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 ThomScottish engineer 1894-1985. Discovered, through surveying, that Britain's megalithic circles expressed astronomy using exact measures, geometrical forms and, where possible, whole numbers. 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 pior π: The constant ratio of a circle's circumference to its diameter, approximately equal to 3.14159, in ancient times approximated by rational approximations such as 22/7. 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).

The bay of Quiberon is south of CarnacAn extensive megalithic complex in southern Brittany, western France, predating the British megalithic. and it has a small seaside town called Quiberon on a southern peninsular looking out to the east. Alexander Thom found Quiberon on a remarkably large set of sightlines, suitable for horizon astronomy of the Sun and Moon, over the Bay between Quiberon and the Grand Menhir at Loqmariaquer.

The suburb of Quiberon-St Pierre hosts the remains of a “cromlech” of the Type-1 egg-geometry, surveyed by Thom on one of his visits . Its semicircular side faces east and Thom found its likely perimeter (on “slender” but careful evidence) to have been 135 megalithic rods in perimeter. In this post we suggest one of the functions of the cromlechBreton word for a rounded kerb monument or stone circle. was to study the geocentric period of the planet Jupiter, its “synod” of 398.88 days and, in a follow up, how the nodes were probably tracked alongside Jupiter and the Moon. Figure 2 is my version of his survey, featured at the beginning of this post.

The egg is unusual. It has a pair of forming triangles with *identical sides* (17) and hence an inner angle of 45 degrees. Seventeen on each smaller side nearly creates the integer 24 (24.0416) on the longest side. The units are megalithic rods of 2.5 x megalithic yards as 6.8 feet per rod. At some stage in Carnac’s megalithic period , the idea of counting days as inches (i.e. in day-inches) was supplemented by counting lunar months (of 29.53059 days) instead of days, using the megalithic yardAny unit of length 2.7-2.73 feet long, after Alexander Thom discovered 2.72 ft and 2.722 ft as units within the geometry within the megalithic monuments of Britain and Brittany. as a month (for reasons explained elsewhere). In this case, ten megalithic rods were probably being used to count each lunar month since there are 13.5 lunar months in a Jupiter synod (398.88 days) so that 135 rods, as perimeter, would then equal that synod.

If the egg was the synod of Jupiter then the Earth is likely to have been placed in the centre of the forming circle. The axis of symmetry, at the maximum extension of the egg, can be interpreted as the loop of Jupiter (when the Earth passes Jupiter’s outer orbit) : at its “superior conjunction”. And the inferior conjunction, of Earth, Sun and Jupiter beyond the Sun, is then on the opposite eastern side.

One can see that twelve full moons (white) and new moons (black) occur on the eastern semicircle and so, the whole forming circle represented the lunar year (354.367 days) of 12 lunar months, going around the Earth at its centre; see figure 4.

Each lunar month is 10 MR but, because of the half lunar month in Jupiter’s synod, the *full *moons of every other synod will land on the location of a previous *new *moon – and visa versa. This will also be relevant to the lunar year circle which will have 24 stations for the moon whilst the synod egg will have 27 stations. The ratio of 27/24 equals the 9/8 Pythagorean tone at the heart of the harmony between the outer planets and the lunar year. The lunar stations are therefore 5 MR apart and this cromlech of St Pierre (meaning stone) could have been used to continuously study the relative configuration of the Moon and Jupiter or, indeed, to simulate these into the future or past.

In the next post I shall show how this egg could also track the nodal cycle of the Moon.