Punched card reading press and petri dish: what they have in common

1. Step 1. Punched card reading press — is part of — Hollerith tabulator. Needles pass through the holes and close the circuit in mercury.
2. Step 2. Hollerith tabulator — is made of — Cast iron. The casing is cast iron.
3. Step 3. Cast iron — is material for — Saucepan. Old pots were made of cast iron.
4. Step 4. Saucepan — has part — Pot lid. A cap.
5. Step 5. Pot lid — is part of — Petri dish. A cap.

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