Free Before the Pyramids: Cracking Archaeology's Greatest Mystery by Christopher Knight, Alan Butler Page B

the sky from the perspective of the observer. In addition, as a person moves east or west, the time of day of any stars rising changes. With accurate time-keeping (using a pendulum) it is possible to measure distance on the Earth’s surface ( see figure 7). For a full explanation of how pendulums were used to measure a multitude of different astronomical happenings see Appendix 4.
    If a Neolithic sky-watcher understood the culmination rule, he could erect a pole at two different places and gauge the difference in terms of Megalithic Degrees or seconds of arc. An archaeologist would quickly point out that because they ‘could’ have done something does not prove that they ‘did’, unless there are datable artefacts to support a claim. As these people did not have metals we are unlikely to find any tool that represents a modern sextant, but there are many ways to measure relative angles.

    Figure 7. A simple pendulum
    But, even without unearthing a prehistoric sextant we can be sure that these henge builders could measure latitude from the stars.
    When we checked the difference in latitude between the centres of the outer henges we found there is exactly 4 Msec of arc (41 × 366 MY) between them.
    This was astonishing! The accuracy of measurement is simply incredible, given that the Megalithic Second of arc is the smallest unit of geometric division apart from the Megalithic Yard itself, but the facts speak for themselves. Highly competent astronomers built these Neolithic structures. We were at a loss to understand how they could have measured such fine differences in latitude – but it seemed that somehow they did.
    Next we pulled back to take in the bigger picture. Given the science that we could now see underpins the entire site of these gigantic structures we needed to consider why the people creating them had constructed a slightly bent alignment and built them with openings to each henge along an avenue pointing approximately northwest to southeast.
    The first thing that is obvious is that the site is remarkably flat with only a very gentle slope from north to south. There are no large hills in the vicinity and so the view to all sides of the henges is unobstructed. There are hills in the distance, especially to the east, but when the banks were fully in place these would have been obscured. All heavenly bodies seen from the centre of any of the henges would rise from and fall back to the top of the banks, and there are no reference points on the horizon as are found at many stone circles. This is because from inside the henges there are no natural horizons to be seen, except through the deliberately engineered openings.
    The location of the Thornborough henges is unusual in a British upland context because there are no hills of note for a staggering 127. 9 km (79.5 miles) to the southeast; the first being the 77 m-high hill upon which Lincoln Cathedral now stands. Strangely, the angle of the central and southern henges, their openings and the avenue, all point like a gun sight in the direction of the Lincoln mound. We could not think of any other location in the British Isles that delivers up such a long stretch of almost flat land. This seemed unlikely to be coincidence.
    But what function could this virtual sightline serve? The curvature of the Earth makes it impossible to see such a distance but is there something significant about the location of Lincoln Cathedral? We were well aware that churches were often built on the ancient ‘holy’ sites from prehistory. Indeed, the tallest megalithic standing stone in Britain, with a height of 8 m and a circumference of 5 m, stands next to an old church in the village of Rudston, close to where Alan lives. The church and its graveyard were built inside Neolithic earthworks.
    The distance between the centre of the southern Thornborough henge and the highest point at Lincoln is 127.13 km, which does not convert to any apparently meaningful distance in megalithic units.