Bulldozer and chisel: what they have in common

1. Step 1. Bulldozer — has part — Hydraulic cylinder. The blade is raised by hydraulics.
2. Step 2. Hydraulic cylinder — is used in — Tunnelling shield. The shield was pushed forward by jacks.
3. Step 3. Tunnelling shield — is used in — Tunnel. Shield tunnelling.
4. Step 4. Tunnel — uses — Chisel. Hezekiah’s Tunnel was cut by hand with chisels.

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