1.
Dorset
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Dorset /ˈdɔːrsᵻt/ is a county in South West England on the English Channel coast. The ceremonial county comprises the county, which is governed by Dorset County Council. Covering an area of 2,653 square kilometres, Dorset borders Devon to the west, Somerset to the north-west, Wiltshire to the north-east, the county town is Dorchester which is in the south. After the reorganisation of government in 1974 the countys border was extended eastward to incorporate the Hampshire towns of Bournemouth. Around half of the lives in the South East Dorset conurbation. The county has a history of human settlement stretching back to the Neolithic era. The Romans conquered Dorsets indigenous Celtic tribe, and during the early Middle Ages, the first recorded Viking raid on the British Isles occurred in Dorset during the eighth century, and the Black Death entered England at Melcombe Regis in 1348. During the Second World War, Dorset was heavily involved in the preparations for the invasion of Normandy, the former was the sailing venue in the 2012 Summer Olympics, and both have clubs or hire venues for sailing, Cornish pilot gig rowing, sea kayaking and powerboating. Dorset has a varied landscape featuring broad elevated chalk downs, steep limestone ridges, over half the county is designated as an Area of Outstanding Natural Beauty. Three-quarters of its coastline is part of the Jurassic Coast Natural World Heritage Site due to its geological and it features notable landforms such as Lulworth Cove, the Isle of Portland, Chesil Beach and Durdle Door. Agriculture was traditionally the major industry of Dorset but is now in decline, there are no motorways in Dorset but a network of A roads cross the county and two railway main lines connect to London. Dorset has ports at Poole, Weymouth and Portland, and an international airport, the county has a variety of museums, theatres and festivals, and is host to one of Europes largest outdoor shows. It is the birthplace of Thomas Hardy, who used the county as the setting of his novels. Dorset derives its name from the county town of Dorchester, the Romans established the settlement in the 1st century and named it Durnovaria which was a Latinised version of a Common Brittonic word possibly meaning place with fist-sized pebbles. It is first mentioned in the Anglo-Saxon Chronicle in AD845 and in the 10th century the countys archaic name, the first human visitors to Dorset were Mesolithic hunters, from around 8000 BC. The first permanent Neolithic settlers appeared around 3000 BC and were responsible for the creation of the Dorset Cursus, from 2800 BC onwards Bronze Age farmers cleared Dorsets woodlands for agricultural use and Dorsets high chalk hills provided a location for numerous round barrows. During the Iron Age, the British tribe known as the Durotriges established a series of forts across the county—most notably Maiden Castle which is one of the largest in Europe. The Romans arrived in Dorset during their conquest of Britain in AD43, Maiden Castle was captured by a Roman legion under the command of Vespasian, and the Roman settlement of Durnovaria was established nearby
2.
Lacock
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Lacock is a village and civil parish in the county of Wiltshire, England,3 miles from the town of Chippenham. The village is owned almost in its entirety by the National Trust, the parish includes Bowden Hill, a small village 1 mile to the east of Lacock, and the hamlet of Notton, the same distance to the northwest. Lacock is mentioned in the Domesday Book, with a population of 160–190, Lacock Abbey was founded on the manorial lands by Ela, Countess of Salisbury and established in 1232, and the village — with the manor — formed its endowment to God and St Mary. Lacock was granted a market and developed a thriving industry during the Middle Ages. Reybridge, and a ford, remained the only crossing points of the River Avon until the 18th century. At the dissolution, the Abbey and estate, including the village were sold to William Sharington, most of the surviving houses are 18th century or earlier in construction. There is a 14th century tithe barn, the medieval St Cyriacs Church, an inn dating from the 15th century, in 1916 Charles Henry Fox Talbot bequeathed the Lacock estate to his niece, Matilda Gilchrist-Clark, who took the name of Talbot. The estate – comprising 284 acres, the Abbey and the village – was given to the National Trust in 1944 by Matilda Talbot. Lacock has two houses and a number of shops in its High Street including a grocery store, a bakery, gift shops. The village has used as a film and television set, notably for the 1995 BBC production of Pride and Prejudice. It has also made appearances in the Harry Potter films Harry Potter and the Philosophers Stone and Harry Potter. In the spring of 2012, it was a location for the fantasy adventure film Mariah Mundi. Most recently it was used for the series of Downton Abbey. A scarecrow festival is annually in Lacock and is popular with visitors from the local area. All monies raised are donated to Lacock Primary School, Lacock has a small primary school with 75 pupils
3.
Salt print
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The salt print was the dominant paper-based photographic process for producing positive prints during the period from 1839 through approximately 1860. The salted paper technique was created in the mid-1830s by English scientist and this produced a tenacious coating of silver chloride in an especially light-sensitive chemical condition. The paper darkened where it was exposed to light, in 1839, washing with a solution of sodium thiosulfate was found to be the most effective way to make the results truly light-fast. The salt print process is often confused with Talbots slightly later calotype or talbotype process and this made calotype paper far more practical for use in a camera. Salted paper typically required at least an hour of exposure in the camera to yield a negative showing much more than objects silhouetted against the sky
4.
Calotype
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Calotype or talbotype is an early photographic process introduced in 1841 by William Henry Fox Talbot, using paper coated with silver iodide. The term calotype comes from the Greek καλός, beautiful, and τύπος, Talbot made his first successful camera photographs in 1835 using paper sensitised with silver chloride, which darkened in proportion to its exposure to light. This early photogenic drawing process was a process, i. e. the paper had to be exposed in the camera until the image was fully visible. A very long exposure—typically an hour or more—was required to produce an acceptable negative, the paper, shielded from further exposure to daylight, was then removed from the camera and the latent image was chemically developed into a fully visible image. This major improvement was introduced to the public as the calotype or talbotype process in 1841, the light-sensitive silver halide in calotype paper was silver iodide, created by the reaction of silver nitrate with potassium iodide. At this stage, the balance of the chemicals was such that the paper was practically insensitive to light, development was effected by brushing on more of the gallo-nitrate of silver solution while gently warming the paper. The calotype process produced a translucent original negative image from which multiple positives could be made by contact printing. This gave it an important advantage over the process, which produced an opaque original positive that could only be duplicated by copying it with a camera. Although calotype paper could be used to make prints from calotype negatives, Talbots earlier silver chloride paper. It was simpler and less expensive, and Talbot himself considered the appearance of salted paper prints to be more attractive, the longer exposure required to make a salted print was at worst a minor inconvenience when making a contact print by sunlight. Calotype negatives were often impregnated with wax to improve their transparency, Talbot is sometimes erroneously credited with introducing the principle of latent image development. Despite their flexibility and the ease with which they could be made, in part, this was the result of Talbot having patented his processes, unlike Daguerre who had been granted a stipend by the French state in exchange for making his process publicly available. In addition, the calotype produced a clear image than the daguerreotype. Albumen print Ambrotype Collodion process Daguerreotype Tintype Aronold, H. J. P. William Henry Fox Talbot pioneer of photography, the Calotype familiarly explained, Photography, including the Daguerreotype, Calotype & Chrysotype. Buckland, G. Fox Talbot & the invention of photography, primitive Photography, A Guide to Making Cameras, Lenses, and Calotypes Lassam, and Seabourne. W H Fox Talbot, Scientist, photographer, classical scholar 1800 -1877, marshall, F. A. S. Photography, the importance of its applications in preserving pictorial records. Containing a practical description of the Talbotype process, basic Photography — a manual for the training of fashion photographers
5.
Photogravure
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The earliest forms of photogravure were developed by two original pioneers of photography itself, first Nicéphore Niépce in France in the 1820s, and later Henry Fox Talbot in England. Niépce was seeking a means to create images on plates that could then be etched and used to make prints on paper with a traditional printing press. Niépces early images were among the first photographs, pre-dating daguerreotypes, Talbot, inventor of the calotype paper negative process, wanted to make paper prints that would not fade. He worked on his process in the 1850s and patented it in 1852 and 1858. Photogravure in its form was developed in 1878 by Czech painter Karel Klíč. This process, the one still in use today, is called the Talbot-Klič process, because of its high quality and richness, photogravure was used for both original fine art prints and for photo-reproduction of works from other media such as paintings. In France the correct term for photogravure is héliogravure, while the French term photogravure refers to any photo-based etching technique, Photogravure registers a wide variety of tones, through the transfer of etching ink from an etched copper plate to special dampened paper run through an etching press. The unique tonal range comes from photogravures variable depth of etch, that is, Photogravure practitioners such as Peter Henry Emerson and others brought the art to a high standard in the late 19th century. This continued with the work of Alfred Stieglitz in the early 20th century and this publication also featured the photogravures of Alvin Langdon Coburn who was a fine gravure printer and envisioned his photographic work as gravures rather than other photo-based processes. The speed and convenience of silver-gelatin photography eventually displaced photogravure which fell into disuse after the Edward S. Curtis gravures in the 1920s. One of the last major portfolios of fine art photogravures was Paul Strands Photographs from Mexico from 1940, many years later, photogravure has experienced a revival in the hands of Aperture and Jon Goodman, who studied it in Europe. Photogravure is now practiced in several dozen workshops around the world. Photogravure plates go through several stages, First, a continuous tone film positive is made from the original photographic negative. A smaller negative can be enlarged onto a sheet of film, the second stage is to sensitize a sheet of pigmented gelatin tissue by immersion into a 3. 5% solution of potassium dichromate for 3 minutes. Once dried against a Plexiglas surface, it is ready for the next stage, the third stage is to expose the film positive to the sensitized gravure tissue. The positive is placed on top of the sheet of pigmented gelatin tissue. The sandwich is then exposed to ultraviolet light, the UV light travels through the positive and screen in succession, each time hardening the gelatin in proportion to the degree of light exposed to it. The fourth stage is to adhere the exposed tissue to the copper plate, the gelatin tissue is adhered or laid down onto the highly polished copper plate under a layer of cool water
6.
The Pencil of Nature
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It was wholly executed by the new art of Photogenic Drawing, without any aid whatever from the artists pencil and regarded as an important and influential work in the history of photography. They are the sun-pictures themselves, and not, as some persons have imagined, the cover page for The Pencil of Nature clashed designs, which was characteristic of the Victorian era, with styles inspired by baroque, Celtic, and medieval elements. Its symmetrical design, letterforms, and intricate carpet pages are similar to, the Pencil of Nature was published and sold one section at a time, without any binding. Talbot planned a number of installments, however, the book was not a commercial success. The 24 plates in the book were selected to demonstrate the wide variety of uses to which photography could be put. They include a variety of studies, scenes, still-lifes, and closeups, as well as facsimiles of prints, sketches. Due to the exposure times involved, however, Talbot included only one portrait. Though he was no artist, Talbot also attempted to illustrate how photography could become a new form of art with images like The Open Door, the complete list of plates is as follows, Part 1 I. Part of Queens College, Oxford II, view of the Boulevards at Paris III. Bust of Patroclus Part 2 VI, fac-simile of an Old Printed Page X. Copy of a Lithographic Print XII, the Bridge of Orléans Part 3 XIII. Queens College, Oxford, Entrance Gateway XIV, Lacock Abbey in Wiltshire Part 4 XVI. Gate of Christchurch Part 5 XIX, the Tower of Lacock Abbey XX. The Martyrs Monument Part 6 XXII, a Fruit Piece Each plate is accompanied by a short text which describes the scene and the photographic processes involved in obtaining it. He also speculated about such questions as whether photographs would stand up as evidence in court, at the beginning of the book, Talbot included an incomplete history of his development of the calotype, titled Brief Historical Sketch of the Invention of the Art. The history ends rather abruptly, and though Talbot expressed his intention to complete it at a later date, only about 15 complete copies of the original 1844-1846 edition still exist. At least two editions have been issued, New York, Da Capo Press,1969. New York, Hans P. Kraus, Jr.1989, ISBN 0-9621096-0-6 Bath, Monmouth Calotype 1989 The Pencil of Nature at Project Gutenberg
7.
Negative (photography)
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In the case of color negatives, the colors are also reversed into their respective complementary colors. Typical color negatives have a dull orange tint due to an automatic color-masking feature that ultimately results in improved color reproduction. Negatives are normally used to make prints on photographic paper by projecting the negative onto the paper with a photographic enlarger or making a contact print. The paper is also darkened in proportion to its exposure to light, so a second reversal results which restores light, negatives were once commonly made on a thin sheet of glass rather than a plastic film, and some of the earliest negatives were made on paper. It is incorrect to call an image a negative solely because it is on a transparent material, transparent prints can be made by printing a negative onto special positive film, as is done to make traditional motion picture film prints for use in theaters. Some films used in cameras are designed to be developed by reversal processing, positives on film or glass are known as transparencies or diapositives, and if mounted in small frames designed for use in a slide projector or magnifying viewer they are commonly called slides. A positive image is a normal image, a negative image is a total inversion, in which light areas appear dark and vice versa. A negative color image is additionally color-reversed, with red areas appearing cyan, greens appearing magenta and blues appearing yellow, film negatives usually have less contrast, but a wider dynamic range, than the final printed positive images. The contrast typically increases when they are printed onto photographic paper, when negative film images are brought into the digital realm, their contrast may be adjusted at the time of scanning or, more usually, during subsequent post-processing. Film for cameras that use the 35 mm still format is sold as a strip of emulsion-coated and perforated plastic spooled in a light-tight cassette. Before each exposure, a mechanism inside the camera is used to pull an unexposed area of the out of the cassette. When all exposures have been made the strip is rewound into the cassette, after the film is chemically developed, the strip shows a series of small negative images. It is usually cut into sections for easier handling. Each of these images may be referred to as a negative. They are the images, from which all positive prints will derive. However, when an image is created from a negative image a positive image results. This makes most chemical-based photography a two-step process, which uses negative film, special films and development processes have been devised so that positive images can be created directly on the film, these are called positive, or slide, or reversal films and reversal processing. Scanning film negatives at the Wayback Machine NegaTIV -. -
8.
Polymath
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A polymath is a person whose expertise spans a significant number of different subject areas, such a person is known to draw on complex bodies of knowledge to solve specific problems. The term was first used in the 17th century, the related term, the term is often used to describe great thinkers of the Renaissance and the Enlightenment who excelled at several fields in science and the arts. In the Italian Renaissance, the idea of the polymath was expressed by Leon Battista Alberti and this term entered the lexicon during the twentieth century and has now been applied to great thinkers living before and after the Renaissance. Renaissance man was first recorded in written English in the early 20th century and it is now used to refer to great thinkers living before, during, or after the Renaissance. Leonardo da Vinci has often described as the archetype of the Renaissance man. These polymaths had an approach to education that reflected the ideals of the humanists of the time. A gentleman or courtier of that era was expected to speak several languages, play an instrument, write poetry. The idea of an education was essential to achieving polymath ability. At this time, universities did not specialize in specific areas but rather trained students in an array of science, philosophy. This universal education gave them a grounding from which they could continue into apprenticeship toward becoming a master of a specific field, aside from Renaissance man as mentioned above, similar terms in use are Homo Universalis and Uomo Universale, which translate to universal person or universal man. The related term generalist—contrasted with a used to describe a person with a general approach to knowledge. The term Universal Genius or Versatile Genius is also used, with Leonardo da Vinci as the prime example again. The term seems to be used especially when a person has made lasting contributions in at least one of the fields in which he was involved. When a person is described as having knowledge, they exhibit a vast scope of knowledge. This designation may be anachronistic, however, in the case of such as Eratosthenes whose reputation for having encyclopedic knowledge predates the existence of any encyclopedic object. One whose accomplishments are limited to athletics would not be considered a polymath in the sense of the word. An example is Howard Baker, who was called a sporting polymath by the Encyclopedia of British Football for winning high jump titles and playing cricket, football, many polymaths from across the centuries have their roots in medical applications. One of the well known polymaths, Leonardo da Vinci, was known for his immense interest in human anatomical structure
9.
Royal Society
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Founded in November 1660, it was granted a royal charter by King Charles II as The Royal Society. The society is governed by its Council, which is chaired by the Societys President, according to a set of statutes and standing orders. The members of Council and the President are elected from and by its Fellows, the members of the society. As of 2016, there are about 1,600 fellows, allowed to use the postnominal title FRS, there are also royal fellows, honorary fellows and foreign members, the last of which are allowed to use the postnominal title ForMemRS. The Royal Society President is Venkatraman Ramakrishnan, who took up the post on 30 November 2015, since 1967, the society has been based at 6–9 Carlton House Terrace, a Grade I listed building in central London which was previously used by the Embassy of Germany, London. The Royal Society started from groups of physicians and natural philosophers, meeting at variety of locations and they were influenced by the new science, as promoted by Francis Bacon in his New Atlantis, from approximately 1645 onwards. A group known as The Philosophical Society of Oxford was run under a set of rules still retained by the Bodleian Library, after the English Restoration, there were regular meetings at Gresham College. It is widely held that these groups were the inspiration for the foundation of the Royal Society, I will not say, that Mr Oldenburg did rather inspire the French to follow the English, or, at least, did help them, and hinder us. But tis well known who were the men that began and promoted that design. This initial royal favour has continued and, since then, every monarch has been the patron of the society, the societys early meetings included experiments performed first by Hooke and then by Denis Papin, who was appointed in 1684. These experiments varied in their area, and were both important in some cases and trivial in others. The Society returned to Gresham in 1673, there had been an attempt in 1667 to establish a permanent college for the society. Michael Hunter argues that this was influenced by Solomons House in Bacons New Atlantis and, to a lesser extent, by J. V. The first proposal was given by John Evelyn to Robert Boyle in a letter dated 3 September 1659, he suggested a scheme, with apartments for members. The societys ideas were simpler and only included residences for a handful of staff and these plans were progressing by November 1667, but never came to anything, given the lack of contributions from members and the unrealised—perhaps unrealistic—aspirations of the society. During the 18th century, the gusto that had characterised the early years of the society faded, with a number of scientific greats compared to other periods. The pointed lightning conductor had been invented by Benjamin Franklin in 1749, during the same time period, it became customary to appoint society fellows to serve on government committees where science was concerned, something that still continues. The 18th century featured remedies to many of the early problems
10.
Integral
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In mathematics, an integral assigns numbers to functions in a way that can describe displacement, area, volume, and other concepts that arise by combining infinitesimal data. Integration is one of the two operations of calculus, with its inverse, differentiation, being the other. The area above the x-axis adds to the total and that below the x-axis subtracts from the total, roughly speaking, the operation of integration is the reverse of differentiation. For this reason, the integral may also refer to the related notion of the antiderivative. In this case, it is called an integral and is written. The integrals discussed in this article are those termed definite integrals, a rigorous mathematical definition of the integral was given by Bernhard Riemann. It is based on a procedure which approximates the area of a curvilinear region by breaking the region into thin vertical slabs. A line integral is defined for functions of two or three variables, and the interval of integration is replaced by a curve connecting two points on the plane or in the space. In a surface integral, the curve is replaced by a piece of a surface in the three-dimensional space and this method was further developed and employed by Archimedes in the 3rd century BC and used to calculate areas for parabolas and an approximation to the area of a circle. A similar method was developed in China around the 3rd century AD by Liu Hui. This method was used in the 5th century by Chinese father-and-son mathematicians Zu Chongzhi. The next significant advances in integral calculus did not begin to appear until the 17th century, further steps were made in the early 17th century by Barrow and Torricelli, who provided the first hints of a connection between integration and differentiation. Barrow provided the first proof of the theorem of calculus. Wallis generalized Cavalieris method, computing integrals of x to a power, including negative powers. The major advance in integration came in the 17th century with the independent discovery of the theorem of calculus by Newton. The theorem demonstrates a connection between integration and differentiation and this connection, combined with the comparative ease of differentiation, can be exploited to calculate integrals. In particular, the theorem of calculus allows one to solve a much broader class of problems. Equal in importance is the mathematical framework that both Newton and Leibniz developed
11.
Optics
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Optics is the branch of physics which involves the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviolet, and infrared light, because light is an electromagnetic wave, other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves exhibit similar properties. Most optical phenomena can be accounted for using the classical description of light. Complete electromagnetic descriptions of light are, however, often difficult to apply in practice, practical optics is usually done using simplified models. The most common of these, geometric optics, treats light as a collection of rays that travel in straight lines, physical optics is a more comprehensive model of light, which includes wave effects such as diffraction and interference that cannot be accounted for in geometric optics. Historically, the model of light was developed first, followed by the wave model of light. Progress in electromagnetic theory in the 19th century led to the discovery that waves were in fact electromagnetic radiation. Some phenomena depend on the fact that light has both wave-like and particle-like properties, explanation of these effects requires quantum mechanics. When considering lights particle-like properties, the light is modelled as a collection of particles called photons, quantum optics deals with the application of quantum mechanics to optical systems. Optical science is relevant to and studied in many related disciplines including astronomy, various engineering fields, photography, practical applications of optics are found in a variety of technologies and everyday objects, including mirrors, lenses, telescopes, microscopes, lasers, and fibre optics. Optics began with the development of lenses by the ancient Egyptians and Mesopotamians, the earliest known lenses, made from polished crystal, often quartz, date from as early as 700 BC for Assyrian lenses such as the Layard/Nimrud lens. The ancient Romans and Greeks filled glass spheres with water to make lenses, the word optics comes from the ancient Greek word ὀπτική, meaning appearance, look. Greek philosophy on optics broke down into two opposing theories on how vision worked, the theory and the emission theory. The intro-mission approach saw vision as coming from objects casting off copies of themselves that were captured by the eye, plato first articulated the emission theory, the idea that visual perception is accomplished by rays emitted by the eyes. He also commented on the parity reversal of mirrors in Timaeus, some hundred years later, Euclid wrote a treatise entitled Optics where he linked vision to geometry, creating geometrical optics. Ptolemy, in his treatise Optics, held a theory of vision, the rays from the eye formed a cone, the vertex being within the eye. The rays were sensitive, and conveyed back to the observer’s intellect about the distance. He summarised much of Euclid and went on to describe a way to measure the angle of refraction, during the Middle Ages, Greek ideas about optics were resurrected and extended by writers in the Muslim world
12.
Chemistry
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Chemistry is a branch of physical science that studies the composition, structure, properties and change of matter. Chemistry is sometimes called the science because it bridges other natural sciences, including physics. For the differences between chemistry and physics see comparison of chemistry and physics, the history of chemistry can be traced to alchemy, which had been practiced for several millennia in various parts of the world. The word chemistry comes from alchemy, which referred to a set of practices that encompassed elements of chemistry, metallurgy, philosophy, astrology, astronomy, mysticism. An alchemist was called a chemist in popular speech, and later the suffix -ry was added to this to describe the art of the chemist as chemistry, the modern word alchemy in turn is derived from the Arabic word al-kīmīā. In origin, the term is borrowed from the Greek χημία or χημεία and this may have Egyptian origins since al-kīmīā is derived from the Greek χημία, which is in turn derived from the word Chemi or Kimi, which is the ancient name of Egypt in Egyptian. Alternately, al-kīmīā may derive from χημεία, meaning cast together, in retrospect, the definition of chemistry has changed over time, as new discoveries and theories add to the functionality of the science. The term chymistry, in the view of noted scientist Robert Boyle in 1661, in 1837, Jean-Baptiste Dumas considered the word chemistry to refer to the science concerned with the laws and effects of molecular forces. More recently, in 1998, Professor Raymond Chang broadened the definition of chemistry to mean the study of matter, early civilizations, such as the Egyptians Babylonians, Indians amassed practical knowledge concerning the arts of metallurgy, pottery and dyes, but didnt develop a systematic theory. Greek atomism dates back to 440 BC, arising in works by such as Democritus and Epicurus. In 50 BC, the Roman philosopher Lucretius expanded upon the theory in his book De rerum natura, unlike modern concepts of science, Greek atomism was purely philosophical in nature, with little concern for empirical observations and no concern for chemical experiments. Work, particularly the development of distillation, continued in the early Byzantine period with the most famous practitioner being the 4th century Greek-Egyptian Zosimos of Panopolis. He formulated Boyles law, rejected the four elements and proposed a mechanistic alternative of atoms. Before his work, though, many important discoveries had been made, the Scottish chemist Joseph Black and the Dutchman J. B. English scientist John Dalton proposed the theory of atoms, that all substances are composed of indivisible atoms of matter. Davy discovered nine new elements including the alkali metals by extracting them from their oxides with electric current, british William Prout first proposed ordering all the elements by their atomic weight as all atoms had a weight that was an exact multiple of the atomic weight of hydrogen. The inert gases, later called the noble gases were discovered by William Ramsay in collaboration with Lord Rayleigh at the end of the century, thereby filling in the basic structure of the table. Organic chemistry was developed by Justus von Liebig and others, following Friedrich Wöhlers synthesis of urea which proved that organisms were, in theory
13.
Electricity
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Electricity is the set of physical phenomena associated with the presence of electric charge. Although initially considered a separate to magnetism, since the development of Maxwells Equations both are recognized as part of a single phenomenon, electromagnetism. Various common phenomena are related to electricity, including lightning, static electricity, electric heating, electric discharges, in addition, electricity is at the heart of many modern technologies. The presence of a charge, which can be either positive or negative. On the other hand, the movement of charges, which is known as electric current. When a charge is placed in a location with non-zero electric field, the magnitude of this force is given by Coulombs Law. Thus, if that charge were to move, the field would be doing work on the electric charge. Electrical phenomena have been studied since antiquity, though progress in theoretical understanding remained slow until the seventeenth and eighteenth centuries. Even then, practical applications for electricity were few, and it would not be until the nineteenth century that engineers were able to put it to industrial and residential use. The rapid expansion in electrical technology at this time transformed industry, electricitys extraordinary versatility means it can be put to an almost limitless set of applications which include transport, heating, lighting, communications, and computation. Electrical power is now the backbone of modern industrial society, long before any knowledge of electricity existed, people were aware of shocks from electric fish. Ancient Egyptian texts dating from 2750 BCE referred to these fish as the Thunderer of the Nile, Electric fish were again reported millennia later by ancient Greek, Roman and Arabic naturalists and physicians. Patients suffering from such as gout or headache were directed to touch electric fish in the hope that the powerful jolt might cure them. Ancient cultures around the Mediterranean knew that certain objects, such as rods of amber, Thales was incorrect in believing the attraction was due to a magnetic effect, but later science would prove a link between magnetism and electricity. He coined the New Latin word electricus to refer to the property of attracting small objects after being rubbed and this association gave rise to the English words electric and electricity, which made their first appearance in print in Thomas Brownes Pseudodoxia Epidemica of 1646. Further work was conducted by Otto von Guericke, Robert Boyle, Stephen Gray, in the 18th century, Benjamin Franklin conducted extensive research in electricity, selling his possessions to fund his work. In June 1752 he is reputed to have attached a key to the bottom of a dampened kite string. A succession of jumping from the key to the back of his hand showed that lightning was indeed electrical in nature
14.
Ancient history
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Ancient history is the aggregate of past events from the beginning of recorded human history and extending as far as the Early Middle Ages or the Postclassical Era. The span of recorded history is roughly 5,000 years, beginning with Sumerian Cuneiform script, the term classical antiquity is often used to refer to history in the Old World from the beginning of recorded Greek history in 776 BC. This roughly coincides with the date of the founding of Rome in 753 BC, the beginning of the history of ancient Rome. In India, ancient history includes the period of the Middle Kingdoms, and, in China. Historians have two major avenues which they take to better understand the ancient world, archaeology and the study of source texts, primary sources are those sources closest to the origin of the information or idea under study. Primary sources have been distinguished from secondary sources, which cite, comment on. Archaeology is the excavation and study of artefacts in an effort to interpret, archaeologists excavate the ruins of ancient cities looking for clues as to how the people of the time period lived. The study of the ancient cities of Harappa, Mohenjo-daro, the city of Pompeii, an ancient Roman city preserved by the eruption of a volcano in AD79. Its state of preservation is so great that it is a window into Roman culture and provided insight into the cultures of the Etruscans. The Terracotta Army, the mausoleum of the First Qin Emperor in ancient China, the discovery of Knossos by Minos Kalokairinos and Sir Arthur Evans. The discovery of Troy by Heinrich Schliemann, most of what is known of the ancient world comes from the accounts of antiquitys own historians. Although it is important to take account the bias of each ancient author. Some of the more notable ancient writers include Herodotus, Thucydides, Arrian, Plutarch, Polybius, Sima Qian, Sallust, Livy, Josephus, Suetonius, furthermore, the reliability of the information obtained from these surviving records must be considered. Few people were capable of writing histories, as literacy was not widespread in almost any culture until long after the end of ancient history, the earliest known systematic historical thought emerged in ancient Greece, beginning with Herodotus of Halicarnassus. He was also the first to distinguish between cause and immediate origins of an event, the Roman Empire was one of the ancient worlds most literate cultures, but many works by its most widely read historians are lost. Indeed, only a minority of the work of any major Roman historian has survived, prehistory is the period before written history. The early human migrations in the Lower Paleolithic saw Homo erectus spread across Eurasia 1.8 million years ago, the controlled use of fire occurred 800,000 years ago in the Middle Paleolithic. 250,000 years ago, Homo sapiens emerged in Africa, 60–70,000 years ago, Homo sapiens migrated out of Africa along a coastal route to South and Southeast Asia and reached Australia
15.
Lacock Abbey
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Lacock Abbey in the village of Lacock, Wiltshire, England, was founded in the early 13th century by Ela, Countess of Salisbury, as a nunnery of the Augustinian order. The abbey remained a nunnery until the suppression of Catholic institutions in England in the 16th century and it was then sold to Sir William Sharington who converted the convent into a residence where he and his family lived. It was fortified and remained loyal to the crown during the English Civil War, the house was built over the old cloisters and the main rooms are on the first floor. It is a house with stone slated roofs, twisted chimney stacks. Throughout the life of the building, many alterations, additions. The Tudor stable courtyard to the north of the house has retained many of its original features including the old brewhouse and bakehouse, the house later passed into the hands of the Talbot family and during the 19th century, served as the residence for William Henry Fox Talbot. In 1835 he made what may be the earliest surviving photographic camera negative, the house and the surrounding village of Lacock were given to the National Trust in 1944. The abbey houses the Fox Talbot Museum, devoted to the work of William Talbots work in the field of photography. The Trust markets the abbey and village together as Lacock Abbey, the abbey is a Grade I listed building, having been so designated on 20 December 1960. Her late husband had been William Longespee, an son of King Henry II. The abbey was founded in Snails Meadow, near the village of Lacock, the first of the Augustinian nuns were veiled in 1232. Generally, Lacock Abbey prospered throughout the Middle Ages, the rich farmlands which it had received from Ela ensured it a sizeable income from wool. So as not to be incommoded by villagers passing close to his residence, he is said to have sold the church bells, few other alterations were made to the monastic buildings themselves, the cloisters, for example, still stand below the living accommodation. In each chamber is an octagonal stone table, carved with up-to-date Renaissance ornament. A mid-16th century stone conduit house stands over the spring from which water was conducted to the house, further additions were made over the centuries, and the house now has various grand reception rooms. In the 16th and early 17th centuries, Nicholas Cooper has pointed out, during the English Civil War the house was garrisoned by Royalists. It was fortified by surrounding it with earthworks, the house eventually passed to the Talbot family. Talbots experiments eventually led to his invention of the sensitive and practical calotype or Talbotype paper negative process for camera use
16.
Chippenham
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Chippenham is an historic market town in Wiltshire, England,13 miles east of Bath and 96 miles west of London. It was a vill, and probably a royal hunting lodge. The primary school, Kings Lodge School, gets its name from this tradition, the town continued to grow when the Great Western Railway arrived in 1841. The town is now a commuter town, Chippenham is twinned with La Flèche in France and Friedberg in Germany. The towns motto is Unity and Loyalty, the town is surrounded by sparsely populated countryside and there are several woodlands in or very near the town, such as Birds Marsh, Vincients Wood and Briars Wood. Chippenham lies 4 miles south of the M4 motorway, which links the town to Bristol, Swindon, South Wales, the A4 former coach road, A420 and B4069 provide further road links to Bath, Bristol and Oxford. The town is bypassed to the west by the A350, which links the M4 motorway with Chippenham and nearby towns to the south, such as Melksham, Warminster and Trowbridge. The A4 national route crosses the southern part of the town, linking Chippenham to nearby Corsham, Calne, local councillors have called for an eastern extension linking the A4 to the A350 north of Cepen Park although this has been opposed by many residents. Dualling work on a 2-mile /3 km stretch of the A350 eastern bypass commenced in January 2015 from Cepen Park North through to the A4, which is scheduled for completion in 2017. Two shorter single carriageway sections of the A350 from just south of the Plough crossroads to Cepen Park North were both converted to dual carriageway between October 2014 and March 2015, Chippenham has a bus station with several routes and companies serving it. APLtravel with the 33 to Devizes and it is served by main line services and a smaller service to Southampton Central via Melksham, Westbury and Salisbury. It is being electrified to make train times faster from London to the West Country, National Express Coach services connect at Chippenham to London, Wales, South West England, the Midlands and East Anglia. Bus services connect the town to Bristol, Bath, Corsham, Calne, Frome, Devizes, Trowbridge, Swindon and nearby villages. The original Buttercross, a structure, was erected in c.1570 and stood at the centre of the Shambles. It was used for the sale of meat and dairy products, in 1889, Mr E. C. Lowndes bought the Buttercross for £6 and re-erected it as a gazebo in the kitchen garden of the Castle Combe Manor House, where it subsequently fell into disrepair. The Buttercross was re-erected in 1995 by the Chippenham Civic Society, funded by local people. It currently stands as the centre-piece of the area of the town centre. The Yelde Hall is one of few remaining medieval timber framed buildings in the town
17.
Rottingdean
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Rottingdean is a coastal village next to the town of Brighton and within the city of Brighton and Hove, in East Sussex, on the south coast of England. It borders the villages of Saltdean, Ovingdean and Woodingdean, and has a historic centre, the name is Old English for valley of the people associated with Rōta. Rota was probably the leader of a band of warlike Saxons who invaded the region in 450–500 AD, the first recorded mention is in the Domesday Book. Other variations to be found in ancient charters include Ruttingedene, Rottyngden, Rottingdean is in a dry valley whose sides in the upper reaches are quite steep, and this valley comes right down to the English Channel coast. The name was contrasted unflatteringly with Goodwood in a national 1970s advertising campaign for wood preserver, some, in the late 19th century, notably the painter Sir Edward Burne-Jones and his nephew Rudyard Kipling, made it their home. Kiplings old house adjacent to Kipling Gardens is still standing, when farming collapsed in the 1920s, much of the farmland became available for building, and Rottingdean increased significantly in population, but especially in the area known as Saltdean. A large number of smallholdings appeared in the part of the parish called Woodingdean. In the summer of 1377 French pirates raided Rottingdean, the raiders probably intended to pillage the nearby Lewes priory. The raiders were detected as they landed, and a portion of the inhabitants retreated into the churchs Saxon-built tower. The pirates were unable to take the tower and set it on fire, the next day the pirates were met by a force led by the Lewes Prior. During the action, two knights, Sir John Fallisle, Thomas Chinie and the prior were captured, the pirates were, however, driven to depart, with the three men later being ransomed. Rottingdean is also notable for the wooden windmill on the hill on its western side. The Rottingdean Preservation Society and its earlier incarnations have been responsible for maintaining the windmill since 1923, the hill is a local nature reserve. It was also known for sport, having a cricket club founded in 1758 and having been a centre of fox hunting. The shop, the Old Customs House, was the inspiration for the shop in The League of Gentlemen. Its most historic building is its probably 13th-century church of St Margaret, built of flint. An almost exact replica has been built at the Forest Lawn Memorial Park, Glendale, the Rottingdean church features stained glass by Edward Burne-Jones, whose ashes are buried in the churchyard. Here is also the grave of the last squire of Rottingdean, Steyning Beard, the famous blues guitarist Gary Moore is buried at the church after his death in February 2011
18.
Harrow School
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Harrow School /ˈhæroʊ/ is an independent boarding school for boys in Harrow, London, England. There is some evidence that there has been a school on the site since 1243, Harrow is one of the original nine public schools that were regulated by the Public Schools Act 1868. For the academic year 2016/17, Harrow charges boarders up to £12,450 per term, being the fourth most expensive boarding school in the Headmasters, the school has an enrolment of 805 boys spread across twelve boarding houses, all of whom board full-time. It remains one of four all-boys, full-boarding schools in Britain, harrows uniform includes straw hats, morning suits, top hats and canes. The school in its current form was founded in February 1572 under a Royal Charter granted by Queen Elizabeth I to John Lyon, a wealthy local farmer. In the original charter, six governors were named, including two members of the Gerard family of Flambards, and two members of the Page family of Wembley and Sudbury Court. It was only after the death of Lyons wife in 1608 that the construction of the first school building began and it was completed in 1615 and remains to this day, however it is now much larger. Lyon died in 1592, leaving his assets to two causes, the lesser was the School, and by far the greater beneficiary was the maintenance of a road to London,10 miles away. The school owned and maintained road for many years following Lyons death. At first the subject taught was Latin, and the only sport was archery. Both subjects were compulsory, archery was dropped in 1771, although most boys were taught for free, their tuition paid for by Lyons endowment, there were a number of fee-paying foreigners. It was their presence that amplified the need for boarding facilities, by 1701 for every local there were two foreign pupils, these generated funds for the School as fees increased. It is now known as The John Lyon School and is a prominent independent school and it maintains close links with Harrow. The majority of the boarding houses were constructed in Victorian times. The 20th century saw the innovation of a dining hall. Presently there are about 800 boys boarding at Harrow, according to a 2009 article, the school has expanded overseas, opening additional schools in Beijing, China, Shanghai, China, Bangkok, Thailand, and New Territories, Hong Kong. Boys at Harrow have two uniforms, the photograph was placed on the front cover of the News Chronicle the next morning under the tagline Every picture tells a story. The picture was reproduced in other national publications and became
19.
Trinity College, Cambridge
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Trinity College is a constituent college of the University of Cambridge in England. With around 600 undergraduates,300 graduates, and over 180 fellows, by combined student numbers, it is second to Homerton College, Cambridge. Members of Trinity have won 32 Nobel Prizes out of the 91 won by members of Cambridge University, five Fields Medals in mathematics were won by members of the college and one Abel Prize was won. Other royal family members have studied there without obtaining degrees, including King Edward VII, King George VI, along with Christs, Jesus, Kings and St Johns colleges, it has also provided several of the well known members of the Apostles, an intellectual secret society. In 1848, Trinity hosted the meeting at which Cambridge undergraduates representing private schools such as Westminster drew up the first formal rules of football, Trinitys sister college in Oxford is Christ Church. Like that college, Trinity has been linked with Westminster School since the schools re-foundation in 1560, the college was founded by Henry VIII in 1546, from the merger of two existing colleges, Michaelhouse, and Kings Hall. At the time, Henry had been seizing church lands from abbeys, the universities of Oxford and Cambridge, being both religious institutions and quite rich, expected to be next in line. The King duly passed an Act of Parliament that allowed him to any college he wished. The universities used their contacts to plead with his sixth wife, the Queen persuaded her husband not to close them down, but to create a new college. The king did not want to use royal funds, so he combined two colleges and seven hostels to form Trinity. Contrary to popular belief, the lands granted by Henry VIII were not on their own sufficient to ensure Trinitys eventual rise. In its infancy Trinity had owed a great deal to its college of St Johns. Its first four Masters were educated at St Johns, and it took until around 1575 for the two colleges application numbers to draw even, a position in which they have remained since the Civil War. Bentley himself was notorious for the construction of a hugely expensive staircase in the Masters Lodge, most of the Trinitys major buildings date from the 16th and 17th centuries. Thomas Nevile, who became Master of Trinity in 1593, rebuilt and this work included the enlargement and completion of Great Court, and the construction of Neviles Court between Great Court and the river Cam. Neviles Court was completed in the late 17th century when the Wren Library, in the 20th century, Trinity College, St Johns College and Kings College were for decades the main recruiting grounds for the Cambridge Apostles, an elite, intellectual secret society. In 2011, the John Templeton Foundation awarded Trinity Colleges Master, Trinity is the richest Oxbridge college, with a landholding alone worth £800 million. Trinity is sometimes suggested to be the second, third or fourth wealthiest landowner in the UK – after the Crown Estate, the National Trust, in 2005, Trinitys annual rental income from its properties was reported to be in excess of £20 million
20.
Wrangler (University of Cambridge)
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At the University of Cambridge in England, a Wrangler is a student who gains first-class honours in the third year of the Universitys undergraduate degree in mathematics. The highest-scoring student is the Senior Wrangler, the second highest is the Second Wrangler, at the other end of the scale, the person who achieves the lowest exam marks while still earning a third-class honours degree is known as the wooden spoon. Until 1909, the University made the rankings public, since 1910 it has publicly revealed only the class of degree gained by each student. An examiner reveals the identity of the Senior Wrangler unofficially by tipping his hat when reading out the persons name, therefore, the names of only some 20th-century Senior Wranglers have become publicly known. She was educated at Newnham College, Cambridge which had been co-founded by her mother, in 1890, Fawcett became the first woman to obtain the top score in the Cambridge Mathematical Tripos exams. Her score was 13 per cent higher than the second highest score, the results were always highly publicised, with the top scorers receiving great acclaim. Women had been allowed to take the Tripos since 1881, after Charlotte Angas Scott was unofficially ranked as eighth wrangler, the strain of preparing for Tripos could lead to mental breakdown. Students found it necessary to build up their physical endurance and it was noted that virtually every high wrangler participated in some form of regular physical exercise to preserve his strength and stamina. Obtaining the position of a highly ranked Wrangler created many opportunities for the individuals subsequent profession and they would often become Fellows initially, before moving on to other professions, such as law, the Church, or medicine. Throughout the United Kingdom and the British Empire, university professors were often among the top three Wranglers. The order of Wranglers was widely publicised and shaped the perception of mathematics as being the most intellectually challenging of all subjects. According to Andrew Warwick, author of Masters of Theory, the term Senior Wrangler became synonymous with academic supremacy. Bragg was third, Hardy was fourth, Sedgwick fifth, Malthus was ninth, Bertrand Russell was seventh, Keynes was 12th and that policy was abandoned in 1948. Students who achieve second-class and third-class mathematics degrees are known as Senior Optimes, Cambridge did not divide its examination classification in mathematics into 2, 1s and 2, 2s until 1995 but now there are Senior Optimes Division 1 and Senior Optimes Division 2. The Senior Wrangler is a member of the faculty of Unseen University in Terry Pratchetts Discworld series of novels, roger Hamley, a character in Elizabeth Gaskells Wives and Daughters, achieved the rank of Senior Wrangler at Cambridge. Vivie Warren, the heroine of George Bernard Shaws Mrs. Wrangler is a jargon term applied to codebreakers in some of John Le Carrés spy novels. Thomas Jericho, the character of Robert Harriss book Enigma, was Senior Wrangler in 1938. In Ford Madox Fords Parades End, reference is made to the fact that Christopher Tietjens came out of Cambridge as a mere Second Wrangler, in Rumer Goddens In This House of Brede, Dame Agnes is noted to have been Eighth Wrangler before entering the abbey
21.
Royal Society of Edinburgh
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The Royal Society of Edinburgh is Scotlands national academy of science and letters. It is a charity, operating on a wholly independent and non-party-political basis. As of 2014 it has more than 1,500 Fellows, the Society covers a broader selection of fields than the Royal Society of London including literature and history. Fellowship includes people from a range of disciplines – science & technology, arts, humanities, medicine, social science, business. The Medals were instituted in 2000 by Queen Elizabeth II, whose permission is required to make a presentation, past winners include, The Lord Kelvin Medal is the Senior Prize for Physical, Engineering and Informatics Sciences. It is awarded annually to a person who has achieved distinction nationally and internationally, winners receive a silver medal and are required to deliver a public lecture in Scotland. The award is named after William Thomson, 1st Baron Kelvin, who was a mathematical physicist and engineer. Senior Prize-winners are required to have a Scottish connection but can be based anywhere in the world, the Keith medal has been historically awarded every four years for a scientific paper published in the societys scientific journals, preference being given to a paper containing a discovery. It is awarded alternately for papers on Mathematics or Earth and Environmental Sciences, the medal was founded in 1827 as a result of a bequest by Alexander Keith of Dunottar, the first Treasurer of the Society. The prize was founded in 1855 by Sir Thomas Makdougall Brisbane, the cumbersome name was changed the following year to the Edinburgh Philosophical Society. Under the leadership of Prof. Thus, for the first four decades of the 19th century, by the 1850s, the society once again unified its membership under one journal. During the 19th century the society produced many scientists whose ideas laid the foundation of the modern sciences, from the 20th century onward, the society functioned not only as a focal point for Scotlands eminent scientists, but also the arts and humanities. It still exists today and continues to promote research in Scotland. In February 2014, Dame Jocelyn Bell Burnell was announced as the societys first female president, taking up her position in October
22.
Philosophical Magazine
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The Philosophical Magazine is one of the oldest scientific journals published in English. It was established by Alexander Tilloch in 1798, in 1822 Richard Taylor became joint editor, the name of the journal dates from a period when natural philosophy embraced all aspects of science. The very first paper published in the journal carried the title Account of Mr Cartwrights Patent Steam Engine. In 1814, the Philosophical Magazine merged with the Journal of Natural Philosophy, Chemistry, in 1949, the title reverted to The Philosophical Magazine. In the early part of the 20th century, Ernest Rutherford was a frequent contributor and he once told a friend to watch out for the next issue of Philosophical Magazine, it is highly radioactive. Another classic contribution from Rutherford was entitled Collision of α Particles with Light Atoms, an Anomalous Effect in Nitrogen – an article describing no less than the first artificial transmutation of an element. In 1978 the journal was divided into two independent parts, Philosophical Magazine A and Philosophical Magazine B, Part A published papers on structure, defects and mechanical properties while Part B focussed on statistical mechanics, electronic, optical and magnetic properties. In its current form,36 issues of the Philosophical Magazine are published each year, previous editors of the Philosophical Magazine have been John Tyndall, J. J. Thomson, Sir Nevill Mott, and William Lawrence Bragg, the journal is currently edited by Edward A. Davis. In 1987, the sister journal Philosophical Magazine Letters was established with the aim of publishing short communications on all aspects of condensed matter physics. It is edited by Edward A. Davis and Peter Riseborough and this monthly journal had a 2014 impact factor of 1.087. Over its 200-year history, Philosophical Magazine has occasionally restarted its volume numbers at 1, designating a new series each time
23.
Photography
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Typically, a lens is used to focus the light reflected or emitted from objects into a real image on the light-sensitive surface inside a camera during a timed exposure. With an electronic sensor, this produces an electrical charge at each pixel. A negative image on film is used to photographically create a positive image on a paper base, known as a print. The word photography was created from the Greek roots φωτός, genitive of φῶς, light and γραφή representation by means of lines or drawing, several people may have coined the same new term from these roots independently. Johann von Maedler, a Berlin astronomer, is credited in a 1932 German history of photography as having used it in an article published on 25 February 1839 in the German newspaper Vossische Zeitung. Both of these claims are now widely reported but apparently neither has ever been confirmed as beyond reasonable doubt. Credit has traditionally given to Sir John Herschel both for coining the word and for introducing it to the public. Photography is the result of combining several technical discoveries, later Greek mathematicians Aristotle and Euclid also independently described a pinhole camera in the 5th and 4th centuries BCE. Daniele Barbaro described a diaphragm in 1566, wilhelm Homberg described how light darkened some chemicals in 1694. The fiction book Giphantie, published in 1760, by French author Tiphaigne de la Roche, the discovery of the camera obscura that provides an image of a scene dates back to ancient China. Leonardo da Vinci mentions natural camera obscura that are formed by dark caves on the edge of a sunlit valley, a hole in the cave wall will act as a pinhole camera and project a laterally reversed, upside down image on a piece of paper. So the birth of photography was primarily concerned with inventing means to capture, renaissance painters used the camera obscura which, in fact, gives the optical rendering in color that dominates Western Art. The camera obscura literally means dark chamber in Latin and it is a box with a hole in it which allows light to go through and create an image onto the piece of paper. Around the year 1800, British inventor Thomas Wedgwood made the first known attempt to capture the image in a camera obscura by means of a light-sensitive substance and he used paper or white leather treated with silver nitrate. The shadow images eventually darkened all over, the first permanent photoetching was an image produced in 1822 by the French inventor Nicéphore Niépce, but it was destroyed in a later attempt to make prints from it. Niépce was successful again in 1825, in 1826 or 1827, he made the View from the Window at Le Gras, the earliest surviving photograph from nature. Because Niépces camera photographs required a long exposure, he sought to greatly improve his bitumen process or replace it with one that was more practical. With an eye to eventual commercial exploitation, the partners opted for total secrecy, Daguerres efforts culminated in what would later be named the daguerreotype process
24.
View from the Window at Le Gras
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View from the Window at Le Gras is a heliographic image and the oldest surviving camera photograph. It was created by Nicéphore Niépce in 1826 or 1827 at Saint-Loup-de-Varennes, France, Niépce captured the scene with a camera obscura focused onto a 16.2 cm ×20.2 cm pewter plate thinly coated with Bitumen of Judea, a naturally occurring asphalt. The bitumen hardened in the brightly lit areas, but in the dimly lit areas it remained soluble and could be washed away with a mixture of oil of lavender, a very long exposure in the camera was required. Sunlight strikes the buildings on opposite sides, suggesting an exposure that lasted eight hours. A researcher who studied Niépces notes and recreated his processes found that the exposure must have continued for several days, in late 1827, Niépce visited England. He showed this and several specimens of his work to botanical illustrator Francis Bauer. View from the Window at Le Gras was the example of a camera photograph. Bauer encouraged him to present his heliography process to the Royal Society, before returning to France, Niépce gave his paper and the specimens to Bauer. Niépce died suddenly in 1833, due to a stroke, on March 9,1839, the specimens were finally exhibited at the Royal Society. After Bauers death in 1840 they passed through several hands and were exhibited as historical curiosities. View from the Window at Le Gras was last seen in 1905, historian Helmut Gernsheim tracked down the photograph in 1952 and brought it to prominence, reinforcing the claim that Niépce is the inventor of photography. Gernsheim heavily retouched one of the prints to clean it up and make the scene more comprehensible. During the 1950s and early 1960s, Gernsheim lent the photograph to several exhibitions in continental Europe, in 1963, Harry Ransom purchased most of Gernsheims photography collection for the University of Texas at Austin. The Niépce heliograph was not included in the sale, but shortly afterward Gernsheim donated it, although it has rarely traveled since then, in 2012–13 it visited Mannheim, Germany, as part of an exhibition entitled The Birth of Photography—Highlights of the Helmut Gernsheim Collection. It is normally on display in the lobby of the Harry Ransom Humanities Research Center in Austin. They confirmed that the image consists of bitumen and that the plate is pewter. The Institute also designed and built the elaborate display case system that now houses the artifact in a continuously monitored, stabilized, in 2007, scientists from the Louvre Museum published an analysis of the photograph using ion beam analysis, with data taken on their 2 MV electrostatic accelerator. This showed the details of the process that was corroding the image
25.
Louis Daguerre
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Louis-Jacques-Mandé Daguerre was a French artist and photographer, recognized for his invention of the daguerreotype process of photography. He became known as one of the fathers of photography, though he is most famous for his contributions to photography, he was also an accomplished painter and a developer of the diorama theatre. Louis Daguerre was born in Cormeilles-en-Parisis, Val-dOise, France and he was apprenticed in architecture, theatre design, and panoramic painting to Pierre Prévost, the first French panorama painter. Exceedingly adept at his skill of theatrical illusion, he became a designer for the theatre, and later came to invent the diorama. In 1829, Daguerre partnered with Nicéphore Niépce, an inventor who had produced the worlds first heliograph in 1822, Niépce died suddenly in 1833, but Daguerre continued experimenting, and evolved the process which would subsequently be known as the daguerreotype. After efforts to interest private investors proved fruitless, Daguerre went public with his invention in 1839, under assurances of strict confidentiality, Daguerre explained and demonstrated the process only to the Academys perpetual secretary François Arago, who proved to be an invaluable advocate. Members of the Academy and other individuals were allowed to examine specimens at Daguerres studio. The images were enthusiastically praised as nearly miraculous, and news of the daguerreotype quickly spread, in 1839, he was elected to the National Academy of Design as an Honorary Academician. Daguerre died on 10 July 1851 in Bry-sur-Marne,12 km from Paris, a monument marks his grave there. Daguerres name is one of the 72 names inscribed on the Eiffel tower, in the mid-1820s, prior to his association with Daguerre, Niépce used a coating of bitumen of Judea to make the first permanent camera photographs. The bitumen was hardened where it was exposed to light and the portion was then removed with a solvent. A camera exposure lasting for hours or days was required, Niépce and Daguerre later refined this process, but unacceptably long exposures were still needed. After the death of Niépce in 1833, Daguerre concentrated his attention on the properties of silver salts. The plate was exposed in the camera. Upon seeing the image, the contents of which are unknown, Daguerre said, the latent image on a daguerreotype plate was developed by subjecting it to the vapor given off by mercury heated to 75 °C. The resulting visible image was then fixed by removing the silver iodide with concentrated and heated salt water. Later, a solution of the more effective hypo was used instead, the resultant plate produced an exact reproduction of the scene. The image was laterally reversed—as images in mirrors are—unless a mirror or inverting prism was used during exposure to flip the image, daguerreotypes were usually portraits, the rarer landscape views and other unusual subjects are now much sought-after by collectors and sell for much higher prices than ordinary portraits
26.
Daguerreotype
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Daguerreotype process, or daguerreotypy, was the first publicly available photographic process, and for nearly twenty years it was the one most commonly used. During the past few decades, there has been a revival of daguerreotypy among photographers interested in making artistic use of early photographic processes. The darkest areas of the image are simply bare silver, lighter areas have a microscopically fine light-scattering texture, the surface is very delicate, and even the lightest wiping can permanently scuff it. Some tarnish around the edges is normal, the name daguerreotype correctly refers only to one very specific image type and medium, the product of a process that was in wide use only from the early 1840s to the late 1850s. Since the Renaissance era, artists and inventors had searched for a method of capturing visual scenes. Later, with the advent of Modernism, the absence of perspective in art from China, Japan. To copy these images was the first object of Mr. Daguerre met with Niépce, Niépce had invented an early internal combustion engine together with his brother Claude and made improvements to the velocipede, as well as experimenting with lithography and related processes. Their correspondence reveals that Niépce was at first reluctant to any details of his work with photographic images. To guard against letting any secrets out before the invention had been improved,15, for example, signified the tanning action of the sun on human skin,34 - a camera obscura,74 - sulphuric acid. Niépce undertook to release details of the process he had invented - the asphalt process or heliography, Daguerre was sworn to secrecy under penalty of damages, and undertook to design a camera and improve the process. The improved process was named the physautotype. Niépces early experiments had derived from his interest in lithography, the asphalt process, or heliography required exposures that were so long that Arago said it was not fit for use. Nevertheless, without Niépces experiments, it is unlikely that Daguerre would have been able to build on them to adapt, after Niépces death in 1833, his son, Isidore, inherited rights in the contract and a new version was drawn up between Daguerre and Isidore. It would bear Daguerres name alone and this was the daguerreotype process that used iodized silvered plates and was developed with mercury fumes. To exploit the invention four hundred shares would be on offer for a thousand francs each, or, the rights of the process could be bought for twenty thousand francs. Everyone says it is superb, but it will cost us the thousand francs before we learn it and be able to judge if it could remain secret. M. de Mandelot himself knows several persons who could subscribe but will not do so because they think it would be revealed by itself, and now I have proof that many think in this way. I entirely agree with the idea of M. Arago, that is get the government to purchase this discovery, nevertheless, he benefited from the state pension awarded to him together with Daguerre
27.
Royal Institution
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The Royal Institution of Great Britain is an organisation devoted to scientific education and research, based in London. Since its founding it has based at 21 Albemarle Street in Mayfair. Its Royal Charter was granted in 1800, throughout its history, the Institution has supported public engagement with science through a program of lectures, many of which continue today. The most famous of these are the annual Royal Institution Christmas Lectures, the Institution has had an instrumental role in the advancement of science since its founding. In the 19th century, Faraday carried out much of the research which laid the groundwork for the exploitation of electricity at the Royal Institution. In total fifteen scientists attached to the Royal Institution have won Nobel Prizes, the leadership of the Royal Institution has had various titles, Director of the Laboratory Director of the Davy-Faraday Research Laboratory Director The position was abolished in 2010. The Institutions last director was Susan Greenfield, following various resignations and general meetings of members, Andrade was awarded £7,000 by arbitration, the arbitrators blamed the problems on a lack of clear definition of roles. An outdated constitution, and the inability of the protagonists to compromise, Andrade launched a lawsuit to set the arbitration aside, which he lost. From 1998 to 8 January 2010, the director of the Royal Institution was Baroness Susan Greenfield, but following a review, the project ended £3 million in debt. Greenfield subsequently announced that she would be suing for discrimination, Baroness Greenfield later dropped the discrimination case. Today the Royal Institution is committed to diffusing science for the purposes of life. Membership is open to all, with no nomination procedure or academic requirements, the institutions palatial home has been greatly enlarged and redeveloped since 1799, and is a Grade I listed building. The structures last refurbishment was a £22 million project completed in 2008, as well as the famous Lecture Theatre, the building contains several function rooms, modern research facilities and a public café. The trustees were considering selling the building in an effort to recoup the organisations debts, in 2013 The Ri received an anonymous donation of £4. 4m and as of January 2016, the Ri is now debt-free. The Institution has a public science programme and science for schools programme. The Christmas Lectures continue today as a series of three televised lectures aimed at children, the Friday Evening Discourses are monthly lectures given by eminent scientists, each limited to exactly one hour, a tradition started by Faraday. There is a members ballot for tickets to the Christmas Lectures. Discounts are available to Ri Patrons and Members, many other events and lectures are held both at Albemarle Street and at other venues around the country
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Silver nitrate
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Silver nitrate is an inorganic compound with chemical formula AgNO3. This compound is a precursor to many other silver compounds. It is far less sensitive to light than the halides and it was once called lunar caustic because silver was called luna by the ancient alchemists, who believed that silver was associated with the moon. In solid silver nitrate, the ions are three-coordinated in a trigonal planar arrangement. Albertus Magnus, in the 13th century, documented the ability of nitric acid to separate gold, Magnus noted that the resulting solution of silver nitrate could blacken skin. Silver nitrate can be prepared by reacting silver, such as a silver bullion or silver foil, with acid, resulting in silver nitrate, water. Reaction byproducts depend upon the concentration of acid used. 3 Ag +4 HNO3 →3 AgNO3 +2 H2O + NO Ag +2 HNO3 → AgNO3 + H2O + NO2 This is performed under a fume hood because of nitrogen oxide evolved during the reaction. A typical reaction with silver nitrate is to suspend a rod of copper in a solution of silver nitrate, silver nitrate is the least expensive salt of silver, it offers several other advantages as well. It is non-hygroscopic, in contrast to silver fluoroborate and silver perchlorate and it is relatively stable to light. Finally, it dissolves in solvents, including water. The nitrate can be replaced by other ligands, rendering AgNO3 versatile. Treatment with solutions of halide ions gives a precipitate of AgX, similarly, silver nitrate is used to prepare some silver-based explosives, such as the fulminate, azide, or acetylide, through a precipitation reaction. This reaction is used in inorganic chemistry to abstract halides, Ag+ + X− → AgX where X− = Cl−, Br−. Other silver salts with non-coordinating anions, namely silver tetrafluoroborate and silver hexafluorophosphate are used for demanding applications. Similarly, this reaction is used in chemistry to confirm the presence of chloride, bromide. Samples are typically acidified with nitric acid to remove interfering ions, e. g. carbonate ions. This step avoids confusion of silver sulfide or silver carbonate precipitates with that of silver halides, the color of precipitate varies with the halide, white, pale yellow/cream, yellow
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Silver chloride
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Silver chloride is a chemical compound with the chemical formula AgCl. This white crystalline solid is known for its low solubility in water. Upon illumination or heating, silver chloride converts to silver, which is signaled by greyish or purplish coloration to some samples, AgCl occurs naturally as a mineral chlorargyrite. Silver chloride is synthesized by combining aqueous solutions of silver nitrate. AgNO3 + NaCl ⟶ AgCl ↓ + NaNO3 The solid adopts the fcc NaCl structure, however, the crystallography depends on the condition of crystallization, primarily free silver ion concentration, as is shown on the pictures left. AgCl dissolves in solutions containing ligands such as chloride, cyanide, triphenylphosphine, thiosulfate, thiocyanate, most complexes derived from AgCl are two-, three-, and, in rare cases, four-coordinate, adopting linear, trigonal planar, and tetrahedral coordination geometries, respectively. Due to its conspicuousness it is used in titration, which gives the typical case of argentometry. The solubility product, Ksp, for AgCl in water is 1. 77×10−10 at room temperature, ions that interfere with this test are bromide and iodide, as well as a variety of ligands. For AgBr and AgI, the Ksp values are 5.2 x 10−13 and 8.3 x 10−17, silver bromide and silver iodide are also significantly more photosensitive than is AgCl. AgCl quickly darkens on exposure to light by disintegrating into elemental chlorine and this reaction is used in photography and film. The silver chloride electrode is a reference electrode in electrochemistry. Silver chlorides low solubility makes it an addition to pottery glazes for the production of Inglaze lustre. Silver chloride has been used as an antidote for poisoning, assisting in the elimination of mercury
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Photogram
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A photogram is a photographic image made without a camera by placing objects directly onto the surface of a light-sensitive material such as photographic paper and then exposing it to light. The usual result is a shadow image that shows variations in tone that depends upon the transparency of the objects used. Areas of the paper that have received no light appear white, the technique is sometimes called cameraless photography. It was used by Man Ray in his exploration of rayographs, other artists who have experimented with the technique include László Moholy-Nagy, Christian Schad, Imogen Cunningham and Pablo Picasso. Variations of the technique have also used for scientific purposes. Some of the first photographic images made were photograms, william Henry Fox Talbot called these photogenic drawings, which he made by placing leaves and pieces of material onto sensitized paper, then left them outdoors on a sunny day to expose. This produced a background with a white silhouette of the object used. From 1843, Anna Atkins produced a book titled British Algae, Cyanotype Impressions in installments, the images were all photograms of botanical specimens, which she made using Sir John Herschels cyanotype process, which yields blue images. This very rare book can be seen in the National Media Museum in Bradford, photograms were used in the 20th century by a number of photographers, particularly Man Ray, who called them rayographs. Contemporary artists who are known for using photograms are Adam Fuss, Susan Derges. In a darkroom, or a room, objects are arranged on top a piece of photographic material. When the operator is satisfied with the arrangement, the material is exposed with light. The material is processed, washed and dried. Drawn-on-film animation, another form of cameraless image making Neues Sehen, László Moholy-Nagys New Vision photography movement
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Lens (optics)
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A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a piece of transparent material, while a compound lens consists of several simple lenses. Lenses are made from such as glass or plastic, and are ground. A lens can focus light to form an image, unlike a prism, devices that similarly focus or disperse waves and radiation other than visible light are also called lenses, such as microwave lenses, electron lenses, acoustic lenses, or explosive lenses. The word lens comes from the Latin name of the lentil, the genus of the lentil plant is Lens, and the most commonly eaten species is Lens culinaris. The lentil plant also gives its name to a geometric figure, the variant spelling lense is sometimes seen. While it is listed as a spelling in some dictionaries. The oldest lens artifact is the Nimrud lens, dating back 2700 years to ancient Assyria, david Brewster proposed that it may have been used as a magnifying glass, or as a burning-glass to start fires by concentrating sunlight. Another early reference to magnification dates back to ancient Egyptian hieroglyphs in the 8th century BC, the earliest written records of lenses date to Ancient Greece, with Aristophanes play The Clouds mentioning a burning-glass. Some scholars argue that the evidence indicates that there was widespread use of lenses in antiquity. Such lenses were used by artisans for fine work, and for authenticating seal impressions, both Pliny and Seneca the Younger described the magnifying effect of a glass globe filled with water. The Viking lenses were capable of concentrating enough sunlight to ignite fires, between the 11th and 13th century reading stones were invented. Often used by monks to assist in illuminating manuscripts, these were primitive plano-convex lenses initially made by cutting a sphere in half. As the stones were experimented with, it was understood that shallower lenses magnified more effectively. Lenses came into use in Europe with the invention of spectacles. Spectacle makers created improved types of lenses for the correction of vision based more on knowledge gained from observing the effects of the lenses. With the invention of the telescope and microscope there was a deal of experimentation with lens shapes in the 17th. Opticians tried to construct lenses of varying forms of curvature, wrongly assuming errors arose from defects in the figure of their surfaces
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Camera obscura
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The surroundings of the projected image have to be relatively dark for the image to be clear, so many historical camera obscura experiments were performed in dark rooms. The term camera obscura also refers to constructions or devices that use of the principle within a box. Camerae obscurae with a lens in the opening have been used since the second half of the 16th century, before the term camera obscura was first used in 1604, many other expressions were used including cubiculum obscurum, cubiculum tenebricosum, conclave obscurum and locus obscurus. Rays of light travel in straight lines and change when they are reflected and partly absorbed by an object, retaining information about the color, lit objects reflect rays of light in all directions. The human eye itself works much like a camera obscura with an opening, a biconvex lens, a camera obscura device consists of a box, tent or room with a small hole in one side. Light from a scene passes through the hole and strikes a surface inside, where the scene is reproduced, inverted and reversed. The image can be projected onto paper, and can then be traced to produce an accurate representation. In order to produce a reasonably clear projected image, the aperture has to be about 1/100th the distance to the screen, many camerae obscurae use a lens rather than a pinhole because it allows a larger aperture, giving a usable brightness while maintaining focus. As the pinhole is made smaller, the image gets sharper, with too small a pinhole, however, the sharpness worsens, due to diffraction. Using mirrors, as in an 18th-century overhead version, it is possible to project a right-side-up image, another more portable type is a box with an angled mirror projecting onto tracing paper placed on the glass top, the image being upright as viewed from the back. There are theories that occurrences of camera obscura effects inspired paleolithic cave paintings and it is also suggested that camera obscura projections could have played a role in Neolithic structures. Perforated gnomons projecting an image of the sun were described in the Chinese Zhoubi Suanjing writings. The location of the circle can be measured to tell the time of day. In Arab and European cultures its invention was later attributed to Egyptian astronomer. Some ancient sightings of gods and spirits, especially in worship, are thought to possibly have been conjured up by means of camera obscura projections. In these writings it is explained how the image in a collecting-point or treasure house is inverted by an intersecting point that collected the light. Light coming from the foot of a person would partly be hidden below. Rays from the head would partly be hidden above and partly form the part of the image
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Thomas Wedgwood (photographer)
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Thomas Wedgwood, son of Josiah Wedgwood, the potter, is most widely known as an early experimenter in the field of photography. He is the first person known to have thought of creating permanent pictures by capturing camera images on material coated with a light-sensitive chemical, thomas Wedgwood was born in Etruria, Staffordshire, now part of the city of Stoke-on-Trent in England. Wedgwood was born into a line of pottery manufacturers, grew up and was educated at Etruria and was instilled from his youth with a love for art. He also spent much of his short life associating with painters, sculptors, as a young adult, Wedgwood became interested in the best method of educating children, and spent time studying infants. From his observations, he concluded that most of the information that young brains absorbed came through the eyes, Wedgwood never married and had no children. In imperfect health as a child and a chronic invalid as an adult, the date of his first experiments in photography is unknown, but he is believed to have indirectly advised James Watt on the practical details prior to 1800. In his many experiments, possibly with advice on chemistry from his tutor Alexander Chisholm and members of the Lunar Society, Wedgwood used paper, the leather proved to be more light-sensitive. His primary objective had been to capture real-world scenes with a camera obscura, in both cases, the sunlit areas rapidly darkened while the areas in shadow did not. Wedgwood met a young chemist named Humphry Davy at the Pneumatic Clinic in Bristol, the paper was published and detailed Wedgwood’s procedures and accomplishments, as well as Davys own variations of them. the Journal did not live beyond a first volume. David Brewster, later a friend of photography pioneer Henry Fox Talbot. The paper was translated into French, and also printed in Germany in 1811, reades work in 1839 was directly influenced by reading of Wedgwoods more rapid results when using leather. Reade tried treating paper with an agent used in making leather. Reades discovery was communicated to Talbot by a friend, as was proven in a court case over patents. Wedgwood was unable to fix his pictures to make them immune to the effects of light. Unless kept in darkness, they would slowly but surely darken all over. As Davy put it in his paper of 1802, the picture, immediately after being taken, must be kept in some obscure place. It may indeed be examined in the shade, but in case the exposure should be only for a few minutes, by the light of candles and lamps, as commonly employed. In 1839, John Herschel pointed out his earlier published discovery that hyposulphite of soda dissolved silver halides and this allowed the remaining light-sensitive silver salts to be completely washed away, truly fixing the photograph
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David Octavius Hill
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David Octavius Hill was a Scottish painter and arts activist. He formed Hill & Adamson studio with the engineer and photographer Robert Adamson between 1843 and 1847 to pioneer many aspects of photography in Scotland, David Octavius Hill was born in 1802 in Perth. His father, a bookseller and publisher, helped to re-establish Perth Academy, when his older brother Alexander joined the publishers Blackwoods in Edinburgh, David went there to study at the School of Design. He learned lithography and produced Sketches of Scenery in Perthshire which was published as an album of views, a year later Hill took on unpaid secretarial duties. In the 1830s he is listed as living at 24 Queen Street, charlotte married the author Walter Scott Dalgleish. Ann died on 5 October 1841, aged only 36 and she is buried with her family in Greyfriars Churchyard in Perth. Hill then spent some twenty years as a bachelor and he continued to produce illustrations and to paint landscapes on commission. During this perion he lived at 28 Inverleith Row in Edinburghs northern suburbs, Hill was present at the Disruption Assembly in 1843 when over 450 ministers walked out of the Church of Scotland assembly and down to another assembly hall to found the Free Church of Scotland. Brewster was himself experimenting with technology which only dated back to 1839. Hill and Adamson took a series of photographs of those who had been present, the 5 foot x 11 foot 4 inches painting was eventually completed in 1866. Hill moved to Calton Hill Stairs in 1850, adamsons studio, Rock House, on Calton Hill in Edinburgh became the centre of their photographic experiments. They photographed local and Fife landscapes and urban scenes, including images of the Scott Monument under construction in Edinburgh and they produced several groundbreaking action photographs of soldiers and - perhaps their most famous photograph - two priests walking side by side. Their partnership produced around 3,000 prints, but was cut short after four years due to the ill health and death of Adamson in 1848. He was badly affected by the death of his daughter and his work slowed, in 1866 he finished the Disruption picture which received wide acclaim, though many of the participants had died by then. The photographer F. C. Annan produced fine reduced facsimiles of the painting for sale throughout the Free Church, in 1869 illness forced him to give up his post as secretary to the R. S. A. and he died in May 1870. Hill is buried in Dean Cemetery, Edinburgh - one of the finest Victorian cemeteries in Scotland and he is portrayed in a bust sculpted by his second wife, Amelia, who is buried alongside him. Michaelson, Katherine, David Octavius Hill and Robert Adamson, catalogue for Scottish Arts Council exhibitions,1970, works in the National Galleries of Scotland Metropolitan Museum of Art - David Octavius Hill and Robert Adamson
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Silver iodide
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Silver iodide is an inorganic compound with the formula AgI. The compound is a yellow solid, but samples almost always contain impurities of metallic silver that give a gray coloration. The silver contamination arises because AgI is highly photosensitive and this property is exploited in silver-based photography. Silver iodide is used as an antiseptic and in cloud seeding. The structure adopted by silver iodide is temperature dependent, Below 420 K and this phase is encountered in nature as the mineral iodargyrite. Above 420 K, the α-phase becomes more stable and this motif is a body-centered cubic structure which has the silver centers distributed randomly between 6 octahedral,12 tetrahedral and 24 trigonal sites. At this temperature, Ag+ ions can move rapidly through the solid, the transition between the β and α forms represents the melting of the silver sublattice. The entropy of fusion for α-AgI is approximately half that for sodium chloride and this can be rationalized by considering the AgI crystalline lattice to have already partly melted in the transition between α and β polymorphs. A metastable γ-phase also exists below 420 K with the zinc blende structure, silver iodide is prepared by reaction of an iodide solution with a solution of silver ions. The solid is a mixture of the two principal phases, dissolution of the AgI in hydroiodic acid, followed by dilution with water precipitates β-AgI. Alternatively, dissolution of AgI in a solution of concentrated silver nitrate followed by dilution affords α-AgI, if the preparation is not conducted in the absence of sunlight, the solid darkens rapidly, the light causing the reduction of ionic silver to metallic. The photosensitivity varies with sample purity, the crystalline structure of β-AgI is similar to that of ice, allowing it to induce freezing by the process known as heterogeneous nucleation. Approximately 50,000 kg are used for cloud seeding annually, extreme exposure can lead to argyria, characterized by localized discoloration of body tissue
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Gallic acid
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Gallic acid is a trihydroxybenzoic acid, a type of phenolic acid, found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants. The chemical formula of gallic acid is C6H23COOH and it is found both free and as part of hydrolyzable tannins. The gallic acid groups are bonded to form dimers such as ellagic acid. Hydrolyzable tannins break down on hydrolysis to give gallic acid and glucose or ellagic acid and glucose, known as gallotannins and ellagitannins, gallic acid forms intermolecular esters such as digallic and trigallic acids, and cyclic ether-esters. Gallic acid can also be used as a material in the synthesis of the psychedelic alkaloid mescaline. The name is derived from oak galls, which were used to prepare tannic acid. Despite the name, gallic acid does not contain gallium, salts and esters of gallic acid are termed gallates. Pliny the Elder describes his experiments with it and writes that it was used to produce dyes, galls from oak trees were crushed and mixed with water, producing tannic acid. Gallic acid was one of the used by Angelo Mai, among other early investigators of palimpsests, to clear the top layer of text off. Mai was the first to employ it, but did so with a heavy hand, gallic acid was first studied by the Swedish chemist Carl Wilhelm Scheele in 1786. Gallic acid is a component of some pyrotechnic whistle mixtures, gallic acid is formed from 3-dehydroshikimate by the action of the enzyme shikimate dehydrogenase to produce 3, 5-didehydroshikimate. This latter compound tautomerizes to form the redox equivalent gallic acid, gallate dioxygenase is an enzyme found in Pseudomonas putida that catalyses the reaction gallate + O2 → -4-oxobut-1-ene-1,2, 4-tricarboxylate. Gallate decarboxylase is another enzyme in the degradation of gallic acid, gallate 1-beta-glucosyltransferase is an enzyme that uses UDP-glucose and gallate, whereas its two products are UDP and 1-galloyl-beta-D-glucose. It is a carbonic anhydrase inhibitor. In basic research, gallic acid extracted from seeds has been shown to inhibit the formation of amyloid fibrils, one of the potential causes of Alzheimers disease. One study indicated that gallic acid has this effect on amyloid protein formation by modifying the properties of alpha-synuclein, gallic acid is classified as a mutagen and a teratogen. Gallic acid is found in a number of plants, such as the parasitic plant Cynomorium coccineum, the aquatic plant Myriophyllum spicatum. Gallic acid is found in various oak species, Caesalpinia mimosoides
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Latent image
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A latent image is an invisible image produced by the exposure to light of a photosensitive material such as photographic film. When photographic film is developed, the area that was exposed darkens, in more physical terms, a latent image is a small cluster of metallic silver atoms formed in or on a silver halide crystal due to reduction of interstitial silver ions by photoelectrons. If intense exposure continues, such photolytic silver clusters grow to visible sizes and this is called printing out the image. On the other hand, the formation of an image by the action of photographic developer is called developing out the image. The size of a cluster in the latent image can be as small as a few silver atoms. However, in order to act as a latent image center. On the other hand, a developed silver grain can have billions of silver atoms, therefore, photographic developer acting on the latent image is a chemical amplifier with a gain factor up to several billion. The development system was the most important technology that increased the sensitivity in the history of photography. The action of the light on the silver halide grains within the emulsion forms sites of metallic silver in the grains, the basic mechanism by which this happens was first proposed by R W Gurney and N F Mott in 1938. The incoming photon liberates an electron, called a photoelectron, from a silver halide crystal, photoelectrons migrate to a shallow electron trap site, where the electrons reduce silver ions to form a metallic silver speck. A positive hole must also be generated but it is largely ignored, subsequent work has slightly modified this picture, so that hole trapping is also considered. Since then, understanding of the mechanism of sensitivity and latent image formation has been greatly improved, one very important way to increase photographic sensitivity is to manipulate the electron traps in each crystal. A pure, defect-free crystal exhibits poor photographic sensitivity, since it lacks a shallow electron trap that facilitates the formation of a latent image, in such a case, many of the photoelectrons will recombine with the silver halide crystal and be wasted. Shallow electron traps are created by sulfur sensitization, introduction of a crystalline defect, the location, kind and number of shallow traps have a huge influence on the efficiency by which the photoelectrons create latent image centers, and consequently, on photographic sensitivity. Another important way to increase photographic sensitivity is to reduce the size of developable latent images. Gold sensitization of Koslowski creates metallic gold specks on the crystal surface, when a latent image is formed around the gold speck, the presence of gold is known to reduce the number of metallic silver atoms necessary to render the crystal developable. Another important concept in increasing photographic sensitivity is to separate photoholes away from photoelectrons and this should reduce the probability of recombination. Reduction sensitization is one implementation of this concept
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Transparency and translucency
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In the field of optics, transparency is the physical property of allowing light to pass through the material without being scattered. On a macroscopic scale, the photons can be said to follow Snells Law, in other words, a translucent medium allows the transport of light while a transparent medium not only allows the transport of light but allows for image formation. The opposite property of translucency is opacity, transparent materials appear clear, with the overall appearance of one color, or any combination leading up to a brilliant spectrum of every color. When light encounters a material, it can interact with it in different ways. These interactions depend on the wavelength of the light and the nature of the material, photons interact with an object by some combination of reflection, absorption and transmission. Some materials, such as glass and clean water, transmit much of the light that falls on them and reflect little of it. Many liquids and aqueous solutions are highly transparent, absence of structural defects and molecular structure of most liquids are mostly responsible for excellent optical transmission. Materials which do not transmit light are called opaque, many such substances have a chemical composition which includes what are referred to as absorption centers. Many substances are selective in their absorption of light frequencies. They absorb certain portions of the spectrum while reflecting others. The frequencies of the spectrum which are not absorbed are either reflected or transmitted for our physical observation and this is what gives rise to color. The attenuation of light of all frequencies and wavelengths is due to the mechanisms of absorption. Transparency can provide almost perfect camouflage for animals able to achieve it and this is easier in dimly-lit or turbid seawater than in good illumination. Many marine animals such as jellyfish are highly transparent, at the atomic or molecular level, physical absorption in the infrared portion of the spectrum depends on the frequencies of atomic or molecular vibrations or chemical bonds, and on selection rules. Nitrogen and oxygen are not greenhouse gases because there is no absorption because there is no molecular dipole moment. With regard to the scattering of light, the most critical factor is the scale of any or all of these structural features relative to the wavelength of the light being scattered. Primary material considerations include, Crystalline structure, whether or not the atoms or molecules exhibit the long-range order evidenced in crystalline solids, glassy structure, scattering centers include fluctuations in density or composition. Microstructure, scattering centers include internal surfaces such as boundaries, crystallographic defects
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Contact print
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A contact print is a photographic image produced from film, sometimes from a film negative, and sometimes from a film positive. The defining characteristic of a print is that the resulting print is the same size as the original. One or more negatives are placed in contact with a sheet of sensitized photographic paper. The negative and the paper are then placed, negative side down. Within the box and below the top plate is a translucent light diffuser made from frosted glass, below the diffuser is a switch-controlled electric light source. A hinged top-cover keeps the materials in contact and reduces or eliminates the amount of stray light allowed into the darkroom. Ansel Adams describes procedures for making prints using ordinary lighting in his book. The contact printer is used to expose the image onto the paper for a few seconds. The operator may use a switch and count off the seconds himself. The black and white gelatin-silver process may be using a safelight for darkroom illumination. The contact printer may also contain a safelight so that the negative can be examined before the paper is laid upon it. After exposure, the paper is processed using chemicals in the darkroom to produce the final print, the paper must be placed in a film developer bath, a stop bath, fixer, and finally the hypo-eliminator bath, in that order. Failure to adhere precisely to this process will result in a poor-quality final image with a variety of issues, since this process produces neither enlargements nor reductions, the image on the print is exactly the same size as the image on the negative. For 120 roll film and larger film, contact prints are used to determine the final print size. In medium and large format photography, contact prints are prized for their fidelity to the negative. A disadvantage to using contact prints in the fine-arts is the laboriousness of modifying exposure selectively, however, the exposure value range, the variation from darkest to lightest regions, is inherently greater in negatives than in prints. When large format film is printed to create finished work, it is possible. Burning and dodging require painstaking work with masks, or the use of a production contact printing machine
This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Talbot, William Henry Fox". Encyclopædia Britannica. 26 (11th ed.). Cambridge University Press.
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