Ref No: 71

Case:

Movement metal cased in high quality dovetailed hardwood box with internal soundproofing.
Size: Box roughly 6 inches square.

Movement:

Clockwork actuating a contact every 30 secs (from memory)

Condition:

New and in original outer cardboard packing.

Notes:

Royal Air Force item dating from the 1939-45 war. Made by Westinghouse Electric manufacturing Co. USA

Can Someone please tell me the exact use/purpose of this timer