In 1964, Dr. Robert Steele, film professor at Boston University, performed the very first scientific study of light rhythm in the cinema. His novel approach was to make line graphs of the amount of light and changes in the amount of light during the showing of a film. His apparatus consisted of a 16mm projector that projected light through a paper tube and onto a photo-electric cell. There the intensity of the light was translated into an electrical signal which, in turn, made a needle on an event-recorder draw a line onto a paper chart.
In this dramatization, the paper tube glows brilliantly during a bright scene in the film.
Barely visible at the bottom is a strip of paper containing the chart of the film.
Looking like seismographs, Dr. Steele's charts record the changes in the amount of light during the showing of a film. His hypothesis was that measurable evidence of light rhythm could reveal the secrets of great filmmaking. Studying only a small sampling of film, Dr. Steele struggled to correlate areas of measurable light rhythm with the intentions of the filmmaker.
There were many contributing factors which prevented Dr. Steele from producing clear evidence of light rhythm in the cinema. First was the technological restrictions. His novel apparatus was only able to chart the light rhythm of one film at a time in real time. Secondly, the film that he sampled were not films in which direct attention was paid to the effect of light rhythm. In the image below we see Dr. Steele's hand written notes as he searched for light rhythm in the famous Odessa Steps sequence of Eisenstein's 1925 classic, Battleship Potemkin.