Square paper bag bottom and piston pump: what they have in common

1. Step 1. Square paper bag bottom — is part of — Paper bag. Margaret Knight’s rectangular bottom.
2. Step 2. Paper bag — is made of — Paper. Paper.
3. Step 3. Paper — is used in — Rotary printing press. It prints on a paper web.
4. Step 4. Rotary printing press — has part — Watt steam engine. The first rotary presses were steam-driven.
5. Step 5. Watt steam engine — evolved from — Piston pump. The first steam engines (Newcomen’s) pumped water out of mines by driving pumps.

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