Tribune caption on the back, March 7, 1973- "Bill Walker photographs a jet departing Oakland Airport. Grid on window shows the plane's altitude and the time of day." Handwritten above this "Test House with grid and plane. Bill Walker- photog." Photo shows the back of a man with a camera on a tripod standing in front of a window. Through the window can be seen a tall grid with the date is free-standing letters attached to the side of the grid and a clock in the middle of the grid. A plane is in the distance.