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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