Scaffolding and hollerith tabulator: what they have in common

1. Step 1. Scaffolding — has part — Ladder. Ladders between the levels.
2. Step 2. Ladder — is part of — Fire truck. An extending ladder.
3. Step 3. Fire truck — uses — Fire hydrant. Connection.
4. Step 4. Fire hydrant — is made of — Cast iron. A hydrant is cast iron.
5. Step 5. Cast iron — is material for — Hollerith tabulator. The casing is cast iron.

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