It may be conceded that Mr. Sommeiller has constructed au inge- nious machine which fulfills the following conditions: 1.
Then the clutch box, impelled by the spring, catches and turns the screw, and the striking cylinder advances till the fork is caught by the following tooth of the rack, and thus disengages the clutch.  It may be conceded that Mr. Sommeiller has constructed au inge- nious machine which fulfills the following conditions: 1.  It strikes hard and rapid blows upon the rock.