A number of continuous-sheet memory cells have been studied magneto-optically by means of the Faraday rotation in the Ce(PO3)3 glass. The data have been correlated with the results of simultaneous electrical measurements. Near the storage threshold, the observed storage of these cells is similar to that of an isothermal Crowe cell. When the cells are operated with larger drive currents, deviations from the simple isothermal Crowe-cell model are noted. These deviations are interpreted in terms of the spreading of the trapped flux in the continuous-sheet cell and in terms of heating. © 1963.