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extreme point is very difficult. At midsummer the point of sunrise stops moving north and starts to move south again. The effect is that the sun seems to come up at about the same place for several days in succession around the solstice before moving off again at gathering speed towards the equinoctial point. Thus the notorious phenomenon of the midsummer sun rising over the Heel stone at Stonehenge when viewed through the great trilithon is impressive only when one knows the date of midsummer anyway. If our modern Druids were deprived of their calendars and lost count of the days they would find it hard to decide which of several equally awesome sunrises over the Heel stone around June 21st was in fact the midsummer one. This is a very important point as will be seen shortly. How could midsummer sunrise be predicted ? involves an altogether higher order of intelligence and reasoning power. Two main points may be made about the whole concept of Neolithic man as an astronomer, one general and one particular. The first is that, assuming that he was concerned with marking out an accurate calendar, the presumed lack of equipment other than stones, posts and ropes must mean that to get any sort of accuracy his instruments would have had to have been very large and therefore horizontal on the ground. It is perfectly possible to define points on the horizon to within a 10th of a degree of arc with a pair of sticks 100 ft. apart. The particular point is that the defining of a solstice (extreme northerly or southerly sunrise or sunset) by watching the phenomenon and sighting a pair of stones or posts at the 280 Hawkins' theories about Stonehenge concern these two separate astronomical problems; he supposes Neolithic man to have attempted the defining of alignments with sun and moon phenomena and the observation and prediction of eclipses. They concern two separate structures, the Late Neolithic henge Stonehenge I and the unique Early Bronze Age sarsen construction Stonehenge III. The double bluestone circle of Stonehenge II is difficult to use for theorizing because it is known from relatively few stone holes. Although Stonehenge I was structurally least impressive, having only a few monoliths, it was, he suggests, by far the most sophisticated: the sarsen circle and trilithons are claimed only to indicate alignments to solstices, equinoxes and moon risings and settings. The theory that some of the stones and stone-holes of Stonehenge I were aligned towards significant astronomical points has been challenged for two main reasons—first that the statistical evidence used by Hawkins to prove the claim is invalid and, second, that he has used later features from Stonehenge II to bolster the argument. The most trenchant criticisms have been made by Professor Atkinson in 'Moonshine on Stonehenge' in Antiquity 1966 in which he showed that Hawkins statistics were wrong and that the socalled alignments between the stones were too inaccurate and could equally be the result of chance. Professor Hoyle, also writing in Antiquity, accepted these criticisms and was the first in the current controversy to point out that it was impossible, for reasons discussed earlier, to define the time of a solstice accurately by aiming the markers directly at the point of midsummer sunrise. The only way that the date of a solstitial sunrise or sunset—at midsummer or midwinter—can be fixed precisely is by aiming the pair of marker stones a degree or two inside the extreme
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Was Stonehenge a prehistoric computor? if so, which Stonehenge? point of rising or setting. Then the dawn or sunset occurs over the far stone twice—just before and just after the solstice—and while its position is still perceptibly moving; the date of the solstice itself can then be obtained with great accuracy by halving the interval between the two observations. Hoyle then tested Hawkin's alignments to see if they could be explained in this way, by being directed just inside the extreme positions. He found that, this time, the statistics positively favoured this view: there was only a 1 in 1,000 chance that such alignments could have occurred by chance. If the original alignments themselves are accepted as genuine ones between contemporary stones where the angle between extreme summer sunrise/ winter sunset and extreme winter moonset/summer moonrise was 90 degrees. If the Station Stones were set out in Phase II it would suggest that the advantage of the site in this respect was realised secondarily. If the original site was chosen with the Station Stone rectangle in mind then these positions should have been set out in Stage I as Hawkins believes. In this case though it is hard to understand why the Station Stone diagonals miss the centre of Stonehenge I but coincide with that of III. — an assumption on which everything obviously depends—Hoyle's observations would seem to provide better evidence for Hawkins' views than did the author himself. It certainly makes the technique of observation comprehensible in practical Neolithic terms. What were the Station Stones used for ? Concerning the alignments claimed for the sarsen circle and trilithons of Stonehenge III, Atkinson showed that the statistics offered to support them were even more unconvincing. This is perhaps hardly surprising when one considers that accuracy is scarcely possible when the 'foresights' are all wide lintelled archways, and never single stones. Also the bluestone settings put up inside the sarsen circle in Phases IIIb and IIIc would surely have hindered observations from the centre. Altogether Stonehenge III is quite unconvincing as any sort of astronomical instrument. However the great majority of the alignments for Stonehenge I involve the four Station Stones which stand on the circle of the Aubrey holes (only two of them are still on the site: the sockets of the other two have been located). They formed a rectangle about 105 x 260 ft. which is geometrically linked to the main sarsen circle of Stonehenge IIIa: the diagonals of the rectangle cross at the centre of this circle. Moreover this centre is about 3 ft. S.W. of the common centre of the ditch, bank and Aubrey holes of Stonehenge I. The position of the Station Stones, though perhaps not the stones themselves, could have been established with the bluestone circle in Stage II : this appears to have the same alignment as IIIa. Though this does not prove that the Station Stone rectangle was not of period I it seems unlikely in view of the close link between the diagonals and the circle centre of period III. However there is more to the Station Stones than surveyors' points to establish the centre of Stonehenge II or III. The short sides of the rectangle point to the extreme northerly and southerly positions of the sun's rising and setting respectively, the long sides to the equivalent lunar positions. The latitude where the angle between these alignments is 90 degrees and will thus permit a rectangle as opposed to a parallelogram to be formed of stones set up to mark them is limited to between about 30 miles north and south of Stone¬ hengle: further north or south the quadrilateral will become progressively more diamond-shaped. This could suggest that Stonehenge was originally sited deliberately at a suitable place in southern England Could eclipses be predicted ? The other sophisticated activity which Hawkins suggests was carried on at Stonehenge I was the observation and prediction of eclipses and it involves two suggestions, one plausible and likely and the other possible but unverified. The likely one is that the Heel stone was an indicator of winter eclipses of sun and moon. By using retrospective calculations Hawkins found that, in the second millennium B.C., whenever the full moon nearest to the winter solstice rose over the Heel stone (as seen from the centre of the henge) an eclipse of the sun or moon always followed. Only half these eclipses were visible from southern England, however. Also Hawkins' diagram shows that some eclipses occurred when the moon rose up to 3 degrees to the right or left of the apex of the stone so that the hypothetical Neolithic astronomer would have had a difficult task if this was his only method of foreseeing eclipses. He would have had to guess whether it was the moon or sun which was to be eclipsed and whether the event would be visible from Stonehenge. Also he would inevitably have missed a few which occurred even though the moon rose some way off the Heel stone, as well as those which occurred at other times of the year and which the Heel stone could not predict. Altogether if it was the aim of our priest to impress the peasantry by foreseeing, and thereby seeming to control, these awesome astronomical events his task of appearing 281

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Was Stonehenge a prehistoric computor? if so, which Stonehenge? point of rising or setting. Then the dawn or sunset occurs over the far stone twice—just before and just after the solstice—and while its position is still perceptibly moving; the date of the solstice itself can then be obtained with great accuracy by halving the interval between the two observations. Hoyle then tested Hawkin's alignments to see if they could be explained in this way, by being directed just inside the extreme positions. He found that, this time, the statistics positively favoured this view: there was only a 1 in 1,000 chance that such alignments could have occurred by chance. If the original alignments themselves are accepted as genuine ones between contemporary stones where the angle between extreme summer sunrise/ winter sunset and extreme winter moonset/summer moonrise was 90 degrees. If the Station Stones were set out in Phase II it would suggest that the advantage of the site in this respect was realised secondarily. If the original site was chosen with the Station Stone rectangle in mind then these positions should have been set out in Stage I as Hawkins believes. In this case though it is hard to understand why the Station Stone diagonals miss the centre of Stonehenge I but coincide with that of III.

— an assumption on which everything obviously depends—Hoyle's observations would seem to provide better evidence for Hawkins' views than did the author himself. It certainly makes the technique of observation comprehensible in practical Neolithic terms.

What were the Station Stones used for ?

Concerning the alignments claimed for the sarsen circle and trilithons of Stonehenge III, Atkinson showed that the statistics offered to support them were even more unconvincing. This is perhaps hardly surprising when one considers that accuracy is scarcely possible when the 'foresights' are all wide lintelled archways, and never single stones. Also the bluestone settings put up inside the sarsen circle in Phases IIIb and IIIc would surely have hindered observations from the centre. Altogether Stonehenge III is quite unconvincing as any sort of astronomical instrument.

However the great majority of the alignments for Stonehenge I involve the four Station Stones which stand on the circle of the Aubrey holes (only two of them are still on the site: the sockets of the other two have been located). They formed a rectangle about 105 x 260 ft. which is geometrically linked to the main sarsen circle of Stonehenge IIIa: the diagonals of the rectangle cross at the centre of this circle. Moreover this centre is about 3 ft. S.W. of the common centre of the ditch, bank and Aubrey holes of Stonehenge I. The position of the Station Stones, though perhaps not the stones themselves, could have been established with the bluestone circle in Stage II : this appears to have the same alignment as IIIa. Though this does not prove that the Station Stone rectangle was not of period I it seems unlikely in view of the close link between the diagonals and the circle centre of period III.

However there is more to the Station Stones than surveyors' points to establish the centre of Stonehenge II or III. The short sides of the rectangle point to the extreme northerly and southerly positions of the sun's rising and setting respectively, the long sides to the equivalent lunar positions. The latitude where the angle between these alignments is 90 degrees and will thus permit a rectangle as opposed to a parallelogram to be formed of stones set up to mark them is limited to between about 30 miles north and south of Stone¬ hengle: further north or south the quadrilateral will become progressively more diamond-shaped. This could suggest that Stonehenge was originally sited deliberately at a suitable place in southern England

Could eclipses be predicted ?

The other sophisticated activity which Hawkins suggests was carried on at Stonehenge I was the observation and prediction of eclipses and it involves two suggestions, one plausible and likely and the other possible but unverified. The likely one is that the Heel stone was an indicator of winter eclipses of sun and moon. By using retrospective calculations Hawkins found that, in the second millennium B.C., whenever the full moon nearest to the winter solstice rose over the Heel stone (as seen from the centre of the henge) an eclipse of the sun or moon always followed. Only half these eclipses were visible from southern England, however. Also Hawkins' diagram shows that some eclipses occurred when the moon rose up to 3 degrees to the right or left of the apex of the stone so that the hypothetical Neolithic astronomer would have had a difficult task if this was his only method of foreseeing eclipses. He would have had to guess whether it was the moon or sun which was to be eclipsed and whether the event would be visible from Stonehenge. Also he would inevitably have missed a few which occurred even though the moon rose some way off the Heel stone, as well as those which occurred at other times of the year and which the Heel stone could not predict. Altogether if it was the aim of our priest to impress the peasantry by foreseeing, and thereby seeming to control, these awesome astronomical events his task of appearing

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