Missouri’s hot summer days and dark winter afternoons cry out for air circulation and light. Before electricity, transom windows supplied both.

Fortunately for its inhabitants, Tappmeyer Homestead has a transom in almost every room. Downstairs, where the ceilings are 10’ 6”, the transoms are large; upstairs where the ceilings are lower and sometimes sloped, the transoms are smaller, but all serve the same function.

The windows, which are known as early as the fourteenth century, get their name from the transom, a transverse structural beam or bar separating a door from a window above it. The windows are the width of the door and, in older homes, open to provide ventilation. (In modern homes, transoms provide light or architectural accents but aren’t necessary for air flow so don’t open.)

Most transoms open from a hinge on the bottom or top. A chain determines how far the window will open and a long pole mounted on the doorframe releases the latch that keeps the transom closed. Less commonly, transoms open from the side, just as a door does. These allow the user to determine how wide to open the window and provide the greatest amount of airflow. Tappmeyer’s transoms open from the side.

The doors and transoms in the formal parlor and the family living room are designed opposite one another so that when open, the house gets as much air circulation as possible. The family parlor also has a transom over the door to the original kitchen and another from the kitchen to the porch. The hall door to the porch has one too. The transoms over exterior doors allow air in and the interior ones allow it circulate through the house.

Upstairs, the transoms are over the hall doors to the bedrooms to let in as much natural light as possible, which is why they are sometimes called “Borrowed Lights.” They, too, open to circulate air from the windows through the sleeping areas.