the compass moves. If it does, it means that the area or rock the compass was previously at is causing interference and should be avoided. See also Absolute bearing Aircraft compass turns Astrocompass Binnacle Boxing the compass Brunton compass Coordinates Direction determination Earth inductor compass Fibre optic gyrocompass Fluxgate compass Geological compass Gyrocompass Hand compass Inertial navigation system Magnetic declination Magnetic deviation Magnetic dip Magnetometer MEMS magnetic field sensor Marching line Pelorus (instrument) Radio compass Radio direction finder Relative bearing Solar compass South-pointing chariot Wrist compass Citations Cited sources Further reading Admiralty, Great Britain (1915) Admiralty manual of navigation, 1914, Chapter XXV: "The Magnetic Compass (continued): the analysis and correction of the deviation", London : HMSO, 525 p. Aczel, Amir D. (2001) The Riddle of the Compass: The Invention that Changed the World, 1st Ed., New York : Harcourt, Gies, Frances and Gies, Joseph (1994) Cathedral, Forge, and Waterwheel: Technology and Invention in the Middle Age, New York : HarperCollins, Gubbins, David, Encyclopedia of Geomagnetism and Paleomagnetism, Springer Press (2007), Gurney, Alan (2004) Compass: A Story of Exploration and Innovation, London : Norton, Ludwig, Karl-Heinz and Schmidtchen, Volker (1997) Metalle und Macht: 1000 bis 1600, Propyläen Technikgeschichte, Berlin: Propyläen Verlag, Ma, Huan (1997) Ying-yai sheng-lan [The overall survey of the ocean's shores (1433)], Feng, Ch'eng-chün (ed.) and Mills, J.V.G. (transl.), Bangkok : White Lotus Press, Seidman, David, and Cleveland, Paul, The Essential Wilderness Navigator, Ragged Mountain Press (2001), Williams, J.E.D. (1992) From Sails to Satellites: the origin and development of navigational science, Oxford University Press, Wright, Monte Duane (1972) Most Probable Position: A History of Aerial Navigation to 1941, The University Press of Kansas, Zhou, Daguan (2007) The customs of Cambodia, translated into English from the French version by Paul Pelliot of Zhou's Chinese original by J. Gilman d'Arcy Paul, Phnom Penh : Indochina Books, prev publ. by Bangkok : Siam Society (1993), External links Handbook of Magnetic Compass Adjustment Paul J. Gans, The Medieval Technology Pages: Compass Evening Lecture To The British Association At The Southampton Meeting on Friday, August 25, 1882. Refers to compass correction by Fourier series. Chinese inventions Magnetic devices Navigational equipment Ancient inventions