Window construction

A hollow double transparent closure comprising:

• a pair of substantially parallel spaced apart panes of transparent sheet material;
• resilient gasket means disposed between the marginal edges of the facing surfaces of said panes, said gasket means having curved compressible faces engaging the adjacent faces of said spaced apart panes and defining an enclosed volume between the facing surfaces of said panes;
• a frame circumscribing the periphery of said panes, said frame including elements of a material of a low thermal conductivity containing grooves for receiving the marginal edges of said panes and having walls of the grooves engaging and urging said panes toward one another to compress said gasket means an amount sufficient to produce an airtight sealing contact between the marginal edges of the facing surfaces of said panes and said gasket means;
• extending tongues on alternate ones of the elements of said frame fitted within the grooves of the adjacent other ones of the elements of said frame;
• flushing gas directing means in the enclosed volume between said facing surfaces of said panes, said directing means being spaced across the planes of the respective panes to sub-divide the enclosed volume between the facing surfaces of said panes;
• and
• fastener means for interconnecting the grooved elements of said frame to form a rigid structure.