Layout and Location - The Stones and the Stars: Building Scotland's Newest Megalith - page 115

As I saw it, there were three different and interacting require-
ments to consider. The first was that there had to be something for
the day to day park visitors to see; the second was that the struc-
ture should be a tribute to or at least a recognition of the ancient
astronomers and their modern interpreters; and thirdly, therefore,
there had to be reasonable astronomical accuracy. Roy pointed out
the problems involved. Within the confines of the circle of any
practical size, it would be impossible to indicate any alignment
with better precision than several solar or lunar diameters. Even
if I used very thin markers, their parallax relative to the horizon
would be significantly affected if the observer shifted his weight
from one foot to the other, or even shut one eye.
Outliers to be seen from the center of the circle, like the Stone-
henge Heelstone, would be an improvement but still only indicate
where to look, as the stone at Kintraw points to the notch in the
profile of Jura. The problem would be to find somewhere in the city
with a clear sight-line to a distant “foresight” and vacant ground
on which to build a megalith. Variations in atmospheric refraction,
within a modern city, would complicate the problem (as indeed
they did - see later). Extended observations would be needed,
furthermore, to make sure of the alignment; and the chances of
having more than one natural foresight would be remote.
Archie's suggestion was that I should compromise on accu-
racy and accept the limitations of working within the city. The
view from his office was marred by a relatively new factory chim-
ney down by the Clyde, in the approximate direction of midwinter
sunset. From a distance of a mile or more, it could provide a rea-
sonably precise marker for the last gleam of sunset, perhaps with
the upper limb just peeping out after passing behind the chim-
ney, before finally vanishing. The exact viewpoint would be criti-
cally dependent on the altitude of the horizon, the height of the
viewpoint above sea level, and using a middle distance viewpoint
there would be lots of refraction to contend with, so the viewpoint
would have to be determined at the solstice by a team of observ-
ers in the traditional manner. The time to midwinter would be
best spent in evaluating promising viewpoints, in relation to open
ground available.
Again, however, there would just be a single alignment and
a structure, circular or otherwise, would be redundant. The work