Hammerstone e tunnelling shield: o que têm em comum

1. Passo 1. Hammerstone — é utilizado em — Stone tool. A hammerstone for knapping.
2. Passo 2. Stone tool — faz parte de — Spear. Early spearheads were made of stone.
3. Passo 3. Spear — evoluiu para — Lança de fogo. The fire lance was a spear with a tube of gunpowder — the first step to firearms.
4. Passo 4. Lança de fogo — utiliza — Gunpowder. A gunpowder charge.
5. Passo 5. Gunpowder — evoluiu para — Dinamite. A replacement for gunpowder in mining.
6. Passo 6. Dinamite — funciona como — Tunnelling shield. Two ways of driving tunnels — mechanical and explosive.

Abrir Evothings