Et per ea signa et centrum a lineae ad extremas lineae circinationis sunt perducendae, ubi erunt litterae q et p; haec erit linea pros orthas radio aequinoctiali.
Through those letters and the centre a, a line is to be produced to the circumference at the points q and p. This line will be perpendicular to the equinoctial ray;
final_alignments\Vitruvius_Architecture_Book_9.json