The slave dial on the right hand side has a 14 inch face whilst the main clock is 12 inches. The black box beneath the slave dial is the control unit, its label on the front cover gives it as a "Model 601-9".
The inside contains a transformer, a selenium rectifier, relay and fuses. Note the proximity of the two mains input terminals at bottom left. They are barely an inch below the clocks low voltage terminals, making it very easy to touch these when working on the unit. A potentially fatal thing to do if one had forgotten to remove the mains plug! In this case modern day Health & Safety Inspectors would actually have something to justify their hysteria.
The circuit diagram is pasted inside the lid
