Feather and Wedge

Establish the asymmetry the method exploits.

1. Stand on a small slab of stone laid flat on the ground — it takes the compression easily.
2. Support the same slab at both ends only and load the middle.
3. It breaks at a fraction of the load.

Granite has directional weakness, and quarrymen have names for it.

1. Look for the rift — the direction it splits most easily.
2. Find the grain — the next easiest.
3. The hardway is the third, and you avoid it.

Evenly spaced, equal depth, all in line.

1. Drill holes along the marked line, typically 100-150 mm apart in granite.
2. Drop two feathers into each hole, with their flat backs facing along the line.
3. Insert a plug between each pair, leaving it standing proud.

Patience is the technique. Eye protection throughout.

1. Tap each plug once, lightly, working along the row.
2. Return to the start and repeat, again and again.
3. Listen — the note changes and a hairline appears before it goes.

Splitting stone with wedges is ancient. Egyptian and Roman quarries show wedge slots, and there is a long-running argument about whether wooden wedges were soaked to swell and split the stone — the evidence is genuinely mixed, and dry wooden wedges hammered in work perfectly well, so the soaking story should be treated as plausible rather than established.

The modern plug-and-feather set is a nineteenth-century refinement associated with New England granite quarrying, where it replaced the older method of cutting a continuous slot with a chisel. It is far faster and wastes almost no stone — a slot turns a line of material into dust, while a split consumes only the drill holes.

Look for the marks. Half-round grooves along the edge of a granite kerbstone, bridge abutment or old building block are the remains of the drill holes, sliced in two by the split. They are all over nineteenth-century masonry once you know to look, and they date the stone as surely as a tool mark can.

Still current. Quarries use hydraulic splitters and diamond wire now, but plug and feather remains standard for trimming, for work where vibration matters, and for conservation — and a set of feathers and wedges costs very little and needs no power. It is one of those techniques that industrialisation improved without ever replacing.

Safety: eye protection without exception — steel-on-steel throws chips, and the stone releases suddenly. Keep hands clear of the split line and expect the two halves to move.