...tortion gives to the bar of iron a circular motion, sufficient to vary the place of the cutting chisel at each descent. When the chamber is full, the whole apparatus is raised quickly to the surface to be unloaded, and is again let down by the action of the same wheel. This process has long been practised...

...•;!> rs to the bar of iron, a circular motion, sufficient to vi iv the place of the cutting chistl et each descent. When the chamber is full, the whole apparatus is raised quickly to the surface to be unloaded, and is again let down by the action of the same wheel. This process hasbeen long practised...

...which the hole is made, and is raised up and let fall by manual labour. As the rope is raised up ami down, its tortion gives the chisel a circular motion,...chamber is full, the whole apparatus is raised quickly j to the surface, and the material it contains discharged. In cutting through a hard stratum, or under...

...tortion gives to the bar of iron a circular motion, sufficient to vary the place of the cutting chisel at each descent. "When the chamber is full, the whole apparatus is raised quickly to the surface to be unloaded, and is again let down by the action of the same wheel. This process has been long practiced...

...to the bar of iron a circular motion, suffi i el it to vary the place of the catting chisel at ucli descent. "When the chamber is full, the whole apparatus is raised quickly to the surface to be unoaded, and is again let down by the action of he same wheel. This process has been long Dracticed...

...tortion gives to the bar of iron a circular motion, sufficient to vary the place of the cutting chisel at each descent. When the chamber is full, the whole apparatus is raised quickly to the surface to be unloaded, and is again let down by the action of the same wheel. This process has long been practised...