This clock is 2.5 inches square and was designed to fit in the dashboard of a car. It has provision for internal illumination. The clock is almost entirely of metal construction with plastics only used for electrical insulation.
There is a threaded pipe at the back for connection of the hand-set control (probably by a flexible cable brought out to the dashboard).
The impulse coil is mounted to one side of the movement, with flat pole-pieces
extending round to either side of the balance wheel. Magnets are mounted
on the brass balance wheel. The hands are driven by an inverted Sully
escapement.
A pin on the under side of the balance wheel makes contact with a pivoted spring contact to complete the electrical circuit. As with all mechanical switches, dirt and corrosion of the contacts due to sparking will eventually make the clock inaccurate or unreliable.