NOTE: Sid Lethbridge: Central was acquired by the National Glass Co. in late 1899. In 1901, the Summitville factory was closed and the No. 98 moulds moved to the National factory in Greentown IN where production continued. This was likely the period when cobalt blue was made. At some point moulds were transferred to the Cambridge Glass Co. which started as a National initiative but was independently operated. Cambridge designated this pattern as No. 2510.