Lightning rod and telephone: what they have in common

1. Step 1. Lightning rod — uses — Electrical conduction. It carries the current into the ground.
2. Step 2. Electrical conduction — is used in — Copper wire. Copper conducts current well.
3. Step 3. Copper wire — is part of — Electrical telegraph. Communication lines.
4. Step 4. Electrical telegraph — evolved into — Telephone. The telephone grew out of attempts to send several signals over telegraph lines (the “harmonic telegraph”).

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