This article first published at

Le Manio is a megalithic complex above and between Carnac and Loqmariaquer, in Southern Brittany's Bay of Quiberon. It is named after a large menhir, also called "the giant", which forms a foresight from all over the district, to extreme horizon events of the sun and moon, to both north and south of east-west. The site is on the highest hill in what is a low landscape and it has two components that are interlinked.

  1. The first is Menhir Geant and La Dame du Manio, embedded in the earth, which are sited on an exact east west line so as to manifest 3-4-5 triangles
  2. Above is The Quadrilateral, which has a unique shape made out of kerbs of stone, some touching, perhaps connected to the Geant and Dame in a proposed geometry involving 12-13-5 triangles.
Le Manio's Quadrilateral from the north east. The menhir is off-frame 
to the left and hence to the south.

The Monument(s) of Le Manio

A circa 2008 survey by ACEM produced data that enabled the geometries between the two to be quantified once it was recognised that megalithic yards had been employed. The result is as Figure 1, with one extra summer sunrise alignment added within the Quadrilateral.

Copy of LeManio Observatory SIMPLE

Figure 1 The geometry proposed by ACEM based upon their circa 2008 survey, with distances converted from metres to megalithic yards and an extra alignment within the Quadrilateral noticed by Robin Heath in the 2009 summer solstice event.

It is obvious from the exact numbers of megalithic yards that the geometry was conceived and laid out using this unit, the lower 3-4-5 triangle even using ten units for the 3, 4 and 5. The two 12-13-5 triangles appear to relate the location of the Quadrilateral to a point J in the north and the upper 3-4-5 triangle locates what was  called the "sun gate" at point P, points being exact survey pins.

The two 3-4-5 triangles are in a familiar "piggy backed" arrangement enabling the summer solstice sunrise to shine down the (lower) four-side and the winter solstice sunrise to shine in the sun gate on the (upper) five-side (an observation made by Howard Crowhurst. The five side of the (lower) 3-4-5 triangle then provides two 25 MY lengths that fit perfectly with the five-sides of the "back-to-back" 12-13-5 triangles. 

Copy of MRBB-COVERThe Quadrilateral and Geant appear in Alexander Thom's 1978 book Megalithic Remains in Britain and Brittany (Clarendon Oxford), who surveyed The Alignments and the network of menhirs, calling the Geant, menhir M. I have adapted his site plan to represent the Quadrilateral above but it is not clear where his plan came from. 

My brother and I came to survey the monument again in spring equinox 2010 after Robin had identified the midsummer solstice alignment from the Quadrilateral's sun gate, point P, at the previous summer solstice event. He recognised the signature 14 degree angle of a "lunation triangle" and tapes revealed the structure as being coded three inches to the day. However, my own work on day-inch counting was looking for an exemplar monument and it was known that a count over three years would automatically generate a megalithic yard length. This unbelievable good luck gave an exemplar monument for a count over three years that needed to survey the Quadrilateral in more detail.

After the survey I worked on the published survey document for about three months before moving on to working on possible simulators and then the Le Menec western cromlech and alignments, where simulators were transformed into circumpolar observatories. This year has been dominated by publishing analyses on this website based upon the key technologies responsible for the monuments, day-inch counting, metrological triangles and multiple squares, and circumpolar observatory circles; each exceeding the limitations of purely horizonal astronomy in a different way. 

Le Manio, Hanging on the Moon

On returning to Le Manio, this recent work is revising what can be understood about it. As a simple start for this introduction, the reader will notice that the northern kerb is angled relative to the southern kerb. This was thought (Thom MSBB) to be because the northern kerb formed part of an alignment to a stone L, near Le Menec, from which the northern minimum standstill  moonrise could be seen sitting upon this northern kerb. In the world of multiple squares therefore, the kerb defined the diagonal of a double square. But then, the question has always been there as to why the Quadrilateral was at its sharp angle to east, an explanation for which having been given by AAK based on the angle of the southern kerb as being that of a 12-13-5 triangle to east (22.62 degrees), the longest side of which ran down to Le Menec, so having provided an abstract geometrical backbone for the Le Menec and Kermario Alignments.  Perhaps for this reason, Howard Crowhurst had identified the two back-to-back 12-13-5 triangles to point J. Our next article will show this to have been a brilliant direction to take.

Whilst not perfect, the angle of a 12-13-5 triangle adds to a four square diagonal's angle (of Robin's lunation triangle) to arrive at the angle just short of a 3-4-5 triangle's acute angle, thus giving an explanation relative to east as a geometrical combination. This "bottom up" explanation can now be contrasted with a multiple square analysis working "top down", from the lunar minimum, as in Figure 2 below.

Copy of LeManio-Integration-13UNITS

Figure 2 A framework that explains the orientation of Le Manio using the double square diagonal of the moon along the northern kerb. The thirteen square diagonal angle exactly bridges between the angles of the northen and southern kerbs. Note the introduction of a new site plan drawn by Robin Heath which corresponds better to the actual stones and particularly in their width which was often exaggerated in Thom's plan.

The builders probably used a double square to align the northern kerb so as to emphasise that the northern kerb was between (distant) stone L to the west and the minimum standstill moon in the northeast. Meanwhile, the four square diagonal provided by stone R from P means that its base is three times twelve lunar months (lunations) long on its base so that a side length, then of three lunar months, can pack three thirteen square rectangles into the four square, with one left over.

Copy of DSC00126What is attractive about this explanation its lack of abstract components, for everything hangs on the moon and then the sun, except perhaps to explain the function of the three stones north of stone R that have a definite bearing of their own. The day inch counts for three lunar years and three solar years are now joined by three lunar years of thirteen lunar months and this can arc up to hit the important NOTCH found in the northern kerb (see right hand inset: this photo was taken from the notch looking south, on the sightline to Menhir Geant past the three solar year day-inch count at the end of stone Q'.