Time stack photographs were originally used by astronomers to track the positions of stars through the night. Time lapse photographs taken when the camera was on a tripod were superimposed so that the background remaind the same and only the position of the stars changed between each sucessive photograph. The same technique has been used to superimpose light coloured moving objects such as clouds. I have taken time lapse photographs of street scenes and used Photoshop to display the changes between sucessive photographs (which is why the parts that move between one photograph and the next have false colours) and then superimposed them. I have processed the background so that it is sepia coloured and have added noise to make it look like a vintage print. Making it look old echoes the passage of time theme generated by the build up of images taken at 1 second intervals.