Events on Site - The Stones and the Stars: Building Scotland's Newest Megalith - page 234

industrial and due in large part to steelworks in the Clyde Valley.
Cutbacks the following year brought Tinto Hill into view, alarm-
ingly close to the midwinter sunrise alignment but hidden from us
throughout the project.
The weather had closed in by sunset, and no further observa-
tions were possible that year. With the termination of all STEP
schemes the Astronomy Project was wound up in February 1980,
and practical difficulties prevented any observations in midsum-
mer; in midwinter the weather was again unsuitable. Project
members had participated in the restoration and reopening of Air-
drie Public Observatory, and the contemporary rising of Rigel was
studied during the winter by Paul Benson, one of the curators, but
he concluded that the thickness of the haze and interference of city
lights made Rigel impossible to observe below 20-30° altitude.
Midsummer sunset of 1981 took place on a spectacularly clear
evening and was most informative. Instead of setting on the pitched
roof of the White Horse distillery as predicted (Fig. 8.5a ), the setting
Sun passed behind the peak at the end of the roof only partly hidden
and re-emerged fully to set on the natural skyline beyond (Fig. 8.5b, c ,
d). This was virtually the only event not located on a natural skyline
by calculation, and as it was still over the central stone, and even
over the marker stone (Fig. 8.6a ), with its shadow falling on the cen-
tral stone as intended (Fig. 8.7 ) , it could be said that the discrepancy
improved the functioning of the circle, though the calculated posi-
tion was apparently too far to the left.
The following morning was extremely tantalizing. There was
a low bank of cloud along the northeastern horizon, and the Sun
seemed determined not to leave it. When it did eventually reach
the top of the cloud layer, there was insufficient contrast in the
photographs for its position to be fixed with precision. By then it
was so far from its point of rising that to be accurate both the 'the-
oretical' and 'apparent' tracks in the working photograph would
have had to be shown as curves. All that could be said was that to
be photographed over the central stone in the position shown, the
Sun must have risen fairly close to the predicted point.
Weather again prevented observations in midwinter 1981,
and practical difficulties again intervened in the summer of 1982.
These frustrations were to have a wry counterpart years later,
when Archie Roy was asked to design basic layouts for two circles