  The paper discusses the optimal conguration of one or more ring lasers to be
used for measuring the general relativistic effects of the rotation of the
earth, as manifested on the surface of the planet. The analysis is focused on
devices having their normal vector lying in the meridian plane. The crucial
role of the evaluation of the angles is evidenced. Special attention is paid to
the orientation at the maximum signal, minimizing the sensitivity to the
orientation uncertainty. The use of rings at different latitudes is mentioned
and the problem of the non-sfericity of the earth is commented.
