Barrel hoops and watt steam engine: what they have in common

1. Step 1. Barrel hoops — is part of — Barrel. Metal hoops pull the staves together.
2. Step 2. Barrel — works like — Arch. Staves squeezed by hoops hold their shape by the same compression as the stones of an arch.
3. Step 3. Arch — is made of — Brick. Arches were built of brick or stone.
4. Step 4. Brick — is material for — Chimney. Chimneys are brick.
5. Step 5. Chimney — is part of — Steam locomotive. Smoke from the firebox leaves through the locomotive's chimney.
6. Step 6. Steam locomotive — has part — Watt steam engine. A steam locomotive is driven by a steam engine.

Open Evothings