1.
1846 in science
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The year 1846 in science and technology involved some significant events, listed below. February 20 – Francesco de Vico discovers comet 122P/de Vico, june 1 – Urbain Le Verrier predicts the existence and location of Neptune from irregularities in the orbit of Uranus. August 8 – Neptune observed but not recognised by James Challis, august 31 – Urbain Le Verrier publishes full details of the predicted orbit and the mass of the new planet. September 23 – Johann Galle discovers Neptune, october 10 – William Lassell discovers Triton, Neptunes largest moon. Royal Botanic Gardens, Melbourne, established in Australia, abraham Pineo Gesner develops a process to refine a liquid fuel, which he calls kerosene, from coal, bitumen or oil shale. December 21 – British surgeon Robert Liston carries out the first operation under anesthesia in Europe, dr J. Collis Browne formulates his laudanum-based pain-relieving Chlorodyne compound while serving in the British Indian Army. January 13 – Opening of the Milan–Venice railways 3.2 km bridge over the Venetian Lagoon between Mestre and Venice in Italy, the worlds longest since 1151, june 28 – Adolphe Sax patents the saxophone. September 10 – Elias Howe is awarded the first United States patent for a machine using a lockstitch design. Scottish-born engineer Robert William Thomson is granted his first patent for a pneumatic tyre, William Armstrongs first hydraulic crane is erected at Newcastle upon Tyne in England. Squire Whipple introduces the trapezoidal Whipple truss for bridges in the United States, copley Medal, Urbain Le Verrier Wollaston Medal, William Lonsdale September 16 – Anna Kingsford, English physician, anti-vivisectionist and vegetarian. December 12 – Eugen Baumann, German chemist, january 30 – Joseph Carpue English surgeon. March 17 – Friedrich Bessel, German mathematician, october 2 – Benjamin Waterhouse, American physician. John Bostock, English physician and geologist
2.
1851 in science
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The year 1851 in science and technology involved some significant events, listed below. February – First public exhibition of a Foucault pendulum, at the Meridian of the Paris Observatory, a few weeks later Foucault installs one at the Panthéon. July 28 – Solar eclipse of July 28,1851, Total solar eclipse, the first correctly exposed photograph, a daguerrotype, of the solar corona is made during the total phase of the eclipse by Berkowski at Koenigsberg Observatory in Prussia. October 24 – Ariel and Umbriel, moons of Uranus, are discovered by William Lassell, the William Brydone Jack Observatory is completed at Fredericton, New Brunswick. March – English sculptor Frederick Scott Archer makes public the wet collodion photographic process. George Wilson publishes The Life of the Hon. Henry Cavendish, bernhard Riemann provides a proof of Greens theorem in his inaugural dissertation. The Royal Marsden is established as the Free Cancer Hospital by surgeon William Marsden in London, hippolyte Fizeau carries out the Fizeau experiment to measure the relative speeds of light in moving water. November 13 – First protected submarine telegraph cable laid, across the English Channel, William Armstrong introduces the weight-loaded hydraulic accumulator. Copley Medal, Richard Owen Wollaston Medal for geology, Adam Sedgwick January 19 – Jacobus Kapteyn, march 16 – Martinus Beijerinck, Dutch microbiologist and botanist. April 12 – E. Walter Maunder, astronomer, July 8 – Arthur Evans, archaeologist. July 20 – Arnold Pick, neurologist, august 3 – George FitzGerald, mathematician. January 27 – John James Audubon, naturalist and illustrator, february 18 – Carl Gustav Jakob Jacobi, mathematician. March 9 – Hans Christian Ørsted, physicist, July 6 – Thomas Davenport, electrical engineer. July 17 – John Farey, mechanical engineer and technical writer, september 2 – William Nicol, geologist
3.
1852 in science
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The year 1852 in science and technology involved some significant events, listed below. September 24 – French engineer Henri Giffard makes the first airship trip, last recognised sighting of a great auk, on the Grand Banks of Newfoundland. August Beer proposes Beers law, which explains the relationship between the composition of a mixture and the amount of light it will absorb, based partly on earlier work by Pierre Bouguer and Johann Heinrich Lambert, it establishes the analytical technique known as spectrophotometry. October 23 – Francis Guthrie poses the four colour problem to Augustus De Morgan, january 15 – Nine representatives of Hebrew charitable organizations come together to form what will become the Mount Sinai Hospital, New York. February 15 – The Great Ormond Street Hospital for Sick Children, London, march 2 – The first American experimental steam fire engine is tested. The mechanical semaphore line in France is superseded by the electric telegraph, captain E. M. Boxer of the Royal Arsenal devizes an improvement to the shrapnel shell by insertion of an iron diaphragm, preventing premature ignition. Copley Medal, Alexander von Humboldt Wollaston Medal for Geology, William Henry Fitton April 10 – Arthur Vierendeel, may 1 – Santiago Ramón y Cajal, Spanish neuroscientist, winner of the Nobel Prize in Physiology or Medicine. August 4 – Catharine van Tussenbroek, Dutch physician, august 30 – Jacobus van t Hoff, Dutch chemist. September 9 – John Henry Poynting, English physicist, discoverer of the Poynting–Robertson effect, september 28 – Isis Pogson, English astronomer and meteorologist. October 2 – William Ramsay, Scottish winner of the Nobel Prize in Chemistry, october 9 – Hermann Emil Fischer, German winner of the Nobel Prize in Chemistry. December 15 – Henri Becquerel, French physicist, january 6 – Louis Braille, French inventor. August 15 – Johan Gadolin, Finnish chemist, september 8 – Anna Maria Walker, Scottish botanist. November 10 – Gideon Mantell, English paleontologist, november 27 – Augusta Ada King, Countess of Lovelace, English computing pioneer
4.
1843 in architecture
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The year 1843 in architecture involved some significant events. March 25 - The Thames Tunnel in London, constructed by Isambard Kingdom Brunel and Marc Isambard Brunel, nelsons Column in London, designed by William Railton, is completed. McGill Universitys original building, later known as the Arts Building, is completed in Montreal by architect John Ostell, grand Prix de Rome, architecture, Jacques-Martin Tétaz. July 6 - Robert S. Roeschlaub, German-born architect working in Colorado November 29 - Gertrude Jekyll, English garden designer January 13 - Peter Atkinson, English-born architect
5.
1843 in music
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February 6 – The Virginia Minstrels perform the first minstrel show. November 13 – Gaetano Donizettis final opera Dom Sébastien is premiered at the Paris Opera, december 26 – Following the première of his last opera, Hernani, Alberto Mazzucato retires from composing in order to become a full-time music teacher. August Conradi becomes organist of the Invalidenhaus, Berlin, gottfried Kinkel marries fellow musician Johanna Mockel
6.
Science
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Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe. The formal sciences are often excluded as they do not depend on empirical observations, disciplines which use science, like engineering and medicine, may also be considered to be applied sciences. However, during the Islamic Golden Age foundations for the method were laid by Ibn al-Haytham in his Book of Optics. In the 17th and 18th centuries, scientists increasingly sought to formulate knowledge in terms of physical laws, over the course of the 19th century, the word science became increasingly associated with the scientific method itself as a disciplined way to study the natural world. It was during this time that scientific disciplines such as biology, chemistry, Science in a broad sense existed before the modern era and in many historical civilizations. Modern science is distinct in its approach and successful in its results, Science in its original sense was a word for a type of knowledge rather than a specialized word for the pursuit of such knowledge. In particular, it was the type of knowledge which people can communicate to each other, for example, knowledge about the working of natural things was gathered long before recorded history and led to the development of complex abstract thought. This is shown by the construction of calendars, techniques for making poisonous plants edible. For this reason, it is claimed these men were the first philosophers in the strict sense and they were mainly speculators or theorists, particularly interested in astronomy. In contrast, trying to use knowledge of nature to imitate nature was seen by scientists as a more appropriate interest for lower class artisans. A clear-cut distinction between formal and empirical science was made by the pre-Socratic philosopher Parmenides, although his work Peri Physeos is a poem, it may be viewed as an epistemological essay on method in natural science. Parmenides ἐὸν may refer to a system or calculus which can describe nature more precisely than natural languages. Physis may be identical to ἐὸν and he criticized the older type of study of physics as too purely speculative and lacking in self-criticism. He was particularly concerned that some of the early physicists treated nature as if it could be assumed that it had no intelligent order, explaining things merely in terms of motion and matter. The study of things had been the realm of mythology and tradition, however. Aristotle later created a less controversial systematic programme of Socratic philosophy which was teleological and he rejected many of the conclusions of earlier scientists. For example, in his physics, the sun goes around the earth, each thing has a formal cause and final cause and a role in the rational cosmic order. Motion and change is described as the actualization of potentials already in things, while the Socratics insisted that philosophy should be used to consider the practical question of the best way to live for a human being, they did not argue for any other types of applied science
7.
Technology
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Technology is the collection of techniques, skills, methods and processes used in the production of goods or services or in the accomplishment of objectives, such as scientific investigation. Technology can be the knowledge of techniques, processes, and the like, the human species use of technology began with the conversion of natural resources into simple tools. The steady progress of technology has brought weapons of ever-increasing destructive power. It has helped develop more advanced economies and has allowed the rise of a leisure class, many technological processes produce unwanted by-products known as pollution and deplete natural resources to the detriment of Earths environment. Various implementations of technology influence the values of a society and raise new questions of the ethics of technology, examples include the rise of the notion of efficiency in terms of human productivity, and the challenges of bioethics. Philosophical debates have arisen over the use of technology, with disagreements over whether technology improves the condition or worsens it. The use of the technology has changed significantly over the last 200 years. Before the 20th century, the term was uncommon in English, the term was often connected to technical education, as in the Massachusetts Institute of Technology. The term technology rose to prominence in the 20th century in connection with the Second Industrial Revolution, the terms meanings changed in the early 20th century when American social scientists, beginning with Thorstein Veblen, translated ideas from the German concept of Technik into technology. In German and other European languages, a distinction exists between technik and technologie that is absent in English, which translates both terms as technology. By the 1930s, technology referred not only to the study of the industrial arts, dictionaries and scholars have offered a variety of definitions. Ursula Franklin, in her 1989 Real World of Technology lecture, gave another definition of the concept, it is practice, the way we do things around here. The term is used to imply a specific field of technology, or to refer to high technology or just consumer electronics. Bernard Stiegler, in Technics and Time,1, defines technology in two ways, as the pursuit of life by other than life, and as organized inorganic matter. Technology can be most broadly defined as the entities, both material and immaterial, created by the application of mental and physical effort in order to some value. In this usage, technology refers to tools and machines that may be used to solve real-world problems and it is a far-reaching term that may include simple tools, such as a crowbar or wooden spoon, or more complex machines, such as a space station or particle accelerator. Tools and machines need not be material, virtual technology, such as software and business methods. W. Brian Arthur defines technology in a broad way as a means to fulfill a human purpose
8.
Ada Lovelace
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Augusta Ada King-Noel, Countess of Lovelace was an English mathematician and writer, chiefly known for her work on Charles Babbages proposed mechanical general-purpose computer, the Analytical Engine. She was the first to recognise that the machine had applications beyond pure calculation, as a result, she is often regarded as the first to recognise the full potential of a computing machine and the first computer programmer. Ada Lovelace was the legitimate child of the poet George, Lord Byron. All Byrons other children were out of wedlock to other women. Byron separated from his wife a month after Ada was born and left England forever four months later, often ill, she spent most of her childhood sick. Ada married William King in 1835, King was made Earl of Lovelace in 1838, and she became Countess of Lovelace. Ada described her approach as poetical science and herself as an Analyst, Lovelace first met him in June 1833, through their mutual friend, and her private tutor, Mary Somerville. Between 1842 and 1843, Ada translated an article by Italian military engineer Luigi Menabrea on the engine and these notes contain what many consider to be the first computer program—that is, an algorithm designed to be carried out by a machine. Lovelaces notes are important in the history of computers. She also developed a vision of the capability of computers to go beyond mere calculating or number-crunching, while others, including Babbage himself. Her mindset of poetical science led her to ask questions about the Analytical Engine examining how individuals and she died of uterine cancer in 1852 at the age of 36. Byron expected his baby to be a boy and was disappointed when his wife gave birth to a girl. Augusta was named after Byrons half-sister, Augusta Leigh, and was called Ada by Byron himself, on 16 January 1816 Adas mother, Annabella, at Byrons behest, left for her parents home at Kirkby Mallory taking one-month-old Ada with her. On 21 April Byron signed the Deed of Separation, although very reluctantly, aside from an acrimonious separation, Annabella continually made allegations about Byrons immoral behaviour throughout her life. This set of events made Ada famous in Victorian society, Byron did not have a relationship with his daughter, and never saw her again. He died in 1824 when she was eight years old and her mother was the only significant parental figure in her life. Ada was not shown the family portrait of her father until her twentieth birthday and her mother became Baroness Wentworth in her own right in 1856. Annabella did not have a relationship with the young Ada and often left her in the care of her own mother Judith
9.
Cabra, Dublin
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Cabra is a suburb on the northside of Dublin city in Ireland. It is approximately 2 kilometres northwest of the city centre, in the area of Dublin City Council. It was commonly known as Cabragh until the early 20th century, Cabra is also a parish in the Fingal South West deanery of the Roman Catholic Archdiocese of Dublin. Dublin Bus two main routes for the area are the 120 Ashtown via Cabra West/East to Parnell Street/Ballsbridge and 122 Ashington, Cabra West/East, routes 38/a/b and Nitelink 39N serve Cabra Road, while 37,39, 39a,70, 70N serve Navan Road. Route 46A travels the North Circular Road, part of Cabras southern boundary, suburban rail stops in the rundown Broombridge railway station, en route to Maynooth. As part of the governments Transport 21 strategy, there are plans to extend the Luas, by linking the present red line to Dublin Airport, there would be stops at local areas like Liffey Junction and the new Dublin Institute of Technology campus at Grangegorman. The main Dublin to Cavan road, the N3, travels through Cabra, from about 1480, the manor of Cabra was held by a branch of the Plunket family, later ennobled as Earls of Fingall, whose main residence was Dunsoghly Castle near Finglas. There are three contiguous townlands called Cabra, each in a different civil parish, Castleknock, Glasnevin, the three met at the gate lodge of Cabragh House, which is today the situation of the roundabout at the junction of Ratoath Road and Drumcliffe Road. Cabragh House was located where the current Canon Burke Senior Citizens Flats complex stands, completed in 1598, it was first occupied by the Segrave family. The mansion was then the home of the hanging judge Lord Norbery until he died in 1831, charles Segrave, whose son was the famous racing driver Henry Segrave lived there until 1912. The big house was bought by Dublin Corporation by way of a purchase order in 1939 for the construction of local authority housing. Until the 1920s, when large housing developments took place. Many of the people who moved to the new suburb were from the city centre slums, the Industrial Revolution brought the construction of the Royal Canal in 1790 and the laying of the Dublin-Galway railway line of which both went through the heart of the area. From about 1880-1930, Cabra was a prominent market garden centre and a giant lairage, numerous footballers hail from Cabra, including Republic of Ireland international goalkeeper Wayne Henderson, and Eamonn Fagan and Liam Whelan, both from St. Attractas Road. Whelan was one of the Manchester United Busby Babes who died in the Munich air disaster of 1958, the former Leeds United and Irish player and manager Johnny Giles also hails from the area. Roddy Collins, former manager of Bohemians, Shamrock Rovers and Maltese side Floriana, one of the worlds most famous mathematicians, William Rowan Hamilton, who freed algebra from the commutative postulate of multiplication was associated with the area. There is a plaque in his honour at the Broom Bridge, Cabra West has many factories in the industrial park and also along Bannow Road, one of the most famous of these being the Batchelors beans factory. The Roman Catholic church of Christ the King was built during the following the Eucumenical Congress of 1932
10.
William Rowan Hamilton
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Sir William Rowan Hamilton PRIA FRSE was an Irish physicist, astronomer, and mathematician, who made important contributions to classical mechanics, optics, and algebra. His studies of mechanical and optical systems led him to discover new mathematical concepts and his best known contribution to mathematical physics is the reformulation of Newtonian mechanics, now called Hamiltonian mechanics. This work has proven central to the study of classical field theories such as electromagnetism. In pure mathematics, he is best known as the inventor of quaternions, Hamilton is said to have shown immense talent at a very early age. Astronomer Bishop Dr. John Brinkley remarked of the 18-year-old Hamilton, This young man, I do not say will be, but is, Hamilton also invented icosian calculus, which he used to investigate closed edge paths on a dodecahedron that visit each vertex exactly once. Hamilton was the fourth of nine born to Sarah Hutton and Archibald Hamilton. Hamiltons father, who was from Dunboyne, worked as a solicitor, by the age of three, Hamilton had been sent to live with his uncle James Hamilton, a graduate of Trinity College who ran a school in Talbots Castle in Trim, Co. His uncle soon discovered that Hamilton had an ability to learn languages. At the age of seven he had made very considerable progress in Hebrew. These included the classical and modern European languages, and Persian, Arabic, Hindustani, Sanskrit, in September 1813 the American calculating prodigy Zerah Colburn was being exhibited in Dublin. Colburn was 9, an older than Hamilton. The two were pitted against each other in a mental arithmetic contest with Colburn emerging the clear victor, in reaction to his defeat, Hamilton dedicated less time to studying languages and more time to studying mathematics. Hamilton was part of a small but well-regarded school of mathematicians associated with Trinity College, Dublin, which he entered at age 18. He studied both classics and mathematics, and was appointed Professor of Astronomy in 1827, prior to his taking up residence at Dunsink Observatory where he spent the rest of his life. Hamilton made important contributions to optics and to classical mechanics and his first discovery was in an early paper that he communicated in 1823 to Dr. Brinkley, who presented it under the title of Caustics in 1824 to the Royal Irish Academy. It was referred as usual to a committee, while their report acknowledged its novelty and value, they recommended further development and simplification before publication. Between 1825 and 1828 the paper grew to an immense size, but it also became more intelligible, and the features of the new method were now easily to be seen. Until this period Hamilton himself seems not to have fully understood either the nature or importance of optics and he proposed for it when he first predicted its existence in the third supplement to his Systems of Rays, read in 1832
11.
Quaternion
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In mathematics, the quaternions are a number system that extends the complex numbers. They were first described by Irish mathematician William Rowan Hamilton in 1843, a feature of quaternions is that multiplication of two quaternions is noncommutative. Hamilton defined a quaternion as the quotient of two directed lines in a space or equivalently as the quotient of two vectors. Quaternions are generally represented in the form, a + bi + cj + dk where a, b, c, and d are real numbers, and i, j, and k are the fundamental quaternion units. In practical applications, they can be used other methods, such as Euler angles and rotation matrices, or as an alternative to them. In modern mathematical language, quaternions form a four-dimensional associative normed division algebra over the real numbers, in fact, the quaternions were the first noncommutative division algebra to be discovered. The algebra of quaternions is often denoted by H, or in blackboard bold by H and it can also be given by the Clifford algebra classifications Cℓ0,2 ≅ Cℓ03,0. These rings are also Euclidean Hurwitz algebras, of which quaternions are the largest associative algebra. The unit quaternions can be thought of as a choice of a structure on the 3-sphere S3 that gives the group Spin. Quaternion algebra was introduced by Hamilton in 1843, carl Friedrich Gauss had also discovered quaternions in 1819, but this work was not published until 1900. Hamilton knew that the numbers could be interpreted as points in a plane. Points in space can be represented by their coordinates, which are triples of numbers, however, Hamilton had been stuck on the problem of multiplication and division for a long time. He could not figure out how to calculate the quotient of the coordinates of two points in space. The great breakthrough in quaternions finally came on Monday 16 October 1843 in Dublin, as he walked along the towpath of the Royal Canal with his wife, the concepts behind quaternions were taking shape in his mind. When the answer dawned on him, Hamilton could not resist the urge to carve the formula for the quaternions, i2 = j2 = k2 = ijk = −1, into the stone of Brougham Bridge as he paused on it. On the following day, Hamilton wrote a letter to his friend and fellow mathematician, John T. Graves and this letter was later published in the London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, vol. xxv, pp 489–95. In the letter, Hamilton states, And here there dawned on me the notion that we must admit, in some sense, an electric circuit seemed to close, and a spark flashed forth. Hamilton called a quadruple with these rules of multiplication a quaternion, Hamiltons treatment is more geometric than the modern approach, which emphasizes quaternions algebraic properties
12.
Cyanotype
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Cyanotype is a photographic printing process that produces a cyan-blue print. Engineers used the well into the 20th century as a simple and low-cost process to produce copies of drawings. The process uses two chemicals, ammonium iron citrate and potassium ferricyanide, the English scientist and astronomer Sir John Herschel discovered the procedure in 1842. Though the process was developed by Herschel, he considered it as mainly a means of reproducing notes and diagrams, by using this photogram process, Anna Atkins is sometimes considered the first female photographer. Numerous contemporary artists employ the process in their art, Christian Marclay, Marco Breuer, Kate Cordsen, Hugh Scott-Douglas. In a typical procedure, equal volumes of an 8. 1% solution of potassium ferricyanide, the overall contrast of the sensitizer solution can be increased with the addition of approximately 6 drops of 1% solution potassium dichromate for every 2 ml of sensitizer solution. This mildly photosensitive solution is applied to a receptive surface. Cyanotypes can be printed on any surface capable of soaking up the iron solution, although watercolor paper is a preferred medium, cotton, wool and even gelatin sizing on nonporous surfaces have been used. Care should be taken to avoid alkaline-buffered papers, which degrade the image over time, prints can be made from large format negatives and lithography film, Digital negative or everyday objects can be used to make photograms. A positive image can be produced by exposing it to a source of light as a contact print through the negative or objects. The combination of UV light and the citrate reduces the iron to iron and this is followed by a complex reaction of the iron complex with ferricyanide. The result is an insoluble, blue dye known as Prussian blue, the extent of color change depends on the amount of UV light, but acceptable results are usually obtained after 10–20 minute exposures on a dark, gloomy day. After exposure, developing of the picture involves the yellow unreacted iron solution being rinsed off with running water, although the blue color darkens upon drying, the effect can be accelerated by soaking the print in a 6% solution of 3% hydrogen peroxide. The water-soluble iron salts are washed away, while the non-water-soluble Prussian blue remains in the paper and this is what gives the picture its typical blue color. The highlight values should appear overexposed, as the water reduces the final print values. In a cyanotype, a blue is usually the color, however. These fall into three categories, reducing, intensifying, and toning, reducing is the process of reducing or decreasing the intensity of the blue. Sodium carbonate, ammonia, Clorox, TSP, borax, Dektol, a good easily obtained reducer is bleach
13.
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
14.
Anna Atkins
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Anna Atkins was an English botanist and photographer. She is often considered the first person to publish a book illustrated with photographic images, some sources claim that she was the first woman to create a photograph. Atkins was born in Tonbridge, Kent, England in 1799 and her mother Hester Anne Children didnt recover from the effects of childbirth and died in 1800. Anna became close to her father John George Children, Anna received an unusually scientific education for a woman of her time. Her detailed engravings of shells were used to illustrate her fathers translation of Lamarcks Genera of Shells, in 1825 she married John Pelly Atkins, a London West India merchant, and they moved to Halstead Place, the Atkins family home in Sevenoaks, Kent. Atkins pursued her interests in botany, for example by collecting dried plants and these were probably used as photograms later. John George Children and John Pelly Atkins were friends of William Henry Fox Talbot, Anna Atkins learned directly from Talbot about two of his inventions related to photography, the photogenic drawing technique and calotypes. Atkins was known to have had access to a camera by 1841, some sources claim that Atkins was the first female photographer. Other sources name Constance Talbot, the wife of William Fox Talbot, as no camera-based photographs by Anna Atkins nor any photographs by Constance Talbot survive, the issue may never be resolved. Sir John Herschel, a friend of Atkins and Children, invented the photographic process in 1842. Within a year, Atkins applied the process to algae by making cyanotype photograms that were printed by placing the unmounted dried-algae original directly on the cyanotype paper. Atkins self-published her photograms in the first installment of Photographs of British Algae, Atkins produced a total of three volumes of Photographs of British Algae, Cyanotype Impressions between 1843 and 1853. Only 17 copies of the book are known to exist, in states of completeness. The Linnean Society of London, whose copy lacks part 7 of volume 1, because of the books rarity and historical importance, it is quite expensive. One copy of the book with 411 plates in three volumes sold for £133,500 at auction in 1996, another copy with 382 prints in two volumes which was owned by scientist Robert Hunt sold for £229,250 at auction in 2004. In addition, she published books with non-photographic work and she died at Halstead Place in 1871 of paralysis, rheumatism, and exhaustion at the age of 72. By the author of The perils of fashion, memoir of J. C. Children, including some unpublished poetry by his father and himself. London, John Bowye Nichols and Sons, by the author of The colonel, etc
15.
Eta Carinae
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Previously a 4th-magnitude star, it brightened in 1837 to become brighter than Rigel marking the start of the Great Eruption. Eta Carinae became the second-brightest star in the sky between 11 and 14 March 1843 before fading well below naked eye visibility after 1856, in a smaller eruption, it reached 6th magnitude in 1892 before fading again. It has brightened consistently since about 1940, becoming brighter than magnitude 4.5 by 2014, Eta Carinae is circumpolar south of latitude 30°S, so it is never visible north of about latitude 30°N. The two main stars of the Eta Carinae system have an orbit with a period of 5.54 years. This is the star known to produce ultraviolet laser emission. The secondary star is hot and also highly luminous, probably of spectral class O, the system is heavily obscured by the Homunculus Nebula, material ejected from the primary during the Great Eruption. It is a member of the Trumpler 16 open cluster within the much larger Carina Nebula, although unrelated to the star or nebula, the weak Eta Carinids meteor shower has a radiant very close to Eta Carinae. Frederick de Houtmans independent star catalogue from 1603 does not include Eta Carinae among the other stars in the region. The earliest firm record was made by Edmond Halley in 1677 when he recorded the star simply as Sequens within a new constellation Robur Carolinum and his Catalogus Stellarum Australium was published in 1679. The star was known by the Bayer designations Eta Roboris Caroli. Eta fell within the portion of the ship which was later to become the constellation Carina. It was not generally known as Eta Carinae until 1879, when the stars of Argo Navis were finally given the epithets of the constellations in the Uranometria Argentina of Gould. Eta Carinae is too far south to be part of the mansion-based traditional Chinese astronomy, together with s Carinae, λ Centauri, and λ Muscae, Eta Carinae forms the asterism 海山. Eta Carinae has the names Tseen She and Foramen, Halley gave an approximate apparent magnitude of 4 at the time of discovery, which has been calculated as magnitude 3.3 on the modern scale. The handful of earlier sightings suggest that Eta Carinae was not significantly brighter than this for much of the 17th century. Further sporadic observations over the next 70 years show that Eta Carinae was probably around 3rd magnitude or fainter, in 1827 Burchell specifically noted Eta Carinaes unusual brightness at 1st magnitude, and was the first to suspect that it varied in brightness. John Herschel made a series of accurate measurements in the 1830s showing that Eta Carinae consistently shone around magnitude 1.4 until November 1837. On the evening of December 16,1837, Herschel was astonished to see that it had brightened to slightly outshine Rigel and this event marked the beginning of a roughly 18-year period known as the Great Eruption
16.
Great Comet of 1843
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The Great Comet of 1843, formally designated C/1843 D1 and 1843 I, was a long-period comet which became very bright in March 1843. It was discovered on February 5,1843 and rapidly brightened to become a great comet and it was a member of the Kreutz Sungrazers, a family of comets resulting from the breakup of a parent comet into multiple fragments in about 1106. These comets pass extremely close to the surface of the Sun—within a few solar radii—and often become very bright as a result and it was last observed on April 19,1843. At that time this comet had passed closer to the Sun than any known object. The Great Comet of 1843 developed a long tail during. At over two units in length, it was the longest known cometary tail until measurements in 1996 showed that Comet Hyakutakes tail was almost twice as long. There is a painting in the National Maritime Museum that was created by astronomer Charles Piazzi Smyth, the purpose of the painting is to show the overall brightness and size of the tail of the comet. Estimates for the period of the comet have varied from 512 ±105 years,654 ±103 years,688 years. But the comet was observed over a period of 45 days from March 5 to April 19. The Mexican composer Luis Baca composed a waltz for piano, El cometa de 1843 and it appeared as no. com Saw a comet star ablazing
17.
Sunspot
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Sunspots are temporary phenomena on the photosphere of the Sun that appear as dark spots compared with surrounding regions. They are areas of reduced surface temperature caused by concentrations of field flux that inhibit convection. Sunspots usually appear in pairs of magnetic polarity. Their number varies according to the approximately 11-year solar cycle, individual sunspots may endure anywhere from a few days to a few months, but eventually decay. Sunspots expand and contract as they move across the surface of the Sun with sizes ranging from 16 kilometers to 160,000 kilometers in diameter, the larger variety are visible from Earth without the aid of a telescope. They may travel at speeds, or proper motions of a few hundred meters per second when they first emerge. Indicating intense magnetic activity, sunspots accompany secondary phenomena such as coronal loops, most solar flares and coronal mass ejections originate in magnetically active regions around visible sunspot groupings. Similar phenomena indirectly observed on other than the sun are commonly called starspots. Although they are at temperatures of roughly 3, 000–4,500 K, isolated from the surrounding photosphere a sunspot would be brighter than the Moon. If the stress on the tubes reaches a limit, they curl up. Convection is inhibited at the points, the energy flux from the Suns interior decreases. The Wilson effect implies that sunspots are depressions on the Suns surface, observations using the Zeeman effect show that prototypical sunspots come in pairs with opposite magnetic polarity. From cycle to cycle, the polarities of leading and trailing sunspots change from north/south to south/north, magnetic pressure should tend to remove field concentrations, causing the sunspots to disperse, but sunspot lifetimes are measured in days to weeks. Sunspot activity cycles about every eleven years, the point of highest sunspot activity during a cycle is known as solar maximum, and the point of lowest activity as solar minimum. This period is observed in most other solar activity and is linked to a variation in the solar magnetic field that changes polarity with this period. Early in the cycle, sunspots appear in the latitudes and then move towards the equator as the cycle approaches maximum. Spots from two adjacent cycles can co-exist for some time, spots from adjacent cycles can be distinguished by direction of their magnetic field. The Wolf number sunspot index counts the number of sunspots
18.
Jean-Baptiste Dumas
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He also developed a method for the analysis of nitrogen in compounds. Dumas was born in Alès, and became an apprentice to an apothecary in his native town. In 1822, he moved to Paris, acting on the advice of Alexander von Humboldt and he was one of the founders of the École centrale des arts et manufactures in 1829. In 1832 Dumas became a member of the French Academy of Sciences, from 1868 until his death in 1884 he would serve the academy as the permanent secretary for its department of Physical Sciences. In 1838, Dumas was elected a member of the Royal Swedish Academy of Sciences. The same year he became correspondent of the Royal Institute of the Netherlands and, Dumas was president of Société dencouragement pour lindustrie nationale from 1845 to 1864. After 1848, he exchanged much of his work for ministerial posts under Napoléon III. He became a member of the National Legislative Assembly, Dumas was a devout Catholic who would often defend Christian views against critics. Dumas died at Cannes in 1884, and is buried at the Montparnasse Cemetery in Paris and his is one of the 72 names inscribed on the Eiffel tower. The classification of compounds into homologous series was advanced as one consequence of his researches into the acids generated by the oxidation of the alcohols. Dumas also showed that kidneys remove urea from the blood, vapour Densities and Atomic Masses Dumas perfected the method of measuring vapor densities which was also important in determining atomic weights. A known amount of the substance being analyzed was put into a previously weighed glass bulb, the pressure was recorded with a barometer, and the bulb is allowed to cool to determine the mass of the vapor. The universal gas law was used to determine the moles of gas within the bulb. He showed in all elastic fluids observed under the same conditions, Dumas established new values for the atomic mass of thirty elements, setting the value for hydrogen to 1. Determination of Nitrogen In 1833, Dumas developed a method for estimating the amount of nitrogen in an organic compound and he made important revisions to the existing combustion methods with a sophisticated pneumatic trough. These revisions were the flushing of the tube with carbon dioxide. Flushing with carbon dioxide eliminated the nitrogen present in the air that previously occupied the combustion tube, the potassium hydroxide dissolved the passing carbon dioxide gas, which left nitrogen as the only gas in the collection tube. Theory of Substitution and Theory of Chemical Types At the Tuileries palace in Paris, Alexandre Brongniart asked his son-in-law, Dumas, to investigate
19.
Lactose
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Lactose is a disaccharide sugar composed of galactose and glucose that is found in milk. Lactose makes up around 2–8% of milk, although the amount varies among species and individuals and it is extracted from sweet or sour whey. The name comes from lac, the Latin word for milk and it has a formula of C12H22O11 and the hydrate formula C12H22O11·H2O, making it an isomer of sucrose. The first crude isolation of lactose, by Italian physician Fabrizio Bartoletti, was published in 1633, in 1700, the Venetian pharmacist Lodovico Testi published a booklet of testimonials to the power of milk sugar to relieve, among other ailments, the symptoms of arthritis. In 1715, Testis procedure for making milk sugar was published by Antonio Vallisneri, lactose was identified as a sugar in 1780 by Carl Wilhelm Scheele. In 1812, Heinrich Vogel recognized that glucose was a product of hydrolyzing lactose, in 1856, Louis Pasteur crystallized the other component of lactose, galactose. By 1894, Emil Fischer had established the configurations of the component sugars, lactose was named by the French chemist Jean Baptiste André Dumas in 1843. Lactose is a derived from the condensation of galactose and glucose. Lactose is hydrolysed to glucose and galactose, isomerised in alkaline solution to lactulose, lactose monohydrate crystals have a characteristic tomahawk shape that can be observed with a light microscope. Several million tons are produced annually as a by-product of the dairy industry, whey is made up of 6. 5% solids of which 4. 8% is lactose that may be purified by crystallisation. Whey or milk plasma is the liquid remaining after milk is curdled and strained, lactose makes up about 2–8% of milk by weight. Industrially, lactose is produced from whey permeate – that is whey filtrated for all major proteins, the protein fraction is used in infant nutrition and sport nutrition while the permeate can be evaporated to 60–65% solids and crystallized while cooling. Lactose can also be precipitated from whey using ethanol, since it is insoluble in ethanol, lactose precipitates, in about 65% yield. Infant mammals nurse on their mothers to drink milk, which is rich in lactose, the intestinal villi secrete the enzyme called lactase to digest it. This enzyme cleaves the molecule into its two subunits, the simple sugars glucose and galactose, which can be absorbed. Since lactose occurs mostly in milk, in most mammals, the production of lactase gradually decreases with maturity due to a lack of continuing consumption. Many people with ancestry in Europe, West Asia, South Asia, the Sahel belt in West Africa, East Africa, in many of these areas, milk from mammals such as cattle, goats, and sheep is used as a large source of food. Hence, it was in these regions that genes for lifelong lactase production first evolved, the genes of adult lactose tolerance have evolved independently in various ethnic groups
20.
Carl Gustaf Mosander
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Carl Gustaf Mosander was a Swedish chemist. He discovered the elements lanthanum, erbium and terbium, born in Kalmar, Mosander attended school there until he moved to Stockholm with his mother at age 12. In Stockholm, he became an apprentice at the Ugglan pharmacy and he took his pharmacy examination in 1817, but had an interest in medicine and matriculated as a student in the Karolinska Institute in 1820 and graduated with his Master of Surgery degree in 1824. Mosander worked teaching chemistry at the Institute and as an assistant in the collection of the Swedish Museum of Natural History. In 1836 he succeeded his professor of chemistry during his studies, Jöns Jakob Berzelius, as professor of chemistry. Mosander discovered lanthanum in 1839 when he partially decomposed a sample of cerium nitrate by heating and treating the resulting salt with dilute nitric acid, in 1843 he discovered terbium and erbium. Mosander was elected a member of the Royal Swedish Academy of Sciences in 1833 and he died in Lovön, Stockholm County, at age 61. The discovery of the elements, XVI
21.
Terbium
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Terbium is a chemical element with symbol Tb and atomic number 65. It is a silvery-white, rare metal that is malleable, ductile. The ninth member of the series, terbium is a fairly electropositive metal that reacts with water. Terbium is never found in nature as an element, but it is contained in many minerals, including cerite, gadolinite, monazite, xenotime. Swedish chemist Carl Gustaf Mosander discovered terbium as a separate elemental compound in 1843 and he detected it as an impurity in yttrium oxide, Y2O3. Yttrium and terbium are named after the village of Ytterby in Sweden, Terbium was not isolated in pure form until the advent of ion exchange techniques. As a component of Terfenol-D, terbium is of use in actuators, in sonar systems. Most of the worlds supply is used in green phosphors. Terbium oxide is in fluorescent lamps and TV tubes, Terbium is a silvery-white rare earth metal that is malleable, ductile and soft enough to be cut with a knife. It is relatively stable in air compared to the earlier, more reactive lanthanides in the first half of the lanthanide series, Terbium exists in two crystal allotropes with a transformation temperature of 1289 °C between them. The terbium cation is brilliantly fluorescent, in a bright color that is the result of a strong green emission line in combination with other lines in the orange. The yttrofluorite variety of the mineral fluorite owes its creamy-yellow fluorescence in part to terbium, Terbium easily oxidizes, and is therefore used in its elemental form specifically for research. Single terbium atoms have been isolated by implanting them into fullerene molecules, Terbium has a simple ferromagnetic ordering at temperatures below 219 K. This unusual antiferromagnetism transforms into a disordered state at 230 K. The most common state of terbium is +3, as in Tb 2O3. The +4 state is known in TbO2 and TbF4, Terbium burns readily to form a mixed terbium oxide,8 Tb +7 O2 →2 Tb4O7 In solution, terbium forms only trivalent ions. In those compounds, Tb mostly exhibits the oxidation states +3, Terbium halogenides are obtained by annealing Tb halogenides in presence of metallic Tb in tantalum containers. Terbium also forms sesquichloride Tb2Cl3, which can be reduced to TbCl by annealing at 800 °C
22.
Erbium
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Erbium is a chemical element in the lanthanide series, with symbol Er and atomic number 68. A silvery-white solid metal when artificially isolated, natural erbium is always found in combination with other elements on Earth. As such, it is a rare earth element which is associated with other rare elements in the mineral gadolinite from Ytterby in Sweden, which yttrium, ytterbium. Erbiums principal uses involve its pink-colored Er3+ ions, which have optical fluorescent properties particularly useful in laser applications. Erbium-doped glasses or crystals can be used as optical amplification media and this process results in an unusually mechanically simple laser optical amplifier for signals transmitted by fiber optics. The 1550 nm wavelength is especially important for optical communications because standard single mode optical fibers have minimal loss at this particular wavelength. Such shallow tissue deposition of energy is helpful in laser surgery. A trivalent element, pure erbium metal is malleable, soft yet stable in air and its salts are rose-colored, and the element has characteristic sharp absorption spectra bands in visible light, ultraviolet, and near infrared. Otherwise it looks much like the rare earths. Erbiums properties are to a degree dictated by the kind and amount of impurities present, Erbium does not play any known biological role, but is thought to be able to stimulate metabolism. Those clusters can be isolated by encapsulating them into fullerene molecules, all of the remaining radioactive isotopes have half-lives that are less than 3.5 h, and the majority of these have half-lives that are less than 4 minutes. This element also has 13 meta states, with the most stable being 167mEr with a half-life of 2.269 s, the isotopes of erbium range in atomic weight from 142.9663 u to 176.9541 u. The primary decay mode before the most abundant stable isotope, 166Er, is electron capture, the primary decay products before 166Er are element 67 isotopes, and the primary products after are element 69 isotopes. Erbium was discovered by Carl Gustaf Mosander in 1843, Mosander was working with a sample of what was thought to be the single metal oxide yttria, derived from the mineral gadolinite. He discovered that the sample contained at least two metal oxides in addition to pure yttria, which he named erbia and terbia after the village of Ytterby where the gadolinite had been found, Mosander was not certain of the purity of the oxides and later tests confirmed his uncertainty. Erbia and terbia, however, were confused at this time, a spectroscopist mistakenly switched the names of the two elements during spectroscopy. After 1860, terbia was renamed erbia and after 1877 what had been known as erbia was renamed terbia, fairly pure Er2O3 was independently isolated in 1905 by Georges Urbain and Charles James. Reasonably pure metal wasnt produced until 1934 when Klemm and Bommer reduced the chloride with potassium vapor
23.
Kinetic theory of gases
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Kinetic theory explains macroscopic properties of gases, such as pressure, temperature, viscosity, thermal conductivity, and volume, by considering their molecular composition and motion. The theory posits that gas pressure is due to the impacts, on the walls of a container, Kinetic theory defines temperature in its own way, not identical with the thermodynamic definition. Under a microscope, the making up a liquid are too small to be visible. Known as Brownian motion, it directly from collisions between the grains or particles and liquid molecules. As analyzed by Albert Einstein in 1907, this evidence for kinetic theory is generally seen as having confirmed the concrete material existence of atoms. The theory for ideal gases makes the assumptions, The gas consists of very small particles known as molecules. This smallness of their size is such that the volume of the individual gas molecules added up is negligible compared to the volume of the smallest open ball containing all the molecules. This is equivalent to stating that the distance separating the gas particles is large compared to their size. These particles have the same mass, the number of molecules is so large that statistical treatment can be applied. These molecules are in constant, random, and rapid motion, the rapidly moving particles constantly collide among themselves and with the walls of the container. All these collisions are perfectly elastic and this means, the molecules are considered to be perfectly spherical in shape, and elastic in nature. Except during collisions, the interactions among molecules are negligible and this means that the inter-particle distance is much larger than the thermal de Broglie wavelength and the molecules are treated as classical objects. Because of the two, their dynamics can be treated classically. This means that the equations of motion of the molecules are time-reversible, the average kinetic energy of the gas particles depends only on the absolute temperature of the system. The kinetic theory has its own definition of temperature, not identical with the thermodynamic definition, the elapsed time of a collision between a molecule and the containers wall is negligible when compared to the time between successive collisions. Because they have mass, the gas molecules will be affected by gravity, more modern developments relax these assumptions and are based on the Boltzmann equation. These can accurately describe the properties of gases, because they include the volume of the molecules. The necessary assumptions are the absence of quantum effects, molecular chaos, expansions to higher orders in the density are known as virial expansions
24.
Luigi Federico Menabrea
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Luigi Federico Menabrea, later made Count Menabrea and Marquis of Valdora, was an Italian general, statesman and mathematician who served as the Prime Minister of Italy from 1867 to 1869. Menabrea was born at Chambéry, then part of the Kingdom of Sardinia and he was educated at the University of Turin, where he qualified as an engineer and became a doctor of mathematics. As an officer of engineers he replaced Cavour in 1831 at the fortress of Bard and he then became professor of mechanics and construction at the military academy and at the university of Turin. King Charles Albert sent him in 1848 on diplomatic missions to secure the adhesion of Modena and he entered the Piedmontese parliament, and was attached successively to the Ministries of War and Foreign Affairs. He belonged to the centre, and until the events of 1859 he believed in the possibility of a compromise between the Vatican and the state. He was major-general and commander-in-chief of the engineers in the Lombard campaign of 1859 and he superintended the siege works against Peschiera, was present at Palestro and Solferino, and repaired the fortifications of some of the northern fortresses. In 1860 he became lieutenant-general and conducted the siege of Gaeta and he was appointed senator and received the title of count. Entering the Ricasoli cabinet of 1861 as minister for the navy, he held the portfolio of public works until 1864 in the succeeding Farini and Minghetti cabinets. After the war of 1866, he was chosen as Italian plenipotentiary for the negotiation of the Treaty of Prague, on the eve of the assembly of the Oecumenical Council at Rome Menabrea reserved to the Italian government its right in respect of any measures directed against Italian institutions. He withdrew from seminary students in 1860 the exemption from military service which they had hitherto enjoyed, after a series of changes in the cabinet, and many crises, Menabrea resigned in December 1869 on the election of a new chamber in which he did not command a majority. He was made marquis of Valdora in 1875, ten years later he withdrew from public life, and died at Saint Capin on 24 May 1896. Sketch of the Analytical Engine Invented by Charles Babbage, Esq. with notes by trans, ada Lovelace, in Scientific Memoirs, Vol 3 OConnor, John J. Robertson, Edmund F. Luigi Federico Menabrea, MacTutor History of Mathematics archive, University of St Andrews. This article incorporates text from a now in the public domain, Chisholm, Hugh
25.
Charles Babbage
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Charles Babbage KH FRS was an English polymath. A mathematician, philosopher, inventor and mechanical engineer, Babbage is best remembered for originating the concept of a programmable computer. His varied work in other fields has led him to be described as pre-eminent among the many polymaths of his century, parts of Babbages uncompleted mechanisms are on display in the Science Museum in London. In 1991, a perfectly functioning difference engine was constructed from Babbages original plans, built to tolerances achievable in the 19th century, the success of the finished engine indicated that Babbages machine would have worked. Babbages birthplace is disputed, but according to the Oxford Dictionary of National Biography he was most likely born at 44 Crosby Row, Walworth Road, London, a blue plaque on the junction of Larcom Street and Walworth Road commemorates the event. His date of birth was given in his obituary in The Times as 26 December 1792, the parish register of St. Marys Newington, London, shows that Babbage was baptised on 6 January 1792, supporting a birth year of 1791. Babbage was one of four children of Benjamin Babbage and Betsy Plumleigh Teape and his father was a banking partner of William Praed in founding Praeds & Co. of Fleet Street, London, in 1801. In 1808, the Babbage family moved into the old Rowdens house in East Teignmouth, around the age of eight, Babbage was sent to a country school in Alphington near Exeter to recover from a life-threatening fever. For a short time he attended King Edward VI Grammar School in Totnes, South Devon, Babbage then joined the 30-student Holmwood academy, in Baker Street, Enfield, Middlesex, under the Reverend Stephen Freeman. The academy had a library that prompted Babbages love of mathematics and he studied with two more private tutors after leaving the academy. The first was a clergyman near Cambridge, through him Babbage encountered Charles Simeon and his evangelical followers and he was brought home, to study at the Totnes school, this was at age 16 or 17. The second was an Oxford tutor, under whom Babbage reached a level in Classics sufficient to be accepted by Cambridge, Babbage arrived at Trinity College, Cambridge, in October 1810. He was already self-taught in some parts of mathematics, he had read in Robert Woodhouse, Joseph Louis Lagrange. As a result, he was disappointed in the standard mathematical instruction available at the university, Babbage, John Herschel, George Peacock, and several other friends formed the Analytical Society in 1812, they were also close to Edward Ryan. In 1812 Babbage transferred to Peterhouse, Cambridge and he was the top mathematician there, but did not graduate with honours. He instead received a degree without examination in 1814 and he had defended a thesis that was considered blasphemous in the preliminary public disputation, but it is not known whether this fact is related to his not sitting the examination. Considering his reputation, Babbage quickly made progress and he lectured to the Royal Institution on astronomy in 1815, and was elected a Fellow of the Royal Society in 1816. After graduation, on the hand, he applied for positions unsuccessfully
26.
Analytical Engine
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The Analytical Engine was a proposed mechanical general-purpose computer designed by English mathematician and computer pioneer Charles Babbage. It was first described in 1837 as the successor to Babbages difference engine, in other words, the logical structure of the Analytical Engine was essentially the same as that which has dominated computer design in the electronic era. Babbage was never able to complete construction of any of his machines due to conflicts with his chief engineer and it was not until the 1940s that the first general-purpose computers were actually built, more than a century after Babbage had proposed the pioneering Analytical Engine in 1837. Construction of this machine was never completed, Babbage had conflicts with his engineer, Joseph Clement. During this project, he realized that a more general design. The work on the design of the Analytical Engine started in 1835, the input, consisting of programs and data was to be provided to the machine via punched cards, a method being used at the time to direct mechanical looms such as the Jacquard loom. For output, the machine would have a printer, a curve plotter, the machine would also be able to punch numbers onto cards to be read in later. It employed ordinary base-10 fixed-point arithmetic, there was to be a store capable of holding 1,000 numbers of 40 decimal digits each. An arithmetical unit would be able to all four arithmetic operations, plus comparisons. Initially it was conceived as a difference engine curved back upon itself, in a circular layout. Later drawings depict a regularized grid layout, the programming language to be employed by users was akin to modern day assembly languages. Loops and conditional branching were possible, and so the language as conceived would have been Turing-complete as later defined by Alan Turing, there were three separate readers for the three types of cards. Babbage developed some two dozen programs for the Analytical Engine between 1837 and 1840, and one program later and these programs treat polynomials, iterative formulas, Gaussian elimination, and Bernoulli numbers. In 1842, the Italian mathematician Luigi Federico Menabrea published a description of the based on a lecture by Babbage in French. In 1843, the description was translated into English and extensively annotated by Ada Lovelace, in recognition of her additions to Menabreas paper, which included a way to calculate Bernoulli numbers using the machine, she has been described as the first computer programmer. Late in his life, Babbage sought ways to build a version of the machine. In 1878, a committee of the British Association for the Advancement of Science described the Analytical Engine as a marvel of mechanical ingenuity, but recommended against constructing it. The committee acknowledged the usefulness and value of the machine, but could not estimate the cost of building it, and were unsure whether the machine would function correctly after being built
27.
Algorithm
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In mathematics and computer science, an algorithm is a self-contained sequence of actions to be performed. Algorithms can perform calculation, data processing and automated reasoning tasks, an algorithm is an effective method that can be expressed within a finite amount of space and time and in a well-defined formal language for calculating a function. The transition from one state to the next is not necessarily deterministic, some algorithms, known as randomized algorithms, giving a formal definition of algorithms, corresponding to the intuitive notion, remains a challenging problem. In English, it was first used in about 1230 and then by Chaucer in 1391, English adopted the French term, but it wasnt until the late 19th century that algorithm took on the meaning that it has in modern English. Another early use of the word is from 1240, in a manual titled Carmen de Algorismo composed by Alexandre de Villedieu and it begins thus, Haec algorismus ars praesens dicitur, in qua / Talibus Indorum fruimur bis quinque figuris. Which translates as, Algorism is the art by which at present we use those Indian figures, the poem is a few hundred lines long and summarizes the art of calculating with the new style of Indian dice, or Talibus Indorum, or Hindu numerals. An informal definition could be a set of rules that precisely defines a sequence of operations, which would include all computer programs, including programs that do not perform numeric calculations. Generally, a program is only an algorithm if it stops eventually, but humans can do something equally useful, in the case of certain enumerably infinite sets, They can give explicit instructions for determining the nth member of the set, for arbitrary finite n. An enumerably infinite set is one whose elements can be put into one-to-one correspondence with the integers, the concept of algorithm is also used to define the notion of decidability. That notion is central for explaining how formal systems come into being starting from a set of axioms. In logic, the time that an algorithm requires to complete cannot be measured, from such uncertainties, that characterize ongoing work, stems the unavailability of a definition of algorithm that suits both concrete and abstract usage of the term. Algorithms are essential to the way computers process data, thus, an algorithm can be considered to be any sequence of operations that can be simulated by a Turing-complete system. Although this may seem extreme, the arguments, in its favor are hard to refute. Gurevich. Turings informal argument in favor of his thesis justifies a stronger thesis, according to Savage, an algorithm is a computational process defined by a Turing machine. Typically, when an algorithm is associated with processing information, data can be read from a source, written to an output device. Stored data are regarded as part of the state of the entity performing the algorithm. In practice, the state is stored in one or more data structures, for some such computational process, the algorithm must be rigorously defined, specified in the way it applies in all possible circumstances that could arise. That is, any conditional steps must be dealt with, case-by-case
