Indian circle
The Indian circle is a process with which it is possible without a compass to determine the cardinal points with the help of the daily orbit of a point shadow created by the sun . As a rule, the point that casts the shadow ( nodus ) is the tip of a stick inserted vertically into the ground. The generally hyperbolic shadow orbit is symmetrical to the north-south direction. Primarily, one determines east and west with the help of the two intersection points of the daily path with a circle, the center of which is at the base of the rod. The radius of the circle is chosen so that the day's path runs within the circle for a time before and after noon. The line connecting the two intersection points has an east-west direction , the connection between the center of the line and the base point has a north-south direction .
It makes sense to first mark the shadow line on the floor, and then draw a circle to the ends of the shadow line. Advantage: The circle has the largest possible radius, so that the direction measurement is the most accurate.
The process takes its name from the oldest sources preserved for it, which come from India . The exact age of the procedure is unknown, but its implementation requires a minimum of astronomical and geometrical knowledge. The fact that most ancient cultures and also the Neolithic farmers knew this technique is shown by the largely precise alignment of their graves or the dead people placed in them according to the cardinal points. In the late Neolithic period, women were buried with their heads facing east and men with their heads facing west. The dead were placed on the side of the body that allowed the face to face south.
See also
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- ↑ At sunrise and sunset, the shadow points are at infinity. An Indian circle can be large, but conveniently not arbitrarily large (especially not infinitely large).
Web links
- www.scinexx.de: The trick with the Indian circle
- www.rainerstumpe.de: The Indian Circle (private site)