Inventions in the Century

by William Henry Doolittle

Other stone-cutting machines had for their objects the cutting and moulding the edges of tables, mantels and slabs; and the cutting of circular and other curved work. In the later style of machine the cutter fixed on the end of a spindle is guided in the desired directions on the surface of the stone by a pointer, which, attached to the cutter spindle, moves in the grooves of a pattern also connected to the rotating support carrying the cutter.

Other forms of most ingenious stone-dressing and carving machines have been devised for cutting mouldings, and ornamental figures and devices, in accordance with a model or pattern fixed to the under side of the table which carries the stone or marble to be dressed; and in which, by means of a guide moving in the pattern, the diamond cutter or cutters, carried in a circular frame above the work and adjusted to its surface, are moved in the varying directions determined by the pattern. A stream of water is directed on the stone to clear it of the dust during the operations. The carving of stone by machinery is now a sister branch of wood carving. Monuments, ornamentation, and intricate forms of figures and characters are wrought with great accuracy by cutting and dressing tools guided by the patterns, or directed by the hand of the operator.

For the dressing of the faces of grindstones, special forms of cutting machines have been devised.

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.

The setting of the movable jaw at an incline enables the large stone to be first cracked, the movable jaw then opens, and as the stone falls lower between the more contracted jaws, it is broken finer, until it is finally crushed or pulverized and falls through at the bottom. The movable jaw is adjustable and can be set to crush stones to a certain size.

As the rock drill made a revolution in blasting and tunnelling, so the Blake crusher revolutionised the art of road making. “Road metal,” as the supply of broken stones for roads is now called, is the fruit of the crusher. Hundreds of tons of stone per day can be crushed to just the size desired, and the machine may be moved from place to place where most convenient to use.