Postal service and barrel: what they have in common

1. Step 1. Postal service — uses — Steam locomotive. Mail trains.
2. Step 2. Steam locomotive — has part — Chimney. Smoke from the firebox leaves through the locomotive's chimney.
3. Step 3. Chimney — is made of — Brick. Chimneys are brick.
4. Step 4. Brick — is material for — Arch. Arches were built of brick or stone.
5. Step 5. Arch — works like — Barrel. Staves squeezed by hoops hold their shape by the same compression as the stones of an arch.

Open Evothings