Developed by the British General Post Office, this portable Wheatstone bridge contains precision resistor coils and a galvanometer. Early telephone and telegraph engineers used it to locate line faults by measuring the resistance of the wire to the break or short circuit. The operator adjusts brass pegs to balance the bridge and calculate the exact distance to the fault.
Heard on the job
The old engineer still had a brass Post Office box sitting on his shelf from his days tracing copper faults.
Also heard as
- PO box