George L. Stout, head of the Department of Technical Research at the Fogg Art Museum, and John S. Thatcher, Assistant Director of the same museum announced yesterday that the cross on Bishop Lawrence's chest in his portrait in Leverett dining hall is caused by variations in the moisture content of the paint and the support.

After carefully examining the cross, Stout stated in his official "Observations on the Condition of a Portrait of Bishop William Lawrence by Charles Hopkinson": "In reflected light, there appears in the painting an inconsistency of surface character along narrow bands which extend vertically and horizontally through the center of the canvas and around the four sides.

"The bands are about three inches wide, and from them light is reflected more uniformly than from the rest of the surface.

"Alternate condensation on the wall and drying from the radiator below would cause a wide variation in the moisture content of the paint and support. Those parts of the canvas and the paint film next the stretcher piece would have a steady moistness."