eight matching c. 1931 cobalt blue glass convex lenses originally used on cove lighting units concealed behind ornamental plaster along the walls of the nortown theater (see additional image). the ground glass lenses were used in the atmospheric style auditorium to emulate a deep blue evening sky. the lenses were manufactured by corning for the major electric equipment co., chicago, il. manufacturer markings are lightly embossed within the center and along the edges of each lens. measures 5 1/2 inches diameter. priced for the lot.