In a previous article, the 7,500 foot-long Erdevan alignments were seen to have been a long count of the Saros period of 19 eclipse years versus the distance to Mane Groh dolmen of 19 solar years, this probably conceptualized as an 18-19-6 near-Pythagorean triangle, whose inner angle is the bearing from east of Mané Groh. However, the path directly east caused the actual alignments, counting the Saros, to veer south to miss the hill of Mané Bras.
It has been remarked that the form of the northern alignments of Edeven were similar
to those starting at Le Menec’s egg-shaped stone circle 4.25 miles away, at a
bearing 45 degrees southeast. Whilst huge gaps have been caused in those of
Edeven by agriculture, the iconic Le Menec alignments seem to have fared better
than the alignments of Kermario, Kerlescan and Petit Menec which follow it
east, these being known as the Carnac Alignments above the town of that name.
One similarity between alignments is the idea of starting and terminating them with ancillary structures such as cromlechs (stone kerb monuments), such as the Le Menec egg and, despite road incursion, a3-4-5 structure similar to Crucuno, aligned to the midsummer sunset by a length 235 feet long. This is the number of lunar months in the 19 year Metonic period and is factored 5 times 47. Another similarity may be seen in Cambray’s 1805 drawing of these Kerzerho alignments, at the head of ten stone rows marching east (figure 1).
In 1973, Alexander Thom found the Crucuno rectangle to have been
“accurately placed east and west” by its megalithic builders, and
“built round a rectangle 30 MY [megalithic yards] by 40 MY” and that
“only at the latitude of Crucuno could the diagonals of a 3, 4, 5
rectangle indicate at both solstices the azimuth of the sun rising and setting
when it appears to rest on the horizon.” In a recent article I found metrology was used between the Crucuno
dolmen (within Crucuno) and the rectangle in the east to count 47 lunar months,
since this closely approximates 4 eclipse years (of 346.62 days) which is the
shortest eclipse prediction period available to early astronomers.
About 1.22 miles northwest lie the alignments sometimes called
Erdeven, on the present D781 before the hamlet Kerzerho – after which hamlet
they were named by Archaeology. These stone rows are a major complex monument
but here we consider only the section beside the road to the east. Unlike the
Le Manec Kermario and Kerlestan alignments which start north of Carnac,
Erdevan’s alignments are, like the Crucuno rectangle accurately placed east and
Table des Marchands, a dolmen at Lochmariaquer, can explain how the Megalithic came to factorise 945 days as 32 lunar months by looking at the properties of the numbers three, four and five. At that latitude, the solstice angle of the sun on the horizon shone along the 5-side of a 3-4-5 triangle to east and west, seen clearly at the Crucuno Rectangle "Lunar Counting from Crucuno Dolmen to its Rectangle".
Before numbers were individually notated (as with our 3, 4 and 5
rather than |||, |||| and |||||) and given positional notation (like our
decimal seen in 945 and 27), numbers were lengths or marks and, when marks are
compared to accurately measured lengths measured out in inches, feet, yards,
etc. then each vertical mark would naturally
have represented a single unit of length. This has not been appreciated
as having been behind marks like the cuneiform for ONE; that it probably meant
“one unit of length”.
It is not immediately obvious the Crucuno dolmen (figure 1) faces the Crucuno rectangle about 1100 feet to the east. The role of dolmen appears to be to mark the beginning of a count. At Carnac’s Alignments there are large cromlechs initiating and terminating the stone rows which, more explicitly, appear like counts. The only (surviving) intermediate stone lies 216 feet from the dolmen, within a garden and hard-up to another building, as with the dolmen (see figure 2). This length is interesting since it is twice the longest inner dimension of the Crucuno rectangle, implying that lessons learned in interpreting the rectangle might usefully apply when interpreting the distance at which this outlier was placed from the dolmen. Most obviously, the rectangle is 4 x 27 feet wide and so the outlier is 8 x 27 feet from the dolmen.
Around Carnac in Brittany the land is peppered with uniquely-formed megalithic designs. In contrast, Great Britain’s surviving monuments are largely standing stones and stone circles. One might explain this as early experimentation at Carnac followed by a well-organised set of methods and means in Britain. What these experiments near Carnac were concerned with is contentious, there being no appetite, in many parts of society, for a prehistory of high-achieving geometers and exact scientists. Part of the problem is that pioneers interpreting monuments are themselves hampered by their own preferences. Once Alexander Thom had found the megalithic yard as a likely building unit, he tended to use that measure to the exclusion of other known metrological systems (see A.E. Berriman’s Historical Metrology. Similarly, John Neal’s breakthrough in All Done With Mirrors, having found the foot we still use to be the cornerstone of ancient metrology, led to his ambivalent relationship to the megalithic yard. Neal’s interpretation of the Crucuno rectangle employs a highly variable set of megalithic yards, perhaps missing the simpler point, that his foot-based metrology is supported as present within the dimensions of the Crucuno rectangle; said by Thom to be a “symbolic observatory” of the sun: this monument was an educational device, in which Neal finds the geometry of “squaring the circle” which, as we see later, was probably the Rectangle’s main metrological meaning.