Sergey Mikhaylovich Prokudin-Gorsky was a Russian chemist and photographer. He is best known for his pioneering work in colour photography and his effort to document early 20th-century Russia. Using a railroad-car darkroom provided by Tsar Nicholas II, Prokudin-Gorsky traveled the Russian Empire from around 1909 to 1915 using his three-image colour photography to record its many aspects. While some of his negatives were lost, the majority ended up in the U. S. Library of Congress after his death. Starting in 2000, the negatives were digitised and the colour triples for each subject digitally combined to produce hundreds of high-quality colour images of century-ago Russia. Prokudin-Gorsky was born in Murom in the ancestral estate of Funikova Gora, in what is now Kirzhachsky District, Vladimir Oblast, his parents were of the Russian nobility, the family had a long military history. They moved to Saint Petersburg, where Prokudin-Gorsky enrolled in Saint Petersburg State Institute of Technology to study chemistry under Dmitri Mendeleev.
He studied music and painting at the Imperial Academy of Arts. In 1890, Prokudin-Gorsky married Anna Aleksandrovna Lavrova, the couple had two sons and Dmitri, a daughter, Ekaterina. Anna was the daughter of the Russian industrialist Aleksandr Stepanovich Lavrov, an active member in the Imperial Russian Technical Society. Prokudin-Gorsky subsequently became the director of the executive board of Lavrov's metal works near Saint Petersburg and remained so until the October Revolution, he joined Russia's oldest photographic society, the photography section of the IRTS, presenting papers and lecturing on the science of photography. In 1901, he established a photography laboratory in Saint Petersburg. In 1902, he traveled to Berlin and spent six weeks studying colour sensitization and three-colour photography with photochemistry professor Adolf Miethe, the most advanced practitioner in Germany at that time. Throughout the years, Prokudin-Gorsky's photographic work and slide shows to other scientists and photographers in Russia and France earned him praise, in 1906 he was elected the president of the IRTS photography section and editor of Russia's main photography journal, the Fotograf-Liubitel.
Gorsky was a member of the Royal Photographic Society between 1920 and 1932.. Prokudin-Gorsky's best-known work during his lifetime was his color portrait of Leo Tolstoy, reproduced in various publications, on postcards, as larger prints for framing; the fame from this photo and his earlier photos of Russia's nature and monuments earned him invitations to show his work to the Russian Grand Duke Michael Alexandrovich and Dowager Empress Maria Feodorovna in 1908, to Tsar Nicholas II and his family in 1909. The Tsar enjoyed the demonstration, with his blessing, Prokudin-Gorsky got the permission and funding to document Russia in color. In the course of ten years, he was to make a collection of 10,000 photos. Prokudin-Gorsky considered the project his life's work and continued his photographic journeys through Russia until after the October Revolution, he was appointed to a new professorship under the new regime, but he left the country in August 1918. He still pursued scientific work in color photography, published papers in English photography journals and, together with his colleague S. O. Maksimovich, obtained patents in Germany, England and Italy.
In 1920, Prokudin-Gorsky remarried and had a daughter with his assistant Maria Fedorovna née Schedrimo. The family settled in Paris in 1922, reuniting with his first wife and children. Prokudin-Gorsky set up a photo studio there together with his three adult children, naming it after his fourth child, Elka. In the 1930s, the elderly Prokudin-Gorsky continued with lectures showing his photographs of Russia to young Russians in France, but stopped commercial work and left the studio to his children, who named it Gorsky Frères, he died in Paris on September 1944, a month after the Liberation of Paris. He is buried in the Sainte-Geneviève-des-Bois Russian Cemetery; the method of color photography used by Prokudin-Gorsky was first suggested by James Clerk Maxwell in 1855 and demonstrated in 1861, but good results were not possible with the photographic materials available at that time. In imitation of the way a normal human eye senses color, the visible spectrum of colors was divided into three channels of information by capturing it in the form of three black-and-white photographs, one taken through a red filter, one through a green filter, one through a blue filter.
The resulting three photographs could be projected through filters of the same colors and superimposed on a screen, synthesizing the original range of color additively. The first person to demonstrate good results by this method was Frederic E. Ives, whose "Kromskop" system of viewers and camera equipment was commercially available from 1897 until about 1907. Only the viewers and ready-made triple photographs for use in them sold in any significant quantity. Still life arrangements, unpopulated landscapes and oil paintings were the typical subject matter, but a few examples of color portraiture from life were offered. Several Kromskop color views of the aftermath of the 190
Jersey the Bailiwick of Jersey, is a Crown dependency located near the coast of Normandy, France. It is the second closest of the Channel Islands to France, after Alderney. Jersey was part of the Duchy of Normandy, whose dukes went on to become kings of England from 1066. After Normandy was lost by the kings of England in the 13th century, the ducal title surrendered to France and the other Channel Islands remained attached to the English crown; the bailiwick consists of the island of Jersey, the largest of the Channel Islands, along with surrounding uninhabited islands and rocks collectively named Les Dirouilles, Les Écréhous, Les Minquiers, Les Pierres de Lecq, other reefs. Although the bailiwicks of Jersey and Guernsey are referred to collectively as the Channel Islands, the "Channel Islands" are not a constitutional or political unit. Jersey has a separate relationship to the Crown from the other Crown dependencies of Guernsey and the Isle of Man, although all are held by the monarch of the United Kingdom.
Jersey is a self-governing parliamentary democracy under a constitutional monarchy, with its own financial and judicial systems, the power of self-determination. The Lieutenant Governor on the island is the personal representative of the Queen. Jersey is not part of the United Kingdom, has an international identity separate from that of the UK, but the UK is constitutionally responsible for the defence of Jersey; the definition of United Kingdom in the British Nationality Act 1981 is interpreted as including the UK and the Islands together. The European Commission have confirmed in a written reply to the European Parliament in 2003 that Jersey is within the Union as a European Territory for whose external relationships the UK is responsible. Jersey is not part of the European Union but has a special relationship with it, notably being treated as within the European Community for the purposes of free trade in goods. British cultural influence on the island is evident in its use of English as the main language and the British pound as its primary currency if some people still speak the Norman language.
Additional cultural commonalities include driving on the left, access to the BBC and ITV regions, a school curriculum following that of England, the popularity of British sports, including cricket. The Channel Islands are mentioned in the Antonine Itinerary as the following: Sarnia, Barsa and Andium, but Jersey cannot be identified because none corresponds directly to the present names; the name Caesarea has been used as the Latin name for Jersey since William Camden's Britannia, is used in titles of associations and institutions today. The Latin name Caesarea was applied to the colony of New Jersey as Nova Caesarea. Andium and Augia were used in antiquity. Scholars variously surmise that Jersey and Jèrri derive from jarð or jarl, or a personal name, Geirr; the ending -ey denotes an island. Jersey history is influenced by its strategic location between the northern coast of France and the southern coast of England. La Cotte de St Brelade is a Palaeolithic site inhabited before rising sea levels transformed Jersey into an island.
Jersey was a centre of Neolithic activity. Evidence of Bronze Age and early Iron Age settlements can be found in many locations around the island. Additional archaeological evidence of Roman influence has been found, in particular at Les Landes, the coastal headland site at Le Pinacle, where remains of a primitive structure are attributed to Gallo-Roman temple worship. Jersey was part of Neustria with the same Gallo-Frankish population as the continental mainland. Jersey, the whole Channel Islands and the Cotentin peninsula came under the control of the duke of Brittany during the Viking invasions, because the king of the Franks was unable to defend them, however they remained in the archbishopric of Rouen. Jersey was invaded by Vikings in the 9th century. In 933 it was annexed to the future Duchy of Normandy, together with the other Channel Islands and Avranchin, by William Longsword, count of Rouen and it became one of the Norman Islands; when William's descendant, William the Conqueror, conquered England in 1066, the Duchy of Normandy and the kingdom of England were governed under one monarch.
The Dukes of Normandy owned considerable estates in the island, Norman families living on their estates established many of the historical Norman-French Jersey family names. King John lost all his territories in mainland Normandy in 1204 to King Philip II Augustus, but retained possession of Jersey and the other Channel Islands. In the Treaty of Paris, the English king formally surrendered his claim to the duchy of Normandy and ducal title, since the islands have been internally self-governing territories of the English crown and latterly the British crown. On 7 October 1406, 1,000 French men at arms led by Pero Niño invaded Jersey, landing at St Aubin's Bay and defeated the 3,000 defenders but failed to capture the island. In the late 16th century, islanders travelled across the North Atlantic to participate in the Newfoundland fisheries. In recognition for help given to him during his exile in Jersey in the 1640s, King Charles II of England gave Vice Admiral Sir George Carteret and governor, a large grant of land in the American colonies in between the Hudson and Delaware rivers, which he promptly named New Jersey.
It is now a state in the Unit
Albert, Prince Consort
Prince Albert of Saxe-Coburg and Gotha was the husband of Queen Victoria. He was born in the Saxon duchy of Saxe-Coburg-Saalfeld, to a family connected to many of Europe's ruling monarchs. At the age of 20, he married Queen Victoria, he felt constrained by his role of prince consort, which did not afford him power or responsibilities. He developed a reputation for supporting public causes, such as educational reform and the abolition of slavery worldwide, was entrusted with running the Queen's household and estates, he was involved with the organisation of the Great Exhibition of 1851, a resounding success. Victoria came to depend more on his support and guidance, he aided the development of Britain's constitutional monarchy by persuading his wife to be less partisan in her dealings with Parliament—although he disagreed with the interventionist foreign policy pursued during Lord Palmerston's tenure as Foreign Secretary. Albert died at the young age of 42. Victoria was so devastated at the loss of her husband that she entered into a deep state of mourning and wore black for the rest of her life.
On her death in 1901, their eldest son succeeded as Edward VII, the first British monarch of the House of Saxe-Coburg and Gotha, named after the ducal house to which Albert belonged. Albert was born at Schloss Rosenau, near Coburg, the second son of Ernest III, Duke of Saxe-Coburg-Saalfeld, his first wife, Louise of Saxe-Gotha-Altenburg. Albert's future wife, was born earlier in the same year with the assistance of the same midwife, Charlotte von Siebold. Albert was baptised into the Lutheran Evangelical Church on 19 September 1819 in the Marble Hall at Schloss Rosenau with water taken from the local river, the Itz, his godparents were the Dowager Duchess of Saxe-Coburg-Saalfeld. In 1825, Albert's great-uncle, Frederick IV, Duke of Saxe-Gotha-Altenburg, died, his death led to a realignment of Saxon duchies the following year and Albert's father became the first reigning duke of Saxe-Coburg and Gotha. Albert and his elder brother, spent their youth in a close companionship marred by their parents' turbulent marriage and eventual separation and divorce.
After their mother was exiled from court in 1824, she married her lover, Alexander von Hanstein, Count of Polzig and Beiersdorf. She never saw her children again, died of cancer at the age of 30 in 1831; the following year, their father married his sons' cousin Princess Marie of Württemberg. The brothers were educated at home by Christoph Florschütz and studied in Brussels, where Adolphe Quetelet was one of their tutors. Like many other German princes, Albert attended the University of Bonn, where he studied law, political economy and the history of art, he played music and excelled at sport fencing and riding. His tutors at Bonn included the poet Schlegel; the idea of marriage between Albert and his cousin, was first documented in an 1821 letter from his paternal grandmother, the Dowager Duchess of Saxe-Coburg-Saalfeld, who said that he was "the pendant to the pretty cousin". By 1836, this idea had arisen in the mind of their ambitious uncle Leopold, King of the Belgians since 1831. At this time, Victoria was the heir presumptive to the British throne.
Her father, Prince Edward, Duke of Kent and Strathearn, the fourth son of King George III, had died when she was a baby, her elderly uncle, King William IV, had no legitimate children. Her mother, the Duchess of Kent, was the sister of both Albert's father—the Duke of Saxe-Coburg and Gotha—and King Leopold. Leopold arranged for his sister, Victoria's mother, to invite the Duke of Saxe-Coburg and Gotha and his two sons to visit her in May 1836, with the purpose of meeting Victoria. William IV, disapproved of any match with the Coburgs, instead favoured the suit of Prince Alexander, second son of the Prince of Orange. Victoria was well aware of the various matrimonial plans and critically appraised a parade of eligible princes, she wrote, " is handsome. Alexander, on the other hand, she described as "very plain". Victoria wrote to her uncle Leopold to thank him "for the prospect of great happiness you have contributed to give me, in the person of dear Albert... He possesses every quality that could be desired to render me happy."
Although the parties did not undertake a formal engagement, both the family and their retainers assumed that the match would take place. Victoria came to the throne aged eighteen on 20 June 1837, her letters of the time show interest in Albert's education for the role he would have to play, although she resisted attempts to rush her into marriage. In the winter of 1838–39, the prince visited Italy, accompanied by the Coburg family's confidential adviser, Baron Stockmar. Albert returned to the United Kingdom with Ernest in October 1839 to visit the Queen, with the objective of settling the marriage. Albert and Victoria felt mutual affection and the Queen proposed to him on 15 October 1839. Victoria's intention to marry was declared formally to the Privy Council on 23 November, the couple married on
Additive color, or "additive mixing", is a property of a color model that predicts the appearance of colors made by coincident component lights with distinct colors, i.e. the perceived color can be predicted by summing the numeric representations of the component colors. Modern formulations of Grassmann's laws describe the additivity in the color perception of light mixtures in terms of algebraic equations, it is important note that additive color predicts perception and not any sort of change in the photons of light themselves. These predictions are only applicable in the limited scope of color matching experiments where viewers match small patches of uniform color isolated against a grey or black background. Additive color models are applied in the design and testing of electronic displays that are used to render realistic images containing diverse sets of color using phosphors that emit light of a limited set of primary colors. Examination with a sufficiently powerful magnifying lens will reveal that each pixel in CRT, LCD, most other types of color video displays is composed of red and blue light emitting phosphors which appear as a variety of single colors when viewed from a normal distance.
Additive color does not, predict the appearance of mixtures of printed color inks, dye layers in typical color photographs on film or paint mixtures. Subtractive color, is used to model the appearance of color from pigments or dyes, such as those in paints and the three dye layers in typical color photographs on film; the combination of two of the common three additive primary colors in equal proportions produces an additive secondary color—cyan, magenta or yellow. Additive color is used to predict colors from overlapping projected colored lights used in theatrical lighting for plays, circus shows, night clubs; the full gamut of color available in any additive color system is defined by all the possible combinations of all the possible luminosities of each primary color in that system. In chromaticity space, the gamut is a plane convex polygon with corners at the primaries. For three primaries, it is a triangle. Systems of additive color are motivated by the Young–Helmholtz theory of trichromatic color vision, articulated around 1850 by Hermann von Helmholtz, based on earlier work by Thomas Young.
For his experimental work on the subject, James Clerk Maxwell is sometimes credited as being the father of additive color. He had the photographer Thomas Sutton photograph a tartan ribbon on black-and-white film three times, first with a red green blue color filter over the lens; the three black-and-white images were developed and projected onto a screen with three different projectors, each equipped with the corresponding red, green, or blue color filter used to take its image. When brought into alignment, the three images formed a full color image, thus demonstrating the principles of additive color. Color mixing Color space Color theory Color motion picture film Kinemacolor Prizma Color RGB color model Subtractive color Technicolor William Friese-Greene RGB and CMYK Colour systems. Http://www.edinphoto.org.uk/1_P/1_photographers_maxwell.htm - Photos and stories from the James Clerk Maxwell Foundation. Stanford University CS 178 interactive Flash demo comparing additive and subtractive color mixing
An optical filter is a device that selectively transmits light of different wavelengths implemented as a glass plane or plastic device in the optical path, which are either dyed in the bulk or have interference coatings. The optical properties of filters are described by their frequency response, which specifies how the magnitude and phase of each frequency component of an incoming signal is modified by the filter. Filters belong to one of two categories; the simplest, physically, is the absorptive filter. Optical filters selectively transmit light in a particular range of wavelengths, that is, while absorbing the remainder, they can pass long wavelengths only, short wavelengths only, or a band of wavelengths, blocking both longer and shorter wavelengths. The passband may be wider. There are filters with more complex transmission characteristic, for example with two peaks rather than a single band. Optical filters are used in photography, in many optical instruments, to colour stage lighting. In astronomy optical filters are used to restrict light passed to the spectral band of interest, e.g. to study infrared radiation without visible light which would affect film or sensors and overwhelm the desired infrared.
Optical filters are essential in fluorescence applications such as fluorescence microscopy and fluorescence spectroscopy. Photographic filters are a particular case of optical filters, much of the material here applies. Photographic filters do not need the controlled optical properties and defined transmission curves of filters designed for scientific work, sell in larger quantities at correspondingly lower prices than many laboratory filters; some photographic effect filters, such as star effect filters, are not relevant to scientific work. Absorptive filters are made from glass to which various inorganic or organic compounds have been added; these compounds absorb some wavelengths of light while transmitting others. The compounds can be added to plastic to produce gel filters, which are lighter and cheaper than glass-based filters. Alternately, dichroic filters can be made by coating a glass substrate with a series of optical coatings. Dichroic filters reflect the unwanted portion of the light and transmit the remainder.
Dichroic filters use the principle of interference. Their layers form a sequential series of reflective cavities that resonate with the desired wavelengths. Other wavelengths destructively reflect as the peaks and troughs of the waves overlap. Dichroic filters are suited for precise scientific work, since their exact colour range can be controlled by the thickness and sequence of the coatings, they are much more expensive and delicate than absorption filters. They can be used in devices such as the dichroic prism of a camera to separate a beam of light into different coloured components; the basic scientific instrument of this type is a Fabry–Pérot interferometer. It uses two mirrors to establish a resonating cavity, it passes wavelengths. Etalons are another variation: transparent cubes or fibers whose polished ends form mirrors tuned to resonate with specific wavelengths; these are used to separate channels in telecommunications networks that use wavelength division multiplexing on long-haul optic fibers.
Monochromatic filters only allow a narrow range of wavelengths to pass. The term "infrared filter" can be ambiguous, as it may be applied to filters to pass infrared or to block infrared. Infrared-passing filters pass infrared. Infrared cut-off filters are designed to block or reflect infrared wavelengths but pass visible light. Mid-infrared filters are used as heat-absorbing filters in devices with bright incandescent light bulbs to prevent unwanted heating due to infrared radiation. There are filters which are used in solid state video cameras to block IR due to the high sensitivity of many camera sensors to unwanted near-infrared light. Ultraviolet filters let visible light through; because photographic film and digital sensors are sensitive to ultraviolet but the human eye is not, such light would, if not filtered out, make photographs look different from the scene visible to people, for example making images of distant mountains appear unnaturally hazy. An ultraviolet-blocking filter renders images closer to the visual appearance of the scene.
As with infrared filters there is a potential ambiguity between UV-passing filters. Neutral density filters have a constant attenuation across the range of visible wavelengths, are used to reduce the intensity of light by reflecting or absorbing a portion of it, they are specified by the optical density of the filter, the negative of the common logarithm of the transmission coefficient. They are useful for making photographic exposures longer. A practical example is making
Pwllheli is a community and the main market town of the Llŷn Peninsula in Gwynedd, north-western Wales. It had a population of 4,076 in 2011 of whom 81 %, are Welsh speaking. Pwllheli is the place, it is the birthplace of the Welsh poet Sir Albert Evans-Jones. The town's name means salt water basin; the town was given its charter as a borough by Edward, the Black Prince, in 1355, a market is still held each Wednesday in the centre of the town on'Y Maes'. The town grew around the shipbuilding and fishing industries, the granite quarry at Gimlet Rock. During the 1890s, the town was developed by a Cardiff businessman; this work included the Promenade and houses at West End. A tramway was built linking the town to Llanbedrog; the trams ran until 1927 when the section of track between Carreg-y-Defaid and Tyddyn-Caled was damaged by a storm. Andrews ran the Cardiff Road section in 1928, offered to sell the tramway to Pwllheli Corporation at the end of the season, but they did not take up his offer, he sold the assets, the Corporation removed the tracks during the winter of 1928/29.
For many years a holiday camp run by Butlins operated a few miles from Pwllheli at Pen-y-chain. During the Second World War it became a naval camp, HMS Glendower, it operated a hospital for wounded servicemen at Brynberyl on the Pwllheli to Caernarfon road two miles out of town. After the war, Butlins re-established the holiday camp; the camp, now renamed Hafan y Môr, is now run by the Haven group. Pwllheli is the main town of the Llŷn Peninsula, has a range of shops and other services; as a local railhead with a market every Wednesday, the town is a gathering point for the population of the whole peninsula. Ysgol Cymerau, primary school Ysgol Glan y Môr, secondary school Ysgol Glan y Môr was formed by the merger in 1969 of the former Pwllheli Grammar School at Penrallt and the Frondeg Secondary Modern School in Upper Ala Road, to form a comprehensive school based at two separate sites in the town; the junior pupils were located at the Penrallt site and the senior pupils at a new complex in Cardiff Road.
This new school was subsequently expanded to accommodate all pupils under the Ysgol Glan y Môr name. The Penrallt site was redeveloped as the Pwllheli campus of Coleg Meirion-Dwyfor; the façade of the main building of the old grammar school was retained and incorporated into the design of the current college buildings. Thus the'old school' is seen from the town square as it has been since the former Pwllheli County School moved to Penrallt in the early 20th century. Coleg Meirion-Dwyfor Pwllheli railway station is the terminus of the Cambrian Coast Railway running to Machynlleth with services continuing to Shrewsbury and Birmingham; the station is served by Transport for Wales. The rail link to Caernarfon via the Carnarvonshire Railway was axed under the Beeching cuts and closed in December 1964. Pwllheli is connected to the wider road network by the A497 to Porthmadog and the A499 to Caernarfon. From there, major roads lead away from Gwynedd to the rest of Wales. Bus services in the town are operated by Arriva Buses Wales and Nefyn Coaches and serve most of the town as well as the rest of the wider Llŷn Peninsula area.
Clynnog & Trefor run services to Caernarfon where connections can be made to Bangor and the wider North Wales area. Pwllheli bus station is situated in the town centre. Plas Bodegroes a Michelin starred restaurant Two Blue Flag beaches Penarth Fawr a 15th-century house Marina Hafan y Môr, a former Butlins holiday camp now operated by Haven Pwllheli Market Clwb Golff Pwllheli - a par 69 links and parkland golf course Pwllheli Sailing Club - hosts national and international events Neuadd Dwyfor - theatre and cinema located in Penlan StreetPwllheli has a section of the Wales Coast Path along its shoreline. Pwllheli hosted the National Eisteddfod in 1925 and 1955, as well as an unofficial National Eisteddfod event in 1875. According to the United Kingdom Census 2001, 80% of the population speak Welsh, with the highest percentage of Welsh speakers in the 10-14 age bracket, 94%. Pwllheli is home to association football team Pwllheli F. C. rugby union team Pwllheli RFC and Running Club Llŷn Striders.
Pwllheli is a hub for water sports, due in part to a large and modern marina, Pwllheli Sailing Club, Plas Heli - the Welsh National Sailing Academy. The town has South Beach and Glan don. South Beach stretches from Gimlet Rock, across the Promenade and West End, towards Penrhos and Llanbedrog. Glan don Beach is located on the eastern side of the river mouth and runs for 3 miles from behind the marina workshops and out towards Penychain; the town has a popular golf club, located on the beautiful Llŷn coastline. Official Website for Pwllheli Memories of Butlin's at Pwllheli www.geograph.co.uk: photos of Pwllheli and surrounding area list of ships built at Pwllheli at Rhiw.com
A thought experiment considers some hypothesis, theory, or principle for the purpose of thinking through its consequences. Given the structure of the experiment, it may not be possible to perform it, if it could be performed, there need not be an intention to perform it; the common goal of a thought experiment is to explore the potential consequences of the principle in question: "A thought experiment is a device with which one performs an intentional, structured process of intellectual deliberation in order to speculate, within a specifiable problem domain, about potential consequents for a designated antecedent". Examples of thought experiments include Schrödinger's cat, illustrating quantum indeterminacy through the manipulation of a sealed environment and a tiny bit of radioactive substance, Maxwell's demon, which attempts to demonstrate the ability of a hypothetical finite being to violate the 2nd law of thermodynamics; the ancient Greek δείκνυμι, or thought experiment, "was the most ancient pattern of mathematical proof", existed before Euclidean mathematics, where the emphasis was on the conceptual, rather than on the experimental part of a thought-experiment.
The key experiment in the history of modern science is Galileo's demonstration that falling objects must fall at the same rate regardless of their masses. This is thought to have been a straightforward physical demonstration, involving climbing up the Leaning Tower of Pisa and dropping two heavy weights off it, whereas in fact, it was a logical demonstration, using the'thought experiment' technique. The'experiment' is described by Galileo in Discorsi e dimostrazioni matematiche thus: Salviati. If we take two bodies whose natural speeds are different, it is clear that on uniting the two, the more rapid one will be retarded by the slower, the slower will be somewhat hastened by the swifter. Do you not agree with me in this opinion? Simplicio. You are unquestionably right. Salviati, but if this is true, if a large stone moves with a speed of, eight while a smaller moves with a speed of four when they are united, the system will move with a speed less than eight. Hence the heavier body moves with less speed than the lighter.
Thus you see how, from your assumption that the heavier body moves more than the lighter one, I infer that the heavier body moves more slowly. Although the extract does not convey the elegance and power of the'demonstration' well, it is clear that it is a'thought' experiment, rather than a practical one. Strange as Cohen says, that philosophers and scientists alike refuse to acknowledge either Galileo in particular, or the thought experiment technique in general for its pivotal role in both science and philosophy. Instead, many philosophers prefer to consider'Thought Experiments' to be the use of a hypothetical scenario to help understand the way things are. Thought experiments have been used in a variety of fields, including philosophy, law and mathematics. In philosophy, they have been used at least since some pre-dating Socrates. In law, they were well-known to Roman lawyers quoted in the Digest. In physics and other sciences, notable thought experiments date from the 19th and the 20th century, but examples can be found at least as early as Galileo.
Johann Witt-Hansen established that Hans Christian Ørsted was the first to use the Latin-German mixed term Gedankenexperiment circa 1812. Ørsted was the first to use its German equivalent, Gedankenversuch, in 1820. Much Ernst Mach used the term Gedankenexperiment in a different way, to denote the imaginary conduct of a real experiment that would be subsequently performed as a real physical experiment by his students. Physical and mental experimentation could be contrasted: Mach asked his students to provide him with explanations whenever the results from their subsequent, physical experiment differed from those of their prior, imaginary experiment; the English term thought experiment was coined from Mach's Gedankenexperiment, it first appeared in the 1897 English translation of one of Mach’s papers. Prior to its emergence, the activity of posing hypothetical questions that employed subjunctive reasoning had existed for a long time. However, people had no way of speaking about it; this helps to explain the wide and diverse range of the application of the term "thought experiment" once it had been introduced into English.
Thought experiments, which are well-structured, well-defined hypothetical questions that employ subjunctive reasoning – "What might happen if... " – have been used to pose questions in philosophy at least since Greek antiquity, some pre-dating Socrates. In physics and other sciences many thought experiments date from the 19th and the 20th Century, but examples can be found at least as early as Galileo. In thought experiments we gain new information by rearranging or reorganizing known empirical data in a new way and drawing new inferences from them or by looking at these data from a different and unusual perspective. In Galileo’s thought experiment, for ex