Possible Clues:

• They start in the middle
• Bones found in river two years after the Massacre of the Innocents?
• 6's 2 across
• - - vectores, straight lines connecting fixed and variable points
• Pizza slice borders, e.g.
• Revolutionary type with two spokes
• More than one spoke, with transmitter cutting off last one
• Geometry calculations
• Diameter sections
• Half-Welsh 1 across with two circular lines