In the grounds of Tallaght Priory, beside the Friar's Walk, you will need to get permission to visit these stones.
I was surprised by the size of the bullaun stone having only seen close-up photographs with no idea of scale. It's an irregular shape conglomerate, maybe roughly two thirds of a metre squarish. The bullaun is about 20 cms wide and 15 cms deep.
Beside it is a stone described by Patrick Healy in All Roads Lead to Tallaght (South Dublin Libraries) as: "…a large granite stone with a hole through it. The hole is narrower at the ends and in the middle, somewhat like an hourglass, but is now screw-threaded as stated by O'Curry. Beside the hole is a round hollow."
I was kindly brought here by Brother Michael. Thanks.