The old yard was almost identical to the yard of three feet, but just one hundredth part smaller at 2.87 feet. This gives its foot value as 99/100 feet, a value belonging to a module very close to the English/Greek which defines one relative to the rational ratios of the Historical modules.
So why was this foot and its yard important, in the Scottish megalithic and in later, historical monuments?
If one forms a square with side equal to the old yard, that square can be seen as containing 9 square feet, and each of those has side length 99/100 feet. This can be multiplied by the rough approximation to 1/√ 2 of 5/7 = 0.714285, to obtain a more accurate 1/√ 2 of 99/140 = 0.70714285.
Only two type-D stone circles (see figure 3) are
known to exist, called Roughtor (in Cornwall) and Seascale (in Cumbria). Seascale
is assessed below, for the potential this type of flattened circle had to
provide megalithic astronomers with a calendrical observatory. Seascale could also
have modelled the harmonic ratios of the visible outer planets relative to the
lunar year. Flattened to the north, Seascale now faces Sellafield nuclear
reprocessing plant (figure 1).
Stone Age astronomical monuments went through a
series of evolutionary phases: in Britain c. 3000 BC, stone circles became
widespread until the Late Bronze Age c. 1500 BC. These stone circles manifest
aspects of Late Stone Age art (10,000 – 4500 BC) seen in some of its geometrical
and symbolic forms, in particular as calendrical day tallies scored on bones.
In pre-literate societies, visual art takes on an objective technical function,
especially when focussed upon time and the cyclic phenomena observed within
time. The precedent for Britain’s stone circle culture is that of Brittany,
around Carnac in the south, from where Megalithic Ireland, England and Wales probably
got their own megalithic culture.