The May/August Cross Quarter Display
The third device discovered by the pioneer explorers, Alan Gillespie and Jon Polansky, was this unique sun and shadow display on this paired set of sunsymbols. This notes the August and February cross quarters. This is indicative of the relationship of Lugh and Bel (Baal). It is also clue as to how the ancient archaeoastronomers figured out the day to celebrate the festivals using solar position. They were not dependent on solar position on the horizon, obscured at the site by a mountain range, but the position of the sun in the heavens. It is probably not coinsidence that the sun symbols share their existence on a wall with an image of Lugh.
The fact that the display uses a right angle of light interacting on the intended target is significant. This is indicative of their reverence for the geometric function of the right angle, a necessary component to any geometric calculation, even in modern times.
See EPIGRAPHY for a report by Alan Gillespie published in the Epigraphic Society Occasional Papers.