The wells from which the supplies of natural gas are obtained in the United States are drilled and cased in the same manner as the oil wells.
At this period ploughs were made almost wholly of wood, the mouldboard being cased with plates of iron.
The drum, when round ropes are used, is a plain broad cylinder, with flanged rims, and cased with soft wood packing, upon which the rope is coiled; the breadth is made sufficient to take the whole length of the rope at two laps.
In the centre, the oblong pyramid of rubble cased with hewn stone and cemented 375 X 300 ft.
