Abstract: Multiple pane window glass units of the type having abutting pairs of panes fitted between a head and sill. Particularly an "invisible" mullion assembly comprises of a pair of H-shaped vertical channels extending vertically between head and sill and interposed between the vertical edges of each abutting pair of panes so as to stabilize and support the panes of each pair, together with a T-shaped mullion, having an elongate shank with an outer tip vertically extending between abutting pairs of glass pane edges and a flat inner base extending vertically over abutting inner glass pane edges. An outer gasket is fitted over the end of the T-shaped mullion so as to be compressed between the abutting pairs of outer glass pane edges, while engaging said H-shaped channels. A centering guide positions the Y-shaped mullion at the abutting pairs of inner glass pane edges.

Abstract: A multiple pane glass window unit comprising an outboard glass sheet spaced apart from an inboard glass sheet, spacer members positioned between and connected to the horizontal and vertical portions of the glass sheets to space them apart, said spacer members including a horizontal head spacer member connected to a horizontal sill spacer member by a pair of spaced-apart vertical side spacer members, said vertical side spacer members spacing apart the glass sheets and stiffening and supporting the side edge portions of the glass sheets against pressures of wind and rain and the elements, and factory-affixed gasket members attached to the vertical edges of the side spacer members for sealing the vertical space between side-abutting window units, said gasket members being adapted to be compressed between the sides of side-abutting window units, said side spacer members including a side spacer member that is U-shaped in cross-section with the legs of the U facing sideways from the window unit, a foam spacer tape