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Navigation


The art and science of Navigation.



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Navigation is the science of determination of position and direction on or above the surface of the Earth.


This site explores some of the many tools and navigational aids that have been developed through the ages and some of the explorers and inventors that have contributed to our knowledge about our planet and its moon. This page also touches a little on surveying; which is "the technique and science of accurately determining the terrestrial or three-dimensional space position of points and the distances and angles between them". This page does not attempt to teach you how to navigate.



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Navigation in our daily lives



Simple navigation begins with traveling around in familiar territory. An example would be traveling from your home each day to your school or office. We even have navigational aid to assist us in the form of street names and house and building numbers. As we travel further from home, we may use a map (or on-line services) to plot a course to a destination. This simple form of navigation as known as pilotage. Our highway system has many aids to navigation in the form of signs to aid us. A map is normally used to navigate on land and depicts surface features such as roads, cities, rivers and lakes. A nautical chart is normally used on sea and an aeronautical chart is used in the air. These types of charts depict obstacles that must be avoided and special navigational aids used on the water or in the air. A harbor pilot is someone with extensive knowledge of a body of water that guides a ship through the narrow, shallow and dangerous coastal waters between a harbor and the open sea.


As civilization grew and man began to explore his surrounding and began trading with distant lands, several different types of navigation were developed. The Polynesian Navigators or palu of Micronesia routinely crossed thousands of miles of open ocean, to tiny inhabited islands, using only their own senses and knowledge, passed by oral tradition, from navigator to apprentice. The ancient Norsemen navigated by understanding the migration pattern of birds and whales. The Western Civilization developed a system of navigation based on mathematics, scientific principles and navigational aids such as the map and compass.


Man first navigated by using landmarks, local knowledge and maps. Maps pre-date virtually all other forms of written communication. Some of the earliest known maps are clay tablets from Babylonian (modern Iraq). While the exact age of these clay tables is unknown they are believed to date from between 3,800 B.C. to 2,300 B.C.


Where landmarks are not visible, other techniques must be used. Dead reckoning allows a navigator to deduce position by advancing plotting the position of a vassal on a chart using the course and the distance traveled. The course was determined by Sun, Moon, stars and planets as reference points and later, by the compass. Distance was determined in various ways. On land, paces could be counted or by using an odometer. On water a chip log and sand glass were used to measure the speed the ship was traveling. By knowing the speed and time of travel and after compensating for the effect of winds or currents, an estimated position is derived.


Ptolemy (90-168); a Greek mathematician, geographer, and astronomer assigned coordinates to all the places and geographic features he knew in a grid that spanned the globe (latitude and longitude). The basic technique of the navigator is to derive a position and then plot that position on a chart. This can be accomplished by taking the bearing of two or more known landmarks and plotting the resultant line of position or circle of position on a chart. Where two lines of position intersect a fix is establishes. Positions can be derived from a variety of sources: a) celestial observation, b) terrestrial range (natural or man made) when two charted points are observed to be in line with each other, c) compass bearing to a charted object, d) radar range to a charted object, and e) on certain coastlines, a depth sounding from echo sounder or a hand Sounding line.


Celestial navigation, also known as astronavigation, is a position fixing technique that was devised to help sailors cross the featureless oceans without having to rely on random chance to enable them to strike land. Celestial navigation uses angular measurements (sights) between the horizon and a common celestial object. These measurements are most often taken by using a Sextant; the angle between the horizon and the Sun is most often measured. A chronometer is used to determine the exact time. By knowing the extact time and the hight above the horizon of a celestial object (the sun or a star) a skilled navigator can use the Moon, planets or one of 57 "navigational stars" that are described in nautical almanacs to determine his position.


Today, electronic aids to navigation provide additional aids to the navigator, and in some cases, handle the plotting work as well. Satellite systems such as Global Navigation Satellite System (GNSS) measure the distance to artificial satellites to determine position. One of the most common GNSS system used is the Global Positioning System (GPS) developed in the United States. Increasingly, Electronic Chart Display and Information Systems take these electronic inputs to provide a moving chart showing the travelers location on a electronic chart display. However, it is prudent for the traveler to always know, practice, and have the materials at hand for manual navigation in the event that the electronic aids fail or electrical power is lost.[1]





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Polynesian navigation



The Polynesian navigators of Micronesia routinely crossed thousands of miles of open ocean, to tiny inhabited islands, using only their own senses and knowledge, passed by oral tradition, from navigator to apprentice.


The Micronesian system of navigation is called Etak and is mastered by palu, the navigator. Like European navigation, Micronesian navigation is an integrated system. But unlike a European or western navigation system it does not rely on written materials and instruments. Rather, it combines a vast body of lore and the navigator's own senses. The palu guides his outrigger canoe by the stars at night and with his knowledge of ocean swells and currents during the day and on overcast nights. He keeps the star paths (the rising and setting of the stars) of 32 stars, which form a kind of star compass, in his head at all times. He knows which stars are over which islands during any particular season and time of night. He also recognizes eight "waves", one from each octant (one-eighth) of the compass: Etak assumes that palu, the navigator, is in a canoe that is stationary, and that the islands move on the sea around him. This concept is hard for us to even imagine because we are sure that the canoe is moving. But with the same conviction, the palu is certain that his canoe is stationary and the world is moving around him. In his world view, islands come toward him and move away from him.


The palu must be able to read the stars, the waves, and the clouds, as well as the creatures of the sea. He knows which birds inhabit which islands and he also has been taught that each island has a ring of specific sea creatures around it. When he sets out in his outrigger sailing canoe, it is with this knowledge in his head. Nothing is written down. And all these strands of knowledge interconnect in the palu's mind and allow him to successfully guide his canoe.


The palu is responsible for guiding his people to food and to other island and because of this knowledge, he holds a revered status in his culture, much like a chief. If he cannot guide the fishermen to the fish, his people starve. His knowledge of the sea and of the world was taught to him by his father and he alone can pass this knowledge "the talk of the sea" on to the next generation. [2]


In the Gilbert Islands, celestial maps were re-created on the ceilings of training houses. Carolinian navigators studied sophisticated star compasses constructed on beach mats from coral, coconut leaves, and banana fibers. These short-lived maps and navigational aids were then memorized through verbal exercises, including songs, chants, and dances.


Marshall Islands navigators also relied upon the stars and dead reckoning for long-distance navigation, but for coastal navigating they devised the stick chart. Stick charts aided navigators in sailing near land and in sighting landfalls. Surviving examples are made of coconut palm or pandanus reeds and cowrie shells. The reeds are arranged to replicate patterns of ocean currents and sea swells. Shells represent islands. Three rypes of stick charts were used: rebbelib, a small-scale chart for major island groups; meddo, a larger scale chart displaying one or two island chains in greater detail; and mattang, an abstract chart for instruction. Unlike modern nautical charts, stick charts were consulted prior to a voyage but then were left behind to guide other seafarers. [3]




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Navigation Tool's



This is a list of some of the many tools used for navigation through history. Some of the tools have been replaced by more modern tools but other are still in use. For a more complete list, visit navigational instruments on Wikipedia.



Air Almanac The Air Almanac provides astronomical data for air navigation. The tables in the Air Almanac allow the navigator to convert astronomical sightings to a position given in degrees of Longitude and Latitude.
Artificial horizon Artificial horizon is an instrument that displays a line that lies within the horizontal plane and is not affected by the pitching, rolling and banking movements of an aircraft or sailing vessel. An artificial horizon can also be used when the true horizon is not visible due to fog, hills, trees or any obstruction. Lewis and Clark carried an "Artificial Horizon" that contained a pool of mercury or water covered by a sheet of glass. Since liquid will lie perfectly flat they could use the surface to find the true horizon. See Attitude indicator.
Astrolabe The astrolabe is a historical astronomical instrument used by astronomers, navigators and astrologers before the invention of the sextant in the 18th century. Its many uses included locating and predicting the positions of the Sun, Moon, planets and stars; determining local time given local longitude and vice-versa, surveying, and triangulation.
Chip log A chip log consists of a piece of wood, most often cut in the shape of a quarter circle, or "quadrangle", with a length of line (rope) attached to a spool and a knot tied in the line every 47 feet and 3 inches. The chip log would be placed into the water off the stern of the ship, the line would be allowed to be "paid out" (run out), and the number of knots paid out in 30 seconds counted. A sandglass was used to count the 30 seconds. A ship traveling at a speed of 1 knot in 30 seconds would travel 1 nautical mile per hour. This is the reason that ship measure their speed in knots.
Chronometer A chronometer is a very accurate, portable timekeeper device precise enough to be used as a time standard. John Harrison developed the first successful chronometers, which for the first time allowed a navigator to accurately assess his ship's position in longitude
Compass A compass consists of a magnetized pointer that is free to align itself accurately with Earth's magnetic field. An early form of the compass was invented in China in about 271 AD. The familiar mariner's compass was invented in Europe around 1300. The cardinal points are normally marked on the compass and are north, south, east and west. A compass can also be marked off in degrees, with north at 0°, east at 90°, south at 180° and west being at 270° and on to 360° at due north once again. The compass greatly improved maritime trade by making travel safer and more efficient. When the compass is used in conjunction with a chronometer and a sextant it can provide a very accurate means of navigation,
Dividers A divider is a tool used in navigation for measuring distances on the chart. A divider is usually made of metal, and consists of two parts connected by a hinge which can be adjusted. Each part of the compass ends with a spike. The separation between the two legs can be set using the scale located on the chart (map). The navigator then counts how many times the divider fits between two points on the chart. Also see Compass (drafting).
Gyrocompass The gyrocompass or gyroscopic compass was introduced in 1907 by inventor Elmer A. Sperry. The movement of the compass depends on a gyroscope, a free-spinning disk mounted on a base, so that the disk remains in a fixed position no matter what direction the base is moved. The gyroscope is aligned on a north-south axis, and the compass points to true north rather than magnetic north. This made the compass a more reliable navigational device, and Sperry's gyroscopic compass was adopted by the U.S. Navy in 1911, playing a major role in the First World War.[4]
Gyroscope A Gyroscope is a device with a rapidly spinning wheel on an axle that tends to resist changes to its orientation due to the angular momentum of the wheel. The gyroscope is a device for measuring or maintaining orientation, and is based on the principle of conservation of angular momentum. A gyroscope is the heart of the gyrocompass.
Octant The term "octant" means 1/8 of a circle, or 45 degrees. An Octant is an instrument based on the same principle as the sextant but employing only a 45° angle.
Parallel rulers A Parallel ruler consists of two straight edges joined by two arms which allow them to move closer or further away while always remaining parallel to each other. Parallel rules are used by the navigator to find bearing and direction and to draw parallel lines on a chart.
Sandglass A sandglass is a device for measuring time, (See Hourglass.) The invention of the chronometer made the sandglass obsolete for navigational purposes.
Sextant A sextant is used to measure the angle of elevation of a celestial object above the horizon. The sextant is used to determine latitude. This is done by measuring the angle between the horizon and the sun when the sun is at its highest point, then using tables to determine which line of latitude the sun should be above on that particular day.
Sounding line A sounding line or lead line is a length of thin rope with a weight at one end and with knots at a fixed interval along its length and is used to measure the depth of the water. The knots where normally tied every 1.8 meters (2 yards) or at 1 fathom intervals. The bottom of the weight was often hollow so that when the weight hit the sea floor a sample of the sediment was returned to the ship when the sounding line was hauled back aboard ship. When sounding lines were in common use, the nautical charts contained a description of the type of sediment at a particular death. This help to determine the exact position of a ship when it was close to shore.
Theodolite A Theodolite is an instrument for measuring both horizontal and vertical angles, as used in triangulation networks. It is a key tool in surveying, engineering work and cartography, but theodolites have been adapted for other specialized purposes in fields like meteorology and rocket launch technology. A theodolite consists of a telescope mounted movably within two perpendicular axes, the horizontal or trunnion axis, and the vertical axis. When the telescope is pointed at a desired object, the angle of each of these axes can be measured with great precision, typically on the scale of arc-seconds (Also see Minute of arc; Cartography). Jesse Ramsden provided a new large theodolite, known as the Ramsden theodolite, for General William Roy, of the Royal Engineers, which was used for a new survey of the distance between Greenwich, London and Paris in 1791. This work provided the basis for the subsequent Ordnance Survey of Britain. William Roy received the Copley Medal in 1795 for his survey of the United Kingdom and Ramsden, was elected to the Royal Society in 1786 for his important contributions to fields such as optics (the Ramsden eyepiece and electrostatics.

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Aids to Navigation


Today we have many aids to navigation. The type of navigational aid needed depends on whether you are on land, the water or in the air. Listed below are some of the many navigational aids in use today and a few historical ones.



   Index of Aids to Navigation.


Aids to Navigation - Land

  • Road signs - there are many different type of signs located along our roads that aid us in our trips to new places. Below are a few of the more familiar.
    • Cardinal Direction Auxiliaries - normally located on highways that connect distant cities and town. These signs indicate the direction of travel, North, South, East or West.
    • Destination, Distance, and General Guide Signs - these signs tell us what direction a location is (to the right, left or straight ahead) and how far we are from a place, normally the next city or town.
    • Milestones - series of numbered markers placed along a road at regular intervals allow the traveler to know that the proper path is being followed and to indicate distance traveled, or the remaining distance to the desired destination. Today Milestone or markers are made of metal, but were originally stone (granite or marble or whatever local stone was available) obelisks. Milestones were used by the Roman Empire road builders on the Roman road network.
    • Junction Signs - Indicates that two or more highways are crossing.
    • Route Markers - Indicates the name or the number of the highway, examples are US 1 or Interstate 20.
    • Street numbers (address) - the number assigned to the specific location such as a house of building. At a given location, there may be secondary address numbers such as an apartment number, suite, units or slip.
    • Street signs - give the name of the street. These signs are normally located at the intersection of two or more streets.
  • Trail Signs - the type of signs used to mark trails depends on the purpose (temporary or permanent) and the type of material (wood, grass, stones) available along the route of the trail.
    • Cairns (Stone Signs) - Cairns are stones placed along trails that cross rocky areas where there are no trees or plants to mark the trail. A cairns may be stones stacked on top of another or laid out as a arrow pointing in the direction of travel.
    • Grass and Twig Signs - These types of trail signs are left along a route by someone scouting ahead of a group and normally are less permanent than a blaze or a stone cairns.
    • Blazes - these are marks normally made on a tree, but can also be left on large rocks when there are no trees. Originally, blazes were made by removing a section of bark from a tree with a knife or axe. Today, blazes are made using paint.

  • Benchmarks, survey marker and Geodetic control points are permanently affixed objects at various locations all over the United States to enable land surveying, civil engineering and mapping to be done efficiently. These objects are usually metal disks, but can be any other object that serves as a control point. The British mainland, and many of its off shore islands, have a abundance of small, roughly 4 foot high concrete called Trig Pillars. There are two general types of these control points; vertical control points and horizontal control points.
    • Vertical control points are a series of points on which precise heights, or elevations, have been established. Vertical control stations are typically called benchmarks. This type of control point is usually, but not always, a small brass or aluminum disk, concrete post, iron pin, or bolt, (among other things), that is permanently attached to a stable foundation.
    • A horizontal control point is for horizontal control and provide positional information (latitude and longitude). There are several names for horizontal control points, triangulation, traverse stations, trilateration stations, GPS stations, and intersection stations, depending on which kind of horizontal control system was used in establishing them and the amount of precision they represent. This type of control point can be a small brass or aluminum disk, concrete post, iron pin, or bolt, (similar to the vertical control points) but also be water towers, church spires, radio towers and mountain tops or any type of object that can be identified from a distance.
  • The British mainland, and many of its off shore islands, have a abundance of small, roughly 4 foot high concrete called Trig Pillars (horizontal control points). Each and a unique number, and were used to map Great Britain by 'triangulation' using a theodolite.

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Aids to Navigation - Water

  • Channel markers - markers placed in harbors, lakes or other waterways to aid in navigation.
    • Buoy - A buoy is a floating device that can have many different purposes, which determines whether the buoy is anchored (stationary) or allowed to drift. Buoys used to mark channels are painted red and green and are always anchored. Generally speaking, green channel markers are kept to the RIGHT when leaving a harbor and red channel markers are kept to the RIGHT when returning to harbor, thus coining the phrase, "Red, Right, Returning". A buoy may also have a light to mark the position of the channel at night or have a bell to indicate the position of the buoy in bad weather.
    • Preferred channel markers - are a combination of red and green markers that indicate the preferred channel. Years ago, this marker was known as a junction marker. The preferred or better channel is usually marked by having the top color of the marker indicate the way it should be treated.
    • Range Day markers - are found in pairs with one higher than the other. Range markers indicate the center line of a channel by having them lined up as you pass through the channel. They will have vertical colored panels to assist in lining them up.
  • Decca Navigator System was a hyperbolic low frequency radio navigation system (also known as multilateration) that was first deployed during World War II.
  • Lighthouses are a building or framework sending out light from a system of lamps and lenses that are used to mark dangerous coastlines, hazardous shoals away from the coast, and safe entries to harbors. Since the higher the light is above the surface of the water, the further out to sea it is visible, lighthouses are normally very tall structures or are build high up on a cliff. Augustin-Jean Fresnel developed a design using lenses of large aperture and short focal length that concentrated the light and made it visible at a greater distance. The first Fresnel lens was used in 1822 in a lighthouse on the Gironde River in France, and could be seen from more than 20 miles out. The lens of the lighthouse would rotate so that rather than seeing a continuous weak light, a brighter light would be seen during a short time interval. Each lighthouse has a characteristic light pattern so lighthouses could be distinguished from each other. Lighthouses where are also painted with distinctive patterns so the navigator could distinguish which lighthouse was in sight during the day.
  • LORAN is an acronym for LOng RAnge Navigation. LORAN is a terrestrial based radio navigation system using low frequency radio transmitters that use the time interval between radio signals received from three or more stations to determine the position of a ship or aircraft. With the development of GPS, the use of LORAN is in steep decline.

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Aids to Navigation - Air

  • Attitude indicator or artificial horizon indicates an aircraft's orientation relative to the ground. It indicates pitch (fore and aft tilt) and roll (side to side tilt).
  • Automatic Direction Finding (ADF) uses a series of non-directional beacons (NDF) located at a ground station and its associated automatic direction finding (ADF) equipment located in an aircraft. ADF is primarily a short distance navigational aid. The ground station (NDB) radiates a signal in all directions around the transmitter, and the aircraft receiver (ADF), when tuned to this signal, determines the direction from which the signal is being radiated. By following the direction indicated by the ADF instrument the aircraft will fly over the NDB.
  • Heading indicator (HI), or the directional gyro, informs the pilot of his heading, or direction.
  • OMEGA Navigation system was the first truly global radio navigation system for aircraft, operated by the United States in cooperation with six partner nations. Each Omega station transmitted a very low frequency signal (VLF)which consisted of a pattern of four tones unique to the station that was repeated every ten seconds. Because of this and radio-navigation principles, an accurate fix of the receiver's position could be calculated. OMEGA employed hyperbolic radio-navigation techniques and the chain of OMEGA stations operated in the VLF portion of the spectrum between 10 to 14 kHz.
  • Instrument Landing System (ILS) is a system which provides precise guidance to an aircraft approaching a runway.
  • VHF Omni Directional Range (VOR), is a type of radio navigation system for aircraft. VORs broadcast a VHF radio composite signal including the identification code (in Morse or voice), and data that allows the airborne receiving equipment to derive the magnetic bearing from the station to the aircraft. This line of position is called the "radial". The intersection of two radials from different VOR stations on a chart allows for a "fix" or specific position of the aircraft to be determined.

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Other Aids to Navigation

  • Global Navigation Satellite System (GNSS) is the standard generic term for satellite navigation systems that provide autonomous geospatial positioning anywhere on the Earth.
  • Global Positioning System (GPS) is a Global Navigation Satellite System (GNSS) consisting of more than two dozen GPS satellites located in medium Earth orbit (MEO). The GPS satellites transmit a signal that allows a GPS receiver to determine the receiver's location, speed and direction. A GPS receiver calculates its position by measuring the distance between itself and three or more GPS satellites.
  • Radio direction finder is a device for finding the direction to a radio source. Because radio waves can travel very long distances "over the horizon", it makes a particularly good navigation system for ships and aircraft that are at a distance from land.
  • GLONASS is a radio satellite navigation system created by the former Soviet Union, now Russia. It is the Russian counterpart to the United States GPS system


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Maps


   Index of Maps.


The study and practice of making maps or globes is known asCartography (in Greek chartis = map and graphein = write). Maps were traditionally made using pen and paper, and then with the invention of the airplane and the camera, a process called Photoimage mapping was developed. With the advent and spread of computers, cartography has been revolutionized. Today most commercial-quality maps are made with map-making software that falls into one of three main types; Computer-aided design (CAD), Geographic information system (GIS), and specialized map illustration software.


The cartographic process rests on the premise that the world is measurable and that we can make reliable representations or models of that reality. Mapmaking involves advanced skills and aptitudes in the use of symbols to represent certain geographic and physical phenomena. The Cartographer must be able to visualize the world in an abstract and scaled-down form.


Maps function as visualization tools for spatial data that is acquired from measurement and can be stored in various forms and then is used for a variety of purposes. Current trends in this field are moving away from analog methods of mapmaking and toward the creation of increasingly dynamic, interactive maps that can be manipulated digitally.


Several different map making traditions evolved between the 7th century and the 15th century. Most notably in the three major geographical areas of: Europe, the Middle East and Asia, each with its own traditions of expressing spatial concepts in graphic form.


The shape of the Earth is very close to an oblate spheroid (a rounded shape with a bulge around the equator) and is most easy represented as a globe. Flat maps can be more useful than globes in many situations. A map is more compact and easier to store, maps can more readily accommodate an enormous range of scales, they can facilitate measuring properties of the terrain, they are viewed easily on a flat computer displays, and they are cheaper to produce and transport. Cartographers use a technique called "projection" to show the round earth on a flat map.


A map projection is any method used in cartography (mapmaking) to represent the three-dimensional curved surface of the earth or other body on a two-dimensional plane. The term "projection" here refers to any function defined on the earth's surface and with values on the plane, and not necessarily a geometric projection.


Types of cartographical projects of the world:[5]


  • Alberts Conic Equal-Area is a good format for mapping the mid-latitudes such as the United States. Lines of latitude on this type of project will appear to be curved.
  • Azimuthal Equidistant is a project in which all distances measured from the center of the map along any longitudinal line are accurate. A useful application for this type of projection is a Polar Projection.
  • Bottomley projection is an equal-area map projection. The lines of latitude are concentric elliptical arcs of constant eccentricity, centered on the North Pole. On the central meridian, shapes are not distorted, but elsewhere they are.
  • Eckert Equal-Area projection was developed by German educator Max Eckert. Line poles for this project are half the length of the Equator. Polar regions are less compressed than on elliptical projections, low-latitude landmasses are elongated.
  • Gnomonic projections displays all great circles as straight lines. On a Gnomonic projection the shortest route between two locations in reality corresponds to that on the map (see Great circle route). This is achieved by projecting, with respect to the center of the Earth (hence perpendicular to the surface), the Earth's surface onto a tangent plane. The least distortion occurs at the tangent point. Less than half of the sphere can be projected onto a finite map. Also see Map projection - Gnomonic
  • Interrupted Goode Homolasine - To minimize distortion of scale and shape, the Interrupted Goode Homolasine project interrupts the globe, its equal-area quality makes it suitable for mapping distributions of various kinds of information.
  • Lambert Azimuthal Equal-Area - Distance from the tangent point on the map is proportional to straight-line distance through the earth. Distortion away from the center makes this projection a poor choice for world maps but useful for fairly circular regions, such as the moon or the polar regions.
  • Mercator projection developed by Flemish geographer and cartographer Gerardus Mercator, in 1569. The Mercator projection is a cylindrical map projection that became the standard map projection for nautical purposes because of its ability to represent lines of constant true bearing or true course, as straight line segments.
  • Moltweide - In 1805 Carl B. Molloweide, a German mathematician, devised this elliptical equal-area projection that represents relative sizes accurately but distorts shape edges. Many thematic maps in Atlases use the Mollweide projection.
  • Oblique Flat Polar Quartic projection, first presented in 1949, produces axes oblique to each other. Unlike many conventional world projections that display the two Poles as lines, Poles appear as points with less distortion.
  • Orthographic projection is designed to show earth as seen from a distant point in space. The Orthographic project is usually used to show the hemisphere. Landmasses along the edge are distorted in this type of project.
  • Stereographic - is a mapping that projects each point on a sphere onto a tangent plane along a straight line from the antipode of the point of tangency. Like the orthographic, this projection was used in the second century B.C. by Hipparchus. It was one of the first to show the world as round. All points lie in true direction from the center, but outer areas are stretched.


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Surveying the World[7]

The foundation for our modern systems of navigation and cartography were developed by Ptolemy; a Greek mathematician, geographer, astronomer, and astrologer. He assigned coordinates to all the places and geographic features he knew, in a grid that spanned the globe in the second century. After the fall of the Roman Empire the scientific advances represented by Ptolemy were lost to Europe and where replaced by Christian doctrine. Most mapmakers discarded the spherical Earth for a flat, circular one to produce world maps known as "Mappa mundi". These pictorial maps, centered on the holy city of Jerusalem, portrayed Old Testament and classical historical and geographical lore. Alongside these religious inspired maps practical and functional maps existed to aid travelers and seafarers. These itinerary maps and portolan charts were drawn to scale and provided detailed information on distances and directions.


After the conquest of Egypt by Arab armies in the seventh century (reference the Muslim conquest of Egypt) Greek scientific works, including Ptolemy's Alamgest and Geography, were translated into Arabic. In about 1400 a Byzantine copy of these works was translated into Latin and carried to Italy. This, combined with the invention of the printing press by Johannes Gutenberg, sparked a revival in scientific cartography that spread throughout Europe, and eventually around the world. The voyages of discovery by Europeans spurred European mapmaking and map use. Protolan charts expanded beyond the Mediterranean. In the first half of the 16th century, mapmakers in Vienna and Germany (Nurnberg, Heidelberg and Freiberg) began elementary land surveys of northern Italy and central Germany.


During the 17th century, the Netherlands produced some of the worlds greatest mapmaker. Gerardus Mercator developed a new world projection which still is used for navigation (see Mercator projection) today. Other prominent Dutch Cartographers are, Abraham Ortelius, Jodocus Hondius, Willem Janszoon Blaeu, and his son Joan Blaeu. They devised and introduced the atlas as a physical object and popularized printed sea charts and wall maps.


In the late 17th and 18th centuries, the French Royal Academy of Sciences sponsored measurements of an "arc of meridian". This led to a more accurate determination of the dimensions and shape of the Earth, perfected methods for determining longitude, and initiated the triangulation of France (Histoire de la triangulation en France). The French were the first to conduct an official national land survey based on triangulation and to establish an official hydrographic office for marine surveying, the Depot des Cartes et Plans de la Marine. The resulting Carte Giomitrique de fa France, begun in 1747, was completed 40 years later. It consisted of 182 sheets, with maps of uniform size and scale, 1:86,400.


Inspired by the French, other countries began large scale topographic surveys. In 1770 Belgium began the national land survey. Great Britain established its Ordnance Survey in 1784, and the British Hydrographic Office in 1795. By the late 19th century, official large-scale topographic map series had been prepared for most of Europe. The United States began geodetic surveys later than most of the world's major countries. The agency known as the Survey of the Coast began work in 1807. The agency was later identified as the Coast Survey in 1836, renamed the Coast and Geodetic Survey in 1878 and since about 1970 the National Geodetic Survey, presently an office in the National Ocean Service a division of the National Oceanic & Atmospheric Administration (NOAA). For more information on NOAA and the National Ocean Service, visit the NOAA home page, click here or for information about the history of NOAA, click here).


British surveyors began the Great Trigonometrical Survey of India on April 10, 1802. When the survey was completed near the end of the 19th century, India was probably the best-mapped region in the world. Radhanath Sikdar, an Indian mathematician and surveyor from Bengal, was the first to identify Mount Everest as the world's highest peak in 1852, using trigonometric calculations based on measurements of "Peak XV" (as it was then known) made with theodolites from 150 miles (240 km) away in India. Measurement could not be made from closer due to a lack of access to Nepal.


The Dutch Topographic Service began mapping in the Netherlands East Indies (Indonesia) in the 1860s. The first official topographic maps of Cambodia, Laos, and Vietnam were prepared by the French Army's Topographic Bureau in 1886. Similarly, the Japanese Army mapped Manchuria in the 1930s.


Thematic maps, also called statistical maps, are special purpose maps that illustrate a particular subject or theme. Thematic maps were introduced in the 1600s, but their value was not recognized until the 19th century. With the emergence of the natural sciences such as geology and meteorology, and the collection of census data, beginning in the United States in 1790 and Great Britain in 1801, the necessary data was collected to produce many types of Thematic maps. The adaptation of lithography to map printing during the first decade of the 19th century, and the introduction of color printing in the 1840s, provided an inexpensive and versatile method for reproducing the tones, shadings, and colors required to illustrate the qualitative and quantitative data portrayed by thematic maps.


Mapmaking became more specialized, efficient and accurate with the development of Aerial Photography during World War I, and the related deployment in the 1920s of instruments of photogrammetry - the science of making reliable measurements by the use of photographs. These plotting instruments reduced the need for ground surveys and helped translate the information on aerial photographs into detailed maps.


Military units mapped much of the world during World War II and the subsequent Cold War with the aid of aerial photographic techniques, improved plotting instruments, and high-speed, multi-color offset printing presses. The last quarter of the 20th century has been characterized by continuous and rapid innovation in cartography. Remote sensing satellites, global positioning systems (GPS), high speed computers and lunar and extraterrestrial space probes record mappable data at a daily rate unimaginable before.


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Types of Maps

There are many types of maps in production and use today. Listed below is a sample of some of them.


  • Aeronautical chart is a map designed to assist in navigation of aircraft. Using these charts and other tools pilots are able to determine their position, best route to a destination, navigation aids along the way, alternative landing areas in case of an in-flight emergency, and other useful information such as important radio frequencies and airspace boundaries.
  • Geologic maps show subsurface geological features. Type of Geologic maps are:
    • Oil and gas investigation maps and charts
    • Geologic quadrangle maps - bedrock, sub-surface, or engineering geology
    • Coal investigation maps
  • Hydrologic Maps - show hydrologic features such as lakes, rivers and streams. They can also show information about water located below the surface. They may include the volume of water in storage (saturated thickness), elevation of the water table, land surface elevation and irrigation system location.
  • Linguistic map - show the geographic distribution of the speakers of a language.
  • Nautical chart - is a graphic representation of a maritime area and adjacent coastal regions
  • Pictorial map - Pictorial maps are a category of maps that also loosely includes illustrated maps, panoramic maps, bird's-eye view maps and Geopictorial maps.
  • Political map - shows political boundaries such as countries and states.
  • Road maps - A map of roads, and possibly other features, to aid in navigation
  • Thematic map - also called a statistical or special purpose map - displays the spatial pattern of a theme or series of attributes. Thematic maps may include:
    • Early Indian Tribes
    • Potential Natural Vegetation
  • Topographic maps show both natural and man-made features and quantitative representation of relief, usually using contour lines.
  • Topographic-bathymetric maps - show elevations above and below the water surface
  • Trail maps provide information useful to hikers and campers as they travel cross country along the many designated hiking trails. Some examples of trail maps are:
  • Weather map - provides a view of weather elements over a specified geographical area at a specified time.
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Other Maps Facts and Trivia

  • The most common cartographic convention is that North is at the top of a map. This is far from universal, however.
  • Portolan charts are oriented to the shores they describe.
  • Medieval European T and O maps such as the Hereford Mappa Mundi were centered on Jerusalem with east at the top. Indeed, prior to the reintroduction of Ptolemy's Geography to Europe around 1400, there was no single convention in the West.
  • In pointing out the arbitrariness of the "north is up" convention, some southern-hemisphere publishers (notably Australians) have published "upside-down" maps of the world.
  • Route and channel maps have traditionally been oriented to the road or waterway they describe.
  • Maps from non-Western traditions are oriented in a variety of ways.
  • Old maps of Edo show the Japanese imperial palace as the "top", but also at the centre, of the map. Labels on the map are oriented in such a way that you cannot read them properly unless you put the imperial palace above your head.
  • Buckminster Fuller's Dymaxion maps are based on a projection of the Earth's sphere onto an icosahedron. The resulting triangular pieces may be arranged in any order or orientation.
  • Polar maps of the Arctic or Antarctic regions are conventionally centered on the pole, making "north is up" meaningless.
  • Azimuthal or Gnomonic projections are often used in planning air routes, centered on specific origin points.
  • Richard Edes Harrison produced a striking series of maps during and after World War II for Fortune magazine. These used "bird's eye" projections to emphasize globally strategic "fronts" in the air age, pointing out proximities and barriers not as apparent on a conventional rectangular projection of the world.
  • Many but not all maps are drawn to a scale. An example of a map not drawn to scale is the London Underground map, which best fulfils its purpose by being less physically accurate and more visually communicative to the hurried glance of the commuter. Also see Tube Maps.
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Navigation Games



Games Using GPS Systems

Geocaching

Geocaching (pronounced "geocashing") is a game in which players hide objects that other players use Global Positioning System (GPS) receivers to find. Traditionally, the hidden object is a waterproof container with a log book and various inexpensive prizes. Finders are encouraged to take something, leave something, and sign the log.



Shutterspot

Shutterspot is a game in which some players take photographs and other players are challenged to find the exact spot where the photographer stood when the camera shutter clicked. That's the "Shutterspot".



Benchmark Hunting

Benchmark Hunting is similar to Geocaching but rather than searching for cashes hidden by others you search for Geodetic control points called benchmarks. Geodetic control points are permanently affixed objects at various locations all over the United States to enable land surveying, civil engineering and mapping to be done efficiently. These objects are usually metal disks, but can be any other object such as radio towers, water towers, church spires and mountain tops can all serve as a control point.



For more information on Benchmark Hunting, visit Papa Bear's Benchmark Hunting Site

Benchmark Hunting Wiki

 Waymarking

Waymark is similar to Geocaching but rather than searching for cashes hidden by others you search everyday object that have been waymarked by others. There are waymarking categories different type of objects to find. An example is the category of "City and Town Halls". A City Hall is entered in to the database and then others visit, or if you are the first to visit, then you can enter the City Hall as a new waymark. It is similar to a scavenger hunt.





Games Using Map and Compass

Route Orienteering

In Route Orienteering you follow a route using a map and a compass. The rout is laid out by the organizers of the event. Parts of the rout may be along roads and part may be cross-country. The route is indicated on a master map located at the routs starting point; you copy off the route on your own map and follow the rout using your map and compass. There are a number of stations not marked on the map located at various points along the rout. The object is to mark the location of each of these stations on your map. The winner of the event is the participant who has found the most stations and has indicated them correctly on his map, Speed is not counted, but a time limit should be set.


Project Orienteering

Project Orienteering tests your map-and-compass skills and your other outdoor skills as well. As you follow; the route, laid out as for route orienteering, you arrive at various stations where signs tell you what to do. Projects may be anything from collecting from a number of different leaves or boiling a quart of water to deciphering a Morse code message or chopping through a log. The separate scores you receive from the judges located at the different project stations are added to your orienteering score.


Point Orienteering

In point orienteering you are not given a definite route but only the location of a number of points which you have to reach one after the other in numerical order. You select your own route from one point to the next, and decide on the quickest and easiest way of getting there. The organizers of the event may show you all the points on a master map so that you'll know all of them before setting out, but it is more common to have each point revealed one at a time on a marker at each station.


Score Orienteering

Score orienteering is a variation of point orienteering. The map is put up at the starting point with a number of stations marked on it. Next to each station mark is a figure which indicates the score you'll receive if you succeed in getting to that station. The nearby; easily reached stations have low point values; the faraway, tough to reach station have a higher point value. You have to layout your own route, planning it in such a way that you'll get the biggest possible score within the specified time limit.


Tracking

Tracking involves laying a trail or following a trail laid by others. A trail is a serial of trail signs, namely directions, laid on the ground.




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Navigators/Explorers/Surveyors


This is a list of some of the many navigators, explorers, cartographers and surveyors that helped to map our world. For a more complete list, visit list of explorers and the list of cartographers on Wikipedia. Also see Distinguished Women of Past and Present for information on women explores.






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References

  1. ^ Wikipedia,  Navigation. [Online] http://en.wikipedia.org/wiki/Navigation
  2. ^ Dickinson, Rachel  Tools of Navigation. White River Junction, VT: Nomand Press, ©2005 pp 25-26
  3. ^ Ralph E. Ehrenberg  Mapping the World; An Illustrated History of Cartography.  National Geographic, Washington DC ©2006 p 23
  4. ^ Canadian Geographic  Finding Our Way. [Online] http://www.canadiangeographic.ca/Magazine/ND01/findingourway.asp
  5. ^ National Geographic Atlas of the World seventh edition. Washington DC; National Geographic, ©2006 plate 3.
  6. ^ Ambrose, Stephen E.  Undaunted Courage.  Simon & Schuster, ©1996
  7. ^ Ralph E. Ehrenberg  Mapping the World; An Illustrated History of Cartography.  Washington DC; National Geographic, ©2006 pp 10-13.

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