The mullion was the vertical bar that divided a window into panes. Wood or stone or iron running up and down the window like the bars of a cage that let the light through. The mullion divided the view into rectangles and each rectangle was its own picture of the street. You looked through a mullioned window and the street came to you in pieces. The mullion was the building's way of saying the world is too big to see all at once.

The mullion held the glass. Before they could make a single sheet of glass big enough for a window they made small sheets and put mullions between them. The mullion was the frame that held the glass the way a sentence holds words. Without the mullion the glass fell out. Without the sentence the words fall out. The mullion was structural and decorative at the same time and it did not know the difference because in 1870 there was no difference.

The mullion made shadows. Sunlight through a mullioned window threw a grid of light and dark on the floor that moved across the room as the day went on. The mullion shadow was the building's sundial. You could tell what time it was by where the shadow fell. Morning the shadow was on the east wall. Afternoon the shadow was on the west wall. The mullion tracked the sun the way the sun tracked the earth. The plate glass window has no shadow. The room is lit the same way all day and you do not know what time it is without a clock.

You painted the mullion. That was the maintenance. You scraped the old paint and puttied the glass and painted the mullion and the paint kept the wood from rotting and the putty kept the rain from getting between the glass and the wood. Painting the mullion was the most tedious job in the apartment and the most satisfying because when you were done the window looked new and the light came through clean. The mullion asked you for a weekend once every five years. That was the deal.

They replaced the mullion with snap-in grilles. Plastic strips that click onto a single pane of glass and pretend to be mullions. The snap-in grille does not hold the glass. The snap-in grille does not make shadows. The snap-in grille is a costume on a window. You pull the grille off and the window is one big sheet of glass and the grille goes in the dishwasher. The real mullion was part of the window. The snap-in grille is a comment about the window. A comment is not the same as a structure.

See also: Shutters, Sash Weight