  Conductivity and field effect measurements in thin insulating Al granular
films are reported. The occurrence of a symmetrical field effect and of very
slow conductance relaxations is demonstrated. They are identical to the
electron glassy behaviours already reported in insulating indium oxide thin
films. The results suggest that the phenomena are quite general. The study of
structurally discontinuous samples should help to understand the origin and
mechanism of the glassy behaviour.
