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KRONOS Vol VIII, No. 2
A Calendric View Of Stonehenge
Copyright (c) 1982 by Alban Wall
In an earlier paper,(1) I presented evidence indicating that the Aubrey circle of holes at Stonehenge was designed to be used as a solar calendar. The present article can be considered an extension of that hypothesis which is here made to include the remaining components of the structure. It will be shown that the functional correlation of these remaining components, in conjunction with the previously discussed Aubrey Circle, combine to form an amazing and sophisticated calendrical device which is more accurate in its basic simplicity than anything that Hawkins and Hoyle ever envisioned.
There is important calendrical significance in the fact that 235 lunar months, generally referred to as lunations, which constitute the time encompassed in one full cycle of lunar phases, are equal - within a few hours - to 19 solar years.
The knowledge of this celestial phenomenon enabled various peoples in the early history of mankind to devise chronological systems which thus reconciled solar and lunar times. In those systems, months were counted as of 29 or 30 days alternately, an arrangement that averaged out quite close to the actual length of a lunation.
A year of 12 lunar months falls nearly 11 days short of the solar year and, since the latter determines the return of the seasons, there was need to adjust the calendar to the solar year. This was accomplished by the intercalation of an additional month 7 times within the 19-year period in such a manner that the full cycle consisted of 125 thirty-day months and 110 twenty-nine-day months.
In the following pages I will describe how the various components of the Stonehenge structure, functioning together perfectly, formed a luni-solar calendar based on this 19-solar year - 235 lunar month – co-ordinated cycle. The reader will come to realize that the claim of Hecateus was not merely an imaginative piece of ancient mythology, but a firm historical fact.
The Stonehenge monument, as I see it, was a device composed of stationary as well as interrelated movable components, and thus qualifies as a machine. The stationary elements consisted of the following (see Drawing #1):
[*!* Image] Drawing No. 1. The Stationary Components of the Stonehenge 19-Year Luni-Solar Calendar (not to scale).
The moving, or movable, components were:
1. Aubrey Circle . This component is used to track the movements of the Sun. It forms a dial around which marker-stone S is advanced at the rate of 2 holes per day. The marker will travel around the circle once every 28 days (13 times in 1 year). It will be at hole #56 every year on the day of summer solstice at the same time that the Sun rises at that point of the horizon. The marker will move around the circle exactly 247 times during the 19-year cycle, ticking off 6,940 days in the process. These twenty-eight-day divisions - 13 per year - can be considered as solar "months" which will interrelate with the lunar months. At the midpoint of the cycle, that is after 9½ years, the marker will rest at hole #28 on the same day that the Sun sets at that point of the horizon, which occurs on the day of winter solstice.
2. Sarsen Circle . This component is used to track the movements of the Moon. It forms a dial around which marker-stone M is advanced at the rate of 1 arch per day. However, in order to keep in step with lunations, which average out at about 29½ days, the markerstone is made to skip 1 arch every other revolution, thus completing two circuits in 59 instead of 60 days. When advanced in this manner, the marker will make exactly 235 revolutions of the Sarsen Circle during the span of the 19-year cycle ticking off, as did the Sun marker-stone, 6,940 days in the process. In 9½ years it will make 117.5 revolutions.
Since the movement of the marker-stone around the Sarsen Circle is so regulated as to keep it in continuous synchronization with the phases of the Moon during each lunation, the position of the marker on the circle will also accurately indicate the lunar phases at all times. For example, whenever the stone rests at arch #30, the Moon will be new. When at arch #7, or, more precisely, the megalith separating #7 from #8, the Moon will be at first quarter and waxing. At arch #15, the Moon will be full. At #22, or the megalith separating that from #23, the Moon will be in its last quarter and waning.
3. The Trilithons . These 5 components are arranged symmetrically within the Sarsen Circle and, in my opinion, they were intended to be used in conjunction with the latter. They seem to have been designed and set in position to indicate the Moon's phases in a manner that will be described in detail below.
4. The Bluestone Horseshoe . In this component, a marker-stone, YR, is moved around the horseshoe formation 1 stone per year. This arrangement serves as a year indicator within the 19-year cycle.
5. The Heel Stone . This element marks the approximate point of summer solstice sunrise. It was, in my opinion, used to mark the beginning and the end of each 19-year cycle.
Over the years, the principal components of the Stonehenge structure have acquired names which either indicate their shape and pattern, the materials of which they are composed, or, as in the case of the Aubrey Holes, the name of the antiquarian who rediscovered them in modern times. For purposes of this paper, and in order that the reader may more easily follow the operation of the device as I will explain it, I have assigned additional qualifications to these elements in order to graphically reflect their functions in the calendar. The changes in nomenclature are as follows:
Drawing #1 is a schematic rendering of the above components as they existed in the original design of the structure. Note that the elements, with the exception of the Heel Stone Sunrise Marker, are concentric. As will be seen, this concentricity was not just a frivolous feature but a deliberate arrangement intended to serve as a factor vital to the successful operation of the calendar.
Since the 19-year cycle represents periodic coordinations of the movements of the Sun and the Moon, devices set up to track these movements ought logically to reflect such celestial coordinations. The Aubrey Sun and Sarsen Moon Circles in the plan of Stonehenge perform this function admirably.
As already stated, what appears to be the axis line of the structure, around which the various components are symmetrically oriented, is the line that runs from the center of the monument through the center of the Sarsen Moon Circle arch #30, out through Aubrey Sun Circle hole #56, to the horizon. It is this line that marks the approximate azimuth of summer-solstice sunrise. Note that arch #30 and hole #56 are in conjunction, that is to say, in line with each other and with the center of the monument. In the explanation of the operation of the calendric device that follows, it is these points that will be considered as the starting and ending ones of the 2 dial systems, solar and lunar. This is much the same way that the numeral 12 performs its function in a modern clock. On this basis, the Aubrey Sun Circle is divided into quadrants by holes #56, 14, 28, and 42. Correspondingly, the Sarsen Moon Circle is divided into quadrants by arch #30, the megalith dividing arch #7 from #8, arch #15, and the megalith between arches #22 and #23. These 4 points in each circle are in conjunction respectively in the following manner:
Hole #56 with arch #30. Hole #14 with megalith #7-8.
Hole #28 with arch #15. Hole #42 with megalith #22-23.
Since hole #56 of the Aubrey Sun Circle corresponds to 12 o'clock on a modern timepiece, it can be seen that holes #14, 28, and 42 correspond to 3, 6, and 9 o'clock respectively.
Similarly, since arch #30 represents 12 o'clock on the Sarsen Moon Circle, arches and megaliths #7-8, 15, and 22-23 correspond also to 3, 6, and 9 o'clock respectively.
The actual movements of the Sun and the Moon over the span of the 19-year cycle will be reconciled in the calendric device at the 4 above-mentioned points - that is, when the Sun and Moon markerstones are in conjunction at these 4 positions.
Just as the Sun and Moon marker-stones divide their respective circles into quadrants, so too do they divide the 19-year cycle itself into quarters when they are in conjunction at these 4 positions on certain days. This information can be tabulated as follows:
Not only is the 19-year cycle divided into quarters by the 4 conjunction points, so also are the solar year, the lunar month, and the 235 lunations of the full cycle (58-3/4 lunations per quarter). These facts are clearly evident in the table and are additionally graphically depicted in Drawing #1.
With its system of "dials" and moving "hands", the Stonehenge "astronomers" would have been able to "read" their chronological instrument as easily as we read a clock, not only at the 4 prominently highlighted quarter points, but at any time during the complete 19-year cycle as well. Consider: The various components of the calendar continuously provide the following chronometric information:
Besides all this, there might also be as yet undiscovered, undeciphered, or obliterated components at the site which might have additionally indicated time divisions larger than the 19-year cycle itself, such as the number of the cycle.
A logical operation of the device would have been as follows:
At a specific concurrence of two celestial events – summer-solstice sunrise and new moon - the 3 markers, S, M, and YR, are set in position as indicated in Drawing #2: S at Aubrey Sun Circle Hole #56, M at Sarsen Moon Circle arch #30, and YR at Bluestone Year Horseshoe stone # 1.(3) In order that this arrangement is not thought of as being haphazard, it should be noted that, at this point, the rising Sun, the rising new Moon, marker S and marker M are all aligned on the same azimuth bearing. This is the start of the 19-year cycle. From here on, marker S is advanced clockwise 2 holes per day while marker M is advanced in the same direction one arch (or one megalith) per day. Allowing for the necessary intercalations explained in my earlier paper,(4) marker S will make 13 turns around the Aubrey Sun Circle and be back at hole #56 at the end of each solar year. This means, of course, that it will be at the same hole #56 at the end of the 19-year cycle.
With necessary intercalations, marker M will move around the Sarsen Moon Circle on the average of once every 29½ days, being at arch #30 at the end of each lunation and also at the end of the 19 year cycle.
[*!* Image] Drawing No. 2. Alignment of the 3 Marker Stones with the Rising Sun and Rising New Moon at the Start of the 19-Year Calendar Cycle.
Needless to say, since there are exactly 19 stones in the Bluestone Year Horseshoe, marker YR is moved around it at the rate of one stone per year, thus also completing its circuit in 19 years.
Because the 5 moving elements advance along their respective paths at different rates of speed, the positions of all 5 relative to each other at any given moment will, with one exception, present a scattered pattern. Yet remarkably, as a simple calculation will show, after the passage of almost exactly 19 years (6,940 days or 235 lunar months), the Sun, the new Moon, and markers S, M, and YR will all be back at their original starting positions – the rising Sun and new Moon close to the Heel Stone Sunrise Marker, marker S at hole #56, marker M at arch #30, and marker YR at Bluestone Year Horseshoe stone #1 respectively. Once again, with the obvious exception of marker YR, these moving components will be aligned near the same azimuth bearing. Moreover, and most importantly, this will occur on the same day the day of summer solstice. At no other time will the markers be at these specific positions on the same day as each other anywhere in between. This correlation of the three markers in the Stonehenge calendar is as close a reflection of the cyclic concordance that takes place in nature between the movements of the Sun and the Moon as one can hope to achieve through artificial means. The phenomenon can be summed up succinctly:
At the midpoint of the 19-year cycle (see Drawing #3) i.e., after 91/2 years, the 3 markers, S, M, and YR, will be at the 6 o'clock point of their respective dials: S at hole #28, M at arch #15, and YR halfway between stones #9 and 10 of the Bluestone Year Horseshoe. Whereas the original alignment at the start of the cycle was effected on the day of summer solstice, the midpoint alignment will take place on the day of winter solstice. At this time the Sun will actually set adjacent to hole #28 where the Sun marker-stone (S) rests. This constitutes a visual correlation. At this point in the cycle the Moon marker (M) sits at arch # 15, at the exact halfway point in a lunation and also at the halfway point of the total 235 lunations in the overall cycle. This indicates that the Moon is in its full phase, which in fact it will be.
[*!* Image] Drawing No. 3. Alignment of the 3 Marker Stones with the Setting Sun and Rising Full Moon at the Start of the 19-Year Calendar Cycle.
It is important to note that, at the commencement of the 19-year cycle, the declinations of the Sun and the Moon are of nearly the same value (within a degree or so). Sunrise and Moonrise will therefore occur near the same place on the horizon, i.e., close to the Heel Stone Sunrise Marker. Needless to say, being new, the Moon will at this time be invisible.
At the midpoint of the cycle, 9½ solar years will have elapsed and the Sun will be in its winter solstice position. During the same period, 117½ lunar months (lunations) will also have elapsed and the Moon will therefore be at full phase. This means that the Sun and the Moon will again have nearly the same, but opposite, declination values south for the Sun, north for the Moon. It is interesting to note that on this day the Sun, as viewed from the center of the monument, will set through the great trilithon C while, about the same time, the full Moon will rise in the Heel Stone Sunrise sector (A' B' in Drawing #3), directly opposite the setting Sun, thus providing, at the midpoint of the cycle, dramatic confirmation of the reliability of the Stonehenge calendar.
So far, I have dealt with the Sun and Moon correlation at the start and midpoint of each 19-year cycle. At those 2 times the Sun and Moon markers will be in conjunction at hole #56/Arch #30 and hole #28/Arch #15 respectively. The two remaining points of conjunction of Sun and Moon markers to be considered are those which occur at hole #14/trilithon-arch #7½ and hole #42/trilithon-arch #22½. These conjunctions take place at the 3/4 and 1/4 points of the 19-year cycle respectively, the first at the time of vernal equinox and the second at the time of autumnal equinox. In each instance the Sun will rise due east and set due west and, also in each instance, a half-moon will be visible. That is to say, the Moon will be at first quarter and waxing in the first case, and at last quarter and waning in the second.
In Drawings #2 and 3, I have included the actual appearance of the Moon for each 5 days of its lunation cycle. When the Moon-Stone, M, is at arch #5 (day 5), the Moon will be crescent and waxing. When the Moon-Stone is at Arch #10 (day 10), the Moon will be gibbous and waxing. And so on through the cycle. As can be seen in the drawings, the orientation of the Moon Phase Trilithons is directed to the actual azimuth of the rising Sun/rising new Moon conjunction which occurs at summer solstice at the start of every 19-year cycle. By the same token, the orientation of the same Trilithons is also directed to the actual azimuths of rising full Moon/setting Sun opposition at winter solstice, a circumstance which signals the midpoint of each 19-year cycle. This orientation of the Trilithons dramatically highlights the chronological importance that attaches to these two time-points in the cycle. The orientation is not directed to the actual azimuths of conjunction or opposition of Sun and Moon at any other time. Nevertheless, because the movement of the Moon marker around the Sarsen Moon Circle keeps in step with the phases throughout each lunation, the position of the Moon marker-stone on the Sarsen Moon Circle is thus an exact indicator of what the phase of the Moon actually is, whether visible or not, on any particular day.
Note now the alignment of the 5 Trilithons with the Sarsen Moon Circle arches. Each Trilithon is exactly aligned with the center of the monument and one of those arches that divide the lunar month into sixths. This cannot be a coincidence. In fact it betokens a certain ingenious and intriguing feature of the Trilithons that no other investigator, to my knowledge, has dealt with or incorporated into the Stonehenge scheme – and that is the variation in their elevations. It is significant that, starting with A, the Trilithons increase in height through C and decrease again to E. This fact, in conjunction with the specific Sarsen arches we have just analyzed, is a clear indication that the 5 Trilithons were hewed to their specific heights and erected in their specific positions precisely to point to, and symbolize, the 5 major phases (six with the new Moon) in the waxing and waning of the lunar orb. For a fuller understanding of this phenomenon, I ask the reader to follow the cycle as indicated in Drawing #2.
On the fifth day, the Moon is a mere waxing crescent and Trilithon A, which lines up with the fifth Sarsen Circle arch, is about five feet shorter than Trilithon B. Trilithon B, in line with the tenth-day Sarsen arch, indicates the Moon when it is gibbous and still waxing. Appropriately, the tallest Trilithon of the five, C, aligns with the fifteenth-day Sarsen Arch when the Moon shines forth in all its fullness and splendor. As the lunar orb wanes again to gibbous, and is indicated at Sarsen Arch #20 (on day 20) by the Moon marker-stone M, Trilithon D, which lines up with that particular arch, is again of lesser height. The waning crescent Moon, at Arch #25 (on day 25), is symbolized by Trilithon E which, in its turn, is again shorter than Trilithon D. Finally, we see that there is no trilithon at all in line with Sarsen Arch #30 (day 30) for the simple reason that this Arch represents the point in the lunar cycle when the Moon is new and therefore totally invisible.
The practice of indicating lunar phases directly within the calendric device is perpetuated to this very day. Many modern calendars depict the Moon's phases within the date blocks on which they occur.
In the foregoing pages, I have characterized the structure on Salisbury Plain as an integrated calendar. I have done this on the basis that the elements of which Stonehenge is composed interrelate in a fundamental and functional manner, each being dependent upon the others. Remove any of the stationary or moving components and the entire machine is disrupted. Without the Aubrey Sun Circle, how could the ancients have kept track of the solar year? Remove the Sarsen Moon Circle and how could the passage of the lunar months be noted? Take away the Trilithons and how could the phases of the Moon have been indicated? And although the builders of Stonehenge could have kept track of the 19-year cycle by other means, does not the Bluestone Horseshoe, which serves this function, enhance the monument's total completeness?
It is on the strength of this obvious fundamental concordance, which interrelates these various Stonehenge elements, that I emphatically state the following conviction: That there were not, as generally claimed,(5) great time gaps separating the construction of each of the monument's basic components. The interdependency of all the components clearly indicates that the complete and final design of the structure must have been conceived at the very outset. In a series of subsequent papers, I hope to adduce additional evidence in support of this conviction.
REFERENCES1. A.Wall, "The Aubrey Holes of Stonehenge," KRONOS IV: I (Fall 1978), pp. 29-44 and IV: 2 (Winter 1978), pp. 80-97.
2. S.Piggott, The Druids (N.Y.,1975), pp.115-116 (emphasis added).
3. NOTE by D. Cardona: It is a pity that these various components were numbered at a time when their significance was largely unknown. If Wall's theory is ever accepted by archaeologists and archaeoastronomers, it would be hoped that the numbering of the Stonehenge components would be changed. Thus, Aubrey Hole #56, for instance, would be renumbered Aubrey Hole #1 and Sarsen Arch #30 changed to Sarsen Arch #1. These changes would then conform to Bluestone #l and the beginning of the 19-year cycle.
4. A.Wall, op. cit., KRONOS IV:I (Fall 1978), p. 35.
5. See, for instance, G. Hawkins, Beyond Stonehenge (N,Y., 1973), p. 24.