Misplaced Pages

#457542

122-437: The astrolabe, which is a precursor to the sextant , is effective for determining latitude on land or calm seas. Although it is less reliable on the heaving deck of a ship in rough seas, the mariner's astrolabe was developed to solve that problem. The 10th century astronomer ʿAbd al-Raḥmān al-Ṣūfī wrote a massive text of 386 chapters on the astrolabe, which reportedly described more than 1,000 applications for

244-417: A church spire, which can then be used to find the distance off or out to sea (provided the distance between the two landmarks is known). Used vertically, a measurement of the angle between the lantern of a lighthouse of known height and the sea level at its base can also be used for distance off. Due to the sensitivity of the instrument it is easy to knock the mirrors out of adjustment. For this reason

366-441: A circle (45°), 1 ⁄ 5 of a circle (72°) and 1 ⁄ 4 of a circle (90°), respectively. All of these instruments may be termed "sextants". Attached to the frame are the "horizon mirror", an index arm which moves the index mirror , a sighting telescope, Sun shades, a graduated scale and a micrometer drum gauge for accurate measurements. The scale must be graduated so that the marked degree divisions register twice

488-426: A complicated and extensive syllabary. A considerable amount of Babylonian literature was translated from Sumerian originals, and the language of religion and law long continued to be the old agglutinative language of Sumer. Vocabularies, grammars, and interlinear translations were compiled for the use of students, as well as commentaries on the older texts and explanations of obscure words and phrases. The characters of

610-433: A detailed treatise on the astrolabe. The invention of the plane astrolabe is sometimes wrongly attributed to Theon's daughter Hypatia (born c.  350–370 ; died 415 CE ), but it's known to have been used much earlier. The misattribution comes from a misinterpretation of a statement in a letter written by Hypatia's pupil Synesius ( c.  373–414 ), which mentions that Hypatia had taught him how to construct

732-471: A disk with a wide, raised rim, called the mater (mother), which is deep enough to hold one or more flat plates called tympans , or climates . A tympan is made for a specific latitude and is engraved with a stereographic projection of circles denoting azimuth and altitude and representing the portion of the celestial sphere above the local horizon. The rim of the mater is typically graduated into hours of time , degrees of arc , or both. Above

854-459: A flash of the Sun's rays are seen in the telescope. Fine adjustments are then made as above. This method is less likely to be successful for sighting stars and planets. Star and planet sights are normally taken during nautical twilight at dawn or dusk , while both the heavenly bodies and the sea horizon are visible. There is no need to use shades or to distinguish the lower limb as the body appears as

976-612: A language of the Zagros possibly related to the Hurro-Urartuan language family , is attested in personal names, rivers and mountains and in various crafts. Akkadian came to be the dominant language during the Akkadian Empire and the Assyrian empires, but Sumerian was retained for administrative, religious, literary and scientific purposes. Different varieties of Akkadian were used until

1098-404: A mere point in the telescope. The Moon can be sighted, but it appears to move very fast, appears to have different sizes at different times, and sometimes only the lower or upper limb can be distinguished due to its phase . After a sight is taken, it is reduced to a position by looking at several mathematical procedures. The simplest sight reduction is to draw the equal-altitude circle of

1220-442: A mirror larger than 2.5 cm (one inch). In large part, this is because precision flat mirrors have grown less expensive to manufacture and to silver . An artificial horizon is useful when the horizon is invisible, as occurs in fog, on moonless nights, in a calm, when sighting through a window or on land surrounded by trees or buildings. There are two common designs of artificial horizon. An artificial horizon can consist simply of

1342-482: A patient could not be cured physically, the Babylonian physicians often relied on exorcism to cleanse the patient from any curses . Esagil-kin-apli's Diagnostic Handbook was based on a logical set of axioms and assumptions, including the modern view that through the examination and inspection of the symptoms of a patient, it is possible to determine the patient's disease , its aetiology, its future development, and

SECTION 10

#1732844360458

1464-517: A plane astrolabe, but does not say that she invented it. Lewis argues that Ptolemy used an astrolabe to make the astronomical observations recorded in the Tetrabiblos . However, Emilie Savage-Smith notes In chapter 5.1 of the Almagest , Ptolemy describes the construction of an armillary sphere , and it is usually assumed that this was the instrument he used. Astrolabes continued to be used in

1586-462: A pool of water shielded from the wind, allowing the user to measure the distance between the body and its reflection, and divide by two. Another design allows the mounting of a fluid-filled tube with bubble directly to the sextant. Most sextants also have filters for use when viewing the Sun and reducing the effects of haze. The filters usually consist of a series of progressively darker glasses that can be used singly or in combination to reduce haze and

1708-549: A precursor to the Socratic method . The Ionian philosopher Thales was influenced by Babylonian cosmological ideas. Ancient Mesopotamians had ceremonies each month. The theme of the rituals and festivals for each month was determined by at least six important factors: Some songs were written for the gods but many were written to describe important events. Although music and songs amused kings , they were also enjoyed by ordinary people who liked to sing and dance in their homes or in

1830-456: A radius connects from the center of the astrolabe to the optical axis which is parallel with another arm also called a radius. The other radius contains graduations of altitude and distance measurements. A shadow square also appears on the back of some astrolabes, developed by Muslim astrologists in the 9th Century, whereas devices of the Ancient Greek tradition featured only altitude scales on

1952-730: A recent hypothesis, the Archimedes' screw may have been used by Sennacherib, King of Assyria, for the water systems at the Hanging Gardens of Babylon and Nineveh in the 7th century BC, although mainstream scholarship holds it to be a Greek invention of later times. Later, during the Parthian or Sasanian periods, the Baghdad Battery , which may have been the world's first battery, was created in Mesopotamia. The Ancient Mesopotamian religion

2074-550: A sacred, ceremonial, literary, and scientific language in Mesopotamia until the 1st century AD. Libraries were extant in towns and temples during the Babylonian Empire. An old Sumerian proverb averred that "he who would excel in the school of the scribes must rise with the dawn." Women as well as men learned to read and write, and for the Semitic Babylonians, this involved knowledge of the extinct Sumerian language, and

2196-410: A sextant is intensely personal to each navigator, and they will choose whichever model has the features which suit them best. Aircraft sextants are now out of production, but had special features. Most had artificial horizons to permit taking a sight through a flush overhead window. Some also had mechanical averagers to make hundreds of measurements per sight for compensation of random accelerations in

2318-524: A sextant is used on a moving ship, the image of both horizon and celestial object will move around in the field of view. However, the relative position of the two images will remain steady, and as long as the user can determine when the celestial object touches the horizon, the accuracy of the measurement will remain high compared to the magnitude of the movement. The sextant is not dependent upon electricity (unlike many forms of modern navigation) or any human-controlled signals (such as GPS). For these reasons it

2440-544: A sextant should be checked frequently for errors and adjusted accordingly. There are four errors that can be adjusted by the navigator, and they should be removed in the following order. Mesopotamian Mesopotamia is a historical region of West Asia situated within the Tigris–Euphrates river system , in the northern part of the Fertile Crescent . Today, Mesopotamia is known as present-day Iraq . In

2562-545: A star map rotating behind a fixed rete, similar to that of an astrolabe. Many astronomical clocks use an astrolabe-style display, such as the famous clock at Prague , adopting a stereographic projection (see below) of the ecliptic plane. In recent times, astrolabe watches have become popular. For example, Swiss watchmaker Ludwig Oechslin designed and built an astrolabe wristwatch in conjunction with Ulysse Nardin in 1985. Dutch watchmaker Christaan van der Klauuw also manufactures astrolabe watches today. An astrolabe consists of

SECTION 20

#1732844360458

2684-415: A table of Pythagorean triples and represents some of the most advanced mathematics prior to Greek mathematics. From Sumerian times, temple priesthoods had attempted to associate current events with certain positions of the planets and stars. This continued to Assyrian times, when Limmu lists were created as a year by year association of events with planetary positions, which, when they have survived to

2806-510: A vast mountainous region. Overland routes in Mesopotamia usually follow the Euphrates because the banks of the Tigris are frequently steep and difficult. The climate of the region is semi-arid with a vast desert expanse in the north which gives way to a 15,000-square-kilometre (5,800 sq mi) region of marshes, lagoons, mudflats, and reed banks in the south. In the extreme south, the Euphrates and

2928-580: Is an-ki , which refers to the god An and the goddess Ki . Their son was Enlil, the air god. They believed that Enlil was the most powerful god. He was the chief god of the pantheon . The numerous civilizations of the area influenced the Abrahamic religions , especially the Hebrew Bible . Its cultural values and literary influence are especially evident in the Book of Genesis . Giorgio Buccellati believes that

3050-408: Is a doubly reflecting navigation instrument that measures the angular distance between two visible objects. The primary use of a sextant is to measure the angle between an astronomical object and the horizon for the purposes of celestial navigation . The estimation of this angle, the altitude, is known as sighting or shooting the object, or taking a sight . The angle, and the time when it

3172-414: Is a composite product, although it is probable that some of the stories are artificially attached to the central figure. Mesopotamian mathematics and science was based on a sexagesimal (base 60) numeral system . This is the source of the 60-minute hour, the 24-hour day, and the 360- degree circle. The Sumerian calendar was lunisolar, with three seven-day weeks of a lunar month. This form of mathematics

3294-464: Is accurate to about six decimal digits, and is the closest possible three-place sexagesimal representation of √ 2 : The Babylonians were not interested in exact solutions, but rather approximations, and so they would commonly use linear interpolation to approximate intermediate values. One of the most famous tablets is the Plimpton 322 tablet , created around 1900–1600 BC, which gives

3416-551: Is also a folk etymology of the word as "lines of lab", where "Lab" refers to a certain son of Idris ( Enoch ). This etymology is mentioned by a 10th century scientist named al-Qummi but rejected by al-Khwarizmi . An astrolabe is essentially a plane (two-dimensional) version of an armillary sphere , which had already been invented in the Hellenistic period and probably been used by Hipparchus to produce his star catalogue. Theon of Alexandria ( c.  335–405 ) wrote

3538-580: Is compatible with ergodic axioms. Logic was employed to some extent in Babylonian astronomy and medicine. Babylonian thought had a considerable influence on early Ancient Greek and Hellenistic philosophy . In particular, the Babylonian text Dialogue of Pessimism contains similarities to the agonistic thought of the Sophists , the Heraclitean doctrine of dialectic , and the dialogs of Plato , as well as

3660-498: Is considered to be an eminently practical back-up navigation tool for ships. The frame of a sextant is in the shape of a sector which is approximately 1 ⁄ 6 of a circle (60°), hence its name ( sextāns, sextantis is the Latin word for "one sixth"). Both smaller and larger instruments are (or were) in use: the octant , quintant (or pentant ) and the (doubly reflecting) quadrant span sectors of approximately 1 ⁄ 8 of

3782-475: Is dated AH 315 (927–928 CE ). In the Islamic world, astrolabes were used to find the times of sunrise and the rising of fixed stars, to help schedule morning prayers ( salat ). In the 10th century, al-Sufi first described over 1,000 different uses of an astrolabe, in areas as diverse as astronomy , astrology , navigation , surveying , timekeeping, prayer, Salat , Qibla , etc. The spherical astrolabe

Astrolabe - Misplaced Pages Continue

3904-405: Is lower-expansion than aluminium, but aluminium sextants are lighter and less tiring to use. Some say they are more accurate because one's hand trembles less. Solid brass frame sextants are less susceptible to wobbling in high winds or when the vessel is working in heavy seas, but as noted are substantially heavier. Sextants with aluminum frames and brass arcs have also been manufactured. Essentially,

4026-400: Is that both the horizon and celestial object are bright and as clear as possible. This is superior at night and in haze, when the horizon and/or a star being sighted can be difficult to see. However, one has to sweep the celestial object to ensure that the lowest limb of the celestial object touches the horizon. Whole-horizon sextants use a half-silvered horizon mirror to provide a full view of

4148-506: Is the Destombes astrolabe made from brass in the eleventh century in Portugal. Metal astrolabes avoided the warping that large wooden ones were prone to, allowing the construction of larger and therefore more accurate instruments. Metal astrolabes were heavier than wooden instruments of the same size, making it difficult to use them in navigation. Herman Contractus of Reichenau Abbey , examined

4270-403: Is the component that will enable the precise determination of a star's position at a specific time of day and year . Therefore, it should project: On the right side of the image above: When projecting onto the celestial equatorial plane, three concentric circles correspond to the celestial sphere's three circles of latitude (left side of the image). The largest of these, the projection on

4392-421: Is uncertain. The Babylonian development of methods for predicting the motions of the planets is considered to be a major episode in the history of astronomy . The only Greek-Babylonian astronomer known to have supported a heliocentric model of planetary motion was Seleucus of Seleucia (b. 190 BC). Seleucus is known from the writings of Plutarch . He supported Aristarchus of Samos' heliocentric theory where

4514-610: The Byzantine Empire . Christian philosopher John Philoponus wrote a treatise ( c.  550 ) on the astrolabe in Greek, which is the earliest extant treatise on the instrument. Mesopotamian bishop Severus Sebokht also wrote a treatise on the astrolabe in the Syriac language during the mid-7th century. Sebokht refers to the astrolabe as being made of brass in the introduction of his treatise, indicating that metal astrolabes were known in

4636-455: The Davis quadrant , the sextant allows celestial objects to be measured relative to the horizon, rather than relative to the instrument. This allows excellent precision. Also, unlike the backstaff, the sextant allows direct observations of stars. This permits the use of the sextant at night when a backstaff is difficult to use. For solar observations, filters allow direct observation of the Sun. Since

4758-663: The Earth rotated around its own axis which in turn revolved around the Sun . According to Plutarch , Seleucus even proved the heliocentric system, but it is not known what arguments he used, except that he correctly theorized on tides as a result of the Moon's attraction. Babylonian astronomy served as the basis for much of Greek , classical Indian , Sassanian, Byzantine , Syrian , medieval Islamic , Central Asian , and Western European astronomy. The oldest Babylonian texts on medicine date back to

4880-599: The Jazira , is the area between the Euphrates and the Tigris from their sources down to Baghdad . Lower Mesopotamia is the area from Baghdad to the Persian Gulf and includes Kuwait and parts of western Iran. In modern academic usage, the term Mesopotamia often also has a chronological connotation. It is usually used to designate the area until the Muslim conquests , with names like Syria , Jazira , and Iraq being used to describe

5002-688: The Old Babylonian period in the first half of the 2nd millennium BC . The most extensive Babylonian medical text, however, is the Diagnostic Handbook written by the ummânū , or chief scholar, Esagil-kin-apli of Borsippa , during the reign of the Babylonian king Adad-apla-iddina (1069–1046 BC). Along with contemporary Egyptian medicine , the Babylonians introduced the concepts of diagnosis , prognosis , physical examination , enemas , and prescriptions . The Diagnostic Handbook introduced

Astrolabe - Misplaced Pages Continue

5124-607: The Ptolemaic model , and Earth was shown as a blue sphere with circles of geographic coordinates. A complicated line representing the axis of the Earth covered the entire instrument. Mechanical astronomical clocks were initially influenced by the astrolabe; they could be seen in many ways as clockwork astrolabes designed to produce a continual display of the current position of the sun, stars, and planets. For example, Richard of Wallingford 's clock ( c.  1330 ) consisted essentially of

5246-594: The lunar calendar that was informed by the calculations of the astrolabe was of great significance to the religion of Islam, given that it determines the dates of important religious observances such as Ramadan . The Oxford English Dictionary gives the translation "star-taker" for the English word astrolabe and traces it through medieval Latin to the Greek word ἀστρολάβος  : astrolábos , from ἄστρον : astron "star", and λαμβάνειν : lambanein "to take". In

5368-503: The lunar distance between the moon and another celestial object (such as a star or planet) in order to determine Greenwich Mean Time and hence longitude . The principle of the instrument was first implemented around 1731 by John Hadley (1682–1744) and Thomas Godfrey (1704–1749), but it was also found later in the unpublished writings of Isaac Newton (1643–1727). In 1922, it was modified for aeronautical navigation by Portuguese navigator and naval officer Gago Coutinho . Like

5490-438: The marketplaces . Songs were sung to children who passed them on to their children. Thus songs were passed on through many generations as an oral tradition until writing was more universal. These songs provided a means of passing on through the centuries highly important information about historical events. Hunting was popular among Assyrian kings. Boxing and wrestling feature frequently in art, and some form of polo

5612-407: The É , a temple dedicated to the goddess Inanna at Uruk, from a building labeled as Temple C by its excavators. The early logographic system of cuneiform script took many years to master. Thus, only a limited number of individuals were hired as scribes to be trained in its use. It was not until the widespread use of a syllabic script was adopted under Sargon's rule that significant portions of

5734-679: The (two) rivers") comes from the ancient Greek root words μέσος ( mesos , 'middle') and ποταμός ( potamos , 'river') and translates to '(land) between rivers', likely being a calque of the older Aramaic term, with the Aramaic term itself likely being a calque of the Akkadian birit narim . It is used throughout the Greek Septuagint ( c.  250 BC ) to translate the Hebrew and Aramaic equivalent Naharaim . An even earlier Greek usage of

5856-432: The 1st century BC and 3rd century AD, including Adiabene , Osroene , and Hatra . The regional toponym Mesopotamia ( / ˌ m ɛ s ə p ə ˈ t eɪ m i ə / , Ancient Greek : Μεσοποταμία '[land] between rivers'; Arabic : بِلَاد ٱلرَّافِدَيْن Bilād ar-Rāfidayn or بَيْن ٱلنَّهْرَيْن Bayn an-Nahrayn ; Persian : میان‌رودان miyân rudân ; Syriac : ܒܝܬ ܢܗܪ̈ܝܢ Beth Nahrain "(land) between

5978-447: The 40° E meridian, another circle is obtained that passes through both the zenith and nadir projections, so its center is located on the perpendicular bisection of the segment connecting both points. In deed, the projection of the celestial meridian can be considered as a circle with an infinite radius (a straight line) whose center is on this bisection and at an infinite distance from these two points. If successive meridians that divide

6100-532: The 8,000-year-old remains of early farmers found at an ancient graveyard in Germany . They compared the genetic signatures to those of modern populations and found similarities with the DNA of people living in today's Turkey and Iraq . The earliest language written in Mesopotamia was Sumerian , an agglutinative language isolate . Along with Sumerian, Semitic languages were also spoken in early Mesopotamia. Subartuan ,

6222-610: The Christian East well before they were developed in the Islamic world or in the Latin West. Astrolabes were further developed in the medieval Islamic world , where Muslim astronomers introduced angular scales to the design, adding circles indicating azimuths on the horizon . It was widely used throughout the Muslim world, chiefly as an aid to navigation and as a way of finding the Qibla ,

SECTION 50

#1732844360458

6344-467: The Mesopotamian population became literate. Massive archives of texts were recovered from the archaeological contexts of Old Babylonian scribal schools, through which literacy was disseminated. Akkadian gradually replaced Sumerian as the spoken language of Mesopotamia somewhere around the turn of the 3rd and the 2nd millennium BC. The exact dating being a matter of debate. Sumerian continued to be used as

6466-421: The Sun's brightness. However, sextants with adjustable polarizing filters have also been manufactured, where the degree of darkness is adjusted by twisting the frame of the filter. Most sextants mount a 1 or 3-power monocular for viewing. Many users prefer a simple sighting tube, which has a wider, brighter field of view and is easier to use at night. Some navigators mount a light-amplifying monocular to help see

6588-464: The Tigris unite and empty into the Persian Gulf . The arid environment ranges from the northern areas of rain-fed agriculture to the south where irrigation of agriculture is essential. This irrigation is aided by a high water table and by melting snows from the high peaks of the northern Zagros Mountains and from the Armenian Highlands, the source of the Tigris and Euphrates Rivers that give

6710-557: The ancient history of lower Mesopotamia—commenced in the early-third millennium BC with cuneiform records of early dynastic kings. This entire history ends with either the arrival of the Achaemenid Empire in the late 6th century BC or with the Muslim conquest and the establishment of the Caliphate in the late 7th century AD, from which point the region came to be known as Iraq . In the long span of this period, Mesopotamia housed some of

6832-450: The angle through which the index arm turns. The scales of the octant, sextant, quintant and quadrant are graduated from below zero to 90°, 120°, 140° and 180° respectively. For example, the sextant illustrated has a scale graduated from −10° to 142°, which is basically a quintant: the frame is a sector of a circle subtending an angle of 76° at the pivot of the index arm. The necessity for the doubled scale reading follows from consideration of

6954-744: The arc, creating inaccuracies. Many navigators purchase weatherproof cases so that their sextant can be placed outside the cabin to come to equilibrium with outside temperatures. The standard frame designs (see illustration) are supposed to equalise differential angular error from temperature changes. The handle is separated from the arc and frame so that body heat does not warp the frame. Sextants for tropical use are often painted white to reflect sunlight and remain relatively cool. High-precision sextants have an invar (a special low-expansion steel) frame and arc. Some scientific sextants have been constructed of quartz or ceramics with even lower expansions. Many commercial sextants use low-expansion brass or aluminium. Brass

7076-428: The artificial horizon's fluid. Older aircraft sextants had two visual paths, one standard and the other designed for use in open-cockpit aircraft that let one view from directly over the sextant in one's lap. More modern aircraft sextants were periscopic with only a small projection above the fuselage . With these, the navigator pre-computed their sight and then noted the difference in observed versus predicted height of

7198-454: The astrolabe was Composition and Use of Astrolabe by Christian of Prachatice , also using Messahalla, but relatively original. In 1370, the first Indian treatise on the astrolabe was written by the Jain astronomer Mahendra Suri , titled Yantrarāja . A simplified astrolabe, known as a balesilha , was used by sailors to get an accurate reading of latitude while at sea. The use of the balesilha

7320-464: The astrolabe's various functions. These ranged from the astrological, the astronomical and the religious, to navigation, seasonal and daily time-keeping, and tide tables. At the time of their use, astrology was widely considered as much of a serious science as astronomy, and study of the two went hand-in-hand. The astronomical interest varied between folk astronomy (of the pre-Islamic tradition in Arabia) which

7442-649: The back edge. The alidade is attached to the back face. An alidade can be seen in the lower right illustration of the Persian astrolabe above. When the astrolabe is held vertically, the alidade can be rotated and the sun or a star sighted along its length, so that its altitude in degrees can be read ("taken") from the graduated edge of the astrolabe; hence the word's Greek roots: "astron" (ἄστρον) = star + "lab-" (λαβ-) = to take. The alidade had vertical and horizontal cross-hairs which plots locations on an azimuthal ring called an almucantar (altitude-distance circle). An arm called

SECTION 60

#1732844360458

7564-421: The back of the devices. This was used to convert shadow lengths and the altitude of the sun, the uses of which were various from surveying to measuring inaccessible heights. Devices were usually signed by their maker with an inscription appearing on the back of the astrolabe, and if there was a patron of the object, their name would appear inscribed on the front, or in some cases, the name of the reigning sultan or

7686-404: The body to determine their position. A sight (or measure ) of the angle between the Sun , a star , or a planet , and the horizon is done with the 'star telescope ' fitted to the sextant using a visible horizon. On a vessel at sea even on misty days a sight may be done from a low height above the water to give a more definite, better horizon. Navigators hold the sextant by its handle in

7808-488: The broader sense, the historical region of Mesopotamia also includes parts of present-day Iran , Turkey , Syria and Kuwait . Mesopotamia is the site of the earliest developments of the Neolithic Revolution from around 10,000 BC. It has been identified as having "inspired some of the most important developments in human history, including the invention of the wheel , the planting of the first cereal crops ,

7930-416: The celestial equatorial plane of the celestial Tropic of Capricorn , defines the size of the astrolabe's tympanum. The center of the tympanum (and the center of the three circles) is actually the north-south axis around which Earth rotates, and therefore, the rete of the astrolabe will rotate around this point as the hours of the day pass (due to Earth's rotational motion ). The three concentric circles on

8052-445: The celestial equatorial plane, as in the image above, a grid of consecutive ellipses is constructed, allowing for the determination of a star's altitude when its rete overlaps with the designed tympanum. On the right side of the image above: When projecting the celestial meridian , it results in a straight line that overlaps with the vertical axis of the tympanum, where the zenith and nadir are located. However, when projecting

8174-466: The celestial sphere into equal sectors (like "orange slices" radiating from the zenith) are projected, a family of curves passing through the zenith projection on the tympanum is obtained. These curves, once overlaid with the rete containing the major stars, allow for determining the azimuth of a star located on the rete and rotated for a specific time of day. Severus' treatise was translated by Smith Margoliouth (1932) . Sextant A sextant

8296-404: The center of the tympanum (both the observer and the projection of the north-south axis). This implies that a portion of the celestial sphere will fall outside the outer circle of the tympanum (the projection of the celestial Tropic of Capricorn ) and, therefore, won't be represented. Additionally, when drawing circles parallel to the horizon up to the zenith ( almucantar ), and projecting them on

8418-410: The chances of the patient's recovery. Esagil-kin-apli discovered a variety of illnesses and diseases and described their symptoms in his Diagnostic Handbook . These include the symptoms for many varieties of epilepsy and related ailments along with their diagnosis and prognosis. Some treatments used were likely based off the known characteristics of the ingredients used. The others were based on

8540-696: The city of Eridu , the Akkadian kingdoms, the Third Dynasty of Ur , and the various Assyrian empires. Some of the important historical Mesopotamian leaders were Ur-Nammu (king of Ur), Sargon of Akkad (who established the Akkadian Empire), Hammurabi (who established the Old Babylonian state), Ashur-uballit I and Tiglath-Pileser I (who established the Assyrian Empire). Scientists analysed DNA from

8662-614: The cultural mix. Periodic breakdowns in the cultural system have occurred for a number of reasons. The demands for labor has from time to time led to population increases that push the limits of the ecological carrying capacity , and should a period of climatic instability ensue, collapsing central government and declining populations can occur. Alternatively, military vulnerability to invasion from marginal hill tribes or nomadic pastoralists has led to periods of trade collapse and neglect of irrigation systems. Equally, centripetal tendencies amongst city-states have meant that central authority over

8784-421: The cycles of the moon. They divided the year into two seasons: summer and winter. The origins of astronomy as well as astrology date from this time. During the 8th and 7th centuries BC, Babylonian astronomers developed a new approach to astronomy. They began studying philosophy dealing with the ideal nature of the early universe and began employing an internal logic within their predictive planetary systems. This

8906-464: The day. Thirteen of his astrolabes survive to this day. One more special example of craftsmanship in early 15th-century Europe is the astrolabe designed by Antonius de Pacento and made by Dominicus de Lanzano, dated 1420. In the 16th century, Johannes Stöffler published Elucidatio fabricae ususque astrolabii , a manual of the construction and use of the astrolabe. Four identical 16th century astrolabes made by Georg Hartmann provide some of

9028-445: The development of cursive script, mathematics , astronomy , and agriculture ". It is recognised as the cradle of some of the world's earliest civilizations. The Sumerians and Akkadians , each originating from different areas, dominated Mesopotamia from the beginning of recorded history ( c.  3100 BC ) to the fall of Babylon in 539 BC. The rise of empires, beginning with Sargon of Akkad around 2350 BC, characterized

9150-407: The direction of Mecca . Eighth-century mathematician Muhammad al-Fazari is the first person credited with building the astrolabe in the Islamic world. The mathematical background was established by Muslim astronomer Albatenius in his treatise Kitab az-Zij ( c.  920 CE ), which was translated into Latin by Plato Tiburtinus ( De Motu Stellarum ). The earliest surviving astrolabe

9272-613: The earliest evidence for batch production by division of labor . Greek painter Ieremias Palladas incorporated a sophisticated astrolabe in his 1612 painting depicting Catherine of Alexandria . The painting, entitled Catherine of Alexandria ; in addition to the saint, showed a device labelled the 'system of the universe' ( Σύστημα τοῦ Παντός ). The device featured the classical planets with their Greek names: Helios (Sun), Selene (Moon), Hermes (Mercury), Aphrodite (Venus), Ares (Mars), Zeus (Jupiter), and Cronos (Saturn). The depicted device also had celestial spheres, following

9394-532: The end of the Neo-Babylonian period. Old Aramaic , which had already become common in Mesopotamia, then became the official provincial administration language of first the Neo-Assyrian Empire , and then the Achaemenid Empire : the official lect is called Imperial Aramaic . Akkadian fell into disuse, but both it and Sumerian were still used in temples for some centuries. The last Akkadian texts date from

9516-410: The fixed ray and the object ray must therefore increase by 40°. This is the case shown in the graphic. There are two types of horizon mirrors on the market today. Both types give good results. Traditional sextants have a half-horizon mirror, which divides the field of view in two. On one side, there is a view of the horizon; on the other side, a view of the celestial object. The advantage of this type

9638-678: The horizon on moonless nights. Others prefer to use a lit artificial horizon. Professional sextants use a click-stop degree measure and a worm adjustment that reads to a minute , 1/60 of a degree . Most sextants also include a vernier on the worm dial that reads to 0.1 minute. Since 1 minute of error is about a nautical mile , the best possible accuracy of celestial navigation is about 0.1 nautical miles (190 m). At sea, results within several nautical miles, well within visual range, are acceptable. A highly skilled and experienced navigator can determine position to an accuracy of about 0.25-nautical-mile (460 m). A change in temperature can warp

9760-473: The horizon. This makes it easy to see when the bottom limb of a celestial object touches the horizon. Since most sights are of the Sun or Moon, and haze is rare without overcast, the low-light advantages of the half-horizon mirror are rarely important in practice. In both types, larger mirrors give a larger field of view, and thus make it easier to find a celestial object. Modern sextants often have 5 cm or larger mirrors, while 19th-century sextants rarely had

9882-463: The indicated stars were often engraved on the pointers in Arabic or Latin. Some astrolabes have a narrow rule or label which rotates over the rete, and may be marked with a scale of declinations . The rete, representing the sky , functions as a star chart . When it is rotated, the stars and the ecliptic move over the projection of the coordinates on the tympan. One complete rotation corresponds to

10004-460: The late 1st century AD. Early in Mesopotamia's history, around the mid-4th millennium BC, cuneiform was invented for the Sumerian language. Cuneiform literally means "wedge-shaped", due to the triangular tip of the stylus used for impressing signs on wet clay. The standardized form of each cuneiform sign appears to have been developed from pictograms . The earliest texts, 7 archaic tablets, come from

10126-408: The level of the horizon on the horizon mirror. Then the fine adjustment screw on the end of the index bar is turned until the bottom curve (the lower limb ) of the Sun just touches the horizon. " Swinging " the sextant about the axis of the telescope ensures that the reading is being taken with the instrument held vertically. The angle of the sight is then read from the scale on the arc, making use of

10248-461: The mater and tympan, the rete , a framework bearing a projection of the ecliptic plane and several pointers indicating the positions of the brightest stars , is free to rotate. These pointers are often just simple points, but depending on the skill of the craftsman can be very elaborate and artistic. There are examples of astrolabes with artistic pointers in the shape of balls, stars, snakes, hands, dogs' heads, and leaves, among others. The names of

10370-416: The measurement is relative to the horizon, the measuring pointer is a beam of light that reaches to the horizon. The measurement is thus limited by the angular accuracy of the instrument and not the sine error of the length of an alidade , as it is in a mariner's astrolabe or similar older instrument. A sextant does not require a completely steady aim, because it measures a relative angle. For example, when

10492-460: The medieval Islamic world the Arabic word al-asturlāb (i.e., astrolabe) was given various etymologies. In Arabic texts, the word is translated as ākhidhu al-nujūm ( Arabic : آخِذُ ٱلنُّجُومْ , lit.   ' star-taker ' ) – a direct translation of the Greek word. Al-Biruni quotes and criticises medieval scientist Hamza al-Isfahani , who stated: In medieval Islamic sources, there

10614-472: The methods of therapy and aetiology and the use of empiricism , logic , and rationality in diagnosis, prognosis and therapy. The text contains a list of medical symptoms and often detailed empirical observations along with logical rules used in combining observed symptoms on the body of a patient with its diagnosis and prognosis. The symptoms and diseases of a patient were treated through therapeutic means such as bandages , creams and pills . If

10736-445: The micrometer or vernier scale provided. The exact time of the sight must also be noted simultaneously, and the height of the eye above sea-level recorded. An alternative method is to estimate the current altitude (angle) of the Sun from navigation tables, then set the index bar to that angle on the arc, apply suitable shades only to the index mirror, and point the instrument directly at the horizon, sweeping it from side to side until

10858-568: The name Mesopotamia is evident from The Anabasis of Alexander , which was written in the late 2nd century AD but specifically refers to sources from the time of Alexander the Great . In the Anabasis , Mesopotamia was used to designate the land east of the Euphrates in north Syria . The Akkadian term biritum/birit narim corresponded to a similar geographical concept. Later, the term Mesopotamia

10980-414: The northern hemisphere). If, on the other hand, its altitude coincides with the inner circle (Tropic of Cancer), it indicates the summer solstice . If its altitude is on the middle circle (equator), it corresponds to one of the two equinoxes . On the right side of the image above: When projecting the horizon onto the celestial equatorial plane, it transforms into an ellipse upward-shifted relatively to

11102-420: The origins of philosophy can be traced back to early Mesopotamian wisdom , which embodied certain philosophies of life, particularly ethics , in the forms of dialectic , dialogues , epic poetry , folklore , hymns , lyrics , prose works, and proverbs . Babylonian reason and rationality developed beyond empirical observation. Babylonian thought was also based on an open-systems ontology which

11224-453: The passage of a day. The astrolabe is, therefore, a predecessor of the modern planisphere . On the back of the mater, there is often engraved a number of scales that are useful in the astrolabe's various applications. These vary from designer to designer, but might include curves for time conversions, a calendar for converting the day of the month to the sun's position on the ecliptic, trigonometric scales, and graduation of 360 degrees around

11346-441: The portion of the horizon directly below it is viewed on both mirrors. It is necessary to flip back the horizon mirror shade to be able to see the horizon more clearly on it. Releasing the index bar (either by releasing a clamping screw, or on modern instruments, using the quick-release button), and moving it towards higher values of the scale, eventually the image of the Sun will reappear on the index mirror and can be aligned to about

11468-402: The present day, allow accurate associations of relative with absolute dating for establishing the history of Mesopotamia. The Babylonian astronomers were very adept at mathematics and could predict eclipses and solstices . Scholars thought that everything had some purpose in astronomy. Most of these related to religion and omens. Mesopotamian astronomers worked out a 12-month calendar based on

11590-425: The region after that date. It has been argued that these later euphemisms are Eurocentric terms attributed to the region in the midst of various 19th-century Western encroachments. Mesopotamia encompasses the land between the Euphrates and Tigris rivers, both of which have their headwaters in the neighboring Armenian highlands . Both rivers are fed by numerous tributaries, and the entire river system drains

11712-801: The region coming under ephemeral Roman control. In 226 AD, the eastern regions of Mesopotamia fell to the Sassanid Persians . The division of the region between the Roman Byzantine Empire from 395 AD and the Sassanid Empire lasted until the 7th century Muslim conquest of Persia of the Sasanian Empire and the Muslim conquest of the Levant from the Byzantines. A number of primarily neo-Assyrian and Christian native Mesopotamian states existed between

11834-613: The region for a century as the final independent Mesopotamian realm until the modern era. In 539 BC, Mesopotamia was conquered by the Achaemenid Empire . The area was next conquered by Alexander the Great in 332 BC. After his death, it became part of the Greek Seleucid Empire . Around 150 BC, Mesopotamia was under the control of the Parthian Empire . It became a battleground between the Romans and Parthians, with western parts of

11956-441: The region its name. The usefulness of irrigation depends upon the ability to mobilize sufficient labor for the construction and maintenance of canals, and this, from the earliest period, has assisted the development of urban settlements and centralized systems of political authority. Agriculture throughout the region has been supplemented by nomadic pastoralism, where tent-dwelling nomads herded sheep and goats (and later camels) from

12078-432: The relations of the fixed ray (between the mirrors), the object ray (from the sighted object) and the direction of the normal perpendicular to the index mirror. When the index arm moves by an angle, say 20°, the angle between the fixed ray and the normal also increases by 20°. But the angle of incidence equals the angle of reflection so the angle between the object ray and the normal must also increase by 20°. The angle between

12200-425: The right hand, avoiding touching the arc with the fingers. For a Sun sight, a filter is used to overcome the glare such as "shades" covering both index mirror and the horizon mirror designed to prevent eye damage. Initially, with the index bar set to zero and the shades covering both mirrors, the sextant is aimed at the sun until it can be viewed on both mirrors through the telescope, then lowered vertically until

12322-461: The river pastures in the dry summer months, out into seasonal grazing lands on the desert fringe in the wet winter season. The area is generally lacking in building stone, precious metals, and timber, and so historically has relied upon long-distance trade of agricultural products to secure these items from outlying areas. In the marshlands to the south of the area, a complex water-borne fishing culture has existed since prehistoric times and has added to

12444-416: The sighted celestial object on a globe. The intersection of that circle with a dead-reckoning track, or another sighting, gives a more precise location. Sextants can be used very accurately to measure other visible angles, for example between one heavenly body and another and between landmarks ashore. Used horizontally, a sextant can measure the apparent angle between two landmarks such as a lighthouse and

12566-465: The subsequent 2,000 years of Mesopotamian history, marked by the succession of kingdoms and empires such as the Akkadian Empire . The early second millennium BC saw the polarization of Mesopotamian society into Assyria in the north and Babylonia in the south. From 900 to 612 BC, the Neo-Assyrian Empire asserted control over much of the ancient Near East. Subsequently, the Babylonians, who had long been overshadowed by Assyria, seized power , dominating

12688-534: The syllabary were all arranged and named, and elaborate lists were drawn up. Many Babylonian literary works are still studied today. One of the most famous of these was the Epic of Gilgamesh , in twelve books, translated from the original Sumerian by a certain Sîn-lēqi-unninni , and arranged upon an astronomical principle. Each division contains the story of a single adventure in the career of Gilgamesh . The whole story

12810-550: The symbolic qualities. Mesopotamian people invented many technologies including metal and copper-working, glass and lamp making, textile weaving, flood control , water storage, and irrigation. They were also one of the first Bronze Age societies in the world. They developed from copper, bronze, and gold on to iron. Palaces were decorated with hundreds of kilograms of these very expensive metals. Also, copper, bronze, and iron were used for armor as well as for different weapons such as swords, daggers, spears, and maces . According to

12932-471: The teacher of the astrolabist has also been found to appear inscribed in this place. The date of the astrolabe's construction was often also signed, which has allowed historians to determine that these devices are the second oldest scientific instrument in the world. The inscriptions on astrolabes also allowed historians to conclude that astronomers tended to make their own astrolabes, but that many were also made to order and kept in stock to sell, suggesting there

13054-454: The tympanum are useful for determining the exact moments of solstices and equinoxes throughout the year: if the sun's altitude at noon on the rete is known and coincides with the outer circle of the tympanum (Tropic of Capricorn), it signifies the winter solstice (the sun will be at the zenith for an observer at the Tropic of Capricorn, meaning summer in the southern hemisphere and winter in

13176-603: The universal astrolobe designed by Ibn al-Sarraj of Aleppo (a.k.a. Ahmad bin Abi Bakr; fl. 1328) as "the most sophisticated astronomical instrument from the entire Medieval and Renaissance periods". English author Geoffrey Chaucer ( c.  1343–1400 ) compiled A Treatise on the Astrolabe for his son, mainly based on a work by Messahalla or Ibn al-Saffar . The same source was translated by French astronomer and astrologer Pélerin de Prusse and others. The first printed book on

13298-509: The use of the astrolabe in Mensura Astrolai during the 11th century. Peter of Maricourt wrote a treatise on the construction and use of a universal astrolabe in the last half of the 13th century entitled Nova compositio astrolabii particularis . Universal astrolabes can be found at the History of Science Museum, Oxford . David A. King, historian of Islamic instrumentation, describes

13420-418: The volume of the frustum of a cone or a square pyramid was incorrectly taken as the product of the height and half the sum of the bases. Also, there was a recent discovery in which a tablet used π as 25/8 (3.125 instead of 3.14159~). The Babylonians are also known for the Babylonian mile, which was a measure of distance equal to about seven modern miles (11 km). This measurement for distances eventually

13542-679: The whole region, when imposed, has tended to be ephemeral, and localism has fragmented power into tribal or smaller regional units. These trends have continued to the present day in Iraq. The prehistory of the Ancient Near East begins in the Lower Paleolithic period. Therein, writing emerged with a pictographic script, Proto-cuneiform , in the Uruk IV period ( c.  late 4th millennium BC ). The documented record of actual historical events—and

13664-778: The world's most ancient highly developed, and socially complex states. The region was one of the four riverine civilizations where writing was invented, along with the Nile valley in Ancient Egypt , the Indus Valley civilization in the Indian subcontinent , and the Yellow River in Ancient China . Mesopotamia housed historically important cities such as Uruk , Nippur , Nineveh , Assur and Babylon , as well as major territorial states such as

13786-539: Was a variation of both the astrolabe and the armillary sphere , invented during the Middle Ages by astronomers and inventors in the Islamic world. The earliest description of the spherical astrolabe dates to Al-Nayrizi ( fl. 892–902). In the 12th century, Sharaf al-Dīn al-Tūsī invented the linear astrolabe , sometimes called the "staff of al-Tusi", which was The first known metal astrolabe in Western Europe

13908-430: Was an important contribution to astronomy and the philosophy of science and some scholars have thus referred to this new approach as the first scientific revolution. This new approach to astronomy was adopted and further developed in Greek and Hellenistic astronomy. In Seleucid and Parthian times, the astronomical reports were thoroughly scientific. How much earlier their advanced knowledge and methods were developed

14030-478: Was concerned with celestial and seasonal observations, and mathematical astronomy, which would inform intellectual practices and precise calculations based on astronomical observations. In regard to the astrolabe's religious function, the demands of Islamic prayer times were to be astronomically determined to ensure precise daily timings, and the qibla , the direction of Mecca towards which Muslims must pray, could also be determined by this device. In addition to this,

14152-451: Was converted to a time-mile used for measuring the travel of the Sun, therefore, representing time. The roots of algebra can be traced to the ancient Babylonia who developed an advanced arithmetical system with which they were able to do calculations in an algorithmic fashion. The Babylonian clay tablet YBC 7289 ( c.  1800 –1600 BC) gives an approximation of √ 2 in four sexagesimal figures, 1 24 51 10 , which

14274-412: Was instrumental in early map-making . The Babylonians also had theorems on how to measure the area of several shapes and solids. They measured the circumference of a circle as three times the diameter and the area as one-twelfth the square of the circumference, which would be correct if π were fixed at 3. The volume of a cylinder was taken as the product of the area of the base and the height; however,

14396-506: Was measured, can be used to calculate a position line on a nautical or aeronautical chart —for example, sighting the Sun at noon or Polaris at night (in the Northern Hemisphere) to estimate latitude (with sight reduction ). Sighting the height of a landmark can give a measure of distance off and, held horizontally, a sextant can measure angles between objects for a position on a chart . A sextant can also be used to measure

14518-618: Was more generally applied to all the lands between the Euphrates and the Tigris , thereby incorporating not only parts of Syria but also almost all of Iraq and southeastern Turkey . The neighbouring steppes to the west of the Euphrates and the western part of the Zagros Mountains are also often included under the wider term Mesopotamia . A further distinction is usually made between Northern or Upper Mesopotamia and Southern or Lower Mesopotamia . Upper Mesopotamia, also known as

14640-698: Was promoted by Prince Henry (1394–1460) while navigating for Portugal. The astrolabe was almost certainly first brought north of the Pyrenees by Gerbert of Aurillac (future Pope Sylvester II ), where it was integrated into the quadrivium at the school in Reims, France, sometime before the turn of the 11th century. In the 15th century, French instrument maker Jean Fusoris ( c.  1365–1436 ) also started remaking and selling astrolabes in his shop in Paris , along with portable sundials and other popular scientific devices of

14762-515: Was some contemporary market for the devices. The construction and design of astrolabes are based on the application of the stereographic projection of the celestial sphere . The point from which the projection is usually made is the South Pole . The plane onto which the projection is made is that of the Equator . The tympanum captures the celestial coordinate axes upon which the rete will rotate. It

14884-450: Was the first recorded. Mesopotamians believed that the world was a flat disc, surrounded by a huge, holed space, and above that, heaven . They believed that water was everywhere, the top, bottom and sides, and that the universe was born from this enormous sea. Mesopotamian religion was polytheistic . Although the beliefs described above were held in common among Mesopotamians, there were regional variations. The Sumerian word for universe

#457542