Synchronome relay unit

Info from owner:
The Synchronise Relay Unit has the following dimensions:
Height 13&3/4 inches Width 12&3/4 inches Depth 5&7/8 inches

Case Material - Oak, stained dark.
External Features - Bronzed Triple hinges on RHS (viewed from front) .
Bronzed swing catches (two off) per section. i.e. front glazed compartment and rear foundation unit.
Two key locks for each section to prevent unauthorised access.

The panels are of a modular construction:
Upper - Milli Ampere meter (to assess current flowing through respective circuits)
Relay
Pulsing Button (for advancing the chosen circuit - see below)
Flexible twisted cord (rubber insulation over tinned copper conductors, and served with cotton/rayon braiding over each insulant - coloured deep purple) terminating in -
1/4 inch jack plug to fit complementary jack socket in respective circuit panels below.

Middle Module - No 1 Circuit - 3&5/8 inches local slave dial.
1/4 inch jack socket
Normal/Advance Toggle Switch

Lower Module - No 2 circuit - features as above

Blanking Plate - Could accept another module.

To advance any given slave clock network, the 1/4 inch jack plug is inserted in to the appropriate jack socket.
The receptive Toggle Switch is thrown to 'Advance' and the pulsing button depressed the requisite number of times.
The toggle switch set back to 'Normal' after making the correction.

The milli-ampere meter indicates circuit current, and the two circuits can be balanced by means of wire-wound rheostats found adjacent to the local circuit monitoring slave dial movements behind the front panel.