Saturday, 25 February 2012

Ancient Maps of the World ( Assignment - 2)

Maps have been an indispensable tool for the purpose of navigation and their necessity was understood long before. The oldest of the maps known date back to the 2300 BCE under the Babylonian Civilisation.
Some of the remarkable ancient maps are given below :

1. Babylonian clay tablets : The oldest known maps are preserved on Babylonian clay tablets from about 2300 B.C. Cartography was considerably advanced in ancient Greece. The concept of a spherical Earth was well known among Greek philosophers by the time of Aristotle (ca. 350 B.C.) and has been accepted by all geographers since.

2. Anaximander's world map :Anaximander(610-546 BCE) created the first world map. It was circular in form and showed the known lands of the world grouped around the Aegean Sea at the center.



3. Eratosthenes : He drew an improved world map, incorporating information from the campaigns of Alexander the Great and his successors. Asia became wider, reflecting the new understanding of the actual size of the continent. Eratosthenes was also the first geographer to incorporate parallels and meridians within his cartographic depictions.


4. Posidonius (150-130 BCE) : He was a Greek Philosopher and a Mathematician. He created his own map based on surveys. Also, he calculated the circumference of the earth which was fairly accurate.


5. Strabo(64 BCE-24 CE) : Strabo is  famous for his 17-volume work Geographica, which presented a descriptive history of people and places from different regions of the world known to his era. Geographica provides a valuable source of information on the ancient world, especially when this information is corroborated by other sources.


6.Pomponius Mela (43 CE) : Pomponius is unique among ancient geographers in that, after dividing the earth into five zones, of which two only were habitable. On the divisions and boundaries of Europe, Asia and Africa, his map is similar to that of Eratosthenes.


7.Marinus of Tyre's world maps : They were the first in the Roman Empire to show China. Around 120 A.D., Marinus wrote that the habitable world was bounded on the west by the Fortunate Islands. The text of his geographical treatise however is lost. He also invented the "equirectangular projection", which is still used in map creation today.



8. Ptolemy(150 CE): Although authentic maps of Ptolemy have never been found, the Geographia(book by Ptolemy) contains thousands of references to various parts of the old world, with coordinates for most, which seem to have influenced early Islamic maps.



# References : http://www.lib.umn.edu/bell , http://academic.emporia.edu/aberjame/map/h_map/h_map.htm , http://s155239215.onlinehome.us/turkic/btn_GeographyMaps/MapsLateAntiquityEn.htm 


# To view the maps in full size, click on the individual images.

Wednesday, 25 January 2012

Navigation Instruments ( Assignment -1 )


1. Odometer : The Ancient Chinese Odometer, also known as Zhi Nan Ju, used a cart with wheels of known circumference. The number of rotations was multiplied by the circumference to find distances between cities.


(a)
 (b)

2. Magnetic Compass(11th Century CE) : (a)Chinese were the first to prepare a magnetic compass using a magnetic spoon on a plate with the handle pointing towards south, in 11th century CE.
(b) Italians started using magnetic compass in around 15th century CE which had a magnetic needle suspended freely and this pointed towards north.


3.Mariner's Astrolabe : The mariner's astrolabe, also called sea astrolabe, was an inclinometer used to determine the latitude of a ship at sea by measuring the sun's noon altitude (declination) or the meridian altitude of a star of known declination.It was widely used around 14th Century CE.

4. Quadrant : A quadrant is an instrument that is used to measure angles up to 90°. It was originally proposed by Ptolemy as a better kind of astrolabe.


5. Gyroscope : A gyroscope is a device for measuring or maintaining orientation, based on the principles of angular momentum. The earliest known gyroscope-like instrument was made by German Johann Bohnenberger in around 1817.



6. Gyro-compass : A gyro-compass­ is a type of non-magnetic compass which is based on a fast-spinning disc and rotation of our planet to automatically find geographical direction.The first gyrocompass was patented in 1885 by Marinus Gerardus van den Bos.


7. Marine Chronometer :  A marine chronometer is a clock that is precise and accurate, it can therefore be used to determine longitude by means of celestial navigation.The Dutch scientist Gemma Frisius was the first to propose the use of a chronometer to determine longitude in 1530.



8. Arabian Kamal : It works on the Polenesian Latitude Hook Method.A rectangular piece of wood is measured to fit the distance of Pole star from the horizon. A knotted string is attached and held with the teeth to ensure fixed distance.



9. Sextant : Its primary use is to determine the angle between a celestial object and the horizon which is known as the altitude. It was made in 18th century by an English instrument maker Jesse Ramsden.



* Click on individual images to see the enlarged version.
** References : www.americanhistory.si.edu , www.list-verse.com , www.earlyoakreproductions.co.uk , www.munterberg.blogspot.com