Large lead balls and railway semaphore: what they have in common

1. Step 1. Large lead balls — is part of — Torsion balance. The attracting masses.
2. Step 2. Torsion balance — is made of — Silver. The suspension fibre is a thin silver wire.
3. Step 3. Silver — uses — Electrical conduction. The best conductor.
4. Step 4. Electrical conduction — is used in — Track circuit. The wheelset closes the circuit.
5. Step 5. Track circuit — is part of — Automatic block signalling. Track circuits.
6. Step 6. Automatic block signalling — has part — Railway semaphore. Signals.

Open Evothings