1.
Water clock (Indianapolis)
–
The Water Clock, also known as The Giant Water Clock, is in the permanent collection of The Childrens Museum of Indianapolis located in Indianapolis, Indiana, United States. The modern water clock is located in the Sunburst Atrium of The Childrens Museum and it was created by French scientist and artist Bernard Gitton in 1988, the same year that the museum acquired it. The 26. 5-foot artistic timepiece is the largest water clock in North America, the water clock, created by French chemist and artist Bernard Gitton, is approximately 30 feet tall and made of more than 40 pieces of glass and 100 pieces of metal. The lights on the clock are bright green and the water is dyed blue, the clock is made of glass, steel, and 70 US gallons of a solution of deionized water, methyl alcohol, and coloring dye. It was assembled in France to ensure that it worked, then dissassembled and shipped to Indianapolis and it was assembled again in the Childrens Museum over two weeks time. Functionally, a Gitton water clock consists of four subsystems, An oscillator, a divider, a minute counter. Water from a pump in the basement, just below the clock, is pumped through a running up the middle of the clock into a reservoir at the top. The water then drips down onto a scoop at the top which is connected to the green, the pendulum causes the scoop to dump the water into a series of siphons. The siphons fill and empty into the minutes globes, a Siphon is a tube in an inverted U shape which causes the solution to flow up, without pumps, powered by the fall of the liquid as it flows down the tube under the pull of gravity. One minute globe represents two minutes, when all thirty-minute globes are full, they empty and an additional hour globe fills. Twice a day, at one oclock, all of the globes and minute discs are full. Moving water makes a siphon -\ You will not see it pull \ Til it reaches to the minutes sphere \ And makes the water flow, at every single hour \ When the minutes side is full \ The minutes matching U-tube burps, \ Another siphon pulls. The water clock has two pumps in the basement – one that keeps the working, and a backup in case the first fails. The 70 US gallons of fluid in the clock is not pure water and it is composed of deionized water, coloring, and methyl alcohol. The color of the water can be changed by stopping the clock, draining the water, the creator of this Water Clock is Bernard Gitton who completed the clock in 1988 and brought it piece by piece to the museum to be assembled. Bernard Gitton is a French physical chemist and artist who combines those two by creating water clocks, water calculators, fountains, and other items of art and science, since 1979. Bernard began making items of artistic science at the age of 43, hornsby Water Clock The Childrens Museum of Indianapolis website This Weeks Wow, Episode 11, The Water Clock
Water clock (Indianapolis)
–
The Water Clock inside
The Children's Museum of Indianapolis
2.
Greek language
–
Greek is an independent branch of the Indo-European family of languages, native to Greece and other parts of the Eastern Mediterranean. It has the longest documented history of any living language, spanning 34 centuries of written records and its writing system has been the Greek alphabet for the major part of its history, other systems, such as Linear B and the Cypriot syllabary, were used previously. The alphabet arose from the Phoenician script and was in turn the basis of the Latin, Cyrillic, Armenian, Coptic, Gothic and many other writing systems. Together with the Latin texts and traditions of the Roman world, during antiquity, Greek was a widely spoken lingua franca in the Mediterranean world and many places beyond. It would eventually become the official parlance of the Byzantine Empire, the language is spoken by at least 13.2 million people today in Greece, Cyprus, Italy, Albania, Turkey, and the Greek diaspora. Greek roots are used to coin new words for other languages, Greek. Greek has been spoken in the Balkan peninsula since around the 3rd millennium BC, the earliest written evidence is a Linear B clay tablet found in Messenia that dates to between 1450 and 1350 BC, making Greek the worlds oldest recorded living language. Among the Indo-European languages, its date of earliest written attestation is matched only by the now extinct Anatolian languages, the Greek language is conventionally divided into the following periods, Proto-Greek, the unrecorded but assumed last ancestor of all known varieties of Greek. The unity of Proto-Greek would have ended as Hellenic migrants entered the Greek peninsula sometime in the Neolithic era or the Bronze Age, Mycenaean Greek, the language of the Mycenaean civilisation. It is recorded in the Linear B script on tablets dating from the 15th century BC onwards, Ancient Greek, in its various dialects, the language of the Archaic and Classical periods of the ancient Greek civilisation. It was widely known throughout the Roman Empire, after the Roman conquest of Greece, an unofficial bilingualism of Greek and Latin was established in the city of Rome and Koine Greek became a first or second language in the Roman Empire. The origin of Christianity can also be traced through Koine Greek, Medieval Greek, also known as Byzantine Greek, the continuation of Koine Greek in Byzantine Greece, up to the demise of the Byzantine Empire in the 15th century. Much of the written Greek that was used as the language of the Byzantine Empire was an eclectic middle-ground variety based on the tradition of written Koine. Modern Greek, Stemming from Medieval Greek, Modern Greek usages can be traced in the Byzantine period and it is the language used by the modern Greeks, and, apart from Standard Modern Greek, there are several dialects of it. In the modern era, the Greek language entered a state of diglossia, the historical unity and continuing identity between the various stages of the Greek language is often emphasised. Greek speakers today still tend to regard literary works of ancient Greek as part of their own rather than a foreign language and it is also often stated that the historical changes have been relatively slight compared with some other languages. According to one estimation, Homeric Greek is probably closer to demotic than 12-century Middle English is to modern spoken English, Greek is spoken by about 13 million people, mainly in Greece, Albania and Cyprus, but also worldwide by the large Greek diaspora. Greek is the language of Greece, where it is spoken by almost the entire population
Greek language
–
Idealized portrayal of
Homer
Greek language
–
regions where Greek is the official language
Greek language
–
Greek language road sign, A27 Motorway, Greece
3.
Timepiece
–
A clock is an instrument to measure, keep, and indicate time. The word clock is derived from the Celtic words clagan and clocca meaning bell, a silent instrument missing such a striking mechanism has traditionally been known as a timepiece. In general usage today a clock refers to any device for measuring and displaying the time, Watches and other timepieces that can be carried on ones person are often distinguished from clocks. The clock is one of the oldest human inventions, meeting the need to measure intervals of time shorter than the natural units, the day, the lunar month. Devices operating on several physical processes have been used over the millennia, a sundial shows the time by displaying the position of a shadow on a flat surface. There is a range of duration timers, an example being the hourglass. Water clocks, along with the sundials, are possibly the oldest time-measuring instruments, spring-driven clocks appeared during the 15th century. During the 15th and 16th centuries, clockmaking flourished, the next development in accuracy occurred after 1656 with the invention of the pendulum clock. A major stimulus to improving the accuracy and reliability of clocks was the importance of precise time-keeping for navigation, the electric clock was patented in 1840. The development of electronics in the 20th century led to clocks with no clockwork parts at all, the timekeeping element in every modern clock is a harmonic oscillator, a physical object that vibrates or oscillates at a particular frequency. This object can be a pendulum, a fork, a quartz crystal. Analog clocks usually indicate time using angles, Digital clocks display a numeric representation of time. Two numeric display formats are used on digital clocks, 24-hour notation. Most digital clocks use electronic mechanisms and LCD, LED, or VFD displays, for convenience, distance, telephony or blindness, auditory clocks present the time as sounds. There are also clocks for the blind that have displays that can be read by using the sense of touch, some of these are similar to normal analog displays, but are constructed so the hands can be felt without damaging them. The evolution of the technology of clocks continues today, the study of timekeeping is known as horology. The apparent position of the Sun in the sky moves over the course of a day, shadows cast by stationary objects move correspondingly, so their positions can be used to indicate the time of day. A sundial shows the time by displaying the position of a shadow on a flat surface, sundials can be horizontal, vertical, or in other orientations
Timepiece
–
The
Swiss railway clock.
Timepiece
–
The
Shepherd gate clock at the
Royal Observatory, Greenwich.
Timepiece
–
Simple horizontal sundial.
Timepiece
–
The flow of
sand in an
hourglass can be used to keep track of elapsed time.
4.
Babylon
–
Babylon was a major city of ancient Mesopotamia in the fertile plain between the Tigris and Euphrates rivers. The city was built upon the Euphrates and divided in parts along its left and right banks. Babylon was originally a small Semitic Akkadian city dating from the period of the Akkadian Empire c.2300 BC, the town attained independence as part of a small city-state with the rise of the First Amorite Babylonian Dynasty in 1894 BC. Babylon grew and South Mesopotamia came to be known as Babylonia, the empire quickly dissolved after Hammurabis death and Babylon spent long periods under Assyrian, Kassite and Elamite domination. After being destroyed and then rebuilt by the Assyrians, Babylon became the capital of the Neo-Babylonian Empire from 609 to 539 BC, the Hanging Gardens of Babylon was one of the Seven Wonders of the Ancient World. After the fall of the Neo-Babylonian Empire, the city came under the rule of the Achaemenid, Seleucid, Parthian, Roman, and Sassanid empires. It has been estimated that Babylon was the largest city in the world from c.1770 to 1670 BC and it was perhaps the first city to reach a population above 200,000. Estimates for the extent of its area range from 890 to 900 hectares. The remains of the city are in present-day Hillah, Babil Governorate, Iraq, about 85 kilometres south of Baghdad, comprising a large tell of broken mud-brick buildings, the English Babylon comes from Greek Babylṓn, a transliteration of the Akkadian Babili. The Babylonian name in the early 2nd millennium BC had been Babilli or Babilla, by the 1st millennium BC, it had changed to Babili under the influence of the folk etymology which traced it to bāb-ili. The Gate of God or Gate of El being from the Aramaic Hebrew Bab for Gate and El for God and this being similar to the Hebrew word for confusion Balal. In the Bible, the name appears as Babel, interpreted in the Hebrew Scriptures Book of Genesis to mean confusion, the modern English verb, to babble, or to speak meaningless words, is popularly thought to derive from this name, but there is no direct connection. The remains of the city are in present-day Hillah, Babil Governorate, Iraq, about 85 kilometers south of Baghdad, comprising a large tell of broken mud-brick buildings and debris. The site at Babylon consists of a number of mounds covering an area of about 2 by 1 kilometer, oriented north to south, along the Euphrates to the west. Originally, the river roughly bisected the city, but the course of the river has since shifted so that most of the remains of the western part of the city are now inundated. Some portions of the city wall to the west of the river also remain, remains of the city include, Kasr—also called Palace or Castle, it is the location of the Neo-Babylonian ziggurat Etemenanki and lies in the center of the site. Amran Ibn Ali—the highest of the mounds at 25 meters, to the south and it is the site of Esagila, a temple of Marduk which also contained shrines to Ea and Nabu. Homera—a reddish colored mound on the west side, most of the Hellenistic remains are here
Babylon
–
A partial view of the ruins of Babylon from
Saddam Hussein 's Summer Palace
Babylon
–
Plan of Ruins of Babylon, 1905
Babylon
–
Babylon in 1932
Babylon
–
The
Queen of the Night relief. The figure could be an aspect of the goddess
Ishtar, Babylonian goddess of sex and love.
5.
Egypt
–
Egypt, officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia by a land bridge formed by the Sinai Peninsula. Egypt is a Mediterranean country bordered by the Gaza Strip and Israel to the northeast, the Gulf of Aqaba to the east, the Red Sea to the east and south, Sudan to the south, and Libya to the west. Across the Gulf of Aqaba lies Jordan, and across from the Sinai Peninsula lies Saudi Arabia, although Jordan and it is the worlds only contiguous Afrasian nation. Egypt has among the longest histories of any country, emerging as one of the worlds first nation states in the tenth millennium BC. Considered a cradle of civilisation, Ancient Egypt experienced some of the earliest developments of writing, agriculture, urbanisation, organised religion and central government. One of the earliest centres of Christianity, Egypt was Islamised in the century and remains a predominantly Muslim country. With over 92 million inhabitants, Egypt is the most populous country in North Africa and the Arab world, the third-most populous in Africa, and the fifteenth-most populous in the world. The great majority of its people live near the banks of the Nile River, an area of about 40,000 square kilometres, the large regions of the Sahara desert, which constitute most of Egypts territory, are sparsely inhabited. About half of Egypts residents live in areas, with most spread across the densely populated centres of greater Cairo, Alexandria. Modern Egypt is considered to be a regional and middle power, with significant cultural, political, and military influence in North Africa, the Middle East and the Muslim world. Egypts economy is one of the largest and most diversified in the Middle East, Egypt is a member of the United Nations, Non-Aligned Movement, Arab League, African Union, and Organisation of Islamic Cooperation. Miṣr is the Classical Quranic Arabic and modern name of Egypt. The name is of Semitic origin, directly cognate with other Semitic words for Egypt such as the Hebrew מִצְרַיִם, the oldest attestation of this name for Egypt is the Akkadian
Egypt
–
The
Giza Necropolis is the oldest of the
ancient Wonders and the only one still in existence.
Egypt
–
Flag
Egypt
–
The Greek Ptolemaic queen
Cleopatra VII and her son by Julius Caesar,
Caesarion at the
Temple of Dendera.
Egypt
–
The 1803
Cedid Atlas, showing
Ottoman Egypt.
6.
India
–
India, officially the Republic of India, is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and it is bounded by the Indian Ocean on the south, the Arabian Sea on the southwest, and the Bay of Bengal on the southeast. It shares land borders with Pakistan to the west, China, Nepal, and Bhutan to the northeast, in the Indian Ocean, India is in the vicinity of Sri Lanka and the Maldives. Indias Andaman and Nicobar Islands share a border with Thailand. The Indian subcontinent was home to the urban Indus Valley Civilisation of the 3rd millennium BCE, in the following millennium, the oldest scriptures associated with Hinduism began to be composed. Social stratification, based on caste, emerged in the first millennium BCE, early political consolidations took place under the Maurya and Gupta empires, the later peninsular Middle Kingdoms influenced cultures as far as southeast Asia. In the medieval era, Judaism, Zoroastrianism, Christianity, and Islam arrived, much of the north fell to the Delhi sultanate, the south was united under the Vijayanagara Empire. The economy expanded in the 17th century in the Mughal empire, in the mid-18th century, the subcontinent came under British East India Company rule, and in the mid-19th under British crown rule. A nationalist movement emerged in the late 19th century, which later, under Mahatma Gandhi, was noted for nonviolent resistance, in 2015, the Indian economy was the worlds seventh largest by nominal GDP and third largest by purchasing power parity. Following market-based economic reforms in 1991, India became one of the major economies and is considered a newly industrialised country. However, it continues to face the challenges of poverty, corruption, malnutrition, a nuclear weapons state and regional power, it has the third largest standing army in the world and ranks sixth in military expenditure among nations. India is a constitutional republic governed under a parliamentary system. It is a pluralistic, multilingual and multi-ethnic society and is home to a diversity of wildlife in a variety of protected habitats. The name India is derived from Indus, which originates from the Old Persian word Hindu, the latter term stems from the Sanskrit word Sindhu, which was the historical local appellation for the Indus River. The ancient Greeks referred to the Indians as Indoi, which translates as The people of the Indus, the geographical term Bharat, which is recognised by the Constitution of India as an official name for the country, is used by many Indian languages in its variations. Scholars believe it to be named after the Vedic tribe of Bharatas in the second millennium B. C. E and it is also traditionally associated with the rule of the legendary emperor Bharata. Gaṇarājya is the Sanskrit/Hindi term for republic dating back to the ancient times, hindustan is a Persian name for India dating back to the 3rd century B. C. E. It was introduced into India by the Mughals and widely used since then and its meaning varied, referring to a region that encompassed northern India and Pakistan or India in its entirety
India
–
Flag
India
–
The granite
tower of
Brihadeeswarar Temple in
Thanjavur was completed in 1010 CE by
Raja Raja Chola I.
India
–
Writing the will and testament of the Mughal king court in Persian, 1590–1595
7.
China
–
China, officially the Peoples Republic of China, is a unitary sovereign state in East Asia and the worlds most populous country, with a population of over 1.381 billion. The state is governed by the Communist Party of China and its capital is Beijing, the countrys major urban areas include Shanghai, Guangzhou, Beijing, Chongqing, Shenzhen, Tianjin and Hong Kong. China is a power and a major regional power within Asia. Chinas landscape is vast and diverse, ranging from forest steppes, the Himalaya, Karakoram, Pamir and Tian Shan mountain ranges separate China from much of South and Central Asia. The Yangtze and Yellow Rivers, the third and sixth longest in the world, respectively, Chinas coastline along the Pacific Ocean is 14,500 kilometers long and is bounded by the Bohai, Yellow, East China and South China seas. China emerged as one of the worlds earliest civilizations in the basin of the Yellow River in the North China Plain. For millennia, Chinas political system was based on hereditary monarchies known as dynasties, in 1912, the Republic of China replaced the last dynasty and ruled the Chinese mainland until 1949, when it was defeated by the communist Peoples Liberation Army in the Chinese Civil War. The Communist Party established the Peoples Republic of China in Beijing on 1 October 1949, both the ROC and PRC continue to claim to be the legitimate government of all China, though the latter has more recognition in the world and controls more territory. China had the largest economy in the world for much of the last two years, during which it has seen cycles of prosperity and decline. Since the introduction of reforms in 1978, China has become one of the worlds fastest-growing major economies. As of 2016, it is the worlds second-largest economy by nominal GDP, China is also the worlds largest exporter and second-largest importer of goods. China is a nuclear weapons state and has the worlds largest standing army. The PRC is a member of the United Nations, as it replaced the ROC as a permanent member of the U. N. Security Council in 1971. China is also a member of numerous formal and informal multilateral organizations, including the WTO, APEC, BRICS, the Shanghai Cooperation Organization, the BCIM, the English name China is first attested in Richard Edens 1555 translation of the 1516 journal of the Portuguese explorer Duarte Barbosa. The demonym, that is, the name for the people, Portuguese China is thought to derive from Persian Chīn, and perhaps ultimately from Sanskrit Cīna. Cīna was first used in early Hindu scripture, including the Mahābhārata, there are, however, other suggestions for the derivation of China. The official name of the state is the Peoples Republic of China. The shorter form is China Zhōngguó, from zhōng and guó and it was then applied to the area around Luoyi during the Eastern Zhou and then to Chinas Central Plain before being used as an occasional synonym for the state under the Qing
China
–
Yinxu, ruins of an ancient
palace dating from the
Shang Dynasty (14th century BCE)
China
–
Flag
China
–
Some of the thousands of life-size
Terracotta Warriors of the
Qin Dynasty, c. 210 BCE
China
–
The
Great Wall of China was built by several dynasties over two thousand years to protect the sedentary agricultural regions of the
Chinese interior from incursions by
nomadic pastoralists of the northern
steppes.
8.
Pendulum
–
A pendulum is a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced sideways from its resting, equilibrium position, when released, the restoring force combined with the pendulums mass causes it to oscillate about the equilibrium position, swinging back and forth. The time for one cycle, a left swing and a right swing, is called the period. The period depends on the length of the pendulum and also to a degree on the amplitude. Pendulums are also used in instruments such as accelerometers and seismometers. Historically they were used as gravimeters to measure the acceleration of gravity in geophysical surveys, the word pendulum is new Latin, from the Latin pendulus, meaning hanging. The simple gravity pendulum is a mathematical model of a pendulum. This is a weight on the end of a massless cord suspended from a pivot, when given an initial push, it will swing back and forth at a constant amplitude. Real pendulums are subject to friction and air drag, so the amplitude of their swings declines and it is independent of the mass of the bob. For small swings the period of swing is approximately the same for different size swings, that is and this property, called isochronism, is the reason pendulums are so useful for timekeeping. Successive swings of the pendulum, even if changing in amplitude, for larger amplitudes, the period increases gradually with amplitude so it is longer than given by equation. For example, at an amplitude of θ0 = 23° it is 1% larger than given by, the period increases asymptotically as θ0 approaches 180°, because the value θ0 = 180° is an unstable equilibrium point for the pendulum. The length L used to calculate the period of the simple pendulum in eq. above is the distance from the pivot point to the center of mass of the bob. Any swinging rigid body free to rotate about a horizontal axis is called a compound pendulum or physical pendulum. The appropriate equivalent length L for calculating the period of any such pendulum is the distance from the pivot to the center of oscillation. This point is located under the center of mass at a distance from the pivot traditionally called the radius of oscillation, if most of the mass is concentrated in a relatively small bob compared to the pendulum length, the center of oscillation is close to the center of mass. Substituting this expression in above, the period T of a pendulum is given by T =2 π I m g R for sufficiently small oscillations. For example, a rigid rod of length L pivoted about one end has moment of inertia I = m L2 /3
Pendulum
–
Replica of Zhang Heng's seismometer. The pendulum is contained inside.
Pendulum
–
"Simple gravity pendulum" model assumes no friction or air resistance.
Pendulum
–
Ornamented pendulum in a French Comtoise clock
Pendulum
–
Invar pendulum in low pressure tank in
Riefler regulator clock, used as the US time standard from 1909 to 1929
9.
Water wheel
–
A water wheel is a machine for converting the energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a wheel, with a number of blades or buckets arranged on the outside rim forming the driving surface. Most commonly, the wheel is mounted vertically on a horizontal axle, vertical wheels can transmit power either through the axle or via a ring gear and typically drive belts or gears, horizontal wheels usually directly drive their load. Water wheels were still in use well into the 20th century. Uses included milling flour in gristmills, grinding wood into pulp for papermaking, hammering wrought iron, machining, some water wheels are fed by water from a mill pond, which is formed when a flowing stream is dammed. A channel for the water flowing to or from a wheel is called a mill race. The race bringing water from the pond to the water wheel is a headrace. In the mid to late 18th century John Smeatons scientific investigation of the water led to significant increases in efficiency supplying much needed power for the Industrial Revolution. Water wheels began being displaced by the smaller, less expensive and more efficient turbine, developed by Benoît Fourneyron, turbines are capable of handling high heads, or elevations, that exceed the capability of practical-sized waterwheels. The main difficulty of water wheels is their dependence on flowing water, modern hydroelectric dams can be viewed as the descendants of the water wheel, as they too take advantage of the movement of water downhill. The two main functions of water wheels were historically water-lifting for irrigation purposes and as a power source, when used for water-lifting power can be supplied by either human or animal force or by the water current itself. Water wheels come in two designs, either a vertical or a horizontal axle. The latter type can be subdivided, depending on where the hits the wheel. Engineers of the Hellenistic era Mediterranean region are credited with the development of the water wheel, Mediterranean engineers of the Hellenistic and Roman periods were also the first to use it for both irrigation and as a power source. The technological breakthrough occurred in the advanced and scientifically minded Hellenistic period between the 3rd and 1st centuries BCE. This is seen as an evolution of the paddle-driven water-lifting wheels that had appeared in ancient Egypt by the 4th century BCE. According to John Peter Oleson, both the wheel and the hydraulic Noria appeared in Egypt by the 4th century BCE. This is supported by finds at Faiyum, where the oldest archeological evidence of a water-wheel has been found
Water wheel
–
An overshot waterwheel standing 42 ft (13 m) high powers the Old Mill at
Berry College in
Rome, Georgia, USA
Water wheel
–
Water wheel powering a
mine hoist in
De re metallica (1566)
Water wheel
–
Sequence of wheels found in
Rio Tinto mines, southwestern Spain
Water wheel
–
Reconstruction of
Vitruvius ' undershot-wheeled watermill
10.
Escapement
–
An escapement is a device in mechanical watches and clocks that transfers energy to the timekeeping element and allows the number of its oscillations to be counted. The impulse action transfers energy to the timekeeping element to replace the energy lost to friction during its cycle. The escapement is driven by force from a spring or a suspended weight. Each swing of the pendulum or balance wheel releases a tooth of the escape wheel gear. This regular periodic advancement moves the hands forward at a steady rate. At the same time the tooth gives the timekeeping element a push, before another tooth catches on the escapements pallet, the sudden stopping of the escapements tooth is what generates the characteristic ticking sound heard in operating mechanical clocks and watches. Escapements are used elsewhere as well, manual typewriters used escapements to step the carriage as each letter was typed. The importance of the escapement in the history of technology is that it was the key invention that made the all-mechanical clock possible, oscillating timekeepers are used in every modern clock. The earliest liquid-driven escapement was described by the Greek engineer Philo of Byzantium in his technical treatise Pneumatics as part of a washstand, a counterweighted spoon, supplied by a water tank, tips over in a basin when full, releasing a spherical piece of pumice in the process. Once the spoon has emptied, it is pulled up again by the counterweight, remarkably, Philos comment that its construction is similar to that of clocks indicates that such escapement mechanisms were already integrated in ancient water clocks. In China, the Tang dynasty Buddhist monk Yi Xing along with government official Liang Lingzan made the escapement in 723 to the workings of an armillary sphere. Song dynasty horologists Zhang Sixun and Su Song duly applied escapement devices for their astronomical clock towers, according to historian Derek J. de Solla Price, the medieval Chinese escapement spread west and was the source for Western escapement technology. Hassan, a mercury escapement in a Spanish work for Alfonso X in 1277 can be traced back to earlier Arabic sources, knowledge of these mercury escapements may have spread through Europe with translations of Arabic and Spanish texts. However, none of these were true mechanical escapements, since they depended on the flow of liquid through an orifice to measure time. For example, in Su Songs clock, water flowed into a container on a pivot, the escapements role was to tip the container over each time it filled up, thus advancing the clocks wheels each time an equal quantity of water was measured out. The time between releases depended on the rate of flow, which decreased with water pressure as the level of water in the source container dropped. The development of mechanical clocks depended on the invention of an escapement which would allow a movement to be controlled by an oscillating weight. The Chinese one worked intermittently, the European, in discrete, both systems used gravity as the prime mover, but the action was very different
Escapement
–
Pin wheel escapement of
South Mymms tower clock
Escapement
–
Greek washstand
automaton of the 3rd century BC working by the earliest known instance of an escapement mechanism
Escapement
–
First detent escapement by
Pierre Le Roy 1748.
Escapement
–
Earnshaw's detent escapement, used widely in chronometers.
11.
Automaton
–
An automaton is a self-operating machine, or a machine or control mechanism designed to automatically follow a predetermined sequence of operations, or respond to predetermined instructions. Some automata, such as bellstrikers in mechanical clocks, are designed to give the illusion to the observer that they are operating under their own power. The word automaton is the latinization of the Greek αὐτόματον, automaton and this word was first used by Homer to describe automatic door opening, or automatic movement of wheeled tripods. The automata in the Hellenistic world were intended as tools, toys, religious idols and he had invented the worlds first cuckoo clock. Complex mechanical devices are known to have existed in Hellenistic Greece, though the surviving example is the Antikythera mechanism. However, the information gleaned from recent scans of the fragments indicate that it may have come from the colonies of Corinth in Sicily and its also said that when King Solomon stepped upon the throne, a mechanism was set in motion. As soon as he stepped upon the first step, a golden ox, on each side, the animals helped the King up until he was comfortably seated upon the throne. In ancient China, an account of automata is found in the Lie Zi text. Within it there is a description of an earlier encounter between King Mu of Zhou and a mechanical engineer known as Yan Shi, an artificer. The latter proudly presented the king with a life-size, human-shaped figure of his mechanical handiwork and it walked with rapid strides, moving its head up and down, so that anyone would have taken it for a live human being. The artificer touched its chin, and it began singing, perfectly in tune and he touched its hand, and it began posturing, keeping perfect time. And, indeed, it turned out to be only a construction of leather, wood, glue and lacquer, variously coloured white, black, red, other notable examples of automata include Archytass dove, mentioned by Aulus Gellius. The manufacturing tradition of automata continued in the Greek world well into the Middle Ages, similar automata in the throne room were described by Luitprands contemporary Constantine Porphyrogenitus, who later became emperor, in his book Περὶ τῆς Βασιλείου Τάξεως. In the mid-8th century, the first wind powered automata were built, statues that turned with the wind over the domes of the four gates, the public spectacle of wind-powered statues had its private counterpart in the Abbasid palaces where automata of various types were predominantly displayed. In 827, Caliph Al-Mamun had a silver and golden tree in his palace in Baghdad, there were metal birds that sang automatically on the swinging branches of this tree built by Muslim inventors and engineers. The Abbasid Caliph Al-Muqtadir also had a tree in his palace in Baghdad in 915, with birds on it flapping their wings. In the 9th century, the Banū Mūsā brothers invented an automatic flute player. Al-Jazari described complex programmable humanoid automata amongst other machines he designed and constructed in the Book of Knowledge of Ingenious Mechanical Devices in 1206 and his automaton was a boat with four automatic musicians that floated on a lake to entertain guests at royal drinking parties
Automaton
–
The
Digesting Duck by
Jacques de Vaucanson, hailed in 1739 as the first automaton capable of
digestion.
Automaton
–
The
Antikythera mechanism from 150–100 BC was designed to calculate the positions of astronomical objects.
Automaton
–
Automaton in the
Swiss Museum CIMA.
Automaton
–
Tea-serving Japanese automaton, "
karakuri ningyō ", with mechanism (right), 19th century.
12.
Byzantium
–
Byzantium was an ancient Greek colony that later became Constantinople, and later still Istanbul. Byzantium was colonised by the Greeks from Megara in c. 657 BC, the etymology of Byzantion is unknown. It has been suggested that the name is of Thraco-Illyrian origin and it may be derived from a Thracian or Illyrian personal name, Byzas. Ancient Greek legend refers to a king Byzas, the leader of the Megarian colonists, the form Byzantium is a Latinisation of the original name. Much later, the name Byzantium became common in the West to refer to the Eastern Roman Empire and this usage was introduced only in 1555 by the historian Hieronymus Wolf, a century after the empire had ceased to exist. During the time of the empire, the term Byzantium was restricted to just the city, the European side featured only two fishing settlements, Lygos and Semistra. The origins of Byzantium are shrouded in legend, the traditional legend has it that Byzas from Megara founded Byzantium in 667 BC when he sailed northeast across the Aegean Sea. The tradition tells that Byzas, son of King Nisos, planned to found a colony of the Dorian Greek city of Megara, Byzas consulted the oracle of Apollo at Delphi, which instructed Byzas to settle opposite the Land of the Blind. Leading a group of Megarian colonists, Byzas found a location where the Golden Horn and he adjudged the Chalcedonians blind not to have recognized the advantages the land on the European side of the Bosphorus had over the Asiatic side. In 667 BC he founded Byzantium at their location, thus fulfilling the oracles requirement and it was mainly a trading city due to its location at the Black Seas only entrance. Byzantium later conquered Chalcedon, across the Bosporus on the Asiatic side, Byzantium was besieged by Greek forces during the Peloponnesian War. As part of Spartas strategy for cutting off supplies to Athens. The Athenian military later took the city in 408 BC, after siding with Pescennius Niger against the victorious Septimius Severus, the city was besieged by Roman forces and suffered extensive damage in 196 AD. Byzantium was rebuilt by Septimius Severus, now emperor, and quickly regained its previous prosperity and it was bound to Perinthos during the period of Septimius Severus. The location of Byzantium attracted Roman Emperor Constantine I who, in 330 AD, after his death the city was called Constantinople. This combination of imperialism and location would affect Constantinoples role as the nexus between the continents of Europe and Asia and it was a commercial, cultural, and diplomatic centre. With its strategic position, Constantinople controlled the trade routes between Asia and Europe, as well as the passage from the Mediterranean Sea to the Black Sea. On May 29,1453, the city fell to the Ottoman Turks, and again became the capital of a powerful state, the Turks called the city Istanbul, the name derives from eis-tin-polin
Byzantium
–
O: Head of
Alexander the Great with
Amun's horns.
Byzantium
–
Location of Byzantium
Byzantium
–
Byzantine lamellar klivanium (Κλιβάνιον) - a predecessor of ottoman krug
mirror armour
13.
Epicyclic gearing
–
An epicyclic gear train consists of two gears mounted so that the center of one gear revolves around the center of the other. A carrier connects the centers of the two gears and rotates to carry one gear, called the planet gear, around the other, the planet and sun gears mesh so that their pitch circles roll without slip. A point on the circle of the planet gear traces an epicycloid curve. In this simplified case, the sun gear is fixed and the planetary gear roll around the sun gear. An epicyclic gear train can be assembled so the planet gear rolls on the inside of the circle of a fixed, outer gear ring, or ring gear. In this case, the curve traced by a point on the circle of the planet is a hypocycloid. The combination of gear trains with a planet engaging both a sun gear and a ring gear is called a planetary gear train. In this case, the gear is usually fixed and the sun gear is driven. Epicyclic gears get their name from their earliest application, which was the modeling of the movements of the planets in the heavens. Believing the planets, as everything in the heavens, to be perfect, they could travel in perfect circles. At around 500 BC, the Greeks invented the idea of epicycles, with this theory Claudius Ptolemy in the Almagest in 148 AD was able to predict planetary orbital paths. The Antikythera Mechanism, circa 80 BC, had gearing which was able to approximate the moons path through the heavens. Epicyclic gearing or planetary gearing is a system consisting of one or more outer gears, or planet gears, revolving about a central. Typically, the gears are mounted on a movable arm or carrier. Epicyclic gearing systems also incorporate the use of a ring gear or annulus. Planetary gears are classified as simple or compound planetary gears. Simple planetary gears have one sun, one ring, one carrier, Compound planetary gears involve one or more of the following three types of structures, meshed-planet, stepped-planet, and multi-stage structures. Compared to simple planetary gears, compound planetary gears have the advantages of larger reduction ratio, higher torque-to-weight ratio, and more flexible configurations
Epicyclic gearing
–
Bookwheel, from Agostino Ramelli's Le diverse et artifiose machine, 1588
Epicyclic gearing
–
This planetary gear train consists of a sun gear (yellow), planet gears (blue) supported by the carrier (green) and an annular gear (pink). The red marks show the relative displacement of the sun gear and carrier, when the carrier is rotated 45° clockwise and the annular gear is held fixed.
Epicyclic gearing
–
Compound planets of a
Sturmey-Archer AM bicycle hub (gear ring removed)
Epicyclic gearing
–
A spur gear differential constructed by engaging the planet gears of two co-axial epicyclic gear trains. The casing is the carrier for this planetary gear train.
14.
Program (machine)
–
A program is a set of instructions used to control the behavior of a machine, often a computer. Examples of programs include, The sequence of cards used by a Jacquard loom to produce a pattern within weaved cloth. Invented in 1801, it used holes in punched cards to represent sewing loom arm movements in order to generate decorative patterns automatically, a computer program list of instructions to be executed by a computer. Barrels, punched cards and music rolls encoding music to be played by player pianos, fairground organs, barrel organs, the execution of a program is a series of actions following the instructions it contains. Each instruction produces effects that alter the state of the according to its predefined meaning
Program (machine)
–
Lovelace's diagram from Note G, the
first published computer algorithm
Program (machine)
–
Switches for manual input on a
Data General Nova 3, manufactured in the mid 1970s
Program (machine)
–
In the 1950s, computer programs were stored on
perforated paper tape
Program (machine)
–
The
microcontroller on the right of this
USB flash drive is controlled with embedded
firmware.
15.
Europe
–
Europe is a continent that comprises the westernmost part of Eurasia. Europe is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, yet the non-oceanic borders of Europe—a concept dating back to classical antiquity—are arbitrary. Europe covers about 10,180,000 square kilometres, or 2% of the Earths surface, politically, Europe is divided into about fifty sovereign states of which the Russian Federation is the largest and most populous, spanning 39% of the continent and comprising 15% of its population. Europe had a population of about 740 million as of 2015. Further from the sea, seasonal differences are more noticeable than close to the coast, Europe, in particular ancient Greece, was the birthplace of Western civilization. The fall of the Western Roman Empire, during the period, marked the end of ancient history. Renaissance humanism, exploration, art, and science led to the modern era, from the Age of Discovery onwards, Europe played a predominant role in global affairs. Between the 16th and 20th centuries, European powers controlled at times the Americas, most of Africa, Oceania. The Industrial Revolution, which began in Great Britain at the end of the 18th century, gave rise to economic, cultural, and social change in Western Europe. During the Cold War, Europe was divided along the Iron Curtain between NATO in the west and the Warsaw Pact in the east, until the revolutions of 1989 and fall of the Berlin Wall. In 1955, the Council of Europe was formed following a speech by Sir Winston Churchill and it includes all states except for Belarus, Kazakhstan and Vatican City. Further European integration by some states led to the formation of the European Union, the EU originated in Western Europe but has been expanding eastward since the fall of the Soviet Union in 1991. The European Anthem is Ode to Joy and states celebrate peace, in classical Greek mythology, Europa is the name of either a Phoenician princess or of a queen of Crete. The name contains the elements εὐρύς, wide, broad and ὤψ eye, broad has been an epithet of Earth herself in the reconstructed Proto-Indo-European religion and the poetry devoted to it. For the second part also the divine attributes of grey-eyed Athena or ox-eyed Hera. The same naming motive according to cartographic convention appears in Greek Ανατολή, Martin Litchfield West stated that phonologically, the match between Europas name and any form of the Semitic word is very poor. Next to these there is also a Proto-Indo-European root *h1regʷos, meaning darkness. Most major world languages use words derived from Eurṓpē or Europa to refer to the continent, in some Turkic languages the originally Persian name Frangistan is used casually in referring to much of Europe, besides official names such as Avrupa or Evropa
Europe
–
Reconstruction of
Herodotus ' world map
Europe
Europe
–
A medieval
T and O map from 1472 showing the three continents as domains of the sons of
Noah — Asia to Sem (
Shem), Europe to Iafeth (
Japheth), and Africa to Cham (
Ham)
Europe
–
Early modern depiction of
Europa regina ('Queen Europe') and the mythical
Europa of the 8th century BC.
16.
Korea
–
Korea is a historical state in East Asia, since 1945 divided into two distinct sovereign states, North Korea and South Korea. Located on the Korean Peninsula, Korea is bordered by China to the northwest and it is separated from Japan to the east by the Korea Strait and the Sea of Japan. Korea emerged as a political entity after centuries of conflict among the Three Kingdoms of Korea. Later Silla divided into three states during the Later Three Kingdoms period. Goryeo, which had succeeded Goguryeo, defeated the two states and united the Korean Peninsula. Around the same time, Balhae collapsed and its last crown prince fled south to Goryeo, Goryeo, whose name developed into the modern exonym Korea, was a highly cultured state that created the worlds first metal movable type in 1234. However, multiple invasions by the Mongol Yuan Dynasty during the 13th century greatly weakened the nation, following the Yuan Dynastys collapse, severe political strife followed, and Goryeo eventually fell to a coup led by General Yi Seong-gye, who established Joseon in 1388. The first 200 years of Joseon were marked by peace and saw the creation of the Korean alphabet by Sejong the Great in the 14th century. During the later part of the dynasty, however, Koreas isolationist policy earned it the Western nickname of the Hermit Kingdom, by the late 19th century, the country became the object of imperial design by the Empire of Japan. Despite attempts at modernization by the Korean Empire, in 1910 Korea was annexed by Japan and these circumstances soon became the basis for the division of Korea by the two superpowers, exacerbated by their incapability to agree on the terms of Korean independence. To date, both continue to compete with each other as the sole legitimate government of all of Korea. Korea is the spelling of Corea, a name attested in English as early as 1614. It is a derived from Cauli, Marco Polos transcription of the Chinese 高麗. This was the Hanja for the Korean kingdom of Goryeo or Koryŏ, Goryeos name was a continuation of the earlier Goguryeo or Koguryŏ, the northernmost of the Samguk, which was officially known by the shortened form Goryeo after the 5th-century reign of King Jangsu. The original name was a combination of the go with the name of a local Yemaek tribe. The name Korea is now used in English contexts by both North and South Korea. In South Korea, Korea as a whole is referred to as Hanguk, the name references the Samhan—Ma, Jin, and Byeon—who preceded the Three Kingdoms in the southern and central end of the peninsula during the 1st centuries BC and AD. It has been linked with the title khan used by the nomads of Manchuria
Korea
Korea
–
Anapji (Anap Pond) in
Gyeongju Historic Areas.
Korea
–
The
Gyeongbokgung Palace
17.
Japan
–
Japan is a sovereign island nation in Eastern Asia. Located in the Pacific Ocean, it lies off the eastern coast of the Asia Mainland and stretches from the Sea of Okhotsk in the north to the East China Sea, the kanji that make up Japans name mean sun origin. 日 can be read as ni and means sun while 本 can be read as hon, or pon, Japan is often referred to by the famous epithet Land of the Rising Sun in reference to its Japanese name. Japan is an archipelago consisting of about 6,852 islands. The four largest are Honshu, Hokkaido, Kyushu and Shikoku, the country is divided into 47 prefectures in eight regions. Hokkaido being the northernmost prefecture and Okinawa being the southernmost one, the population of 127 million is the worlds tenth largest. Japanese people make up 98. 5% of Japans total population, approximately 9.1 million people live in the city of Tokyo, the capital of Japan. Archaeological research indicates that Japan was inhabited as early as the Upper Paleolithic period, the first written mention of Japan is in Chinese history texts from the 1st century AD. Influence from other regions, mainly China, followed by periods of isolation, from the 12th century until 1868, Japan was ruled by successive feudal military shoguns who ruled in the name of the Emperor. Japan entered into a period of isolation in the early 17th century. The Second Sino-Japanese War of 1937 expanded into part of World War II in 1941, which came to an end in 1945 following the bombings of Hiroshima and Nagasaki. Japan is a member of the UN, the OECD, the G7, the G8, the country has the worlds third-largest economy by nominal GDP and the worlds fourth-largest economy by purchasing power parity. It is also the worlds fourth-largest exporter and fourth-largest importer, although Japan has officially renounced its right to declare war, it maintains a modern military with the worlds eighth-largest military budget, used for self-defense and peacekeeping roles. Japan is a country with a very high standard of living. Its population enjoys the highest life expectancy and the third lowest infant mortality rate in the world, in ancient China, Japan was called Wo 倭. It was mentioned in the third century Chinese historical text Records of the Three Kingdoms in the section for the Wei kingdom, Wa became disliked because it has the connotation of the character 矮, meaning dwarf. The 倭 kanji has been replaced with the homophone Wa, meaning harmony, the Japanese word for Japan is 日本, which is pronounced Nippon or Nihon and literally means the origin of the sun. The earliest record of the name Nihon appears in the Chinese historical records of the Tang dynasty, at the start of the seventh century, a delegation from Japan introduced their country as Nihon
Japan
–
The
Golden Hall and
five-storey pagoda of
Hōryū-ji, among the oldest wooden buildings in the world,
National Treasures, and a
UNESCO World Heritage Site
Japan
Japan
–
Samurai warriors face Mongols, during the
Mongol invasions of Japan. The
Kamikaze, two storms, are said to have saved Japan from Mongol fleets.
Japan
–
Samurai could
kill a commoner for the slightest insult and were widely feared by the Japanese population.
Edo period, 1798
18.
Sundial
–
A sundial is a device that tells the time of day by the apparent position of the Sun in the sky. In the narrowest sense of the word it consists of a flat plate, as the sun appears to move across the sky, the shadow aligns with different hour-lines which are marked on the dial to indicate the time of day. The style is the edge of the gnomon, though a single point or nodus may be used. The gnomon casts a shadow, the shadow of the style shows the time. The gnomon may be a rod, a wire or a decorated metal casting. The style must be parallel to the axis of the Earths rotation for the sundial to be throughout the year. The styles angle from horizontal is equal to the geographical latitude. In a broader sense a sundial is any device that uses the suns altitude or azimuth to show the time, in addition to their time-telling function, sundials are valued as decorative objects, as literary metaphors and as objects of mathematical study. It is common for inexpensive mass-produced decorative sundials to have incorrectly aligned gnomons and hour-lines, there are several different types of sundials. Some sundials use a shadow or the edge of a shadow while others use a line or spot of light to indicate the time, the shadow-casting object, known as a gnomon, may be a long thin rod or other object with a sharp tip or a straight edge. Sundials employ many types of gnomon, the gnomon may be fixed or moved according to the season. It may be oriented vertically, horizontally, aligned with the Earths axis, given that sundials use light to indicate time, a line of light may be formed by allowing the suns rays through a thin slit or focusing them through a cylindrical lens. A spot of light may be formed by allowing the suns rays to pass through a hole or by reflecting them from a small circular mirror. Sundials also may use many types of surfaces to receive the light or shadow, planes are the most common surface, but partial spheres, cylinders, cones and other shapes have been used for greater accuracy or beauty. Sundials differ in their portability and their need for orientation, the installation of many dials requires knowing the local latitude, the precise vertical direction, and the direction to true North. Portable dials are self-aligning, for example, it may have two dials that operate on different principles, such as a horizontal and analemmatic dial, mounted together on one plate, in these designs, their times agree only when the plate is aligned properly. Sundials indicate the solar time, unless corrected for some other time. To obtain the clock time, three types of corrections need to be made
Sundial
–
SSW facing, vertical declining sundial on Moot Hall,
Aldeburgh, Suffolk, England.
Sundial
–
A combined analemmatic-equatorial sundial in Ann Morrison Park in
Boise, Idaho, 43°36'45.5"N 116°13'27.6"W
Sundial
–
Sundial in
Singapore Botanic Gardens. The fact that
Singapore is located almost at the
equator is reflected in its design.
Sundial
–
World's oldest sundial, from Egypt's Valley of the Kings (c. 1500 BC)
19.
Pendulum clock
–
A pendulum clock is a clock that uses a pendulum, a swinging weight, as its timekeeping element. The advantage of a pendulum for timekeeping is that it is an oscillator, it swings back and forth in a precise time interval dependent on its length. From its invention in 1656 by Christiaan Huygens until the 1930s, Pendulum clocks must be stationary to operate, any motion or accelerations will affect the motion of the pendulum, causing inaccuracies, so other mechanisms must be used in portable timepieces. They are now mostly for their decorative and antique value. The pendulum clock was invented in 1656 by Dutch scientist and inventor Christiaan Huygens, Huygens contracted the construction of his clock designs to clockmaker Salomon Coster, who actually built the clock. Huygens was inspired by investigations of pendulums by Galileo Galilei beginning around 1602, Galileo discovered the key property that makes pendulums useful timekeepers, isochronism, which means that the period of swing of a pendulum is approximately the same for different sized swings. Galileo had the idea for a clock in 1637, which was partly constructed by his son in 1649. These early clocks, due to their verge escapements, had wide pendulum swings of up to 100°, clockmakers realization that only pendulums with small swings of a few degrees are isochronous motivated the invention of the anchor escapement around 1670, which reduced the pendulums swing to 4–6°. The anchor became the standard escapement used in pendulum clocks, in addition to increased accuracy, the anchors narrow pendulum swing allowed the clocks case to accommodate longer, slower pendulums, which needed less power and caused less wear on the movement. The seconds pendulum,0.994 m long, in which each swing takes one second, the long narrow clocks built around these pendulums, first made by William Clement around 1680, became known as grandfather clocks. The increased accuracy resulting from these developments caused the hand, previously rare. The 18th and 19th century wave of innovation that followed the invention of the pendulum brought many improvements to pendulum clocks. Observation that pendulum clocks slowed down in summer brought the realization that thermal expansion and contraction of the rod with changes in temperature was a source of error. This was solved by the invention of temperature-compensated pendulums, the pendulum by George Graham in 1721. With these improvements, by the mid-18th century precision pendulum clocks achieved accuracies of a few seconds per week, until the 19th century, clocks were handmade by individual craftsmen and were very expensive. The rich ornamentation of pendulum clocks of this period indicates their value as symbols of the wealthy. The clockmakers of each country and region in Europe developed their own distinctive styles, by the 19th century, factory production of clock parts gradually made pendulum clocks affordable by middle-class families. During the Industrial Revolution, daily life was organized around the pendulum clock
Pendulum clock
–
Pendulum clock conceived by
Galileo Galilei around 1637. The earliest known pendulum clock design, it was never completed.
Pendulum clock
–
Vienna regulator style pendulum wall clock
Pendulum clock
–
A
lantern clock that has been converted to use a pendulum. To accommodate the wide pendulum swings caused by the
verge escapement, "wings" have been added on the sides
Pendulum clock
–
Mantel clock (around 1800) by Julien Béliard,
Paris, maître horloger recorded on the rue Saint-Benôit and rue Pavée in 1777, still active in 1817, or Julien-Antoine Béliard, maître horloger in 1786, recorded on the rue de Hurepoix, 1787–1806.
20.
Su Song
–
Su Song was the engineer of a hydro-mechanical astronomical clock tower in medieval Kaifeng, which employed the use of an early escapement mechanism. Sus clock tower featured the oldest known endless power-transmitting chain drive, called the tian ti, or celestial ladder. The clock tower had 133 different clock jacks to indicate and sound the hours, Su Songs treatise about the clock tower, Xinyi Xiangfayao, has survived since its written form in 1092 and official printed publication in 1094. The book has been analyzed by historians, such as Joseph Needham. The clock itself, however, was dismantled by the invading Jurchen army in AD1127, and although attempts were made to reassemble it, the Xinyi Xiangfayao was Sus best-known treatise, but the polymath compiled other works as well. He completed a large celestial atlas of several maps, several terrestrial maps. The latter discussed related subjects on mineralogy, zoology, botany and they thought that advanced mechanical clockworks were new to China and that these mechanisms were something valuable that Europeans could offer to the Chinese. Su Song was a Hokkien who was born in modern-day Fujian, like a contemporary, Shen Kuo, Su Song was a polymath, a person whose expertise spans a significant number of different interests. From an early age, his interests in astronomy and calendrical science led him onto a path as a state bureaucrat. In his spare time he was fond of writing poetry, which he used to praise the works of such as the painter Li Gonglin. He also was an antiquarian and collector of old artworks from previous dynasties, after serving in the Ministry of Personnel, he became a Minister of Justice in 1086. Eventually, Su rose to the post of Vice President of the Chancellery Secretariat, among many honorable positions and titles conferred upon him, Su Song was also one of the Deputy Tutors of the Heir Apparent. Historian Liu Heping states that Emperor Zhezong of Song sponsored Su Songs clocktower in 1086 in order to compete with the Liao for scientific and national superiority. In 1081, the court instructed Su Song to compile into a book the diplomatic history of Song-Liao relations, with his extensive knowledge of cartography, Su Song was able to settle a heated border dispute between the Song and Liao dynasties. Furthermore, Su Song must have taken advantage of the findings of his political rival. There were many star maps written before Songs book, but the greatest significance of these star maps by Su Song is, that they represent the oldest extant star maps in printed form. In 1070, Su Song and a team of scholars compiled and edited the Bencao Tujing, which was a treatise on pharmaceutical botany, zoology. In compiling information for pharmaceutical knowledge, Su Song worked with such scholars as Zhang Yuxi, Lin Yi, Zhang Dong
Su Song
–
蘇頌 (Sū Sòng)
Su Song
–
The original diagram of Su's book showing the inner workings of his clocktower, for more information, click this thumbnail picture.
Su Song
–
A
scale model of Su Song's Astronomical Clock Tower
Su Song
–
A
star map with equidistant cylindrical projection, from Su Song's Xinyi Xiangfayao, 1092
21.
Waterwheel
–
A water wheel is a machine for converting the energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a wheel, with a number of blades or buckets arranged on the outside rim forming the driving surface. Most commonly, the wheel is mounted vertically on a horizontal axle, vertical wheels can transmit power either through the axle or via a ring gear and typically drive belts or gears, horizontal wheels usually directly drive their load. Water wheels were still in use well into the 20th century. Uses included milling flour in gristmills, grinding wood into pulp for papermaking, hammering wrought iron, machining, some water wheels are fed by water from a mill pond, which is formed when a flowing stream is dammed. A channel for the water flowing to or from a wheel is called a mill race. The race bringing water from the pond to the water wheel is a headrace. In the mid to late 18th century John Smeatons scientific investigation of the water led to significant increases in efficiency supplying much needed power for the Industrial Revolution. Water wheels began being displaced by the smaller, less expensive and more efficient turbine, developed by Benoît Fourneyron, turbines are capable of handling high heads, or elevations, that exceed the capability of practical-sized waterwheels. The main difficulty of water wheels is their dependence on flowing water, modern hydroelectric dams can be viewed as the descendants of the water wheel, as they too take advantage of the movement of water downhill. The two main functions of water wheels were historically water-lifting for irrigation purposes and as a power source, when used for water-lifting power can be supplied by either human or animal force or by the water current itself. Water wheels come in two designs, either a vertical or a horizontal axle. The latter type can be subdivided, depending on where the hits the wheel. Engineers of the Hellenistic era Mediterranean region are credited with the development of the water wheel, Mediterranean engineers of the Hellenistic and Roman periods were also the first to use it for both irrigation and as a power source. The technological breakthrough occurred in the advanced and scientifically minded Hellenistic period between the 3rd and 1st centuries BCE. This is seen as an evolution of the paddle-driven water-lifting wheels that had appeared in ancient Egypt by the 4th century BCE. According to John Peter Oleson, both the wheel and the hydraulic Noria appeared in Egypt by the 4th century BCE. This is supported by finds at Faiyum, where the oldest archeological evidence of a water-wheel has been found
Waterwheel
–
An overshot waterwheel standing 42 ft (13 m) high powers the Old Mill at
Berry College in
Rome, Georgia, USA
Waterwheel
–
Water wheel powering a
mine hoist in
De re metallica (1566)
Waterwheel
–
Sequence of wheels found in
Rio Tinto mines, southwestern Spain
Waterwheel
–
Reconstruction of
Vitruvius ' undershot-wheeled watermill
22.
Chain drive
–
Chain drive is a way of transmitting mechanical power from one place to another. It is often used to power to the wheels of a vehicle. It is also used in a variety of machines besides vehicles. The gear is turned, and this pulls the chain putting mechanical force into the system, another type of drive chain is the Morse chain, invented by the Morse Chain Company of Ithaca, New York, United States. Sometimes the power is output by simply rotating the chain, which can be used to lift or drag objects, in other situations, a second gear is placed and the power is recovered by attaching shafts or hubs to this gear. By varying the diameter of the input and output gears with respect to each other, for example, when the bicycle pedals gear rotate once, it causes the gear that drives the wheels to rotate more than one revolution. The oldest known application of a chain appears in the Polybolos. Two flat-linked chains were connected to a windlass, which by winding back and it is here that the flat-link chain, often attributed to Leonardo da Vinci, actually made its first appearance. The chain drive itself was given power via the works of Sus water clock tank and waterwheel. Roller chain and sprockets is an efficient method of power transmission compared to belts. Although chains can be stronger than belts, their greater mass increases drive train inertia. Drive chains are most often made of metal, while belts are often rubber, plastic, urethane, or other substances. Drive belts can slip unless they have teeth, which means that the side may not rotate at a precise speed. Wear on rubber or plastic belts and their teeth is often easier to observe, one problem with roller chains is the variation in speed, or surging, caused by the acceleration and deceleration of the chain as it goes around the sprocket link by link. It starts as soon as the line of the chain contacts the first tooth of the sprocket. This contact occurs at a point below the circle of the sprocket. As the sprocket rotates, the chain is raised up to the circle and is then dropped down again as sprocket rotation continues. This rising and falling of the line is what causes chordal effect or speed variation
Chain drive
–
Sketch of
roller chain by
Leonardo da Vinci
Chain drive
–
Roller chain and
sprocket
Chain drive
–
Chain final drive, 1912 illustration
Chain drive
–
Mack AC delivery truck at the
Petersen Automotive Museum with chain drive visible
23.
Armillary sphere
–
As such, it differs from a celestial globe, which is a smooth sphere whose principal purpose is to map the constellations. It was invented separately in ancient Greece and ancient China, with use in the Islamic world. With the Earth as center, a sphere is known as Ptolemaic. With the sun as center, it is known as Copernican, the flag of Portugal features an armillary sphere. The armillary sphere is also featured in Portuguese heraldry, associated with the Portuguese discoveries during the Age of Exploration and this section refers to labels in the diagram below. The exterior parts of machine are a compages of brass rings. The equinoctial A, which is divided into 360 degrees for showing the right ascension in degrees. The Arctic Circle E, and the Antarctic Circle F, each 23½ degrees from its respective pole at N and S.5. The equinoctial colure G, passing through the north and south poles of the heaven at N and S, the solstitial colure H, passing through the poles of the heaven, and through the solstitial points Cancer and Capricorn, in the ecliptic. Within these circular rings is a terrestrial globe J, fixed on an axis K. On this axis is fixed the flat celestial meridian L L and this flat meridian is graduated the same way as the brass meridian of the common globe, and its use is much the same. The globe may be turned by hand within this ring, so as to any given meridian upon it. The horizon is divided into 360 degrees all around its outermost edge, within which are the points of the compass, for showing the amplitude of the sun and the moon, both in degrees and points. The celestial meridian L passes through two notches in the north and south points of the horizon, as in a common globe, both here, if the globe be turned round, the horizon and meridian turn with it. At the south pole of the sphere is a circle of 25 hours, fixed to the rings, in the box T are two wheels and two pinions, whose axes come out at V and U, either of which may be turned by the small winch W. If the earthly globe be turned, the hour-index goes round its hour-circle, but if the sphere be turned, and so, by this construction, the machine is equally fitted to show either the real motion of the earth, or the apparent motion of the heaven. — Then turn the winch, and observe when the sun or moon rise and set in the horizon, throughout Chinese history, astronomers have created celestial globes to assist the observation of the stars. The Chinese also used the sphere in aiding calendrical computations and calculations
Armillary sphere
–
Jost Bürgi and
Antonius Eisenhoit: Armillary sphere with
astronomical clock, made in 1585 in
Kassel, now at
Nordiska Museet in Stockholm
Armillary sphere
–
The original diagram of
Su Song 's book of 1092 showing the inner workings of his
clocktower; a
mechanically-rotated armillary sphere crowns the top.
Armillary sphere
–
Celestial globe from the
Qing Dynasty
Armillary sphere
–
The spherical
astrolabe from medieval
Islamic astronomy
24.
Striking clock
–
A striking clock is a clock that sounds the hours audibly on a bell or gong. The striking feature of clocks was originally more important than their faces, the earliest clocks struck the hours. The development of clocks in Europe was motivated by the need to ring bells upon the canonical hours to call the community to prayer. The earliest known mechanical clocks were striking clocks installed in towers in monasteries or public squares. As the modern 12-hour clock became more widespread, particularly in Great Britain and Northern Europe, 12-hour striking became more widespread, in addition to striking on the hour, many striking clocks play sequences of chimes on the quarter-hours. The most common sequence is Westminster Quarters, today the time-disseminating functions of clock striking are almost totally unnecessary, and striking clocks are kept for historical, traditional, and aesthetic reasons. Historic clock towers in towns, universities, and religious institutions worldwide still strike the hours, famous examples being Big Ben in London, home striking clocks, such as mantel clocks, cuckoo clocks, and grandfather clocks are also common. The most basic sort of striking clock simply sounds a bell every hour. This sort of striking clock is called a passing strike clock. It is far simpler to create such a clock, all that must be done is to attach a cam to a shaft that rotates once an hour and this sort of striking is still found in some skeleton clocks. It does not require a separate train to arm and release the single stroke sounded. The Tang Dynasty Chinese Buddhist monk and inventor Yi Xing created a rotating globe that was given motive power by hydraulics of a turning waterwheel. This featured two wooden gear jacks on its surface with a drum and a bell, the bell being struck automatically every hour. It is recorded that Confucian students in the year 730 were required to write an essay on this device in order to pass the Imperial examinations. The use of jacks to sound the hours were used in later clock towers of Song Dynasty China, such as those designed by Zhang Sixun and Su Song in the 10th and 11th centuries. A striking clock outside of China was the tower near the Umayyad Mosque in Damascus, Syria. It was constructed by the Arab engineer al-Kaysarani in 1154, the Florentine writer Dante Alighieri made a reference to the gear works of striking clocks in 1319. The most famous original striking clock tower still standing is possibly the one in St Marks Clocktower in St Marks Square, Venice
Striking clock
–
The Elizabeth Tower of the
Palace of Westminster in
London, commonly referred to as
Big Ben, is a famous striking clock.
25.
Astronomy
–
Astronomy is a natural science that studies celestial objects and phenomena. It applies mathematics, physics, and chemistry, in an effort to explain the origin of those objects and phenomena and their evolution. Objects of interest include planets, moons, stars, galaxies, and comets, while the phenomena include supernovae explosions, gamma ray bursts, more generally, all astronomical phenomena that originate outside Earths atmosphere are within the purview of astronomy. A related but distinct subject, physical cosmology, is concerned with the study of the Universe as a whole, Astronomy is the oldest of the natural sciences. The early civilizations in recorded history, such as the Babylonians, Greeks, Indians, Egyptians, Nubians, Iranians, Chinese, during the 20th century, the field of professional astronomy split into observational and theoretical branches. Observational astronomy is focused on acquiring data from observations of astronomical objects, theoretical astronomy is oriented toward the development of computer or analytical models to describe astronomical objects and phenomena. The two fields complement each other, with theoretical astronomy seeking to explain the results and observations being used to confirm theoretical results. Astronomy is one of the few sciences where amateurs can play an active role, especially in the discovery. Amateur astronomers have made and contributed to many important astronomical discoveries, Astronomy means law of the stars. Astronomy should not be confused with astrology, the system which claims that human affairs are correlated with the positions of celestial objects. Although the two share a common origin, they are now entirely distinct. Generally, either the term astronomy or astrophysics may be used to refer to this subject, however, since most modern astronomical research deals with subjects related to physics, modern astronomy could actually be called astrophysics. Few fields, such as astrometry, are purely astronomy rather than also astrophysics, some titles of the leading scientific journals in this field includeThe Astronomical Journal, The Astrophysical Journal and Astronomy and Astrophysics. In early times, astronomy only comprised the observation and predictions of the motions of objects visible to the naked eye, in some locations, early cultures assembled massive artifacts that possibly had some astronomical purpose. Before tools such as the telescope were invented, early study of the stars was conducted using the naked eye, most of early astronomy actually consisted of mapping the positions of the stars and planets, a science now referred to as astrometry. From these observations, early ideas about the motions of the planets were formed, and the nature of the Sun, Moon, the Earth was believed to be the center of the Universe with the Sun, the Moon and the stars rotating around it. This is known as the model of the Universe, or the Ptolemaic system. The Babylonians discovered that lunar eclipses recurred in a cycle known as a saros
Astronomy
–
A
star -forming region in the
Large Magellanic Cloud, an
irregular galaxy.
Astronomy
–
A giant
Hubble mosaic of the
Crab Nebula, a
supernova remnant
Astronomy
–
19th century
Sydney Observatory,
Australia (1873)
Astronomy
–
19th century
Quito Astronomical Observatory is located 12 minutes south of the
Equator in
Quito,
Ecuador.
26.
Astrology
–
Astrology is the study of the movements and relative positions of celestial objects as a means for divining information about human affairs and terrestrial events. Throughout most of its history astrology was considered a tradition and was common in academic circles, often in close relation with astronomy, alchemy, meteorology. It was present in political circles, and is mentioned in works of literature, from Dante Alighieri and Geoffrey Chaucer to William Shakespeare, Lope de Vega. Astrology thus lost its academic and theoretical standing, and common belief in it has largely declined, Astrology is now recognized to be pseudoscience. The word astrology comes from the early Latin word astrologia, which derives from the Greek ἀστρολογία—from ἄστρον astron, astrologia later passed into meaning star-divination with astronomia used for the scientific term. Many cultures have attached importance to astronomical events, and the Indians, Chinese, the majority of professional astrologers rely on such systems. Astrology has been dated to at least the 2nd millennium BCE, with roots in systems used to predict seasonal shifts. A form of astrology was practised in the first dynasty of Mesopotamia, Chinese astrology was elaborated in the Zhou dynasty. Hellenistic astrology after 332 BCE mixed Babylonian astrology with Egyptian Decanic astrology in Alexandria, Alexander the Greats conquest of Asia allowed astrology to spread to Ancient Greece and Rome. In Rome, astrology was associated with Chaldean wisdom, after the conquest of Alexandria in the 7th century, astrology was taken up by Islamic scholars, and Hellenistic texts were translated into Arabic and Persian. In the 12th century, Arabic texts were imported to Europe, major astronomers including Tycho Brahe, Johannes Kepler and Galileo practised as court astrologers. Astrological references appear in literature in the works of such as Dante Alighieri and Geoffrey Chaucer. Throughout most of its history, astrology was considered a scholarly tradition and it was accepted in political and academic contexts, and was connected with other studies, such as astronomy, alchemy, meteorology, and medicine. At the end of the 17th century, new concepts in astronomy. Astrology thus lost its academic and theoretical standing, and common belief in astrology has largely declined, Astrology, in its broadest sense, is the search for meaning in the sky. This was a first step towards recording the Moons influence upon tides and rivers, by the 3rd millennium BCE, civilisations had sophisticated awareness of celestial cycles, and may have oriented temples in alignment with heliacal risings of the stars. Scattered evidence suggests that the oldest known references are copies of texts made in the ancient world. The Venus tablet of Ammisaduqa thought to be compiled in Babylon around 1700 BCE, a scroll documenting an early use of electional astrology is doubtfully ascribed to the reign of the Sumerian ruler Gudea of Lagash
Astrology
Astrology
–
Marcantonio Raimondi engraving, 15th century
Astrology
–
'The Zodiac Man' a diagram of a human body and astrological symbols with instructions explaining the importance of astrology from a medical perspective. From a 15th century Welsh manuscript
Astrology
–
The Roman orator
Cicero objected to astrology.
27.
Ming Dynasty
–
The Ming dynasty was the ruling dynasty of China – then known as the Empire of the Great Ming – for 276 years following the collapse of the Mongol-led Yuan dynasty. The Ming, described by some as one of the greatest eras of orderly government, although the primary capital of Beijing fell in 1644 to a rebellion led by Li Zicheng, regimes loyal to the Ming throne – collectively called the Southern Ming – survived until 1683. He rewarded his supporters and employed them as a counterweight against the Confucian scholar-bureaucrats. One, Zheng He, led seven enormous voyages of exploration into the Indian Ocean as far as Arabia, the rise of new emperors and new factions diminished such extravagances, the capture of the Zhengtong Emperor during the 1449 Tumu Crisis ended them completely. The imperial navy was allowed to fall into disrepair while forced labor constructed the Liaodong palisade, haijin laws intended to protect the coasts from Japanese pirates instead turned many into smugglers and pirates themselves. The growth of Portuguese, Spanish, and Dutch trade created new demand for Chinese products and produced an influx of Japanese. This abundance of specie remonetized the Ming economy, whose money had suffered repeated hyperinflation and was no longer trusted. While traditional Confucians opposed such a prominent role for commerce and the newly rich it created, combined with crop failure, floods, and epidemic, the dynasty collapsed before the rebel leader Li Zicheng, who was defeated by the Manchu-led Eight Banner armies who founded the Qing dynasty. The Mongol-led Yuan dynasty ruled before the establishment of the Ming dynasty, consequently, agriculture and the economy were in shambles, and rebellion broke out among the hundreds of thousands of peasants called upon to work on repairing the dykes of the Yellow River. A number of Han Chinese groups revolted, including the Red Turbans in 1351, the Red Turbans were affiliated with the White Lotus, a Buddhist secret society. Zhu Yuanzhang was a peasant and Buddhist monk who joined the Red Turbans in 1352. In 1356, Zhus rebel force captured the city of Nanjing, with the Yuan dynasty crumbling, competing rebel groups began fighting for control of the country and thus the right to establish a new dynasty. In 1363, Zhu Yuanzhang eliminated his archrival and leader of the rebel Han faction, Chen Youliang, in the Battle of Lake Poyang, arguably the largest naval battle in history. Known for its ambitious use of ships, Zhus force of 200,000 Ming sailors were able to defeat a Han rebel force over triple their size, claimed to be 650. The victory destroyed the last opposing rebel faction, leaving Zhu Yuanzhang in uncontested control of the bountiful Yangtze River Valley, Zhu Yuanzhang took Hongwu, or Vastly Martial, as his era name. Hongwu made an effort to rebuild state infrastructure. He built a 48 km long wall around Nanjing, as well as new palaces, Hongwu organized a military system known as the weisuo, which was similar to the fubing system of the Tang dynasty. With a growing suspicion of his ministers and subjects, Hongwu established the Jinyiwei, some 100,000 people were executed in a series of purges during his rule
Ming Dynasty
–
History of China
Ming Dynasty
–
Ming China around 1580
Ming Dynasty
–
A
cannon from the
Huolongjing, compiled by
Jiao Yu and
Liu Bowen before the latter's death in 1375.
Ming Dynasty
–
Portrait of the
Hongwu Emperor (ruled in 1368–98)
28.
Zhang Heng
–
Zhang Heng, formerly romanized as Chang Heng, was a Han Chinese polymath from Nanyang who lived during the Han dynasty. Zhang Heng began his career as a civil servant in Nanyang. Eventually, he became Chief Astronomer, Prefect of the Majors for Official Carriages and his uncompromising stance on historical and calendrical issues led to his becoming a controversial figure, preventing him from rising to the status of Grand Historian. His political rivalry with the palace eunuchs during the reign of Emperor Shun led to his decision to retire from the court to serve as an administrator of Hejian in Hebei. Zhang returned home to Nanyang for a time, before being recalled to serve in the capital once more in 138. He died there a year later, in 139, Zhang applied his extensive knowledge of mechanics and gears in several of his inventions. He improved previous Chinese calculations for pi and his fu and shi poetry were renowned in his time and studied and analyzed by later Chinese writers. Zhang received many honors for his scholarship and ingenuity, some modern scholars have compared his work in astronomy to that of the Greco-Roman Ptolemy. Born in the town of Xie in Nanyang Commandery, Zhang Heng came from a distinguished, at age ten, Zhangs father died, leaving him in the care of his mother and grandmother. An accomplished writer in his youth, Zhang left home in the year 95 to pursue his studies in the capitals of Changan, while traveling to Luoyang, Zhang passed by a hot spring near Mount Li and dedicated one of his earliest fu poems to it. Government authorities offered Zhang appointments to offices, including a position as one of the Imperial Secretaries, yet he acted modestly. At age twenty-three, he returned home with the title Officer of Merit in Nanyang, serving as the master of documents under the administration of Governor Bao De, as he was charged with composing inscriptions and dirges for the governor, he gained experience in writing official documents. As Officer of Merit in the commandery, he was responsible for local appointments to office. He spent much of his time composing rhapsodies on the capital cities, when Bao De was recalled to the capital in 111 to serve as a minister of finance, Zhang continued his literary work at home in Xie. Zhang Heng began his studies in astronomy at the age of thirty and began publishing his works on astronomy, in 112, Zhang was summoned to the court of Emperor An, who had heard of his expertise in mathematics. When he was nominated to serve at the capital, Zhang was escorted by carriage—a symbol of his official status—to Luoyang and he was promoted to Chief Astronomer for the court, serving his first term from 115–120 under Emperor An and his second under the succeeding emperor from 126–132. As Chief Astronomer, Zhang was a subordinate of the Minister of Ceremonies, when the government official Dan Song proposed the Chinese calendar should be reformed in 123 to adopt certain apocryphal teachings, Zhang opposed the idea. He considered the teachings to be of questionable stature and believed they could introduce errors, others shared Zhangs opinion and the calendar was not altered, yet Zhangs proposal that apocryphal writings should be banned was rejected
Zhang Heng
–
A stamp of Zhang Heng issued by
China Post in 1955
Zhang Heng
–
A 2nd-century
lacquer-painted scene on a basket box showing famous figures from Chinese history who were paragons of
filial piety: Zhang Heng became well-versed at an early age in the
Chinese classics and the
philosophy of China's earlier sages.
Zhang Heng
–
A Western Han
terracotta cavalier figurine wearing robes and a hat. As Chief Astronomer, Zhang Heng earned a fixed salary and rank of 600 bushels of grain (which was mostly commuted to payments in
coinage currency or bolts of
silk), and so he would have worn a specified type of robe, ridden in a specified type of carriage, and held a unique emblem that marked his status in the official hierarchy.
Zhang Heng
–
A pottery miniature
of a palace made during the Han Dynasty; as a palace attendant, Zhang Heng had personal access to Emperor Shun and the right to escort him
29.
Pressure head
–
In fluid mechanics, pressure head is the internal energy of a fluid due to the pressure exerted on its container. It may also be called static pressure head or simply static head, pressure head is a component of hydraulic head, in which it is combined with elevation head. When considering dynamic systems, there is a third term needed, the venturi meter in the diagram on the left shows two columns of a measurement fluid at different heights. The height of column of fluid is proportional to the pressure of the fluid. To demonstrate a classical measurement of pressure head, we could replace the working fluid with another fluid having different physical properties. For example, if the fluid was water and we replaced it with mercury at the same pressure. In fact the specific weight of water is 9.8 kN/m3, so, for any particular measurement of pressure head, the height of a column of water will be about 13.6 times taller than a column of mercury would be. So if a water column meter reads 13.6 cm H2O and this example demonstrates why there is some confusion surrounding pressure head and its relationship to pressure. Scientists frequently use columns of water to measure pressure, since for a given fluid, ψ We would normally use pressure head calculations in areas in which g is constant. However, if the field fluctuates, we can prove that pressure head fluctuates with it. If we consider what would happen if gravity decreases, we would expect the fluid in the venturi meter shown above to withdraw from the pipe up into the vertical columns, in the case of weightlessness, the pressure head approaches infinity. Fluid in the pipe may leak out of the top of the vertical columns, to simulate negative gravity, we could turn the venturi meter shown above upside down. In this case gravity is negative, and we would expect the fluid in the pipe to pour out the vertical columns. If p <0 and g >0, we observe that the head is also negative. This is called a siphon, and is caused by a vacuum inside the vertical columns. In many venturis, the column on the left has fluid in it, if p <0 and g <0, we observe that the pressure head is again positive, predicting that the venturi meter shown above would look the same, only upside down. In this situation, gravity causes the fluid to plug the siphon holes. The above situations imply that the Bernoulli equation, from which we obtain static pressure head, is extremely versatile, a mercury barometer is one of the classic uses of static pressure head
Pressure head
–
A
Venturi meter with two pressure instruments open to the ambient air. (and) If the meter is turned upside down, we say by convention that and the fluid inside the vertical columns will pour out the two holes. See discussion below.
30.
Astronomical clock
–
The term is loosely used to refer to any clock that shows, in addition to the time of day, astronomical information. The term should not be confused with astronomical regulator, a high precision, Astronomical clocks usually represent the solar system using the geocentric model. The center of the dial is marked with a disc or sphere representing the earth. The sun is represented by a golden sphere, shown rotating around the earth once a day around a 24-hour analog dial. This view accords both with daily experience and with the world view of pre-Copernican Europe. Research in 2011 and 2012 led a group of researchers to posit that European astronomical clocks are descended from the technology of the Antikythera mechanism. In the 11th century, the Song Dynasty Chinese horologist, mechanical engineer, Su Song is noted for having incorporated an escapement mechanism and earliest known endless power-transmitting chain drive for his clock-tower and armillary sphere to function. They no longer exist, but detailed descriptions of their design and construction survive, wallingfords clock may have shown the sun, moon, stars and planets, and had, in addition, a wheel of fortune and an indicator of the state of the tide at London Bridge. De Dondis clock was a construction with 107 moving parts, showing the positions of the sun, moon. Both these clocks, and others like them, were less accurate than their designers would have wished. The gear ratios may have been calculated, but their manufacture was somewhat beyond the mechanical abilities of the time. Astronomical clocks were built as demonstration or exhibition pieces, to impress as much as to educate or inform, the challenge of building these masterpieces meant that clockmakers would continue to produce them, to demonstrate their technical skill and their patrons wealth. The philosophical message of an ordered, heavenly-ordained universe, which accorded with the Gothic era view of the world, the Science Museum has a scale model of the Cosmic Engine, which Su Sung, a Chinese polymath, designed and constructed in China in 1092. A full-sized working replica of Su Sungs clock exists in the Republic of China s National Museum of Natural Science and this full-scale, fully functional replica, approximately 12 meters in height, was constructed from Su Sungs original descriptions and mechanical drawings. The most sophisticated water-powered astronomical clock was Al-Jazaris castle clock, considered to be an example of a programmable analog computer. It was a device that was about 33 meters high. The Strasbourg Cathedral has housed three different astronomical clocks since the 14th century, the first clock was built between 1352 and 1354 and stopped working sometime at the beginning of the 16th century. A second clock was built by Herlin, Conrad Dasypodius, the Habrecht brothers
Astronomical clock
–
Face of the
Astronomical Clock, in
Old Town Square,
Prague.
Astronomical clock
–
Richard of Wallingford is shown measuring with a pair of compasses in this 14th-century miniature.
Astronomical clock
–
Strasbourg astronomical clock
Astronomical clock
–
Prague Astronomical Clock
.[unreliable source?]
"Clepsydra". Encyclopedia Americana. 1920.
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