Kamal (astronomy)

from Wikipedia, the free encyclopedia

A Kamal is an astronomical navigation device used to determine the angular height of a celestial object and thereby the geographical latitude of a place.

Use of the Kamal to determine the angular height of the North Star . Since this star is now almost exactly at the celestial north pole , the elevation angle corresponds to the geographical latitude of the observer.
Side view of the use of the Kamal.

The kamal was invented by Arab sailors in the 9th century and used by the Chinese, Indians and Arabs mainly in the 18th and 19th centuries. On the coast of the Hadramaut in what is now Yemen , sailors used a kamal for navigation until the first half of the 20th century. Since the pilot from Vasco da Gama from Malindi , Ahmad Ibn Majid, used a Kamal, some Portuguese sailors also took over the Kamal. However, they changed the spacing of the nodes to determine the degree.

A kamal is a small board (about 1 × 2 inches) with a hole in the middle through which a string is passed. There are knots on this string that indicate a position of a city or a landmark along the route. The helmsman holds the end of the line with his teeth and shifts the position of the kamal at eye level until the lower edge is on the horizon and the upper edge touches the North Star . Then he pulls the string through the central opening of the kamal. The proximity of a node in the opening then indicates the latitude of the location on the coast to the ship.

See also

Individual evidence

  1. ^ McGrail, Sean: Boats of the World: From the Stone Age to Medieval Times . Oxford University Press, Oxford 2004, ISBN 978-0-19-927186-3 , pp. 86 .