|
John Dolland
John Dollond (30 November 1761) was an English optician, known for his successful optics business and his patenting and commercialization of achromatic doublets. Biography Dollond was the son of a Huguenot refugee, a silk-weaver at Spitalfields, London, where he was born. He followed his father's trade, but found time to acquire a knowledge of Latin, Greek, mathematics, physics, anatomy and other subjects. In 1752 he abandoned silk-weaving and joined his eldest son, Peter Dollond (1731–1820), who in 1750 had started in business as a maker of optical instruments; this business went on to become Dollond & Aitchison. His reputation grew rapidly, and in 1761 he was appointed optician to the king. In 1758 he published an "Account of some experiments concerning the different refrangibility of light", describing the experiments that led him to the achievement with which his name is specially associated, the discovery of a means of constructing achromatic lenses by the combination ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benjamin Wilson (painter)
Benjamin Wilson (21 June 1721 – 6 June 1788) was a British painter, printmaker and scientist (natural philosopher). Life He was the 14th child of Major Wilson, a wealthy York clothier whose house was decorated by the French history painter, Jacques Parmentier (d 1730). His father's business failed and Wilson moved to London, where he became a legal clerk and began to study painting, with the encouragement of William Hogarth, taking life-drawing classes at St. Martin's Lane Academy. For two weeks in 1746 and again from 1748 to 1750 he was in Dublin, where he practised successfully as a Portrait, portrait painter and electrical scientist. On his return to London he settled into Godfrey Kneller's old house in Great Queen Street and built up a lucrative portrait practice, competing with the young Joshua Reynolds. He obtained an introduction to Prince Edward, Duke of York and Albany (1739–67), who favoured him in numerous ways, possibly through one of his sitters, Sir John Savile, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Achromatic Lens
An achromatic lens or achromat is a lens (optics), lens that is designed to limit the effects of chromatic aberration, chromatic and spherical aberration. Achromatic lenses are corrected to bring two wavelengths (typically red and blue) into focus on the same plane. Wavelengths in between these two then have better focus error than could be obtained with a simple lens. The most common type of achromat is the achromatic doublet, which is composed of two individual lenses made from glasses with different amounts of Dispersion (optics), dispersion. Typically, one element is a negative (Lens (optics)#Types of simple lenses, concave) element made out of flint glass such as F2, which has relatively high dispersion, and the other is a positive (Lens (optics)#Types of simple lenses, convex) element made of Crown glass (optics), crown glass such as BK7, which has lower dispersion. The lens elements are mounted next to each other, often cemented together, and shaped so that the chromati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Achromatic Doublet
An achromatic lens or achromat is a lens that is designed to limit the effects of chromatic and spherical aberration. Achromatic lenses are corrected to bring two wavelengths (typically red and blue) into focus on the same plane. Wavelengths in between these two then have better focus error than could be obtained with a simple lens. The most common type of achromat is the achromatic doublet, which is composed of two individual lenses made from glasses with different amounts of dispersion. Typically, one element is a negative (concave) element made out of flint glass such as F2, which has relatively high dispersion, and the other is a positive (convex) element made of crown glass such as BK7, which has lower dispersion. The lens elements are mounted next to each other, often cemented together, and shaped so that the chromatic aberration of one is counterbalanced by that of the other. In the most common type (shown), the positive power of the crown lens element is not quite e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jesse Ramsden
Jesse Ramsden Fellow of the Royal Society, FRS FRSE (6 October 1735 – 5 November 1800) was a British mathematician, astronomy, astronomical and scientific instrument maker. His reputation was built on the engraving and design of dividing engines which allowed high accuracy measurements of angles and lengths in instruments. He produced instruments for astronomy that were especially well known for maritime use where they were needed for the measurement of latitudes and for his surveying instruments which were widely used for cartography and land survey both across the British Empire and outside. An achromatic eyepiece that he invented for telescopes and microscopes continues to be known as the Ramsden eyepiece. Life Ramsden was born at Salterhebble, Halifax, West Yorkshire, Halifax, West Riding of Yorkshire, England the son of Thomas Ramsden, an innkeeper and his wife Abigail née Flather. Having attended the free school at Halifax from 1744 to 1747, he was sent at the age of twe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apoplexy
Apoplexy () refers to the rupture of an internal organ and the associated symptoms. Informally or metaphorically, the term ''apoplexy'' is associated with being furious, especially as "apoplectic". Historically, it described what is now known as a hemorrhagic stroke, typically involving a ruptured blood vessel in the brain; modern medicine typically specifies the anatomical location of the bleeding, such as cerebral apoplexy, ovarian apoplexy, or pituitary apoplexy. Historical meaning From the late 14th to the late 19th century, the diagnosis ''apoplexy'' referred to any sudden death that began with abrupt loss of consciousness, especially when the victim died within seconds after losing consciousness. The word ''apoplexy'' was sometimes used to refer to the symptom of sudden loss of consciousness immediately preceding death. Strokes, ruptured aortic aneurysms, and even heart attacks were referred to as apoplexy in the past, because before the advent of biomedical scienc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
George III
George III (George William Frederick; 4 June 173829 January 1820) was King of Great Britain and King of Ireland, Ireland from 25 October 1760 until his death in 1820. The Acts of Union 1800 unified Kingdom of Great Britain, Great Britain and Kingdom of Ireland, Ireland into the United Kingdom of Great Britain and Ireland, with George as its king. He was concurrently Duke and Prince-elector of Electorate of Hanover, Hanover in the Holy Roman Empire before becoming King of Hanover on 12 October 1814. He was the first monarch of the House of Hanover who was born in Great Britain, spoke English as his first language, and never visited Hanover. George was born during the reign of his paternal grandfather, George II of Great Britain, King George II, as the first son of Frederick, Prince of Wales, and Princess Augusta of Saxe-Gotha. Following his father's death in 1751, Prince George became heir apparent and Prince of Wales. He succeeded to the throne on George II's death in 1760. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Society
The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, recognising excellence in science, supporting outstanding science, providing scientific advice for policy, education and public engagement and fostering international and global co-operation. Founded on 28 November 1660, it was granted a royal charter by Charles II of England, King Charles II and is the oldest continuously existing scientific academy in the world. The society is governed by its Council, which is chaired by the society's 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 basic members of the society, who are themselves elected by existing Fellows. , there are about 1,700 fellows, allowed to use the postnominal title FRS (Fellow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
History Of Telescopes
The history of the telescope can be traced to before the invention of the earliest known telescope, which appeared in 1608 in the Netherlands, when a patent was submitted by Hans Lippershey, an eyeglass maker. Although Lippershey did not receive his patent, news of the invention soon spread across Europe. The design of these early refracting telescopes consisted of a convex objective lens and a concave eyepiece. Galileo improved on this design the following year and applied it to astronomy. In 1611, Johannes Kepler described how a far more useful telescope could be made with a convex objective lens and a convex eyepiece lens. By 1655, astronomers such as Christiaan Huygens were building powerful but unwieldy Keplerian telescopes with compound eyepieces. Isaac Newton is credited with building the first reflector in 1668 with a design that incorporated a small flat diagonal mirror to reflect the light to an eyepiece mounted on the side of the telescope. Laurent Cassegrain in 167 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Samuel Klingenstierna
Samuel Klingenstierna (18 August 1698 – 26 October 1765) was a Swedish mathematician and scientist. He started his career as a lawyer but soon moved to natural philosophy. As a student he gave lectures on the then novel mathematical analysis of Newton and Leibniz. Klingenstierna was a professor of geometry at Uppsala University from 1728. In 1750 he moved to physics but retired two years later to become an advisor to the Commander of Artillery. In 1756 he assumed the post of the tutor of the Crown Prince, the future king Gustav III. He was the first to enunciate errors in Newton's theories of refraction, geometrical notes that John Dollond used in his experiments. Later on he was instrumental in the invention of the Achromatic Telescope The achromatic telescope is a refracting telescope that uses an achromatic lens to correct for chromatic aberration. How it works When an image passes through a lens, the light is refracted at different angles for different wavelengths. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isaac Newton
Sir Isaac Newton () was an English polymath active as a mathematician, physicist, astronomer, alchemist, theologian, and author. Newton was a key figure in the Scientific Revolution and the Age of Enlightenment, Enlightenment that followed. His book (''Mathematical Principles of Natural Philosophy''), first published in 1687, achieved the Unification of theories in physics#Unification of gravity and astronomy, first great unification in physics and established classical mechanics. Newton also made seminal contributions to optics, and Leibniz–Newton calculus controversy, shares credit with German mathematician Gottfried Wilhelm Leibniz for formulating calculus, infinitesimal calculus, though he developed calculus years before Leibniz. Newton contributed to and refined the scientific method, and his work is considered the most influential in bringing forth modern science. In the , Newton formulated the Newton's laws of motion, laws of motion and Newton's law of universal g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leonhard Euler
Leonhard Euler ( ; ; ; 15 April 170718 September 1783) was a Swiss polymath who was active as a mathematician, physicist, astronomer, logician, geographer, and engineer. He founded the studies of graph theory and topology and made influential discoveries in many other branches of mathematics, such as analytic number theory, complex analysis, and infinitesimal calculus. He also introduced much of modern mathematical terminology and Mathematical notation, notation, including the notion of a mathematical function. He is known for his work in mechanics, fluid dynamics, optics, astronomy, and music theory. Euler has been called a "universal genius" who "was fully equipped with almost unlimited powers of imagination, intellectual gifts and extraordinary memory". He spent most of his adult life in Saint Petersburg, Russia, and in Berlin, then the capital of Kingdom of Prussia, Prussia. Euler is credited for popularizing the Greek letter \pi (lowercase Pi (letter), pi) to denote Pi, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
