One slide projector has been projecting every day full time (24 hours) on the Museum Bochum an outlined drawing, taken from Michelangelo's Sistine ceiling fresco called "The separation of Light and Darkness". This has been done in such way, that the image was never completely visible, because the projection used a wall slice as its screen, which starts outside and continues inside of the building as part of an exhibition space. As the daylight is usually far stronger than any slide projector, visitors may have seen during the day only indoors fragments of the projected image. Every part of the figure, which has been using as a screen an outdoor slice of the wall, remained invisible until dusk. Reciprocal during the evening and the night the projected image has been visible only on the walls outside the building, because the respective wall slice inside have been by then strongly illuminated. Connaturally in the dawn the process becomes inverse again.

Technical data: 1 slide-projector, one slide (blank and black)