Sonar and shaduf: what they have in common

1. Step 1. Sonar — is part of — Submarine. Underwater acoustics.
2. Step 2. Submarine — has part — Propeller. A propeller.
3. Step 3. Propeller — evolved from — Archimedes’ screw. The first propellers by Smith and Ericsson were a variation on the Archimedes’ screw.
4. Step 4. Archimedes’ screw — is used in — Irrigation. The Archimedes’ screw lifted water for irrigation.
5. Step 5. Irrigation — uses — Shaduf. The shaduf fed water into the canals.

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