By Dr. Charles Scribner
© Copyright 2001 Charles Scribner - All rights reserved
Updated 19 October 2001

Edited by Michael O'Callaghan


How Knowth worked is pretty damned obvious but it requires developing the competence in Astronomy one of their 14 year olds would have had, which starts with the ability to answer the question his 12 year old sister asked him in November: "when do we leave for the celebrations at New Grange?" ...which happen each year at the time of the full moon nearest the winter solstice. Very simple answer: "When the first quarter moon passes under Aldebaran", i.e. 7 some days to the midwinter full moon which always happens, circa 3000 BCE, when the moon is passing under Chertan in Leo.


The passage at Newgrange is still a statement that the winter solstice was a particularly important time of year for the peoples who built the three mounds along the river Boyne.

Knowth, which was built around 3300 BCE, contains 2 passages: (A) the 118 foot long Eastern passage (which Dúchas and their supervising archeologist, George Eogan, quite bizarrely chose to block in order to restore a structure built by monks who squatted there around 600 CE - an act for which they have not been held accountable), and (B) the bent Western passage.

The goals of these passages on the horizons tell us that the builders were interested in certain sunrises and sunsets around the times of the two equinoxes. To analyze their intentions, one must go back to 3300 BCE, when both the calendar dates of spring, fall, summer, and winter –and the lengths of the seasons– were not the same as they are now.

Cross-quarter days and seasons in 3300 BCE:

spring equinox:

April 17

summer solstice:

July 20

fall equinox:

Oct. 17

winter solstice:

Jan 14


94 days


89 days


89 days


93 days

The surveys of the passages made by Professor Eogan (which were confirmed by Professor Ray and Professor Prendergast before the final belsening of the Eastern passage) show the following:


The central axis of the Eastern passage pointed to the place the sun rose on 23 April. This date corresponded, in 3300 BCE, to six days after their spring equinox (i.e. 17 April + 6 days).

[COMMENT: I notice you wrote "pointed to the place the sun rose" in the past tense . Is this what you really mean, or would it be better to write "points to the place where the sun rises" on 23 April?]

Why the peculiar interest in April 23, their spring equinox + 6 days?

Their spring – 17 April to 20 July – was 94 days long.

The timespan from 23 April to the summer solstice, is 88 days, i.e. 3 synodic months or 3 same moon phases. So whatever phase of the moon is visible on 23 April will re-occur on the following summer solstice.

[COMMENT: the astronomical term "synodic months" is confusing to the intelligent layman (like myself!): so just to clarify, I presume it means "from same moon phase to same moon phase". Is this correct?]

Again, the timespan from the chosen 23 April to the fall equinox (17 October) is 177 days. This corresponds to 6 synodic months, i.e. half of the archaic formal period of 12 synodic months (354 days) – called the pure lunar year – which many primitive cultures used as the basis of their calendar. So whatever phase of the moon you see on 23 April will repeat on the fall equinox.

In other words, if the moon is full on 23 April, it will also be full on the summer solstice and the fall equinox. The 89 day duration of the ancient fall season take one to a full moon on the day before the winter solstice. Alternatively, if the moon phase which belongs to a given 23 April is a first quarter moon, the moon will be full 7 days after the summer solstice and fall equinox and 6 days after the winter solstice.


The Western passage is bent. Its older, inner portion has a different orientation to its newer outer portion. The alignments of both portions served similar predictive functions as that of the Eastern passage.

Surveys show that the inner (and older) portion of the Western passage is oriented to the position where the sun sets on the horison on 27 April (April 27.5). This corresponded, in 3300 BCE, to 10.5 days after their spring equinox (i.e. 17 April + 10.5 days). The significance of this date is that if a full moon is seen that evening, the moon will also be full on the evening before the next spring equinox – a date which occurs one pure lunar year (i.e. 12 synodic months or 354 days calendar time) in the future.

The central axis of the outer (and more recent) portion of the Western passage is oriented to the position of the sunset on 29 March (March 29.5). This date corresponded, in 3300 BCE, to 18.5 days before their spring equinox (i.e. 17 April - 18.5 days).

It follows that the span of time from 29.5 March to 17 April 17 in the following year is 365 days + 18.5 days = 383.5 days. The significance of this timespan is that it almost exactly corresponds to 13 synodic months, i.e. 383.8978 days.

This correspondence strongly suggests that one of the reasons for re-orienting the Western passage was to provide an additional synodic month's worth of ability to predict the phase of the moon on the spring equinox a year in the future:

e.g. if –when the beam of the setting sun enters the Western passage (on March 29) in a given year– it is 2 days before a full moon, then the spring equinox of the following year will also occur 2 days before a full moon.

Another reason for re-orienting the Western passage, has to do with the second day of the year in which this passage catches the rays of the setting sun: November 4.5 (which corresponded, in 3300 BCE to 18.5 days after their fall equinox), and the timespan between this date and the next fall equinox, i.e. 365 days minus 18.5 days = 346.5 days. The significance of this timespan will be dealt with in a forthcoming paper after other parameters are established.


These findings suggest that the builders of the Brú na Boinne complex were already numerate and knew the lengths of the synodic month and the tropical year.

This claim is still denied by Aubrey Burl and Clive Ruggles (Professor of Archaeoastronomy at the University of Leicester and President of ISAAC - the International Society for Astronomy in Culture), who have also neglected the available evidence for the numeracy of cultures from the field of linguistics.

Although the pioneering astronomical discoveries of the builders of the Brú na Boinne complex remain unrecognised by many established archaeologists and astronomers, no-one can deny their achievements in the fields of architecture and engineering: the ability to plan and build three large chambered passage mounds (and dozens of smaller ones) over a span of several centuries, the living cooperating with the dead across ten generations, and [ which later on, at other places enabled communities to move ] the transportation of massive stones – each weighing many tons – over long distances, and their arrangment on the ground in geometric patterns.

Many cultures whose material achievements were far inferior to the Brú na Boinne builders had languages containing count words which embody correct arithmetic, addition and multiplication, and words for very large precise numbers in the thousands of thousands range, as opposed to words implying only "very large" but still undefined quantities.

[COMMENT: this above paragraph makes a very good inference: it would be useful if you can identify a few examples of such cultures, or provide a reference to one or more books, papers or authors which provide more information to substantiate your observation. Also: are you thinking of other pre-historic cultures here, or of indigenous peoples cultures visited by anthropologists in the 20th century? If the latter, then we should change "had languages" to "have languages". ]

When the Indo-European languages first began to be written phonetically, the word for 100 –one hundred– not some vague "more more", had the two pronunciations: satem and centum, which are still used to divide the family of Indo-European languages into its Eastern and Western branches. A paper in British Archeology a few years back noted how count numbers derived from both p and q Celtic continued to be employed by shepherds and drovers in various areas of England up into the 1930s.

[COMMENT: the above comment about Indo-European languages is very interesting, but I don't see its relevance in advancing your argument that since the languages of technologically primitive peoples often have high numeracy capability, it is therefore likely that the more technologically advanced builders of Knowth had at least equivalent numeracy. If there is no relevance, it might be better to remove this paragraph.]

In the case of Native American peoples, the ability to make pottery does not seem to be a prerequisite for a language that has accurate large number systems.

[COMMENT: I take this to mean that some Native Americans had good numeracy without the ability to make pottery - is this correct? If so, it would again be useful to provide some examples or scholarly sources here.]

Calendar petroglyphs on kerbstone SW22 at Knowth © 1999 Anthony Murphy


A drawing of kerbstone SW 22, made by Martin Brennan in 1980 appears on Page 129 of Ruggles' book "Astronomy in Ancient Britain and Ireland."

[COMMENT: would it not be more appropriate – in solidarity with our fellow astroarchaologist – to mention the page number on which the drawing appears in "The Stars and the Stones" rather than in Ruggles' book?]

Brennan concluded that SW 22 had the potential to be a synodic month calendar.

The bottom center is occupied by a spiral, significantly a double spiral, there being a general consensus that spirals are solar symbols. Going clockwise, coming out of the spiral or sun symbol, there are 29 moon symbols: i.e. 11 initial crescents, 7 circles opposite the double spiral or sun, and a final 11 crescents leading back into the double spiral. The layout of the whole is new crescents in the East, through the fuller moons in the centre, to the aging crescents in the West.

Synodic month calendars are made of short synodic months of 29 days, the 29 moons, and long synodic months of 30 days, the 29 moons + 1 of the spirals. One of the interesting qualities of this icon is the lack of quarter moons.

There are 11 initial crescents, 7 circles, and 11 final crescents.

12 synodic months are 354 days, i.e. 6 calendar synodic months of 29 days alternating with 6 calendar synodic months of 30 days.

Let one lunar year start and end with the spiral. The next 11 crescents take one to 354 days + 11 days, day 365, the recognition that single lunar years were 11 days less than single tropical years.

[COMMENT: again, I presume "tropical year" means solar year: is this correct?]

A count system for the tropical year is also present. The 29 moons and 1 of the spirals give the number, 30. The 29 moons and both spirals give the number 31. The common tropical year, 365 days, can be made of (7 x 30 days) + (5 x 31 days). Leap years are (6 x 30 days) + (6 x 31 days).

(To be continued..... )

It is also necessary to accept what happened between the archaeologists and archaeoastronomers 1975 on and what actually happened at Knowth rather than invent phantasies. The original sin was the success, popular and financial, of Newgrange, which created an opening for reconstruction archaeology, a real perversion, and the decision to theme park the site, preserving the souterrain because it creates a "cross section of Irish history" 3300 BC to 600 AD. Blocking the Eastern passage was an acceptable part of that decision because, starting c 1975, people like Ruggles, the new archaeoastronomers, convinced the dirt archaeologists that real astronomy was beyond their abilities and should be left to the experts. At the same time, the dirt archaeologists became aware that paying too much attention to the ideas of the Thoms and others could endanger their careers. For the most recent exposition of threats, by Ruggles and a tame dirt archaeologist by the name of Barrett, see the character assassination of Euan Mackie that appeared last year in "Antiquity". There is no conflict between the archaeologists and the current archaeoastronomers.

[COMMENT: The meaning of your final sentence "there is no conflict between the archaeologists and the current achaeoastronomers" is not clear, in the context of the preceding paragraph, since Ruggles is alive, and you just implied that he is a fool. Do you mean that there is no conflict because they both subscribe to the same ignorance? ]


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Updated 20 October 2001
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