disaster, the largest hard rock mining disaster in world history. Over the course of its history, Butte's mining and smelting operations generated an excess of $48 billion worth of ore, but resulted in numerous environmental implications for the city: The upper Clark Fork River, with headwaters at Butte, is the largest Superfund site in the United States, the city is home to the Berkeley Pit. In the late-twentieth century, cleanup efforts from the EPA were instated, the Butte Citizens Technical Environmental Committee was established in 1984. In the 21st century, efforts at interpreting and preserving Butte's heritage are addressing both the town's historical significance and the continuing importance of mining to its economy and culture; the city's Uptown Historic District, on the National Register of Historic Places, is one of the largest National Historic Landmark Districts in the United States, containing nearly 6,000 contributing properties.
The city is home to Montana Tech, a public engineering and technical university. Prior to Butte's formal establishment in 1864, the area consisted of a mining camp that had developed in the early 1860s; the city is located in the Silver Bow Creek Valley, a natural bowl sitting high in the Rockies straddling the Continental Divide, positioned on the southwestern side of a large mass of granite known as the Boulder Batholith, which dates to the Cretaceous era. In 1864, William L. Farlin founded the Asteroid Mine; the mines attracted workers from Cornwall Ireland & Wales, Canada, Austria, China, Montenegro and more. In the ethnic neighborhoods, young men formed gangs to protect their territory and socialize into adult life, including the Irish of Dublin Gulch, the Eastern Europeans of the McQueen Addition, the Italians of Meaderville. Among the migrants, many Chinese workers moved in, amongst them set up businesses that led to the creation of a Chinatown in Butte; the Chinese migrations stopped in 1882 with the passage of the Chinese Exclusion Act.
There was anti-Chinese sentiment in the 1870s and onwards due to racism on the part of the white settlers, exacerbated by economic depression, in 1895, the chamber of commerce and labor unions started a boycott of Chinese owned businesses. The business owners fought back by winning; the history of the Chinese migrants in Butte is documented in the Mai Wah Museum. The influx of miners gave Butte a reputation as a wide-open town; the city's saloon and red-light district, called the "Line" or "The Copper Block", was centered on Mercury Street, where the elegant bordellos included the famous Dumas Brothel. Behind the brothel was the famous Venus Alley, where women plied their trade in small cubicles called "cribs." The red-light district brought miners and other men from all over the region and remained open until 1982 after the closure of the Dumas Brothel. Commercial breweries first opened in Butte in the 1870s, were a large staple of the city's early economy; the breweries were always staffed by union workers.
Most ethnic groups in Butte, from Germans and Irish to Italians and various Eastern Europeans, including children, enjoyed the locally brewed lagers and other types of beer. In the late nineteenth century, copper was in great demand because of new technologies such as electric power that required the use of copper. Four industrial magnates fought for control of Butte's mining wealth; these four "Copper Kings" were William A. Clark, Marcus Daly, F. Augustus Heinze, James A. Murray; the Anaconda Copper Mining Company began in 1881 when Marcus Daly bought a small mine named the Anaconda. He was a part-owner, mine manager and engineer of the Alice, a silver mine in Walkerville, a suburb of Butte. While working in the Alice, he noticed significant quantities of high grade copper ore. Daly obtained permission to inspect nearby workings. After Daly's employers, the Walker Brothers, refused to buy the Anaconda, Daly sold his interest in the Alice and bought it himself. Daly asked San Francisco mining magnate, for additional support.
Hearst agreed to buy one-fourth of the new company's stock without visiting the site. While mining
Yellowstone National Park
Yellowstone National Park is an American national park located in Wyoming and Idaho. It was established by the U. S. Congress and signed into law by President Ulysses S. Grant on March 1, 1872. Yellowstone was the first national park in the U. S. and is widely held to be the first national park in the world. The park is known for its wildlife and its many geothermal features Old Faithful geyser, one of its most popular features, it has many types of ecosystems. It is part of the South Central Rockies forests ecoregion. Native Americans have lived in the Yellowstone region for at least 11,000 years. Aside from visits by mountain men during the early-to-mid-19th century, organized exploration did not begin until the late 1860s. Management and control of the park fell under the jurisdiction of the Secretary of the Interior, the first being Columbus Delano. However, the U. S. Army was subsequently commissioned to oversee management of Yellowstone for a 30-year period between 1886 and 1916. In 1917, administration of the park was transferred to the National Park Service, created the previous year.
Hundreds of structures have been built and are protected for their architectural and historical significance, researchers have examined more than a thousand archaeological sites. Yellowstone National Park spans an area of 3,468.4 square miles, comprising lakes, canyons and mountain ranges. Yellowstone Lake is one of the largest high-elevation lakes in North America and is centered over the Yellowstone Caldera, the largest supervolcano on the continent; the caldera is considered an active volcano. It has erupted with tremendous force several times in the last two million years. Half of the world's geysers and hydrothermal features are in Yellowstone, fueled by this ongoing volcanism. Lava flows and rocks from volcanic eruptions cover most of the land area of Yellowstone; the park is the centerpiece of the Greater Yellowstone Ecosystem, the largest remaining nearly-intact ecosystem in the Earth's northern temperate zone. In 1978, Yellowstone was named a UNESCO World Heritage Site. Hundreds of species of mammals, birds and reptiles have been documented, including several that are either endangered or threatened.
The vast forests and grasslands include unique species of plants. Yellowstone Park is the largest and most famous megafauna location in the contiguous United States. Grizzly bears and free-ranging herds of bison and elk live in this park; the Yellowstone Park bison herd is the largest public bison herd in the United States. Forest fires occur in the park each year. Yellowstone has numerous recreational opportunities, including hiking, boating and sightseeing. Paved roads provide close access to the major geothermal areas as well as some of the lakes and waterfalls. During the winter, visitors access the park by way of guided tours that use either snow coaches or snowmobiles; the park contains the headwaters of the Yellowstone River. Near the end of the 18th century, French trappers named the river Roche Jaune, a translation of the Hidatsa name Mi tsi a-da-zi. American trappers rendered the French name in English as "Yellow Stone". Although it is believed that the river was named for the yellow rocks seen in the Grand Canyon of the Yellowstone, the Native American name source is unclear.
The human history of the park begins at least 11,000 years ago when Native Americans began to hunt and fish in the region. During the construction of the post office in Gardiner, Montana, in the 1950s, an obsidian projectile point of Clovis origin was found that dated from 11,000 years ago; these Paleo-Indians, of the Clovis culture, used the significant amounts of obsidian found in the park to make cutting tools and weapons. Arrowheads made of Yellowstone obsidian have been found as far away as the Mississippi Valley, indicating that a regular obsidian trade existed between local tribes and tribes farther east. By the time white explorers first entered the region during the Lewis and Clark Expedition in 1805, they encountered the Nez Perce and Shoshone tribes. While passing through present day Montana, the expedition members heard of the Yellowstone region to the south, but they did not investigate it. In 1806, John Colter, a member of the Lewis and Clark Expedition, left to join a group of fur trappers.
After splitting up with the other trappers in 1807, Colter passed through a portion of what became the park, during the winter of 1807–1808. He observed at least one geothermal area near Tower Fall. After surviving wounds he suffered in a battle with members of the Crow and Blackfoot tribes in 1809, Colter described a place of "fire and brimstone" that most people dismissed as delirium. Over the next 40 years, numerous reports from mountain men and trappers told of boiling mud, steaming rivers, petrified trees, yet most of these reports were believed at the time to be myth. After an 1856 exploration, mountain man Jim Bridger reported observing boiling springs, spouting water, a mountain of glass and yellow rock; these reports were ignored because Bridger was a known "spinner of yarns". In 1859, a U. S. Army Surveyor named Captain William F. Raynolds embarked on a two-year survey of the northern Rockies. After wintering in Wyoming, in May 1860, Raynolds and his party – which included naturalist Ferdinand Vandeveer Hayden and guide Jim B
Montana is a landlocked state in the Northwestern United States. Montana has several nicknames, although none are official, including "Big Sky Country" and "The Treasure State", slogans that include "Land of the Shining Mountains" and more "The Last Best Place". Montana is the 4th largest in area, the 8th least populous, the 3rd least densely populated of the 50 U. S. states. The western half of Montana contains numerous mountain ranges. Smaller island ranges are found throughout the state. In all, 77 named; the eastern half of Montana is characterized by badlands. Montana is bordered by Idaho to the west, Wyoming to the south, North Dakota and South Dakota to the east, the Canadian provinces of British Columbia and Saskatchewan to the north; the economy is based on agriculture, including ranching and cereal grain farming. Other significant economic resources include oil, coal, hard rock mining, lumber; the health care and government sectors are significant to the state's economy. The state's fastest-growing sector is tourism.
Nearly 13 million tourists annually visit Glacier National Park, Yellowstone National Park, the Beartooth Highway, Flathead Lake, Big Sky Resort, other attractions. The name Montana comes from the Spanish word Montaña, which in turn comes from the Latin word Montanea, meaning "mountain", or more broadly, "mountainous country". Montaña del Norte was the name given by early Spanish explorers to the entire mountainous region of the west; the name Montana was added to a bill by the United States House Committee on Territories, chaired at the time by Rep. James Ashley of Ohio, for the territory that would become Idaho Territory; the name was changed by Representatives Henry Wilson and Benjamin F. Harding, who complained Montana had "no meaning"; when Ashley presented a bill to establish a temporary government in 1864 for a new territory to be carved out of Idaho, he again chose Montana Territory. This time Rep. Samuel Cox of Ohio, objected to the name. Cox complained the name was a misnomer given most of the territory was not mountainous and that a Native American name would be more appropriate than a Spanish one.
Other names such as Shoshone were suggested, but it was decided the Committee on Territories could name it whatever they wanted, so the original name of Montana was adopted. Montana is one of the nine Mountain States, located in the north of the region known as the Western United States, it borders North South Dakota to the east. Wyoming is to the south, Idaho is to the west and southwest, three Canadian provinces, British Columbia and Saskatchewan, are to the north. With an area of 147,040 square miles, Montana is larger than Japan, it is the fourth largest state in the United States after Alaska and California. S. state. The state's topography is defined by the Continental Divide, which splits much of the state into distinct eastern and western regions. Most of Montana's 100 or more named mountain ranges are in the state's western half, most of, geologically and geographically part of the Northern Rocky Mountains; the Absaroka and Beartooth ranges in the state's south-central part are technically part of the Central Rocky Mountains.
The Rocky Mountain Front is a significant feature in the state's north-central portion, isolated island ranges that interrupt the prairie landscape common in the central and eastern parts of the state. About 60 percent of the state is part of the northern Great Plains; the Bitterroot Mountains—one of the longest continuous ranges in the Rocky Mountain chain from Alaska to Mexico—along with smaller ranges, including the Coeur d'Alene Mountains and the Cabinet Mountains, divide the state from Idaho. The southern third of the Bitterroot range blends into the Continental Divide. Other major mountain ranges west of the Divide include the Cabinet Mountains, the Anaconda Range, the Missions, the Garnet Range, Sapphire Mountains, Flint Creek Range; the Divide's northern section, where the mountains give way to prairie, is part of the Rocky Mountain Front. The front is most pronounced in the Lewis Range, located in Glacier National Park. Due to the configuration of mountain ranges in Glacier National Park, the Northern Divide crosses this region and turns east in Montana at Triple Divide Peak.
It causes the Waterton River and Saint Mary rivers to flow north into Alberta, Canada. There they join the Saskatchewan River, which empties into Hudson Bay. East of the divide, several parallel ranges cover the state's southern part, including the Gravelly Range, the Madison Range, Gallatin Range, Absaroka Mountains and the Beartooth Mountains; the Beartooth Plateau is the largest continuous land mass over 10,000 feet high in the continental United States. It contains Granite Peak, 12,799 feet high. North of these ranges are the Big Belt Mountains, Bridger Mountains, Tobacco Roots, several island ranges, including the Crazy Mountains and Little Belt Mountains. Between many mountain ranges are rich river valleys; the Big Hole Valley, Bitterroot Valley, Gallatin Valley, Flathead Valley, Paradise Valley have extensive agricultural resources and multiple opportunities for tourism and recreation. East and north of this transition zone are the expansive and sparsely populated Northern Plains, with tableland prairies, smaller island mountain ranges, badlands.
The isolated island ranges east of the Divide include the Bear Paw Mountains, Bull Mountains, Castle Mountains, Crazy Mountains, Highwood Mountains, Judi
Grant-Kohrs Ranch National Historic Site
The Grant-Kohrs Ranch National Historic Site, created in 1972, commemorates the Western cattle industry from its 1850s inception through recent times. The original ranch was established in 1862 by a Canadian fur trader, Johnny Grant, at Cottonwood Creek, along the banks of the Clark Fork river; the ranch was expanded by a cattle baron, Conrad Kohrs. The 1,618 acres historic site is maintained today as a working ranch by the National Park Service. Johnny Francis Grant was born at Fort Edmonton, Canada, his mother died when he was only three years old, so he was sent to Trois-Rivières, Quebec, to be raised by his grandmother. His father, Captain Richard Grant, was a Hudson's Bay Company employee, therefore, in his mid-teens, he left for Fort Hall, Idaho, to meet up with his father. There he learned the trading business. However, in the 1840s the fur trade was dying out, so Johnny Grant and his brother James turned to trading with emigrants traveling west along the Oregon Trail, he made a considerable profit by trading travelers one healthy cow or horse for two trail-wearied ones.
He fed and rested the tired animals and the following season traded them again. This is. Grant started using the Deer Lodge Valley in 1857 to graze his cattle during the winter along the banks of the Clark Fork river near Cottonwood creek. In 1859 he decided to permanently locate a ranch and constructed a permanent residence in 1862, he convinced traders to settle around him. Johnny was successful, but found that when gold miners arrived in the area, he was at a disadvantage, because he spoke French and the newcomers spoke English, he felt that he could no longer be successful in the area. In August 1866, he sold his ranch to a cattle baron, Conrad Kohrs, for $19,200 and returned to Canada. Conrad Kohrs was born on August 5, 1835, in Wewelsfleth, in Holstein province, a part of the German Confederation. At the age of 22, he became a citizen of the United States, he went to California during the gold rush days. He moved on to Canada and arrived at the gold camps of Montana in 1862, he never struck gold.
Kohrs built his cattle operation until he owned 50,000 head of cattle and had grazing pasture of 10 million acres. However, he had a setback when the severe winter of 1886–1887 left over half the cattle population in the northwest dead. Most cattlemen went bankrupt, but Kohrs managed to receive a 100,000 dollar loan from his banker, A. J. Davis. While the open range era was ending, Kohrs adapted and was able to pay off the loan in only four years. Kohrs and his half-brother, John Bielenberg, turned to more modern methods of ranching, including buying purebred breeding stock, fencing his rangeland and raising and storing fodder, his became known as "Montana's Cattle King." Bielenberg helped Kohrs to run the Grant-Kohrs ranch. He came to Montana at age 18 in 1864 to help with the butcher shop that served the mining camps. Bielenberg had a lot to do with the horse side of the Grant-Kohrs ranch, he bred what were called the "Big Circle" horses, reputed to be able to cover twenty miles of country in a half a day.
Together and Kohrs made a most successful team for over half a century. The winter of 1886–1887 was one of the harshest on record in Montana. Ranchers using the open range for their herds lost upwards of 90% of their cattle to brutal cold and lack of feed. In Eastern Montana, temperatures hovered at 30–40 degrees below zero for weeks on end; the summer of 1887 witnesses a great many ranchers in Montana go out of business. In the 1960s, the National Park Service, under the leadership of Director Conrad Wirth, reenergized the search for historic properties under the auspices of the Historic Sites Act of 1935 and Mission 66; the original Grant-Kohrs ranch was among several other ranches which were recommended for National Historic Landmark status. Con Warren wanted to sell the Grant-Kohrs portion of his ranch to the National Park Service as a historic landmark. In 1970 an agreement to sell the property to the park service was achieved with the proviso that it would be managed as a living ranch by the National Park Service.
The original purchase involved 130 acres of the active Warren Hereford Ranch. In December 1970, the National Park Foundation acquired an additional 1,180 acres of the ranch allowing the National Park Service to take administrative control of the site. In August 1972, the U. S. Congress authorized the establishment of Grant-Kohrs Ranch National Historic Site to provide an understanding of the frontier cattle era of the Nation’s history, to preserve the Grant-Kohrs Ranch, to interpret the nationally significant values thereof for the benefit and inspiration of future generations. In 1972 the National Park Foundation transferred ownership of its portions of the site to the National Park Service; the site was administered under the jurisdiction of Yellowstone National Park. In 1972 the Grant-Kohrs Ranch National Historic Site was administratively listed on the National Register of Historic Places. Throughout the 1970s, the National Park Service continued to acquire acreage from Conrad Warren, rehabilitate elements of the ranch and provide improvements for visitation to include a visitor center, interpretive trails and access for the public.
In 1974 the site became an independently operating unit of the National Park Service with its own superintendent and budget
Cadmium is a chemical element with symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Like zinc, it demonstrates oxidation state +2 in most of its compounds, like mercury, it has a lower melting point than the transition metals in groups 3 through 11. Cadmium and its congeners in group 12 are not considered transition metals, in that they do not have filled d or f electron shells in the elemental or common oxidation states; the average concentration of cadmium in Earth's crust is between 0.5 parts per million. It was discovered in 1817 by Stromeyer and Hermann, both in Germany, as an impurity in zinc carbonate. Cadmium is a byproduct of zinc production. Cadmium was used for a long time as a corrosion-resistant plating on steel, cadmium compounds are used as red and yellow pigments, to color glass, to stabilize plastic. Cadmium use is decreasing because it is toxic and nickel-cadmium batteries have been replaced with nickel-metal hydride and lithium-ion batteries.
One of its few new uses is cadmium telluride solar panels. Although cadmium has no known biological function in higher organisms, a cadmium-dependent carbonic anhydrase has been found in marine diatoms. Cadmium is a soft, ductile, bluish-white divalent metal, it forms complex compounds. Unlike most other metals, cadmium is resistant to corrosion and is used as a protective plate on other metals; as a bulk metal, cadmium is not flammable. Although cadmium has an oxidation state of +2, it exists in the +1 state. Cadmium and its congeners are not always considered transition metals, in that they do not have filled d or f electron shells in the elemental or common oxidation states. Cadmium burns in air to form brown amorphous cadmium oxide. Hydrochloric acid, sulfuric acid, nitric acid dissolve cadmium by forming cadmium chloride, cadmium sulfate, or cadmium nitrate; the oxidation state +1 can be produced by dissolving cadmium in a mixture of cadmium chloride and aluminium chloride, forming the Cd22+ cation, similar to the Hg22+ cation in mercury chloride.
Cd + CdCl2 + 2 AlCl3 → Cd22The structures of many cadmium complexes with nucleobases, amino acids, vitamins have been determined. Occurring cadmium is composed of 8 isotopes. Two of them are radioactive, three are expected to decay but have not done so under laboratory conditions; the two natural radioactive isotopes are 116Cd. The other three are 106Cd, 108Cd, 114Cd. At least three isotopes – 110Cd, 111Cd, 112Cd – are stable. Among the isotopes that do not occur the most long-lived are 109Cd with a half-life of 462.6 days, 115Cd with a half-life of 53.46 hours. All of the remaining radioactive isotopes have half-lives of less than 2.5 hours, the majority have half-lives of less than 5 minutes. Cadmium has 8 known meta states, with the most stable being 113mCd, 115mCd, 117mCd; the known isotopes of cadmium range in atomic mass from 94.950 u to 131.946 u. For isotopes lighter than 112 u, the primary decay mode is electron capture and the dominant decay product is element 47. Heavier isotopes decay through beta emission producing element 49.
One isotope of cadmium, 113Cd, absorbs neutrons with high selectivity: With high probability, neutrons with energy below the cadmium cut-off will be absorbed. The cadmium cut-off is about 0.5 eV, neutrons below that level are deemed slow neutrons, distinct from intermediate and fast neutrons. Cadmium is created via the s-process in low- to medium-mass stars with masses of 0.6 to 10 solar masses, over thousands of years. In that process, a silver atom captures a neutron and undergoes beta decay. Cadmium was discovered in 1817 by Friedrich Stromeyer and Karl Samuel Leberecht Hermann, both in Germany, as an impurity in zinc carbonate. Stromeyer found the new element as an impurity in zinc carbonate, for 100 years, Germany remained the only important producer of the metal; the metal was named after the Latin word for calamine. Stromeyer noted that some impure samples of calamine changed color when heated but pure calamine did not, he was persistent in studying these results and isolated cadmium metal by roasting and reducing the sulfide.
The potential for cadmium yellow as pigment was recognized in the 1840s, but the lack of cadmium limited this application. Though cadmium and its compounds are toxic in certain forms and concentrations, the British Pharmaceutical Codex from 1907 states that cadmium iodide was used as a medication to treat "enlarged joints, scrofulous glands, chilblains". In 1907, the International Astronomical Union defined the international ångström in terms of a red cadmium spectral line. This
The term stained glass can refer to coloured glass as a material or to works created from it. Throughout its thousand-year history, the term has been applied exclusively to the windows of churches and other significant religious buildings. Although traditionally made in flat panels and used as windows, the creations of modern stained glass artists include three-dimensional structures and sculpture. Modern vernacular usage has extended the term "stained glass" to include domestic lead light and objects d'art created from foil glasswork exemplified in the famous lamps of Louis Comfort Tiffany; as a material stained glass is glass, coloured by adding metallic salts during its manufacture. The coloured glass is crafted into stained glass windows in which small pieces of glass are arranged to form patterns or pictures, held together by strips of lead and supported by a rigid frame. Painted details and yellow stain are used to enhance the design; the term stained glass is applied to windows in which the colours have been painted onto the glass and fused to the glass in a kiln.
Stained glass, as an art and a craft, requires the artistic skill to conceive an appropriate and workable design, the engineering skills to assemble the piece. A window must fit snugly into the space for which it is made, must resist wind and rain, especially in the larger windows, must support its own weight. Many large windows have withstood the test of time and remained intact since the Late Middle Ages. In Western Europe they constitute the major form of pictorial art to have survived. In this context, the purpose of a stained glass window is not to allow those within a building to see the world outside or primarily to admit light but rather to control it. For this reason stained glass windows have been described as "illuminated wall decorations"; the design of a window may be figurative. Windows within a building may be thematic, for example: within a church – episodes from the life of Christ. Stained glass is still popular today, but referred to as art glass, it is prevalent in luxury homes, commercial buildings, places of worship.
Artists and companies are contracted to create beautiful art glass ranging from domes, backsplashes, etc. During the late medieval period, glass factories were set up where there was a ready supply of silica, the essential material for glass manufacture. Silica requires a high temperature to melt, something not all glass factories were able to achieve; such materials as potash and lead can be added to lower the melting temperature. Other substances, such as lime, are added to rebuild the weakened network and make the glass more stable. Glass is coloured by adding metallic oxide powders or finely divided metals while it is in a molten state. Copper oxides produce green or bluish green, cobalt makes deep blue, gold produces wine red and violet glass. Much modern red glass is produced using copper, less expensive than gold and gives a brighter, more vermilion shade of red. Glass coloured while in the clay pot in the furnace is known as pot metal glass, as opposed to flashed glass. Using a blow-pipe, a "gather" of molten glass is taken from the pot heating in the furnace.
The gather is formed to a bubble of air blown into it. Using metal tools, molds of wood that have been soaking in water, gravity, the gather is manipulated to form a long, cylindrical shape; as it cools, it is reheated. During the process, the bottom of the cylinder is removed. Once brought to the desired size it is left to cool. One side of the cylinder is opened, it is put into another oven to heat and flatten it, placed in an annealer to cool at a controlled rate, making the material more stable. "Hand-blown" cylinder and crown glass were the types used in ancient stained-glass windows. Stained glass windows were in churches and chapels as well as many more well respected buildings; this hand-blown glass is created by blowing a bubble of air into a gather of molten glass and spinning it, either by hand or on a table that revolves like a potter's wheel. The centrifugal force causes the molten bubble to flatten, it can be cut into small sheets. Glass formed this way can be either coloured and used for stained-glass windows, or uncoloured as seen in small paned windows in 16th- and 17th-century houses.
Concentric, curving waves are characteristic of the process. The center of each piece of glass, known as the "bull's-eye", is subject to less acceleration during spinning, so it remains thicker than the rest of the sheet, it has the distinctive lump of glass left by the "pontil" rod, which holds the glass as it is spun out. This lumpy, refractive quality means the bulls-eyes are less transparent, but they have still been used for windows, both domestic and ecclesiastical. Crown glass is still made today, but not on a large scale. Rolled glass is produced by pouring molten glass onto a metal or graphite table and rolling it into a sheet using a large metal cylinder, similar to rolling out a pie crust; the rolling can be done by machine. Glass can be "double rolled", which means it is passed through two cylinders at once to yield glass of a specified thickness (typically about 1/8" or
Brickwork is masonry produced by a bricklayer, using bricks and mortar. Rows of bricks—called courses— are laid on top of one another to build up a structure such as a brick wall. Bricks may be differentiated from blocks by size. For example, in the UK a brick is defined as a unit having dimensions less than 337.5x225x112.5mm and a block is defined as a unit having one or more dimensions greater than the largest possible brick. Brick is a popular medium for constructing buildings, examples of brickwork are found through history as far back as the Bronze Age; the fired-brick faces of the ziggurat of ancient Dur-Kurigalzu in Iraq date from around 1400 BC, the brick buildings of ancient Mohenjo-daro in Pakistan were built around 2600 BC. Much older examples of brickwork made with dried bricks may be found in such ancient locations as Jericho in Judea, Çatal Hüyük in Anatolia, Mehrgarh in Pakistan; these structures have survived from the Stone Age to the present day. Brick dimensions are expressed in construction or technical documents in two ways as co-ordinating dimensions and working dimensions.
Coordination dimensions are the actual physical dimensions of the brick with the mortar required on one header face, one stretcher face and one bed. Working dimensions is the size of a manufactured brick, it is called the nominal size of a brick. Brick size may be different due to shrinkage or distortion due to firing etc. An example of a co-ordinating metric used for bricks in the UK is as follows: Bricks of dimensions 215 mm × 102.5 mm × 65 mm. In this case the co-ordinating metric works because the length of a single brick is equal to the total of the width of a brick plus a perpend plus the width of a second brick. There are many other brick sizes worldwide, many of them use this same co-ordinating principle; as the most common bricks are cuboids, six surfaces are named as followed: Top and bottom surfaces are called Beds Ends or narrow surfaces are called Headers or header faces Sides or wider surfaces are called Stretchers or stretcher faces Mortar placed between bricks is given separate names with respect to their position.
Mortar placed horizontally below or top of a brick is called a bed, mortar Placed vertically between bricks is called a perpend. A brick made with just rectilinear dimensions is called a solid brick. Bricks might have a depression on a single bed; the depression is called a frog, the bricks are known as frogged bricks. Frogs should never exceed 20 % of the total volume of the brick. Cellular bricks have depressions exceeding 20% of the volume of the brick. Perforated bricks have holes through the brick from bed to bed. Most of the building standards and good construction practices recommend the volume of holes should not exceeding 20% of the total volume of the brick. Parts of brickwork include bricks and perpends; the bed is the mortar upon. A perpend is a vertical joint between any two bricks and is usually—but not always—filled with mortar. A brick is given a classification based on how it is laid, how the exposed face is oriented relative to the face of the finished wall. Stretcher or stretching brick A brick laid flat with its long narrow side exposed.
Header or heading brick A brick laid flat with its width exposed. Soldier A brick laid vertically with its long narrow side exposed. Sailor A brick laid vertically with the broad face of the brick exposed. Rowlock A brick laid on the long narrow side with the short end of the brick exposed. Shiner or rowlock stretcher A brick laid on the long narrow side with the broad face of the brick exposed; the practice of laying uncut full-sized bricks wherever possible gives brickwork its maximum possible strength. In the diagrams below, such uncut full-sized bricks are coloured as follows: Stretcher HeaderOccasionally though a brick must be cut to fit a given space, or to be the right shape for fulfilling some particular purpose such as generating an offset—called a lap—at the beginning of a course. In some cases these special shapes or sizes are manufactured. In the diagrams below, some of the cuts most used for generating a lap are coloured as follows: Three-quarter bat, stretching A brick cut to three-quarters of its length, laid flat with its long, narrow side exposed.
Three-quarter bat, heading A brick cut to three-quarters of its length, laid flat with its short side exposed. Half bat A brick cut in half across its length, laid flat. Queen closer A brick cut in half down its width, laid with its smallest face exposed and standing vertically. A queen closer is used for the purpose of creating a lap. Less used cuts are all coloured as follows: Quarter bat A brick cut to a quarter of its length. Three-quarter queen closer A queen closer cut to three-quarters of its length. King closer A brick with one corner cut away. A nearly universal rule in brickwork is. Walls, extending upwards, can be of varying depth or thickness; the bricks are laid running linearly and extending upwards, forming wythes or leafs. It is as important; the dominant method for consolidating the leaves together was to lay bricks across them, rather than running linearly. Brickwork observing either or both of these two conventions is described as being laid in one or another bond. A leaf is as thick as the width of one brick, but a wall is said to be one brick thick if it as wide as the length of a brick.
Accordingly, a single-leaf wall