"Rhytmogramm Nr. 3782/186"

gelatin silver print on Agfa Brovira

The invitation in 1955 to create a mural for the newly constructed School of Engineering in Wolfenbüttel was a welcome occasion for Heidersberger to become more involved with luminography. He began to build a device that he could use to record traces of light directly on photo material. The artist named the pictures he created rhythmograms and continued to pursue his experiments with great enthusiasm. The name he chose was the first indication of the uniqueness of his results.
The rhythmograph, as Heidersberger called his device, was redesigned several times and perfected. The larger version, which was made of a conventional scaffolding, still stands fully functional in the exhibition room of the Heidersberger Institute today and takes up close to twenty square meters of floor space. Using four harmonically muffled pendulums, it creates traces of light on photographic material via a mechanically linked mirror and a point source of light. Three-dimensional images are produced by controlling the frequency, phase difference, amplitude and transmission of the pendulums - two drive the mirror vertically and two horizontally.
(www.heidersberger.de)