It was a slow and tedious task to drill holes through stone by hand tools; and it was indeed a revolution in this branch of the art when steam engines were employed to rotate a rod armed at its end with diamond or other cutters against the hardest stone. This mode of drilling also effected a revolution in the art of blasting. Then, neither height, nor depth, nor thickness of the stone could prevent the progress of the drill rod. Tunnels through mountain walls, and wells through solid quartz are cut to the depth of thousands of feet. One instance is related of the wonderful efficiency on a smaller scale of such a machine: The immense columns of the State Capitol at Columbus, Ohio, were considered too heavy for the foundation on which they rested. The American Diamond Rock Boring Company of Providence, Rhode Island, bored out a twenty-four inch core from each of the great pillars, and thus relieved the danger. In the most economical and successful stone drills _compressed air_ is employed as the motive power to drive the drills, which may be used singly or in gangs, and which may be adjusted against the rock or quarry in any direction. When in position and ready for work a few moments will suffice to bore the holes, apply the explosive and blast the ledge. 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. _Crushing_:--Among the most useful inventions relating to stone working are machines for crushing stones and ores, and assorting them. The old way of hammering by hand was first succeeded by powerful stamp hammers worked by steam. Both methods of course are still followed, but they demand too great an expenditure of force and time. About a third of a century ago, Eli Whitney Blake of New Haven, Connecticut, was a pioneer inventor of a new and most successful type of stone breaking machine, which ever since has been known as the “Blake Crusher.” This crusher consists of two ponderous upright jaws, one fixed and the other movable, between which the stones or ores to be crushed are fed. Each of the jaws is lined with the hardest kind of chilled steel. The movable jaw is inclined from its lower end from the fixed jaw and at its upper end is pivoted to swing on a heavy round iron bar. The movable jaw is forced toward the fixed jaw by two opposite toggle levers set, in one form of the crusher, at their inner ends in steel bearings of a vertical vibrating, rocking lever, one of the toggles bearing at its outer end against the movable jaw and the outer toggle against a solid frame-work. The rocking lever is operated through a crank by a steam engine, and as it is vibrated, the toggle joint forces the lever end of the movable jaw towards the fixed jaw with immense force, breaking the hardest stone like an eggshell.