Wow! This watch is mad.
The point in time is presented by the fixed position of the ball. The length of time is interpreted by the free movement of the ball across the face of the watch. The ball moves to and fro across the face of the watch with the flow of the wearer’s arm movements, but as soon as the ABACUS reaches a horizontal position, the ball moves as if by magic – or at least by magnetism – to the right point in time.