The below pictures and instructions
will provide a clue of how these Megaliths were built. This is of
course, the Type B Flat Circle plan. Remember that Professor
Thom found that he could use the Megalithical
Yard to construct these plans. It is suggested that you take
a look at how the Type A Flat Circle is
constructed before going any further.

From the construction of the Type A flat
circle, the properties are as follows.

The horizontal line is the diameter of the red
semi-circle. The two **black** lines (making a V) meets from the
lower quadrant of the red arc, to the midpoints
of the two blue lines respectively.
The two blue lines form a 30 degree angle
with the horizontal line.

Extend lines EC and ED such that the portions of the lines beginning from F and G respectively are equal to FA and GB respectively.

Hence, the lines FA and GB creates the two red
arcs from the fact that they are their radii. Also, The two
lines forming the 'V' are the radii of the green
arc.