1.
Clock
–
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
2.
Watch
–
A watch is a small timepiece intended to be carried or worn by a person. It is designed to keep working despite the motions caused by the persons activities, a wristwatch is designed to be worn around the wrist, attached by a watch strap or other type of bracelet. A pocket watch is designed for a person to carry in a pocket, watches evolved in the 17th century from spring-powered clocks, which appeared as early as the 14th century. During most of its history the watch was a device, driven by clockwork, powered by winding a mainspring. In the 1960s the electronic quartz watch was invented, which was powered by a battery, by the 1980s the quartz watch had taken over most of the market from the mechanical watch. Today most inexpensive and medium-priced watches, used mainly for timekeeping, have quartz movements, various extra features, called complications, such as moon-phase displays and the different types of tourbillon, are sometimes included. Modern watches often display the day, date, month and year, time-related features such as timers, chronographs and alarm functions are common. Some modern designs incorporate calculators, GPS and Bluetooth technology or have heart-rate monitoring capabilities, some watches use radio clock technology to regularly correct the time. Developments in the 2010s include smartwatches, which are elaborate computer-like electronic devices designed to be worn on a wrist and they generally incorporate timekeeping functions, but these are only small fractions of what the smartwatch can do. The study of timekeeping is known as horology, watches evolved from portable spring-driven clocks, which first appeared in 15th century Europe. Watches werent widely worn in pockets until the 17th century, one account says that the word watch came from the Old English word woecce which meant watchman, because it was used by town watchmen to keep track of their shifts at work. Another says that the term came from 17th century sailors, who used the new mechanisms to time the length of their shipboard watches, the increased accuracy of the balance wheel focused attention on errors caused by other parts of the movement, igniting a two-century wave of watchmaking innovation. The first thing to be improved was the escapement, the verge escapement was replaced in quality watches by the cylinder escapement, invented by Thomas Tompion in 1695 and further developed by George Graham in the 1720s. The British had predominated in watch manufacture for much of the 17th and 18th centuries, aaron Lufkin Dennison started a factory in 1851 in Massachusetts that used interchangeable parts, and by 1861 it was running a successful enterprise incorporated as the Waltham Watch Company. The concept of the wristwatch goes back to the production of the very earliest watches in the 16th century, elizabeth I of England received a wristwatch from Robert Dudley in 1571, described as an arm watch. The oldest surviving wristwatch is one made in 1806 and given to Joséphine de Beauharnais, from the beginning, wrist watches were almost exclusively worn by women, while men used pocket-watches up until the early 20th century. The Garstin Company of London patented a Watch Wristlet design in 1893, officers in the British Army began using wristwatches during colonial military campaigns in the 1880s, such as during the Anglo-Burma War of 1885. In continental Europe Girard-Perregaux and other Swiss watch makers began supplying German naval officers with wrist watches in about 1880 and these early models were essentially standard pocket-watches fitted to a leather strap but, by the early 20th century, manufacturers began producing purpose-built wristwatches
3.
Hour
–
An hour is a unit of time conventionally reckoned as 1⁄24 of a day and scientifically reckoned as 3, 599–3,601 seconds, depending on conditions. The seasonal, temporal, or unequal hour was established in the ancient Near East as 1⁄12 of the night or daytime, such hours varied by season, latitude, and weather. It was subsequently divided into 60 minutes, each of 60 seconds, the modern English word hour is a development of the Anglo-Norman houre and Middle English ure, first attested in the 13th century. It displaced the Old English tide and stound, the Anglo-Norman term was a borrowing of Old French ure, a variant of ore, which derived from Latin hōra and Greek hṓrā. Like Old English tīd and stund, hṓrā was originally a word for any span of time, including seasons. Its Proto-Indo-European root has been reconstructed as *yeh₁-, making hour distantly cognate with year, the time of day is typically expressed in English in terms of hours. Whole hours on a 12-hour clock are expressed using the contracted phrase oclock, Hours on a 24-hour clock are expressed as hundred or hundred hours. Fifteen and thirty minutes past the hour is expressed as a quarter past or after and half past, respectively, fifteen minutes before the hour may be expressed as a quarter to, of, till, or before the hour. Sumerian and Babylonian hours divided the day and night into 24 equal hours, the ancient Egyptians began dividing the night into wnwt at some time before the compilation of the Dynasty V Pyramid Texts in the 24th century BC. By 2150 BC, diagrams of stars inside Egyptian coffin lids—variously known as diagonal calendars or star clocks—attest that there were exactly 12 of these. The coffin diagrams show that the Egyptians took note of the risings of 36 stars or constellations. Each night, the rising of eleven of these decans were noted, the original decans used by the Egyptians would have fallen noticeably out of their proper places over a span of several centuries. By the time of Amenhotep III, the priests at Karnak were using water clocks to determine the hours and these were filled to the brim at sunset and the hour determined by comparing the water level against one of its twelve gauges, one for each month of the year. During the New Kingdom, another system of decans was used, the later division of the day into 12 hours was accomplished by sundials marked with ten equal divisions. The morning and evening periods when the failed to note time were observed as the first and last hours. The Egyptian hours were closely connected both with the priesthood of the gods and with their divine services, by the New Kingdom, each hour was conceived as a specific region of the sky or underworld through which Ras solar bark travelled. Protective deities were assigned to each and were used as the names of the hours, as the protectors and resurrectors of the sun, the goddesses of the night hours were considered to hold power over all lifespans and thus became part of Egyptian funerary rituals. The Egyptian for astronomer, used as a synonym for priest, was wnwty, the earliest forms of wnwt include one or three stars, with the later solar hours including the determinative hieroglyph for sun
4.
Minute
–
The minute is a unit of time or of angle. As a unit of time, the minute is equal to 1⁄60 of an hour, in the UTC time standard, a minute on rare occasions has 61 seconds, a consequence of leap seconds. As a unit of angle, the minute of arc is equal to 1⁄60 of a degree, although not an SI unit for either time or angle, the minute is accepted for use with SI units for both. The SI symbols for minute or minutes are min for time measurement, the prime is also sometimes used informally to denote minutes of time. In contrast to the hour, the minute does not have a historical background. What is traceable only is that it started being recorded in the Middle Ages due to the ability of construction of precision timepieces, however, no consistent records of the origin for the division as 1⁄60 part of the hour have ever been found, despite many speculations. Historically, the word comes from the Latin pars minuta prima. This division of the hour can be refined with a second small part. For even further refinement, the third remains in some languages, for example Polish and Turkish. The symbol notation of the prime for minutes and double prime for seconds can be seen as indicating the first, international System of Units Latitude and longitude Orders of magnitude Henry Campbell Black, Blacks Law Dictionary, 6th Edition, entry on Minute. West Publishing Company, St. Paul, Minnesota,1991
5.
Turn (geometry)
–
A turn is a unit of plane angle measurement equal to 2π radians, 360° or 400 gon. A turn is also referred to as a revolution or complete rotation or full circle or cycle or rev or rot, a turn can be subdivided in many different ways, into half turns, quarter turns, centiturns, milliturns, binary angles, points etc. A turn can be divided in 100 centiturns or 1000 milliturns, with each corresponding to an angle of 0. 36°. A protractor divided in centiturns is normally called a percentage protractor, binary fractions of a turn are also used. Sailors have traditionally divided a turn into 32 compass points, the binary degree, also known as the binary radian, is 1⁄256 turn. The binary degree is used in computing so that an angle can be represented to the maximum possible precision in a single byte, other measures of angle used in computing may be based on dividing one whole turn into 2n equal parts for other values of n. The notion of turn is used for planar rotations. Two special rotations have acquired appellations of their own, a rotation through 180° is commonly referred to as a half-turn, the word turn originates via Latin and French from the Greek word τόρνος. In 1697, David Gregory used π/ρ to denote the perimeter of a divided by its radius. However, earlier in 1647, William Oughtred had used δ/π for the ratio of the diameter to perimeter, the first use of the symbol π on its own with its present meaning was in 1706 by the Welsh mathematician William Jones. Euler adopted the symbol with that meaning in 1737, leading to its widespread use, percentage protractors have existed since 1922, but the terms centiturns and milliturns were introduced much later by Sir Fred Hoyle. The German standard DIN1315 proposed the unit symbol pla for turns, since 2011, the HP 39gII and HP Prime support the unit symbol tr for turns. In 2016, support for turns was also added to newRPL for the HP 50g, one turn is equal to 2π radians. In 1958, Albert Eagle proposed the Greek letter tau τ as a symbol for 1/2π and his proposal used a pi with three legs symbol to denote the constant. In 2010, Michael Hartl proposed to use tau to represent Palais circle constant, τ=2π. First, τ is the number of radians in one turn, which allows fractions of a turn to be expressed directly, for instance. Second, τ visually resembles π, whose association with the constant is unavoidable. Hartls Tau Manifesto gives many examples of formulas that are simpler if tau is used instead of pi, however, a rebuttal was given in The Pi Manifesto, stating a variety of reasons tau should not supplant pi
6.
Second
–
The second is the base unit of time in the International System of Units. It is qualitatively defined as the division of the hour by sixty. SI definition of second is the duration of 9192631770 periods of the corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom. Seconds may be measured using a mechanical, electrical or an atomic clock, SI prefixes are combined with the word second to denote subdivisions of the second, e. g. the millisecond, the microsecond, and the nanosecond. Though SI prefixes may also be used to form multiples of the such as kilosecond. The second is also the unit of time in other systems of measurement, the centimetre–gram–second, metre–kilogram–second, metre–tonne–second. Absolute zero implies no movement, and therefore zero external radiation effects, the second thus defined is consistent with the ephemeris second, which was based on astronomical measurements. The realization of the second is described briefly in a special publication from the National Institute of Standards and Technology. 1 international second is equal to, 1⁄60 minute 1⁄3,600 hour 1⁄86,400 day 1⁄31,557,600 Julian year 1⁄, more generally, = 1⁄, the Hellenistic astronomers Hipparchus and Ptolemy subdivided the day into sixty parts. They also used an hour, simple fractions of an hour. No sexagesimal unit of the day was used as an independent unit of time. The modern second is subdivided using decimals - although the third remains in some languages. The earliest clocks to display seconds appeared during the last half of the 16th century, the second became accurately measurable with the development of mechanical clocks keeping mean time, as opposed to the apparent time displayed by sundials. The earliest spring-driven timepiece with a hand which marked seconds is an unsigned clock depicting Orpheus in the Fremersdorf collection. During the 3rd quarter of the 16th century, Taqi al-Din built a clock with marks every 1/5 minute, in 1579, Jost Bürgi built a clock for William of Hesse that marked seconds. In 1581, Tycho Brahe redesigned clocks that displayed minutes at his observatory so they also displayed seconds, however, they were not yet accurate enough for seconds. In 1587, Tycho complained that his four clocks disagreed by plus or minus four seconds, in 1670, London clockmaker William Clement added this seconds pendulum to the original pendulum clock of Christiaan Huygens. From 1670 to 1680, Clement made many improvements to his clock and this clock used an anchor escapement mechanism with a seconds pendulum to display seconds in a small subdial
7.
Digital clock
–
A digital clock is a type of clock that displays the time digitally, as opposed to an analog clock, where the time is indicated by the positions of rotating hands. Digital clocks are often associated with electronic drives, but the description refers only to the display. The biggest digital clock is the Lichtzelt Pegel on the television tower Rheinturm Düsseldorf, the first digital pocket watch was the invention of Austrian engineer Josef Pallweber who created his jump-hour mechanism in 1883. Instead of a dial, the jump-hour featured two windows in an enamel dial, through which the hours and minutes are visible on rotating discs. By 1885 Pallweber mechanism was already on the market in pocket watches by Cortébert and IWC, arguably contributing to the subsequent rise, the principles of Pallweber jump-hour movement had appeared in wristwatches by the 1920s and are still used today. While the original inventor didnt have a brand at the time. Plato clocks used an idea but a different layout. These spring-wound pieces consisted of a cylinder with a column inside, affixed to which were small digital cards with numbers printed on them. The Plato clocks were introduced at the St. Louis World Fair in 1904, eugene Fitch of New York patented the clock design in 1903. 13 years earlier Josef Pallweber had patented the same invention using digital cards in Germany, the German factory Aktiengesellschaft für Uhrenfabrikation Lenzkirch made such digital clocks in 1893 and 1894. The earliest patent for an alarm clock was registered by D. E Protzmann and others on October 23,1956. Protzmann and his associates also patented another digital clock in 1970, two side-plates held digital numerals between them, while an electric motor and cam gear outside controlled movement. In 1970, the first digital wristwatch with an LED display was mass-produced, called the Pulsar, and produced by the Hamilton Watch Company, this watch was hinted at two years prior when the same company created a prototype digital watch for Kubricks 2001, A Space Odyssey. Throughout the 1970s, despite the initial hefty cost of digital watches, over the years, many different types of digital alarm clocks have been developed. In Soviet Russia, the 7-segment digital clocks were known as Elektronika 7, Digital clocks typically use the 50 or 60 hertz oscillation of AC power or a 32,768 hertz crystal oscillator as in a quartz clock to keep time. Most digital clocks display the hour of the day in 24-hour format, in the United States and a few other countries, emulations of analog-style faces often use an LCD screen, and these are also sometimes described as digital. To represent the time, most digital clocks use a seven-segment LED, VFD and they generally also include other elements to indicate whether the time is AM or PM, whether or not an alarm is set, and so on. Digital clocks that run on electricity and have no battery must be reset every time the power is cut off or if they are moved
8.
24-hour analog dial
–
Clocks and watches with a 24-hour analog dial have an hour hand that makes one complete revolution, 360°, in a day. The more familiar 12-hour analog dial has a hand that makes two complete revolutions in a day. Twenty-four-hour analog clocks and watches are used today by pilots, scientists, and the military, note that this definition refers to the use of a complete circular dial to represent a 24-hour day. Using the numbers from 0 to 23 to mark the day is the 24-hour clock system, sundials use 24-hour analog dials—the shadow traces a path that repeats approximately once per day. Many sundials are marked with the double-XII or double-12 system, in which the numbers I to XII are used twice, once for the morning hours, so VI appears twice on many dials, once near sunrise and once near sunset. Modern 24-hour analog dials—other than sundials—are almost always marked with 24 numbers or hour marks around the edge and these dials do not need to indicate AM or PM. The ancient Egyptians divided the day into 24 hours, there are diagrams of circles divided into 24 sections in the astronomical ceiling in the tomb of Senemut. Sundials use some or all of the 24-hour dial, because they show the position of the sun in the sky, sometimes, for aesthetic rather than practical reasons, all the 24 hour marks are shown. Medieval clocks often used the 24-hour analog dial, influenced by the example of the astrolabe. In Italy, the numbers from 1 to 24 were used, on Italian clocks, though, the I was often shown at the right side of the dial, rather than the top. This probably reflects the influence of the Italian timekeeping system, which started counting the hours of the day at sunset or twilight. In northern Europe, the double XII system was superseded during the 14th and 15th centuries by the single XII. The 24-hour analog dial continued to be used, but primarily by technicians, astronomers, scientists, john Harrison, Thomas Tompion, and Mudge built a number of clocks with 24-hour analog dials, particularly when building astronomical and nautical instruments. In the 20th century, the 24-hour analog dial was adopted by radio amateurs, pilots, submariners, 24-hour analog watches and clocks are still being manufactured today, and are sought after by collectors and enthusiasts. A famous brand is the Glycine Airman watch, other manufacturers who make 24-hour analog watches include Breitling, Raketa, Vostok, Fortis, Poljot, Swatch, and many others. The major variation in the design of 24-hour analog dials is the location of midnight, although always opposite each other, 180° apart, noon is sometimes at the top, sometimes at the bottom. A few rare variants place noon and midnight at the right, there is no ambiguity if the 24-hour numbering is used. In the United States, the government and military commonly use 24-hour clocks having noon at the bottom, the Chinese traditional shi-ke system may be an optimum design of 24-hour clock
9.
Military
–
The armed forces of a country are its government-sponsored defense, fighting forces, and organizations. They exist to further the foreign and domestic policies of their body and to defend that body. Armed force is the use of armed forces to achieve political objectives, the study of the use of armed forces is called military science. Broadly speaking, this involves considering offense and defense at three levels, strategy, operational art, and tactics, all three levels study the application of the use of force in order to achieve a desired objective. In most countries the basis of the forces is the military. However, armed forces can include other paramilitary structures, the obvious benefit to a country in maintaining armed forces is in providing protection from foreign threats and from internal conflict. In recent decades armed forces personnel have also used as emergency civil support roles in post-disaster situations. On the other hand, they may harm a society by engaging in counter-productive warfare. Expenditure on science and technology to develop weapons and systems sometimes produces side benefits, although some claim that greater benefits could come from targeting the money directly
10.
24-hour clock
–
The 24-hour clock is the convention of time keeping in which the day runs from midnight to midnight and is divided into 24 hours, indicated by the hours passed since midnight, from 0 to 23. This system is the most commonly used time notation in the world today, in the practice of medicine, the 24-hour clock is generally used in documentation of care as it prevents any ambiguity as to when events occurred in a patients medical history. It is popularly referred to as time in the United States. In the case of a second, the value of ss may extend to 60. A leading zero is added for numbers under 10 and this zero is optional for the hours, but very commonly used in computer applications, where many specifications require it. Where subsecond resolution is required, the seconds can be a fraction, that is. The most commonly used separator symbol between hours, minutes and seconds is the colon, which is also the used in ISO8601. In the past, some European countries used the dot on the line as a separator, in some contexts, no separator is used and times are written as, for example,2359. In East Asia, time notation was 24-hour before westernization in modern times, the clocks were changed into 12 dual-hours style when they were shipped to China in the Qing dynasty. In the 24-hour time notation, the day begins at midnight,00,00, and the last minute of the day begins at 23,59. Where convenient, the notation 24,00 may also be used to refer to midnight at the end of a given date – that is,24,00 of one day is the time as 00,00 of the following day. The notation 24,00 mainly serves to refer to the end of a day in a time interval. A typical usage is giving opening hours ending at midnight, similarly, some railway timetables show 00,00 as departure time and 24,00 as arrival time. Legal contracts often run from the date at 00,00 until the end date at 24,00. While the 24-hour notation unambiguously distinguishes between midnight at the start and end of any date, there is no commonly accepted distinction among users of the 12-hour notation. Sometimes the use of 00,00 is also avoided, in variance with this, the correspondence manual for the U. S. Navy and U. S. Marine Corps formerly specified 0001 to 2400. The manual was updated in June 2015 to use 0000 to 2359, time-of-day notations beyond 24,00 are not commonly used and not covered by the relevant standards. In most countries, computers by default show the time in 24-hour notation, for example, Microsoft Windows and macOS activate the 12-hour notation by default only if a computer is in a handful of specific language and region settings
11.
Timer
–
A timer is a specialized type of clock for measuring time intervals. By function timers can be categorized to two main types, a simple example for this type is an hourglass. By working method timers have two groups, Hardware and Software timers. Some timers sound an audible indication that the interval has expired. Time switches, timing mechanisms which activate a switch, are also called timers. Mechanical timers use clockwork to measure time, manual timers are typically set by turning a dial to the time interval desired, turning the dial stores energy in a mainspring to run the mechanism. They function similarly to an alarm clock, the energy in the mainspring causes a balance wheel to rotate back. Each swing of the releases the gear train to move forward by a small fixed amount, causing the dial to move steadily backward until it reaches zero. The mechanical kitchen timer was invented in 1926 by Thomas Norman Hicks, some less accurate, cheaper mechanisms use a flat paddle called a fan fly that spins against air resistance, low-precision mechanical egg-timers are sometimes of this type. The simplest and oldest type of mechanical timer is the hourglass, the most common use of this type is in the flasher units that flash turn signals in automobiles, and sometimes in Christmas lights. This is a type of multivibrator. An electromechanical cam timer uses a small synchronous AC motor turning a cam against a comb of switch contacts, the AC motor is turned at an accurate rate by the alternating current, which power companies carefully regulate. Gears drive a shaft at the rate, and turn the cam. The most common application of this now is in washers, driers and dishwashers. This type of timer often has a clutch between the gear train and the cam, so that the cam can be turned to reset the time. In the past, these timers were often combined with electrical relays to create electro-mechanical controllers. Electromechanical timers reached a state of development in the 1950s and 1960s because of their extensive use in aerospace. Programmable electromechanical timers controlled launch sequence events in early rockets and ballistic missiles, as digital electronics has progressed and dropped in price, electronic timers have become more advantageous
12.
Roman numerals
–
The numeric system represented by Roman numerals originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Numbers in this system are represented by combinations of letters from the Latin alphabet, Roman numerals, as used today, are based on seven symbols, The use of Roman numerals continued long after the decline of the Roman Empire. The numbers 1 to 10 are usually expressed in Roman numerals as follows, I, II, III, IV, V, VI, VII, VIII, IX, Numbers are formed by combining symbols and adding the values, so II is two and XIII is thirteen. Symbols are placed left to right in order of value. Named after the year of its release,2014 as MMXIV, the year of the games of the XXII Olympic Winter Games The standard forms described above reflect typical modern usage rather than a universally accepted convention. Usage in ancient Rome varied greatly and remained inconsistent in medieval, Roman inscriptions, especially in official contexts, seem to show a preference for additive forms such as IIII and VIIII instead of subtractive forms such as IV and IX. Both methods appear in documents from the Roman era, even within the same document, double subtractives also occur, such as XIIX or even IIXX instead of XVIII. Sometimes V and L are not used, with such as IIIIII. Such variation and inconsistency continued through the period and into modern times. Clock faces that use Roman numerals normally show IIII for four o’clock but IX for nine o’clock, however, this is far from universal, for example, the clock on the Palace of Westminster in London uses IV. Similarly, at the beginning of the 20th century, different representations of 900 appeared in several inscribed dates. For instance,1910 is shown on Admiralty Arch, London, as MDCCCCX rather than MCMX, although Roman numerals came to be written with letters of the Roman alphabet, they were originally independent symbols. The Etruscans, for example, used
13.
Longcase clock
–
A longcase clock, also tall-case clock, floor clock, or grandfather clock, is a tall, freestanding, weight-driven pendulum clock with the pendulum held inside the tower or waist of the case. Clocks of this style are commonly 1. 8–2.4 metres tall, the case often features elaborately carved ornamentation on the hood, which surrounds and frames the dial, or clock face. The English clockmaker William Clement is credited with the development of this form in 1670, today they are kept mainly for their decorative and antique value. The advent of the clock is due to the invention of the anchor escapement mechanism by Robert Hooke around 1658. Prior to that, pendulum clock used an older verge escapement mechanism. Long pendulums with such wide swings could not be fitted within a case, the anchor mechanism reduced the pendulums swing to around 4° to 6°, allowing clockmakers to use longer pendulums, which had slower beats. These consumed less power allowing clocks to run longer between windings, caused friction and wear in the movement, and were more accurate. Almost all longcase clocks use a seconds pendulum meaning that each swing takes one second and these are about a metre long, requiring a long narrow case. The long narrow case actually predated the anchor clock by a few decades, however, once the seconds pendulum began to be used, this long weight case proved perfect to house it as well. British clockmaker William Clement, who disputed credit for the escapement with Robert Hooke. Within the year Thomas Tompion, the most prominent British clockmaker, was making them too, modern longcase clocks use a more accurate variation of the anchor escapement called the deadbeat escapement. Traditionally, longcase clocks were made two types of movement, eight-day and one-day movements. A clock with a movement required winding only once a week. Eight-day clocks are driven by two weights – one driving the pendulum and the other the striking mechanism, which usually consisted of a bell or chimes. Such movements usually have two keyholes, one on side of the dial to wind each one. By contrast, 30-hour clocks often had a weight to drive both the timekeeping and striking mechanisms. Some 30-hour clocks were made with false keyholes, for customers who wished that guests to their home would think that the household was able to afford the more expensive eight-day clock, all modern striking longcase clocks have eight-day movements. Most longcase clocks are cable-driven, meaning that the weights are suspended by cables, if the cable were attached directly to the weight, the load would cause rotation and untwist the cable strands, so the cable wraps around a pulley mounted to the top of each weight
14.
Wireless telegraphy
–
Wireless telegraphy is the transmission of electric telegraphy signals without wires. Wireless telegraphy came to mean Morse code transmitted by radio waves, initially called Hertzian waves, the primitive spark radio transmitters used until World War 1 could not transmit audio. The code sounded like musical beeps in the earphone of the receiver, the receiving radio operator would translate the beeps back into text. The first practical wireless telegraphy transmitters and receivers were developed by Guglielmo Marconi beginning in 1895, by 1910 communication by Hertzian waves was universally referred to as radio, and the term wireless telegraphy has been largely replaced by the more modern term radiotelegraphy. The transmission of sound began to displace wireless telegraphy by the 1920s for many applications, continuous wave radiotelegraphy is regulated by the International Telecommunication Union as emission type A1A. Today, due to modern text transmission methods, Morse code radiotelegraphy for commercial use has become obsolete. On shipboard the computer and satellite linked GMDSS system has largely replaced Morse as a means of communication, Telegraphy is taught on a very limited basis by the military. A CW coastal station, KSM, still exists in California, run primarily as a museum by volunteers, Radio beacons, particularly in the aviation service, but also as placeholders for commercial ship-to-shore systems, also transmit Morse but at very slow speeds. The US Federal Communications Commission does still issue a lifetime commercial Radiotelegraph Operator License and this requires passing a simple written test on regulations, a more complex written exam on technology, and demonstrating Morse reception at 20 words per minute plain language and 16 wpm code groups. Wireless telegraphy is still used today by amateur radio hobbyists where it is commonly referred to as radio telegraphy, continuous wave. However its knowledge is not required to obtain any class of amateur license, a number of wireless electrical signaling schemes including electric currents through water and the ground were investigated for telegraphy before practical radio systems became available. The original telegraph used two wires between two stations to form an electrical circuit or loop. This led to speculation that it might be possible to both wires and therefore transmit telegraph signals through the ground without any wires connecting the stations. Other attempts were made to send the current through bodies of water, in order to span rivers. The first wireless voice telecommunication device, invented in 1880, was the photophone, both electrostatic and electromagnetic induction were used to develop wireless telegraph systems that saw limited commercial application. This system was successful technically but not economically, as there turned out to be little interest by train travelers in a telegraph service. During the Great Blizzard of 1888, this system was used to send, the disabled trains were able to maintain communications via their Edison induction wireless telegraph systems, perhaps the first successful use of wireless telegraphy to send distress calls. The most successful creator of an electromagnetic induction telegraph system was William Preece in the United Kingdom, beginning with tests across the Bristol Channel in 1892, Preece was able to telegraph across gaps of about 5 kilometres
15.
Clockwise
–
Rotation can occur in two possible directions. A clockwise motion is one that proceeds in the direction as a clocks hands, from the top to the right, then down and then to the left. The opposite sense of rotation or revolution is counterclockwise or anticlockwise, in a mathematical sense, a circle defined parametrically in a positive Cartesian plane by the equations x = cos t and y = sin t is traced counterclockwise as t increases in value. Before clocks were commonplace, the terms sunwise and deasil, deiseil and even deocil from the Scottish Gaelic language, widdershins or withershins was used for counterclockwise. The terms clockwise and counterclockwise can only be applied to a rotational motion once a side of the plane is specified. For example, the rotation of the Earth is clockwise when viewed from above the South Pole. Clocks traditionally follow this sense of rotation because of the clocks predecessor, clocks with hands were first built in the Northern Hemisphere, and they were made to work like sundials. In order for a sundial to work, it must be placed looking northward. Then, when the Sun moves in the sky, the shadow cast on the side of the sundial moves with the same sense of rotation. This is why hours were drawn in sundials in that manner, note, however, that on a vertical sundial, the shadow moves in the opposite direction, and some clocks were constructed to mimic this. The best-known surviving example is the clock in the Münster Cathedral. Occasionally, clocks whose hands revolve counterclockwise are nowadays sold as a novelty, historically, some Jewish clocks were built that way, for example in some synagogue towers in Europe, to accord with right-to-left reading in the Hebrew language. In 2014 under Bolivian president Evo Morales, the clock outside the Legislative Assembly in Plaza Murillo, typical nuts, screws, bolts, bottle caps, and jar lids are tightened clockwise and loosened counterclockwise in accordance with the right-hand rule. Almost all threaded objects obey this rule except for a few left-handed exceptions described below, sometimes the opposite sense of threading is used for a special reason. A thread might need to be left-handed to prevent operational stresses from loosening it, for bicycle pedals, the one on the left must be reverse-threaded to prevent it unscrewing during use. Similarly, the whorl of a spinning wheel uses a left-hand thread to keep it from loosening. A turnbuckle has right-handed threads on one end and left-handed threads on the other, in trigonometry and mathematics in general, plane angles are conventionally measured counterclockwise, starting with 0° or 0 radians pointing directly to the right, and 90° pointing straight up. However, in navigation, compass headings increase clockwise around the face, starting with 0° at the top of the compass
16.
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
17.
Canonical hours
–
In the practice of Christianity, canonical hours mark the divisions of the day in terms of periods of fixed prayer at regular intervals. A Book of Hours normally contains a version of, or selection from, such prayers. The practice of daily prayers grew from the Jewish practice of reciting prayers at set times of the day, for example, in the Book of Acts, Peter, Psalm 119,164 states, Seven times a day I praise you for your righteous laws. This practice is believed to have passed down through the centuries from the Apostles. As monasticism spread, the practice of specified hours and liturgical formats began to develop, in 525, Benedict of Nursia set out one of the earliest schemes for the recitation of the Psalter at the Office. With the Cluniac reforms of the 11th century there was a new emphasis on liturgy, the current official version of the hours in the Roman rite of the Roman Catholic Church is called the liturgy of the hours in North America or divine office in Ireland and Britain. In the Anglican tradition, they are known as the daily office, to distinguish them from the other offices of the Church, i. e. holy communion, baptism. In the Orthodox Church, the canonical hours may be referred to as the services. The usage among the Oriental Orthodox Churches and the Assyrian Church of the East and of their Eastern Catholic counterparts all differ from each other, building on the recitation of psalms and canticles from scripture, the Church has added hymns, hagiographical readings, and other prayers. As is noted above, the canonical hours stemmed from Jewish prayer, in the Old Testament, God commanded the Israelite priests to offer sacrifices of animals in the morning and evening. Eventually, these sacrifices moved from the Tabernacle to the Temple built by Solomon in Jerusalem, during the Babylonian Exile, when the Temple was no longer in use, the first synagogues were established, and the services of Torah readings, psalms, and hymns began to evolve. This sacrifice of praise began to be substituted for the sacrifices of animals, after the people returned to Judea, the prayer services were incorporated into Temple worship as well. As time passed, the Jews began to be scattered across the Greco-Roman world in what is known as the Diaspora, by the time of the Roman Empire, the Jews began to follow the Roman system of conducting the business day in scheduling their times for prayer. The narrative of Jesus crucifixion and death refers to the sixth and ninth hours, Now when the hour had come. And at the ninth hour Jesus cried out with a loud voice …, the first miracle of the apostles, the healing of the crippled man on the temple steps, occurred because Peter and John went to the Temple to pray. Also, one of the moments of the early Church. As Christianity began to separate from Judaism, the practice of praying at fixed times continued, the early church was known to pray the Psalms, which have remained the principal part of the canonical hours. The prayers could be prayed individually or in groups, by the fourth century, the elements of the canonical hours were more or less established
18.
Clock tower
–
Clock towers are a specific type of building which houses a turret clock and has one or more clock faces on the upper exterior walls. Many clock towers are freestanding structures but they can also adjoin or be located on top of another building, Clock towers are a common sight in many parts of the world with some being iconic buildings. One example is the Elizabeth Tower in London, there are many structures which may have clocks or clock faces attached to them and some structures have had clocks added to an existing structure. According to the Council on Tall Buildings and Urban Habitat a building is defined as a building if at least fifty percent of its height is made up of plates containing habitable floor area. Structures that do not meet this criterion, are defined as towers, not all clocks on buildings therefore make the building into a clock tower. The mechanism inside the tower is known as a turret clock and it often marks the hour by sounding large bells or chimes, sometimes playing simple musical phrases or tunes. Although clock towers are today mostly admired for their aesthetics, they served an important purpose. Before the middle of the century, most people did not have watches. The first clocks didnt have faces, but were solely striking clocks and they were therefore placed in towers so the bells would be audible for a long distance. Clock towers were placed near the centres of towns and were often the tallest structures there, as clock towers became more common, the designers realized that a dial on the outside of the tower would allow the townspeople to read the time whenever they wanted. The use of clock towers dates back to the antiquity, the earliest clock tower was the Tower of the Winds in Athens which featured eight sundials. In its interior, there was also a clock, driven by water coming down from the Acropolis. In Song China, a clock tower was designed by Su Song and erected at Kaifeng in 1088. In England, a clock was put up in a tower, the medieval precursor to Big Ben, at Westminster, in 1288. Al-Jazari constructed a clock and described it in his Book of Knowledge of Ingenious Mechanical Devices in 1206. It was about 3.3 metres high, and had multiple functions alongside timekeeping, line synchronous tower clocks were introduced in the United States in the 1920s. Some clock towers have become famous landmarks, the Allen-Bradley Clock Tower in Milwaukee, Wisconsin has the largest four faced clock in the world, with clock diameter 40 ft 3 1⁄2 in, it is 283 ft tall. The Elizabeth Tower has the largest chiming clock in the world, the tallest freestanding clock tower in the world is the Joseph Chamberlain Memorial Clock Tower at the University of Birmingham in Birmingham, United Kingdom
19.
Bell tower
–
A bell tower is a tower that contains one or more bells, or that is designed to hold bells even if it has none. Church bell towers often incorporate clocks, and secular towers usually do, the Italian term campanile, deriving from the word campana meaning bell, is synonymous with bell tower, though in English usage Campanile tends to be used to refer to a free standing bell tower. A bell tower may also in some traditions be called a belfry, though this term may refer specifically to the substructure that houses the bells. The tallest free-standing bell tower in the world, approximately 110 m high, is the Joseph Chamberlain Memorial Clock Tower, located at the University of Birmingham, bells are rung from a tower to enable them to be heard at a distance. Church bells can signify the time for worshippers to go to church for a communal service and they are also rung on special occasions such as a wedding, or a funeral service. In some religious traditions they are used within the liturgy of the service to signify to people that a particular part of the service has been reached. A bell tower may have a bell, or a collection of bells which are tuned to a common scale. They may be stationary and chimed, rung randomly by swinging through a small arc and they may house a carillon or chimes, in which the bells are sounded by hammers connected via cables to a keyboard. These can be found in churches and secular buildings in Europe and America including college. A variety of electronic devices exist to simulate the sound of bells, some churches have an exconjuratory in the bell tower, a space where ceremonies were conducted to ward off weather-related calamities, like storms and excessive rain. The main bell tower of the Cathedral of Murcia has four, in addition, most Christian denominations ring church bells to call the faithful to worship, signalling the start of a mass or service of worship. The Christian tradition of the ringing of bells from a belltower is analogous to Islamic tradition of the adhan from a minaret. In AD400, Paulinus of Nola introduced church bells into the Christian Church, by the 11th century, bells housed in belltowers became commonplace. Historic bell towers exist throughout Europe, the Irish round towers are thought to have functioned in part as bell towers. Famous medieval European examples include Bruges, Ypres, Ghent, perhaps the most famous European free-standing bell tower, however, is the so-called Leaning Tower of Pisa, which is the campanile of the Duomo di Pisa in Pisa, Italy. In 1999 thirty-two Belgian belfries were added to the UNESCOs list of World Heritage Sites, in 2005 this list was extended with one Belgian and twenty-three Northern French belfries and is since known as Belfries of Belgium and France. In the Middle Ages, cities sometimes kept their important documents in belfries, not all are on a large scale, the bell tower of Katúň, in Slovakia, is typical of the many more modest structures that were once common in country areas. Archaic wooden bell towers survive adjoining churches in Lithuania and as well as in parts of Poland
20.
Convention (norm)
–
A convention is a set of agreed, stipulated, or generally accepted standards, norms, social norms, or criteria, often taking the form of a custom. Certain types of rules or customs may become law and regulatory legislation may be introduced to formalize or enforce the convention, in a social context, a convention may retain the character of an unwritten law of custom. A convention is a selection from two or more alternatives, where the rule or alternative is agreed upon among participants. Often the word refers to unwritten customs shared throughout a community, for instance, it is conventional in many societies that strangers being introduced shake hands. The standardization of time is a convention based on the solar cycle or calendar. The extent to which justice is conventional is historically an important debate among philosophers, the nature of conventions has raised long-lasting philosophical discussion. Quine, Davidson, and David Lewis published influential writings on the subject, lewiss account of convention received an extended critique in Margaret Gilberts On Social Facts, where an alternative account is offered. Another view of convention comes from Ruth Millikans Language, A Biological Model, according to David Kalupahana, The Buddha described conventions — whether linguistic, social, political, moral, ethical, or even religious — as arising dependent on specific conditions. According to his paradigm, when conventions are considered absolute realities, they contribute to dogmatism and this does not mean that conventions should be absolutely ignored as unreal and therefore useless. Instead, according to Buddhist thought, a person adopts a middle way without holding conventions to be ultimate or ignoring them when they are fruitful. In sociology a social rule refers to any social convention commonly adhered to in a society and these rules are not written in law or otherwise formalized. In social constructionism there is a focus on social rules. It is argued that these rules are socially constructed, that these rules act upon every member of a society, sociologists representing symbolic interactionism argue that social rules are created through the interaction between the members of a society. The focus on active interaction highlights the fluid, shifting character of social rules and these are specific to the social context, a context that varies through time and place. That means a social rule changes over time within the same society, what was acceptable in the past may no longer be the case. Similarly, rules differ across space, what is acceptable in one society may not be so in another, Social rules reflect what is acceptable or normal behaviour in any situation. Michel Foucaults concept of discourse is closely related to rules as it offers a possible explanation how these rules are shaped. It is the rules that tell people what is normal behaviour for any specific category
21.
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
22.
Anchor escapement
–
In horology, the anchor escapement is a type of escapement used in pendulum clocks. The anchor escapement was so named because one of its parts is shaped vaguely like a ships anchor. When Clements clock appeared Hooke claimed the invention of the escapement, the earliest known anchor clock is Wadham College Clock, a tower clock built at Wadham College, Oxford, in 1670, probably by clockmaker Joseph Knibb. The anchor became the standard escapement used in almost all pendulum clocks, a variation without recoil called the deadbeat escapement was invented by Richard Towneley around 1675 and introduced by British clockmaker George Graham around 1715. This gradually superseded the recoil escapement and is used in all modern pendulum clocks with anchor escapements. On the two arms of the anchor are curved flat faces which the teeth of the escape wheel push against, called pallets. Each time one pallet moves away from the wheel, releasing a tooth, the wheel turns and a tooth on the other side catches on the other pallet. Then the tooth slides off the end of the pallet, beginning the cycle again, neither the anchor escapement nor the deadbeat form, below, are self-starting. The pendulum must be given a swing to get them going, the backward motion of the escape wheel during part of the cycle, called recoil, is one of the disadvantages of the anchor escapement. It can also cause the points of the wheel teeth to dig into the pallet surface. The teeth are slanted backward, opposite the direction of rotation, another reason the escape wheel teeth are slanted backward is as a safety measure. If the clock is moved without immobilising the pendulum, the swinging of the pendulum can cause the anchor pallets to collide violently with the escape wheel. The slanted teeth ensure that the faces of the anchor pallets hit the sides of the teeth first. The deadbeat escapement doesnt have recoil, one way to determine whether an antique pendulum clock has an anchor or deadbeat escapement is to observe the second hand. If it moves backward slightly after every tick, showing recoil, the shaft of the anchor, called the crutch ends in a fork which embraces the shaft of the pendulum, giving it transverse impulses. The pendulum rod is hung from a straight suspension spring attached to a sturdy support directly behind the anchor. The pivot of the anchor is aligned with the point of the spring. This arrangement results in a more stable pendulum support than simply suspending the pendulum directly from the anchor, the anchor is very tolerant of variations in its geometry, so its shape varied widely
23.
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
24.
Gnomon
–
A gnomon is the part of a sundial that casts a shadow. The term has come to be used for a variety of purposes in mathematics, a painted stick from 2300 BCE found in China is the oldest known gnomon. Anaximander is credited with introducing this Babylonian instrument to the Greeks, oenopides used the phrase drawn gnomon-wise to describe a line drawn perpendicular to another. Later, the term was used for an L-shaped instrument like a steel square used to right angles. This shape may explain its use to describe a shape formed by cutting a square from a larger one. Euclid extended the term to the figure formed by removing a similar parallelogram from a corner of a larger parallelogram. Indeed, the gnomon is the increment between two successive figurate numbers, including square and triangular numbers, hero of Alexandria defined a gnomon as that which, when added to an entity, makes a new entity similar to the starting entity. In this sense Theon of Smyrna used it to describe a number added to a polygonal number produces the next one of the same type. The most common use in this sense is an odd integer especially when seen as a number between square numbers. Perforated gnomons projecting an image of the sun were described in the Chinese Zhoubi Suanjing writings. The location of the circle can be measured to tell the time of day. In Arab and European cultures its invention was later attributed to Egyptian astronomer. With markings on the floor it tells the time of each midday as well as the date of the summer solstice. Italian mathematician, engineer, astronomer and geographer Leonardo Ximenes reconstructed the gnomon according to his new measurements in 1756, in the northern hemisphere, the shadow-casting edge of a sundial gnomon is normally oriented so that it points north and is parallel to the rotation axis of the Earth. That is, it is inclined to the horizontal at an angle equals the latitude of the sundials location. At present, such a gnomon should thus point almost precisely at Polaris, on some sundials, the gnomon is vertical. These were usually used in times for observing the altitude of the Sun. The style is the part of the gnomon that casts the shadow and this can change as the sun moves
25.
Decimal time
–
Decimal time is the representation of the time of day using units which are decimally related. Therefore, it becomes simpler to interpret a timestamp and to perform conversions, for instance,1,23,00 is 1 decimal hour and 23 decimal minutes, or 1.23 hours, or 123 minutes,3 hours is 300 minutes or 30,000 seconds. It also adjusts well to digital time representation using epochs, in that the time representation can be used directly both for computation and for user-facing display. Decimal time was used in China throughout most of its history alongside duodecimal time, the midnight-to-midnight day was divided both into 12 double hours and also into 10 shi /100 ke by the 1st millennium BC. Other numbers of ke per day were used during three periods,120 ke from 5–3 BC,96 ke from 507–544 CE, and 108 ke from 544–565. Several of the roughly 50 Chinese calendars also divided each ke into 100 fen, in 1280, the Shoushi calendar further subdivided each fen into 100 miao, creating a complete decimal time system of 100 ke,100 fen and 100 miao. In 1788, Claude Boniface Collignon proposed dividing the day into 10 hours or 1000 minutes, each new hour into 100 minutes, each new minute into 1000 seconds, further, the new tierce would be divided into 1000 quatierces, which he called microscopic points of time. He also suggested a week of 10 days and dividing the year into 10 solar months, decimal time was officially introduced during the French Revolution. Jean-Charles de Borda made a proposal for decimal time on November 5,1792, the National Convention issued a decree on 5 October 1793, XI. Le jour, de minuit à minuit, est divisé en dix parties, chaque partie en dix autres, the day, from midnight to midnight, is divided into ten parts, each part into ten others, and so forth until the smallest measurable portion of duration. These parts were named on 24 November 1793, the primary divisions were called hours, and they added, La centième partie de lheure est appelée minute décimale, la centième partie de la minute est appelée seconde décimale. The hundredth part of the hour is called decimal minute, the part of the minute is called decimal second. Thus, midnight was called either dix heures or zero heures, noon was called cinq heures, Units were either written out or abbreviated, such as 8 h.72 m. Sometimes in official records, decimal hours were divided into tenths, or décimes, instead of minutes. In spite of this, decimal time was used in cities, including Marseille and Toulouse. On the Palace of the Tuileries in Paris, two of the four clock faces displayed decimal time until at least 1801, the mathematician and astronomer Pierre-Simon Laplace had a decimal watch made for him, and used decimal time in his work, in the form of fractional days. Because of this, astronomers still use decimal time, the start of each year was determined according to the day of the autumnal equinox, in relation to true or apparent solar time at the Paris Observatory. Decimal time would also have been reckoned according to apparent solar time, depending on the location it was observed, at the International Meridian Conference of 1884, the following resolution was proposed by the French delegation and passed nem con, VII
26.
French Revolution
–
Through the Revolutionary Wars, it unleashed a wave of global conflicts that extended from the Caribbean to the Middle East. Historians widely regard the Revolution as one of the most important events in human history, the causes of the French Revolution are complex and are still debated among historians. Following the Seven Years War and the American Revolutionary War, the French government was deeply in debt, Years of bad harvests leading up to the Revolution also inflamed popular resentment of the privileges enjoyed by the clergy and the aristocracy. Demands for change were formulated in terms of Enlightenment ideals and contributed to the convocation of the Estates-General in May 1789, a central event of the first stage, in August 1789, was the abolition of feudalism and the old rules and privileges left over from the Ancien Régime. The next few years featured political struggles between various liberal assemblies and right-wing supporters of the intent on thwarting major reforms. The Republic was proclaimed in September 1792 after the French victory at Valmy, in a momentous event that led to international condemnation, Louis XVI was executed in January 1793. External threats closely shaped the course of the Revolution, internally, popular agitation radicalised the Revolution significantly, culminating in the rise of Maximilien Robespierre and the Jacobins. Large numbers of civilians were executed by revolutionary tribunals during the Terror, after the Thermidorian Reaction, an executive council known as the Directory assumed control of the French state in 1795. The rule of the Directory was characterised by suspended elections, debt repudiations, financial instability, persecutions against the Catholic clergy, dogged by charges of corruption, the Directory collapsed in a coup led by Napoleon Bonaparte in 1799. The modern era has unfolded in the shadow of the French Revolution, almost all future revolutionary movements looked back to the Revolution as their predecessor. The values and institutions of the Revolution dominate French politics to this day, the French Revolution differed from other revolutions in being not merely national, for it aimed at benefiting all humanity. Globally, the Revolution accelerated the rise of republics and democracies and it became the focal point for the development of all modern political ideologies, leading to the spread of liberalism, radicalism, nationalism, socialism, feminism, and secularism, among many others. The Revolution also witnessed the birth of total war by organising the resources of France, historians have pointed to many events and factors within the Ancien Régime that led to the Revolution. Over the course of the 18th century, there emerged what the philosopher Jürgen Habermas called the idea of the sphere in France. A perfect example would be the Palace of Versailles which was meant to overwhelm the senses of the visitor and convince one of the greatness of the French state and Louis XIV. Starting in the early 18th century saw the appearance of the sphere which was critical in that both sides were active. In France, the emergence of the public sphere outside of the control of the saw the shift from Versailles to Paris as the cultural capital of France. In the 1750s, during the querelle des bouffons over the question of the quality of Italian vs, in 1782, Louis-Sébastien Mercier wrote, The word court no longer inspires awe amongst us as in the time of Louis XIV
27.
French Republican Calendar
–
The revolutionary system was designed in part to remove all religious and royalist influences from the calendar, and was part of a larger attempt at decimalisation in France. Sylvain Maréchal, prominent anticlerical atheist, published the first edition of his Almanach des Honnêtes-gens in 1788, on pages 14–15 appears a calendar, consisting of twelve months. The first month is Mars, ou Princeps, the last month is Février, the lengths of the months are the same, however, the 10th, 20th, and 30th are singled out of each month as the end of a décade. Individual days were assigned, instead of to the saints, to people noteworthy for mostly secular achievements. Later editions of the almanac would switch to the Republican Calendar, the days of the French Revolution and Republic saw many efforts to sweep away various trappings of the ancien régime, some of these were more successful than others. The new Republican government sought to institute, among other reforms, a new social and legal system, a new system of weights and measures, and a new calendar. Amid nostalgia for the ancient Roman Republic, the theories of the Enlightenment were at their peak, natural constants, multiples of ten, and Latin as well as Old Greek derivations formed the fundamental blocks from which the new systems were built. The new calendar was created by a commission under the direction of the politician Charles-Gilbert Romme seconded by Claude Joseph Ferry and it is because of his position as rapporteur of the commission that the creation of the republican calendar is attributed to Romme. The calendar is called the French Revolutionary Calendar because it was created during the Revolution. Indeed, there was initially a debate as to whether the calendar should celebrate the Great Revolution, which began in July 1789, or the Republic, immediately following 14 July 1789, papers and pamphlets started calling 1789 year I of Liberty and the following years II and III. It was in 1792, with the problem of dating financial transactions. Originally, the choice of epoch was either 1 January 1789 or 14 July 1789, after some hesitation the assembly decided on 2 January 1792 that all official documents would use the era of Liberty and that the year IV of Liberty started on 1 January 1792. This usage was modified on 22 September 1792 when the Republic was proclaimed, the establishment of the Republic was used as the epochal date for the calendar, therefore, the calendar commemorates the Republic, not the Revolution. In France, it is known as the calendrier républicain as well as the calendrier révolutionnaire, the Revolution is usually considered to have ended with the coup of 18 Brumaire in Year VIII. The French Republic ended with the coronation of Napoleon I as Empereur des Français on 11 Frimaire, Year XIII, French coins of the period naturally used this calendar. Many show the year in Arabic numbers, although Roman numerals were used on some issues, Year 11 coins typically have a XI date to avoid confusion with the Roman II. Napoléon finally abolished the calendar with effect from 1 January 1806, however, it was used again during the brief Paris Commune, 6–23 May 1871. These documents have kept their original dates for legal accuracy and citation purposes, years appear in writing as Roman numerals, with epoch 22 September 1792, the beginning of the Republican Era
28.
Vitreous enamel
–
Vitreous enamel, also called porcelain enamel, is a material made by fusing powdered glass to a substrate by firing, usually between 750 and 850 °C. The powder melts, flows, and then hardens to a smooth, durable vitreous coating on metal, so in technical terms fired enamelware is an integrated layered composite of glass and metal. Enamelling is an old and widely adopted technology, for most of its history mainly used in jewelry, enamelled and enamelling are the preferred spellings in British English, while enameled and enameling are preferred in American English. The term enamel is most often restricted to work on metal, enamelled glass is also called painted, and overglaze decoration to pottery is often called enamelling. The word enamel comes from the Old High German word smelzan via the Old French esmail, or from a Latin word smaltum, used as a noun, an enamel is usually a small decorative object coated with enamel. Since the 19th century the term also to industrial materials and many metal consumer objects, such as some cooking vessels, dishwashers, laundry machines, sinks. The ancient Egyptians applied enamels to stone objects, pottery, and sometimes jewellery, the ancient Greeks, Celts, Georgians, and Chinese also used enamel on metal objects. Enamel powder could be produced in two ways, either by powdering coloured glass, or by mixing colourless glass powder with pigments such as a metallic oxide, designs were either painted freehand or over the top of outline incisions, and the technique probably originated in metalworking. Once painted, enamelled glass vessels needed to be fired at a high enough to melt the applied powder. Ancient Persians used this method for colouring and ornamenting the surface of metals by fusing over it brilliant colours that are decorated in an intricate design and called it Meenakari. Gold has been used traditionally for Meenakari Jewellery as it holds the enamel better, lasts longer, initially, the work of Meenakari often went unnoticed as this art was traditionally used as a backing for the famous kundan or stone-studded jewellery. This also allowed the wearer to reverse the jewellery as also promised a special joy in the secret of the hidden design, the Byzantine enamel style was widely adopted by the barbarian peoples of Migration Period northern Europe. The Byzantines then began to use cloisonné more freely to create images, the champlevé technique was considerably easier and very widely practiced in the Romanesque period. In Gothic art the finest work is in basse-taille and ronde-bosse techniques, from either Byzantium or the Islamic world, the cloisonné technique reached China in the 13-14th centuries. The first written reference to cloisonné is in a book from 1388, cloisonné remained very popular in China until the 19th century and is still produced today. Starting from the century, the Japanese also produced large quantities of very high technical quality. A resurgence in enamel-based art took place near the end of the 20th century in the Soviet Union, led by artists like Alexei Maximov, in Australia, abstract artist Bernard Hesling brought the style into prominence with his variously sized steel plates. Enamel was first applied commercially to sheet iron and steel in Austria, industrialization increased as the purity of raw materials increased and costs decreased
29.
Clock position
–
A clock position is the relative direction of an object described using the analogy of a 12-hour clock to describe angles and directions. One imagines a clock face lying either upright or flat in front of oneself, using this analogy,12 oclock means ahead or above,3 oclock means to the right,6 oclock means behind or below, and 9 oclock means to the left. The other eight hours refer to directions that are not directly in line with the four cardinal directions. In aviation, a clock refers to a horizontal direction. 6 oclock high means behind and above the horizon, while 12 oclock low means ahead, the 1949 movie Twelve OClock High takes its title from the system. In this case the position would be ahead and above the horizon, the phrase on your six refers to the system, six referring to the six oclock or following position. Clock angle problem Port and starboard Hour angle
30.
International Standard Book Number
–
The International Standard Book Number is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation of a book, for example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, the method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9-digit Standard Book Numbering created in 1966, the 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108. Occasionally, a book may appear without a printed ISBN if it is printed privately or the author does not follow the usual ISBN procedure, however, this can be rectified later. Another identifier, the International Standard Serial Number, identifies periodical publications such as magazines, the ISBN configuration of recognition was generated in 1967 in the United Kingdom by David Whitaker and in 1968 in the US by Emery Koltay. The 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108, the United Kingdom continued to use the 9-digit SBN code until 1974. The ISO on-line facility only refers back to 1978, an SBN may be converted to an ISBN by prefixing the digit 0. For example, the edition of Mr. J. G. Reeder Returns, published by Hodder in 1965, has SBN340013818 -340 indicating the publisher,01381 their serial number. This can be converted to ISBN 0-340-01381-8, the check digit does not need to be re-calculated, since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with Bookland European Article Number EAN-13s. An ISBN is assigned to each edition and variation of a book, for example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, a 13-digit ISBN can be separated into its parts, and when this is done it is customary to separate the parts with hyphens or spaces. Separating the parts of a 10-digit ISBN is also done with either hyphens or spaces, figuring out how to correctly separate a given ISBN number is complicated, because most of the parts do not use a fixed number of digits. ISBN issuance is country-specific, in that ISBNs are issued by the ISBN registration agency that is responsible for country or territory regardless of the publication language. Some ISBN registration agencies are based in national libraries or within ministries of culture, in other cases, the ISBN registration service is provided by organisations such as bibliographic data providers that are not government funded. In Canada, ISBNs are issued at no cost with the purpose of encouraging Canadian culture. In the United Kingdom, United States, and some countries, where the service is provided by non-government-funded organisations. Australia, ISBNs are issued by the library services agency Thorpe-Bowker
31.
Integrated Authority File
–
The Integrated Authority File or GND is an international authority file for the organisation of personal names, subject headings and corporate bodies from catalogues. It is used mainly for documentation in libraries and increasingly also by archives, the GND is managed by the German National Library in cooperation with various regional library networks in German-speaking Europe and other partners. The GND falls under the Creative Commons Zero license, the GND specification provides a hierarchy of high-level entities and sub-classes, useful in library classification, and an approach to unambiguous identification of single elements. It also comprises an ontology intended for knowledge representation in the semantic web, available in the RDF format
.jpg)
.jpg)
