Abstract: In an apparatus for forming multiple ply sheet glass directly from separate sources of molten vitreous material while maintaining such separate sources free from exposure to detrimental gaseous media during the formation of such sheet glass; metering means in communication with each of said separate sources of vitreous material, a pair of opposed surface portions thereof defining a central longitudinal delivery passage for delivering molten glass from one source of vitreous material, and a pair of opposed channels for delivering molten glass from the other source, insert means adapted to mate with the metering means in said delivery passage for reducing the flow of molten glass therethrough to provide sheet glass having a width narrower than the width of said delivery passage.