Acetylene and hollerith tabulator: what they have in common

1. Step 1. Acetylene — is used in — Headlight. The first headlamps burned acetylene.
2. Step 2. Headlight — is part of — Car. Headlights.
3. Step 3. Car — has part — Turn signal. Turn signals.
4. Step 4. Turn signal — uses — Relay. A flasher relay.
5. Step 5. Relay — is part of — Hollerith tabulator. Relays controlled the sorting box.

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