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