Misplaced Pages

#957042

168-560: An hour ( symbol : h ; also abbreviated hr ) is a unit of time historically reckoned as 1 ⁄ 24 of a day and defined contemporarily as exactly 3,600 seconds ( SI ). There are 60 minutes in an hour, and 24 hours in a day. The hour was initially established in the ancient Near East as a variable measure of 1 ⁄ 12 of the night or daytime . Such seasonal hours , also known as temporal hours or unequal hours , varied by season and latitude . Equal hours or equinoctial hours were taken as 1 ⁄ 24 of

336-534: A Carthaginian army there. This was the first time a European force had invaded the region. After this war he controlled most of south-east Sicily and had himself proclaimed king, in imitation of the Hellenistic monarchs of the east. Agathocles then invaded Italy ( c.  300 BC ) in defense of Tarentum against the Bruttians and Romans , but was unsuccessful. Greeks in pre-Roman Gaul were mostly limited to

504-406: A Hellenistic period is a 19th-century concept, and did not exist in ancient Greece . Although words related in form or meaning, e.g. Hellenist ( Ancient Greek : Ἑλληνιστής , Hellēnistēs ), have been attested since ancient times, it has been attributed to the 19th century German historian Johann Gustav Droysen , who in his classic work Geschichte des Hellenismus ( History of Hellenism ), coined

672-648: A carefully neutral posture and acting to preserve the balance of power between the major Hellenistic kingdoms. Initially, Rhodes had very close ties with the Ptolemaic kingdom. Rhodes later became a Roman ally against the Seleucids, receiving some territory in Caria for their role in the Roman–Seleucid War (192–188 BC). Rome eventually turned on Rhodes and annexed the island as a Roman province. The west Balkan coast

840-466: A coherent system the units of force , energy , and power are chosen so that the equations hold without the introduction of unit conversion factors. Once a set of coherent units has been defined, other relationships in physics that use this set of units will automatically be true. Therefore, Einstein 's mass–energy equation , E = mc , does not require extraneous constants when expressed in coherent units. The CGS system had two units of energy,

1008-562: A combined Theban and Athenian army at the Battle of Chaeronea after a decade of desultory conflict. In the aftermath, Philip formed the League of Corinth , effectively bringing the majority of Greece under his direct sway. He was elected Hegemon of the league, and a campaign against the Achaemenid Empire of Persia was planned. However in 336 BC, while this campaign was in its early stages, he

1176-828: A commission to implement this new standard alone, and in 1799, the new system was launched in France. The units of the metric system, originally taken from observable features of nature, are now defined by seven physical constants being given exact numerical values in terms of the units. In the modern form of the International System of Units (SI), the seven base units are: metre for length, kilogram for mass, second for time, ampere for electric current, kelvin for temperature, candela for luminous intensity and mole for amount of substance. These, together with their derived units, can measure any physical quantity. Derived units may have their own unit name, such as

1344-470: A common Attic -based Greek dialect, known as Koine Greek , which became the lingua franca throughout the ancient world. During the Hellenistic period, Greek cultural influence reached its peak in the Mediterranean and beyond. Prosperity and progress in the arts , literature , theatre , architecture , music , mathematics , philosophy , and science characterize the era. The Hellenistic period saw

1512-585: A decimal multiple of it; and the unit of mass should be the gram or a decimal multiple of it. Metric systems have evolved since the 1790s, as science and technology have evolved, in providing a single universal measuring system. Before and in addition to the SI, other metric systems include: the MKS system of units and the MKSA systems, which are the direct forerunners of the SI; the centimetre–gram–second (CGS) system and its subtypes,

1680-600: A fleet. Ptolemy invaded Syria and defeated Antigonus' son, Demetrius Poliorcetes , in the Battle of Gaza of 312 BC which allowed Seleucus to secure control of Babylonia , and the eastern satrapies. In 310 BC, Cassander had young King Alexander IV and his mother Roxana murdered, ending the Argead dynasty which had ruled Macedon for several centuries. Antigonus then sent his son Demetrius to regain control of Greece. In 307 BC he took Athens, expelling Demetrius of Phaleron , Cassander's governor, and proclaiming

1848-450: A fourth base unit, the various anomalies in electromagnetic systems could be resolved. The metre–kilogram–second– coulomb (MKSC) and metre–kilogram–second– ampere (MKSA) systems are examples of such systems. The metre–tonne–second system of units (MTS) was based on the metre, tonne and second – the unit of force was the sthène and the unit of pressure was the pièze . It was invented in France for industrial use and from 1933 to 1955

SECTION 10

#1732837803958

2016-499: A league against Cassander's Macedon. The decisive engagement of the war came when Lysimachus invaded and overran much of western Anatolia, but was soon isolated by Antigonus and Demetrius near Ipsus in Phrygia . Seleucus arrived in time to save Lysimachus and utterly crushed Antigonus at the Battle of Ipsus in 301 BC. Seleucus' war elephants proved decisive; Antigonus was killed, and Demetrius fled back to Greece to attempt to preserve

2184-501: A liberator than a conqueror. In addition, much of the area conquered would continue to be ruled by the Diadochi , Alexander's generals and successors. Initially, the whole empire was divided among them; however, some territories were lost relatively quickly or only remained nominally under Macedonian rule. After 200 years, only much reduced and rather degenerate states remained, until the conquest of Ptolemaic Egypt by Rome. When Alexander

2352-467: A metre. This is unlike older systems of units in which the ratio between the units for longer and shorter distances varied: there are 12 inches in a foot, but the number of 5,280 feet in a mile is not a power of 12. For many everyday applications, the United States has resisted the adoption of a decimal-based system, continuing to use "a conglomeration of basically incoherent measurement systems ". In

2520-618: A new agreement with Antipater at the Treaty of Triparadisus . Antipater was made regent of the Empire, and the two kings were moved to Macedon. Antigonus remained in charge of Asia Minor, Ptolemy retained Egypt, Lysimachus retained Thrace and Seleucus I controlled Babylon . The second Diadochi war began following the death of Antipater in 319 BC. Passing over his own son, Cassander , Antipater had declared Polyperchon his successor as Regent . Cassander rose in revolt against Polyperchon (who

2688-556: A number of different ways over the centuries. The SI system originally derived its terminology from the metre, kilogram, second system of units , though the definitions of the fundamental SI units have been changed to depend only on constants of nature. Other metric system variants include the centimetre–gram–second system of units , the metre–tonne–second system of units , and the gravitational metric system . Each of these has some unique named units (in addition to unaffiliated metric units ) and some are still in use in certain fields. In

2856-500: A positive or negative leap second , effectively making it appear to last 3,599 or 3,601 seconds, in order to keep UTC within 0.9 seconds of UT1 , the latter of which is based on measurements of the mean solar day . Hour is a development of the Anglo-Norman houre and Middle English ure , first attested in the 13th century. It displaced tide tīd , 'time' and stound stund , span of time . The Anglo-Norman term

3024-420: A representative quantity is defined as a base unit of measure. The definition of base units has increasingly been realised in terms of fundamental natural phenomena, in preference to copies of physical artefacts. A unit derived from the base units is used for expressing quantities of dimensions that can be derived from the base dimensions of the system—e.g., the square metre is the derived unit for area, which

3192-406: A second greater than 1; the non-SI units of minute , hour and day are used instead. On the other hand, prefixes are used for multiples of the non-SI unit of volume, the litre (l, L) such as millilitres (ml). Each variant of the metric system has a degree of coherence—the derived units are directly related to the base units without the need for intermediate conversion factors. For example, in

3360-700: A second. In medieval Europe, the Roman hours continued to be marked on sundials but the more important units of time were the canonical hours of the Orthodox and Catholic Church . During daylight, these followed the pattern set by the three-hour bells of the Roman markets , which were succeeded by the bells of local churches. They rang prime at about 6   am, terce at about 9   am, sext at noon, nones at about 3   pm, and vespers at either 6   pm or sunset . Matins and lauds precede these irregularly in

3528-415: A secondary unit computed as precisely 3,600 seconds. However, an hour of Coordinated Universal Time (UTC), used as the basis of most civil time, has lasted 3,601 seconds 27 times since 1972 in order to keep it within 0.9 seconds of universal time , which is based on measurements of the mean solar day at 0° longitude . The addition of these seconds accommodates the very gradual slowing of the rotation of

SECTION 20

#1732837803958

3696-474: A standard without reliance on an artefact held by another country. In practice, such realisation is done under the auspices of a mutual acceptance arrangement . In 1791 the commission originally defined the metre based on the size of the earth, equal to one ten-millionth of the distance from the equator to the North Pole. In the SI, the standard metre is now defined as exactly 1 ⁄ 299 792 458 of

3864-435: A standing army of mercenaries and a small core of Greco-Macedonian settlers. Promotion of immigration from Greece was important in the establishment of this system. Hellenistic monarchs ran their kingdoms as royal estates and most of the heavy tax revenues went into the military and paramilitary forces which preserved their rule from any kind of revolution. Macedonian and Hellenistic monarchs were expected to lead their armies on

4032-526: A summary of Arrian 's Events after Alexander , by Photios I of Constantinople . Lesser supplementary sources include Curtius Rufus , Pausanias , Pliny , and the Byzantine encyclopedia the Suda . In the field of philosophy, Diogenes Laërtius ' Lives and Opinions of Eminent Philosophers is the main source; works such as Cicero 's De Natura Deorum also provide some further detail of philosophical schools in

4200-565: Is Athens , which had been decisively defeated by Antipater in the Lamian war (323–322 BC) and had its port in the Piraeus garrisoned by Macedonian troops who supported a conservative oligarchy . After Demetrius Poliorcetes captured Athens in 307 BC and restored the democracy , the Athenians honored him and his father Antigonus by placing gold statues of them on the agora and granting them

4368-615: Is "certain" this duodecimal division of the night followed the adoption of the Egyptian civil calendar , usually placed c.  2800   BC on the basis of analyses of the Sothic cycle , but a lunar calendar presumably long predated this and also would have had 12 months in each of its years. The coffin diagrams show that the Egyptians took note of the heliacal risings of 36 stars or constellations (now known as " decans "), one for each of

4536-411: Is derived from length. These derived units are coherent , which means that they involve only products of powers of the base units, without any further factors. For any given quantity whose unit has a name and symbol, an extended set of smaller and larger units is defined that are related by factors of powers of ten. The unit of time should be the second ; the unit of length should be either the metre or

4704-470: Is expressed in g/cm , force expressed in dynes and mechanical energy in ergs . Thermal energy was defined in calories , one calorie being the energy required to raise the temperature of one gram of water from 15.5 °C to 16.5 °C. The meeting also recognised two sets of units for electrical and magnetic properties – the electrostatic set of units and the electromagnetic set of units. The CGS units of electricity were cumbersome to work with. This

4872-460: Is now used to count quarter-hours, rather than a separate unit. As with the Egyptian night and daytime hours, the division of the day into 12 shi has been credited to the example set by the rough number of lunar cycles in a solar year, although the 12-year Jovian orbital cycle was more important to traditional Chinese and Babylonian reckoning of the zodiac. In Thailand , Laos , and Cambodia ,

5040-487: Is typically expressed in English in terms of hours. Whole hours on a 12-hour clock are expressed using the contracted phrase o'clock , from the older of the clock . (10 am and 10 pm are both read as "ten o'clock".) Hours on a 24-hour clock ("military time") are expressed as "hundred" or "hundred hours". (1000 is read "ten hundred" or "ten hundred hours"; 10 pm would be "twenty-two hundred".) Fifteen and thirty minutes past

5208-759: The Venus de Milo . A form of Hellenistic architecture arose which especially emphasized the building of grand monuments and ornate decorations, as exemplified by structures such as the Pergamon Altar . The religious sphere of Greek religion expanded through syncretic facets to include new gods such as the Greco-Egyptian Serapis , eastern deities such as Attis and Cybele , and a syncretism between Hellenistic culture and Buddhism in Bactria and Northwest India . Scholars and historians are divided as to which event signals

Hour - Misplaced Pages Continue

5376-584: The Avogadro number number of specified molecules, was added along with several other derived units. The system was promulgated by the General Conference on Weights and Measures (French: Conférence générale des poids et mesures – CGPM) in 1960. At that time, the metre was redefined in terms of the wavelength of a spectral line of the krypton-86 atom (krypton-86 being a stable isotope of an inert gas that occurs in undetectable or trace amounts naturally), and

5544-530: The CGS electrostatic (cgs-esu) system, the CGS electromagnetic (cgs-emu) system, and their still-popular blend, the Gaussian system ; the metre–tonne–second (MTS) system; and the gravitational metric systems , which can be based on either the metre or the centimetre, and either the gram, gram-force, kilogram or kilogram-force. The SI has been adopted as the official system of weights and measures by nearly all nations in

5712-526: The Diadochi wars broke out when Perdiccas planned to marry Alexander's sister Cleopatra and began to question Antigonus I Monophthalmus ' leadership in Asia Minor . Antigonus fled for Greece, and then, together with Antipater and Craterus (the satrap of Cilicia who had been in Greece fighting the Lamian war ) invaded Anatolia . The rebels were supported by Lysimachus , the satrap of Thrace and Ptolemy,

5880-466: The Earth . In modern life, the ubiquity of clocks and other timekeeping devices means that segmentation of days according to their hours is commonplace. Most forms of employment , whether wage or salaried labour, involve compensation based upon measured or expected hours worked. The fight for an eight-hour day was a part of labour movements around the world. Informal rush hours and happy hours cover

6048-633: The Greco-Bactrian kingdom ). It can be argued that some of the changes across the Macedonian Empire after Alexander's conquests and during the rule of the Diadochi would have occurred without the influence of Greek rule. As mentioned by Peter Green , numerous factors of conquest have been merged under the term Hellenistic period . Specific areas conquered by Alexander's invading army, including Egypt and areas of Asia Minor and Mesopotamia "fell" willingly to conquest and viewed Alexander as more of

6216-571: The Greek colonies in Illyria. Illyrians imported weapons and armor from the ancient Greeks (such as the Illyrian type helmet , originally a Greek type) and also adopted the ornamentation of ancient Macedon on their shields and their war belts (a single one has been found, dated 3rd century BC at modern Selcë e Poshtme , a part of Macedon at the time under Philip V of Macedon ). The Odrysian Kingdom

6384-584: The International System of Units (SI). The International System of Units is the modern metric system. It is based on the metre–kilogram–second–ampere (MKSA) system of units from early in the 20th century. It also includes numerous coherent derived units for common quantities like power (watt) and irradience (lumen). Electrical units were taken from the International system then in use. Other units like those for energy (joule) were modelled on those from

6552-463: The Julian Date system, in which a new Julian Day begins at noon) is that the date doesn't change during a single night's observing. In the modern 12-hour clock , counting the hours starts at midnight and restarts at noon. Hours are numbered 12, 1, 2, ..., 11. Solar noon is always close to 12 noon (ignoring artificial adjustments due to time zones and daylight saving time ), differing according to

6720-594: The Macedonian conquest of the Achaemenid Empire in 330 BC and its disintegration shortly thereafter in the Partition of Babylon and subsequent Wars of the Diadochi , Hellenistic kingdoms were established throughout West Asia ( Seleucid Empire , Kingdom of Pergamon ), Northeast Africa ( Ptolemaic Kingdom ) and South Asia ( Greco-Bactrian Kingdom , Indo-Greek Kingdom ). This resulted in an influx of Greek colonists and

6888-464: The Mediterranean coast of Provence , France . The first Greek colony in the region was Massalia , which became one of the largest trading ports of Mediterranean by the 4th century BC with 6,000 inhabitants. Massalia was also the local hegemon , controlling various coastal Greek cities like Nice and Agde . The coins minted in Massalia have been found in all parts of Liguro-Celtic Gaul. Celtic coinage

Hour - Misplaced Pages Continue

7056-562: The Mètre des Archives and Kilogramme des Archives (or their descendants) as their base units, but differing in the definitions of the various derived units. In 1832, Gauss used the astronomical second as a base unit in defining the gravitation of the Earth, and together with the milligram and millimetre, this became the first system of mechanical units . He showed that the strength of a magnet could also be quantified in terms of these units, by measuring

7224-543: The Practical System of Electric Units , or QES (quad–eleventhgram–second) system, was being used. Here, the base units are the quad, equal to 10  m (approximately a quadrant of the Earth's circumference), the eleventhgram, equal to 10  g , and the second. These were chosen so that the corresponding electrical units of potential difference, current and resistance had a convenient magnitude. In 1901, Giovanni Giorgi showed that by adding an electrical unit as

7392-552: The Ptolemaic Kingdom , which might otherwise have been lost, has been preserved in papyrological documents. This is particularly noteworthy given the limited documentation available for their Seleucid counterparts. Ancient Greece had traditionally been a fractious collection of fiercely independent city-states. After the Peloponnesian War (431–404 BC), Greece had fallen under a Spartan hegemony , in which Sparta

7560-632: The Roman Republic against the Carthaginian Empire during the Second Punic War (218–201 BC). However, Emporion lost its political independence around 195 BC with the establishment of the Roman province of Hispania Citerior and by the 1st century BC had become fully Romanized in culture. The Hellenistic states of Asia and Egypt were run by an occupying imperial elite of Greco-Macedonian administrators and governors propped up by

7728-444: The determinative hieroglyph for "sun". Ancient China divided its day into 100 "marks" ( Chinese : 刻 , oc * kʰək , p kè ) running from midnight to midnight. The system is said to have been used since remote antiquity , credited to the legendary Yellow Emperor , but is first attested in Han -era water clocks and in the 2nd-century history of that dynasty . It

7896-403: The equation of time by as much as fifteen minutes either way. At the equinoxes sunrise is around 6 a.m. ( Latin : ante meridiem , before noon), and sunset around 6 p.m. ( Latin : post meridiem , after noon). In the modern 24-hour clock , counting the hours starts at midnight, and hours are numbered from 0 to 23. Solar noon is always close to 12:00, again differing according to

8064-486: The erg that was related to mechanics and the calorie that was related to thermal energy ; so only one of them (the erg) could bear a coherent relationship to the base units. Coherence was a design aim of SI, which resulted in only one unit of energy being defined – the joule . Maxwell's equations of electromagnetism contained a factor of 1 / ( 4 π ) {\displaystyle 1/(4\pi )} relating to steradians , representative of

8232-543: The hertz (cycles per second), newton (kg⋅m/s ), and tesla (1 kg⋅s ⋅A ) – or a shifted scale, in the case of degrees Celsius . Certain units have been officially accepted for use with the SI . Some of these are decimalised, like the litre and electronvolt , and are considered "metric". Others, like the astronomical unit are not. Ancient non-metric but SI-accepted multiples of time ( minute and hour ) and angle ( degree , arcminute , and arcsecond ) are sexagesimal (base 60). The "metric system" has been formulated in

8400-448: The watt (J/s) and lux (cd/m ), or may just be expressed as combinations of base units, such as velocity (m/s) and acceleration (m/s ). The metric system was designed to have properties that make it easy to use and widely applicable, including units based on the natural world, decimal ratios, prefixes for multiples and sub-multiples, and a structure of base and derived units. It is a coherent system , derived units were built up from

8568-525: The " Nesiotic League " of the Cyclades . These federations involved a central government which controlled foreign policy and military affairs, while leaving most of the local governing to the city states , a system termed sympoliteia . In states such as the Achaean league, this also involved the admission of other ethnic groups into the federation with equal rights, in this case, non- Achaeans . The Achean league

SECTION 50

#1732837803958

8736-455: The 16th century. The Islamic day begins at sunset. The first prayer of the day ( maghrib ) is to be performed between just after sunset and the end of twilight. Until 1968 Saudi Arabia used the system of counting 24 equal hours with the first hour starting at sunset. For many centuries, up to 1925, astronomers counted the hours and days from noon, because it was the easiest solar event to measure accurately. An advantage of this method (used in

8904-619: The Aegean (204–200 BC) and ignored Roman demands for non-intervention in Greece by invading Attica. In 198 BC, during the Second Macedonian War Philip was decisively defeated at Cynoscephalae by the Roman proconsul Titus Quinctius Flamininus and Macedon lost all its territories in Greece proper. Southern Greece was now thoroughly brought into the Roman sphere of influence , though it retained nominal autonomy. The end of Antigonid Macedon came when Philip V's son, Perseus,

9072-780: The Athenians in the Chremonidean War , and then against the Achaean League of Aratus of Sicyon . Under the Antigonids, Macedonia was often short on funds, the Pangaeum mines were no longer as productive as under Philip II, the wealth from Alexander's campaigns had been used up and the countryside pillaged by the Gallic invasion . A large number of the Macedonian population had also been resettled abroad by Alexander or had chosen to emigrate to

9240-616: The Great of the capital of the Roman Empire to Constantinople in AD 330. Though this scope of suggested dates demonstrates a range of academic opinion, a generally accepted date by most of scholarship has been that of 31/30 BC. The word originated from ancient Greek Ἑλληνιστής ( Hellēnistḗs , "one who uses the Greek language"), from Ἑλλάς ( Hellás , "Greece"); as if "Hellenist" + "ic". The idea of

9408-416: The Great died (10 June 323 BC), he left behind a sprawling empire that was composed of many essentially autonomous territories called satrapies . Without a chosen successor, there were immediate disputes among his generals as to who should be king of Macedon. These generals became known as the Diadochi ( Ancient Greek : Διάδοχοι , Diadokhoi , meaning "Successors"). Meleager and the infantry supported

9576-691: The Greek world, making the endless conflicts between the cities that had marked the 5th and 4th centuries BC seem petty and unimportant. It led to a steady emigration, particularly of the young and ambitious, to the new Greek empires in the east. Many Greeks migrated to Alexandria , Antioch , and the many other new Hellenistic cities founded in Alexander's wake, as far away as modern Afghanistan and Pakistan . Independent city states were unable to compete with Hellenistic kingdoms and were usually forced to ally themselves to one of them for defense, giving honors to Hellenistic rulers in return for protection. One example

9744-620: The Greeks during the 8th century BC. In 4th-century BC Sicily the leading Greek city and hegemon was Syracuse . During the Hellenistic period the leading figure in Sicily was Agathocles of Syracuse (361–289 BC) who seized the city with an army of mercenaries in 317 BC. Agathocles extended his power throughout most of the Greek cities in Sicily, fought a long war with the Carthaginians , at one point invading Tunisia in 310 BC and defeating

9912-577: The Hellenistic period breaks off after the battle of Ipsus (301 BC). Another important source, Plutarch 's ( c.  AD 50  – c.  120 ) Parallel Lives although more preoccupied with issues of personal character and morality, outlines the history of important Hellenistic figures. Appian of Alexandria (late 1st century AD–before 165) wrote a history of the Roman empire that includes information of some Hellenistic kingdoms. Other sources include Justin 's (2nd century AD) epitome of Pompeius Trogus ' Historiae Philipicae and

10080-488: The Hellenistic period is Polybius of Megalopolis (c. 200–118), a statesman of the Achaean League until 168 BC when he was forced to go to Rome as a hostage. His Histories eventually grew to a length of forty books, covering the years 220 to 167 BC. The most important source after Polybius is Diodorus Siculus who wrote his Bibliotheca historica between 60 and 30 BC and reproduced some important earlier sources such as Hieronymus, but his account of

10248-486: The Hellenistic period. Inscriptions on stone or metal were commonly erected throughout the Greek world for public display, a practice which originated well before the time of Alexander the Great, but saw substantial expansion during the Hellenistic Period. The majority of these inscriptions are located on the Greek mainland , the Greek islands , and western Asia Minor . While they become increasingly rare towards

SECTION 60

#1732837803958

10416-582: The Hellenistic period. It became a center of culture and commerce, its coins were widely circulated and its philosophical schools became one of the best in the Mediterranean. After holding out for one year under siege by Demetrius Poliorcetes (305–304 BC), the Rhodians built the Colossus of Rhodes to commemorate their victory. They retained their independence by the maintenance of a powerful navy, by maintaining

10584-464: The Macedonians themselves were looked down upon as semi-barbaric by the rest of the Greeks. However, Macedon controlled a large area and had a relatively strong centralized government, in comparison to most Greek states. Philip II was a strong and expansionist king who took every opportunity to expand Macedonian territory. In 352 BC he annexed Thessaly and Magnesia . In 338 BC, Philip defeated

10752-460: The ancient Egyptian bureaucracy, highly centralized and focused on squeezing as much revenue out of the population as possible through tariffs, excise duties, fines, taxes, and so forth. A whole class of petty officials, tax farmers, clerks, and overseers made this possible. The Egyptian countryside was directly administered by this royal bureaucracy. External possessions such as Cyprus and Cyrene were run by strategoi , military commanders appointed by

10920-478: The appearance of the mechanical clock, which furthered the adoption of equal length hours. This is also the system used in Jewish law and frequently called " Talmudic hour " ( Sha'a Zemanit ) in a variety of texts. The Talmudic hour is one twelfth of time elapsed from sunrise to sunset, day hours therefore being longer than night hours in the summer; in winter they reverse. The Indic day began at sunrise. The term hora

11088-436: The base units using logical rather than empirical relationships while multiples and submultiples of both base and derived units were decimal-based and identified by a standard set of prefixes . The metric system is extensible, and new derived units are defined as needed in fields such as radiology and chemistry. For example, the katal , a derived unit for catalytic activity equivalent to one mole per second (1 mol/s),

11256-551: The beginning of the first hour, the middle of the day was at the end of the sixth hour and sunset at the end of the twelfth hour. This meant that the duration of hours varied with the season. In the Northern hemisphere, particularly in the more northerly latitudes, summer daytime hours were longer than winter daytime hours, each being one twelfth of the time between sunrise and sunset. These variable-length hours were variously known as temporal, unequal, or seasonal hours and were in use until

11424-485: The candidacy of Alexander's half-brother, Philip Arrhidaeus , while Perdiccas , the leading cavalry commander, supported waiting until the birth of Alexander's child by Roxana . After the infantry stormed the palace of Babylon , a compromise was arranged – Arrhidaeus (as Philip III) should become king and should rule jointly with Roxana's child, assuming that it was a boy (as it was, becoming Alexander IV ). Perdiccas himself would become regent ( epimeletes ) of

11592-442: The city free again. Demetrius now turned his attention to Ptolemy, defeating his fleet at the Battle of Salamis and taking control of Cyprus. In the aftermath of this victory, Antigonus took the title of king ( basileus ) and bestowed it on his son Demetrius Poliorcetes , the rest of the Diadochi soon followed suit. Demetrius continued his campaigns by laying siege to Rhodes and conquering most of Greece in 302 BC, creating

11760-541: The country, especially in the region of the Faiyum . Alexandria , a major center of Greek culture and trade, became his capital city. As Egypt's first port city, it became the main grain exporter in the Mediterranean. The Egyptians begrudgingly accepted the Ptolemies as the successors to the pharaohs of independent Egypt, though the kingdom went through several native revolts. Ptolemy I began to order monetary contributions from

11928-478: The crown. Under Ptolemy II , Callimachus , Apollonius of Rhodes , Theocritus , and a host of other poets including the Alexandrian Pleiad made the city a center of Hellenistic literature. Ptolemy himself was eager to patronise the library, scientific research and individual scholars who lived on the grounds of the library. He and his successors also fought a series of wars with the Seleucids, known as

12096-518: The day as measured from noon to noon; the minor seasonal variations of this unit were eventually smoothed by making it 1 ⁄ 24 of the mean solar day . Since this unit was not constant due to long term variations in the Earth's rotation, the hour was finally separated from the Earth's rotation and defined in terms of the atomic or physical second . In the modern metric system , hours are an accepted unit of time defined as 3,600 atomic seconds. However, on rare occasions an hour may incorporate

12264-603: The day was divided into 12 seasonal hours and the night into three or four night watches. By the Hellenistic period the night was also divided into 12 hours. The day-and-night ( νυχθήμερον ) was probably first divided into 24 hours by Hipparchus of Nicaea . The Greek astronomer Andronicus of Cyrrhus oversaw the construction of a horologion called the Tower of the Winds in Athens during

12432-580: The death of Pyrrhus, Epirus remained a minor power. In 233 BC the Aeacid royal family was deposed and a federal state was set up called the Epirote League . The league was conquered by Rome in the Third Macedonian War (171–168 BC). Antigonus II , a student of Zeno of Citium , spent most of his rule defending Macedon against Epirus and cementing Macedonian power in Greece, first against

12600-463: The definition of the International System of Units (SI) in the mid-20th century, under the oversight of an international standards body. Adopting the metric system is known as metrication . The historical evolution of metric systems has resulted in the recognition of several principles. A set of independent dimensions of nature is selected, in terms of which all natural quantities can be expressed, called base quantities. For each of these dimensions,

12768-421: The distance that light travels in a second . The metre can be realised by measuring the length that a light wave travels in a given time, or equivalently by measuring the wavelength of light of a known frequency. The kilogram was originally defined as the mass of one cubic decimetre of water at 4 °C, standardised as the mass of a man-made artefact of platinum–iridium held in a laboratory in France, which

12936-504: The division between night and day, and daily routines often began when light was sufficient. "Babylonian hours" divide the day and night into 24 equal hours, reckoned from the time of sunrise. They are so named from the false belief of ancient authors that the Babylonians divided the day into 24 parts, beginning at sunrise. In fact, they divided the day into 12 parts (called kaspu or "double hours") or into 60 equal parts. Sunrise marked

13104-401: The early days, multipliers that were positive powers of ten were given Greek-derived prefixes such as kilo- and mega- , and those that were negative powers of ten were given Latin-derived prefixes such as centi- and milli- . However, 1935 extensions to the prefix system did not follow this convention: the prefixes nano- and micro- , for example have Greek roots. During the 19th century

13272-488: The eastern regions, they are not entirely absent there, and they are most notably featured in public buildings and sanctuaries . The content of these inscriptions is diverse, encompassing royal correspondence addressed to cities or individuals, municipal and legal edicts, decrees commemorating rulers, officials, and individuals for their contributions, as well as laws, treaties, religious rulings, and dedications. Despite challenges in their interpretation, inscriptions are often

13440-668: The effect of tidal deceleration of the Earth by the Moon , which gradually lengthens the Earth's days. During the French Revolution , a general decimalisation of measures was enacted, including decimal time between 1794 and 1800. Under its provisions, the French hour ( French : heure ) was 1 ⁄ 10 of the day and divided formally into 100 decimal minutes ( minute décimale ) and informally into 10 tenths ( décime ). Mandatory use for all public records began in 1794, but

13608-417: The empire, and Meleager his lieutenant. Soon, however, Perdiccas had Meleager and the other infantry leaders murdered and assumed full control. The generals who had supported Perdiccas were rewarded in the partition of Babylon by becoming satraps of the various parts of the empire, but Perdiccas' position was shaky because, as Arrian writes, "everyone was suspicious of him, and he of them". The first of

13776-502: The end of the 24th hour. The clocks in church towers struck only from 1 to 12, thus only during night or early morning hours. This manner of counting hours had the advantage that everyone could easily know how much time they had to finish their day's work without artificial light . It was already widely used in Italy by the 14th century and lasted until the mid-18th century; it was officially abolished in 1755, or in some regions customary until

13944-463: The end of the Hellenistic era. There is a wide chronological range of proposed dates that have included the final conquest of the Greek heartlands by the expansionist Roman Republic in 146 BC following the Achaean War , the final defeat of the Ptolemaic Kingdom at the Battle of Actium in 31 BC, the end of the reign of the Roman emperor Hadrian in AD 138, and the move by the emperor Constantine

14112-522: The equation of time. At the equinoxes sunrise is around 06:00, and sunset around 18:00. 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 ( Dynasty IX ), diagrams of stars inside Egyptian coffin lids—variously known as "diagonal calendars" or "star clocks"—attest that there were exactly 12 of these. Clagett writes that it

14280-524: The export of Greek culture and language to these new realms, a breadth spanning as far as modern-day India. These new Greek kingdoms were also influenced by regional indigenous cultures, adopting local practices where deemed beneficial, necessary, or convenient. Hellenistic culture thus represents a fusion of the ancient Greek world with that of the Western Asian, Northeastern African, and Southwestern Asian worlds. The consequence of this mixture gave rise to

14448-425: The fact that electric charges and magnetic fields may be considered to emanate from a point and propagate equally in all directions, i.e. spherically. This factor made equations more awkward than necessary, and so Oliver Heaviside suggested adjusting the system of units to remove it. The basic units of the metric system, as originally defined, represented common quantities or relationships in nature. They still do –

14616-416: The field, along with a group of privileged aristocratic companions or friends ( hetairoi , philoi ) which dined and drank with the king and acted as his advisory council. The monarch was also expected to serve as a charitable patron of the people; this public philanthropy could mean building projects and handing out gifts but also promotion of Greek culture and religion. Ptolemy , a somatophylax , one of

14784-578: The first century BCE. This structure tracked a 24-hour day using both sundials and mechanical hour indicators. The canonical hours were inherited into early Christianity from Second Temple Judaism . By AD 60, the Didache recommends disciples to pray the Lord's Prayer three times a day; this practice found its way into the canonical hours as well. By the second and third centuries, such Church Fathers as Clement of Alexandria , Origen , and Tertullian wrote of

14952-547: The first hour started with the sunset Angelus bell (or at the end of dusk, i.e., half an hour after sunset, depending on local custom and geographical latitude). The hours were numbered from 1 to 24. For example, in Lugano, the sun rose in December during the 14th hour and noon was during the 19th hour; in June the sun rose during the 7th hour and noon was in the 15th hour. Sunset was always at

15120-427: The gates of each hour of the underworld, and Wadjet and the rearing cobra ( uraeus ) were also sometimes referenced as wnwt from their role protecting the dead through these gates. The Egyptian word for astronomer , used as a synonym for priest, was wnwty , "one of the wnwt ", as it were "one of the hours". The earliest forms of wnwt include one or three stars, with the later solar hours including

15288-459: The growing power and ambition of Antigonus. He began removing and appointing satraps as if he were king and also raided the royal treasuries in Ecbatana , Persepolis and Susa , making off with 25,000 talents . Seleucus was forced to flee to Egypt and Antigonus was soon at war with Ptolemy, Lysimachus, and Cassander. He then invaded Phoenicia , laid siege to Tyre , stormed Gaza and began building

15456-437: The hour divisions.) 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 ( c.  1350   BC), the priests at Karnak were using water clocks to determine the hours. These were filled to the brim at sunset and the hour determined by comparing the water level against one of its 12 gauges, one for each month of

15624-503: The hour into 60 minutes , each of 60 seconds ; this derives from Babylonian astronomy , where the corresponding terms denoted the time required for the Sun's apparent motion through the ecliptic to describe one minute or second of arc, respectively. In present terms, the Babylonian degree of time was thus four minutes long, the "minute" of time was thus four seconds long and the "second" 1/15 of

15792-449: The hour is expressed as "a quarter past" or "after" and "half past", respectively, from their fraction of the hour. Fifteen minutes before the hour may be expressed as "a quarter to", "of", "till", or "before" the hour. (9:45 may be read "nine forty-five" or "a quarter till ten".) In ancient Egypt the flooding of the Nile was, and still is, an important annual event, crucial for agriculture. It

15960-400: The huge territories Alexander had conquered became subject to a strong Greek influence ( Hellenization ) for the next two or three centuries, until the rise of Rome in the west, and of Parthia in the east. As the Greek and Levantine cultures mingled, the development of a hybrid Hellenistic culture began, and persisted even when isolated from the main centres of Greek culture (for instance, in

16128-421: The kilogram in terms of fundamental constants. A base quantity is one of a conventionally chosen subset of physical quantities, where no quantity in the subset can be expressed in terms of the others. A base unit is a unit adopted for expressing a base quantity. A derived unit is used for expressing any other quantity, and is a product of powers of base units. For example, in the modern metric system, length has

16296-643: The language of administration and of the nobility. The nobility also adopted Greek fashions in dress , ornament, and military equipment, spreading it to the other tribes. Thracian kings were among the first to be Hellenized . After 278 BC the Odrysians had a strong competitor in the Celtic Kingdom of Tylis ruled by the kings Comontorius and Cavarus , but in 212 BC they conquered their enemies and destroyed their capital. Southern Italy ( Magna Graecia ) and south-eastern Sicily had been colonized by

16464-593: The latest war between Macedon and the Greek leagues ( the Social War of 220–217 BC) to an end, and at this time he controlled all of Greece except Athens, Rhodes and Pergamum. In 215 BC Philip, with his eye on Illyria , formed an alliance with Rome's enemy Hannibal of Carthage , which led to Roman alliances with the Achaean League , Rhodes and Pergamum. The First Macedonian War broke out in 212 BC, and ended inconclusively in 205 BC. Philip continued to wage war against Pergamum and Rhodes for control of

16632-554: The length of their pendula ). The use of 24 hours for the entire day meant hours varied much less and the clocks needed to be adjusted only a few times a month. The minor irregularities of the apparent solar day were smoothed by measuring time using the mean solar day , using the Sun's movement along the celestial equator rather than along the ecliptic . The irregularities of this time system were so minor that most clocks reckoning such hours did not need adjustment. However, scientific measurements eventually became precise enough to note

16800-408: The metric system is the International System of Units (Système international d'unités or SI), in which all units can be expressed in terms of seven base units: the metre (m), kilogram (kg), second (s), ampere (A), kelvin (K), mole (mol), and candela (cd). These can be made into larger or smaller units with the use of metric prefixes . SI derived units are named combinations – such as

16968-419: The metric system, multiples and submultiples of units follow a decimal pattern. A common set of decimal-based prefixes that have the effect of multiplication or division by an integer power of ten can be applied to units that are themselves too large or too small for practical use. The prefix kilo , for example, is used to multiply the unit by 1000, and the prefix milli is to indicate a one-thousandth part of

17136-723: The mid-19th century. The system of Italian hours can be seen on a number of clocks in Europe, where the dial is numbered from 1 to 24 in either Roman or Arabic numerals. The St Mark's Clock in Venice, and the Orloj in Prague are famous examples. It was also used in Poland , Silesia , and Bohemia until the 17th century. Its replacement by the more practical division into twice twelve ( equinoctial ) hours (also called small clock or civic hours) began as early as

17304-510: The modern precisely defined quantities are refinements of definition and methodology, but still with the same magnitudes. In cases where laboratory precision may not be required or available, or where approximations are good enough, the original definitions may suffice. Basic units: metre , kilogram , second , ampere , kelvin , mole , and candela for derived units, such as Volts and Watts, see International System of Units . A number of different metric system have been developed, all using

17472-521: The morning hours; compline follows them irregularly before sleep; and the midnight office follows that. Vatican II ordered their reformation for the Catholic Church in 1963, though they continue to be observed in the Orthodox churches. When mechanical clocks began to be used to show hours of daylight or nighttime, their period needed to be changed every morning and evening (for example, by changing

17640-554: The native population did not always mix; the Greeks moved and brought their own culture, but interaction did not always occur. While a few fragments exist, there are no complete surviving historical works that date to the hundred years following Alexander's death. The works of the major Hellenistic historians Hieronymus of Cardia (who worked under Alexander, Antigonus I and other successors), Duris of Samos and Phylarchus , which were used by surviving sources , are all lost. The earliest and most credible surviving source for

17808-430: The new eastern Greek cities. Up to two-thirds of the population emigrated, and the Macedonian army could only count on a levy of 25,000 men, a significantly smaller force than under Philip II. Antigonus II ruled until his death in 239 BC. His son Demetrius II soon died in 229 BC, leaving a child (Philip V) as king, with the general Antigonus Doson as regent. Doson led Macedon to victory in

17976-440: The nightly intervals. These subdivisions of a day spread to Greece, and later to Rome. The ancient Greeks kept time differently than is done today. Instead of dividing the time between one midnight and the next into 24 equal hours, they divided the time from sunrise to sunset into 12 "seasonal hours" (their actual duration depending on season), and the time from sunset to the next sunrise again in 12 "seasonal hours". Initially, only

18144-430: The older CGS system, but scaled to be coherent with MKSA units. Two additional base units – the kelvin , which is equivalent to degree Celsius for change in thermodynamic temperature but set so that 0 K is absolute zero , and the candela , which is roughly equivalent to the international candle unit of illumination – were introduced. Later, another base unit, the mole , a unit of amount of substance equivalent to

18312-406: The only source available for understanding numerous events in Greek history. Papyrus served as the predominant medium for handwritten documents across the Hellenistic world, though its production was confined to Egypt . Due to Egypt's arid climate , papyrus manuscripts was almost exclusively preserved there as well. That being said, the different historical periods are not represented equally in

18480-597: The original, called the IPK . It became apparent that either the IPK or the replicas or both were deteriorating, and are no longer comparable: they had diverged by 50 μg since fabrication, so figuratively, the accuracy of the kilogram was no better than 5 parts in a hundred million or a relative accuracy of 5 × 10 . The revision of the SI replaced the IPK with an exact definition of the Planck constant as expressed in SI units, which defines

18648-591: The oscillations of a magnetised needle and finding the quantity of "magnetic fluid" that produces an acceleration of one unit when applied to a unit mass. The centimetre–gram–second system of units (CGS) was the first coherent metric system, having been developed in the 1860s and promoted by Maxwell and Thomson. In 1874, this system was formally promoted by the British Association for the Advancement of Science (BAAS). The system's characteristics are that density

18816-601: The other countries of the Sinosphere . The 12 shi supposedly began to be divided into 24 hours under the Tang , although they are first attested in the Ming -era Book of Yuan . In that work, the hours were known by the same earthly branches as the shi , with the first half noted as its "starting" and the second as "completed" or "proper" shi . In modern China, these are instead simply numbered and described as "little shi ". The modern ke

18984-569: The papyrological documents. Texts from the reign of Ptolemy I are notably scarce, while those from the reign of Ptolemy II are more frequently encountered, this is owing in part to the large quantities of papyri which were stuffed into human and animal mummies during his rule. Papyri have been classified into public and private documents, including literary texts, laws and regulations, official correspondence, petitions , records, and archives or collections of documents belonging to individuals of position and authority. Significant information about

19152-483: The people and, as a result, rewarded cities with high contributions with royal benefaction. This often resulted in the formation of a royal cult within the city. Reservations about this activity slowly dissipated as this worship of mortals was justified by the precedent of the worshipping of Greek heroes. The Ptolemies took on the traditions of the Egyptian Pharaohs , such as marrying their siblings ( Ptolemy II

19320-508: The practice of Morning and Evening Prayer, and of the prayers at the third, sixth and ninth hours. In the early church, during the night before every feast, a vigil was kept. The word "Vigils", at first applied to the Night Office, comes from a Latin source, namely the Vigiliae or nocturnal watches or guards of the soldiers. The night from six o'clock in the evening to six o'clock in the morning

19488-454: The practice of publicly announcing the daytime hours with a gong and the nighttime hours with a drum . It was abolished in Laos and Cambodia during their French occupation and is uncommon there now. The Thai system remains in informal use in the form codified in 1901 by King Chulalongkorn . The Vedas and Puranas employed units of time based on the sidereal day ( nakṣatra ahorātra ). This

19656-402: The prefix myria- , derived from the Greek word μύριοι ( mýrioi ), was used as a multiplier for 10 000 . When applying prefixes to derived units of area and volume that are expressed in terms of units of length squared or cubed, the square and cube operators are applied to the unit of length including the prefix, as illustrated below. Prefixes are not usually used to indicate multiples of

19824-557: 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 Ra 's solar barge 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. Two fire-spitting cobras were said to guard

19992-428: The remnants of his rule, thereby recapturing a rebellious Athens. Meanwhile, Lysimachus took over Ionia , Seleucus took Cilicia , and Ptolemy captured Cyprus . After Cassander's death in c.  298 BC , however, Demetrius, who still maintained a sizable loyal army and fleet, invaded Macedon, seized the Macedonian throne (294 BC) and conquered Thessaly and most of central Greece (293–291 BC). He

20160-511: The rise of New Comedy , Alexandrian poetry , translation efforts such as the Septuagint , and the philosophies of Stoicism , Epicureanism , and Pyrrhonism . In science, the works of the mathematician Euclid and the polymath Archimedes are exemplary. Sculpture during this period was characterized by intense emotion and dynamic movement, as seen in sculptural works like the Dying Gaul and

20328-478: The satrap of Egypt. Although Eumenes , satrap of Cappadocia , defeated the rebels in Asia Minor, Perdiccas himself was murdered by his own generals Peithon , Seleucus , and Antigenes (possibly with Ptolemy's aid) during his invasion of Egypt ( c.  21 May to 19 June, 320 BC). Ptolemy came to terms with Perdiccas's murderers, making Peithon and Arrhidaeus regents in his place, but soon these came to

20496-496: The second itself. As a consequence, the speed of light has now become an exactly defined constant, and defines the metre as 1 ⁄ 299,792,458 of the distance light travels in a second. The kilogram was defined by a cylinder of platinum-iridium alloy until a new definition in terms of natural physical constants was adopted in 2019. As of 2022, the range of decimal prefixes has been extended to those for 10 ( quetta– ) and 10 ( quecto– ). Hellenistic period After

20664-420: The seven bodyguards who served as Alexander the Great 's generals and deputies, was appointed satrap of Egypt after Alexander's death in 323 BC. In 305 BC, he declared himself King Ptolemy I, later known as "Soter" (saviour) for his role in helping the Rhodians during the siege of Rhodes . Ptolemy built new cities such as Ptolemais Hermiou in upper Egypt and settled his veterans throughout

20832-407: The spread of Greek culture was not the generalized phenomenon that the term implies. Some areas of the conquered world were more affected by Greek influences than others. The term Hellenistic also implies that the Greek populations were of majority in the areas in which they settled, but in many cases, the Greek settlers were actually the minority among the native populations. The Greek population and

21000-460: The standard metre artefact from 1889 was retired. Today, the International system of units consists of 7 base units and innumerable coherent derived units including 22 with special names. The last new derived unit, the katal for catalytic activity, was added in 1999. All the base units except the second are now defined in terms of exact and invariant constants of physics or mathematics, barring those parts of their definitions which are dependent on

21168-437: The telegraph or similar means to transfer a time signal in a split-second), this issue is much less relevant. Astrolabes , sundials , and astronomical clocks sometimes show the hour length and count using some of these older definitions and counting methods. In ancient and medieval cultures, the counting of hours generally started with sunrise. Before the widespread use of artificial light, societies were more concerned with

21336-435: The ten-day "weeks" of their civil calendar. (12 sets of alternate "triangle decans" were used for the 5 epagomenal days between years.) Each night, the rising of eleven of these decans were noted, separating the night into 12 divisions whose middle terms would have lasted about 40   minutes each. (Another seven stars were noted by the Egyptians during the twilight and predawn periods, although they were not important for

21504-492: The term Hellenistic to refer to and define the period when Greek culture spread in the non-Greek world after Alexander's conquest. Following Droysen, Hellenistic and related terms, e.g. Hellenism , have been widely used in various contexts; a notable such use is in Culture and Anarchy by Matthew Arnold , where Hellenism is used in contrast with Hebraism . The major issue with the term Hellenistic lies in its convenience, as

21672-478: The time from sunset to sunrise . Imperial China continued to use ke and geng but also began to divide the day into 12 "double hours" ( t 時 , s 时 , oc * də , p shí , lit. "time[s]") named after the earthly branches and sometimes also known by the name of the corresponding animal of the Chinese zodiac . The first shi originally ran from 11   pm to 1   am but

21840-594: The times of day when commuting slows down due to congestion or alcoholic drinks being available at discounted prices. The hour record for the greatest distance travelled by a cyclist within the span of an hour is one of cycling 's greatest honours. Many different ways of counting the hours have been used. Because sunrise, sunset, and, to a lesser extent, noon, are the conspicuous points in the day, starting to count at these times was, for most people in most early societies, much easier than starting at midnight. However, with accurate clocks and modern astronomical equipment (and

22008-431: The title of king. Athens later allied itself to Ptolemaic Egypt to throw off Macedonian rule, eventually setting up a religious cult for the Ptolemaic kings and naming one of the city's phyles in honour of Ptolemy for his aid against Macedon. In spite of the Ptolemaic monies and fleets backing their endeavors, Athens and Sparta were defeated by Antigonus II during the Chremonidean War (267–261 BC). Athens

22176-507: The traditional system of noting hours is the six-hour clock . This reckons each of a day's 24 hours apart from noon as part of a fourth of the day. The first hour of the first half of daytime was 7 am; 1 pm the first hour of the latter half of daytime; 7 pm the first hour of the first half of nighttime; and 1 am the first hour of the latter half of nighttime. This system existed in the Ayutthaya Kingdom , deriving its current phrasing from

22344-587: The tripartite territorial division of the Hellenistic age was in place, with the main Hellenistic powers being Macedon under Demetrius's son Antigonus II Gonatas , the Ptolemaic kingdom under Ptolemy 's son Ptolemy II and the Seleucid empire under Seleucus' son Antiochus I Soter . Epirus was a northwestern Greek kingdom in the western Balkans ruled by the Molossian Aeacidae dynasty. Epirus

22512-411: The unit metre and time has the unit second, and speed has the derived unit metre per second. Density, or mass per unit volume, has the unit kilogram per cubic metre. A characteristic feature of metric systems is their reliance upon multiples of 10. For example, the base unit of length is the metre, and distances much longer or much shorter than 1 metre are measured in units that are powers of 10 times

22680-450: The unit. Thus the kilogram and kilometre are a thousand grams and metres respectively, and a milligram and millimetre are one thousandth of a gram and metre respectively. These relations can be written symbolically as: The decimalised system is based on the metre , which had been introduced in France in the 1790s . The historical development of these systems culminated in

22848-536: The war against the Spartan king Cleomenes III , and occupied Sparta . Philip V , who came to power when Doson died in 221 BC, was the last Macedonian ruler with both the talent and the opportunity to unite Greece and preserve its independence against the "cloud rising in the west": the ever-increasing power of Rome. He was known as "the darling of Hellas". Under his auspices the Peace of Naupactus (217 BC) brought

23016-620: The world. The French Revolution (1789–99) enabled France to reform its many outdated systems of various local weights and measures. In 1790, Charles Maurice de Talleyrand-Périgord proposed a new system based on natural units to the French National Assembly , aiming for global adoption. With the United Kingdom not responding to a request to collaborate in the development of the system, the French Academy of Sciences established

23184-424: The year. During the New Kingdom , another system of decans was used, made up of 24 stars over the course of the year and 12 within any one night. 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 sundials failed to note time were observed as the first and last hours. The Egyptian hours were closely connected both with

23352-442: Was a borrowing of Old French ure , a variant of ore , which derived from Latin hōra and Greek hṓrā ( ὥρα ). Like Old English tīd and stund , hṓrā was originally a vaguer word for any span of time, including seasons and years . Its Proto-Indo-European root has been reconstructed as *yeh₁- ("year, summer "), making hour distantly cognate with year . The time of day

23520-548: Was a union of Thracian tribes under the kings of the powerful Odrysian tribe. Various parts of Thrace were under Macedonian rule under Philip II of Macedon , Alexander the Great , Lysimachus , Ptolemy II , and Philip V but were also often ruled by their own kings. The Thracians and Agrianes were widely used by Alexander as peltasts and light cavalry , forming about one-fifth of his army. The Diadochi also used Thracian mercenaries in their armies and they were also used as colonists. The Odrysians used Greek as

23688-457: Was able to drive out the Macedonians from the Peloponnese and free Corinth, which duly joined the league. One of the few city states who managed to maintain full independence from the control of any Hellenistic kingdom was Rhodes . With a skilled navy to protect its trade fleets from pirates and an ideal strategic position covering the routes from the east into the Aegean, Rhodes prospered during

23856-422: Was accompanied by the rise of Sirius before the sunrise, and the appearance of 12 constellations across the night sky, to which the Egyptians assigned some significance. Influenced by this, the Egyptians divided the night into 12 equal intervals. These were seasonal hours , shorter in the summer than in the winter. Subsequently, the day was divided into intervals as well, which eventually became more important than

24024-435: Was added in 1999. The base units used in a measurement system must be realisable . Each of the definitions of the base units in the SI is accompanied by a defined mise en pratique [practical realisation] that describes in detail at least one way in which the base unit can be measured. Where possible, definitions of the base units were developed so that any laboratory equipped with proper instruments would be able to realise

24192-483: Was also a center of education, where Celts went to learn Greek. A staunch ally of Rome, Massalia retained its independence until it sided with Pompey in 49 BC and was then taken by Caesar's forces . The city of Emporion (modern Empúries ), originally founded by Archaic-period settlers from Phocaea and Massalia in the 6th century BC near the village of Sant Martí d'Empúries (located on an offshore island that forms part of L'Escala , Catalonia , Spain ),

24360-474: Was an ally of Macedon during the reigns of Philip II and Alexander. In 281 Pyrrhus (nicknamed "the eagle", aetos ) invaded southern Italy to aid the city state of Tarentum . Pyrrhus defeated the Romans in the Battle of Heraclea and at the Battle of Asculum . Though victorious, he was forced to retreat due to heavy losses, hence the term " Pyrrhic victory ". Pyrrhus then turned south and invaded Sicily but

24528-528: Was assassinated by Ptolemy Ceraunus ("the thunderbolt"), who had taken refuge at the Seleucid court and then had himself acclaimed as king of Macedon. Ptolemy was killed when Macedon was invaded by Gauls in 279 BC —his head stuck on a spear—and the country fell into anarchy. Antigonus II Gonatas invaded Thrace in the summer of 277 and defeated a large force of 18,000 Gauls. He was quickly hailed as king of Macedon and went on to rule for 35 years. At this point

24696-628: Was assassinated. Succeeding his father, Alexander took over the Persian war himself. During a decade of campaigning, Alexander conquered the whole Persian Empire , overthrew the Persian king Darius III . The conquered lands included Asia Minor , Assyria , the Levant , Egypt , Mesopotamia , Media , Persia , and parts of modern-day Afghanistan , Pakistan , and the steppes of central Asia. The years of constant campaigning had taken their toll, however, and Alexander died in 323 BC. After his death,

24864-507: Was crushed at the Battle of Sellasia (222 BC) by the Achaean league and Macedon, who restored the power of the ephors . Other city states formed federated states in self-defense, such as the Aetolian League ( est. 370 BC), the Achaean League ( est. 280 BC), the Boeotian league , the "Northern League" ( Byzantium , Chalcedon , Heraclea Pontica and Tium ) and

25032-462: Was defeated and captured by the Romans in the Third Macedonian War (171–168 BC). During the Hellenistic period, the importance of Greece proper within the Greek-speaking world declined sharply. The great centers of Hellenistic culture were Alexandria and Antioch , capitals of Ptolemaic Egypt and Seleucid Syria respectively. The conquests of Alexander greatly widened the horizons of

25200-617: Was defeated in 288 BC when Lysimachus of Thrace and Pyrrhus of Epirus invaded Macedon on two fronts, and quickly carved up the kingdom for themselves. Demetrius fled to central Greece with his mercenaries and began to build support there and in the northern Peloponnese. He once again laid siege to Athens after they turned on him, but then struck a treaty with the Athenians and Ptolemy, which allowed him to cross over to Asia Minor and wage war on Lysimachus' holdings in Ionia , leaving his son Antigonus Gonatas in Greece. After initial successes, he

25368-581: Was divided into four watches or vigils of three hours each, the first, the second, the third, and the fourth vigil. The Horae were originally personifications of seasonal aspects of nature, not of the time of day. The list of 12 Horae representing the 12 hours of the day is recorded only in Late Antiquity , by Nonnus . The first and twelfth of the Horae were added to the original set of ten: Medieval astronomers such as al-Biruni and Sacrobosco , divided

25536-449: Was forced to surrender to Seleucus in 285 BC and later died in captivity. Lysimachus, who had seized Macedon and Thessaly for himself, was forced into war when Seleucus invaded his territories in Asia Minor and was defeated and killed in 281 BC at the Battle of Corupedium , near Sardis . Seleucus then attempted to conquer Lysimachus' European territories in Thrace and Macedon, but he

25704-520: Was influenced by Greek designs, and Greek letters can be found on various Celtic coins, especially those of Southern France . Traders from Massalia ventured inland deep into France on the Rivers Durance and Rhône , and established overland trade routes deep into Gaul , and to Switzerland and Burgundy . The Hellenistic period saw the Greek alphabet spread into southern Gaul from Massalia (3rd and 2nd centuries BC) and according to Strabo , Massalia

25872-719: Was inhabited by various Illyrian tribes and kingdoms such as the kingdom of the Dalmatae and of the Ardiaei , who often engaged in piracy under Queen Teuta (reigned 231–227 BC). Further inland was the Illyrian Paeonian Kingdom and the tribe of the Agrianes . Illyrians on the coast of the Adriatic were under the effects and influence of Hellenisation and some tribes adopted Greek, becoming bilingual due to their proximity to

26040-426: Was joined by Eumenes) and was supported by Antigonus, Lysimachus and Ptolemy. In 317 BC, Cassander invaded Macedonia, attaining control of Macedon, sentencing Olympias to death and capturing the boy king Alexander IV , and his mother. In Asia, Eumenes was betrayed by his own men after years of campaign and was given up to Antigonus who had him executed. The third war of the Diadochi broke out because of

26208-511: Was measured with sundials and water clocks . Into the Eastern Han , the Chinese measured their day schematically, adding the 20- ke difference between the solstices evenly throughout the year, one every nine days. During the night, time was more commonly reckoned during the night by the "watches" ( Chinese : 更 , oc * kæŋ , p gēng ) of the guard, which were reckoned as a fifth of

26376-468: Was pre-eminent but not all-powerful. Spartan hegemony was succeeded by a Theban hegemony after the Battle of Leuctra (371 BC), but after the Battle of Mantinea (362 BC) , all of Greece was so weakened that no one state could claim pre-eminence. It was against this backdrop that the ascendancy of Macedon began, under king Philip II . Macedon was located at the periphery of the Greek world, and although its royal family claimed Greek descent,

26544-539: Was reckoned as starting at midnight by the time of the History of Song , compiled during the early Yuan . These apparently began to be used during the Eastern Han that preceded the Three Kingdoms era, but the sections that would have covered them are missing from their official histories; they first appear in official use in the Tang -era Book of Sui . Variations of all these units were subsequently adopted by Japan and

26712-511: Was reestablished in the 5th century BC with a new city ( neapolis ) on the Iberian mainland . Emporion contained a mixed population of Greek colonists and Iberian natives, and although Livy and Strabo assert that they lived in different quarters , these two groups were eventually integrated. The city became a dominant trading hub and center of Hellenistic civilization in Iberia, eventually siding with

26880-535: Was remedied at the 1893 International Electrical Congress held in Chicago by defining the "international" ampere and ohm using definitions based on the metre , kilogram and second , in the International System of Electrical and Magnetic Units . During the same period in which the CGS system was being extended to include electromagnetism, other systems were developed, distinguished by their choice of coherent base unit, including

27048-413: Was suspended six months later by the same 1795 legislation that first established the metric system. In spite of this, a few localities continued to use decimal time for six years for civil status records, until 1800, after Napoleon's Coup of 18 Brumaire. The metric system bases its measurements of time upon the second , defined since 1952 in terms of the Earth's rotation in AD   1900. Its hours are

27216-457: Was the first to adopt this custom), having themselves portrayed on public monuments in Egyptian style and dress, and participating in Egyptian religious life. The Ptolemaic ruler cult portrayed the Ptolemies as gods, and temples to the Ptolemies were erected throughout the kingdom. Ptolemy I even created a new god, Serapis , who was a combination of two Egyptian gods: Apis and Osiris, with attributes of Greek gods . Ptolemaic administration was, like

27384-544: Was then occupied by Macedonian troops, and run by Macedonian officials. Sparta remained independent, but it was no longer the leading military power in the Peloponnese . The Spartan king Cleomenes III (235–222 BC) staged a military coup against the conservative ephors and pushed through radical social and land reforms in order to increase the size of the shrinking Spartan citizenry able to provide military service and restore Spartan power. Sparta's bid for supremacy

27552-404: Was unsuccessful and returned to Italy. After the Battle of Beneventum (275 BC) Pyrrhus lost all his Italian holdings and left for Epirus. Pyrrhus then went to war with Macedonia in 275 BC, deposing Antigonus II Gonatas and briefly ruling over Macedonia and Thessaly until 272. Afterwards, he invaded southern Greece and was killed in battle against Argos in 272 BC. After

27720-520: Was used both in France and in the Soviet Union . Gravitational metric systems use the kilogram-force (kilopond) as a base unit of force, with mass measured in a unit known as the hyl , Technische Masseneinheit (TME), mug or metric slug . Although the CGPM passed a resolution in 1901 defining the standard value of acceleration due to gravity to be 980.665 cm/s , gravitational units are not part of

27888-475: Was used to indicate an hour. The time was measured based on the length of the shadow at day time. A hora translated to 2.5 pe . There are 60 pe per day, 60 minutes per pe and 60 kshana (snap of a finger or instant) per minute. Pe was measured with a bowl with a hole placed in still water. Time taken for this graduated bowl was one pe . Kings usually had an officer in charge of this clock. In so-called " Italian time", "Italian hours", or "old Czech time",

28056-510: Was used until a new definition was introduced in May 2019 . Replicas made in 1879 at the time of the artefact's fabrication and distributed to signatories of the Metre Convention serve as de facto standards of mass in those countries. Additional replicas have been fabricated since as additional countries have joined the convention. The replicas were subject to periodic validation by comparison to

28224-457: Was variously divided into 30 muhūrta-s of 48 minutes each or 60 dandas or nadī-s of 24 minutes each. The solar day was later similarly divided into 60 ghaṭikás of about the same duration, each divided in turn into 60 vinadis . The Sinhalese followed a similar system but called their sixtieth of a day a peya . Metric symbol The metric system is a decimal -based system of measurement . The current international standard for

#957042