Models of Time within Henges and Circles

image: composite, see figure 1 below

Presenting important information clearly often requires the context be shown, within a greater whole. Map makers often provide an inset, showing a larger map at a smaller scaling (as below, of South America) within a detailed map (of Southern Mexico).

This map is shown in the context of South America with a yellow rectangle which is the part blown up in scale. The subject is the Quetzal birds range which corresponds well to the Olmec then Maya heartlands leading to the god named Quetzalcoatl or Feathered Serpent. (see chapter 8 of Heath, 2018.)

Megalithic astronomy generated maps of time periods, using lines, triangles, diameters and perimeters, in which units of measure represented one day to an inch or to a foot. To quantify these periods, alignments on the horizon pointing to sun and moon events were combined with time counting between these events,where days, accumulated as feet or inches per day, form a counted length. When one period was much longer than another, the shorter could be counted in feet per day and the smaller in inches per so that both counts could share the same monumental space. In this article we find the culture leading to megalithic astronomy and stone circles, previously building circular structures called henges, made of concentric banks and ditches.

Thornborough Henge

Britain’s Greatest Henge

A previous article about the Thornborough triple henge in North Yorkshire, looked at its likely metrology as a time-factored artifact. That henge consists of three henges, oriented rather like Orion’s belt of stars, but it in fact it pointed to the maximum standstill of the setting Moon on the north west horizon. Its central henge is of particular interest, in providing the astronomers with a firm day-to-day grasp of the major cycles of the Sun and Moon using multiple counts between diametrically opposite points on the inner rings. Through counting time: the most elusive of all the time periods, the rotation of the Moon’s nodes around the Ecliptic (responsible for eclipses) was counted in-between the north and south henges, as per the previous article.

A Henge is a circular structure with at least, a ditch and raised ring marking its limit. Thornborough’s three henges each had three distinct concentric rings, this being the norm in Yorkshire’s henges (see figure 1). And since these other henges are also of a similar size, this implies that both their size and design were shared and related to some kind of function.

The outer ring defines the space of a henge and we note the two inner rings display a given ratio to each other, of around twelve to nineteen*** units. In other words when one looks at these diameters as a ratio, the nearest simple integer ratio that fits is 12:19. Since the rings are quite thick, and hard to measure between clear datums,the significant time periods relating to the sun and moon form two groups, of around twelve months and nineteen years.

*** This ratio is very interesting since it can be normalised through division of the shared difference into each of the two numbers. 12/7 = 1.7143 which in feet is the Royal cubit whilst 19/7 = 2.7143 which is the megalithic yard

Figure 1 (right) the similarity in form and size of North Yorkshire’s henges and (left) the integer ratio to be found between the inner and middle rings in Thornborough’s central henge. [composite of sections of figures 3.18 and 6.4 of Harding. 2013]

Significance of 7, 12 & 19 found at Carnac

From surviving engraved art near Carnac in Brittany, one can read that the megalithic counting of time (by 3500-3200 BC) had evolved inches to count days and the megalithic yard of 19/7 feet (the overrun of three solar years over three lunar years when counted in day-inches). In Gavrinis’ stone C3 we see engravings using divisions of 12/7 inches, within an astronomical diagram. From the centre of stone C3 (figure 2), seven divisions (times 12/7 inches) show the (so-called) English foot as seven divisions of 12/7 inches, running downwards from the centre. Also shown are 5 extra divisions, culminating in a phallic design, to reach a radius of 12/7 feet, the (so-called) Royal foot of the Egyptians. The stone C3 appears as a whole to have been composed within a circular framework of 19/7 feet, the (so-called) astronomic megalithic yard.

Figure 2 Stone C3 of Gavrinis annotated as to its metrology. [adapted from figure 5.10 of Heath. 2014]

We therefore found at Gavrinis stone C3, two distinct measures within its engraved art, measures related by the ratio 12 to 19, numerators of the Royal cubit and megalithic yard over a common denominator of seven. My brother and I have already demonstrated how these measures emerged 4 Km west, at Carnac, through the astronomical invariance revealed by counting three years in day-inches. When lunar months per megalithic yard are counted, instead of day-inches, the three periods of eclipse year, lunar year and solar year, can be seen to form 19 year cycles.  The foot naturally emerged from the fact that the solar year contains 12 plus 7/19 lunar months (equaling 12.368) so that a megalithic yard of 19/7 feet cancels with the 7/19 lunar months to leave an excess per year of one foot. In feet, the solar year is then 12 megalithic yards plus one foot, or 33.585 feet, and the lunar year of 12 lunar months 32.585 feet, the number of inches in a single megalithic yard.

  • We know that the Saros period is made up of 19 Eclipse years and this is because 19 x 14/19 = 14 which plus (11 x 19) equals the 223 lunar months of the Saros.
  • We also know that the Metonic period is made up of 19 solar years and this because 19 x 7/19 = 7 which plus (12 x 19) equals the 235 lunar months of the Metonic

This may seem impossibly fractional for a culture without decimal or similar arithmetic, but it is the measures themselves that enable counting to evolve natural denominators which divide into the found time periods in a simple and elegant way.

The Yorkshire Henge Design

I believe the builders of the Yorkshire henges (figure 1), in building two rings in the ratio 12 to 19 were referencing (a) the three different years which are all about twelve months long and (b) the Saros and Metonic periods which take nineteen of the eclipse and solar years, respectively, to complete.

Figure 3 Central Henge of Thornborough with 12 to 19 ratio employing a scale of feet to inches for days. The two sets of concentric red circles are (smaller) the eclipse, lunar and solar years and (larger) the Saros period, 19 lunar years and the Metonic period [adapted from Figure 3.18 of Harding. 2013.]

By counting the shorter year periods as a diameter in feet and the longer periods of 19 years in inches per day, made it possible for the eclipse, lunar and solar years (in feet per day) to be efficiently located within their anniversaries with the moon over nineteen years (in inches per day) resulting in the single compact henge monuments we find. These time periods, as diameters, could be used for continuous counting of years and anniversaries, in a calendrical fashion: major time periods would be seen as counts in progress so that at a given moment, each would be at a different stage of completion. Astronomers would learn many things such as, that the Metonic has a near relationship to the Saros in being 20 eclipse years long relative to the Saros’ 19 eclipse year duration.

Counting in Lunar Months

Once the commensurability of the lunar month to larger cycles was established, that the Saros was 223 lunar months long and the Metonic 235, later monuments could employ a tally of full moons between eclipses (see Stoupe Brow) within a month counting scheme, or count lunar months per megalithic yard (exactly 32/29 larger than 29.53 day-inches) to form lengths used geometrically within monuments. The advantage of a counting tally is its small size and portability.


Harding, Jan et al. 2013. Cult, Religion, and Pilgrimage: Archaeological Investigations Thornborough. Council for British Archaeology: York.

Heath, Richard.

  • 2014. Sacred Number and the Lords of Time. Inner Traditions: Rochester.
  • 2018. The Harmonic Origins of the World. Inner Traditions: Rochester.

Heath, Robin. 1998. Sun, Moon and Stonehenge. Bluestone Press: Wales.