In the ancient Mediterranean world , the classical compass winds were names for the points of geographic direction and orientation, in association with the winds as conceived of by the ancient Greeks and Romans . Ancient wind roses typically had twelve winds and thus twelve points of orientation, sometimes reduced to eight or increased to twenty-four.
112-450: Four Winds may refer to: Classical compass winds , the winds associated with the points of the compass In Mythology [ edit ] The Anemoi , personifications of winds in Greek mythology The Four Winds (Mesopotamian) Businesses [ edit ] Four Winds Casinos , Michigan, United States Four Winds International ,
224-579: A 2009 album by The Lightning Seeds "Four Winds", a song from the 1999 album Guitars by Mike Oldfield Places [ edit ] Four Winds (New Orleans) , a historic apartment building in New Orleans, Louisiana, United States Casinos in Michigan, United States: Four Winds Dowagiac Four Winds Hartford Four Winds New Buffalo Four Winds Field at Coveleski Stadium , baseball facility, South Bend, Indiana, United States Four Winds,
336-462: A collective of north winds, the Boreae . It is said that the geographer Eratosthenes of Cyrene (c. 200 BCE), realizing that many winds presented only slight variations, reduced twelve winds down to eight principal winds. Eratosthenes's own work has been lost, but the story is reported by Vitruvius , who goes on to say Eratosthenes came to this conclusion in the course of measuring the circumference of
448-469: A defined initial bearing. That is, upon taking an initial bearing, one proceeds along the same bearing, without changing the direction as measured relative to true or magnetic north. Most modern navigation relies primarily on positions determined electronically by receivers collecting information from satellites. Most other modern techniques rely on finding intersecting lines of position or LOP. A line of position can refer to two different things, either
560-543: A degree or so. Similar to latitude, the longitude of a place on Earth is the angular distance east or west of the prime meridian or Greenwich meridian . Longitude is usually expressed in degrees (marked with °) ranging from 0° at the Greenwich meridian to 180° east and west. Sydney , for example, has a longitude of about 151° east . New York City has a longitude of 74° west . For most of history, mariners struggled to determine longitude. Longitude can be calculated if
672-478: A distance produces a circle or arc of position. Circles, arcs, and hyperbolae of positions are often referred to as lines of position. If the navigator draws two lines of position, and they intersect he must be at that position. A fix is the intersection of two or more LOPs. If only one line of position is available, this may be evaluated against the dead reckoning position to establish an estimated position. Lines (or circles) of position can be derived from
784-587: A few meters using time signals transmitted along a line of sight by radio from satellites . Receivers on the ground with a fixed position can also be used to calculate the precise time as a reference for scientific experiments. As of October 2011, only the United States NAVSTAR Global Positioning System (GPS) and the Russian GLONASS are fully globally operational GNSSs. The European Union 's Galileo positioning system
896-452: A four wind-rose. Writing several centuries later, Strabo (c. 10 BC) notes that some contemporaries took Homer's ambiguity to imply that the Homeric system may already anticipate the summer and winter distinction later made famous by Aristotle . This refers to the fact that the "east" (sunrise) and "west" (sunset) are not stable on the horizon, but depend on the season, i.e. during the winter,
1008-407: A hundred years, from about 1767 until about 1850, mariners lacking a chronometer used the method of lunar distances to determine Greenwich time to find their longitude. A mariner with a chronometer could check its reading using a lunar determination of Greenwich time. In navigation, a rhumb line (or loxodrome) is a line crossing all meridians of longitude at the same angle, i.e. a path derived from
1120-607: A later chapter, Pliny goes on to say that Aquilo, in the summer, turns into the Etesian winds, the periodic wind already referred to by Aristotle. Pliny also mentions, for the other half-winds, Phoenicias (for SSE, not Euronotus), Libonotus (SSW), and Thrascias (NNW). It is apparent Pliny had recently read Aristotle and sought to resurrect some of the abandoned Aristotelean names (Boreas/Aparctias, Meses, Etesian winds, Phoenicias, he even mentions Olympias and Sciron as local Greek winds), albeit they appear rather awkwardly when inserted into
1232-581: A later note that "Caecias" is mentioned in Aristotle (but does not give it a position). Aquilo/Boreas seem well-enthroned at NE. Another surprise is the re-emergence of Eurus in the East, where it has not been seen since Homer. He seems to treat Eurus as a Latin name, giving the Aristotelean Apeliotes as the Greek equivalent, and reducing Subsolanus to a mere variant "from Roman sailors". With Eurus now absent in
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#17328450183351344-402: A line on a chart or a line between the observer and an object in real life. A bearing is a measure of the direction to an object. If the navigator measures the direction in real life, the angle can then be drawn on a nautical chart and the navigator will be somewhere on that bearing line on the chart. In addition to bearings, navigators also often measure distances to objects. On the chart,
1456-529: A motorhome manufacturer (now known as Thor Motor Coach ) Four Winds Brewing , Vancouver, BC, Canada Literature [ edit ] Four Winds (play) , a 1953 play by Alex Atkinson The Four Winds (novel) , by Kristin Hannah , 2021 Music [ edit ] Four Winds (EP) , a 2007 EP by the indie rock band Bright Eyes "Four Winds", the first track on the EP Four Winds (album) ,
1568-450: A number of stars in succession to give a series of overlapping lines of position. Where they intersect is the celestial fix. The Moon and Sun may also be used. The Sun can also be used by itself to shoot a succession of lines of position (best done around local noon) to determine a position. In order to accurately measure longitude, the precise time of a sextant sighting (down to the second, if possible) must be recorded. Each second of error
1680-491: A particular wind by its qualities and referred to it by a familiar name. The final step, completing the circle, was to use the proper names of the winds to denote general cardinal directions of the compass rose . This would take a little longer to work itself through. In the Hebrew Bible , there is frequent reference to four cardinal directions . The names of the directions seem to be associated with physical landmarks for
1792-399: A particularly good navigation system for ships and aircraft that might be flying at a distance from land. RDFs works by rotating a directional antenna and listening for the direction in which the signal from a known station comes through most strongly. This sort of system was widely used in the 1930s and 1940s. RDF antennas are easy to spot on German World War II aircraft, as loops under
1904-418: A radio time signal. Times and frequencies of radio time signals are listed in publications such as Radio Navigational Aids . The second critical component of celestial navigation is to measure the angle formed at the observer's eye between the celestial body and the sensible horizon. The sextant, an optical instrument, is used to perform this function. The sextant consists of two primary assemblies. The frame
2016-665: A reference to Mount Olympus and the Sciros rocks in Megara . The remaining winds also seem to be geographical. Caecias ( καικίας ) means from Caicus, a river in Mysia , a region northeast of the Aegean. Lips ( λίψ ) means "from Libya ", to the southwest of Greece (although an alternative theory connects it to "leibo", λείβω , same root as libation , meaning pouring, because this wind brought rain). Phoenicias ( φοινικίας ) comes "from Phoenicia " (to
2128-482: A reference to sunrise and sunset . The archaic Greek poet Homer (c. 800 BC) refers to the four winds by name – Boreas, Eurus, Notos, Zephyrus – in his Odyssey , and in the Iliad . However, at some points, Homer seems to imply two more: a northwest wind and a southwest wind. Some have taken this to imply that Homer may have had as many as eight winds. However, others remain unconvinced, and insist Homer only had
2240-602: A reference to the Mistral ) He also notes Iapyx (already mentioned, but first here explained as a local wind from Iapygia in Apulia ) and periodic regional Etesian winds and the "Prodromi" (NW fore-winds, in Greek, πρόδρομοι ). The "Vatican table" is a marble Roman anemoscope (wind-vane) dating from the 2nd or 3rd Century CE, held by the Vatican Museums . Divided into twelve equal sides, on each of its sides, it has inscribed
2352-485: A significant step in the evolution of the compass rose. Depending on how Ventorum Situs is dated, Timosthenes can be credited with turning Aristotle's asymmetric ten-wind compass into a symmetric twelve-wind compass, by introducing the SSW wind (Leuconotos/Libonotos) omitted by Aristotle and Theophrastus and assigning the compound "Euronotos" (already alluded to by Aristotle, no mention of Theophrastus's Orthonotos here) in place of
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#17328450183352464-400: A single object," "two or more bearings," "tangent bearings," and "two or more ranges." Radar can also be used with ECDIS as a means of position fixing with the radar image or distance/bearing overlaid onto an Electronic nautical chart . Parallel indexing is a technique defined by William Burger in the 1957 book The Radar Observer's Handbook . This technique involves creating a line on
2576-426: A suburb of south Belfast , Northern Ireland See also [ edit ] Four Winns , former American boat-builder The Four Winds of Love , series of novels by Compton Mackenzie Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title Four Winds . If an internal link led you here, you may wish to change the link to point directly to
2688-404: A sufficient depth of water below the hull as well as a consideration for squat . It may also involve navigating a ship within a river, canal or channel in close proximity to land. A military navigation team will nearly always consist of several people. A military navigator might have bearing takers stationed at the gyro repeaters on the bridge wings for taking simultaneous bearings, while
2800-513: A tentative relationship with actual navigation . The Classical 12-point wind rose was eventually displaced by the modern compass rose (8-point, 16-point and 32-point), adopted by seafarers during the Middle Ages . It is uncertain when or why the human sense of geographic orientation and direction became associated with winds . It is probable that for ancient settled populations, local physical landmarks (e.g. mountains, deserts, settlements) were
2912-413: A variety of sources: There are some methods seldom used today such as "dipping a light" to calculate the geographic range from observer to lighthouse. Methods of navigation have changed through history. Each new method has enhanced the mariner's ability to complete his voyage. One of the most important judgments the navigator must make is the best method to use. Some types of navigation are depicted in
3024-449: Is Pulsar navigation , which compares the X-ray bursts from a collection of known pulsars in order to determine the position of a spacecraft. This method has been tested by multiple space agencies, such as NASA and ESA . A radio direction finder or RDF is a device for finding the direction to a radio source. Due to radio's ability to travel very long distances "over the horizon", it makes
3136-606: Is yam ("sea", meaning the Mediterranean Sea ). Orientation seems to be to the East, in the direction of the rising sun, with the result that the terms kedem , saphon and negev became generalized with "facing", "left" and "right" side of anything. The association of cardinal directions with winds is implied at several places in the Old Testament. "Four winds" are referred to in the Bible in several places. Kedem (East)
3248-436: Is a quartz crystal oscillator. The quartz crystal is temperature compensated and is hermetically sealed in an evacuated envelope. A calibrated adjustment capability is provided to adjust for the aging of the crystal. The chronometer is designed to operate for a minimum of one year on a single set of batteries. Observations may be timed and ship's clocks set with a comparing watch, which is set to chronometer time and taken to
3360-425: Is a rigid triangular structure with a pivot at the top and a graduated segment of a circle, referred to as the "arc", at the bottom. The second component is the index arm, which is attached to the pivot at the top of the frame. At the bottom is an endless vernier which clamps into teeth on the bottom of the "arc". The optical system consists of two mirrors and, generally, a low power telescope. One mirror, referred to as
3472-532: Is already in Timosthenes, but Aparctias's demotion from the N is novel). When he goes on to discuss half-winds, Pliny re-introduces Caecis as lying "between Aquilo and Subsolanus", thus restoring it effectively to its NE position. Evidently reading Aristotle, Pliny tries to insert long-lost Meses again "between Boreas (= Aquilo) and Caecis", thus placing Meses in a position that (in a modern 32-point compass) would be called " Northeast by north ". Confusing matters, in
Four Winds - Misplaced Pages Continue
3584-434: Is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks. All navigational techniques involve locating the navigator's position compared to known locations or patterns. Navigation, in a broader sense, can refer to any skill or study that involves the determination of position and direction . In this sense, navigation includes orienteering and pedestrian navigation. In
3696-567: Is an attempt to derive the etymology of the winds. As they are often named after a particular locality from where they seem to blow, different places in the Hellenistic world have come up with variant local names for the winds. In the list given in the Ventorum Situs : The Greek-Roman physician Agathemerus (c. 250 CE), in his Geographia , gives the eight principal winds. But Agathemerus goes on to note that nearly five hundred years earlier,
3808-475: Is asymmetric. Specifically, the half-winds would be at 22½° on either side of the North, while the principal eight would be at 45° angles from each other. However, an alternative hypothesis is that they will be more equally spaced around 30° from each other. By way of guidance, Aristotle mentions that the easterly and westerly positions are that of the sun as seen on the horizon at dawn and at dusk at different times of
3920-462: Is centered at Athens , it has been calculated that this construction would yield a symmetric compass rose with approximately 30° angles all around. If set out on a compass card, Aristotle's system could be conceived of as a twelve-wind rose with four cardinal winds (N, E, S, W), four "solstitial winds" (loosely speaking, NW, NE, SE, SW), two "polar winds" (roughly NNW, NNE) and two "non-winds" (SSW, SSE). Aristotle explicitly groups Aparctias (N) and
4032-1027: Is considered to be the V-2 guidance system deployed by the Germans in 1942. However, inertial sensors are traced to the early 19th century. The advantages INSs led their use in aircraft, missiles, surface ships and submarines. For example, the U.S. Navy developed the Ships Inertial Navigation System (SINS) during the Polaris missile program to ensure a reliable and accurate navigation system to initial its missile guidance systems. Inertial navigation systems were in wide use until satellite navigation systems (GPS) became available. INSs are still in common use on submarines (since GPS reception or other fix sources are not possible while submerged) and long-range missiles. Not to be confused with satellite navigation, which depends upon satellites to function, space navigation refers to
4144-441: Is equivalent to 15 seconds of longitude error, which at the equator is a position error of .25 of a nautical mile, about the accuracy limit of manual celestial navigation. The spring-driven marine chronometer is a precision timepiece used aboard ship to provide accurate time for celestial observations. A chronometer differs from a spring-driven watch principally in that it contains a variable lever device to maintain even pressure on
4256-478: Is not affected by adverse weather conditions and it cannot be detected or jammed. Its disadvantage is that since the current position is calculated solely from previous positions and motion sensors, its errors are cumulative, increasing at a rate roughly proportional to the time since the initial position was input. Inertial navigation systems must therefore be frequently corrected with a location 'fix' from some other type of navigation system. The first inertial system
4368-449: Is particularly useful due to their high power and location near major cities. Decca , OMEGA , and LORAN-C are three similar hyperbolic navigation systems. Decca was a hyperbolic low frequency radio navigation system (also known as multilateration ) that was first deployed during World War II when the Allied forces needed a system which could be used to achieve accurate landings. As
4480-455: Is reasonable for the navigator to simply monitor the progress of the ship along the chosen track, visually ensuring that the ship is proceeding as desired, checking the compass, sounder and other indicators only occasionally. If a pilot is aboard, as is often the case in the most restricted of waters, his judgement can generally be relied upon, further easing the workload. But should the ECDIS fail,
4592-634: Is said to have been built by Andronicus of Cyrrhus , of uncertain dates. From the style of the sculptures the tower is usually dated around 50 BC, not long before Varro and Vitruvius mention it. An alternative possibility is that it was part of the generosity of Attalus III of Pergamon (d. 131 BC) who built the Stoa of Attalus in the city. Either way, it is after Eratosthenes. It gives as its eight winds Boreas (not Aparctias, N), Caecias (NE), Apeliotes (E), Eurus (SE), Notos (S), Lips (SW), Zephyrus (W) and Sciron (NW, variant of Argestes). Boreas' reappearance in
Four Winds - Misplaced Pages Continue
4704-408: Is that it may come from "boros" meaning "voracious". Another is that it comes from the phrase ἀπὸ τῆς βοῆς ("from the roar"), a reference to its violent and loud noise. Notos probably comes from "notios" ("moist", a reference to the warm rains and storms brought from the south). Eurus and Zephyrus seem to come from "brightness" (q.v. Eos ) and "gloominess" ("zophos") respectively, doubtlessly
4816-555: Is used frequently as the name of a scorching wind that blows from the east. It is related to the modern word קדימה " kadima ", meaning "forward". There are several passages referring to the scattering of people "to all the winds". Unlike the Biblical Israelites, the early Greeks maintained two separate and distinct systems of cardinal directions and winds, at least for a while. Astral phenomena were used to define four cardinal points : arctos ( ἄρκτος , "bear",
4928-485: The Peripatetic school , in his On Weather Signs and "On Winds" (c. 300 BCE), adopted the same wind system as Aristotle, with only some slight differences, e.g. Theophrastus misspelled Thrascias as "Thracias" and seemed to distinguish between Apractias and Boreas (perhaps as " North by west " and "North" wind respectively). In the pseudo-Aristotelean fragment Ventorum Situs (often attributed to Theophrastus ), there
5040-595: The Phoenicias wind for the SSE (blows locally in some places), but suggests nothing for SSW. So, seen this way, Aristotle really has an asymmetric windrose of ten winds, as two winds are effectively missing or only local. (Variants: Olympias ( ὀλυμπίας ), Sciron ( σκίρων ) Notice that in the Aristotelean system, old Eurus is shunted from its traditional position in the cardinal East by Apeliotes ( ἀπηλιώτης ), meaning "from
5152-546: The Pole Star (at that time, Kochab in the Ursa Minor ) as the better indicator of the North seems to have emerged a little later (it is said Thales introduced this, probably learned from Phoenician seafarers). Distinct from these cardinal points, the ancient Greeks had four winds ( Anemoi ). The peoples of early Greece reportedly conceived of only two winds – the winds from the north, known as Boreas ( Βορέας ), and
5264-868: The Spanish monarchs funded Christopher Columbus 's expedition to sail west to reach the Indies by crossing the Atlantic, which resulted in the Discovery of the Americas . In 1498, a Portuguese expedition commanded by Vasco da Gama reached India by sailing around Africa, opening up direct trade with Asia . Soon, the Portuguese sailed further eastward, to the Spice Islands in 1512, landing in China one year later. The first circumnavigation of
5376-537: The United States in cooperation with six partner nations. OMEGA was developed by the United States Navy for military aviation users. It was approved for development in 1968 and promised a true worldwide oceanic coverage capability with only eight transmitters and the ability to achieve a four-mile (6 km) accuracy when fixing a position. Initially, the system was to be used for navigating nuclear bombers across
5488-514: The Ursa Major , for North), anatole ( ἀνατολή , "sunrise" or eos "dawn", East), mesembria ( μεσημβρία , "noon", South) and dysis ( δύσις , "sunset" or hesperus , "evening", West). Heraclitus , in particular, suggests that a meridian drawn between the north ( arctos ) and its opposite could be used to divide East from West. Homer already spoke of Greeks sailing with Ursa Major (or "Wagon"/"Wain") for orientation. The identification of
5600-585: The meteorological properties of the winds, e.g. that the winds on the NW-SE axis are generally dry, while the NE-SW winds are wet (NE producing heavier clouds than SW). N and NNE bring snow. Winds from the whole northwestern sector (NW, NNW, N) are described as cold, strong, cloud-clearing winds that can bring lightning and hurricanes with them. Aristotle also makes special note of the periodic bending summer Etesian winds, which comes from different directions depending on where
5712-465: The true north ( Pole Star , Septentrio). Pliny the Elder in his Natural History (C. 77 CE) after noting that twelve was an exaggeration, goes on to note that the "moderns" have reduced it to eight. He lists them as Septentrio (N), Aquilo (NNE), Subsolanus (E), Vulturnus (SE), Auster (S), Africus (SW), Favonius (W) and Corus (NW). Notice that Caecias (NE) is not part of this octet. Instead, Pliny puts
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#17328450183355824-400: The "index mirror" is fixed to the top of the index arm, over the pivot. As the index arm is moved, this mirror rotates, and the graduated scale on the arc indicates the measured angle ("altitude"). The second mirror, referred to as the "horizon glass", is fixed to the front of the frame. One half of the horizon glass is silvered and the other half is clear. Light from the celestial body strikes
5936-451: The 1530s, from Latin navigationem (nom. navigatio ), from navigatus , pp. of navigare "to sail, sail over, go by sea, steer a ship," from navis "ship" and the root of agere "to drive". Roughly, the latitude of a place on Earth is its angular distance north or south of the equator . Latitude is usually expressed in degrees (marked with °) ranging from 0° at the Equator to 90° at
6048-503: The Elder , are adamant that Homer mentioned only four winds. Hesiod (c. 700 BCE) in his Theogony (c. 735) gives the four winds mythical personification as gods, the Anemoi ( Ἄνεμοι ), the children of the Titan gods Astraeus (stars) and Eos (dawn). But Hesiod himself refers to only three winds by name – Boreas , Notos and Zephyrus – which he called the "good winds" and the "children of
6160-526: The European medieval period, navigation was considered part of the set of seven mechanical arts , none of which were used for long voyages across open ocean. Polynesian navigation is probably the earliest form of open-ocean navigation; it was based on memory and observation recorded on scientific instruments like the Marshall Islands Stick Charts of Ocean Swells . Early Pacific Polynesians used
6272-536: The North Pole to Russia. Later, it was found useful for submarines. Due to the success of the Global Positioning System the use of Omega declined during the 1990s, to a point where the cost of operating Omega could no longer be justified. Omega was terminated on September 30, 1997, and all stations ceased operation. LORAN is a terrestrial navigation system using low frequency radio transmitters that use
6384-578: The North and South poles. The latitude of the North Pole is 90° N, and the latitude of the South Pole is 90° S. Mariners calculated latitude in the Northern Hemisphere by sighting the pole star ( Polaris ) with a sextant and using sight reduction tables to correct for height of eye and atmospheric refraction. The height of Polaris in degrees above the horizon is the latitude of the observer, within
6496-456: The North slot in place of Aparctias is notable. The winds are personified in stone reliefs as gods ( Anemoi ) at the top of the faces. Vitruvius says the tower was topped with a weather vane . The Greek wind system was adopted by the Romans, partly under their Greek nomenclature, but increasingly also under new Latin names. Roman poet Virgil , in his Georgics (c. 29 BCE) refers to several of
6608-548: The North, Boreas shunted to NNE, Euronotus instead of Phoenicias, Circius as alternate of Thrascias). The differences of De Mundo from Timosthenes are that (1) it introduces Libophoenix as another name for Libonotos (Leuconotos not mentioned); (2) two alternates to Argestes are mentioned – Iapyx (as in the Ventorum ) and Olympias (as in Aristotle) (Timosthenes mentions no variants for this wind), (3) like Aristotle, De Mundo refers to
6720-669: The Philippines, trying to find a maritime path back to the Americas , but was unsuccessful. The eastward route across the Pacific, also known as the tornaviaje (return trip) was only discovered forty years later, when Spanish cosmographer Andrés de Urdaneta sailed from the Philippines, north to parallel 39°, and hit the eastward Kuroshio Current which took its galleon across the Pacific. He arrived in Acapulco on October 8, 1565. The term stems from
6832-589: The SE, Euronotus (previously SSE) is promoted to the vacant SE position. Finally, a new name, Caurus , is introduced as the NW wind. This is almost certainly a misspelling of Corus (NW). Aulus Gellius gives some information about local winds. He mentions Circius as a local wind in Gaul , known for its dizzying, circular motion, and notes its alternate spelling Cercius in Hispania (probably
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#17328450183356944-638: The Sun" or from "the heat of the Sun". Old Boreas is mentioned only as an alternative name to Aparctias ( ἀπαρκτίας ), which means "from the Bear", that is, the Ursa Major , the Arctic Circle . Among the new winds are the Argestes ( ἀργέστης ) meaning "clearing" or "brightening", a reference to the northwest wind sweeping away clouds. Argestes's variants, Olympias ( ὀλυμπίας ) and Sciron ( σκίρων ) are local Athenian names,
7056-512: The ancient Israelites living in the region of Judea , e.g. East is referred to as kedem , which may derive from "edom" ("red"), and may be a reference to the color of the rising dawn , or the red sandstone cliffs of the Land of Edom to the east; North is referred to as saphon , from Mount Zaphon on the northern edge of Syria, South is often negev , from the Negev desert to the south, and West
7168-492: The bridge wing for recording sight times. In practice, a wrist watch coordinated to the nearest second with the chronometer will be adequate. A stop watch, either spring wound or digital, may also be used for celestial observations. In this case, the watch is started at a known GMT by chronometer, and the elapsed time of each sight added to this to obtain GMT of the sight. All chronometers and watches should be checked regularly with
7280-444: The cardinal winds, e.g. as western winds bring rain, then when Homer says a "stormy Boreas" he means a different wind from a "loud Boreas" (i.e. wet north = NW, loud north = N) Nonetheless, while it seems that Homer may have realized that there were more than four winds, he did not use those epithets systematically enough to permit us to conclude that he also embraced a six- or eight-point windrose. Other classical writers, e.g. Pliny
7392-421: The civilian navigator on a merchant ship or leisure craft must often take and plot their position themselves, typically with the aid of electronic position fixing. While the military navigator will have a bearing book and someone to record entries for each fix, the civilian navigator will simply pilot the bearings on the chart as they are taken and not record them at all. If the ship is equipped with an ECDIS , it
7504-673: The contemporary 12-wind compass schema. In his Attic Nights (written c. 159), the Athens -raised Latin writer Aulus Gellius , possibly inspired by the Tower of the Winds in that city, reduces the Latin rose to from twelve to eight winds, the principal winds, for which he gives both the Latin and Greek terms. He lists them as: Among the novelties is the disappearance of Caecias (NE, like in Pliny), although he does make
7616-639: The earth was completed in 1522 with the Magellan-Elcano expedition , a Spanish voyage of discovery led by Portuguese explorer Ferdinand Magellan and completed by Spanish navigator Juan Sebastián Elcano after the former's death in the Philippines in 1521. The fleet of seven ships sailed from Sanlúcar de Barrameda in Southern Spain in 1519, crossed the Atlantic Ocean and after several stopovers rounded
7728-411: The earth, and felt there were really only eight equally sized sectors, and that other winds were but local variations of these eight principal winds . If true, that would make Eratosthenes the inventor of the eight-wind compass rose . Eratosthenes was a disciple of Timosthenes and is said to have drawn principally from his work. But they part ways on this. Both recognized that Aristotle's ten-wind rose
7840-562: The first Greek to go beyond treating these "winds" merely as meteorological phenomena and to begin viewing them properly as points of geographic direction. Timosthenes (through Agathemerus) assigns each of the 12 winds to geographical locations and peoples (relative to Rhodes ): Modern scholars to conjecture that Timosthenes, in his lost periplus , might have made ample use of these winds for sailing directions (which may help explain Agathemerus's eagerness to credit Timosthenes for "inventing"
7952-480: The half-wind Aquilo (NNE) there instead. It seems Pliny is aware Aquilo is a half-wind, because since he says it lies "in between Septentrio and the summer sunrise" (although in a later chapter he places it at the summer sunrise). If the first version is taken, this means Pliny's eight-wind compass is asymmetric. Pliny goes on to mention that Aquilo is also "named Aparctias and Boreas" (the Boreas identification with NNE
8064-522: The half-winds Thrascias (NNW) and Meses (NNE) together as "north winds" and Argestes (NW) and Zephyrus (W) together as "west winds" — but he goes on to note that both the north and west winds could be classified as "generally northerly" ( Boreae ), since they all tend to be cold. Similarly Lips (SW) and Notos (S) are "south winds" and Eurus (SE) and Apeliotes (E) are "east winds", but once again, both south and east winds are "generally southerly" ( Notiae ) because are all relatively warm (Aristotle reasons that as
8176-426: The horizon or more preferably a star, each time the sextant is used. The practice of taking celestial observations from the deck of a rolling ship, often through cloud cover and with a hazy horizon, is by far the most challenging part of celestial navigation. Inertial navigation system (INS) is a dead reckoning type of navigation system that computes its position based on motion sensors. Before actually navigating,
8288-480: The index mirror and is reflected to the silvered portion of the horizon glass, then back to the observer's eye through the telescope. The observer manipulates the index arm so the reflected image of the body in the horizon glass is just resting on the visual horizon, seen through the clear side of the horizon glass. Adjustment of the sextant consists of checking and aligning all the optical elements to eliminate "index correction". Index correction should be checked, using
8400-430: The initial and most immediate markers of general direction ("towards the coast", "towards the hills", "towards the lands of Xanadu", etc.). Astral phenomena, in particular the position of the sun at dawn and dusk, were also used to denote direction. The association of geographic direction with wind was another source. It was probably farming populations, attentive to rain and temperature for their crops, that noticed
8512-662: The initial latitude and longitude and the INS's physical orientation relative to the Earth (e.g., north and level) are established. After alignment, an INS receives impulses from motion detectors that measure (a) the acceleration along three axes (accelerometers), and (b) rate of rotation about three orthogonal axes (gyroscopes). These enable an INS to continually and accurately calculate its current latitude and longitude (and often velocity). Advantages over other navigation systems are that, once aligned, an INS does not require outside information. An INS
8624-429: The intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Four_Winds&oldid=1200269301 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Classical compass winds Originally conceived as a branch of meteorology , the classical wind rose had only
8736-520: The local Phoenicias (SSE). His highlighting of the Italian "Circius" as a major variant of Thrascias (NNW) could be the first indication of the notorious Mistral wind of the west Mediterranean. Another major change in Timoesthenes is that he shunts Boreas out of the North position and into NNE (replacing Meses) – which will become customary in later authors. Timosthenes is also significant for being perhaps
8848-448: The mainspring, and a special balance designed to compensate for temperature variations. A spring-driven chronometer is set approximately to Greenwich mean time (GMT) and is not reset until the instrument is overhauled and cleaned, usually at three-year intervals. The difference between GMT and chronometer time is carefully determined and applied as a correction to all chronometer readings. Spring-driven chronometers must be wound at about
8960-518: The morning" (engendering a little confusion, as it might be read as they were all easterly winds – although curious that Eurus is not among them). Hesiod refers to other "bad winds", but not by name. The Greek physician Hippocrates (c. 400 BC), in his On Airs, Water and Places , refers to four winds, but designates them not by their Homeric names, but rather from the cardinal direction from which they blow (arctos, anatole, dusis, etc.) He does, however, recognize six geographic points – north, south and
9072-640: The motion of stars, weather, the position of certain wildlife species, or the size of waves to find the path from one island to another. Maritime navigation using scientific instruments such as the mariner's astrolabe first occurred in the Mediterranean during the Middle Ages. Although land astrolabes were invented in the Hellenistic period and existed in classical antiquity and the Islamic Golden Age ,
9184-431: The names of the classical winds, both in Greek and in Latin. The Vatican table lists them as follows: Navigation Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another. The field of navigation includes four general categories: land navigation, marine navigation , aeronautic navigation, and space navigation. It
9296-540: The navigation of spacecraft themselves. This has historically been achieved (during the Apollo program ) via a navigational computer , an Inertial navigation system, and via celestial inputs entered by astronauts which were recorded by sextant and telescope. Space rated navigational computers, like those found on Apollo and later missions, are designed to be hardened against possible data corruption from radiation. Another possibility that has been explored for deep space navigation
9408-561: The navigator Timosthenes of Rhodes (c. 282 BCE) had developed a system of 12 winds by adding four winds to the eight. (Agathemerus is, of course, incorrect – Aristotle had at least ten winds, not eight). Timosthenes's list (according to Agathemerus) was Aparctias (N), Boreas (not Meses, NNE), Caecias (NE), Apeliotes (E), Eurus (SE), "Phoenicias is also called Euronotos" (SSE), Notos (S), "Leuconotos alias Libonotos" (first mention, SSW), Lips (SW), Zephyrus (W), Argestes (NW) and "Thrascias alias Circius" (NNW). In many ways, Timosthenes marks
9520-459: The navigator will have to rely on his skill in the manual and time-tested procedures. Celestial navigation systems are based on observation of the positions of the Sun , Moon , planets and navigational stars . Such systems are in use as well for terrestrial navigating as for interstellar navigating. By knowing which point on the rotating Earth a celestial object is above and measuring its height above
9632-442: The observer lives. Aristotle had aggrandized the wind system beyond Homer to ten winds, but he left it unbalanced. It would be left to subsequent geographers to either add two more winds (to SSW and SSE) to make it into a symmetric 12-wind compass (as Timosthenes would do), or subtract two winds (NNW and NNE) to make it into a symmetric 8-wind compass (as Eratosthenes would do). Theophrastus of Eresos, Aristotle's successor in
9744-405: The observer's horizon, the navigator can determine his distance from that subpoint. A nautical almanac and a marine chronometer are used to compute the subpoint on Earth a celestial body is over, and a sextant is used to measure the body's angular height above the horizon. That height can then be used to compute distance from the subpoint to create a circular line of position. A navigator shoots
9856-503: The oldest record of a sea astrolabe is that of Spanish astronomer Ramon Llull dating from 1295. The perfecting of this navigation instrument is attributed to Portuguese navigators during early Portuguese discoveries in the Age of Discovery . The earliest known description of how to make and use a sea astrolabe comes from Spanish cosmographer Martín Cortés de Albacar 's Arte de Navegar ( The Art of Navigation ) published in 1551, based on
9968-476: The path a radar object should follow on the radar display if the ship stays on its planned course. During the transit, the navigator can check that the ship is on track by checking that the pip lies on the drawn line. Global Navigation Satellite System or GNSS is the term for satellite navigation systems that provide positioning with global coverage. A GNSS allow small electronic receivers to determine their location ( longitude , latitude , and altitude ) within
10080-412: The precise time of a sighting is known. Lacking that, one can use a sextant to take a lunar distance (also called the lunar observation , or "lunar" for short) that, with a nautical almanac , can be used to calculate the time at zero longitude (see Greenwich Mean Time ). Reliable marine chronometers were unavailable until the late 18th century and not affordable until the 19th century. For about
10192-607: The principle of the archipendulum used in constructing the Egyptian pyramids . Open-seas navigation using the astrolabe and the compass started during the Age of Discovery in the 15th century. The Portuguese began systematically exploring the Atlantic coast of Africa from 1418, under the sponsorship of Prince Henry . In 1488 Bartolomeu Dias reached the Indian Ocean by this route. In 1492
10304-402: The qualitative differences in winds – some were humid, others dry, some hot, others cold – and that these qualities depended on where the wind was blowing from. Local directional names were used to refer to the winds, eventually giving the wind itself a proper name , irrespective of the observer's position. This was likely furthered by sailors who, far from landmarks at sea, nonetheless recognized
10416-429: The radar scanner. When a vessel (ship or boat) is within radar range of land or fixed objects (such as special radar aids to navigation and navigation marks) the navigator can take distances and angular bearings to charted objects and use these to establish arcs of position and lines of position on a chart. A fix consisting of only radar information is called a radar fix. Types of radar fixes include "range and bearing to
10528-514: The rear section of the fuselage, whereas most US aircraft enclosed the antenna in a small teardrop-shaped fairing. In navigational applications, RDF signals are provided in the form of radio beacons , the radio version of a lighthouse . The signal is typically a simple AM broadcast of a morse code series of letters, which the RDF can tune in to see if the beacon is "on the air". Most modern detectors can also tune in any commercial radio stations, which
10640-409: The same frequency range, called CHAYKA . LORAN use is in steep decline, with GPS being the primary replacement. However, there are attempts to enhance and re-popularize LORAN. LORAN signals are less susceptible to interference and can penetrate better into foliage and buildings than GPS signals. Radar is an effective aid to navigation because it provides ranges and bearings to objects within range of
10752-412: The same time each day. Quartz crystal marine chronometers have replaced spring-driven chronometers aboard many ships because of their greater accuracy. They are maintained on GMT directly from radio time signals. This eliminates chronometer error and watch error corrections. Should the second hand be in error by a readable amount, it can be reset electrically. The basic element for time generation
10864-400: The screen that is parallel to the ship's course, but offset to the left or right by some distance. This parallel line allows the navigator to maintain a given distance away from hazards . The line on the radar screen is set to a specific distance and angle, then the ship's position relative to the parallel line is observed. This can provide an immediate reference to the navigator as to whether
10976-495: The ship is on or off its intended course for navigation. Other techniques that are less used in general navigation have been developed for special situations. One, known as the "contour method," involves marking a transparent plastic template on the radar screen and moving it to the chart to fix a position. Another special technique, known as the Franklin Continuous Radar Plot Technique, involves drawing
11088-412: The southeast of Greece) and Thrascias ( θρασκίας ) from Thrace (in Aristotle's day, Thrace covered a larger area than today, including the north-northwest of Greece). Finally, Meses ( μέσης ) might simply mean "middle", presumably because it was a half-wind. The implication of reading Thrascias and Meses as half-winds, and the others as principal winds, is that this implies Aristotle's construction
11200-594: The southern tip of South America . Some ships were lost, but the remaining fleet continued across the Pacific making a number of discoveries including Guam and the Philippines. By then, only two galleons were left from the original seven. The Victoria led by Elcano sailed across the Indian Ocean and north along the coast of Africa, to finally arrive in Spain in 1522, three years after its departure. The Trinidad sailed east from
11312-589: The summer and winter risings and settings – using the latter to set the boundaries for the four general winds. The ancient Greek philosopher Aristotle , in his Meteorology (c. 340 BCE), introduced a ten-to-twelve wind system. One reading of his system is that there are eight principal winds : Aparctias (N), Caecias (NE), Apeliotes (E), Eurus (SE), Notos (S), Lips (SW), Zephyrus (W) and Argestes (NW). Aristotle then goes on to add two half-winds , Thrascias (NNW) and Meses (NNE), noting that they "have no contraries". Later, however, Aristotle suggests
11424-407: The sun rises and sets a little further south than in the summer, Consequently, the Homeric system may have had six winds – Boreas (N) and Notos (S) on the meridian axis, and the other four on diagonals: Zephyrus (NW), Eurus (NE), Apeliotes (SE) and Argestes (SW). Strabo, quoting Posidonius notes that Homer sometimes used epithets of qualitative attributes to append ordinal directions to
11536-448: The sun rises in the east, then it heats east winds longer than west winds). With this general classification, Aristotle manages to account for the archaic Greek two-wind system. The exception to this system is Caecias (NE), which Aristotle notes is "half north and half east", and thus neither generally northern nor generally southern. The local Phoenicias (SSE), is also designated as "half south and half east". Aristotle goes on to discuss
11648-809: The table. The practice of navigation usually involves a combination of these different methods. By mental navigation checks, a pilot or a navigator estimates tracks, distances, and altitudes which will then help the pilot avoid gross navigation errors. Piloting (also called pilotage) involves navigating an aircraft by visual reference to landmarks, or a water vessel in restricted waters and fixing its position as precisely as possible at frequent intervals. More so than in other phases of navigation, proper preparation and attention to detail are important. Procedures vary from vessel to vessel, and between military, commercial, and private vessels. As pilotage takes place in shallow waters , it typically involves following courses to ensure sufficient under keel clearance , ensuring
11760-459: The time interval between radio signals received from three or more stations to determine the position of a ship or aircraft. The current version of LORAN in common use is LORAN-C, which operates in the low frequency portion of the EM spectrum from 90 to 110 kHz . Many nations are users of the system, including the United States , Japan , and several European countries. Russia uses a nearly exact system in
11872-425: The twelve winds are: (for the derivation of the Latin etymologies, see the section on Isidore of Seville below). Oddly, Seneca says the meridian line arises from Euronotus (SSE), not Auster (S), and that the "highest" point in the north is Aquilo (NNE), not Septentrio (N). This might imply an awareness of magnetic declination , the difference between the magnetic north ( compass north, in this case Aquilo) and
11984-432: The twelve winds). (Timosthenes's geographic list above is reproduced almost verbatim centuries later, in the 8th-century work of John of Damascus and a Prague manuscript from the early 1300s.) The pseudo-Aristotelean work De Mundo (normally attributed to an anonymous copier of Posidonius , probably written between 50 BCE and 140 CE), the winds are named practically identically to Timosthenes (e.g. Aparctias alone in
12096-415: The winds by their old Greek names (e.g. Zephyrus, Eurus, Boreas), and introduces a few new Latin names – notably, "black Auster", "cold Aquilo" and "frigid Caurus". The Roman writer Seneca , in his Naturales quaestiones (c. 65 CE), mentions the Greek names of some of the major winds, and goes on to note that Roman scholar Varro had said there were twelve winds. As given by Seneca, the Latin names of
12208-447: The winds from the south, known as Notus ( Νότος ). But two more winds – Eurus ( Εὖρος ) from the east and Zephyrus ( Ζέφυρος ) from the west – were added soon enough. The etymology of the names of the four archaic Greek winds is uncertain. Among tentative propositions is that Boreas might come from "boros", an old variant of "oros" ( Greek for "mountains", which were to the north geographically). An alternative hypothesis
12320-404: The year. Using his alphabetical notation, Aristotle notes that during the summer solstice the sun rises at Z (Caecias) and sets at E (Argestes); during the equinox , it rises at B (Apeliotes) and sets at A (Zephyrus), and finally during the winter solstice it rises at Δ (Eurus) and sets at Γ (Lips). So drawn on a compass rose, Aristotle's explanation yields four parallels: Assuming the viewer
12432-490: Was the case with Loran C , its primary use was for ship navigation in coastal waters. Fishing vessels were major post-war users, but it was also used on aircraft, including a very early (1949) application of moving-map displays. The system was deployed in the North Sea and was used by helicopters operating to oil platforms . The OMEGA Navigation System was the first truly global radio navigation system for aircraft, operated by
12544-407: Was unbalanced, but while Timosthenes restored balance by adding two winds to make it a symmetric twelve, Eratosthenes deducted two winds to make it a symmetric eight. It seems that, in practical appeal, Eratosthenes's reduction may have won the day. The famous octagonal " Tower of the Winds " in Athens exhibits only eight winds rather than the ten of Aristotle or the twelve of Timosthenes. The tower
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