Show unbreakable spectacles spectacle unbreakable spectacle lenses area are a recent invention two pieces of glas with a piece ot of celluloid between them are cemented together under pressure forming one solid piece this glass sandwich Is slightly thicker than ordinary glass but it la is just as transparent the alie celluloid being invisible unbreakable glass has for some time been employed in the windshields wind shields of motor vehicles vehicle and airplanes and in goggles but this Is believed to be its first use in n spectacles |