BENDING THICK GLASS INTO HERMISPHERICAL SHAPES COMPRISING USING A MOLD OF CONCAVE ELEVATION OF MATERIAL HAVING LESS THERMAL EXPANSIVITY THAN GLASS, SAID MOLD COMPRISING A RING OF RIGID MATERIAL HAVING GREATER THERMAL EXPANSIVITY THAN GLASS AND SUFFICIENTLY SMALLER IN DIAMETER THAN THE MOLD AT GLASS LOADING TEMPERATURE TO SUPORT THE GLASS

OVER SAID MOLD AT THE TEMPERATURE AT WHICH THE MOLD IS LOADED AND CAPABLE OF EXPANDING SUFFICIENTLY MORE RAPIDLY THAN THE MOLD TO DEPOSIT THE GLASS ONTO THE MOLD AFTER THE GLASS HAS ATTAINED A SUFFICIENTLY HIGH TEMPERATURE TO DEFORM IN RESPONSE TO EXTERNAL STRESSES.