The figure 0,737 is, therefore, produced from a geometrical relationship between the hexagon and the pentagon. It is the unit of measurement used for the construction of Chartres cathedral.

A further reference to the unit of 0,737, directly related to the position of Chartres, is found on a standard map of France to the scale of 1 :25 000. The position of Chartres is given as 47,27° N, with a degree of parallel of 73.7 Km (Fig 26).

The parallel is the perimeter of the circle which turns about the axis of the earth at the latitude of Chartres. It is found by multiplying 73.7 Km x 360°, or

0,737 mm x 10⁸ x 360°

Finally, the latitude of Chartres at 47,27° N corresponds very closely to the relation between the unit of measurement used for the three tables of the same perimeter (the round table is the labyrinth) and the tables of the same surface area.

0,737 m is the unit of measurement for the tables having the same perimeter, and 0,82 m is the unit of measurement for the tables having the same surface area (see Fig 8 page 13).

Thus, the rectangular table =

32,8 m (or 40 x 0,82) x 16,4 m (or 20 x 0,82)

The square table has a diagonal of 32,8 m (or 40 x 0,82).

The relation between the latitude of Chartres and the two units of measurement is summarised geometrically by constructing a triangle with sides of 0,82 and 0,737, which produces an angle of 48° (Fig 26). The angle being very close to the actual latitude of Chartres at 47,27° N.