Two bowl shaped window panes, thought to be from Turkey, made in style of early crown glass windows, c. 1920. Crown glass was known to the Romans. Although wasteful of glass and only producing small sheets the glass was brilliant and very transparent and thus valued for windows even up to the 19th century.The glass was made from a bubble of glass which was transferred to a pontil iron, cut open and rapidly rotated. Repeated reheating and annealing reulted in a flat disc up to 1.20 m diameter.Crown glass can be identified by its slight convexity and the concentric wavy lines caused by the rotation. Some pieces include the centre boss, or"bull's eye" mark, where the pontil rod was once attached.