Possible evidence from laboratory measurements for a latitude and longitude dependence of G

Stability arguments suggest that the Kaluza-Klein (KK) internal scalar field, $\mathrm{\Phi }$, should be coupled to some external fields. An external bulk real scalar field, $\psi$, minimally coupled to gravity is proved to be satisfactory. At low temperature, the coupling of $\psi$ to the electromagnetic (EM) field allows $\mathrm{\Phi }$ to be much stronger coupled to the EM field than in the genuine five dimensional KK theory. It is shown that the coupling of $\mathrm{\Phi }$ to the geomagnetic field may explain the observed dispersion in laboratory measurements of the (effective) gravitational constant. The analysis takes into account the spatial variations of the geomagnetic field. Except the high PTB value, the predictions are found in good agreement with all of the experimental data.