Recall that a geometrical clock is defined as a pair of radar units whose emission of monochromatic wave trains yields two well defined mutual frequency shift factors ( at B and at A) and whose reflective surfaces support an electromagnetic pulse bouncing back and forth between them.

Geometrical clocks differ from one another by virtue of their
differing frequency shift factors and hence their differing ticking
rates. Moreover, these rates are in general not even
uniform. Nevertheless a comparison of these clocks is possible. The
general idea is to consider the *ratio* of their ticking rates.
These ratios open the door to identifying a commensurable property
even among certain geometrical clocks which run nonuniformly relative
to their resident atomic clocks. The implementation of this endeavor
is best done in two steps: first for adjacent clocks, then for distant
ones.

Ulrich Gerlach 2003-02-25