Holter monitor and newcomen engine: what they have in common

1. Step 1. Holter monitor — evolved from — Electrocardiograph. A wearable ECG.
2. Step 2. Electrocardiograph — is made of — Silver. The quartz string of Einthoven’s galvanometer is silvered.
3. Step 3. Silver — is material for — Syringe. Early needles were silver.
4. Step 4. Syringe — has part — Piston. A plunger.
5. Step 5. Piston — is part of — Newcomen engine. Atmospheric pressure moves the piston.

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