They stacked rocks with center holes (tube or doughnut shaped) from the surface to the deep stone layer as a guide for their drills (similar to today's guide tubes).
管状或中空管状的中心孔从地表到深石岩石层放满石头，以作为铁转的探头，作用类似今天的导管。
2
They'd started using 'harmonic drills in their mines. The stone was unhappy.
他们在矿井里用谐和钻孔机，让石头不高兴了。
3
Main scope of business:Chinese chestnuts, silkworm cocoon, grain, traditional Chinese medicine, wild vegetables, stone products, fittings of rock drills etc.