database is made of the stones
have megalithic art on it. At this moment it holds some 475 stones of
570 present (Eogan , page 167) in
(this is caused mostly due to missing stones from Knowth).
In due coarse I hope to have all stones in there.
The database has the following
This is build up as: <Site>|[<Official name>][_<Non
Site is always present (like Newgrange, Fourknocks I, etc.) The
name> is the name used in archaeological literature [if known],
<non standard name> is invented by the writer of the book or
where the stone can be found in the megalithic
This can be kerb, passage or chamber and a recess
can be present in the passage or the chamber.
The level where the
stone can be found
Under ground (0), just above ground (1, like: a sill
stone), above ground (2, like: a kerb stone or orthostat),
or lintel stone (3) or a roof stone (4).
of surfaces that are covered with megalithic art
References to literature
This consists of a reference number and page numbers where additional
information is available as photo, drawing and/or text.
The following reference numbers are used (Grade gives an idea of the
used for making the drawings, the higher the figure the better
, page 59)):
In the future the geometric forms and compositions per surface
catalogued. A start has been made with the 'radials'.
A case study on compositions
A case study has been done on megalithic art
that seem to be repeated at several location and with approximately the
same attributes. At this moment I don't have the impression that these
objects are phosphenes. An example of these
The three double spirals at Newgrange
Black&white version from O'Kelly (, page
177 and plate XII) Coloring and possible symbolism by Reijs 
Would the three double spirals represent mother (yellow), father
(blue) and the child(green)?
I found some text in "Waar lag Troje?" (Peursen, A. van, bres
juni/juli 2003, page 99), which describes the work of a Dutch writer
Jacob Wilkens on Troy
in England) and refers to the triskele
(I translated the below from Dutch):
"The symbol of celtic life vision was the triskele; an icon of three
united waves. In all things on earth this unity can be seen, consisting
of three co-existing elements: beside the two counter-elements
as dualism) is a third element that connects and embraces the two
This text describes very well the above picture:
the two counter-elements (the blue and yellow spiral; I call them
the third element embracing the two others (the green spiral; I
But this does not describe the layout of the official triskele
so very well, in my opinion. So I was wondering where the above text
from or were there different versions of the triskele! It would be
to know if there is something related to the above
so that I can draw some possible analogies. Please provide your
feedback on this.
Shimmering, in a spiral seen as a motion of spokes, is intriguing. Here
is a black&white sample of the spiral on Newgrange stone C2, which
clearly shows this:
If one moves one's head, one can
experience this motion of spokes (shimmering).
Another simulation video is here:
This effect is caused by
the negative retinal afterimage (also called retinal Complementary
After Image, CAI).
The afterimage is more pronounced when the contrast between light and
dark patches is bigger (Petrov 
and Francis ). Quoting
soon as the observer's motion (and the succession of afterimages) is
established, the spokes' motion ceases, which is consistent with
illusory motion being observed only in the beginning or during the
reversal of the observer's motion relative to the stimulus.
I am in search of models.literate, ideas that can simulate this effect,
so that I can
simulate it using pictures of the real art. If you have ideas, let me
I would like to thank the following people for their help and
feedback: John Cleff
and all other unmentioned people. Any remaining errors in methodology
results are my responsibility of course!!! If you want to provide
feedback, let me