This peculiar stone, like many other holed stones, has an association with contract making. It is said that the monks secured possession of the island by shaking hands through this stone.
What makes this stone different to other holed stones is that it is not a monolith like the majority, but a low flat boulder about 30cm high and 1m square in plan.
Presumably, if the monks sealed the deal in this way then there would have been a long history of the stone being used for making contracts. Again this points to pre-Christian ritual on the island.
This is an explanation of (and a bit of a disclaimer for) the coordinates I provide.
Where a GPS figure is given this is the master for all other coordinates. According to my Garmin these are quite accurate.
Where there is no GPS figure the 6 figure grid reference is master for the others. This may not be very accurate as it could have come from the OS maps and could have been read by eye. Consequently, all other cordinates are going to have inaccuracies.
The calculation of Longitude and Latitude uses an algorithm that is not 100% accurate. The long/lat figures are used as a basis for calculating the UTM & ITM coordinates. Consequently, UTM & ITM coordinates are slightly out.
UTM is a global coordinate system - Universal Transverse Mercator - that is at the core of the GPS system.
ITM is the new coordinate system - Irish Transverse Mercator - that is more accurate and more GPS friendly than the Irish Grid Reference system. This will be used on the next generation of Irish OS maps.