Quarter circle with degree scale and heat pump: what they have in common

1. Step 1. Quarter circle with degree scale — is part of — Quadrant. A scale from 0 to 90°.
2. Step 2. Quadrant — has part — Plumb bob. A plumb line shows the vertical.
3. Step 3. Plumb bob — is made of — Stone. The bob of a plumb line is stone or copper.
4. Step 4. Stone — is material for — Ice house. Ice houses were built of stone and sunk into the ground.
5. Step 5. Ice house — evolved into — Refrigerator. The refrigerator replaced natural ice.
6. Step 6. Refrigerator — works like — Heat pump. A heat pump is a refrigerator that heats the house.

Open Evothings