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
