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SO 246 608 |
to Bache Hill tumulus 1. |
High precision Megalithic Calendar alignment for sunset at Calendar Intervals 4 & 6 to horizon tumulus and indicated by shadow position arranged on stones.
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| 12th July 1999
Good photographs were secured of sunset on the 12th July 1999. At that moment the Sun's declination was +21 deg. 56.7 min.- some 7 arc minutes short of the ideal required declination +22 deg. 3.6 min. |
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If the position of the setting Sun is corrected to the ideal declination for the Calendar Intervals 4 & 6 we can see how perfectly the upper limb will settle into the fine notch offered by the skirt of the tumulus. |
| At Four Stones great care has been taken in the shaping, or choosing, of the two indicator stones for CI's 4 & 6 so as to allow the shadow of the taller to sit on the smaller at the appropriate sunsets on two days of the year.
This framing, or shuttering, of the shadow could not, of itself, give reliable identification of the days of Calendar Intervals 4 & 6 but it is an indication of the importance of these dates for the maintenance of the Megalithic Calendar. If poor weather obscured sightings of the Sun at the summer solstice, (Calendar interval 5), then the solstice could be calculated in retrospect if two clear observations from these orientated stones were secured, one on either side of the solstice, and the number of days between halved. All of these stones appear to be unworked glacial erratics, possibly carried from moraine fields some 20 miles further west. For this shadow shuttering effect two stones with near identical profiles had to be found, transported and erected at just the right distance that we see here. For more on practical solstitial observation see html page Megalithic Calendar 5 |
This photograph was taken as the lower limb of the Sun sat on the horizon at sunset on the 12th July 1999.
The shadow of the upper half of the larger stone sits cleanly on the smaller stone. |
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1st June 2002.
A second opportunity to record this alignment occurred at sunset on the 1st of June 2002. Here the sun was again close to the ideal declination for the two dates in the Megalithic Calendar, intervals 4 and 6. The disc was resolved sufficiently to make a photographic survey and close estimation of the track of the sun when at the ideal declination for this Calendar Interval. |
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The sun's declination is a little over 3 arc minutes from ideal and a close estimate of the ideal declination for CIs 4 & 6 can be made for this horizon. |
| The shadow indicator.
As noted at the observation of the 12th July 1999 the shadow of the north west stone is clearly framed on the smaller south east stone as the sun sits on the horizon. |
| As the sun approaches the horizon the shadow of one stone moves onto the other. | 
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| When the sun sits 'hull-down', at semi-diameter on the horizon the shadow is perfectly framed by the smaller stone. | 
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| Comparison between the photographic surveys of 1st June 2002 and 12th July 1999. |
| When the two surveys are montaged we can see the close correlation between the two estimates of where the ideal declination track of the upper limb crosses the tumulus. | 
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