Some notes by John Drewry in *Greenburn Book 3:*

Recumbent stone circles are found in the North-East of Scotland and
they are thought to be at least five thousand years old. The recumbent
stone is a very large stone lying on its side and it is flanked by two
upright stones which are of a similar size to the other stones in the circle.
The recumbent stone is always on the south-west side of the circle and it
is thought that it was used in observations of the moon. There is a fine
recumbent stone circle at Easter Aquhorthies to the north-west of
Inverurie.

Once, when I was visiting it, I met a wee man who assured me that
someone standing in the circle was much more likely to see U.F.O's than
someone standing nearby! Maybe his powers of imagination were more
developed than mine.

An article in the Scotsman revealed that this circle has unusual
acoustic properties which have been verified with scientific instruments.
Similar acoustic properties are found at the Cairns of Camster, near
Wick, in Caithness. The suggestion was that the old priests used the
acoustic properties to impress the people with their "magic" powers.