|
1720 In Science
The year 1720 in science and technology involved some significant events. Astronomy * February 10 – Edmond Halley is appointed as Astronomer Royal of England. Medicine * May – First patient admitted to the Westminster Public Infirmary, predecessor of St George's Hospital, London. * Dr Steevens' Hospital is established at Kilmainham, Dublin. * Great Plague of Marseille, the last major outbreak of bubonic plague in Europe. Physics * Willem 's Gravesande publishes ''Physices elementa mathematica, experimentis confirmata, sive introductio ad philosophiam Newtonianam'', an introduction to Newtonian physics, in Leiden. Technology * A theodolite is developed by Jonathan Sisson of England. * Pinchbeck is invented by English watchmaker Christopher Pinchbeck; it is an alloy of 83% copper and 17% zinc, creating a strong, hard-wearing metal which has the appearance and weight of 20 carat gold. * An early chronograph is invented which has only mechanical parts in it. * Henry de Saum ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Science
Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earliest archeological evidence for scientific reasoning is tens of thousands of years old. The earliest written records in the history of science come from Ancient Egypt and Mesopotamia in around 3000 to 1200 BCE. Their contributions to mathematics, astronomy, and medicine entered and shaped Greek natural philosophy of classical antiquity, whereby formal attempts were made to provide explanations of events in the physical world based on natural causes. After the fall of the Western Roman Empire, knowledge of Greek conceptions of the world deteriorated in Western Europe during the early centuries (400 to 1000 CE) of the Middle Ages, but was preserved in the Muslim world during the Islamic Golden Age and later by the efforts of Byzantine Greek scholars who brought Greek ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
English People
The English people are an ethnic group and nation native to England, who speak the English language in England, English language, a West Germanic languages, West Germanic language, and share a common history and culture. The English identity is of History of Anglo-Saxon England, Anglo-Saxon origin, when they were known in Old English as the ('race or tribe of the Angles'). Their ethnonym is derived from the Angles, one of the Germanic peoples who migrated to Great Britain around the 5th century AD. The English largely descend from two main historical population groups the West Germanic tribes (the Angles, Saxons, Jutes and Frisians) who settled in southern Britain following the withdrawal of the Ancient Rome, Romans, and the Romano-British culture, partially Romanised Celtic Britons already living there.Martiniano, R., Caffell, A., Holst, M. et al. Genomic signals of migration and continuity in Britain before the Anglo-Saxons. Nat Commun 7, 10326 (2016). https://doi.org/10 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Differential Gear
A differential is a gear train with three drive shafts that has the property that the rotational speed of one shaft is the average of the speeds of the others, or a fixed multiple of that average. Functional description The following description of a differential applies to a traditional rear-wheel-drive car or truck with an open or limited slip differential combined with a reduction gearset using bevel gears (these are not strictly necessary; see spur-gear differential): Thus, for example, if the car is making a turn to the right, the main ring gear may make 10 full rotations. During that time, the left wheel will make more rotations because it has farther to travel, and the right wheel will make fewer rotations as it has less distance to travel. The sun gears (which drive the axle half-shafts) will rotate at different speeds relative to the ring gear (one faster, one slower) by, say, 2 full turns each (4 full turns relative to each other), resulting in the left wheel mak ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bavaria
Bavaria ( ; ), officially the Free State of Bavaria (german: Freistaat Bayern, link=no ), is a state in the south-east of Germany. With an area of , Bavaria is the largest German state by land area, comprising roughly a fifth of the total land area of Germany. With over 13 million inhabitants, it is second in population only to North Rhine-Westphalia, but due to its large size its population density is below the German average. Bavaria's main cities are Munich (its capital and largest city and also the third largest city in Germany), Nuremberg, and Augsburg. The history of Bavaria includes its earliest settlement by Iron Age Celtic tribes, followed by the conquests of the Roman Empire in the 1st century BC, when the territory was incorporated into the provinces of Raetia and Noricum. It became the Duchy of Bavaria (a stem duchy) in the 6th century AD following the collapse of the Western Roman Empire. It was later incorporated into the Holy Roman Empire, became an ind ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jacob Hochbrucker
Jacob Hochbrucker (also spelled ''Jakob Hochprugger''; 1673 – 28 May 1763) was an eighteenth-century harp maker and musician credited with the invention of the single-action pedal harp popularized in Europe between 1729 and 1750 by his descendants, and particularly by the Dauphine, Marie Antoinette, who performed on it after her arrival in Paris in 1770. Life and work Hochbrucker was probably born in Mindelheim. From 1699 he lived and worked in Donauwörth, where he also built lutes and violas. Around 1720 Hochbrucker invented the pedal mechanism to play the harp, adding to the instrument five (later increased to seven) pedals and connecting them to the hooks for the C, D, F, G, and B strings, thus allowing the player to alter the strings sound of a semitone and greatly extend the range of the instrument for the extraction of sounds. This ingenious chromatic system later became the subject matter of studies and extended considerations. In the second half of the 18th century, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pedal Harp
The pedal harp (also known as the concert harp) is a large and technologically modern harp, designed primarily for use in art music. It may be played solo, as part of a chamber ensemble, or in an orchestra. It typically has 47 strings with seven strings per octave, giving a range of six and a half octaves. In this type of harp the pedals alter the pitch of the strings, so that the pedal harp can easily play works written in any key. This is particularly important in the harmonically complex music of the Romantic period and later 20th-century classical music. Parts Body and strings A pedal harp typically stands about high, is deep, and wide at the bass end of the soundboard. It weighs about . The body of the harp consists of a straight upright pillar, sometimes adorned with a crown at the top; a soundboard, which in most harps is pear-shaped with additional width at the bottom, although some older instruments have soundboards that are straight-sided but widening toward t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Velocity
Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity is a fundamental concept in kinematics, the branch of classical mechanics that describes the motion of bodies. Velocity is a physical vector quantity; both magnitude and direction are needed to define it. The scalar absolute value (magnitude) of velocity is called , being a coherent derived unit whose quantity is measured in the SI (metric system) as metres per second (m/s or m⋅s−1). For example, "5 metres per second" is a scalar, whereas "5 metres per second east" is a vector. If there is a change in speed, direction or both, then the object is said to be undergoing an ''acceleration''. Constant velocity vs acceleration To have a ''constant velocity'', an object must have a constant speed in a constant direction. Constant direction cons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Channel Islands
The Channel Islands ( nrf, Îles d'la Manche; french: îles Anglo-Normandes or ''îles de la Manche'') are an archipelago in the English Channel, off the French coast of Normandy. They include two Crown Dependencies: the Bailiwick of Jersey, which is the largest of the islands; and the Bailiwick of Guernsey, consisting of Guernsey, Alderney, Sark, Herm and some smaller islands. They are considered the remnants of the Duchy of Normandy and, although they are not part of the United Kingdom, the UK is responsible for the defence and international relations of the islands. The Crown dependencies are not members of the Commonwealth of Nations, nor have they ever been in the European Union. They have a total population of about , and the bailiwicks' capitals, Saint Helier and Saint Peter Port, have populations of 33,500 and 18,207, respectively. "Channel Islands" is a geographical term, not a political unit. The two bailiwicks have been administered separately since the late ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chronograph
A chronograph is a specific type of watch that is used as a stopwatch combined with a display watch. A basic chronograph has an independent sweep second hand and a minute sub-dial; it can be started, stopped, and returned to zero by successive pressure on the stem. More complex chronographs use additional Complication (horology), complications and can have multiple sub-dials to measure seconds, minutes, hours and even fractions of a second. In addition, many modern chronographs use moveable bezels as Tachymeter (watch), tachymeters for rapid calculations of speed or distance. Louis Moinet invented the chronograph in 1816 for use in tracking astronomical objects. Chronographs were also used heavily in artillery fire in the mid to late 1800s. More modern uses of chronographs involve aircraft piloting, auto racing, Underwater diving, diving and submarine maneuvering. Since the 1980s, the term ''chronograph'' has also been applied to all Watch#Digital, digital watches that incorpor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gold
Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile metal in a pure form. Chemically, gold is a transition metal and a group 11 element. It is one of the least reactive chemical elements and is solid under standard conditions. Gold often occurs in free elemental ( native state), as nuggets or grains, in rocks, veins, and alluvial deposits. It occurs in a solid solution series with the native element silver (as electrum), naturally alloyed with other metals like copper and palladium, and mineral inclusions such as within pyrite. Less commonly, it occurs in minerals as gold compounds, often with tellurium (gold tellurides). Gold is resistant to most acids, though it does dissolve in aqua regia (a mixture of nitric acid and hydrochloric acid), forming a soluble tetrachloroaurate anion. Gold is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carat (purity)
The fineness of a precious metal object (coin, bar, jewelry, etc.) represents the weight of ''fine metal'' therein, in proportion to the total weight which includes alloying base metals and any impurities. Alloy metals are added to increase hardness and durability of coins and jewelry, alter colors, decrease the cost per weight, or avoid the cost of high-purity refinement. For example, copper is added to the precious metal silver to make a more durable alloy for use in coins, housewares and jewelry. Coin silver, which was used for making silver coins in the past, contains 90% silver and 10% copper, by mass. Sterling silver contains 92.5% silver and 7.5% of other metals, usually copper, by mass. Various ways of expressing fineness have been used and two remain in common use: ''millesimal fineness'' expressed in units of parts per 1,000 and '' karats'' or ''carats'' used only for gold. Karats measure the parts per 24, so that 18 karat = = 75% and 24 karat gold is considered 100% g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zinc
Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic table. In some respects, zinc is chemically similar to magnesium: both elements exhibit only one normal oxidation state (+2), and the Zn2+ and Mg2+ ions are of similar size.The elements are from different metal groups. See periodic table. Zinc is the 24th most abundant element in Earth's crust and has five stable isotopes. The most common zinc ore is sphalerite (zinc blende), a zinc sulfide mineral. The largest workable lodes are in Australia, Asia, and the United States. Zinc is refined by froth flotation of the ore, roasting, and final extraction using electricity ( electrowinning). Zinc is an essential trace element for humans, animals, plants and for microorganisms and is necessary for prenatal and postnatal development. It ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.svg "Click for more on -> Bavaria")
.jpg "Click for more on -> Chronograph")
