The cleaning away of submarine ledges in harbours, such as the great work at Hell Gate in the harbour of New York, has thus been effected. 威廉·亨利·杜利特.世纪发明.
The immense veins of magnetic ore lie close to the surface and are mined or quarried by working along a series of benches or ledges. 佚名.神奇的知识之书.