  After studying the design geometry of the Antikythera Mechanism Saros spiral,
new critical geometrical/mechanical characteristics of the Back plate design
were detected. The geometrical characteristics related to the symmetry of the
Antikythera Mechanism design, are independent to the present irregular
deformation of the Mechanism parts and were used as calibration points for the
Saros spiral cells positional measurements. The Saros cells numbering was
recalculated using the calibration points position. A correction of minus one
to the currently accepted numbering of the Saros cells was applied. Following
the new numbering, a new proper position for the (displaced) Saros pointer
axis-g, in graphic design environment was calculated. The measurements were
tested on a bronze reconstruction of the Back plate, by the authors. This
research leads to a new important result that the Saros does not start in a
random or arbitrary date but only when a solar eclipse occurs within a month.
Additional results were also calculated regarding the symmetry of the eclipse
events/sequence. The new Saros cell numbering strongly affects the calculations
for the initial starting date of the Saros spiral and the eclipse events scheme
of the Antikythera Mechanism.
