Show Unbreakable Spectacles Unbreakable spectacle lenses are a afi recent Invention in Two pieces of glass fi with mth 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 jast as tran transparent par nt th the ceIl celluloid beIn beIng being be- be In Ing Invisible Unbreakable glass has for Cor some time been employed In the thc windshields of motor vehicles and airplanes air planes and In goggles but this Is believed cd to be Its first use Jn ln spec spec- t |