Tracer arm and boiler: what they have in common

1. Step 1. Tracer arm — is part of — Planimeter. A stylus traces the outline.
2. Step 2. Planimeter — has part — Wheel. A measuring wheel computes the area.
3. Step 3. Wheel — includes — Water wheel. A water wheel is a wheel with paddles turned by flowing water.
4. Step 4. Water wheel — is part of — Trip hammer. The shaft was turned by a water wheel.
5. Step 5. Trip hammer — evolved into — Steam hammer. The mechanization of forging.
6. Step 6. Steam hammer — has part — Boiler. A boiler supplies the steam.

Open Evothings