With the help of this simple instrument, the cardinal directions can be determined accurately even without a compass. To do this, the movement of the sun's shadow must be observed and marked for one day.
How it works: Place the sun compass on a sunny, horizontal surface and point it towards the position of the sun at midday. Then, for one day, at least between 11 a.m. and 2 p.m., follow the movement of the shadow and mark the points where the tip of the shadow touches one of the circle lines. In the evening, connect the two points of contact that lie on the same circle with a line. These lines run exactly east-west. If you halve these lines and connect the midpoints with the centre of the circles, you will obtain a line running exactly north-south.
The Indian circle: This method is called the "Indian circle". It was already known in ancient times and is also ideal for transferring measurements to a large area, such as a school playground. All you need is a string compass and a long wooden stick.
