South-pointing chariot

As an antique compass car transportable direction pointer is called. In contrast to normal compass the design principle is not based on the geomagnetism, but also to the detection of the differential rotation of two wheels of the same size arranged in parallel by means of a differential transmission (more precisely, a Subtraktionsgetriebes ).

The compass car is practically a cart with two connected via a differential wheels on a common axis represents, on the one hand attached thereto, of the carts always shows itself when turning in the same direction.

The first documented construction of a compass car is the Chinese inventor Ma Jun attributed (around 200-265 ), although as early as 2600 BC the Chinese Emperor Huang Di, the use of such a device is said. The compass car was then used to keep the orientation in military conflicts even in fog.