hat
Kòm gen lontan kòm se 15zyèm syèk la, aux te note ke zegwi nan yon bòn teknik pa montre byen vre latè a nò. Columbus, paegzanp te o kouran de sa sou voyages li atravè Atlantic a nan 1490s la. Okontrè, zegwi a ap fè yon ang ak tout bon nan nò, ak sa ang varies toupatou sou sifas tè a. Sa vle di ke gen yon diferan varyasyon teknik pou divès kote sou latè. Varyasyon sa yo te envestige yon gran 17th syèk vwayaj ke gwo doktè legliz di Kris la ak astwonòm Edmond Halley. Li te panse nan moman sa a ki Lonjitid de yon batiman an te kapab jwenn pa varyasyon sèk la, men sa te pwouve pou fè adiltè.
eng
As long ago as the 15th century, mariners noticed that the needle of a magnetic compass does not point accurately to Earth's true north. Columbus, for instance was aware of this on his voyages across the Atlantic in the 1490s. Instead, the needle makes an angle with true north, and that angle varies from place to place on the Earth's surface. This means that there is a different magnetic variation for different places on Earth. These variations were investigated on a famous 17th century voyage by the great scientist and astronomer Edmond Halley. It was thought at this time that the longitude of a ship could be found by the compass variation, but this proved to be untrue.