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Digit (unit)
The digit or finger is an ancient and obsolete non- SI unit of measurement of length. It was originally based on the breadth of a human finger. It was a fundamental unit of length in the Ancient Egyptian, Mesopotamian, Hebrew, Ancient Greek and Roman systems of measurement. In astronomy a digit is one twelfth of the diameter of the sun or the moon. History Ancient Egypt The digit, also called a finger or fingerbreadth, is a unit of measurement originally based on the breadth of a human finger. In Ancient Egypt it was the basic unit of subdivision of the cubit. On surviving Ancient Egyptian cubit-rods, the royal cubit is divided into seven palms of four digits or fingers each. The royal cubit measured approximately 525 mm, so the length of the ancient Egyptian digit was about 19 mm. Mesopotamia In the classical Akkadian Empire system instituted in about 2250 BC during the reign of Naram-Sin, the finger was one-thirtieth of a cubit length. The cubit was equiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1 E-2 M
The following are examples of order of magnitude, orders of magnitude for different lengths. Overview Detailed list To help compare different orders of magnitude, the following list describes various lengths between 1.6 \times 10^ metres and 10^metres. Subatomic scale Atomic to cellular scale Cellular to human scale Human to astronomical scale Astronomical scale 1 quectometre and less The ' (SI symbol: ') is a Units of measurement, unit of length in the metric system equal to . To help compare different orders of magnitude, this section lists lengths shorter than 10−30 metre, m (1 qm). *1.6 × 10−5 quectometres (1.6 × 10−35 metres) – the Planck length (Measures of distance shorter than this do not make physical sense, according to current theories of physics.) *1 qm – 1 quectometre, the smallest named subdivision of the metre in the SI base unit of length, one nonillionth of a metre. 1 rontometre The ' (SI symbol: ') is a Units of meas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dioptra
A dioptra (sometimes also named dioptre or diopter, from ) is a classical astronomical and surveying instrument, dating from the 3rd century BC. The dioptra was a sighting tube or, alternatively, a rod with a sight at both ends, attached to a stand. If fitted with protractors, it could be used to measure angles. Use Greek astronomers used the dioptra to measure the positions of stars; both Euclid and Geminus refer to the dioptra in their astronomical works. It continued in use as an effective surveying tool. Adapted to surveying, the dioptra is similar to the theodolite, or surveyor's transit, which dates to the sixteenth century. It is a more accurate version of the groma. There is some speculation that it may have been used to build the Eupalinian aqueduct. Called "one of the greatest engineering achievements of ancient times," it is a tunnel long, excavated through a mountain on the Greek island of Samos during the reign of Polycrates in the sixth century B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sosigenes Of Alexandria
Sosigenes () (fl. 1st century BC) was an Ancient Greek astronomer. According to Pliny the Elder's ''Natural History'' 18.210–212, Julius Caesar consulted him while he was designing the Julian calendar. Biography Little is known about him apart from Pliny's ''Natural History''. Sosigenes appears in Book 18, 210-212: Sosigenes is credited with work on the orbit of Mercury, which is described by Pliny in book 2, ''Natural History'': The introduction of the Julian year occurred in 46 BC. This particular year lasted 445 days in Rome to correct the erroneous old Roman calendar, and is thus considered "the longest year in history". Cultural depiction Since the 18th century, the classicists have added to the name of Sosigenes, to distinguish it from others, the origin: "of Alexandria". However, no ancient source calls him that, or indicates that he was an Alexandrian. The misattribution may be from the fusion of two pieces of news about the reform of the Roman calendar at t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ptolemy
Claudius Ptolemy (; , ; ; – 160s/170s AD) was a Greco-Roman mathematician, astronomer, astrologer, geographer, and music theorist who wrote about a dozen scientific treatises, three of which were important to later Byzantine science, Byzantine, Islamic science, Islamic, and Science in the Renaissance, Western European science. The first was his astronomical treatise now known as the ''Almagest'', originally entitled ' (, ', ). The second is the ''Geography (Ptolemy), Geography'', which is a thorough discussion on maps and the geographic knowledge of the Greco-Roman world. The third is the astrological treatise in which he attempted to adapt horoscopic astrology to the Aristotelian physics, Aristotelian natural philosophy of his day. This is sometimes known as the ' (, 'On the Effects') but more commonly known as the ' (from the Koine Greek meaning 'four books'; ). The Catholic Church promoted his work, which included the only mathematically sound geocentric model of the Sola ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plutarch
Plutarch (; , ''Ploútarchos'', ; – 120s) was a Greek Middle Platonist philosopher, historian, biographer, essayist, and priest at the Temple of Apollo (Delphi), Temple of Apollo in Delphi. He is known primarily for his ''Parallel Lives'', a series of biographies of illustrious Greeks and Romans, and ''Moralia'', a collection of essays and speeches. Upon becoming a Roman citizen, he was possibly named Lucius Mestrius Plutarchus (). Family Plutarch was born to a prominent family in the small town of Chaeronea, about east of Delphi, in the Greek region of Boeotia. His family was long established in the town; his father was named Autobulus and his grandfather was named Lamprias. His brothers, Timon and Lamprias, are frequently mentioned in his essays and dialogues, which speak of Timon in particular in the most affectionate terms. Studies and life Plutarch studied mathematics and philosophy in Athens under Ammonius of Athens, Ammonius from AD 66 to 67. He attended th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moralia
The ''Moralia'' (Latin for "Morals", "Customs" or "Mores"; , ''Ethiká'') is a set of essays ascribed to the 1st-century scholar Plutarch of Chaeronea. The eclectic collection contains 78 essays and transcribed speeches. They provide insights into Roman and Greek life, but they also include timeless observations. Many generations of Europeans have read or imitated them, including Michel de Montaigne, Renaissance Humanists and Enlightenment philosophers. Contents General structure The ''Moralia'' include ''On the Fortune or the Virtue of Alexander the Great'', an important adjunct to Plutarch's ''Life'' of the great general; ''On the Worship of Isis and Osiris'', a crucial source of information on Egyptian religious rites; and '' On the Malice of Herodotus'' (which may, like the orations on Alexander's accomplishments, have been a rhetorical exercise), in which Plutarch criticizes what he sees as systematic bias in the '' Histories'' of Herodotus; along with more philosop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ell (unit)
An ell (from Proto-Germanic *''alinō'', cognate with Latin ''ulna'') is a northwestern European unit of measurement, originally understood as a cubit (the combined length of the forearm and extended hand). The word literally means "arm", and survives in the modern English word "elbow" (arm-bend). Later usage through the 19th century refers to several longer units, some of which are thought to derive from a "double ell". An ell-wand or ellwand was a rod of length one ell used for official measurement. Edward I of England required that every town have one. In Scotland, the Belt of Orion was called "the King's Ellwand". An iron ellwand is preserved in the entrance to Stånga Church on the Swedish island of Gotland, indicating the role that rural churches had in disseminating uniform measures. Several national forms existed, with different lengths, including the Scottish ell , the Flemish ell l, the French ell une,Brayshaw, Tom S., ed. ''Brayshaw's Mathematical Desk Co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Span (length)
A span is the distance measured by a human hand, from the tip of the thumb to the tip of the little finger. In ancient times, a span was considered to be half a cubit. Sometimes the distinction is made between the great span or full span (thumb to little finger) and little span or short span (thumb to index finger, or index finger to little finger). History Ancient Greek texts show that the span was used as a fixed measure in ancient Greece since at least archaic period. The word ''spithame'' (Greek: "σπιθαμή"), "span", is attested in the work of Herodotus in the 5th century BC; however, the span was used in Greece long before that, since the word ''trispithamos'' (Greek: "τρισπίθαμος"), "three spans long", occurs as early as the 8th century BC in Hesiod. Hesiod, ''Works and Days'', 426, oPerseus Digital Library/ref> Size of the span English usage ; 1 span := 9 inches := 22.86 cm Chinese usage In China and Chinese cultured countries, a span (一拃) refers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shaftment
The shaftment is an obsolete unit of length defined since the 12th century as 6 inches, which nowadays is exactly . A shaftment was traditionally the width of the fist and outstretched thumb. The lengths of poles, staves, etc. can be easily measured by grasping the bottom of the staff with thumb extended and repeating such hand over hand grips along the length of the staff. History It occurs in Anglo-Saxon written records as early as 910 and in English as late as 1474. After the modern foot came into use in the twelfth century, the shaftment was reinterpreted as exactly foot or . Spelling and etymology Other spellings include ''schaftmond'' and ''scaeftemunde'', and ''shathmont''. It is derived from Old English , in turn from ('shaft') and Old English , from the Proto-Germanic , in turn from ('hand'). Two shaftments make a . This unit has mostly fallen out of use, as have others based on the human arm: digit ( shaftment), finger ( shaftment), palm ( shaftment) hand ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hand (unit)
The hand is a non-SI unit of measurement of length standardized to . It is used to measure the height of horses in many English-speaking countries, including Australia, Canada, Republic of Ireland, Ireland, the United Kingdom, and the United States. It was originally based on the breadth of a human hand. The adoption of the Inch#Equivalents, international inch in 1959 allowed for a standardized Imperial and US customary measurement systems#Units of length, imperial form and a Metric system, metric conversion. It may be abbreviated to "h" or "hh". Although measurements between whole hands are usually expressed in what appears to be decimal format, the subdivision of the hand is not decimal but is in radix, base 4, so subdivisions after the radix point are in quarters of a hand, which are inches. Thus, 62 inches is fifteen and a half hands, or 15.2 hh (normally said as "fifteen-two", or occasionally in full as "fifteen hands two inches"). Terminology "Hands" may be abbrevia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
