Perhaps I've got the wrong place, but Liss is very close and this certainly sounds like a ballaun, of which one is at these coordinates. The story is entitled "A Peculiar Stone".
There is a square stone about eight inches long and eight inches wide in this locality. It is situated in a square field in the townland of Liss.
In the centre of the stone there is a hole which is always filled with water. It is supposed Saint Patrick knelt on it and left the print of his knee on it.
It is supposed that if you washed your hands with the water which is in the print you would never get warts.