Flame trench and hollerith tabulator: what they have in common

1. Step 1. Flame trench — is part of — Launch complex. A pit that carries away the hot gases.
2. Step 2. Launch complex — uses — Rocket. Launching rockets.
3. Step 3. Rocket — is made of — Paper. The first rockets were paper tubes filled with gunpowder.
4. Step 4. Paper — is material for — Punched card. Punched cards are stiff card.
5. Step 5. Punched card — is used in — Hollerith tabulator. The 1890 census data was encoded on punched cards.

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