Using a machine called the Greathead Shield, a team of just 12 workers could bore through the earth, carving deep underground tunnels through the London clay.

运用大头盾构机，只要 12 名工人组成的团队就可以在伦敦的地下深处挖掘隧道。

This is the only complete Greathead shield on the entire London Underground network, and this has been here since 1904 and will be here for the foreseeable future.

这是全伦敦地铁管网里唯一一个完整的大盾构机，从1904年起，就一直在这里，以后也会在。