He said no more, but signed to me to lift a heavy wooden corb with an iron loop across it, and sunk in a little pit of earth, a yard or so from the mouth of the shaft. I raised it, and by his direction dropped it into the throat of the shaft, where it hung and shook from a great cross-beam laid at the level of the earth. A very stout thick rope was fastened to the handle of the corb, and ran across a pulley hanging from the centre of the beam, and thence out of sight in the nether places.
Source: wiktionary