I wondered about the Saros at Stonehenge.
My quote 'Figure 5 The Sarsen circle at Stonehenge
Another important cycle of time may also be observed within the boundaries of the Sarsen circle. This is the Saros, a cycle of 6585.321 days. This cycle is used to predict eclipses. The diameter of a circle with an area of 6585.321 square Saxon feet = 91.56 Saxon feet (1208.6 imperial inches). By coincidence, this also falls within the boundaries of the Sarsen circle.'
And it does indeed fall within the boundarie but until Cloister mentioned the number 100.8 imperial feet I simply assumed it was on the outer edge of the sarsen circle.
It works nearly the same way as the metonic cycle at the Rollights.
Saros 94 (diameter of rollrights) x pi = 295.3097094 x 22.3 (there are 223 lunar cycles in the saros and by coincidence 223/71 is Archimedes on measurement of a circle 223/71 or 3.140845) = 6585.40652 the saros.
As with the Rollrights this number is the area of a circle 6585.40652 square saxon feet with diameter = 91.56855355 old Saxon/Indus feet 100.7254 imperial feet (number given by coister).
In addition the Inner Bluestone circle at Stonehenge;
Quote 'The inner bluestone circle Flinders Petrie gives an accurate measure for the inner bluestone circle: ‘The inner bluestones 472.7 ± 0.5 inches diameter’ (p23). This measure also appears to be the inner edge of the circle: 472.7 × π = 1485.03 imperial inches, 123.75 imperial feet and 112.502 Saxon feet for the circumference of this circle. As this is the last circle mentioned in this essay, it may be of interest to study the measure used here and apply it to other circles. The circumference of the inner bluestone circle is 123.75 imperial feet. The old measure can be converted to digits, feet, royal cubits to start: 123.75 imperial feet = 112.5 Saxon feet In turn, this can be converted to digits by multiplying by 16, because there are 16 digits in a foot. Therefore, 112.5 Saxon feet × 16 = 1800 digits. Then it can be converted to royal cubits by dividing the digits by 25, because there are 25 digits in a royal cubit: 1800 ÷ 25 = 72 royal cubits.'
Remember Petrie is measuring to the inner edge of the circle so room to move by 2 inches at least. In any case the circumference of the Sarsen saros circle = 316.4382047 imperial feet which is Bluestone diameter x 8.
316.4382047 / 8 = 39.55477559 imperial feet 474.65 inches (petrie 472.7). The have squared aa circle here as well.