  The paper contains a proposed experiment for testing the gravitomagnetic
effect on the propagation of light around a rotating mass. The idea is to use a
rotating spherical laboratory-scale shell, around which two mutually orthogonal
lightguides are wound acting as the arms of an interferometer. Numerical
estimates show that time of flight differences between the equatorial and polar
guides could be in the order of $\sim 10^{-20}$ s, actually detectable with
sensitivity perfectly comparable with those expected in gravitational wave
detection experiments.
