The egg-shaped stone circles of the megalithic, in Brittany by c. 4000 BC and in Britain by 2500 BC, seem to express two different astronomical time lengths, beside each other as (a) a circumference and then (b) a longer, egg-shaped extension of that circle. It was Alexander Thom who analysed stone circles in the 20th century as a hobby, surveying most of the surviving stone circles in Britain and finding geometrical patterns within irregular circles. He speculated the egg-shaped and flattened circles were manipulating pi so as to equal three (not 3.1416) between an initial radius and subsequent perimeter, so making them commensurate in integer units. For example, the irregular circle would have perimeter 12 and a radius of 4 (a flattened circle).
However, when the forming circle and perimeter are compared, these can compare the two lengths of a right-triangle while adding a recurring nature: where the end is a new beginning. Each cycle is a new beginning because the whole geocentric sky is rotational and the planetary system orbital. The counting of time periods was more than symbolic since the two astronomical time periods became, by artifice, related to one another as two integer perimeters that is, commensurate to one another, as is seen at St Pierre (fig.3).
In my academia.edu paper on lunar simulators, based upon the surviving part of a circular structure at Le Manio (Carnac, Brittany), a very simple but poor approximation to PI could be assumed, of 82/26 (3.154) since there seem to have been 82 stones in the circle and the diameter was 26 of the inter-stone distance of 17 inches. The number 82 is significant to simulation of the moon’s orbit since that orbit is very nearly 27 and one third days long (actually 27.32166 days). In three orbits therefore, there are almost exactly 82 days and in day-inch counting that is 82 day-inches. Also of interest is the fact that in three orbits, the exact figure would be 81.965 day-inches which approaches the megalithic rod of 2.5 MY as 6.8 feet.
Sacred Number and the Lords of Time interpreted Thom’s megalithic fathom of 6.8 feet (as 2.72 feet times 2.5) found at Carnac’s Alignments as a useful number of 82 day-inches between stones in the stone rows of Le Menec. After 82 days, the moon is in almost exactly the same place, amongst the stars, because its orbit of 27.32166 days is nearly 27 and one third days. Three orbits sums to nearly 82 days. But the phase of the moon at that repeated place in the sky will be different.