The ball takes between 15 seconds and one minute to run down the zigzag track, where it trips the escapement which in turn reverses the tilt of the tray and at the same time causes the hands of the clock to move forward.
Thus the angle of the plate reverses and the clock hands move forward between one and four times every minute.
Congreve appears to have been unaware that rolling ball clocks had been invented earlier by both Nicolas Grollier de Servière and Johann Sayller.
Congreve, who was not a clock maker, hired Gravell & Tolkien to produce the first working version, which he then presented to the Prince of Wales in 1808.
This version was weight-driven, but the second design, which appears to have been constructed by John Moxon, was spring-driven.