Clinical thermometer and chisel: what they have in common

1. Step 1. Clinical thermometer — evolved into — Digital thermometer. A replacement for the mercury thermometer.
2. Step 2. Digital thermometer — has part — Liquid-crystal display. The reading is on an LCD.
3. Step 3. Liquid-crystal display — has part — LED. LED backlighting.
4. Step 4. LED — is part of — Street light. LEDs.
5. Step 5. Street light — is part of — Tunnel. Lighting.
6. Step 6. Tunnel — uses — Chisel. Hezekiah’s Tunnel was cut by hand with chisels.

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