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Splitting a block with feather and wedges

The plug & feather method of stone splitting involves drilling a series of round holes in the rock spaced every six inches or so apart. ... Once the holes are drilled, two shims called feathers or half-rounds are placed in the hole and a wedge called a plug is placed between the two feathers. Using a sledgehammer, the plugs are then struck with hammer in sequence. An audible tone from the wedges changes to a 'ringing sound' when the wedges are tight. Between each series of strikes, a pause of several minutes allows the stone to react to the pressure. Eventually a crack appears along the line that was scored on the surface and the stone splits apart. Attempting to split the stone too quickly may cause the stone to "blow out" at the site of the plug or split at an undesirable section.