Navigation: Clocks and Compasses

The history of navigation tools is about clocks, compasses and sextants. Navigating requires knowledge about where you are and where you want to go. Early navigation probably involved short, local trips, where there was no need to know your precise location and only a direction was needed to aim for some destination. This could be accomplished by using landmarks, and also the Sun and the stars.

As voyages became longer, maps and compasses became very useful. The map is a collection of landmark information over a wide range. The compass offers directional headings even when it is difficult to obtain them from Sun or stars. Using an astrolabe to “shoot” the position of stars and the Sun allows a navigator to determine latitude, but determining longitude requires an accurate clock. Maintaining the accuracy of a clock at sea requires tolerance to changing environmental conditions and negates the use of a pendulum.

Compasses began as magnetized needles floating on water, then evolved into dry versions that used a pivot point under the needle. Liquid filled compasses provided dampening against motion. Modern compasses are often dampened by electromagnetic fields. Gyrocompasses use electrically powered gyroscopes to maintain a directional heading and solid state compasses use magnetic field sensors.
Modern GPS systems use atomic clocks to calculate distances and positions.

-3500 – obelisk sundial
-1500 – clepsydra (water drip clock)
-0610 – Anaximander may have created the first map of the world.
0085 – Ptolemy
0200 – compass
0800 – astrolabe
1000 – weight driven clock
1031 – Shen Kua
1269 – Epistola de Magnete
1600 – De Magnete
1656 – pendulum clock
1690 – liquid filled compass – Halley
1761 – Harrison’s clock
1817 – gyroscope
1840 – electric clock
1929 – quartz crystal clock
1949 – atomic clock
1973 – GPS
1991 – MEMS Gyroscopes

SEE ALSO:
Navigation in space

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